-/* $Cambridge: exim/src/src/tls-gnu.c,v 1.19 2007/04/13 15:13:47 ph10 Exp $ */
-
/*************************************************
* Exim - an Internet mail transport agent *
*************************************************/
-/* Copyright (c) University of Cambridge 1995 - 2007 */
+/* Copyright (c) The Exim Maintainers 2020 - 2022 */
+/* Copyright (c) University of Cambridge 1995 - 2018 */
+/* Copyright (c) Phil Pennock 2012 */
/* See the file NOTICE for conditions of use and distribution. */
+/* SPDX-License-Identifier: GPL-2.0-only */
+
+/* This file provides TLS/SSL support for Exim using the GnuTLS library,
+one of the available supported implementations. This file is #included into
+tls.c when USE_GNUTLS has been set.
-/* This module provides TLS (aka SSL) support for Exim using the GnuTLS
-library. It is #included into tls.c when that library is used. The code herein
-is based on a patch that was contributed by Nikos Mavroyanopoulos.
+The code herein is a revamp of GnuTLS integration using the current APIs; the
+original tls-gnu.c was based on a patch which was contributed by Nikos
+Mavrogiannopoulos. The revamp is partially a rewrite, partially cut&paste as
+appropriate.
-No cryptographic code is included in Exim. All this module does is to call
-functions from the GnuTLS library. */
+APIs current as of GnuTLS 2.12.18; note that the GnuTLS manual is for GnuTLS 3,
+which is not widely deployed by OS vendors. Will note issues below, which may
+assist in updating the code in the future. Another sources of hints is
+mod_gnutls for Apache (SNI callback registration and handling).
+Keeping client and server variables more split than before and is currently
+the norm, in anticipation of TLS in ACL callouts.
-/* Heading stuff for GnuTLS */
+I wanted to switch to gnutls_certificate_set_verify_function() so that
+certificate rejection could happen during handshake where it belongs, rather
+than being dropped afterwards, but that was introduced in 2.10.0 and Debian
+(6.0.5) is still on 2.8.6. So for now we have to stick with sub-par behaviour.
+
+(I wasn't looking for libraries quite that old, when updating to get rid of
+compiler warnings of deprecated APIs. If it turns out that a lot of the rest
+require current GnuTLS, then we'll drop support for the ancient libraries).
+*/
#include <gnutls/gnutls.h>
+/* needed for cert checks in verification and DN extraction: */
#include <gnutls/x509.h>
+/* man-page is incorrect, gnutls_rnd() is not in gnutls.h: */
+#include <gnutls/crypto.h>
+
+/* needed to disable PKCS11 autoload unless requested */
+#if GNUTLS_VERSION_NUMBER >= 0x020c00
+# include <gnutls/pkcs11.h>
+# define SUPPORT_PARAM_TO_PK_BITS
+#endif
+#if GNUTLS_VERSION_NUMBER < 0x030103 && !defined(DISABLE_OCSP)
+# warning "GnuTLS library version too old; define DISABLE_OCSP in Makefile"
+# define DISABLE_OCSP
+#endif
+#if GNUTLS_VERSION_NUMBER < 0x020a00 && !defined(DISABLE_EVENT)
+# warning "GnuTLS library version too old; tls:cert event unsupported"
+# define DISABLE_EVENT
+#endif
+#if GNUTLS_VERSION_NUMBER >= 0x030000
+# define SUPPORT_SELFSIGN /* Uncertain what version is first usable but 2.12.23 is not */
+#endif
+#if GNUTLS_VERSION_NUMBER >= 0x030306
+# define SUPPORT_CA_DIR
+#else
+# undef SUPPORT_CA_DIR
+#endif
+#if GNUTLS_VERSION_NUMBER >= 0x030014
+# define SUPPORT_SYSDEFAULT_CABUNDLE
+#endif
+#if GNUTLS_VERSION_NUMBER >= 0x030104
+# define GNUTLS_CERT_VFY_STATUS_PRINT
+#endif
+#if GNUTLS_VERSION_NUMBER >= 0x030109
+# define SUPPORT_CORK
+#endif
+#if GNUTLS_VERSION_NUMBER >= 0x03010a
+# define SUPPORT_GNUTLS_SESS_DESC
+#endif
+#if GNUTLS_VERSION_NUMBER >= 0x030300
+# define GNUTLS_AUTO_GLOBAL_INIT
+# define GNUTLS_AUTO_PKCS11_MANUAL
+#endif
+#if (GNUTLS_VERSION_NUMBER >= 0x030404) \
+ || (GNUTLS_VERSION_NUMBER >= 0x030311) && (GNUTLS_VERSION_NUMBER & 0xffff00 == 0x030300)
+# ifndef DISABLE_OCSP
+# define EXIM_HAVE_OCSP
+# endif
+#endif
+#if GNUTLS_VERSION_NUMBER >= 0x030500
+# define SUPPORT_GNUTLS_KEYLOG
+#endif
+#if GNUTLS_VERSION_NUMBER >= 0x030506 && !defined(DISABLE_OCSP)
+# define SUPPORT_SRV_OCSP_STACK
+#endif
+#if GNUTLS_VERSION_NUMBER >= 0x030603
+# define EXIM_HAVE_TLS1_3
+# define SUPPORT_GNUTLS_EXT_RAW_PARSE
+# define GNUTLS_OCSP_STATUS_REQUEST_GET2
+#endif
+
+#ifdef SUPPORT_DANE
+# if GNUTLS_VERSION_NUMBER >= 0x030000
+# define DANESSL_USAGE_DANE_TA 2
+# define DANESSL_USAGE_DANE_EE 3
+# else
+# error GnuTLS version too early for DANE
+# endif
+# if GNUTLS_VERSION_NUMBER < 0x999999
+# define GNUTLS_BROKEN_DANE_VALIDATION
+# endif
+#endif
+
+#ifndef DISABLE_TLS_RESUME
+# if GNUTLS_VERSION_NUMBER >= 0x030603
+# define EXIM_HAVE_TLS_RESUME
+# else
+# warning "GnuTLS library version too old; resumption unsupported"
+# endif
+#endif
+
+#if GNUTLS_VERSION_NUMBER >= 0x030200
+# ifdef SUPPORT_GNUTLS_EXT_RAW_PARSE
+# define EXIM_HAVE_ALPN
+# endif
+#endif
+
+#if GNUTLS_VERSION_NUMBER >= 0x030702
+# define HAVE_GNUTLS_EXPORTER
+#endif
+
+#ifndef DISABLE_OCSP
+# include <gnutls/ocsp.h>
+#endif
+#ifdef SUPPORT_DANE
+# include <gnutls/dane.h>
+#endif
+
+#include "tls-cipher-stdname.c"
+
+
+#ifdef MACRO_PREDEF
+void
+options_tls(void)
+{
+# ifndef DISABLE_TLS_RESUME
+builtin_macro_create_var(US"_RESUME_DECODE", RESUME_DECODE_STRING );
+# endif
+# ifdef EXIM_HAVE_TLS1_3
+builtin_macro_create(US"_HAVE_TLS1_3");
+# endif
+# ifdef EXIM_HAVE_OCSP
+builtin_macro_create(US"_HAVE_TLS_OCSP");
+# endif
+# ifdef SUPPORT_SRV_OCSP_STACK
+builtin_macro_create(US"_HAVE_TLS_OCSP_LIST");
+# endif
+#if defined(EXIM_HAVE_INOTIFY) || defined(EXIM_HAVE_KEVENT)
+builtin_macro_create(US"_HAVE_TLS_CA_CACHE");
+# endif
+# ifdef EXIM_HAVE_ALPN
+builtin_macro_create(US"_HAVE_TLS_ALPN");
+# endif
+}
+#else
-#define UNKNOWN_NAME "unknown"
-#define DH_BITS 1024
-#define PARAM_SIZE 2*1024
+/* GnuTLS 2 vs 3
+GnuTLS 3 only:
+ gnutls_global_set_audit_log_function()
-/* Values for verify_requirment and initialized */
+Changes:
+ gnutls_certificate_verify_peers2(): is new, drop the 2 for old version
+*/
-enum { VERIFY_NONE, VERIFY_OPTIONAL, VERIFY_REQUIRED };
-enum { INITIALIZED_NOT, INITIALIZED_SERVER, INITIALIZED_CLIENT };
+/* Local static variables for GnuTLS */
-/* Local static variables for GNUTLS */
+/* Values for verify_requirement */
-static BOOL initialized = INITIALIZED_NOT;
-static host_item *client_host;
+enum peer_verify_requirement
+ { VERIFY_NONE, VERIFY_OPTIONAL, VERIFY_REQUIRED, VERIFY_DANE };
-static gnutls_dh_params dh_params = NULL;
+/* This holds most state for server or client; with this, we can set up an
+outbound TLS-enabled connection in an ACL callout, while not stomping all
+over the TLS variables available for expansion.
-static gnutls_certificate_server_credentials x509_cred = NULL;
-static gnutls_session tls_session = NULL;
+Some of these correspond to variables in globals.c; those variables will
+be set to point to content in one of these instances, as appropriate for
+the stage of the process lifetime.
-static char ssl_errstring[256];
+Not handled here: global tlsp->tls_channelbinding.
+*/
-static int ssl_session_timeout = 200;
-static int verify_requirement;
+typedef struct exim_gnutls_state {
+ gnutls_session_t session;
+
+ exim_tlslib_state lib_state;
+#define x509_cred libdata0
+#define pri_cache libdata1
+
+ enum peer_verify_requirement verify_requirement;
+ int fd_in;
+ int fd_out;
+
+ BOOL peer_cert_verified:1;
+ BOOL peer_dane_verified:1;
+ BOOL trigger_sni_changes:1;
+ BOOL have_set_peerdn:1;
+ BOOL xfer_eof:1; /*XXX never gets set! */
+ BOOL xfer_error:1;
+#ifdef SUPPORT_CORK
+ BOOL corked:1;
+#endif
+
+ const struct host_item *host; /* NULL if server */
+ gnutls_x509_crt_t peercert;
+ uschar *peerdn;
+ uschar *ciphersuite;
+ uschar *received_sni;
+
+ const uschar *tls_certificate;
+ const uschar *tls_privatekey;
+ const uschar *tls_sni; /* client send only, not received */
+ const uschar *tls_verify_certificates;
+ const uschar *tls_crl;
+ const uschar *tls_require_ciphers;
+
+ uschar *exp_tls_certificate;
+ uschar *exp_tls_privatekey;
+ uschar *exp_tls_verify_certificates;
+ uschar *exp_tls_crl;
+ uschar *exp_tls_require_ciphers;
+ const uschar *exp_tls_verify_cert_hostnames;
+#ifndef DISABLE_EVENT
+ uschar *event_action;
+#endif
+#ifdef SUPPORT_DANE
+ char * const * dane_data;
+ const int * dane_data_len;
+#endif
+
+ tls_support *tlsp; /* set in tls_init() */
+
+ uschar *xfer_buffer;
+ int xfer_buffer_lwm;
+ int xfer_buffer_hwm;
+} exim_gnutls_state_st;
+
+static const exim_gnutls_state_st exim_gnutls_state_init = {
+ /* all elements not explicitly intialised here get 0/NULL/FALSE */
+ .fd_in = -1,
+ .fd_out = -1,
+};
-/* Priorities for TLS algorithms to use. In each case there's a default table,
-and space into which it can be copied and altered. */
+/* Not only do we have our own APIs which don't pass around state, assuming
+it's held in globals, GnuTLS doesn't appear to let us register callback data
+for callbacks, or as part of the session, so we have to keep a "this is the
+context we're currently dealing with" pointer and rely upon being
+single-threaded to keep from processing data on an inbound TLS connection while
+talking to another TLS connection for an outbound check. This does mean that
+there's no way for heart-beats to be responded to, for the duration of the
+second connection.
+XXX But see gnutls_session_get_ptr()
+*/
-static const int default_proto_priority[16] = {
- GNUTLS_TLS1,
- GNUTLS_SSL3,
- 0 };
+static exim_gnutls_state_st state_server = {
+ /* all elements not explicitly intialised here get 0/NULL/FALSE */
+ .fd_in = -1,
+ .fd_out = -1,
+};
-static int proto_priority[16];
+/* dh_params are initialised once within the lifetime of a process using TLS;
+if we used TLS in a long-lived daemon, we'd have to reconsider this. But we
+don't want to repeat this. */
-static const int default_kx_priority[16] = {
- GNUTLS_KX_RSA,
- GNUTLS_KX_DHE_DSS,
- GNUTLS_KX_DHE_RSA,
- 0 };
+static gnutls_dh_params_t dh_server_params = NULL;
-static int kx_priority[16];
+static int ssl_session_timeout = 7200; /* Two hours */
-static int default_cipher_priority[16] = {
- GNUTLS_CIPHER_AES_256_CBC,
- GNUTLS_CIPHER_AES_128_CBC,
- GNUTLS_CIPHER_3DES_CBC,
- GNUTLS_CIPHER_ARCFOUR_128,
- 0 };
+static const uschar * const exim_default_gnutls_priority = US"NORMAL";
-static int cipher_priority[16];
+/* Guard library core initialisation */
-static const int default_mac_priority[16] = {
- GNUTLS_MAC_SHA,
- GNUTLS_MAC_MD5,
- 0 };
+static BOOL exim_gnutls_base_init_done = FALSE;
-static int mac_priority[16];
+#ifndef DISABLE_OCSP
+static BOOL gnutls_buggy_ocsp = FALSE;
+static BOOL exim_testharness_disable_ocsp_validity_check = FALSE;
+#endif
-/* These two are currently not changeable. */
+#ifdef EXIM_HAVE_ALPN
+static int server_seen_alpn = -1; /* count of names */
+#endif
+#ifdef EXIM_HAVE_TLS_RESUME
+static gnutls_datum_t server_sessticket_key;
+#endif
-static const int comp_priority[16] = { GNUTLS_COMP_NULL, 0 };
-static const int cert_type_priority[16] = { GNUTLS_CRT_X509, 0 };
-/* Tables of priority names and equivalent numbers */
+/* ------------------------------------------------------------------------ */
+/* macros */
-typedef struct pri_item {
- uschar *name;
- int *values;
-} pri_item;
+#define MAX_HOST_LEN 255
+/* Set this to control gnutls_global_set_log_level(); values 0 to 9 will setup
+the library logging; a value less than 0 disables the calls to set up logging
+callbacks. GNuTLS also looks for an environment variable - except not for
+setuid binaries, making it useless - "GNUTLS_DEBUG_LEVEL".
+Allegedly the testscript line "GNUTLS_DEBUG_LEVEL=9 sudo exim ..." would work,
+but the env var must be added to /etc/sudoers too. */
+#ifndef EXIM_GNUTLS_LIBRARY_LOG_LEVEL
+# define EXIM_GNUTLS_LIBRARY_LOG_LEVEL -1
+#endif
-static int tls1_codes[] = { GNUTLS_TLS1, 0 };
-static int ssl3_codes[] = { GNUTLS_SSL3, 0 };
+#ifndef EXIM_CLIENT_DH_MIN_BITS
+# define EXIM_CLIENT_DH_MIN_BITS 1024
+#endif
-static pri_item proto_index[] = {
- { US"TLS1", tls1_codes },
- { US"SSL3", ssl3_codes }
-};
+/* With GnuTLS 2.12.x+ we have gnutls_sec_param_to_pk_bits() with which we
+can ask for a bit-strength. Without that, we stick to the constant we had
+before, for now. */
+#ifndef EXIM_SERVER_DH_BITS_PRE2_12
+# define EXIM_SERVER_DH_BITS_PRE2_12 1024
+#endif
+#define Expand_check_tlsvar(Varname, errstr) \
+ expand_check(state->Varname, US #Varname, &state->exp_##Varname, errstr)
-static int kx_rsa_codes[] = { GNUTLS_KX_RSA,
- GNUTLS_KX_DHE_RSA, 0 };
-static int kx_dhe_codes[] = { GNUTLS_KX_DHE_DSS,
- GNUTLS_KX_DHE_RSA, 0 };
-static int kx_dhe_dss_codes[] = { GNUTLS_KX_DHE_DSS, 0 };
-static int kx_dhe_rsa_codes[] = { GNUTLS_KX_DHE_RSA, 0 };
+#if GNUTLS_VERSION_NUMBER >= 0x020c00
+# define HAVE_GNUTLS_SESSION_CHANNEL_BINDING
+# define HAVE_GNUTLS_SEC_PARAM_CONSTANTS
+# define HAVE_GNUTLS_RND
+/* The security fix we provide with the gnutls_allow_auto_pkcs11 option
+ * (4.82 PP/09) introduces a compatibility regression. The symbol simply
+ * isn't available sometimes, so this needs to become a conditional
+ * compilation; the sanest way to deal with this being a problem on
+ * older OSes is to block it in the Local/Makefile with this compiler
+ * definition */
+# ifndef AVOID_GNUTLS_PKCS11
+# define HAVE_GNUTLS_PKCS11
+# endif /* AVOID_GNUTLS_PKCS11 */
+#endif
-static pri_item kx_index[] = {
- { US"DHE_DSS", kx_dhe_dss_codes },
- { US"DHE_RSA", kx_dhe_rsa_codes },
- { US"RSA", kx_rsa_codes },
- { US"DHE", kx_dhe_codes }
-};
+#if GNUTLS_VERSION_NUMBER >= 0x030404
+# define HAVE_GNUTLS_PRF_RFC5705
+#endif
-static int arcfour_128_codes[] = { GNUTLS_CIPHER_ARCFOUR_128, 0 };
-static int arcfour_40_codes[] = { GNUTLS_CIPHER_ARCFOUR_40, 0 };
-static int arcfour_codes[] = { GNUTLS_CIPHER_ARCFOUR_128,
- GNUTLS_CIPHER_ARCFOUR_40, 0 };
-static int aes_256_codes[] = { GNUTLS_CIPHER_AES_256_CBC, 0 };
-static int aes_128_codes[] = { GNUTLS_CIPHER_AES_128_CBC, 0 };
-static int aes_codes[] = { GNUTLS_CIPHER_AES_256_CBC,
- GNUTLS_CIPHER_AES_128_CBC, 0 };
-static int des3_codes[] = { GNUTLS_CIPHER_3DES_CBC, 0 };
-
-static pri_item cipher_index[] = {
- { US"ARCFOUR_128", arcfour_128_codes },
- { US"ARCFOUR_40", arcfour_40_codes },
- { US"ARCFOUR", arcfour_codes },
- { US"AES_256", aes_256_codes },
- { US"AES_128", aes_128_codes },
- { US"AES", aes_codes },
- { US"3DES", des3_codes }
-};
+/* ------------------------------------------------------------------------ */
+/* Callback declarations */
-static int mac_sha_codes[] = { GNUTLS_MAC_SHA, 0 };
-static int mac_md5_codes[] = { GNUTLS_MAC_MD5, 0 };
+#if EXIM_GNUTLS_LIBRARY_LOG_LEVEL >= 0
+static void exim_gnutls_logger_cb(int level, const char *message);
+#endif
-static pri_item mac_index[] = {
- { US"SHA", mac_sha_codes },
- { US"SHA1", mac_sha_codes },
- { US"MD5", mac_md5_codes }
-};
+static int exim_sni_handling_cb(gnutls_session_t session);
+#ifdef EXIM_HAVE_TLS_RESUME
+static int
+tls_server_ticket_cb(gnutls_session_t sess, u_int htype, unsigned when,
+ unsigned incoming, const gnutls_datum_t * msg);
+#endif
/*************************************************
Argument:
prefix text to include in the logged error
+ msg additional error string (may be NULL)
+ usually obtained from gnutls_strerror()
host NULL if setting up a server;
the connected host if setting up a client
- err a GnuTLS error number, or 0 if local error
+ errstr pointer to returned error string
Returns: OK/DEFER/FAIL
*/
static int
-tls_error(uschar *prefix, host_item *host, int err)
+tls_error(const uschar *prefix, const uschar *msg, const host_item *host,
+ uschar ** errstr)
{
-uschar *errtext = US"";
-if (err != 0) errtext = string_sprintf(": %s", gnutls_strerror(err));
-if (host == NULL)
- {
- log_write(0, LOG_MAIN, "TLS error on connection from %s (%s)%s",
- (sender_fullhost != NULL)? sender_fullhost : US "local process",
- prefix, errtext);
- return DEFER;
- }
-else
+if (errstr)
+ *errstr = string_sprintf("(%s)%s%s", prefix, msg ? ": " : "", msg ? msg : US"");
+return host ? FAIL : DEFER;
+}
+
+
+static int
+tls_error_gnu(exim_gnutls_state_st * state, const uschar *prefix, int err,
+ uschar ** errstr)
+{
+return tls_error(prefix,
+ state && err == GNUTLS_E_FATAL_ALERT_RECEIVED
+ ? US gnutls_alert_get_name(gnutls_alert_get(state->session))
+ : US gnutls_strerror(err),
+ state ? state->host : NULL,
+ errstr);
+}
+
+static int
+tls_error_sys(const uschar *prefix, int err, const host_item *host,
+ uschar ** errstr)
+{
+return tls_error(prefix, US strerror(err), host, errstr);
+}
+
+
+/* ------------------------------------------------------------------------ */
+/* Initialisation */
+
+#ifndef DISABLE_OCSP
+
+static BOOL
+tls_is_buggy_ocsp(void)
+{
+const uschar * s;
+uschar maj, mid, mic;
+
+s = CUS gnutls_check_version(NULL);
+maj = atoi(CCS s);
+if (maj == 3)
{
- log_write(0, LOG_MAIN, "TLS error on connection to %s [%s] (%s)%s",
- host->name, host->address, prefix, errtext);
- return FAIL;
+ while (*s && *s != '.') s++;
+ mid = atoi(CCS ++s);
+ if (mid <= 2)
+ return TRUE;
+ else if (mid >= 5)
+ return FALSE;
+ else
+ {
+ while (*s && *s != '.') s++;
+ mic = atoi(CCS ++s);
+ return mic <= (mid == 3 ? 16 : 3);
+ }
}
+return FALSE;
}
+#endif
-/*************************************************
-* Verify certificate *
-*************************************************/
+static int
+tls_g_init(uschar ** errstr)
+{
+int rc;
+DEBUG(D_tls) debug_printf("GnuTLS global init required\n");
+
+#if defined(HAVE_GNUTLS_PKCS11) && !defined(GNUTLS_AUTO_PKCS11_MANUAL)
+/* By default, gnutls_global_init will init PKCS11 support in auto mode,
+which loads modules from a config file, which sounds good and may be wanted
+by some sysadmin, but also means in common configurations that GNOME keyring
+environment variables are used and so breaks for users calling mailq.
+To prevent this, we init PKCS11 first, which is the documented approach. */
+
+if (!gnutls_allow_auto_pkcs11)
+ if ((rc = gnutls_pkcs11_init(GNUTLS_PKCS11_FLAG_MANUAL, NULL)))
+ return tls_error_gnu(NULL, US"gnutls_pkcs11_init", rc, errstr);
+#endif
+
+#ifndef GNUTLS_AUTO_GLOBAL_INIT
+if ((rc = gnutls_global_init()))
+ return tls_error_gnu(NULL, US"gnutls_global_init", rc, errstr);
+#endif
+
+#if EXIM_GNUTLS_LIBRARY_LOG_LEVEL >= 0
+DEBUG(D_tls)
+ {
+ gnutls_global_set_log_function(exim_gnutls_logger_cb);
+ /* arbitrarily chosen level; bump up to 9 for more */
+ gnutls_global_set_log_level(EXIM_GNUTLS_LIBRARY_LOG_LEVEL);
+ }
+#endif
-/* Called after a successful handshake, when certificate verification is
-required or optional, for both server and client.
+#ifndef DISABLE_OCSP
+if (tls_ocsp_file && (gnutls_buggy_ocsp = tls_is_buggy_ocsp()))
+ log_write(0, LOG_MAIN, "OCSP unusable with this GnuTLS library version");
+#endif
-Arguments:
- session GNUTLS session
- error where to put text giving a reason for failure
+exim_gnutls_base_init_done = TRUE;
+return OK;
+}
-Returns: TRUE/FALSE
-*/
-static BOOL
-verify_certificate(gnutls_session session, uschar **error)
+
+/* Daemon-call before each connection. Nothing to do for GnuTLS. */
+
+static void
+tls_per_lib_daemon_tick(void)
{
-int verify;
-uschar *dn_string = US"";
-const gnutls_datum *cert;
-unsigned int cert_size = 0;
+}
+
+/* Daemon one-time initialisation */
-*error = NULL;
+static void
+tls_per_lib_daemon_init(void)
+{
+uschar * dummy_errstr;
+static BOOL once = FALSE;
-/* Get the peer's certificate. If it sent one, extract it's DN, and then
-attempt to verify the certificate. If no certificate is supplied, verification
-is forced to fail. */
+if (!exim_gnutls_base_init_done)
+ tls_g_init(&dummy_errstr);
-cert = gnutls_certificate_get_peers(session, &cert_size);
-if (cert != NULL)
+if (!once)
{
- uschar buff[1024];
- gnutls_x509_crt gcert;
+ once = TRUE;
- gnutls_x509_crt_init(&gcert);
- dn_string = US"unknown";
+#ifdef EXIM_HAVE_TLS_RESUME
+ /* We are dependent on the GnuTLS implementation of the Session Ticket
+ encryption; both the strength and the key rotation period. We hope that
+ the strength at least matches that of the ciphersuite (but GnuTLS does not
+ document this). */
- if (gnutls_x509_crt_import(gcert, cert, GNUTLS_X509_FMT_DER) == 0)
- {
- size_t bufsize = sizeof(buff);
- if (gnutls_x509_crt_get_dn(gcert, CS buff, &bufsize) >= 0)
- dn_string = string_copy_malloc(buff);
- }
+ gnutls_session_ticket_key_generate(&server_sessticket_key); /* >= 2.10.0 */
+ if (f.running_in_test_harness) ssl_session_timeout = 6;
+#endif
- verify = gnutls_certificate_verify_peers(session);
+ tls_daemon_creds_reload();
}
+}
+
+/* ------------------------------------------------------------------------ */
+
+/*************************************************
+* Deal with logging errors during I/O *
+*************************************************/
+
+/* We have to get the identity of the peer from saved data.
+
+Argument:
+ state the current GnuTLS exim state container
+ rc the GnuTLS error code, or 0 if it's a local error
+ when text identifying read or write
+ text local error text when rc is 0
+
+Returns: nothing
+*/
+
+static void
+record_io_error(exim_gnutls_state_st *state, int rc, uschar *when, uschar *text)
+{
+const uschar * msg;
+uschar * errstr;
+
+msg = rc == GNUTLS_E_FATAL_ALERT_RECEIVED
+ ? string_sprintf("A TLS fatal alert has been received: %s",
+ US gnutls_alert_get_name(gnutls_alert_get(state->session)))
+#ifdef GNUTLS_E_PREMATURE_TERMINATION
+ : rc == GNUTLS_E_PREMATURE_TERMINATION && errno
+ ? string_sprintf("%s: syscall: %s", US gnutls_strerror(rc), strerror(errno))
+#endif
+ : US gnutls_strerror(rc);
+
+(void) tls_error(when, msg, state->host, &errstr);
+
+if (state->host)
+ log_write(0, LOG_MAIN, "H=%s [%s] TLS error on connection %s",
+ state->host->name, state->host->address, errstr);
else
{
- DEBUG(D_tls) debug_printf("no peer certificate supplied\n");
- verify = GNUTLS_CERT_INVALID;
- *error = US"not supplied";
+ uschar * conn_info = smtp_get_connection_info();
+ if (Ustrncmp(conn_info, US"SMTP ", 5) == 0) conn_info += 5;
+ /* I'd like to get separated H= here, but too hard for now */
+ log_write(0, LOG_MAIN, "TLS error on %s %s", conn_info, errstr);
}
+}
+
+
+
+
+/*************************************************
+* Set various Exim expansion vars *
+*************************************************/
+
+#define exim_gnutls_cert_err(Label) \
+ do \
+ { \
+ if (rc != GNUTLS_E_SUCCESS) \
+ { \
+ DEBUG(D_tls) debug_printf("TLS: cert problem: %s: %s\n", \
+ (Label), gnutls_strerror(rc)); \
+ return rc; \
+ } \
+ } while (0)
+
+static int
+import_cert(const gnutls_datum_t * cert, gnutls_x509_crt_t * crtp)
+{
+int rc;
+
+rc = gnutls_x509_crt_init(crtp);
+exim_gnutls_cert_err(US"gnutls_x509_crt_init (crt)");
+
+rc = gnutls_x509_crt_import(*crtp, cert, GNUTLS_X509_FMT_DER);
+exim_gnutls_cert_err(US"failed to import certificate [gnutls_x509_crt_import(cert)]");
-/* Handle the result of verification. INVALID seems to be set as well
-as REVOKED, but leave the test for both. */
+return rc;
+}
+
+#undef exim_gnutls_cert_err
+
+
+/* We set various Exim global variables from the state, once a session has
+been established. With TLS callouts, may need to change this to stack
+variables, or just re-call it with the server state after client callout
+has finished.
+
+Make sure anything set here is unset in tls_getc().
+
+Sets:
+ tls_active fd
+ tls_bits strength indicator
+ tls_certificate_verified bool indicator
+ tls_channelbinding for some SASL mechanisms
+ tls_ver a string
+ tls_cipher a string
+ tls_peercert pointer to library internal
+ tls_peerdn a string
+ tls_sni a (UTF-8) string
+ tls_ourcert pointer to library internal
+
+Argument:
+ state the relevant exim_gnutls_state_st *
+*/
+
+static void
+extract_exim_vars_from_tls_state(exim_gnutls_state_st * state)
+{
+tls_support * tlsp = state->tlsp;
+
+tlsp->active.sock = state->fd_out;
+tlsp->active.tls_ctx = state;
+
+DEBUG(D_tls) debug_printf("cipher: %s\n", state->ciphersuite);
+
+tlsp->certificate_verified = state->peer_cert_verified;
+#ifdef SUPPORT_DANE
+tlsp->dane_verified = state->peer_dane_verified;
+#endif
+
+/* note that tls_channelbinding is not saved to the spool file, since it's
+only available for use for authenticators while this TLS session is running. */
-if ((verify & (GNUTLS_CERT_INVALID|GNUTLS_CERT_REVOKED)) != 0)
+tlsp->channelbinding = NULL;
+#ifdef HAVE_GNUTLS_SESSION_CHANNEL_BINDING
{
- tls_certificate_verified = FALSE;
- if (*error == NULL) *error = ((verify & GNUTLS_CERT_REVOKED) != 0)?
- US"revoked" : US"invalid";
- if (verify_requirement == VERIFY_REQUIRED)
+ gnutls_datum_t channel = {.data = NULL, .size = 0};
+ int rc;
+
+# ifdef HAVE_GNUTLS_EXPORTER
+ if (gnutls_protocol_get_version(state->session) >= GNUTLS_TLS1_3)
+ {
+ rc = gnutls_session_channel_binding(state->session, GNUTLS_CB_TLS_EXPORTER, &channel);
+ tlsp->channelbind_exporter = TRUE;
+ }
+ else
+# elif defined(HAVE_GNUTLS_PRF_RFC5705)
+ /* Older libraries may not have GNUTLS_TLS1_3 defined! */
+ if (gnutls_protocol_get_version(state->session) > GNUTLS_TLS1_2)
+ {
+ uschar * buf = store_get(32, state->host ? GET_TAINTED : GET_UNTAINTED);
+ rc = gnutls_prf_rfc5705(state->session,
+ (size_t)24, "EXPORTER-Channel-Binding", (size_t)0, "",
+ 32, CS buf);
+ channel.data = buf;
+ channel.size = 32;
+ }
+ else
+# endif
+ rc = gnutls_session_channel_binding(state->session, GNUTLS_CB_TLS_UNIQUE, &channel);
+
+ if (rc)
+ { DEBUG(D_tls) debug_printf("extracting channel binding: %s\n", gnutls_strerror(rc)); }
+ else
{
- DEBUG(D_tls) debug_printf("TLS certificate verification failed (%s): "
- "peerdn=%s\n", *error, dn_string);
- gnutls_alert_send(session, GNUTLS_AL_FATAL, GNUTLS_A_BAD_CERTIFICATE);
- return FALSE; /* reject */
+ int old_pool = store_pool;
+ /* Declare the taintedness of the binding info. On server, untainted; on
+ client, tainted if we used the Finish msg from the server. */
+
+ store_pool = POOL_PERM;
+ tlsp->channelbinding = b64encode_taint(CUS channel.data, (int)channel.size,
+ !tlsp->channelbind_exporter && state->host ? GET_TAINTED : GET_UNTAINTED);
+ store_pool = old_pool;
+ DEBUG(D_tls) debug_printf("Have channel bindings cached for possible auth usage\n");
}
- DEBUG(D_tls) debug_printf("TLS certificate verify failure (%s) overridden "
- "(host in tls_try_verify_hosts): peerdn=%s\n", *error, dn_string);
}
-else
+#endif
+
+/* peercert is set in peer_status() */
+tlsp->peerdn = state->peerdn;
+
+/* do not corrupt sni sent by client; record sni rxd by server */
+if (!state->host)
+ tlsp->sni = state->received_sni;
+
+/* record our certificate */
{
- tls_certificate_verified = TRUE;
- DEBUG(D_tls) debug_printf("TLS certificate verified: peerdn=%s\n",
- dn_string);
- }
+ const gnutls_datum_t * cert = gnutls_certificate_get_ours(state->session);
+ gnutls_x509_crt_t crt;
-tls_peerdn = dn_string;
-return TRUE; /* accept */
+ tlsp->ourcert = cert && import_cert(cert, &crt)==0 ? crt : NULL;
+ }
}
+
/*************************************************
* Setup up DH parameters *
*************************************************/
waste a bit of effort, but it doesn't seem worth messing around with locking to
prevent this.
-Argument:
- host NULL for server, server for client (for error handling)
-
Returns: OK/DEFER/FAIL
*/
static int
-init_dh(host_item *host)
+init_server_dh(uschar ** errstr)
{
-int fd;
-int ret;
-gnutls_datum m;
-uschar filename[200];
+int fd, rc;
+unsigned int dh_bits;
+gnutls_datum_t m;
+uschar filename_buf[PATH_MAX];
+uschar *filename = NULL;
+size_t sz;
+uschar *exp_tls_dhparam;
+BOOL use_file_in_spool = FALSE;
+host_item *host = NULL; /* dummy for macros */
+
+DEBUG(D_tls) debug_printf("Initialising GnuTLS server params\n");
+
+if ((rc = gnutls_dh_params_init(&dh_server_params)))
+ return tls_error_gnu(NULL, US"gnutls_dh_params_init", rc, errstr);
+
+m.data = NULL;
+m.size = 0;
+
+if (!expand_check(tls_dhparam, US"tls_dhparam", &exp_tls_dhparam, errstr))
+ return DEFER;
+
+if (!exp_tls_dhparam)
+ {
+ DEBUG(D_tls) debug_printf("Loading default hard-coded DH params\n");
+ m.data = US std_dh_prime_default();
+ m.size = Ustrlen(m.data);
+ }
+else if (Ustrcmp(exp_tls_dhparam, "historic") == 0)
+ use_file_in_spool = TRUE;
+else if (Ustrcmp(exp_tls_dhparam, "none") == 0)
+ {
+ DEBUG(D_tls) debug_printf("Requested no DH parameters\n");
+ return OK;
+ }
+else if (exp_tls_dhparam[0] != '/')
+ {
+ if (!(m.data = US std_dh_prime_named(exp_tls_dhparam)))
+ return tls_error(US"No standard prime named", exp_tls_dhparam, NULL, errstr);
+ m.size = Ustrlen(m.data);
+ }
+else
+ filename = exp_tls_dhparam;
+
+if (m.data)
+ {
+ if ((rc = gnutls_dh_params_import_pkcs3(dh_server_params, &m, GNUTLS_X509_FMT_PEM)))
+ return tls_error_gnu(NULL, US"gnutls_dh_params_import_pkcs3", rc, errstr);
+ DEBUG(D_tls) debug_printf("Loaded fixed standard D-H parameters\n");
+ return OK;
+ }
-/* Initialize the data structures for holding the parameters */
+#ifdef HAVE_GNUTLS_SEC_PARAM_CONSTANTS
+/* If you change this constant, also change dh_param_fn_ext so that we can use a
+different filename and ensure we have sufficient bits. */
-ret = gnutls_dh_params_init(&dh_params);
-if (ret < 0) return tls_error(US"init dh_params", host, ret);
+if (!(dh_bits = gnutls_sec_param_to_pk_bits(GNUTLS_PK_DH, GNUTLS_SEC_PARAM_NORMAL)))
+ return tls_error(US"gnutls_sec_param_to_pk_bits() failed", NULL, NULL, errstr);
+DEBUG(D_tls)
+ debug_printf("GnuTLS tells us that for D-H PK, NORMAL is %d bits\n",
+ dh_bits);
+#else
+dh_bits = EXIM_SERVER_DH_BITS_PRE2_12;
+DEBUG(D_tls)
+ debug_printf("GnuTLS lacks gnutls_sec_param_to_pk_bits(), using %d bits\n",
+ dh_bits);
+#endif
-/* Set up the name of the cache file */
+/* Some clients have hard-coded limits. */
+if (dh_bits > tls_dh_max_bits)
+ {
+ DEBUG(D_tls)
+ debug_printf("tls_dh_max_bits clamping override, using %d bits instead\n",
+ tls_dh_max_bits);
+ dh_bits = tls_dh_max_bits;
+ }
-if (!string_format(filename, sizeof(filename), "%s/gnutls-params",
- spool_directory))
- return tls_error(US"overlong filename", host, 0);
+if (use_file_in_spool)
+ {
+ if (!string_format(filename_buf, sizeof(filename_buf),
+ "%s/gnutls-params-%d", spool_directory, dh_bits))
+ return tls_error(US"overlong filename", NULL, NULL, errstr);
+ filename = filename_buf;
+ }
/* Open the cache file for reading and if successful, read it and set up the
parameters. */
-fd = Uopen(filename, O_RDONLY, 0);
-if (fd >= 0)
+if ((fd = Uopen(filename, O_RDONLY, 0)) >= 0)
{
struct stat statbuf;
- if (fstat(fd, &statbuf) < 0)
+ FILE *fp;
+ int saved_errno;
+
+ if (fstat(fd, &statbuf) < 0) /* EIO */
+ {
+ saved_errno = errno;
+ (void)close(fd);
+ return tls_error_sys(US"TLS cache stat failed", saved_errno, NULL, errstr);
+ }
+ if (!S_ISREG(statbuf.st_mode))
{
(void)close(fd);
- return tls_error(US"TLS cache stat failed", host, 0);
+ return tls_error(US"TLS cache not a file", NULL, NULL, errstr);
+ }
+ if (!(fp = fdopen(fd, "rb")))
+ {
+ saved_errno = errno;
+ (void)close(fd);
+ return tls_error_sys(US"fdopen(TLS cache stat fd) failed",
+ saved_errno, NULL, errstr);
}
m.size = statbuf.st_size;
- m.data = malloc(m.size);
- if (m.data == NULL)
- return tls_error(US"memory allocation failed", host, 0);
- if (read(fd, m.data, m.size) != m.size)
- return tls_error(US"TLS cache read failed", host, 0);
- (void)close(fd);
-
- ret = gnutls_dh_params_import_pkcs3(dh_params, &m, GNUTLS_X509_FMT_PEM);
- if (ret < 0) return tls_error(US"DH params import", host, ret);
- DEBUG(D_tls) debug_printf("read D-H parameters from file\n");
+ if (!(m.data = store_malloc(m.size)))
+ {
+ fclose(fp);
+ return tls_error_sys(US"malloc failed", errno, NULL, errstr);
+ }
+ if (!(sz = fread(m.data, m.size, 1, fp)))
+ {
+ saved_errno = errno;
+ fclose(fp);
+ store_free(m.data);
+ return tls_error_sys(US"fread failed", saved_errno, NULL, errstr);
+ }
+ fclose(fp);
- free(m.data);
+ rc = gnutls_dh_params_import_pkcs3(dh_server_params, &m, GNUTLS_X509_FMT_PEM);
+ store_free(m.data);
+ if (rc)
+ return tls_error_gnu(NULL, US"gnutls_dh_params_import_pkcs3", rc, errstr);
+ DEBUG(D_tls) debug_printf("read D-H parameters from file \"%s\"\n", filename);
}
/* If the file does not exist, fall through to compute new data and cache it.
else if (errno == ENOENT)
{
- ret = -1;
+ rc = -1;
DEBUG(D_tls)
- debug_printf("parameter cache file %s does not exist\n", filename);
+ debug_printf("D-H parameter cache file \"%s\" does not exist\n", filename);
}
else
- return tls_error(string_open_failed(errno, "%s for reading", filename),
- host, 0);
+ return tls_error(string_open_failed("\"%s\" for reading", filename),
+ NULL, NULL, errstr);
/* If ret < 0, either the cache file does not exist, or the data it contains
is not useful. One particular case of this is when upgrading from an older
try to be clever and support both formats; we just regenerate new data in this
case. */
-if (ret < 0)
+if (rc < 0)
{
- uschar tempfilename[sizeof(filename) + 10];
-
- DEBUG(D_tls) debug_printf("generating %d bit Diffie-Hellman key...\n",
- DH_BITS);
- ret = gnutls_dh_params_generate2(dh_params, DH_BITS);
- if (ret < 0) return tls_error(US"D-H key generation", host, ret);
-
- /* Write the parameters to a file in the spool directory so that we
- can use them from other Exim processes. */
-
- sprintf(CS tempfilename, "%s-%d", filename, (int)getpid());
- fd = Uopen(tempfilename, O_WRONLY|O_CREAT, 0400);
- if (fd < 0)
- return tls_error(string_open_failed(errno, "%s for writing", filename),
- host, 0);
- (void)fchown(fd, exim_uid, exim_gid); /* Probably not necessary */
-
- /* export the parameters in a format that can be generated using GNUTLS'
- * certtool or other programs.
- *
- * The commands for certtool are:
- * $ certtool --generate-dh-params --bits 1024 > params
+ uschar *temp_fn;
+ unsigned int dh_bits_gen = dh_bits;
+
+ if ((PATH_MAX - Ustrlen(filename)) < 10)
+ return tls_error(US"Filename too long to generate replacement",
+ filename, NULL, errstr);
+
+ temp_fn = string_copy(US"exim-dh.XXXXXXX");
+ if ((fd = mkstemp(CS temp_fn)) < 0) /* modifies temp_fn */
+ return tls_error_sys(US"Unable to open temp file", errno, NULL, errstr);
+ (void)exim_chown(temp_fn, exim_uid, exim_gid); /* Probably not necessary */
+
+ /* GnuTLS overshoots!
+ * If we ask for 2236, we might get 2237 or more.
+ * But there's no way to ask GnuTLS how many bits there really are.
+ * We can ask how many bits were used in a TLS session, but that's it!
+ * The prime itself is hidden behind too much abstraction.
+ * So we ask for less, and proceed on a wing and a prayer.
+ * First attempt, subtracted 3 for 2233 and got 2240.
*/
+ if (dh_bits >= EXIM_CLIENT_DH_MIN_BITS + 10)
+ {
+ dh_bits_gen = dh_bits - 10;
+ DEBUG(D_tls)
+ debug_printf("being paranoid about DH generation, make it '%d' bits'\n",
+ dh_bits_gen);
+ }
- m.size = PARAM_SIZE;
- m.data = malloc(m.size);
- if (m.data == NULL)
- return tls_error(US"memory allocation failed", host, 0);
-
- m.size = PARAM_SIZE;
- ret = gnutls_dh_params_export_pkcs3(dh_params, GNUTLS_X509_FMT_PEM, m.data,
- &m.size);
- if (ret < 0) return tls_error(US"DH params export", host, ret);
+ DEBUG(D_tls)
+ debug_printf("requesting generation of %d bit Diffie-Hellman prime ...\n",
+ dh_bits_gen);
+ if ((rc = gnutls_dh_params_generate2(dh_server_params, dh_bits_gen)))
+ return tls_error_gnu(NULL, US"gnutls_dh_params_generate2", rc, errstr);
+
+ /* gnutls_dh_params_export_pkcs3() will tell us the exact size, every time,
+ and I confirmed that a NULL call to get the size first is how the GnuTLS
+ sample apps handle this. */
+
+ sz = 0;
+ m.data = NULL;
+ if ( (rc = gnutls_dh_params_export_pkcs3(dh_server_params,
+ GNUTLS_X509_FMT_PEM, m.data, &sz))
+ && rc != GNUTLS_E_SHORT_MEMORY_BUFFER)
+ return tls_error_gnu(NULL, US"gnutls_dh_params_export_pkcs3(NULL) sizing",
+ rc, errstr);
+ m.size = sz;
+ if (!(m.data = store_malloc(m.size)))
+ return tls_error_sys(US"memory allocation failed", errno, NULL, errstr);
+
+ /* this will return a size 1 less than the allocation size above */
+ if ((rc = gnutls_dh_params_export_pkcs3(dh_server_params, GNUTLS_X509_FMT_PEM,
+ m.data, &sz)))
+ {
+ store_free(m.data);
+ return tls_error_gnu(NULL, US"gnutls_dh_params_export_pkcs3() real", rc, errstr);
+ }
+ m.size = sz; /* shrink by 1, probably */
- m.size = Ustrlen(m.data);
- if (write(fd, m.data, m.size) != m.size || write(fd, "\n", 1) != 1)
- return tls_error(US"TLS cache write failed", host, 0);
+ if ((sz = write_to_fd_buf(fd, m.data, (size_t) m.size)) != m.size)
+ {
+ store_free(m.data);
+ return tls_error_sys(US"TLS cache write D-H params failed",
+ errno, NULL, errstr);
+ }
+ store_free(m.data);
+ if ((sz = write_to_fd_buf(fd, US"\n", 1)) != 1)
+ return tls_error_sys(US"TLS cache write D-H params final newline failed",
+ errno, NULL, errstr);
- free(m.data);
- (void)close(fd);
+ if ((rc = close(fd)))
+ return tls_error_sys(US"TLS cache write close() failed", errno, NULL, errstr);
- if (rename(CS tempfilename, CS filename) < 0)
- return tls_error(string_sprintf("failed to rename %s as %s: %s",
- tempfilename, filename, strerror(errno)), host, 0);
+ if (Urename(temp_fn, filename) < 0)
+ return tls_error_sys(string_sprintf("failed to rename \"%s\" as \"%s\"",
+ temp_fn, filename), errno, NULL, errstr);
- DEBUG(D_tls) debug_printf("wrote D-H parameters to file %s\n", filename);
+ DEBUG(D_tls) debug_printf("wrote D-H parameters to file \"%s\"\n", filename);
}
-DEBUG(D_tls) debug_printf("initialized D-H parameters\n");
+DEBUG(D_tls) debug_printf("initialized server D-H parameters\n");
return OK;
}
-/*************************************************
-* Initialize for GnuTLS *
-*************************************************/
-
-/* Called from both server and client code. In the case of a server, errors
-before actual TLS negotiation return DEFER.
-
-Arguments:
- host connected host, if client; NULL if server
- certificate certificate file
- privatekey private key file
- cas CA certs file
- crl CRL file
-
-Returns: OK/DEFER/FAIL
-*/
+/* Create and install a selfsigned certificate, for use in server mode. */
static int
-tls_init(host_item *host, uschar *certificate, uschar *privatekey, uschar *cas,
- uschar *crl)
+tls_install_selfsign(exim_gnutls_state_st * state, uschar ** errstr)
{
+gnutls_x509_crt_t cert = NULL;
+time_t now;
+gnutls_x509_privkey_t pkey = NULL;
+const uschar * where;
int rc;
-uschar *cert_expanded, *key_expanded, *cas_expanded, *crl_expanded;
-initialized = (host == NULL)? INITIALIZED_SERVER : INITIALIZED_CLIENT;
+#ifndef SUPPORT_SELFSIGN
+where = US"library too old";
+rc = GNUTLS_E_NO_CERTIFICATE_FOUND;
+if (TRUE) goto err;
+#endif
+
+DEBUG(D_tls) debug_printf("TLS: generating selfsigned server cert\n");
+where = US"initialising pkey";
+if ((rc = gnutls_x509_privkey_init(&pkey))) goto err;
+
+where = US"initialising cert";
+if ((rc = gnutls_x509_crt_init(&cert))) goto err;
+
+where = US"generating pkey"; /* Hangs on 2.12.23 */
+if ((rc = gnutls_x509_privkey_generate(pkey, GNUTLS_PK_RSA,
+#ifdef SUPPORT_PARAM_TO_PK_BITS
+# ifndef GNUTLS_SEC_PARAM_MEDIUM
+# define GNUTLS_SEC_PARAM_MEDIUM GNUTLS_SEC_PARAM_HIGH
+# endif
+ gnutls_sec_param_to_pk_bits(GNUTLS_PK_RSA, GNUTLS_SEC_PARAM_MEDIUM),
+#else
+ 2048,
+#endif
+ 0)))
+ goto err;
+
+where = US"configuring cert";
+now = 1;
+if ( (rc = gnutls_x509_crt_set_version(cert, 3))
+ || (rc = gnutls_x509_crt_set_serial(cert, &now, sizeof(now)))
+ || (rc = gnutls_x509_crt_set_activation_time(cert, now = time(NULL)))
+ || (rc = gnutls_x509_crt_set_expiration_time(cert, (long)2 * 60 * 60)) /* 2 hour */
+ || (rc = gnutls_x509_crt_set_key(cert, pkey))
+
+ || (rc = gnutls_x509_crt_set_dn_by_oid(cert,
+ GNUTLS_OID_X520_COUNTRY_NAME, 0, "UK", 2))
+ || (rc = gnutls_x509_crt_set_dn_by_oid(cert,
+ GNUTLS_OID_X520_ORGANIZATION_NAME, 0, "Exim Developers", 15))
+ || (rc = gnutls_x509_crt_set_dn_by_oid(cert,
+ GNUTLS_OID_X520_COMMON_NAME, 0,
+ smtp_active_hostname, Ustrlen(smtp_active_hostname)))
+ )
+ goto err;
+
+where = US"signing cert";
+if ((rc = gnutls_x509_crt_sign(cert, cert, pkey))) goto err;
+
+where = US"installing selfsign cert";
+ /* Since: 2.4.0 */
+if ((rc = gnutls_certificate_set_x509_key(state->lib_state.x509_cred,
+ &cert, 1, pkey)))
+ goto err;
+
+rc = OK;
+
+out:
+ if (cert) gnutls_x509_crt_deinit(cert);
+ if (pkey) gnutls_x509_privkey_deinit(pkey);
+ return rc;
+
+err:
+ rc = tls_error_gnu(state, where, rc, errstr);
+ goto out;
+}
+
-rc = gnutls_global_init();
-if (rc < 0) return tls_error(US"tls-init", host, rc);
-/* Create D-H parameters, or read them from the cache file. This function does
-its own SMTP error messaging. */
-rc = init_dh(host);
-if (rc != OK) return rc;
+/* Add certificate and key, from files.
+
+Return:
+ Zero or negative: good. Negate value for certificate index if < 0.
+ Greater than zero: FAIL or DEFER code.
+*/
-/* Create the credentials structure */
+static int
+tls_add_certfile(exim_gnutls_state_st * state, const host_item * host,
+ const uschar * certfile, const uschar * keyfile, uschar ** errstr)
+{
+int rc = gnutls_certificate_set_x509_key_file(state->lib_state.x509_cred,
+ CCS certfile, CCS keyfile, GNUTLS_X509_FMT_PEM);
+if (rc < 0)
+ return tls_error_gnu(state,
+ string_sprintf("cert/key setup: cert=%s key=%s", certfile, keyfile),
+ rc, errstr);
+return -rc;
+}
-rc = gnutls_certificate_allocate_credentials(&x509_cred);
-if (rc < 0) return tls_error(US"certificate_allocate_credentials", host, rc);
-/* This stuff must be done for each session, because different certificates
-may be required for different sessions. */
+#if !defined(DISABLE_OCSP) && !defined(SUPPORT_GNUTLS_EXT_RAW_PARSE)
+/* Load an OCSP proof from file for sending by the server. Called
+on getting a status-request handshake message, for earlier versions
+of GnuTLS. */
-if (!expand_check(certificate, US"tls_certificate", &cert_expanded))
- return DEFER;
+static int
+server_ocsp_stapling_cb(gnutls_session_t session, void * ptr,
+ gnutls_datum_t * ocsp_response)
+{
+int ret;
+DEBUG(D_tls) debug_printf("OCSP stapling callback: %s\n", US ptr);
-key_expanded = NULL;
-if (privatekey != NULL)
+if ((ret = gnutls_load_file(ptr, ocsp_response)) < 0)
{
- if (!expand_check(privatekey, US"tls_privatekey", &key_expanded))
- return DEFER;
+ DEBUG(D_tls) debug_printf("Failed to load ocsp stapling file %s\n",
+ CS ptr);
+ tls_in.ocsp = OCSP_NOT_RESP;
+ return GNUTLS_E_NO_CERTIFICATE_STATUS;
}
-/* If expansion was forced to fail, key_expanded will be NULL. If the result of
-the expansion is an empty string, ignore it also, and assume that the private
-key is in the same file as the certificate. */
-
-if (key_expanded == NULL || *key_expanded == 0)
- key_expanded = cert_expanded;
+tls_in.ocsp = OCSP_VFY_NOT_TRIED;
+return 0;
+}
+#endif
-/* Set the certificate and private keys */
-if (cert_expanded != NULL)
+#ifdef SUPPORT_GNUTLS_EXT_RAW_PARSE
+/* Make a note that we saw a status-request */
+static int
+tls_server_clienthello_ext(void * ctx, unsigned tls_id,
+ const uschar * data, unsigned size)
+{
+/* The values for tls_id are documented here:
+https://www.iana.org/assignments/tls-extensiontype-values/tls-extensiontype-values.xhtml */
+switch (tls_id)
{
- DEBUG(D_tls) debug_printf("certificate file = %s\nkey file = %s\n",
- cert_expanded, key_expanded);
- rc = gnutls_certificate_set_x509_key_file(x509_cred, CS cert_expanded,
- CS key_expanded, GNUTLS_X509_FMT_PEM);
- if (rc < 0)
- {
- uschar *msg = string_sprintf("cert/key setup: cert=%s key=%s",
- cert_expanded, key_expanded);
- return tls_error(msg, host, rc);
- }
+ case 5: /* Status Request */
+ DEBUG(D_tls) debug_printf("Seen status_request extension from client\n");
+ tls_in.ocsp = OCSP_NOT_RESP;
+ break;
+#ifdef EXIM_HAVE_ALPN
+ case 16: /* Application Layer Protocol Notification */
+ /* The format of "data" here doesn't seem to be documented, but appears
+ to be a 2-byte field with a (redundant, given the "size" arg) total length
+ then a sequence of one-byte size then string (not nul-term) names. The
+ latter is as described in OpenSSL documentation. */
+
+ DEBUG(D_tls) debug_printf("Seen ALPN extension from client (s=%u):", size);
+ for (const uschar * s = data+2; s-data < size-1; s += *s + 1)
+ {
+ server_seen_alpn++;
+ DEBUG(D_tls) debug_printf(" '%.*s'", (int)*s, s+1);
+ }
+ DEBUG(D_tls) debug_printf("\n");
+ if (server_seen_alpn > 1)
+ {
+ DEBUG(D_tls) debug_printf("TLS: too many ALPNs presented in handshake\n");
+ return GNUTLS_E_NO_APPLICATION_PROTOCOL;
+ }
+ break;
+#endif
}
+return 0;
+}
-/* A certificate is mandatory in a server, but not in a client */
+/* Callback for client-hello, on server, if we think we might serve stapled-OCSP */
+static int
+tls_server_clienthello_cb(gnutls_session_t session, unsigned int htype,
+ unsigned when, unsigned int incoming, const gnutls_datum_t * msg)
+{
+/* Call fn for each extension seen. 3.6.3 onwards */
+int rc = gnutls_ext_raw_parse(NULL, tls_server_clienthello_ext, msg,
+ GNUTLS_EXT_RAW_FLAG_TLS_CLIENT_HELLO);
+return rc == GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE ? 0 : rc;
+}
-else
+
+# ifdef notdef_crashes
+/* Make a note that we saw a status-response */
+static int
+tls_server_servercerts_ext(void * ctx, unsigned tls_id,
+ const unsigned char *data, unsigned size)
+{
+/* debug_printf("%s %u\n", __FUNCTION__, tls_id); */
+/* https://www.iana.org/assignments/tls-extensiontype-values/tls-extensiontype-values.xhtml */
+if (FALSE && tls_id == 5) /* status_request */
{
- if (host == NULL)
- return tls_error(US"no TLS server certificate is specified", host, 0);
- DEBUG(D_tls) debug_printf("no TLS client certificate is specified\n");
+ DEBUG(D_tls) debug_printf("Seen status_request extension\n");
+ tls_in.ocsp = exim_testharness_disable_ocsp_validity_check
+ ? OCSP_VFY_NOT_TRIED : OCSP_VFIED; /* We know that GnuTLS verifies responses */
}
+return 0;
+}
+# endif
-/* Set the trusted CAs file if one is provided, and then add the CRL if one is
-provided. Experiment shows that, if the certificate file is empty, an unhelpful
-error message is provided. However, if we just refrain from setting anything up
-in that case, certificate verification fails, which seems to be the correct
-behaviour. */
+/* Callback for certificates packet, on server, if we think we might serve stapled-OCSP */
+static int
+tls_server_servercerts_cb(gnutls_session_t session, unsigned int htype,
+ unsigned when, unsigned int incoming, const gnutls_datum_t * msg)
+{
+/* Call fn for each extension seen. 3.6.3 onwards */
+# ifdef notdef_crashes
+ /*XXX crashes */
+return gnutls_ext_raw_parse(NULL, tls_server_servercerts_ext, msg, 0);
+# endif
+}
+#endif /*SUPPORT_GNUTLS_EXT_RAW_PARSE*/
+
+/*XXX in tls1.3 the cert-status travel as an extension next to the cert, in the
+ "Handshake Protocol: Certificate" record.
+So we need to spot the Certificate handshake message, parse it and spot any status_request extension(s)
+
+This is different to tls1.2 - where it is a separate record (wireshark term) / handshake message (gnutls term).
+*/
+
+#if defined(EXIM_HAVE_TLS_RESUME) || defined(SUPPORT_GNUTLS_EXT_RAW_PARSE)
+/* Callback for certificate-status, on server. We sent stapled OCSP. */
+static int
+tls_server_certstatus_cb(gnutls_session_t session, unsigned int htype,
+ unsigned when, unsigned int incoming, const gnutls_datum_t * msg)
+{
+DEBUG(D_tls) debug_printf("Sending certificate-status\n"); /*XXX we get this for tls1.2 but not for 1.3 */
+# ifdef SUPPORT_SRV_OCSP_STACK
+tls_in.ocsp = exim_testharness_disable_ocsp_validity_check
+ ? OCSP_VFY_NOT_TRIED : OCSP_VFIED; /* We know that GnuTLS verifies responses */
+# else
+tls_in.ocsp = OCSP_VFY_NOT_TRIED;
+# endif
+return 0;
+}
-if (cas != NULL)
+/* Callback for handshake messages, on server */
+static int
+tls_server_hook_cb(gnutls_session_t sess, u_int htype, unsigned when,
+ unsigned incoming, const gnutls_datum_t * msg)
+{
+/* debug_printf("%s: htype %u\n", __FUNCTION__, htype); */
+switch (htype)
{
- struct stat statbuf;
+# ifdef SUPPORT_GNUTLS_EXT_RAW_PARSE
+ case GNUTLS_HANDSHAKE_CLIENT_HELLO:
+ return tls_server_clienthello_cb(sess, htype, when, incoming, msg);
+ case GNUTLS_HANDSHAKE_CERTIFICATE_PKT:
+ return tls_server_servercerts_cb(sess, htype, when, incoming, msg);
+# endif
+ case GNUTLS_HANDSHAKE_CERTIFICATE_STATUS:
+ return tls_server_certstatus_cb(sess, htype, when, incoming, msg);
+# ifdef EXIM_HAVE_TLS_RESUME
+ case GNUTLS_HANDSHAKE_NEW_SESSION_TICKET:
+ return tls_server_ticket_cb(sess, htype, when, incoming, msg);
+# endif
+ default:
+ return 0;
+ }
+}
+#endif
- if (!expand_check(cas, US"tls_verify_certificates", &cas_expanded))
- return DEFER;
- if (stat(CS cas_expanded, &statbuf) < 0)
+#if !defined(DISABLE_OCSP) && defined(SUPPORT_GNUTLS_EXT_RAW_PARSE)
+static void
+tls_server_testharness_ocsp_fiddle(void)
+{
+extern char ** environ;
+if (environ) for (uschar ** p = USS environ; *p; p++)
+ if (Ustrncmp(*p, "EXIM_TESTHARNESS_DISABLE_OCSPVALIDITYCHECK", 42) == 0)
{
- log_write(0, LOG_MAIN|LOG_PANIC, "could not stat %s "
- "(tls_verify_certificates): %s", cas_expanded, strerror(errno));
- return DEFER;
+ DEBUG(D_tls) debug_printf("Permitting known bad OCSP response\n");
+ exim_testharness_disable_ocsp_validity_check = TRUE;
}
+}
+#endif
- DEBUG(D_tls) debug_printf("verify certificates = %s size=" OFF_T_FMT "\n",
- cas_expanded, statbuf.st_size);
+/**************************************************
+* One-time init credentials for server and client *
+**************************************************/
- /* If the cert file is empty, there's no point in loading the CRL file. */
+static void
+creds_basic_init(gnutls_certificate_credentials_t x509_cred, BOOL server)
+{
+#ifdef SUPPORT_SRV_OCSP_STACK
+gnutls_certificate_set_flags(x509_cred, GNUTLS_CERTIFICATE_API_V2);
- if (statbuf.st_size > 0)
- {
- rc = gnutls_certificate_set_x509_trust_file(x509_cred, CS cas_expanded,
- GNUTLS_X509_FMT_PEM);
- if (rc < 0) return tls_error(US"setup_certs", host, rc);
+# if !defined(DISABLE_OCSP) && defined(SUPPORT_GNUTLS_EXT_RAW_PARSE)
+if (server && tls_ocsp_file)
+ {
+ if (f.running_in_test_harness)
+ tls_server_testharness_ocsp_fiddle();
+
+ if (exim_testharness_disable_ocsp_validity_check)
+ gnutls_certificate_set_flags(x509_cred,
+ GNUTLS_CERTIFICATE_API_V2 | GNUTLS_CERTIFICATE_SKIP_OCSP_RESPONSE_CHECK);
+ }
+# endif
+#endif
+DEBUG(D_tls)
+ debug_printf("TLS: basic cred init, %s\n", server ? "server" : "client");
+}
+
+static int
+creds_load_server_certs(exim_gnutls_state_st * state, const uschar * cert,
+ const uschar * pkey, const uschar * ocsp, uschar ** errstr)
+{
+const uschar * clist = cert;
+const uschar * klist = pkey;
+const uschar * olist;
+int csep = 0, ksep = 0, osep = 0, cnt = 0, rc;
+uschar * cfile, * kfile, * ofile;
+#ifndef DISABLE_OCSP
+# ifdef SUPPORT_GNUTLS_EXT_RAW_PARSE
+gnutls_x509_crt_fmt_t ocsp_fmt = GNUTLS_X509_FMT_DER;
+# endif
+
+if (!expand_check(ocsp, US"tls_ocsp_file", &ofile, errstr))
+ return DEFER;
+olist = ofile;
+#endif
+
+while (cfile = string_nextinlist(&clist, &csep, NULL, 0))
+
+ if (!(kfile = string_nextinlist(&klist, &ksep, NULL, 0)))
+ return tls_error(US"cert/key setup: out of keys", NULL, NULL, errstr);
+ else if ((rc = tls_add_certfile(state, NULL, cfile, kfile, errstr)) > 0)
+ return rc;
+ else
+ {
+ int gnutls_cert_index = -rc;
+ DEBUG(D_tls) debug_printf("TLS: cert/key %d %s registered\n",
+ gnutls_cert_index, cfile);
- if (crl != NULL && *crl != 0)
+#ifndef DISABLE_OCSP
+ if (ocsp)
{
- if (!expand_check(crl, US"tls_crl", &crl_expanded))
- return DEFER;
- DEBUG(D_tls) debug_printf("loading CRL file = %s\n", crl_expanded);
- rc = gnutls_certificate_set_x509_crl_file(x509_cred, CS crl_expanded,
- GNUTLS_X509_FMT_PEM);
- if (rc < 0) return tls_error(US"CRL setup", host, rc);
+ /* Set the OCSP stapling server info */
+ if (gnutls_buggy_ocsp)
+ {
+ DEBUG(D_tls)
+ debug_printf("GnuTLS library is buggy for OCSP; avoiding\n");
+ }
+ else if ((ofile = string_nextinlist(&olist, &osep, NULL, 0)))
+ {
+ DEBUG(D_tls) debug_printf("OCSP response file %d = %s\n",
+ gnutls_cert_index, ofile);
+# ifdef SUPPORT_GNUTLS_EXT_RAW_PARSE
+ if (Ustrncmp(ofile, US"PEM ", 4) == 0)
+ {
+ ocsp_fmt = GNUTLS_X509_FMT_PEM;
+ ofile += 4;
+ }
+ else if (Ustrncmp(ofile, US"DER ", 4) == 0)
+ {
+ ocsp_fmt = GNUTLS_X509_FMT_DER;
+ ofile += 4;
+ }
+
+ if ((rc = gnutls_certificate_set_ocsp_status_request_file2(
+ state->lib_state.x509_cred, CCS ofile, gnutls_cert_index,
+ ocsp_fmt)) < 0)
+ return tls_error_gnu(state,
+ US"gnutls_certificate_set_ocsp_status_request_file2",
+ rc, errstr);
+ DEBUG(D_tls)
+ debug_printf(" %d response%s loaded\n", rc, rc>1 ? "s":"");
+
+ /* Arrange callbacks for OCSP request observability */
+
+ if (state->session)
+ gnutls_handshake_set_hook_function(state->session,
+ GNUTLS_HANDSHAKE_ANY, GNUTLS_HOOK_POST, tls_server_hook_cb);
+ else
+ state->lib_state.ocsp_hook = TRUE;
+
+
+# else
+# if defined(SUPPORT_SRV_OCSP_STACK)
+ if ((rc = gnutls_certificate_set_ocsp_status_request_function2(
+ state->lib_state.x509_cred, gnutls_cert_index,
+ server_ocsp_stapling_cb, ofile)))
+ return tls_error_gnu(state,
+ US"gnutls_certificate_set_ocsp_status_request_function2",
+ rc, errstr);
+ else
+# endif
+ {
+ if (cnt++ > 0)
+ {
+ DEBUG(D_tls)
+ debug_printf("oops; multiple OCSP files not supported\n");
+ break;
+ }
+ gnutls_certificate_set_ocsp_status_request_function(
+ state->lib_state.x509_cred, server_ocsp_stapling_cb, ofile);
+ }
+# endif /* SUPPORT_GNUTLS_EXT_RAW_PARSE */
+ }
+ else
+ DEBUG(D_tls) debug_printf("ran out of OCSP response files in list\n");
}
+#endif /* DISABLE_OCSP */
+ }
+return 0;
+}
+
+static int
+creds_load_client_certs(exim_gnutls_state_st * state, const host_item * host,
+ const uschar * cert, const uschar * pkey, uschar ** errstr)
+{
+int rc = tls_add_certfile(state, host, cert, pkey, errstr);
+if (rc > 0) return rc;
+DEBUG(D_tls) debug_printf("TLS: cert/key registered\n");
+return 0;
+}
+
+static int
+creds_load_cabundle(exim_gnutls_state_st * state, const uschar * bundle,
+ const host_item * host, uschar ** errstr)
+{
+int cert_count;
+struct stat statbuf;
+
+#ifdef SUPPORT_SYSDEFAULT_CABUNDLE
+if (Ustrcmp(bundle, "system") == 0 || Ustrncmp(bundle, "system,", 7) == 0)
+ cert_count = gnutls_certificate_set_x509_system_trust(state->lib_state.x509_cred);
+else
+#endif
+ {
+ if (Ustat(bundle, &statbuf) < 0)
+ {
+ log_write(0, LOG_MAIN|LOG_PANIC, "could not stat '%s' "
+ "(tls_verify_certificates): %s", bundle, strerror(errno));
+ return DEFER;
+ }
+
+#ifndef SUPPORT_CA_DIR
+ /* The test suite passes in /dev/null; we could check for that path explicitly,
+ but who knows if someone has some weird FIFO which always dumps some certs, or
+ other weirdness. The thing we really want to check is that it's not a
+ directory, since while OpenSSL supports that, GnuTLS does not.
+ So s/!S_ISREG/S_ISDIR/ and change some messaging ... */
+ if (S_ISDIR(statbuf.st_mode))
+ {
+ log_write(0, LOG_MAIN|LOG_PANIC,
+ "tls_verify_certificates \"%s\" is a directory", bundle);
+ return DEFER;
+ }
+#endif
+
+ DEBUG(D_tls) debug_printf("verify certificates = %s size=" OFF_T_FMT "\n",
+ bundle, statbuf.st_size);
+
+ if (statbuf.st_size == 0)
+ {
+ DEBUG(D_tls)
+ debug_printf("cert file empty, no certs, no verification, ignoring any CRL\n");
+ return OK;
}
+
+ cert_count =
+
+#ifdef SUPPORT_CA_DIR
+ (statbuf.st_mode & S_IFMT) == S_IFDIR
+ ?
+ gnutls_certificate_set_x509_trust_dir(state->lib_state.x509_cred,
+ CS bundle, GNUTLS_X509_FMT_PEM)
+ :
+#endif
+ gnutls_certificate_set_x509_trust_file(state->lib_state.x509_cred,
+ CS bundle, GNUTLS_X509_FMT_PEM);
+
+#ifdef SUPPORT_CA_DIR
+ /* Mimic the behaviour with OpenSSL of not advertising a usable-cert list
+ when using the directory-of-certs config model. */
+
+ if ((statbuf.st_mode & S_IFMT) == S_IFDIR)
+ if (state->session)
+ gnutls_certificate_send_x509_rdn_sequence(state->session, 1);
+ else
+ state->lib_state.ca_rdn_emulate = TRUE;
+#endif
}
-/* Associate the parameters with the x509 credentials structure. */
+if (cert_count < 0)
+ return tls_error_gnu(state, US"setting certificate trust", cert_count, errstr);
+DEBUG(D_tls)
+ debug_printf("Added %d certificate authorities\n", cert_count);
+
+return OK;
+}
-gnutls_certificate_set_dh_params(x509_cred, dh_params);
-DEBUG(D_tls) debug_printf("initialized certificate stuff\n");
+static int
+creds_load_crl(exim_gnutls_state_st * state, const uschar * crl, uschar ** errstr)
+{
+int cert_count;
+DEBUG(D_tls) debug_printf("loading CRL file = %s\n", crl);
+if ((cert_count = gnutls_certificate_set_x509_crl_file(state->lib_state.x509_cred,
+ CS crl, GNUTLS_X509_FMT_PEM)) < 0)
+ return tls_error_gnu(state, US"gnutls_certificate_set_x509_crl_file",
+ cert_count, errstr);
+
+DEBUG(D_tls) debug_printf("Processed %d CRLs\n", cert_count);
return OK;
}
+static int
+creds_load_pristring(exim_gnutls_state_st * state, const uschar * p,
+ const char ** errpos)
+{
+if (!p)
+ {
+ p = exim_default_gnutls_priority;
+ DEBUG(D_tls)
+ debug_printf("GnuTLS using default session cipher/priority \"%s\"\n", p);
+ }
+return gnutls_priority_init( (gnutls_priority_t *) &state->lib_state.pri_cache,
+ CCS p, errpos);
+}
+static unsigned
+tls_server_creds_init(void)
+{
+uschar * dummy_errstr;
+unsigned lifetime = 0;
-/*************************************************
-* Remove from a priority list *
-*************************************************/
+state_server.lib_state = null_tls_preload;
+if (gnutls_certificate_allocate_credentials(
+ (gnutls_certificate_credentials_t *) &state_server.lib_state.x509_cred))
+ {
+ state_server.lib_state.x509_cred = NULL;
+ return lifetime;
+ }
+creds_basic_init(state_server.lib_state.x509_cred, TRUE);
+
+#if defined(EXIM_HAVE_INOTIFY) || defined(EXIM_HAVE_KEVENT)
+/* If tls_certificate has any $ indicating expansions, it is not good.
+If tls_privatekey is set but has $, not good. Likewise for tls_ocsp_file.
+If all good (and tls_certificate set), load the cert(s). */
+
+if ( opt_set_and_noexpand(tls_certificate)
+# ifndef DISABLE_OCSP
+ && opt_unset_or_noexpand(tls_ocsp_file)
+# endif
+ && opt_unset_or_noexpand(tls_privatekey))
+ {
+ /* Set watches on the filenames. The implementation does de-duplication
+ so we can just blindly do them all.
+ */
+
+ if ( tls_set_watch(tls_certificate, TRUE)
+# ifndef DISABLE_OCSP
+ && tls_set_watch(tls_ocsp_file, TRUE)
+# endif
+ && tls_set_watch(tls_privatekey, TRUE))
+ {
+ DEBUG(D_tls) debug_printf("TLS: preloading server certs\n");
+ if (creds_load_server_certs(&state_server, tls_certificate,
+ tls_privatekey && *tls_privatekey ? tls_privatekey : tls_certificate,
+# ifdef DISABLE_OCSP
+ NULL,
+# else
+ tls_ocsp_file,
+# endif
+ &dummy_errstr) == 0)
+ state_server.lib_state.conn_certs = TRUE;
+ }
+ }
+else if ( !tls_certificate && !tls_privatekey
+# ifndef DISABLE_OCSP
+ && !tls_ocsp_file
+# endif
+ )
+ { /* Generate & preload a selfsigned cert. No files to watch. */
+ if ((tls_install_selfsign(&state_server, &dummy_errstr)) == OK)
+ {
+ state_server.lib_state.conn_certs = TRUE;
+ lifetime = f.running_in_test_harness ? 2 : 60 * 60; /* 1 hour */
+ }
+ }
+else
+ DEBUG(D_tls) debug_printf("TLS: not preloading server certs\n");
-/* Cautiously written so that it will remove duplicates if present.
+/* If tls_verify_certificates is non-empty and has no $, load CAs.
+If none was configured and we can't handle "system", treat as empty. */
-Arguments:
- list a zero-terminated list
- remove_list a zero-terminated list to be removed
+if ( opt_set_and_noexpand(tls_verify_certificates)
+#ifndef SUPPORT_SYSDEFAULT_CABUNDLE
+ && Ustrcmp(tls_verify_certificates, "system") != 0
+#endif
+ )
+ {
+ if (tls_set_watch(tls_verify_certificates, FALSE))
+ {
+ DEBUG(D_tls) debug_printf("TLS: preloading CA bundle for server\n");
+ if (creds_load_cabundle(&state_server, tls_verify_certificates,
+ NULL, &dummy_errstr) != OK)
+ return lifetime;
+ state_server.lib_state.cabundle = TRUE;
-Returns: nothing
-*/
+ /* If CAs loaded and tls_crl is non-empty and has no $, load it */
+
+ if (opt_set_and_noexpand(tls_crl))
+ {
+ if (tls_set_watch(tls_crl, FALSE))
+ {
+ DEBUG(D_tls) debug_printf("TLS: preloading CRL for server\n");
+ if (creds_load_crl(&state_server, tls_crl, &dummy_errstr) != OK)
+ return lifetime;
+ state_server.lib_state.crl = TRUE;
+ }
+ }
+ else
+ DEBUG(D_tls) debug_printf("TLS: not preloading CRL for server\n");
+ }
+ }
+else
+ DEBUG(D_tls) debug_printf("TLS: not preloading CA bundle for server\n");
+#endif /* EXIM_HAVE_INOTIFY */
+
+/* If tls_require_ciphers is non-empty and has no $, load the
+ciphers priority cache. If unset, load with the default.
+(server-only as the client one depends on non/DANE) */
+
+if (!tls_require_ciphers || opt_set_and_noexpand(tls_require_ciphers))
+ {
+ const char * dummy_errpos;
+ DEBUG(D_tls) debug_printf("TLS: preloading cipher list for server: %s\n",
+ tls_require_ciphers);
+ if ( creds_load_pristring(&state_server, tls_require_ciphers, &dummy_errpos)
+ == OK)
+ state_server.lib_state.pri_string = TRUE;
+ }
+else
+ DEBUG(D_tls) debug_printf("TLS: not preloading cipher list for server\n");
+return lifetime;
+}
+
+
+/* Preload whatever creds are static, onto a transport. The client can then
+just copy the pointer as it starts up. */
+
+/*XXX this is not called for a cmdline send. But one needing to use >1 conn would benefit,
+and there seems little downside. */
static void
-remove_priority(int *list, int *remove_list)
+tls_client_creds_init(transport_instance * t, BOOL watch)
{
-for (; *remove_list != 0; remove_list++)
+smtp_transport_options_block * ob = t->options_block;
+exim_gnutls_state_st tpt_dummy_state;
+host_item * dummy_host = (host_item *)1;
+uschar * dummy_errstr;
+
+if ( !exim_gnutls_base_init_done
+ && tls_g_init(&dummy_errstr) != OK)
+ return;
+
+ob->tls_preload = null_tls_preload;
+if (gnutls_certificate_allocate_credentials(
+ (struct gnutls_certificate_credentials_st **)&ob->tls_preload.x509_cred))
+ {
+ ob->tls_preload.x509_cred = NULL;
+ return;
+ }
+creds_basic_init(ob->tls_preload.x509_cred, FALSE);
+
+tpt_dummy_state.session = NULL;
+tpt_dummy_state.lib_state = ob->tls_preload;
+
+#if defined(EXIM_HAVE_INOTIFY) || defined(EXIM_HAVE_KEVENT)
+if ( opt_set_and_noexpand(ob->tls_certificate)
+ && opt_unset_or_noexpand(ob->tls_privatekey))
+ {
+ if ( !watch
+ || ( tls_set_watch(ob->tls_certificate, FALSE)
+ && tls_set_watch(ob->tls_privatekey, FALSE)
+ ) )
+ {
+ const uschar * pkey = ob->tls_privatekey;
+
+ DEBUG(D_tls)
+ debug_printf("TLS: preloading client certs for transport '%s'\n", t->name);
+
+ /* The state->lib_state.x509_cred is used for the certs load, and is the sole
+ structure element used. So we can set up a dummy. The hoat arg only
+ selects a retcode in case of fail, so any value */
+
+ if (creds_load_client_certs(&tpt_dummy_state, dummy_host,
+ ob->tls_certificate, pkey ? pkey : ob->tls_certificate,
+ &dummy_errstr) == OK)
+ ob->tls_preload.conn_certs = TRUE;
+ }
+ }
+else
+ DEBUG(D_tls)
+ debug_printf("TLS: not preloading client certs, for transport '%s'\n", t->name);
+
+/* If tls_verify_certificates is non-empty and has no $, load CAs.
+If none was configured and we can't handle "system", treat as empty. */
+
+if ( opt_set_and_noexpand(ob->tls_verify_certificates)
+#ifndef SUPPORT_SYSDEFAULT_CABUNDLE
+ && Ustrcmp(ob->tls_verify_certificates, "system") != 0
+#endif
+ )
{
- int *p = list;
- while (*p != 0)
+ if (!watch || tls_set_watch(ob->tls_verify_certificates, FALSE))
{
- if (*p == *remove_list)
+ DEBUG(D_tls)
+ debug_printf("TLS: preloading CA bundle for transport '%s'\n", t->name);
+ if (creds_load_cabundle(&tpt_dummy_state, ob->tls_verify_certificates,
+ dummy_host, &dummy_errstr) != OK)
+ return;
+ ob->tls_preload.cabundle = TRUE;
+
+ if (opt_set_and_noexpand(ob->tls_crl))
{
- int *pp = p;
- do { pp[0] = pp[1]; pp++; } while (*pp != 0);
+ if (!watch || tls_set_watch(ob->tls_crl, FALSE))
+ {
+ DEBUG(D_tls) debug_printf("TLS: preloading CRL for transport '%s'\n", t->name);
+ if (creds_load_crl(&tpt_dummy_state, ob->tls_crl, &dummy_errstr) != OK)
+ return;
+ ob->tls_preload.crl = TRUE;
+ }
}
- else p++;
+ else
+ DEBUG(D_tls) debug_printf("TLS: not preloading CRL, for transport '%s'\n", t->name);
}
}
+else
+ DEBUG(D_tls)
+ debug_printf("TLS: not preloading CA bundle, for transport '%s'\n", t->name);
+
+/* We do not preload tls_require_ciphers to to the transport as it implicitly
+depends on DANE or plain usage. */
+
+#endif
+}
+
+
+#if defined(EXIM_HAVE_INOTIFY) || defined(EXIM_HAVE_KEVENT)
+/* Invalidate the creds cached, by dropping the current ones.
+Call when we notice one of the source files has changed. */
+
+static void
+tls_server_creds_invalidate(void)
+{
+if (state_server.lib_state.pri_cache)
+ gnutls_priority_deinit(state_server.lib_state.pri_cache);
+state_server.lib_state.pri_cache = NULL;
+
+if (state_server.lib_state.x509_cred)
+ gnutls_certificate_free_credentials(state_server.lib_state.x509_cred);
+state_server.lib_state = null_tls_preload;
}
+static void
+tls_client_creds_invalidate(transport_instance * t)
+{
+smtp_transport_options_block * ob = t->options_block;
+if (ob->tls_preload.x509_cred)
+ gnutls_certificate_free_credentials(ob->tls_preload.x509_cred);
+ob->tls_preload = null_tls_preload;
+}
+#endif
+
/*************************************************
-* Add to a priority list *
+* Variables re-expanded post-SNI *
*************************************************/
-/* Cautiously written to check the list size
+/* Called from both server and client code, via tls_init(), and also from
+the SNI callback after receiving an SNI, if tls_certificate includes "tls_sni".
+
+We can tell the two apart by state->received_sni being non-NULL in callback.
+
+The callback should not call us unless state->trigger_sni_changes is true,
+which we are responsible for setting on the first pass through.
Arguments:
- list a zero-terminated list
- list_max maximum offset in the list
- add_list a zero-terminated list to be added
+ state exim_gnutls_state_st *
+ errstr error string pointer
-Returns: TRUE if OK; FALSE if list overflows
+Returns: OK/DEFER/FAIL
*/
-static BOOL
-add_priority(int *list, int list_max, int *add_list)
+static int
+tls_expand_session_files(exim_gnutls_state_st * state, uschar ** errstr)
{
-int next = 0;
-while (list[next] != 0) next++;
-while (*add_list != 0)
+int rc;
+const host_item *host = state->host; /* macro should be reconsidered? */
+const uschar *saved_tls_certificate = NULL;
+const uschar *saved_tls_privatekey = NULL;
+const uschar *saved_tls_verify_certificates = NULL;
+const uschar *saved_tls_crl = NULL;
+int cert_count;
+
+/* We check for tls_sni *before* expansion. */
+if (!host) /* server */
+ if (!state->received_sni)
+ {
+ if ( state->tls_certificate
+ && ( Ustrstr(state->tls_certificate, US"tls_sni")
+ || Ustrstr(state->tls_certificate, US"tls_in_sni")
+ || Ustrstr(state->tls_certificate, US"tls_out_sni")
+ ) )
+ {
+ DEBUG(D_tls) debug_printf("We will re-expand TLS session files if we receive SNI\n");
+ state->trigger_sni_changes = TRUE;
+ }
+ }
+ else /* SNI callback case */
+ {
+ /* useful for debugging */
+ saved_tls_certificate = state->exp_tls_certificate;
+ saved_tls_privatekey = state->exp_tls_privatekey;
+ saved_tls_verify_certificates = state->exp_tls_verify_certificates;
+ saved_tls_crl = state->exp_tls_crl;
+ }
+
+if (!state->lib_state.x509_cred)
{
- if (next >= list_max) return FALSE;
- list[next++] = *add_list++;
+ if ((rc = gnutls_certificate_allocate_credentials(
+ (gnutls_certificate_credentials_t *) &state->lib_state.x509_cred)))
+ return tls_error_gnu(state, US"gnutls_certificate_allocate_credentials",
+ rc, errstr);
+ creds_basic_init(state->lib_state.x509_cred, !host);
}
-list[next] = 0;
-return TRUE;
-}
+/* remember: Expand_check_tlsvar() is expand_check() but fiddling with
+state members, assuming consistent naming; and expand_check() returns
+false if expansion failed, unless expansion was forced to fail. */
-/*************************************************
-* Adjust a priority list *
-*************************************************/
+/* check if we at least have a certificate, before doing expensive
+D-H generation. */
+
+if (!state->lib_state.conn_certs)
+ {
+ if (!Expand_check_tlsvar(tls_certificate, errstr))
+ return DEFER;
-/* This function is called to adjust the lists of cipher algorithms, MAC
-algorithms, key-exchange methods, and protocols.
+ /* certificate is mandatory in server, optional in client */
-Arguments:
- plist the appropriate priority list
- psize the length of the list
- s the configuation string
- index the index of recognized strings
- isize the length of the index
+ if ( !state->exp_tls_certificate
+ || !*state->exp_tls_certificate
+ )
+ if (!host)
+ return tls_install_selfsign(state, errstr);
+ else
+ DEBUG(D_tls) debug_printf("TLS: no client certificate specified; okay\n");
+ if (state->tls_privatekey && !Expand_check_tlsvar(tls_privatekey, errstr))
+ return DEFER;
- which text for an error message
+ /* tls_privatekey is optional, defaulting to same file as certificate */
-Returns: FALSE if the table overflows, else TRUE
-*/
+ if (!state->tls_privatekey || !*state->tls_privatekey)
+ {
+ state->tls_privatekey = state->tls_certificate;
+ state->exp_tls_privatekey = state->exp_tls_certificate;
+ }
-static BOOL
-set_priority(int *plist, int psize, uschar *s, pri_item *index, int isize,
- uschar *which)
-{
-int sep = 0;
-BOOL first = TRUE;
-uschar *t;
+ if (state->exp_tls_certificate && *state->exp_tls_certificate)
+ {
+ BOOL load = TRUE;
+ DEBUG(D_tls) debug_printf("certificate file = %s\nkey file = %s\n",
+ state->exp_tls_certificate, state->exp_tls_privatekey);
+
+ if (state->received_sni)
+ if ( Ustrcmp(state->exp_tls_certificate, saved_tls_certificate) == 0
+ && Ustrcmp(state->exp_tls_privatekey, saved_tls_privatekey) == 0
+ )
+ {
+ DEBUG(D_tls) debug_printf("TLS SNI: cert and key unchanged\n");
+ load = FALSE; /* avoid re-loading the same certs */
+ }
+ else /* unload the pre-SNI certs before loading new ones */
+ {
+ DEBUG(D_tls) debug_printf("TLS SNI: have a changed cert/key pair\n");
+ gnutls_certificate_free_keys(state->lib_state.x509_cred);
+ }
+
+ if ( load
+ && (rc = host
+ ? creds_load_client_certs(state, host, state->exp_tls_certificate,
+ state->exp_tls_privatekey, errstr)
+ : creds_load_server_certs(state, state->exp_tls_certificate,
+ state->exp_tls_privatekey,
+#ifdef DISABLE_OCSP
+ NULL,
+#else
+ tls_ocsp_file,
+#endif
+ errstr)
+ ) ) return rc;
+ }
+ }
+else
+ {
+ DEBUG(D_tls)
+ debug_printf("%s certs were preloaded\n", host ? "client" : "server");
+
+ if (!state->tls_privatekey) state->tls_privatekey = state->tls_certificate;
+ state->exp_tls_certificate = US state->tls_certificate;
+ state->exp_tls_privatekey = US state->tls_privatekey;
-while ((t = string_nextinlist(&s, &sep, big_buffer, big_buffer_size)) != NULL)
+#ifdef SUPPORT_GNUTLS_EXT_RAW_PARSE
+ if (state->lib_state.ocsp_hook)
+ gnutls_handshake_set_hook_function(state->session,
+ GNUTLS_HANDSHAKE_ANY, GNUTLS_HOOK_POST, tls_server_hook_cb);
+#endif
+ }
+
+
+/* Set the trusted CAs file if one is provided, and then add the CRL if one is
+provided. Experiment shows that, if the certificate file is empty, an unhelpful
+error message is provided. However, if we just refrain from setting anything up
+in that case, certificate verification fails, which seems to be the correct
+behaviour.
+If none was configured and we can't handle "system", treat as empty. */
+
+if (!state->lib_state.cabundle)
{
- int i;
- BOOL exclude = t[0] == '!';
- if (first && !exclude) plist[0] = 0;
- first = FALSE;
- for (i = 0; i < isize; i++)
+ if (state->tls_verify_certificates && *state->tls_verify_certificates)
{
- uschar *ss = strstric(t, index[i].name, FALSE);
- if (ss != NULL)
+ if (!Expand_check_tlsvar(tls_verify_certificates, errstr))
+ return DEFER;
+#ifndef SUPPORT_SYSDEFAULT_CABUNDLE
+ if (Ustrcmp(state->exp_tls_verify_certificates, "system") == 0)
+ state->exp_tls_verify_certificates = NULL;
+#endif
+ if (state->tls_crl && *state->tls_crl)
+ if (!Expand_check_tlsvar(tls_crl, errstr))
+ return DEFER;
+
+ if (!(state->exp_tls_verify_certificates &&
+ *state->exp_tls_verify_certificates))
{
- uschar *endss = ss + Ustrlen(index[i].name);
- if ((ss == t || !isalnum(ss[-1])) && !isalnum(*endss))
- {
- if (exclude)
- remove_priority(plist, index[i].values);
- else
- {
- if (!add_priority(plist, psize, index[i].values))
- {
- log_write(0, LOG_MAIN|LOG_PANIC, "GnuTLS init failed: %s "
- "priority table overflow", which);
- return FALSE;
- }
- }
- }
+ DEBUG(D_tls)
+ debug_printf("TLS: tls_verify_certificates expanded empty, ignoring\n");
+ /* With no tls_verify_certificates, we ignore tls_crl too */
+ return OK;
}
}
+ else
+ {
+ DEBUG(D_tls)
+ debug_printf("TLS: tls_verify_certificates not set or empty, ignoring\n");
+ return OK;
+ }
+ rc = creds_load_cabundle(state, state->exp_tls_verify_certificates, host, errstr);
+ if (rc != OK) return rc;
+ }
+else
+ {
+ DEBUG(D_tls)
+ debug_printf("%s CA bundle was preloaded\n", host ? "client" : "server");
+ state->exp_tls_verify_certificates = US state->tls_verify_certificates;
+
+#ifdef SUPPORT_CA_DIR
+/* Mimic the behaviour with OpenSSL of not advertising a usable-cert list
+when using the directory-of-certs config model. */
+ if (state->lib_state.ca_rdn_emulate)
+ gnutls_certificate_send_x509_rdn_sequence(state->session, 1);
+#endif
}
-DEBUG(D_tls)
+
+if (!state->lib_state.crl)
+ {
+ if ( state->tls_crl && *state->tls_crl
+ && state->exp_tls_crl && *state->exp_tls_crl)
+ return creds_load_crl(state, state->exp_tls_crl, errstr);
+ }
+else
{
- int *ptr = plist;
- debug_printf("adjusted %s priorities:", which);
- while (*ptr != 0) debug_printf(" %d", *ptr++);
- debug_printf("\n");
+ DEBUG(D_tls)
+ debug_printf("%s CRL was preloaded\n", host ? "client" : "server");
+ state->exp_tls_crl = US state->tls_crl;
}
-return TRUE;
+return OK;
}
/*************************************************
-* Initialize a single GNUTLS session *
+* Set X.509 state variables *
*************************************************/
-/* Set the algorithm, the db backend, whether to request certificates etc.
+/* In GnuTLS, the registered cert/key are not replaced by a later
+set of a cert/key, so for SNI support we need a whole new x509_cred
+structure. Which means various other non-re-expanded pieces of state
+need to be re-set in the new struct, so the setting logic is pulled
+out to this.
+
+Arguments:
+ state exim_gnutls_state_st *
+ errstr error string pointer
+
+Returns: OK/DEFER/FAIL
+*/
+
+static int
+tls_set_remaining_x509(exim_gnutls_state_st *state, uschar ** errstr)
+{
+int rc;
+const host_item *host = state->host; /* macro should be reconsidered? */
+
+/* Create D-H parameters, or read them from the cache file. This function does
+its own SMTP error messaging. This only happens for the server, TLS D-H ignores
+client-side params. */
+
+if (!state->host)
+ {
+ if (!dh_server_params)
+ if ((rc = init_server_dh(errstr)) != OK) return rc;
+
+ /* Unnecessary & discouraged with 3.6.0 or later, according to docs. But without it,
+ no DHE- ciphers are advertised. */
+ gnutls_certificate_set_dh_params(state->lib_state.x509_cred, dh_server_params);
+ }
+
+/* Link the credentials to the session. */
+
+if ((rc = gnutls_credentials_set(state->session,
+ GNUTLS_CRD_CERTIFICATE, state->lib_state.x509_cred)))
+ return tls_error_gnu(state, US"gnutls_credentials_set", rc, errstr);
-TLS in Exim was first implemented using OpenSSL. This has a function to which
-you pass a list of cipher suites that are permitted/not permitted. GnuTLS works
-differently. It operates using priority lists for the different components of
-cipher suites.
+return OK;
+}
+
+/*************************************************
+* Initialize for GnuTLS *
+*************************************************/
-For compatibility of configuration, we scan a list of cipher suites and set
-priorities therefrom. However, at the moment, we pay attention only to the bulk
-cipher.
+
+/* Called from both server and client code. In the case of a server, errors
+before actual TLS negotiation return DEFER.
Arguments:
- side one of GNUTLS_SERVER, GNUTLS_CLIENT
- expciphers expanded ciphers list or NULL
- expmac expanded MAC list or NULL
- expkx expanded key-exchange list or NULL
- expproto expanded protocol list or NULL
+ host connected host, if client; NULL if server
+ ob tranport options block, if client; NULL if server
+ require_ciphers tls_require_ciphers setting
+ caller_state returned state-info structure
+ errstr error string pointer
-Returns: a gnutls_session, or NULL if there is a problem
+Returns: OK/DEFER/FAIL
*/
-static gnutls_session
-tls_session_init(int side, uschar *expciphers, uschar *expmac, uschar *expkx,
- uschar *expproto)
+static int
+tls_init(
+ const host_item *host,
+ smtp_transport_options_block * ob,
+ const uschar * require_ciphers,
+ exim_gnutls_state_st **caller_state,
+ tls_support * tlsp,
+ uschar ** errstr)
{
-gnutls_session session;
+exim_gnutls_state_st * state;
+int rc;
+size_t sz;
+
+if ( !exim_gnutls_base_init_done
+ && (rc = tls_g_init(errstr)) != OK)
+ return rc;
+
+if (host)
+ {
+ /* For client-side sessions we allocate a context. This lets us run
+ several in parallel. */
+
+ int old_pool = store_pool;
+ store_pool = POOL_PERM;
+ state = store_get(sizeof(exim_gnutls_state_st), GET_UNTAINTED);
+ store_pool = old_pool;
+
+ memcpy(state, &exim_gnutls_state_init, sizeof(exim_gnutls_state_init));
+ state->lib_state = ob->tls_preload;
+ state->tlsp = tlsp;
+ DEBUG(D_tls) debug_printf("initialising GnuTLS client session\n");
+ rc = gnutls_init(&state->session, GNUTLS_CLIENT);
+
+ state->tls_certificate = ob->tls_certificate;
+ state->tls_privatekey = ob->tls_privatekey;
+ state->tls_sni = ob->tls_sni;
+ state->tls_verify_certificates = ob->tls_verify_certificates;
+ state->tls_crl = ob->tls_crl;
+ }
+else
+ {
+ /* Server operations always use the one state_server context. It is not
+ shared because we have forked a fresh process for every receive. However it
+ can get re-used for successive TLS sessions on a single TCP connection. */
+
+ state = &state_server;
+ state->tlsp = tlsp;
+ DEBUG(D_tls) debug_printf("initialising GnuTLS server session\n");
+ rc = gnutls_init(&state->session, GNUTLS_SERVER);
+
+ state->tls_certificate = tls_certificate;
+ state->tls_privatekey = tls_privatekey;
+ state->tls_sni = NULL;
+ state->tls_verify_certificates = tls_verify_certificates;
+ state->tls_crl = tls_crl;
+ }
+if (rc)
+ return tls_error_gnu(state, US"gnutls_init", rc, errstr);
-gnutls_init(&session, side);
+state->tls_require_ciphers = require_ciphers;
+state->host = host;
-/* Initialize the lists of permitted protocols, key-exchange methods, ciphers,
-and MACs. */
+/* This handles the variables that might get re-expanded after TLS SNI;
+tls_certificate, tls_privatekey, tls_verify_certificates, tls_crl */
-memcpy(cipher_priority, default_cipher_priority, sizeof(cipher_priority));
-memcpy(mac_priority, default_mac_priority, sizeof(mac_priority));
-memcpy(kx_priority, default_kx_priority, sizeof(kx_priority));
-memcpy(proto_priority, default_proto_priority, sizeof(proto_priority));
+DEBUG(D_tls)
+ debug_printf("Expanding various TLS configuration options for session credentials\n");
+if ((rc = tls_expand_session_files(state, errstr)) != OK) return rc;
+
+/* These are all other parts of the x509_cred handling, since SNI in GnuTLS
+requires a new structure afterwards. */
-/* The names OpenSSL uses in tls_require_ciphers are of the form DES-CBC3-SHA,
-using hyphen separators. GnuTLS uses underscore separators. So that I can use
-either form for tls_require_ciphers in my tests, and also for general
-convenience, we turn hyphens into underscores before scanning the list. */
+if ((rc = tls_set_remaining_x509(state, errstr)) != OK) return rc;
-if (expciphers != NULL)
+/* set SNI in client, only */
+if (host)
{
- uschar *s = expciphers;
- while (*s != 0) { if (*s == '-') *s = '_'; s++; }
+ if (!expand_check(state->tls_sni, US"tls_out_sni", &state->tlsp->sni, errstr))
+ return DEFER;
+ if (state->tlsp->sni && *state->tlsp->sni)
+ {
+ DEBUG(D_tls)
+ debug_printf("Setting TLS client SNI to \"%s\"\n", state->tlsp->sni);
+ sz = Ustrlen(state->tlsp->sni);
+ if ((rc = gnutls_server_name_set(state->session,
+ GNUTLS_NAME_DNS, state->tlsp->sni, sz)))
+ return tls_error_gnu(state, US"gnutls_server_name_set", rc, errstr);
+ }
}
+else if (state->tls_sni)
+ DEBUG(D_tls) debug_printf("*** PROBABLY A BUG *** " \
+ "have an SNI set for a server [%s]\n", state->tls_sni);
-if ((expciphers != NULL &&
- !set_priority(cipher_priority, sizeof(cipher_priority)/sizeof(int),
- expciphers, cipher_index, sizeof(cipher_index)/sizeof(pri_item),
- US"cipher")) ||
- (expmac != NULL &&
- !set_priority(mac_priority, sizeof(mac_priority)/sizeof(int),
- expmac, mac_index, sizeof(mac_index)/sizeof(pri_item),
- US"MAC")) ||
- (expkx != NULL &&
- !set_priority(kx_priority, sizeof(kx_priority)/sizeof(int),
- expkx, kx_index, sizeof(kx_index)/sizeof(pri_item),
- US"key-exchange")) ||
- (expproto != NULL &&
- !set_priority(proto_priority, sizeof(proto_priority)/sizeof(int),
- expproto, proto_index, sizeof(proto_index)/sizeof(pri_item),
- US"protocol")))
+if (!state->lib_state.pri_string)
{
- gnutls_deinit(session);
- return NULL;
- }
+ const uschar * p = NULL;
+ const char * errpos;
-/* Define the various priorities */
+ /* This is the priority string support,
+ http://www.gnutls.org/manual/html_node/Priority-Strings.html
+ and replaces gnutls_require_kx, gnutls_require_mac & gnutls_require_protocols.
+ This was backwards incompatible, but means Exim no longer needs to track
+ all algorithms and provide string forms for them. */
+
+ if (state->tls_require_ciphers && *state->tls_require_ciphers)
+ {
+ if (!Expand_check_tlsvar(tls_require_ciphers, errstr))
+ return DEFER;
+ if (state->exp_tls_require_ciphers && *state->exp_tls_require_ciphers)
+ {
+ p = state->exp_tls_require_ciphers;
+ DEBUG(D_tls) debug_printf("GnuTLS session cipher/priority \"%s\"\n", p);
+ }
+ }
-gnutls_cipher_set_priority(session, cipher_priority);
-gnutls_compression_set_priority(session, comp_priority);
-gnutls_kx_set_priority(session, kx_priority);
-gnutls_protocol_set_priority(session, proto_priority);
-gnutls_mac_set_priority(session, mac_priority);
+ if ((rc = creds_load_pristring(state, p, &errpos)))
+ return tls_error_gnu(state, string_sprintf(
+ "gnutls_priority_init(%s) failed at offset %ld, \"%.6s..\"",
+ p, (long)(errpos - CS p), errpos),
+ rc, errstr);
+ }
+else
+ {
+ DEBUG(D_tls) debug_printf("cipher list preloaded\n");
+ state->exp_tls_require_ciphers = US state->tls_require_ciphers;
+ }
-gnutls_cred_set(session, GNUTLS_CRD_CERTIFICATE, x509_cred);
-gnutls_dh_set_prime_bits(session, DH_BITS);
+if ((rc = gnutls_priority_set(state->session, state->lib_state.pri_cache)))
+ return tls_error_gnu(state, US"gnutls_priority_set", rc, errstr);
-/* Request or demand a certificate of the peer, as configured. This will
-happen only in a server. */
+/* This also sets the server ticket expiration time to the same, and
+the STEK rotation time to 3x. */
-if (verify_requirement != VERIFY_NONE)
- gnutls_certificate_server_set_request(session,
- (verify_requirement == VERIFY_OPTIONAL)?
- GNUTLS_CERT_REQUEST : GNUTLS_CERT_REQUIRE);
+gnutls_db_set_cache_expiration(state->session, ssl_session_timeout);
-gnutls_db_set_cache_expiration(session, ssl_session_timeout);
+/* Reduce security in favour of increased compatibility, if the admin
+decides to make that trade-off. */
+if (gnutls_compat_mode)
+ {
+#if LIBGNUTLS_VERSION_NUMBER >= 0x020104
+ DEBUG(D_tls) debug_printf("lowering GnuTLS security, compatibility mode\n");
+ gnutls_session_enable_compatibility_mode(state->session);
+#else
+ DEBUG(D_tls) debug_printf("Unable to set gnutls_compat_mode - GnuTLS version too old\n");
+#endif
+ }
-DEBUG(D_tls) debug_printf("initialized GnuTLS session\n");
-return session;
+*caller_state = state;
+return OK;
}
/*************************************************
-* Get name of cipher in use *
+* Extract peer information *
*************************************************/
-/* The answer is left in a static buffer, and tls_cipher is set to point
-to it.
+static const uschar *
+cipher_stdname_kcm(gnutls_kx_algorithm_t kx, gnutls_cipher_algorithm_t cipher,
+ gnutls_mac_algorithm_t mac)
+{
+uschar cs_id[2];
+gnutls_kx_algorithm_t kx_i;
+gnutls_cipher_algorithm_t cipher_i;
+gnutls_mac_algorithm_t mac_i;
+
+for (size_t i = 0;
+ gnutls_cipher_suite_info(i, cs_id, &kx_i, &cipher_i, &mac_i, NULL);
+ i++)
+ if (kx_i == kx && cipher_i == cipher && mac_i == mac)
+ return cipher_stdname(cs_id[0], cs_id[1]);
+return NULL;
+}
+
+
+
+/* Called from both server and client code.
+Only this is allowed to set state->peerdn and state->have_set_peerdn
+and we use that to detect double-calls.
+
+NOTE: the state blocks last while the TLS connection is up, which is fine
+for logging in the server side, but for the client side, we log after teardown
+in src/deliver.c. While the session is up, we can twist about states and
+repoint tls_* globals, but those variables used for logging or other variable
+expansion that happens _after_ delivery need to have a longer life-time.
+
+So for those, we get the data from POOL_PERM; the re-invoke guard keeps us from
+doing this more than once per generation of a state context. We set them in
+the state context, and repoint tls_* to them. After the state goes away, the
+tls_* copies of the pointers remain valid and client delivery logging is happy.
+
+tls_certificate_verified is a BOOL, so the tls_peerdn and tls_cipher issues
+don't apply.
+
+Arguments:
+ state exim_gnutls_state_st *
+ errstr pointer to error string
-Argument: pointer to a GnuTLS session
-Returns: nothing
+Returns: OK/DEFER/FAIL
*/
-static void
-construct_cipher_name(gnutls_session session)
+static int
+peer_status(exim_gnutls_state_st * state, uschar ** errstr)
{
-static uschar cipherbuf[256];
-uschar *ver;
-int bits, c, kx, mac;
+gnutls_session_t session = state->session;
+const gnutls_datum_t * cert_list;
+int old_pool, rc;
+unsigned int cert_list_size = 0;
+gnutls_protocol_t protocol;
+gnutls_cipher_algorithm_t cipher;
+gnutls_kx_algorithm_t kx;
+gnutls_mac_algorithm_t mac;
+gnutls_certificate_type_t ct;
+gnutls_x509_crt_t crt;
+uschar * dn_buf;
+size_t sz;
+
+if (state->have_set_peerdn)
+ return OK;
+state->have_set_peerdn = TRUE;
+
+state->peerdn = NULL;
+
+/* tls_cipher */
+cipher = gnutls_cipher_get(session);
+protocol = gnutls_protocol_get_version(session);
+mac = gnutls_mac_get(session);
+kx =
+#ifdef GNUTLS_TLS1_3
+ protocol >= GNUTLS_TLS1_3 ? 0 :
+#endif
+ gnutls_kx_get(session);
-ver = string_copy(
- US gnutls_protocol_get_name(gnutls_protocol_get_version(session)));
-if (Ustrncmp(ver, "TLS ", 4) == 0) ver[3] = '-'; /* Don't want space */
+old_pool = store_pool;
+ {
+ tls_support * tlsp = state->tlsp;
+ store_pool = POOL_PERM;
-c = gnutls_cipher_get(session);
-bits = gnutls_cipher_get_key_size(c);
+#ifdef SUPPORT_GNUTLS_SESS_DESC
+ {
+ gstring * g = NULL;
+ uschar * s = US gnutls_session_get_desc(session), c;
-mac = gnutls_mac_get(session);
-kx = gnutls_kx_get(session);
+ /* Nikos M suggests we use this by preference. It returns like:
+ (TLS1.3)-(ECDHE-SECP256R1)-(RSA-PSS-RSAE-SHA256)-(AES-256-GCM)
-string_format(cipherbuf, sizeof(cipherbuf), "%s:%s:%u", ver,
- gnutls_cipher_suite_get_name(kx, c, mac), bits);
-tls_cipher = cipherbuf;
+ For partial back-compat, put a colon after the TLS version, replace the
+ )-( grouping with __, replace in-group - with _ and append the :keysize. */
-DEBUG(D_tls) debug_printf("cipher: %s\n", cipherbuf);
-}
+ /* debug_printf("peer_status: gnutls_session_get_desc %s\n", s); */
+ for (s++; (c = *s) && c != ')'; s++) g = string_catn(g, s, 1);
+ tlsp->ver = string_copyn(g->s, g->ptr);
+ for (uschar * p = US tlsp->ver; *p; p++)
+ if (*p == '-') { *p = '\0'; break; } /* TLS1.0-PKIX -> TLS1.0 */
-/*************************************************
-* Start a TLS session in a server *
-*************************************************/
+ g = string_catn(g, US":", 1);
+ if (*s) s++; /* now on _ between groups */
+ while ((c = *s))
+ {
+ for (*++s && ++s; (c = *s) && c != ')'; s++)
+ g = string_catn(g, c == '-' ? US"_" : s, 1);
+ /* now on ) closing group */
+ if ((c = *s) && *++s == '-') g = string_catn(g, US"__", 2);
+ /* now on _ between groups */
+ }
+ g = string_catn(g, US":", 1);
+ g = string_cat(g, string_sprintf("%d", (int) gnutls_cipher_get_key_size(cipher) * 8));
+ state->ciphersuite = string_from_gstring(g);
+ }
+#else
+ state->ciphersuite = string_sprintf("%s:%s:%d",
+ gnutls_protocol_get_name(protocol),
+ gnutls_cipher_suite_get_name(kx, cipher, mac),
+ (int) gnutls_cipher_get_key_size(cipher) * 8);
-/* This is called when Exim is running as a server, after having received
-the STARTTLS command. It must respond to that command, and then negotiate
-a TLS session.
+ /* I don't see a way that spaces could occur, in the current GnuTLS
+ code base, but it was a concern in the old code and perhaps older GnuTLS
+ releases did return "TLS 1.0"; play it safe, just in case. */
-Arguments:
- require_ciphers list of allowed ciphers or NULL
- require_mac list of allowed MACs or NULL
- require_kx list of allowed key_exchange methods or NULL
- require_proto list of allowed protocols or NULL
+ for (uschar * p = state->ciphersuite; *p; p++) if (isspace(*p)) *p = '-';
+ tlsp->ver = string_copyn(state->ciphersuite,
+ Ustrchr(state->ciphersuite, ':') - state->ciphersuite);
+#endif
-Returns: OK on success
- DEFER for errors before the start of the negotiation
- FAIL for errors during the negotation; the server can't
- continue running.
-*/
+/* debug_printf("peer_status: ciphersuite %s\n", state->ciphersuite); */
-int
-tls_server_start(uschar *require_ciphers, uschar *require_mac,
- uschar *require_kx, uschar *require_proto)
-{
+ tlsp->cipher = state->ciphersuite;
+ tlsp->bits = gnutls_cipher_get_key_size(cipher) * 8;
+
+ tlsp->cipher_stdname = cipher_stdname_kcm(kx, cipher, mac);
+ }
+store_pool = old_pool;
+
+/* tls_peerdn */
+cert_list = gnutls_certificate_get_peers(session, &cert_list_size);
+
+if (!cert_list || cert_list_size == 0)
+ {
+ DEBUG(D_tls) debug_printf("TLS: no certificate from peer (%p & %d)\n",
+ cert_list, cert_list_size);
+ if (state->verify_requirement >= VERIFY_REQUIRED)
+ return tls_error(US"certificate verification failed",
+ US"no certificate received from peer", state->host, errstr);
+ return OK;
+ }
+
+if ((ct = gnutls_certificate_type_get(session)) != GNUTLS_CRT_X509)
+ {
+ const uschar * ctn = US gnutls_certificate_type_get_name(ct);
+ DEBUG(D_tls)
+ debug_printf("TLS: peer cert not X.509 but instead \"%s\"\n", ctn);
+ if (state->verify_requirement >= VERIFY_REQUIRED)
+ return tls_error(US"certificate verification not possible, unhandled type",
+ ctn, state->host, errstr);
+ return OK;
+ }
+
+#define exim_gnutls_peer_err(Label) \
+ do { \
+ if (rc != GNUTLS_E_SUCCESS) \
+ { \
+ DEBUG(D_tls) debug_printf("TLS: peer cert problem: %s: %s\n", \
+ (Label), gnutls_strerror(rc)); \
+ if (state->verify_requirement >= VERIFY_REQUIRED) \
+ return tls_error_gnu(state, (Label), rc, errstr); \
+ return OK; \
+ } \
+ } while (0)
+
+rc = import_cert(&cert_list[0], &crt);
+exim_gnutls_peer_err(US"cert 0");
+
+state->tlsp->peercert = state->peercert = crt;
+
+sz = 0;
+rc = gnutls_x509_crt_get_dn(crt, NULL, &sz);
+if (rc != GNUTLS_E_SHORT_MEMORY_BUFFER)
+ {
+ exim_gnutls_peer_err(US"getting size for cert DN failed");
+ return FAIL; /* should not happen */
+ }
+dn_buf = store_get_perm(sz, GET_TAINTED);
+rc = gnutls_x509_crt_get_dn(crt, CS dn_buf, &sz);
+exim_gnutls_peer_err(US"failed to extract certificate DN [gnutls_x509_crt_get_dn(cert 0)]");
+
+state->peerdn = dn_buf;
+
+return OK;
+#undef exim_gnutls_peer_err
+}
+
+
+
+
+/*************************************************
+* Verify peer certificate *
+*************************************************/
+
+/* Called from both server and client code.
+*Should* be using a callback registered with
+gnutls_certificate_set_verify_function() to fail the handshake if we dislike
+the peer information, but that's too new for some OSes.
+
+Arguments:
+ state exim_gnutls_state_st *
+ errstr where to put an error message
+
+Returns:
+ FALSE if the session should be rejected
+ TRUE if the cert is okay or we just don't care
+*/
+
+static BOOL
+verify_certificate(exim_gnutls_state_st * state, uschar ** errstr)
+{
int rc;
-uschar *error;
-uschar *expciphers = NULL;
-uschar *expmac = NULL;
-uschar *expkx = NULL;
-uschar *expproto = NULL;
+uint verify;
+
+DEBUG(D_tls) debug_printf("TLS: checking peer certificate\n");
+*errstr = NULL;
+rc = peer_status(state, errstr);
+
+if (state->verify_requirement == VERIFY_NONE)
+ return TRUE;
+
+if (rc != OK || !state->peerdn)
+ {
+ verify = GNUTLS_CERT_INVALID;
+ *errstr = US"certificate not supplied";
+ }
+else
+
+ {
+#ifdef SUPPORT_DANE
+ if (state->verify_requirement == VERIFY_DANE && state->host)
+ {
+ /* Using dane_verify_session_crt() would be easy, as it does it all for us
+ including talking to a DNS resolver. But we want to do that bit ourselves
+ as the testsuite intercepts and fakes its own DNS environment. */
+
+ dane_state_t s;
+ dane_query_t r;
+ uint lsize;
+ const gnutls_datum_t * certlist =
+ gnutls_certificate_get_peers(state->session, &lsize);
+ int usage = tls_out.tlsa_usage;
+
+# ifdef GNUTLS_BROKEN_DANE_VALIDATION
+ /* Split the TLSA records into two sets, TA and EE selectors. Run the
+ dane-verification separately so that we know which selector verified;
+ then we know whether to do name-verification (needed for TA but not EE). */
+
+ if (usage == ((1<<DANESSL_USAGE_DANE_TA) | (1<<DANESSL_USAGE_DANE_EE)))
+ { /* a mixed-usage bundle */
+ int i, j, nrec;
+ const char ** dd;
+ int * ddl;
+
+ for (nrec = 0; state->dane_data_len[nrec]; ) nrec++;
+ nrec++;
+
+ dd = store_get(nrec * sizeof(uschar *), GET_UNTAINTED);
+ ddl = store_get(nrec * sizeof(int), GET_UNTAINTED);
+ nrec--;
+
+ if ((rc = dane_state_init(&s, 0)))
+ goto tlsa_prob;
+
+ for (usage = DANESSL_USAGE_DANE_EE;
+ usage >= DANESSL_USAGE_DANE_TA; usage--)
+ { /* take records with this usage */
+ for (j = i = 0; i < nrec; i++)
+ if (state->dane_data[i][0] == usage)
+ {
+ dd[j] = state->dane_data[i];
+ ddl[j++] = state->dane_data_len[i];
+ }
+ if (j)
+ {
+ dd[j] = NULL;
+ ddl[j] = 0;
+
+ if ((rc = dane_raw_tlsa(s, &r, (char * const *)dd, ddl, 1, 0)))
+ goto tlsa_prob;
+
+ if ((rc = dane_verify_crt_raw(s, certlist, lsize,
+ gnutls_certificate_type_get(state->session),
+ r, 0,
+ usage == DANESSL_USAGE_DANE_EE
+ ? DANE_VFLAG_ONLY_CHECK_EE_USAGE : 0,
+ &verify)))
+ {
+ DEBUG(D_tls)
+ debug_printf("TLSA record problem: %s\n", dane_strerror(rc));
+ }
+ else if (verify == 0) /* verification passed */
+ {
+ usage = 1 << usage;
+ break;
+ }
+ }
+ }
+
+ if (rc) goto tlsa_prob;
+ }
+ else
+# endif
+ {
+ if ( (rc = dane_state_init(&s, 0))
+ || (rc = dane_raw_tlsa(s, &r, state->dane_data, state->dane_data_len,
+ 1, 0))
+ || (rc = dane_verify_crt_raw(s, certlist, lsize,
+ gnutls_certificate_type_get(state->session),
+ r, 0,
+# ifdef GNUTLS_BROKEN_DANE_VALIDATION
+ usage == (1 << DANESSL_USAGE_DANE_EE)
+ ? DANE_VFLAG_ONLY_CHECK_EE_USAGE : 0,
+# else
+ 0,
+# endif
+ &verify))
+ )
+ goto tlsa_prob;
+ }
+
+ if (verify != 0) /* verification failed */
+ {
+ gnutls_datum_t str;
+ (void) dane_verification_status_print(verify, &str, 0);
+ *errstr = US str.data; /* don't bother to free */
+ goto badcert;
+ }
+
+# ifdef GNUTLS_BROKEN_DANE_VALIDATION
+ /* If a TA-mode TLSA record was used for verification we must additionally
+ verify the cert name (but not the CA chain). For EE-mode, skip it. */
+
+ if (usage & (1 << DANESSL_USAGE_DANE_EE))
+# endif
+ {
+ state->peer_dane_verified = state->peer_cert_verified = TRUE;
+ goto goodcert;
+ }
+# ifdef GNUTLS_BROKEN_DANE_VALIDATION
+ /* Assume that the name on the A-record is the one that should be matching
+ the cert. An alternate view is that the domain part of the email address
+ is also permissible. */
+
+ if (gnutls_x509_crt_check_hostname(state->tlsp->peercert,
+ CS state->host->name))
+ {
+ state->peer_dane_verified = state->peer_cert_verified = TRUE;
+ goto goodcert;
+ }
+# endif
+ }
+#endif /*SUPPORT_DANE*/
+
+ rc = gnutls_certificate_verify_peers2(state->session, &verify);
+ }
+
+/* Handle the result of verification. INVALID is set if any others are. */
+
+if (rc < 0 || verify & (GNUTLS_CERT_INVALID|GNUTLS_CERT_REVOKED))
+ {
+ state->peer_cert_verified = FALSE;
+ if (!*errstr)
+ {
+#ifdef GNUTLS_CERT_VFY_STATUS_PRINT
+ DEBUG(D_tls)
+ {
+ gnutls_datum_t txt;
+
+ if (gnutls_certificate_verification_status_print(verify,
+ gnutls_certificate_type_get(state->session), &txt, 0)
+ == GNUTLS_E_SUCCESS)
+ {
+ debug_printf("%s\n", txt.data);
+ gnutls_free(txt.data);
+ }
+ }
+#endif
+ *errstr = verify & GNUTLS_CERT_REVOKED
+ ? US"certificate revoked" : US"certificate invalid";
+ }
+
+ DEBUG(D_tls)
+ debug_printf("TLS certificate verification failed (%s): peerdn=\"%s\"\n",
+ *errstr, state->peerdn ? state->peerdn : US"<unset>");
+
+ if (state->verify_requirement >= VERIFY_REQUIRED)
+ goto badcert;
+ DEBUG(D_tls)
+ debug_printf("TLS verify failure overridden (host in tls_try_verify_hosts)\n");
+ }
+
+else
+ {
+ /* Client side, check the server's certificate name versus the name on the
+ A-record for the connection we made. What to do for server side - what name
+ to use for client? We document that there is no such checking for server
+ side. */
+
+ if ( state->exp_tls_verify_cert_hostnames
+ && !gnutls_x509_crt_check_hostname(state->tlsp->peercert,
+ CS state->exp_tls_verify_cert_hostnames)
+ )
+ {
+ DEBUG(D_tls)
+ debug_printf("TLS certificate verification failed: cert name mismatch\n");
+ if (state->verify_requirement >= VERIFY_REQUIRED)
+ goto badcert;
+ return TRUE;
+ }
+
+ state->peer_cert_verified = TRUE;
+ DEBUG(D_tls) debug_printf("TLS certificate verified: peerdn=\"%s\"\n",
+ state->peerdn ? state->peerdn : US"<unset>");
+ }
+
+goodcert:
+ state->tlsp->peerdn = state->peerdn;
+ return TRUE;
+
+#ifdef SUPPORT_DANE
+tlsa_prob:
+ *errstr = string_sprintf("TLSA record problem: %s",
+ rc == DANE_E_REQUESTED_DATA_NOT_AVAILABLE ? "none usable" : dane_strerror(rc));
+#endif
+
+badcert:
+ gnutls_alert_send(state->session, GNUTLS_AL_FATAL, GNUTLS_A_BAD_CERTIFICATE);
+ return FALSE;
+}
+
+
+
+
+/* ------------------------------------------------------------------------ */
+/* Callbacks */
+
+/* Logging function which can be registered with
+ * gnutls_global_set_log_function()
+ * gnutls_global_set_log_level() 0..9
+ */
+#if EXIM_GNUTLS_LIBRARY_LOG_LEVEL >= 0
+static void
+exim_gnutls_logger_cb(int level, const char *message)
+{
+ size_t len = strlen(message);
+ if (len < 1)
+ {
+ DEBUG(D_tls) debug_printf("GnuTLS<%d> empty debug message\n", level);
+ return;
+ }
+ DEBUG(D_tls) debug_printf("GnuTLS<%d>: %s%s", level, message,
+ message[len-1] == '\n' ? "" : "\n");
+}
+#endif
+
+
+/* Called after client hello, should handle SNI work.
+This will always set tls_sni (state->received_sni) if available,
+and may trigger presenting different certificates,
+if state->trigger_sni_changes is TRUE.
+
+Should be registered with
+ gnutls_handshake_set_post_client_hello_function()
+
+"This callback must return 0 on success or a gnutls error code to terminate the
+handshake.".
+
+For inability to get SNI information, we return 0.
+We only return non-zero if re-setup failed.
+Only used for server-side TLS.
+*/
+
+static int
+exim_sni_handling_cb(gnutls_session_t session)
+{
+char sni_name[MAX_HOST_LEN];
+size_t data_len = MAX_HOST_LEN;
+exim_gnutls_state_st *state = &state_server;
+unsigned int sni_type;
+int rc, old_pool;
+uschar * dummy_errstr;
+
+rc = gnutls_server_name_get(session, sni_name, &data_len, &sni_type, 0);
+if (rc != GNUTLS_E_SUCCESS)
+ {
+ DEBUG(D_tls)
+ if (rc == GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE)
+ debug_printf("TLS: no SNI presented in handshake\n");
+ else
+ debug_printf("TLS failure: gnutls_server_name_get(): %s [%d]\n",
+ gnutls_strerror(rc), rc);
+ return 0;
+ }
+
+if (sni_type != GNUTLS_NAME_DNS)
+ {
+ DEBUG(D_tls) debug_printf("TLS: ignoring SNI of unhandled type %u\n", sni_type);
+ return 0;
+ }
+
+/* We now have a UTF-8 string in sni_name */
+old_pool = store_pool;
+store_pool = POOL_PERM;
+state->received_sni = string_copy_taint(US sni_name, GET_TAINTED);
+store_pool = old_pool;
+
+/* We set this one now so that variable expansions below will work */
+state->tlsp->sni = state->received_sni;
+
+DEBUG(D_tls) debug_printf("Received TLS SNI \"%s\"%s\n", sni_name,
+ state->trigger_sni_changes ? "" : " (unused for certificate selection)");
+
+if (!state->trigger_sni_changes)
+ return 0;
+
+if ((rc = tls_expand_session_files(state, &dummy_errstr)) != OK)
+ {
+ /* If the setup of certs/etc failed before handshake, TLS would not have
+ been offered. The best we can do now is abort. */
+ return GNUTLS_E_APPLICATION_ERROR_MIN;
+ }
+
+rc = tls_set_remaining_x509(state, &dummy_errstr);
+if (rc != OK) return GNUTLS_E_APPLICATION_ERROR_MIN;
+
+return 0;
+}
+
+
+
+#ifndef DISABLE_EVENT
+/*
+We use this callback to get observability and detail-level control
+for an exim TLS connection (either direction), raising a tls:cert event
+for each cert in the chain presented by the peer. Any event
+can deny verification.
+
+Return 0 for the handshake to continue or non-zero to terminate.
+*/
+
+static int
+verify_cb(gnutls_session_t session)
+{
+const gnutls_datum_t * cert_list;
+unsigned int cert_list_size = 0;
+gnutls_x509_crt_t crt;
+int rc;
+uschar * yield;
+exim_gnutls_state_st * state = gnutls_session_get_ptr(session);
+
+if ((cert_list = gnutls_certificate_get_peers(session, &cert_list_size)))
+ while (cert_list_size--)
+ {
+ if ((rc = import_cert(&cert_list[cert_list_size], &crt)) != GNUTLS_E_SUCCESS)
+ {
+ DEBUG(D_tls) debug_printf("TLS: peer cert problem: depth %d: %s\n",
+ cert_list_size, gnutls_strerror(rc));
+ break;
+ }
+
+ state->tlsp->peercert = crt;
+ if ((yield = event_raise(state->event_action,
+ US"tls:cert", string_sprintf("%d", cert_list_size), &errno)))
+ {
+ log_write(0, LOG_MAIN,
+ "SSL verify denied by event-action: depth=%d: %s",
+ cert_list_size, yield);
+ return 1; /* reject */
+ }
+ state->tlsp->peercert = NULL;
+ }
+
+return 0;
+}
+
+#endif
+
+
+static gstring *
+ddump(gnutls_datum_t * d)
+{
+gstring * g = string_get((d->size+1) * 2);
+uschar * s = d->data;
+for (unsigned i = d->size; i > 0; i--, s++)
+ {
+ g = string_catn(g, US "0123456789abcdef" + (*s >> 4), 1);
+ g = string_catn(g, US "0123456789abcdef" + (*s & 0xf), 1);
+ }
+return g;
+}
+
+static void
+post_handshake_debug(exim_gnutls_state_st * state)
+{
+#ifdef SUPPORT_GNUTLS_SESS_DESC
+debug_printf("%s\n", gnutls_session_get_desc(state->session));
+#endif
+
+#ifdef SUPPORT_GNUTLS_KEYLOG
+# ifdef EXIM_HAVE_TLS1_3
+if (gnutls_protocol_get_version(state->session) < GNUTLS_TLS1_3)
+# else
+if (TRUE)
+# endif
+ {
+ gnutls_datum_t c, s;
+ gstring * gc, * gs;
+ /* For TLS1.2 we only want the client random and the master secret */
+ gnutls_session_get_random(state->session, &c, &s);
+ gnutls_session_get_master_secret(state->session, &s);
+ gc = ddump(&c);
+ gs = ddump(&s);
+ debug_printf("CLIENT_RANDOM %.*s %.*s\n", (int)gc->ptr, gc->s, (int)gs->ptr, gs->s);
+ }
+else
+ debug_printf("To get keying info for TLS1.3 is hard:\n"
+ " Set environment variable SSLKEYLOGFILE to a filename relative to the spool directory,\n"
+ " and make sure it is writable by the Exim runtime user.\n"
+ " Add SSLKEYLOGFILE to keep_environment in the exim config.\n"
+ " Start Exim as root.\n"
+ " If using sudo, add SSLKEYLOGFILE to env_keep in /etc/sudoers\n"
+ " (works for TLS1.2 also, and saves cut-paste into file).\n"
+ " Trying to use add_environment for this will not work\n");
+#endif
+}
+
+
+#ifdef EXIM_HAVE_TLS_RESUME
+static int
+tls_server_ticket_cb(gnutls_session_t sess, u_int htype, unsigned when,
+ unsigned incoming, const gnutls_datum_t * msg)
+{
+DEBUG(D_tls) debug_printf("newticket cb\n");
+tls_in.resumption |= RESUME_CLIENT_REQUESTED;
+return 0;
+}
+
+static void
+tls_server_resume_prehandshake(exim_gnutls_state_st * state)
+{
+/* Should the server offer session resumption? */
+tls_in.resumption = RESUME_SUPPORTED;
+if (verify_check_host(&tls_resumption_hosts) == OK)
+ {
+ int rc;
+ /* GnuTLS appears to not do ticket overlap, but does emit a fresh ticket when
+ an offered resumption is unacceptable. We lose one resumption per ticket
+ lifetime, and sessions cannot be indefinitely re-used. There seems to be no
+ way (3.6.7) of changing the default number of 2 TLS1.3 tickets issued, but at
+ least they go out in a single packet. */
+
+ if (!(rc = gnutls_session_ticket_enable_server(state->session,
+ &server_sessticket_key)))
+ tls_in.resumption |= RESUME_SERVER_TICKET;
+ else
+ DEBUG(D_tls)
+ debug_printf("enabling session tickets: %s\n", US gnutls_strerror(rc));
+
+ /* Try to tell if we see a ticket request */
+ gnutls_handshake_set_hook_function(state->session,
+ GNUTLS_HANDSHAKE_ANY, GNUTLS_HOOK_POST, tls_server_hook_cb);
+ }
+}
+
+static void
+tls_server_resume_posthandshake(exim_gnutls_state_st * state)
+{
+if (gnutls_session_resumption_requested(state->session))
+ {
+ /* This tells us the client sent a full ticket. We use a
+ callback on session-ticket request, elsewhere, to tell
+ if a client asked for a ticket. */
+
+ tls_in.resumption |= RESUME_CLIENT_SUGGESTED;
+ DEBUG(D_tls) debug_printf("client requested resumption\n");
+ }
+if (gnutls_session_is_resumed(state->session))
+ {
+ tls_in.resumption |= RESUME_USED;
+ DEBUG(D_tls) debug_printf("Session resumed\n");
+ }
+}
+#endif /* EXIM_HAVE_TLS_RESUME */
+
+
+#ifdef EXIM_HAVE_ALPN
+/* Expand and convert an Exim list to a gnutls_datum list. False return for fail.
+NULL plist return for silent no-ALPN.
+*/
+
+static BOOL
+tls_alpn_plist(uschar ** tls_alpn, const gnutls_datum_t ** plist, unsigned * plen,
+ uschar ** errstr)
+{
+uschar * exp_alpn;
+
+if (!expand_check(*tls_alpn, US"tls_alpn", &exp_alpn, errstr))
+ return FALSE;
+
+if (!exp_alpn)
+ {
+ DEBUG(D_tls) debug_printf("Setting TLS ALPN forced to fail, not sending\n");
+ *plist = NULL;
+ }
+else
+ {
+ const uschar * list = exp_alpn;
+ int sep = 0;
+ unsigned cnt = 0;
+ gnutls_datum_t * p;
+ uschar * s;
+
+ while (string_nextinlist(&list, &sep, NULL, 0)) cnt++;
+
+ p = store_get(sizeof(gnutls_datum_t) * cnt, exp_alpn);
+ list = exp_alpn;
+ for (int i = 0; s = string_nextinlist(&list, &sep, NULL, 0); i++)
+ { p[i].data = s; p[i].size = Ustrlen(s); }
+ *plist = (*plen = cnt) ? p : NULL;
+ }
+return TRUE;
+}
+
+static void
+tls_server_set_acceptable_alpns(exim_gnutls_state_st * state, uschar ** errstr)
+{
+uschar * local_alpn = string_copy(tls_alpn);
+int rc;
+const gnutls_datum_t * plist;
+unsigned plen;
+
+if (tls_alpn_plist(&local_alpn, &plist, &plen, errstr) && plist)
+ {
+ /* This seems to be only mandatory if the client sends an ALPN extension;
+ not trying ALPN is ok. Need to decide how to support server-side must-alpn. */
+
+ server_seen_alpn = 0;
+ if (!(rc = gnutls_alpn_set_protocols(state->session, plist, plen,
+ GNUTLS_ALPN_MANDATORY)))
+ gnutls_handshake_set_hook_function(state->session,
+ GNUTLS_HANDSHAKE_ANY, GNUTLS_HOOK_POST, tls_server_hook_cb);
+ else
+ DEBUG(D_tls)
+ debug_printf("setting alpn protocols: %s\n", US gnutls_strerror(rc));
+ }
+}
+#endif /* EXIM_HAVE_ALPN */
+
+/* ------------------------------------------------------------------------ */
+/* Exported functions */
+
+
+
+
+/*************************************************
+* Start a TLS session in a server *
+*************************************************/
+
+/* This is called when Exim is running as a server, after having received
+the STARTTLS command. It must respond to that command, and then negotiate
+a TLS session.
+
+Arguments:
+ errstr pointer to error string
+
+Returns: OK on success
+ DEFER for errors before the start of the negotiation
+ FAIL for errors during the negotiation; the server can't
+ continue running.
+*/
+
+int
+tls_server_start(uschar ** errstr)
+{
+int rc;
+exim_gnutls_state_st * state = NULL;
+
+/* Check for previous activation */
+if (tls_in.active.sock >= 0)
+ {
+ tls_error(US"STARTTLS received after TLS started", US "", NULL, errstr);
+ smtp_printf("554 Already in TLS\r\n", FALSE);
+ return FAIL;
+ }
+
+/* Initialize the library. If it fails, it will already have logged the error
+and sent an SMTP response. */
+
+DEBUG(D_tls) debug_printf("initialising GnuTLS as a server\n");
+
+ {
+#ifdef MEASURE_TIMING
+ struct timeval t0;
+ gettimeofday(&t0, NULL);
+#endif
+
+ if ((rc = tls_init(NULL, NULL,
+ tls_require_ciphers, &state, &tls_in, errstr)) != OK) return rc;
+
+#ifdef MEASURE_TIMING
+ report_time_since(&t0, US"server tls_init (delta)");
+#endif
+ }
+
+#ifdef EXIM_HAVE_ALPN
+tls_server_set_acceptable_alpns(state, errstr);
+#endif
+
+#ifdef EXIM_HAVE_TLS_RESUME
+tls_server_resume_prehandshake(state);
+#endif
+
+/* If this is a host for which certificate verification is mandatory or
+optional, set up appropriately. */
+
+if (verify_check_host(&tls_verify_hosts) == OK)
+ {
+ DEBUG(D_tls)
+ debug_printf("TLS: a client certificate will be required\n");
+ state->verify_requirement = VERIFY_REQUIRED;
+ gnutls_certificate_server_set_request(state->session, GNUTLS_CERT_REQUIRE);
+ }
+else if (verify_check_host(&tls_try_verify_hosts) == OK)
+ {
+ DEBUG(D_tls)
+ debug_printf("TLS: a client certificate will be requested but not required\n");
+ state->verify_requirement = VERIFY_OPTIONAL;
+ gnutls_certificate_server_set_request(state->session, GNUTLS_CERT_REQUEST);
+ }
+else
+ {
+ DEBUG(D_tls)
+ debug_printf("TLS: a client certificate will not be requested\n");
+ state->verify_requirement = VERIFY_NONE;
+ gnutls_certificate_server_set_request(state->session, GNUTLS_CERT_IGNORE);
+ }
+
+#ifndef DISABLE_EVENT
+if (event_action)
+ {
+ state->event_action = event_action;
+ gnutls_session_set_ptr(state->session, state);
+ gnutls_certificate_set_verify_function(state->lib_state.x509_cred, verify_cb);
+ }
+#endif
+
+/* Register SNI handling; always, even if not in tls_certificate, so that the
+expansion variable $tls_sni is always available. */
+
+gnutls_handshake_set_post_client_hello_function(state->session,
+ exim_sni_handling_cb);
+
+/* Set context and tell client to go ahead, except in the case of TLS startup
+on connection, where outputting anything now upsets the clients and tends to
+make them disconnect. We need to have an explicit fflush() here, to force out
+the response. Other smtp_printf() calls do not need it, because in non-TLS
+mode, the fflush() happens when smtp_getc() is called. */
+
+if (!state->tlsp->on_connect)
+ {
+ smtp_printf("220 TLS go ahead\r\n", FALSE);
+ fflush(smtp_out);
+ }
+
+/* Now negotiate the TLS session. We put our own timer on it, since it seems
+that the GnuTLS library doesn't.
+From 3.1.0 there is gnutls_handshake_set_timeout() - but it requires you
+to set (and clear down afterwards) up a pull-timeout callback function that does
+a select, so we're no better off unless avoiding signals becomes an issue. */
+
+gnutls_transport_set_ptr2(state->session,
+ (gnutls_transport_ptr_t)(long) fileno(smtp_in),
+ (gnutls_transport_ptr_t)(long) fileno(smtp_out));
+state->fd_in = fileno(smtp_in);
+state->fd_out = fileno(smtp_out);
+
+sigalrm_seen = FALSE;
+if (smtp_receive_timeout > 0) ALARM(smtp_receive_timeout);
+do
+ rc = gnutls_handshake(state->session);
+while (rc == GNUTLS_E_AGAIN || rc == GNUTLS_E_INTERRUPTED && !sigalrm_seen);
+ALARM_CLR(0);
+
+if (rc != GNUTLS_E_SUCCESS)
+ {
+ DEBUG(D_tls) debug_printf(" error %d from gnutls_handshake: %s\n",
+ rc, gnutls_strerror(rc));
+
+ /* It seems that, except in the case of a timeout, we have to close the
+ connection right here; otherwise if the other end is running OpenSSL it hangs
+ until the server times out. */
+
+ if (sigalrm_seen)
+ {
+ tls_error(US"gnutls_handshake", US"timed out", NULL, errstr);
+#ifndef DISABLE_EVENT
+ (void) event_raise(event_action, US"tls:fail:connect", *errstr, NULL);
+#endif
+ gnutls_db_remove_session(state->session);
+ }
+ else
+ {
+ tls_error_gnu(state, US"gnutls_handshake", rc, errstr);
+#ifndef DISABLE_EVENT
+ (void) event_raise(event_action, US"tls:fail:connect", *errstr, NULL);
+#endif
+ (void) gnutls_alert_send_appropriate(state->session, rc);
+ gnutls_deinit(state->session);
+ millisleep(500);
+ shutdown(state->fd_out, SHUT_WR);
+ for (int i = 1024; fgetc(smtp_in) != EOF && i > 0; ) i--; /* drain skt */
+ (void)fclose(smtp_out);
+ (void)fclose(smtp_in);
+ smtp_out = smtp_in = NULL;
+ }
+
+ return FAIL;
+ }
+
+#ifdef GNUTLS_SFLAGS_EXT_MASTER_SECRET
+if (gnutls_session_get_flags(state->session) & GNUTLS_SFLAGS_EXT_MASTER_SECRET)
+ tls_in.ext_master_secret = TRUE;
+#endif
+
+#ifdef EXIM_HAVE_TLS_RESUME
+tls_server_resume_posthandshake(state);
+#endif
+
+DEBUG(D_tls) post_handshake_debug(state);
+
+#ifdef EXIM_HAVE_ALPN
+if (server_seen_alpn > 0)
+ {
+ DEBUG(D_tls)
+ { /* The client offered ALPN. See what was negotiated. */
+ gnutls_datum_t p = {.size = 0};
+ int rc = gnutls_alpn_get_selected_protocol(state->session, &p);
+ if (!rc)
+ debug_printf("ALPN negotiated: %.*s\n", (int)p.size, p.data);
+ else
+ debug_printf("getting alpn protocol: %s\n", US gnutls_strerror(rc));
+
+ }
+ }
+else if (server_seen_alpn == 0)
+ if (verify_check_host(&hosts_require_alpn) == OK)
+ {
+ gnutls_alert_send(state->session, GNUTLS_AL_FATAL, GNUTLS_A_NO_APPLICATION_PROTOCOL);
+ tls_error(US"handshake", US"ALPN required but not negotiated", NULL, errstr);
+ return FAIL;
+ }
+ else
+ DEBUG(D_tls) debug_printf("TLS: no ALPN presented in handshake\n");
+else
+ DEBUG(D_tls) debug_printf("TLS: was not watching for ALPN\n");
+#endif
+
+/* Verify after the fact */
+
+if (!verify_certificate(state, errstr))
+ {
+ if (state->verify_requirement != VERIFY_OPTIONAL)
+ {
+ (void) tls_error(US"certificate verification failed", *errstr, NULL, errstr);
+ return FAIL;
+ }
+ DEBUG(D_tls)
+ debug_printf("TLS: continuing on only because verification was optional, after: %s\n",
+ *errstr);
+ }
+
+/* Sets various Exim expansion variables; always safe within server */
+
+extract_exim_vars_from_tls_state(state);
+
+/* TLS has been set up. Adjust the input functions to read via TLS,
+and initialize appropriately. */
+
+state->xfer_buffer = store_malloc(ssl_xfer_buffer_size);
+
+receive_getc = tls_getc;
+receive_getbuf = tls_getbuf;
+receive_get_cache = tls_get_cache;
+receive_hasc = tls_hasc;
+receive_ungetc = tls_ungetc;
+receive_feof = tls_feof;
+receive_ferror = tls_ferror;
+
+return OK;
+}
+
+
+
+
+static void
+tls_client_setup_hostname_checks(host_item * host, exim_gnutls_state_st * state,
+ smtp_transport_options_block * ob)
+{
+if (verify_check_given_host(CUSS &ob->tls_verify_cert_hostnames, host) == OK)
+ {
+ state->exp_tls_verify_cert_hostnames =
+#ifdef SUPPORT_I18N
+ string_domain_utf8_to_alabel(host->certname, NULL);
+#else
+ host->certname;
+#endif
+ DEBUG(D_tls)
+ debug_printf("TLS: server cert verification includes hostname: \"%s\"\n",
+ state->exp_tls_verify_cert_hostnames);
+ }
+}
+
+
+
+
+#ifdef SUPPORT_DANE
+/* Given our list of RRs from the TLSA lookup, build a lookup block in
+GnuTLS-DANE's preferred format. Hang it on the state str for later
+use in DANE verification.
+
+We point at the dnsa data not copy it, so it must remain valid until
+after verification is done.*/
+
+static BOOL
+dane_tlsa_load(exim_gnutls_state_st * state, dns_answer * dnsa)
+{
+dns_scan dnss;
+int i;
+const char ** dane_data;
+int * dane_data_len;
+
+i = 1;
+for (dns_record * rr = dns_next_rr(dnsa, &dnss, RESET_ANSWERS); rr;
+ rr = dns_next_rr(dnsa, &dnss, RESET_NEXT)
+ ) if (rr->type == T_TLSA) i++;
+
+dane_data = store_get(i * sizeof(uschar *), GET_UNTAINTED);
+dane_data_len = store_get(i * sizeof(int), GET_UNTAINTED);
+
+i = 0;
+for (dns_record * rr = dns_next_rr(dnsa, &dnss, RESET_ANSWERS); rr;
+ rr = dns_next_rr(dnsa, &dnss, RESET_NEXT)
+ ) if (rr->type == T_TLSA && rr->size > 3)
+ {
+ const uschar * p = rr->data;
+/*XXX need somehow to mark rr and its data as tainted. Doues this mean copying it? */
+ uint8_t usage = p[0], sel = p[1], type = p[2];
+
+ DEBUG(D_tls)
+ debug_printf("TLSA: %d %d %d size %d\n", usage, sel, type, rr->size);
+
+ if ( (usage != DANESSL_USAGE_DANE_TA && usage != DANESSL_USAGE_DANE_EE)
+ || (sel != 0 && sel != 1)
+ )
+ continue;
+ switch(type)
+ {
+ case 0: /* Full: cannot check at present */
+ break;
+ case 1: if (rr->size != 3 + 256/8) continue; /* sha2-256 */
+ break;
+ case 2: if (rr->size != 3 + 512/8) continue; /* sha2-512 */
+ break;
+ default: continue;
+ }
+
+ tls_out.tlsa_usage |= 1<<usage;
+ dane_data[i] = CS p;
+ dane_data_len[i++] = rr->size;
+ }
+
+if (!i) return FALSE;
+
+dane_data[i] = NULL;
+dane_data_len[i] = 0;
+
+state->dane_data = (char * const *)dane_data;
+state->dane_data_len = dane_data_len;
+return TRUE;
+}
+#endif
+
+
+
+#ifdef EXIM_HAVE_TLS_RESUME
+/* On the client, get any stashed session for the given IP from hints db
+and apply it to the ssl-connection for attempted resumption. Although
+there is a gnutls_session_ticket_enable_client() interface it is
+documented as unnecessary (as of 3.6.7) as "session tickets are emabled
+by deafult". There seems to be no way to disable them, so even hosts not
+enabled by the transport option will be sent a ticket request. We will
+however avoid storing and retrieving session information. */
+
+static void
+tls_retrieve_session(tls_support * tlsp, gnutls_session_t session,
+ smtp_connect_args * conn_args, smtp_transport_options_block * ob)
+{
+tlsp->resumption = RESUME_SUPPORTED;
+
+if (!conn_args->have_lbserver)
+ { DEBUG(D_tls) debug_printf("resumption not supported on continued-connection\n"); }
+else if (verify_check_given_host(CUSS &ob->tls_resumption_hosts, conn_args->host) == OK)
+ {
+ dbdata_tls_session * dt;
+ int len, rc;
+ open_db dbblock, * dbm_file;
+
+ tlsp->host_resumable = TRUE;
+ tls_client_resmption_key(tlsp, conn_args, ob);
+
+ tlsp->resumption |= RESUME_CLIENT_REQUESTED;
+ if ((dbm_file = dbfn_open(US"tls", O_RDONLY, &dbblock, FALSE, FALSE)))
+ {
+ /* We'd like to filter the retrieved session for ticket advisory expiry,
+ but 3.6.1 seems to give no access to that */
+
+ if ((dt = dbfn_read_with_length(dbm_file, tlsp->resume_index, &len)))
+ if (!(rc = gnutls_session_set_data(session,
+ CUS dt->session, (size_t)len - sizeof(dbdata_tls_session))))
+ {
+ DEBUG(D_tls) debug_printf("good session\n");
+ tlsp->resumption |= RESUME_CLIENT_SUGGESTED;
+ }
+ else DEBUG(D_tls) debug_printf("setting session resumption data: %s\n",
+ US gnutls_strerror(rc));
+ dbfn_close(dbm_file);
+ }
+ }
+}
+
+
+static void
+tls_save_session(tls_support * tlsp, gnutls_session_t session, const host_item * host)
+{
+/* TLS 1.2 - we get both the callback and the direct posthandshake call,
+but this flag is not set until the second. TLS 1.3 it's the other way about.
+Keep both calls as the session data cannot be extracted before handshake
+completes. */
+
+if (gnutls_session_get_flags(session) & GNUTLS_SFLAGS_SESSION_TICKET)
+ {
+ gnutls_datum_t tkt;
+ int rc;
+
+ DEBUG(D_tls) debug_printf("server offered session ticket\n");
+ tlsp->ticket_received = TRUE;
+ tlsp->resumption |= RESUME_SERVER_TICKET;
+
+ if (tlsp->host_resumable)
+ if (!(rc = gnutls_session_get_data2(session, &tkt)))
+ {
+ open_db dbblock, * dbm_file;
+ int dlen = sizeof(dbdata_tls_session) + tkt.size;
+ dbdata_tls_session * dt = store_get(dlen, GET_TAINTED);
+
+ DEBUG(D_tls) debug_printf("session data size %u\n", (unsigned)tkt.size);
+ memcpy(dt->session, tkt.data, tkt.size);
+ gnutls_free(tkt.data);
+
+ if ((dbm_file = dbfn_open(US"tls", O_RDWR, &dbblock, FALSE, FALSE)))
+ {
+ /* key for the db is the IP */
+ dbfn_write(dbm_file, tlsp->resume_index, dt, dlen);
+ dbfn_close(dbm_file);
+
+ DEBUG(D_tls)
+ debug_printf("wrote session db (len %u)\n", (unsigned)dlen);
+ }
+ }
+ else DEBUG(D_tls)
+ debug_printf("extract session data: %s\n", US gnutls_strerror(rc));
+ }
+}
+
+
+/* With a TLS1.3 session, the ticket(s) are not seen until
+the first data read is attempted. And there's often two of them.
+Pick them up with this callback. We are also called for 1.2
+but we do nothing.
+*/
+static int
+tls_client_ticket_cb(gnutls_session_t sess, u_int htype, unsigned when,
+ unsigned incoming, const gnutls_datum_t * msg)
+{
+exim_gnutls_state_st * state = gnutls_session_get_ptr(sess);
+tls_support * tlsp = state->tlsp;
+
+DEBUG(D_tls) debug_printf("newticket cb\n");
+
+if (!tlsp->ticket_received)
+ tls_save_session(tlsp, sess, state->host);
+return 0;
+}
+
+
+static void
+tls_client_resume_prehandshake(exim_gnutls_state_st * state,
+ tls_support * tlsp, smtp_connect_args * conn_args,
+ smtp_transport_options_block * ob)
+{
+gnutls_session_set_ptr(state->session, state);
+gnutls_handshake_set_hook_function(state->session,
+ GNUTLS_HANDSHAKE_NEW_SESSION_TICKET, GNUTLS_HOOK_POST, tls_client_ticket_cb);
+
+tls_retrieve_session(tlsp, state->session, conn_args, ob);
+}
+
+static void
+tls_client_resume_posthandshake(exim_gnutls_state_st * state,
+ tls_support * tlsp, host_item * host)
+{
+if (gnutls_session_is_resumed(state->session))
+ {
+ DEBUG(D_tls) debug_printf("Session resumed\n");
+ tlsp->resumption |= RESUME_USED;
+ }
+
+tls_save_session(tlsp, state->session, host);
+}
+#endif /* !DISABLE_TLS_RESUME */
+
+
+/*************************************************
+* Start a TLS session in a client *
+*************************************************/
+
+/* Called from the smtp transport after STARTTLS has been accepted.
+
+Arguments:
+ cctx connection context
+ conn_args connection details
+ cookie datum for randomness (not used)
+ tlsp record details of channel configuration here; must be non-NULL
+ errstr error string pointer
+
+Returns: TRUE for success with TLS session context set in smtp context,
+ FALSE on error
+*/
+
+BOOL
+tls_client_start(client_conn_ctx * cctx, smtp_connect_args * conn_args,
+ void * cookie ARG_UNUSED,
+ tls_support * tlsp, uschar ** errstr)
+{
+host_item * host = conn_args->host; /* for msgs and option-tests */
+transport_instance * tb = conn_args->tblock; /* always smtp or NULL */
+smtp_transport_options_block * ob = tb
+ ? (smtp_transport_options_block *)tb->options_block
+ : &smtp_transport_option_defaults;
+int rc;
+exim_gnutls_state_st * state = NULL;
+uschar * cipher_list = NULL;
-/* Check for previous activation */
+#ifndef DISABLE_OCSP
+BOOL require_ocsp =
+ verify_check_given_host(CUSS &ob->hosts_require_ocsp, host) == OK;
+BOOL request_ocsp = require_ocsp ? TRUE
+ : verify_check_given_host(CUSS &ob->hosts_request_ocsp, host) == OK;
+#endif
+
+DEBUG(D_tls) debug_printf("initialising GnuTLS as a client on fd %d\n", cctx->sock);
-if (tls_active >= 0)
+#ifdef SUPPORT_DANE
+/* If dane is flagged, have either request or require dane for this host, and
+a TLSA record found. Therefore, dane verify required. Which implies cert must
+be requested and supplied, dane verify must pass, and cert verify irrelevant
+(incl. hostnames), and (caller handled) require_tls and sni=$domain */
+
+if (conn_args->dane && ob->dane_require_tls_ciphers)
{
- log_write(0, LOG_MAIN, "STARTTLS received in already encrypted "
- "connection from %s",
- (sender_fullhost != NULL)? sender_fullhost : US"local process");
- smtp_printf("554 Already in TLS\r\n");
- return FAIL;
+ /* not using Expand_check_tlsvar because not yet in state */
+ if (!expand_check(ob->dane_require_tls_ciphers, US"dane_require_tls_ciphers",
+ &cipher_list, errstr))
+ return FALSE;
+ cipher_list = cipher_list && *cipher_list
+ ? ob->dane_require_tls_ciphers : ob->tls_require_ciphers;
}
+#endif
-/* Initialize the library. If it fails, it will already have logged the error
-and sent an SMTP response. */
+if (!cipher_list)
+ cipher_list = ob->tls_require_ciphers;
-DEBUG(D_tls) debug_printf("initializing GnuTLS as a server\n");
+ {
+#ifdef MEASURE_TIMING
+ struct timeval t0;
+ gettimeofday(&t0, NULL);
+#endif
-rc = tls_init(NULL, tls_certificate, tls_privatekey, tls_verify_certificates,
- tls_crl);
-if (rc != OK) return rc;
+ if (tls_init(host, ob, cipher_list, &state, tlsp, errstr) != OK)
+ return FALSE;
-if (!expand_check(require_ciphers, US"tls_require_ciphers", &expciphers) ||
- !expand_check(require_mac, US"gnutls_require_mac", &expmac) ||
- !expand_check(require_kx, US"gnutls_require_kx", &expkx) ||
- !expand_check(require_proto, US"gnutls_require_proto", &expproto))
- return FAIL;
+#ifdef MEASURE_TIMING
+ report_time_since(&t0, US"client tls_init (delta)");
+#endif
+ }
-/* If this is a host for which certificate verification is mandatory or
-optional, set up appropriately. */
+if (ob->tls_alpn)
+#ifdef EXIM_HAVE_ALPN
+ {
+ const gnutls_datum_t * plist;
+ unsigned plen;
-tls_certificate_verified = FALSE;
-verify_requirement = VERIFY_NONE;
+ if (!tls_alpn_plist(&ob->tls_alpn, &plist, &plen, errstr))
+ return FALSE;
+ if (plist)
+ if (gnutls_alpn_set_protocols(state->session, plist, plen, 0) != 0)
+ {
+ tls_error(US"alpn init", NULL, state->host, errstr);
+ return FALSE;
+ }
+ else
+ DEBUG(D_tls) debug_printf("Setting TLS ALPN '%s'\n", ob->tls_alpn);
+ }
+#else
+ log_write(0, LOG_MAIN, "ALPN unusable with this GnuTLS library version; ignoring \"%s\"\n",
+ ob->tls_alpn);
+#endif
-if (verify_check_host(&tls_verify_hosts) == OK)
- verify_requirement = VERIFY_REQUIRED;
-else if (verify_check_host(&tls_try_verify_hosts) == OK)
- verify_requirement = VERIFY_OPTIONAL;
+ {
+ int dh_min_bits = ob->tls_dh_min_bits;
+ if (dh_min_bits < EXIM_CLIENT_DH_MIN_MIN_BITS)
+ {
+ DEBUG(D_tls)
+ debug_printf("WARNING: tls_dh_min_bits far too low,"
+ " clamping %d up to %d\n",
+ dh_min_bits, EXIM_CLIENT_DH_MIN_MIN_BITS);
+ dh_min_bits = EXIM_CLIENT_DH_MIN_MIN_BITS;
+ }
-/* Prepare for new connection */
+ DEBUG(D_tls) debug_printf("Setting D-H prime minimum"
+ " acceptable bits to %d\n",
+ dh_min_bits);
+ gnutls_dh_set_prime_bits(state->session, dh_min_bits);
+ }
-tls_session = tls_session_init(GNUTLS_SERVER, expciphers, expmac, expkx,
- expproto);
-if (tls_session == NULL)
- return tls_error(US"tls_session_init", NULL, GNUTLS_E_MEMORY_ERROR);
+/* Stick to the old behaviour for compatibility if tls_verify_certificates is
+set but both tls_verify_hosts and tls_try_verify_hosts are unset. Check only
+the specified host patterns if one of them is defined */
-/* Set context and tell client to go ahead, except in the case of TLS startup
-on connection, where outputting anything now upsets the clients and tends to
-make them disconnect. We need to have an explicit fflush() here, to force out
-the response. Other smtp_printf() calls do not need it, because in non-TLS
-mode, the fflush() happens when smtp_getc() is called. */
+#ifdef SUPPORT_DANE
+if (conn_args->dane && dane_tlsa_load(state, &conn_args->tlsa_dnsa))
+ {
+ DEBUG(D_tls)
+ debug_printf("TLS: server certificate DANE required\n");
+ state->verify_requirement = VERIFY_DANE;
+ gnutls_certificate_server_set_request(state->session, GNUTLS_CERT_REQUIRE);
+ }
+else
+#endif
+ if ( ( state->exp_tls_verify_certificates
+ && !ob->tls_verify_hosts
+ && (!ob->tls_try_verify_hosts || !*ob->tls_try_verify_hosts)
+ )
+ || verify_check_given_host(CUSS &ob->tls_verify_hosts, host) == OK
+ )
+ {
+ tls_client_setup_hostname_checks(host, state, ob);
+ DEBUG(D_tls)
+ debug_printf("TLS: server certificate verification required\n");
+ state->verify_requirement = VERIFY_REQUIRED;
+ gnutls_certificate_server_set_request(state->session, GNUTLS_CERT_REQUIRE);
+ }
+else if (verify_check_given_host(CUSS &ob->tls_try_verify_hosts, host) == OK)
+ {
+ tls_client_setup_hostname_checks(host, state, ob);
+ DEBUG(D_tls)
+ debug_printf("TLS: server certificate verification optional\n");
+ state->verify_requirement = VERIFY_OPTIONAL;
+ gnutls_certificate_server_set_request(state->session, GNUTLS_CERT_REQUEST);
+ }
+else
+ {
+ DEBUG(D_tls)
+ debug_printf("TLS: server certificate verification not required\n");
+ state->verify_requirement = VERIFY_NONE;
+ gnutls_certificate_server_set_request(state->session, GNUTLS_CERT_IGNORE);
+ }
-if (!tls_on_connect)
+#ifndef DISABLE_OCSP
+ /* supported since GnuTLS 3.1.3 */
+if (request_ocsp)
{
- smtp_printf("220 TLS go ahead\r\n");
- fflush(smtp_out);
+ DEBUG(D_tls) debug_printf("TLS: will request OCSP stapling\n");
+ if ((rc = gnutls_ocsp_status_request_enable_client(state->session,
+ NULL, 0, NULL)) != OK)
+ {
+ tls_error_gnu(state, US"cert-status-req", rc, errstr);
+ return FALSE;
+ }
+ tlsp->ocsp = OCSP_NOT_RESP;
}
+#endif
-/* Now negotiate the TLS session. We put our own timer on it, since it seems
-that the GnuTLS library doesn't. */
+#ifdef EXIM_HAVE_TLS_RESUME
+tls_client_resume_prehandshake(state, tlsp, conn_args, ob);
+#endif
+
+#ifndef DISABLE_EVENT
+if (tb && tb->event_action)
+ {
+ state->event_action = tb->event_action;
+ gnutls_session_set_ptr(state->session, state);
+ gnutls_certificate_set_verify_function(state->lib_state.x509_cred, verify_cb);
+ }
+#endif
+
+gnutls_transport_set_ptr(state->session, (gnutls_transport_ptr_t)(long) cctx->sock);
+state->fd_in = cctx->sock;
+state->fd_out = cctx->sock;
-gnutls_transport_set_ptr2(tls_session, (gnutls_transport_ptr)fileno(smtp_in),
- (gnutls_transport_ptr)fileno(smtp_out));
+DEBUG(D_tls) debug_printf("about to gnutls_handshake\n");
+/* There doesn't seem to be a built-in timeout on connection. */
sigalrm_seen = FALSE;
-if (smtp_receive_timeout > 0) alarm(smtp_receive_timeout);
-rc = gnutls_handshake(tls_session);
-alarm(0);
+ALARM(ob->command_timeout);
+do
+ rc = gnutls_handshake(state->session);
+while (rc == GNUTLS_E_AGAIN || rc == GNUTLS_E_INTERRUPTED && !sigalrm_seen);
+ALARM_CLR(0);
-if (rc < 0)
+if (rc != GNUTLS_E_SUCCESS)
{
if (sigalrm_seen)
- Ustrcpy(ssl_errstring, "timed out");
+ {
+ gnutls_alert_send(state->session, GNUTLS_AL_FATAL, GNUTLS_A_USER_CANCELED);
+ tls_error(US"gnutls_handshake", US"timed out", state->host, errstr);
+ }
else
- Ustrcpy(ssl_errstring, gnutls_strerror(rc));
- log_write(0, LOG_MAIN,
- "TLS error on connection from %s (gnutls_handshake): %s",
- (sender_fullhost != NULL)? sender_fullhost : US"local process",
- ssl_errstring);
+ tls_error_gnu(state, US"gnutls_handshake", rc, errstr);
+ return FALSE;
+ }
- /* It seems that, except in the case of a timeout, we have to close the
- connection right here; otherwise if the other end is running OpenSSL it hangs
- until the server times out. */
+DEBUG(D_tls) post_handshake_debug(state);
- if (!sigalrm_seen)
- {
- (void)fclose(smtp_out);
- (void)fclose(smtp_in);
- }
+/* Verify late */
- return FAIL;
+if (!verify_certificate(state, errstr))
+ {
+ tls_error(US"certificate verification failed", *errstr, state->host, errstr);
+ return FALSE;
}
-DEBUG(D_tls) debug_printf("gnutls_handshake was successful\n");
+#ifdef GNUTLS_SFLAGS_EXT_MASTER_SECRET
+if (gnutls_session_get_flags(state->session) & GNUTLS_SFLAGS_EXT_MASTER_SECRET)
+ tlsp->ext_master_secret = TRUE;
+#endif
-if (verify_requirement != VERIFY_NONE &&
- !verify_certificate(tls_session, &error))
+#ifndef DISABLE_OCSP
+if (request_ocsp)
{
- log_write(0, LOG_MAIN,
- "TLS error on connection from %s: certificate verification failed (%s)",
- (sender_fullhost != NULL)? sender_fullhost : US"local process", error);
- return FAIL;
+ DEBUG(D_tls)
+ {
+ gnutls_datum_t stapling;
+ gnutls_ocsp_resp_t resp;
+ gnutls_datum_t printed;
+ unsigned idx = 0;
+
+ for (;
+# ifdef GNUTLS_OCSP_STATUS_REQUEST_GET2
+ (rc = gnutls_ocsp_status_request_get2(state->session, idx, &stapling)) == 0;
+#else
+ (rc = gnutls_ocsp_status_request_get(state->session, &stapling)) == 0;
+#endif
+ idx++)
+ if ( (rc= gnutls_ocsp_resp_init(&resp)) == 0
+ && (rc= gnutls_ocsp_resp_import(resp, &stapling)) == 0
+ && (rc= gnutls_ocsp_resp_print(resp, GNUTLS_OCSP_PRINT_COMPACT, &printed)) == 0
+ )
+ {
+ debug_printf("%.4096s", printed.data);
+ gnutls_free(printed.data);
+ }
+ else
+ (void) tls_error_gnu(state, US"ocsp decode", rc, errstr);
+ if (idx == 0 && rc)
+ (void) tls_error_gnu(state, US"ocsp decode", rc, errstr);
+ }
+
+ if (gnutls_ocsp_status_request_is_checked(state->session, 0) == 0)
+ {
+ tlsp->ocsp = OCSP_FAILED;
+ tls_error(US"certificate status check failed", NULL, state->host, errstr);
+ if (require_ocsp)
+ return FALSE;
+ }
+ else
+ {
+ DEBUG(D_tls) debug_printf("Passed OCSP checking\n");
+ tlsp->ocsp = OCSP_VFIED;
+ }
}
+#endif
-construct_cipher_name(tls_session);
+#ifdef EXIM_HAVE_TLS_RESUME
+tls_client_resume_posthandshake(state, tlsp, host);
+#endif
-/* TLS has been set up. Adjust the input functions to read via TLS,
-and initialize appropriately. */
+#ifdef EXIM_HAVE_ALPN
+if (ob->tls_alpn) /* We requested. See what was negotiated. */
+ {
+ gnutls_datum_t p = {.size = 0};
-ssl_xfer_buffer = store_malloc(ssl_xfer_buffer_size);
-ssl_xfer_buffer_lwm = ssl_xfer_buffer_hwm = 0;
-ssl_xfer_eof = ssl_xfer_error = 0;
+ if (gnutls_alpn_get_selected_protocol(state->session, &p) == 0)
+ { DEBUG(D_tls) debug_printf("ALPN negotiated: '%.*s'\n", (int)p.size, p.data); }
+ else if (verify_check_given_host(CUSS &ob->hosts_require_alpn, host) == OK)
+ {
+ gnutls_alert_send(state->session, GNUTLS_AL_FATAL, GNUTLS_A_NO_APPLICATION_PROTOCOL);
+ tls_error(US"handshake", US"ALPN required but not negotiated", state->host, errstr);
+ return FALSE;
+ }
+ else
+ DEBUG(D_tls) debug_printf("No ALPN negotiated");
+ }
+#endif
-receive_getc = tls_getc;
-receive_ungetc = tls_ungetc;
-receive_feof = tls_feof;
-receive_ferror = tls_ferror;
-receive_smtp_buffered = tls_smtp_buffered;
+/* Sets various Exim expansion variables; may need to adjust for ACL callouts */
-tls_active = fileno(smtp_out);
+extract_exim_vars_from_tls_state(state);
-return OK;
+cctx->tls_ctx = state;
+return TRUE;
}
-/*************************************************
-* Start a TLS session in a client *
-*************************************************/
-
-/* Called from the smtp transport after STARTTLS has been accepted.
-
+/*
Arguments:
- fd the fd of the connection
- host connected host (for messages)
- addr the first address (not used)
- dhparam DH parameter file
- certificate certificate file
- privatekey private key file
- verify_certs file for certificate verify
- verify_crl CRL for verify
- require_ciphers list of allowed ciphers or NULL
- require_mac list of allowed MACs or NULL
- require_kx list of allowed key_exchange methods or NULL
- require_proto list of allowed protocols or NULL
- timeout startup timeout
-
-Returns: OK/DEFER/FAIL (because using common functions),
- but for a client, DEFER and FAIL have the same meaning
+ ct_ctx client TLS context pointer, or NULL for the one global server context
*/
-int
-tls_client_start(int fd, host_item *host, address_item *addr, uschar *dhparam,
- uschar *certificate, uschar *privatekey, uschar *verify_certs,
- uschar *verify_crl, uschar *require_ciphers, uschar *require_mac,
- uschar *require_kx, uschar *require_proto, int timeout)
+void
+tls_shutdown_wr(void * ct_ctx)
{
-const gnutls_datum *server_certs;
-uschar *expciphers = NULL;
-uschar *expmac = NULL;
-uschar *expkx = NULL;
-uschar *expproto = NULL;
-uschar *error;
-unsigned int server_certs_size;
-int rc;
+exim_gnutls_state_st * state = ct_ctx ? ct_ctx : &state_server;
+tls_support * tlsp = state->tlsp;
-DEBUG(D_tls) debug_printf("initializing GnuTLS as a client\n");
+if (!tlsp || tlsp->active.sock < 0) return; /* TLS was not active */
-client_host = host;
-verify_requirement = (verify_certs == NULL)? VERIFY_NONE : VERIFY_REQUIRED;
-rc = tls_init(host, certificate, privatekey, verify_certs, verify_crl);
-if (rc != OK) return rc;
+tls_write(ct_ctx, NULL, 0, FALSE); /* flush write buffer */
-if (!expand_check(require_ciphers, US"tls_require_ciphers", &expciphers) ||
- !expand_check(require_mac, US"gnutls_require_mac", &expmac) ||
- !expand_check(require_kx, US"gnutls_require_kx", &expkx) ||
- !expand_check(require_proto, US"gnutls_require_proto", &expproto))
- return FAIL;
+HDEBUG(D_transport|D_tls|D_acl|D_v) debug_printf_indent(" SMTP(TLS shutdown)>>\n");
+gnutls_bye(state->session, GNUTLS_SHUT_WR);
+}
-tls_session = tls_session_init(GNUTLS_CLIENT, expciphers, expmac, expkx,
- expproto);
+/*************************************************
+* Close down a TLS session *
+*************************************************/
-if (tls_session == NULL)
- return tls_error(US "tls_session_init", host, GNUTLS_E_MEMORY_ERROR);
+/* This is also called from within a delivery subprocess forked from the
+daemon, to shut down the TLS library, without actually doing a shutdown (which
+would tamper with the TLS session in the parent process).
-gnutls_transport_set_ptr(tls_session, (gnutls_transport_ptr)fd);
+Arguments:
+ ct_ctx client context pointer, or NULL for the one global server context
+ do_shutdown 0 no data-flush or TLS close-alert
+ 1 if TLS close-alert is to be sent,
+ 2 if also response to be waited for (2s timeout)
-/* There doesn't seem to be a built-in timeout on connection. */
+Returns: nothing
+*/
-sigalrm_seen = FALSE;
-alarm(timeout);
-rc = gnutls_handshake(tls_session);
-alarm(0);
+void
+tls_close(void * ct_ctx, int do_shutdown)
+{
+exim_gnutls_state_st * state = ct_ctx ? ct_ctx : &state_server;
+tls_support * tlsp = state->tlsp;
-if (rc < 0)
+if (!tlsp || tlsp->active.sock < 0) return; /* TLS was not active */
+
+if (do_shutdown)
{
- if (sigalrm_seen)
- {
- log_write(0, LOG_MAIN, "TLS error on connection to %s [%s]: "
- "gnutls_handshake timed out", host->name, host->address);
- return FAIL;
- }
- else return tls_error(US "gnutls_handshake", host, rc);
- }
+ DEBUG(D_tls) debug_printf("tls_close(): shutting down TLS%s\n",
+ do_shutdown > TLS_SHUTDOWN_NOWAIT ? " (with response-wait)" : "");
-server_certs = gnutls_certificate_get_peers(tls_session, &server_certs_size);
+ tls_write(ct_ctx, NULL, 0, FALSE); /* flush write buffer */
-if (server_certs != NULL)
- {
- uschar buff[1024];
- gnutls_x509_crt gcert;
+#ifdef EXIM_TCP_CORK
+ if (do_shutdown == TLS_SHUTDOWN_WAIT)
+ (void) setsockopt(tlsp->active.sock, IPPROTO_TCP, EXIM_TCP_CORK, US &off, sizeof(off));
+#endif
- gnutls_x509_crt_init(&gcert);
- tls_peerdn = US"unknown";
+ /* The library seems to have no way to only wait for a peer's
+ shutdown, so handle the same as TLS_SHUTDOWN_WAIT */
- if (gnutls_x509_crt_import(gcert, server_certs, GNUTLS_X509_FMT_DER) == 0)
- {
- size_t bufsize = sizeof(buff);
- if (gnutls_x509_crt_get_dn(gcert, CS buff, &bufsize) >= 0)
- tls_peerdn = string_copy_malloc(buff);
- }
+ ALARM(2);
+ gnutls_bye(state->session,
+ do_shutdown > TLS_SHUTDOWN_NOWAIT ? GNUTLS_SHUT_RDWR : GNUTLS_SHUT_WR);
+ ALARM_CLR(0);
}
-/* Should we also verify the hostname here? */
-
-if (verify_requirement != VERIFY_NONE &&
- !verify_certificate(tls_session, &error))
+if (!ct_ctx) /* server */
{
- log_write(0, LOG_MAIN,
- "TLS error on connection to %s [%s]: certificate verification failed (%s)",
- host->name, host->address, error);
- return FAIL;
+ receive_getc = smtp_getc;
+ receive_getbuf = smtp_getbuf;
+ receive_get_cache = smtp_get_cache;
+ receive_hasc = smtp_hasc;
+ receive_ungetc = smtp_ungetc;
+ receive_feof = smtp_feof;
+ receive_ferror = smtp_ferror;
}
-construct_cipher_name(tls_session); /* Sets tls_cipher */
-tls_active = fd;
-return OK;
-}
-
+gnutls_deinit(state->session);
+tlsp->active.sock = -1;
+tlsp->active.tls_ctx = NULL;
+/* Leave bits, peercert, cipher, peerdn, certificate_verified set, for logging */
+tlsp->channelbinding = NULL;
-/*************************************************
-* Deal with logging errors during I/O *
-*************************************************/
+if (state->xfer_buffer) store_free(state->xfer_buffer);
+}
-/* We have to get the identity of the peer from saved data.
-Argument:
- ec the GnuTLS error code, or 0 if it's a local error
- when text identifying read or write
- text local error text when ec is 0
-Returns: nothing
-*/
-static void
-record_io_error(int ec, uschar *when, uschar *text)
+static BOOL
+tls_refill(unsigned lim)
{
-uschar *additional = US"";
+exim_gnutls_state_st * state = &state_server;
+ssize_t inbytes;
-if (ec == GNUTLS_E_FATAL_ALERT_RECEIVED)
- additional = string_sprintf(": %s",
- gnutls_alert_get_name(gnutls_alert_get(tls_session)));
+DEBUG(D_tls) debug_printf("Calling gnutls_record_recv(session=%p, buffer=%p, buffersize=%u)\n",
+ state->session, state->xfer_buffer, ssl_xfer_buffer_size);
-if (initialized == INITIALIZED_SERVER)
- log_write(0, LOG_MAIN, "TLS %s error on connection from %s: %s%s", when,
- (sender_fullhost != NULL)? sender_fullhost : US "local process",
- (ec == 0)? text : US gnutls_strerror(ec), additional);
+sigalrm_seen = FALSE;
+if (smtp_receive_timeout > 0) ALARM(smtp_receive_timeout);
+
+errno = 0;
+do
+ inbytes = gnutls_record_recv(state->session, state->xfer_buffer,
+ MIN(ssl_xfer_buffer_size, lim));
+while (inbytes == GNUTLS_E_AGAIN);
+
+if (smtp_receive_timeout > 0) ALARM_CLR(0);
+
+if (had_command_timeout) /* set by signal handler */
+ smtp_command_timeout_exit(); /* does not return */
+if (had_command_sigterm)
+ smtp_command_sigterm_exit();
+if (had_data_timeout)
+ smtp_data_timeout_exit();
+if (had_data_sigint)
+ smtp_data_sigint_exit();
+
+/* Timeouts do not get this far. A zero-byte return appears to mean that the
+TLS session has been closed down, not that the socket itself has been closed
+down. Revert to non-TLS handling. */
+
+if (sigalrm_seen)
+ {
+ DEBUG(D_tls) debug_printf("Got tls read timeout\n");
+ state->xfer_error = TRUE;
+ return FALSE;
+ }
-else
- log_write(0, LOG_MAIN, "TLS %s error on connection to %s [%s]: %s%s", when,
- client_host->name, client_host->address,
- (ec == 0)? text : US gnutls_strerror(ec), additional);
-}
+else if (inbytes == 0)
+ {
+ DEBUG(D_tls) debug_printf("Got TLS_EOF\n");
+ tls_close(NULL, TLS_NO_SHUTDOWN);
+ return FALSE;
+ }
+/* Handle genuine errors */
+else if (inbytes < 0)
+ {
+ DEBUG(D_tls) debug_printf("%s: err from gnutls_record_recv\n", __FUNCTION__);
+ record_io_error(state, (int) inbytes, US"recv", NULL);
+ state->xfer_error = TRUE;
+ return FALSE;
+ }
+#ifndef DISABLE_DKIM
+dkim_exim_verify_feed(state->xfer_buffer, inbytes);
+#endif
+state->xfer_buffer_hwm = (int) inbytes;
+state->xfer_buffer_lwm = 0;
+return TRUE;
+}
/*************************************************
* TLS version of getc *
/* This gets the next byte from the TLS input buffer. If the buffer is empty,
it refills the buffer via the GnuTLS reading function.
+Only used by the server-side TLS.
+
+This feeds DKIM and should be used for all message-body reads.
-Arguments: none
+Arguments: lim Maximum amount to read/buffer
Returns: the next character or EOF
*/
int
-tls_getc(void)
+tls_getc(unsigned lim)
{
-if (ssl_xfer_buffer_lwm >= ssl_xfer_buffer_hwm)
- {
- int inbytes;
-
- DEBUG(D_tls) debug_printf("Calling gnutls_record_recv(%lx, %lx, %u)\n",
- (long) tls_session, (long) ssl_xfer_buffer, ssl_xfer_buffer_size);
+exim_gnutls_state_st * state = &state_server;
- if (smtp_receive_timeout > 0) alarm(smtp_receive_timeout);
- inbytes = gnutls_record_recv(tls_session, CS ssl_xfer_buffer,
- ssl_xfer_buffer_size);
- alarm(0);
+if (state->xfer_buffer_lwm >= state->xfer_buffer_hwm)
+ if (!tls_refill(lim))
+ return state->xfer_error ? EOF : smtp_getc(lim);
- /* A zero-byte return appears to mean that the TLS session has been
- closed down, not that the socket itself has been closed down. Revert to
- non-TLS handling. */
-
- if (inbytes == 0)
- {
- DEBUG(D_tls) debug_printf("Got TLS_EOF\n");
-
- receive_getc = smtp_getc;
- receive_ungetc = smtp_ungetc;
- receive_feof = smtp_feof;
- receive_ferror = smtp_ferror;
- receive_smtp_buffered = smtp_buffered;
+/* Something in the buffer; return next uschar */
- gnutls_deinit(tls_session);
- tls_session = NULL;
- tls_active = -1;
- tls_cipher = NULL;
- tls_peerdn = NULL;
+return state->xfer_buffer[state->xfer_buffer_lwm++];
+}
- return smtp_getc();
- }
+BOOL
+tls_hasc(void)
+{
+exim_gnutls_state_st * state = &state_server;
+return state->xfer_buffer_lwm < state->xfer_buffer_hwm;
+}
- /* Handle genuine errors */
+uschar *
+tls_getbuf(unsigned * len)
+{
+exim_gnutls_state_st * state = &state_server;
+unsigned size;
+uschar * buf;
- else if (inbytes < 0)
+if (state->xfer_buffer_lwm >= state->xfer_buffer_hwm)
+ if (!tls_refill(*len))
{
- record_io_error(inbytes, US"recv", NULL);
- ssl_xfer_error = 1;
- return EOF;
+ if (!state->xfer_error) return smtp_getbuf(len);
+ *len = 0;
+ return NULL;
}
- ssl_xfer_buffer_hwm = inbytes;
- ssl_xfer_buffer_lwm = 0;
- }
-
+if ((size = state->xfer_buffer_hwm - state->xfer_buffer_lwm) > *len)
+ size = *len;
+buf = &state->xfer_buffer[state->xfer_buffer_lwm];
+state->xfer_buffer_lwm += size;
+*len = size;
+return buf;
+}
-/* Something in the buffer; return next uschar */
-return ssl_xfer_buffer[ssl_xfer_buffer_lwm++];
+/* Get up to the given number of bytes from any cached data, and feed to dkim. */
+void
+tls_get_cache(unsigned lim)
+{
+#ifndef DISABLE_DKIM
+exim_gnutls_state_st * state = &state_server;
+int n = state->xfer_buffer_hwm - state->xfer_buffer_lwm;
+if (n > lim)
+ n = lim;
+if (n > 0)
+ dkim_exim_verify_feed(state->xfer_buffer+state->xfer_buffer_lwm, n);
+#endif
}
+BOOL
+tls_could_getc(void)
+{
+return state_server.xfer_buffer_lwm < state_server.xfer_buffer_hwm
+ || gnutls_record_check_pending(state_server.session) > 0;
+}
+
/*************************************************
* Read bytes from TLS channel *
*************************************************/
-/*
+/* This does not feed DKIM, so if the caller uses this for reading message body,
+then the caller must feed DKIM.
+
Arguments:
+ ct_ctx client context pointer, or NULL for the one global server context
buff buffer of data
len size of buffer
Returns: the number of bytes read
- -1 after a failed read
+ -1 after a failed read, including EOF
*/
int
-tls_read(uschar *buff, size_t len)
+tls_read(void * ct_ctx, uschar *buff, size_t len)
{
-int inbytes;
+exim_gnutls_state_st * state = ct_ctx ? ct_ctx : &state_server;
+ssize_t inbytes;
+
+if (len > INT_MAX)
+ len = INT_MAX;
+
+if (state->xfer_buffer_lwm < state->xfer_buffer_hwm)
+ DEBUG(D_tls)
+ debug_printf("*** PROBABLY A BUG *** " \
+ "tls_read() called with data in the tls_getc() buffer, %d ignored\n",
+ state->xfer_buffer_hwm - state->xfer_buffer_lwm);
+
+DEBUG(D_tls)
+ debug_printf("Calling gnutls_record_recv(session=%p, buffer=%p, len=" SIZE_T_FMT ")\n",
+ state->session, buff, len);
-DEBUG(D_tls) debug_printf("Calling gnutls_record_recv(%lx, %lx, %u)\n",
- (long) tls_session, (long) buff, len);
+errno = 0;
+do
+ inbytes = gnutls_record_recv(state->session, buff, len);
+while (inbytes == GNUTLS_E_AGAIN);
-inbytes = gnutls_record_recv(tls_session, CS buff, len);
if (inbytes > 0) return inbytes;
if (inbytes == 0)
{
DEBUG(D_tls) debug_printf("Got TLS_EOF\n");
}
-else record_io_error(inbytes, US"recv", NULL);
+else
+ {
+ DEBUG(D_tls) debug_printf("%s: err from gnutls_record_recv\n", __FUNCTION__);
+ record_io_error(state, (int)inbytes, US"recv", NULL);
+ }
return -1;
}
+
/*************************************************
* Write bytes down TLS channel *
*************************************************/
/*
Arguments:
+ ct_ctx client context pointer, or NULL for the one global server context
buff buffer of data
len number of bytes
+ more more data expected soon
+
+Calling with len zero and more unset will flush buffered writes. The buff
+argument can be null for that case.
Returns: the number of bytes after a successful write,
-1 after a failed write
*/
int
-tls_write(const uschar *buff, size_t len)
+tls_write(void * ct_ctx, const uschar * buff, size_t len, BOOL more)
{
-int outbytes;
-int left = len;
+ssize_t outbytes;
+size_t left = len;
+exim_gnutls_state_st * state = ct_ctx ? ct_ctx : &state_server;
+
+#ifdef SUPPORT_CORK
+if (more && !state->corked)
+ {
+ DEBUG(D_tls) debug_printf("gnutls_record_cork(session=%p)\n", state->session);
+ gnutls_record_cork(state->session);
+ state->corked = TRUE;
+ }
+#endif
+
+DEBUG(D_tls) debug_printf("%s(%p, " SIZE_T_FMT "%s)\n", __FUNCTION__,
+ buff, left, more ? ", more" : "");
-DEBUG(D_tls) debug_printf("tls_do_write(%lx, %d)\n", (long) buff, left);
while (left > 0)
{
- DEBUG(D_tls) debug_printf("gnutls_record_send(SSL, %lx, %d)\n", (long)buff,
- left);
- outbytes = gnutls_record_send(tls_session, CS buff, left);
+ DEBUG(D_tls) debug_printf("gnutls_record_send(session=%p, buffer=%p, left=" SIZE_T_FMT ")\n",
+ state->session, buff, left);
+
+ errno = 0;
+ do
+ outbytes = gnutls_record_send(state->session, buff, left);
+ while (outbytes == GNUTLS_E_AGAIN);
+
+ DEBUG(D_tls) debug_printf("outbytes=" SSIZE_T_FMT "\n", outbytes);
- DEBUG(D_tls) debug_printf("outbytes=%d\n", outbytes);
if (outbytes < 0)
{
- record_io_error(outbytes, US"send", NULL);
+#ifdef GNUTLS_E_PREMATURE_TERMINATION
+ if ( outbytes == GNUTLS_E_PREMATURE_TERMINATION && errno == ECONNRESET
+ && !ct_ctx && f.smtp_in_quit
+ )
+ { /* Outlook, dammit */
+ if (LOGGING(protocol_detail))
+ log_write(0, LOG_MAIN, "[%s] after QUIT, client reset TCP before"
+ " SMTP response and TLS close\n", sender_host_address);
+ else
+ DEBUG(D_tls) debug_printf("[%s] SSL_write: after QUIT,"
+ " client reset TCP before TLS close\n", sender_host_address);
+ }
+ else
+#endif
+ {
+ DEBUG(D_tls) debug_printf("%s: gnutls_record_send err\n", __FUNCTION__);
+ record_io_error(state, outbytes, US"send", NULL);
+ }
return -1;
}
if (outbytes == 0)
{
- record_io_error(0, US"send", US"TLS channel closed on write");
+ record_io_error(state, 0, US"send", US"TLS channel closed on write");
return -1;
}
buff += outbytes;
}
-return len;
+if (len > INT_MAX)
+ {
+ DEBUG(D_tls)
+ debug_printf("Whoops! Wrote more bytes (" SIZE_T_FMT ") than INT_MAX\n",
+ len);
+ len = INT_MAX;
+ }
+
+#ifdef SUPPORT_CORK
+if (!more && state->corked)
+ {
+ DEBUG(D_tls) debug_printf("gnutls_record_uncork(session=%p)\n", state->session);
+ do
+ /* We can't use GNUTLS_RECORD_WAIT here, as it retries on
+ GNUTLS_E_AGAIN || GNUTLS_E_INTR, which would break our timeout set by alarm().
+ The GNUTLS_E_AGAIN should not happen ever, as our sockets are blocking anyway.
+ But who knows. (That all relies on the fact that GNUTLS_E_INTR and GNUTLS_E_AGAIN
+ match the EINTR and EAGAIN errno values.) */
+ outbytes = gnutls_record_uncork(state->session, 0);
+ while (outbytes == GNUTLS_E_AGAIN);
+
+ if (outbytes < 0)
+ {
+ record_io_error(state, len, US"uncork", NULL);
+ return -1;
+ }
+
+ state->corked = FALSE;
+ }
+#endif
+
+return (int) len;
}
+
/*************************************************
-* Close down a TLS session *
+* Random number generation *
*************************************************/
-/* This is also called from within a delivery subprocess forked from the
-daemon, to shut down the TLS library, without actually doing a shutdown (which
-would tamper with the TLS session in the parent process).
+/* Pseudo-random number generation. The result is not expected to be
+cryptographically strong but not so weak that someone will shoot themselves
+in the foot using it as a nonce in input in some email header scheme or
+whatever weirdness they'll twist this into. The result should handle fork()
+and avoid repeating sequences. OpenSSL handles that for us.
-Arguments: TRUE if gnutls_bye is to be called
-Returns: nothing
+Arguments:
+ max range maximum
+Returns a random number in range [0, max-1]
*/
-void
-tls_close(BOOL shutdown)
+#ifdef HAVE_GNUTLS_RND
+int
+vaguely_random_number(int max)
+{
+unsigned int r;
+int i, needed_len;
+uschar smallbuf[sizeof(r)];
+
+if (max <= 1)
+ return 0;
+
+needed_len = sizeof(r);
+/* Don't take 8 times more entropy than needed if int is 8 octets and we were
+asked for a number less than 10. */
+
+for (r = max, i = 0; r; ++i)
+ r >>= 1;
+i = (i + 7) / 8;
+if (i < needed_len)
+ needed_len = i;
+
+i = gnutls_rnd(GNUTLS_RND_NONCE, smallbuf, needed_len);
+if (i < 0)
+ {
+ DEBUG(D_all) debug_printf("gnutls_rnd() failed, using fallback\n");
+ return vaguely_random_number_fallback(max);
+ }
+r = 0;
+for (uschar * p = smallbuf; needed_len; --needed_len, ++p)
+ r = r * 256 + *p;
+
+/* We don't particularly care about weighted results; if someone wants
+ * smooth distribution and cares enough then they should submit a patch then. */
+return r % max;
+}
+#else /* HAVE_GNUTLS_RND */
+int
+vaguely_random_number(int max)
{
-if (tls_active < 0) return; /* TLS was not active */
+ return vaguely_random_number_fallback(max);
+}
+#endif /* HAVE_GNUTLS_RND */
-if (shutdown)
+
+
+
+/*************************************************
+* Let tls_require_ciphers be checked at startup *
+*************************************************/
+
+/* The tls_require_ciphers option, if set, must be something which the
+library can parse.
+
+Returns: NULL on success, or error message
+*/
+
+uschar *
+tls_validate_require_cipher(void)
+{
+int rc;
+uschar *expciphers = NULL;
+gnutls_priority_t priority_cache;
+const char *errpos;
+uschar * dummy_errstr;
+
+#ifdef GNUTLS_AUTO_GLOBAL_INIT
+# define validate_check_rc(Label) do { \
+ if (rc != GNUTLS_E_SUCCESS) { if (exim_gnutls_base_init_done) \
+ return string_sprintf("%s failed: %s", (Label), gnutls_strerror(rc)); } } while (0)
+# define return_deinit(Label) do { return (Label); } while (0)
+#else
+# define validate_check_rc(Label) do { \
+ if (rc != GNUTLS_E_SUCCESS) { if (exim_gnutls_base_init_done) gnutls_global_deinit(); \
+ return string_sprintf("%s failed: %s", (Label), gnutls_strerror(rc)); } } while (0)
+# define return_deinit(Label) do { gnutls_global_deinit(); return (Label); } while (0)
+#endif
+
+if (exim_gnutls_base_init_done)
+ log_write(0, LOG_MAIN|LOG_PANIC,
+ "already initialised GnuTLS, Exim developer bug");
+
+#if defined(HAVE_GNUTLS_PKCS11) && !defined(GNUTLS_AUTO_PKCS11_MANUAL)
+if (!gnutls_allow_auto_pkcs11)
{
- DEBUG(D_tls) debug_printf("tls_close(): shutting down TLS\n");
- gnutls_bye(tls_session, GNUTLS_SHUT_WR);
+ rc = gnutls_pkcs11_init(GNUTLS_PKCS11_FLAG_MANUAL, NULL);
+ validate_check_rc(US"gnutls_pkcs11_init");
}
+#endif
+#ifndef GNUTLS_AUTO_GLOBAL_INIT
+rc = gnutls_global_init();
+validate_check_rc(US"gnutls_global_init()");
+#endif
+exim_gnutls_base_init_done = TRUE;
+
+if (!(tls_require_ciphers && *tls_require_ciphers))
+ return_deinit(NULL);
+
+if (!expand_check(tls_require_ciphers, US"tls_require_ciphers", &expciphers,
+ &dummy_errstr))
+ return_deinit(US"failed to expand tls_require_ciphers");
+
+if (!(expciphers && *expciphers))
+ return_deinit(NULL);
-gnutls_deinit(tls_session);
-tls_session = NULL;
+DEBUG(D_tls)
+ debug_printf("tls_require_ciphers expands to \"%s\"\n", expciphers);
+
+rc = gnutls_priority_init(&priority_cache, CS expciphers, &errpos);
+validate_check_rc(string_sprintf(
+ "gnutls_priority_init(%s) failed at offset %ld, \"%.8s..\"",
+ expciphers, (long)(errpos - CS expciphers), errpos));
+
+#undef return_deinit
+#undef validate_check_rc
+#ifndef GNUTLS_AUTO_GLOBAL_INIT
gnutls_global_deinit();
+#endif
+
+return NULL;
+}
+
+
+
-tls_active = -1;
+/*************************************************
+* Report the library versions. *
+*************************************************/
+
+/* See a description in tls-openssl.c for an explanation of why this exists.
+
+Arguments: string to append to
+Returns: string
+*/
+
+gstring *
+tls_version_report(gstring * g)
+{
+return string_fmt_append(g,
+ "Library version: GnuTLS: Compile: %s\n"
+ " Runtime: %s\n",
+ LIBGNUTLS_VERSION,
+ gnutls_check_version(NULL));
}
+#endif /*!MACRO_PREDEF*/
+/* vi: aw ai sw=2
+*/
/* End of tls-gnu.c */
git://git.exim.org / exim.git / blobdiff