* Exim - an Internet mail transport agent *
*************************************************/
-/* Copyright (c) University of Cambridge 1995 - 2009 */
+/* Copyright (c) University of Cambridge 1995 - 2018 */
/* See the file NOTICE for conditions of use and distribution. */
-/* 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.
+/* Copyright (c) Phil Pennock 2012 */
-No cryptographic code is included in Exim. All this module does is to call
-functions from the GnuTLS library. */
+/* 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.
+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.
-/* Heading stuff for GnuTLS */
+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.
+
+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 >= 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 >= 0x030600
+# define GNUTLS_AUTO_DHPARAMS
+#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
+
+#ifdef EXPERIMENTAL_TLS_RESUME
+# if GNUTLS_VERSION_NUMBER < 0x030603
+# error GNUTLS version too early for session-resumption
+# endif
+#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)
+{
+# ifdef EXPERIMENTAL_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
+}
+#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 */
+Changes:
+ gnutls_certificate_verify_peers2(): is new, drop the 2 for old version
+*/
-enum { VERIFY_NONE, VERIFY_OPTIONAL, VERIFY_REQUIRED };
+/* Local static variables for GnuTLS */
-/* Local static variables for GNUTLS */
+/* Values for verify_requirement */
-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;
+ gnutls_certificate_credentials_t x509_cred;
+ gnutls_priority_t priority_cache;
+ 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
-/* Priorities for TLS algorithms to use. In each case there's a default table,
-and space into which it can be copied and altered. */
+ 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
-static const int default_proto_priority[16] = {
- GNUTLS_TLS1,
- GNUTLS_SSL3,
- 0 };
+ tls_support *tlsp; /* set in tls_init() */
-static int proto_priority[16];
+ uschar *xfer_buffer;
+ int xfer_buffer_lwm;
+ int xfer_buffer_hwm;
+} exim_gnutls_state_st;
-static const int default_kx_priority[16] = {
- GNUTLS_KX_RSA,
- GNUTLS_KX_DHE_DSS,
- GNUTLS_KX_DHE_RSA,
- 0 };
+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,
+};
-static int kx_priority[16];
+/* 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 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 exim_gnutls_state_st state_server;
-static int cipher_priority[16];
+#ifndef GNUTLS_AUTO_DHPARAMS
+/* 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_mac_priority[16] = {
- GNUTLS_MAC_SHA,
- GNUTLS_MAC_MD5,
- 0 };
+static gnutls_dh_params_t dh_server_params = NULL;
+#endif
-static int mac_priority[16];
+static int ssl_session_timeout = 7200; /* Two hours */
-/* These two are currently not changeable. */
+static const uschar * const exim_default_gnutls_priority = US"NORMAL";
-static const int comp_priority[16] = { GNUTLS_COMP_NULL, 0 };
-static const int cert_type_priority[16] = { GNUTLS_CRT_X509, 0 };
+/* Guard library core initialisation */
-/* Tables of priority names and equivalent numbers */
+static BOOL exim_gnutls_base_init_done = FALSE;
-typedef struct pri_item {
- uschar *name;
- int *values;
-} pri_item;
+#ifndef DISABLE_OCSP
+static BOOL gnutls_buggy_ocsp = FALSE;
+static BOOL exim_testharness_disable_ocsp_validity_check = FALSE;
+#endif
+#ifdef EXPERIMENTAL_TLS_RESUME
+static gnutls_datum_t server_sessticket_key;
+#endif
-static int tls1_codes[] = { GNUTLS_TLS1, 0 };
-static int ssl3_codes[] = { GNUTLS_SSL3, 0 };
+/* ------------------------------------------------------------------------ */
+/* macros */
-static pri_item proto_index[] = {
- { US"TLS1", tls1_codes },
- { US"SSL3", ssl3_codes }
-};
+#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 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 };
+#ifndef EXIM_CLIENT_DH_MIN_BITS
+# define EXIM_CLIENT_DH_MIN_BITS 1024
+#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 }
-};
+/* 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)
+
+#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 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 }
-};
-static int mac_sha_codes[] = { GNUTLS_MAC_SHA, 0 };
-static int mac_md5_codes[] = { GNUTLS_MAC_MD5, 0 };
-static pri_item mac_index[] = {
- { US"SHA", mac_sha_codes },
- { US"SHA1", mac_sha_codes },
- { US"MD5", mac_md5_codes }
-};
+/* ------------------------------------------------------------------------ */
+/* Callback declarations */
+
+#if EXIM_GNUTLS_LIBRARY_LOG_LEVEL >= 0
+static void exim_gnutls_logger_cb(int level, const char *message);
+#endif
+
+static int exim_sni_handling_cb(gnutls_session_t session);
+
+#ifdef EXPERIMENTAL_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
+/* Daemon one-time initialisation */
+void
+tls_daemon_init(void)
+{
+#ifdef EXPERIMENTAL_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). */
+
+static BOOL once = FALSE;
+if (once) return;
+once = TRUE;
+gnutls_session_ticket_key_generate(&server_sessticket_key); /* >= 2.10.0 */
+if (f.running_in_test_harness) ssl_session_timeout = 6;
+#endif
+}
+
+/* ------------------------------------------------------------------------ */
+/* Static functions */
/*************************************************
* Handle TLS error *
Argument:
prefix text to include in the logged error
- host NULL if setting up a server;
- the connected host if setting up a client
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
+ errstr pointer to returned error string
Returns: OK/DEFER/FAIL
*/
static int
-tls_error(uschar *prefix, host_item *host, const char *msg)
+tls_error(const uschar *prefix, const uschar *msg, const host_item *host,
+ uschar ** errstr)
{
-if (host == NULL)
- {
- uschar *conn_info = smtp_get_connection_info();
- if (strncmp(conn_info, "SMTP ", 5) == 0)
- conn_info += 5;
- log_write(0, LOG_MAIN, "TLS error on %s (%s)%s%s",
- conn_info, prefix, msg ? ": " : "", msg ? msg : "");
- return DEFER;
- }
+if (errstr)
+ *errstr = string_sprintf("(%s)%s%s", prefix, msg ? ": " : "", msg ? msg : US"");
+return host ? FAIL : DEFER;
+}
+
+
+static int
+tls_error_gnu(const uschar *prefix, int err, const host_item *host,
+ uschar ** errstr)
+{
+return tls_error(prefix, US gnutls_strerror(err), host, 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);
+}
+
+
+/*************************************************
+* 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;
+
+if (rc == GNUTLS_E_FATAL_ALERT_RECEIVED)
+ msg = string_sprintf("A TLS fatal alert has been received: %s",
+ US gnutls_alert_get_name(gnutls_alert_get(state->session)));
+else
+ msg = 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
{
- log_write(0, LOG_MAIN, "TLS error on connection to %s [%s] (%s)%s%s",
- host->name, host->address, prefix, msg ? ": " : "", msg ? msg : "");
- return FAIL;
+ 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);
}
}
+
/*************************************************
-* Verify certificate *
+* Set various Exim expansion vars *
*************************************************/
-/* Called after a successful handshake, when certificate verification is
-required or optional, for both server and client.
+#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)]");
+
+return rc;
+}
+
+#undef exim_gnutls_cert_err
-Arguments:
- session GNUTLS session
- error where to put text giving a reason for failure
-Returns: TRUE/FALSE
+/* 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 BOOL
-verify_certificate(gnutls_session session, const char **error)
+static void
+extract_exim_vars_from_tls_state(exim_gnutls_state_st * state)
{
-int verify;
-uschar *dn_string = US"";
-const gnutls_datum *cert;
-unsigned int cert_size = 0;
-
-*error = NULL;
+#ifdef HAVE_GNUTLS_SESSION_CHANNEL_BINDING
+int old_pool;
+int rc;
+gnutls_datum_t channel;
+#endif
+tls_support * tlsp = state->tlsp;
-/* 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. */
+tlsp->active.sock = state->fd_out;
+tlsp->active.tls_ctx = state;
-cert = gnutls_certificate_get_peers(session, &cert_size);
-if (cert != NULL)
- {
- uschar buff[1024];
- gnutls_x509_crt gcert;
+DEBUG(D_tls) debug_printf("cipher: %s\n", state->ciphersuite);
- gnutls_x509_crt_init(&gcert);
- dn_string = US"unknown";
+tlsp->certificate_verified = state->peer_cert_verified;
+#ifdef SUPPORT_DANE
+tlsp->dane_verified = state->peer_dane_verified;
+#endif
- 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);
- }
+/* 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. */
- verify = gnutls_certificate_verify_peers(session);
- }
+tlsp->channelbinding = NULL;
+#ifdef HAVE_GNUTLS_SESSION_CHANNEL_BINDING
+channel.data = NULL;
+channel.size = 0;
+if ((rc = gnutls_session_channel_binding(state->session, GNUTLS_CB_TLS_UNIQUE, &channel)))
+ { DEBUG(D_tls) debug_printf("Channel binding error: %s\n", gnutls_strerror(rc)); }
else
{
- DEBUG(D_tls) debug_printf("no peer certificate supplied\n");
- verify = GNUTLS_CERT_INVALID;
- *error = "not supplied";
+ /* Declare the taintedness of the binding info. On server, untainted; on
+ client, tainted - being the Finish msg from the server. */
+
+ old_pool = store_pool;
+ store_pool = POOL_PERM;
+ tlsp->channelbinding = b64encode_taint(CUS channel.data, (int)channel.size,
+ !!state->host);
+ store_pool = old_pool;
+ DEBUG(D_tls) debug_printf("Have channel bindings cached for possible auth usage\n");
}
+#endif
-/* Handle the result of verification. INVALID seems to be set as well
-as REVOKED, but leave the test for both. */
+/* peercert is set in peer_status() */
+tlsp->peerdn = state->peerdn;
+tlsp->sni = state->received_sni;
-if ((verify & (GNUTLS_CERT_INVALID|GNUTLS_CERT_REVOKED)) != 0)
+/* record our certificate */
{
- tls_certificate_verified = FALSE;
- if (*error == NULL) *error = ((verify & GNUTLS_CERT_REVOKED) != 0)?
- "revoked" : "invalid";
- if (verify_requirement == VERIFY_REQUIRED)
- {
- 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 */
- }
- DEBUG(D_tls) debug_printf("TLS certificate verify failure (%s) overridden "
- "(host in tls_try_verify_hosts): peerdn=%s\n", *error, dn_string);
- }
-else
- {
- 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;
+ }
}
+
+#ifndef GNUTLS_AUTO_DHPARAMS
/*************************************************
* 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 = {.data = NULL, .size = 0};
+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(US"gnutls_dh_params_init", rc, host, errstr);
+
+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(US"gnutls_dh_params_import_pkcs3", rc, host, 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, gnutls_strerror(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, NULL);
+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 not a file", NULL, NULL, errstr);
+ }
+ if (!(fp = fdopen(fd, "rb")))
{
+ saved_errno = errno;
(void)close(fd);
- return tls_error(US"TLS cache stat failed", host, strerror(errno));
+ 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, strerror(errno));
- errno = 0;
- if (read(fd, m.data, m.size) != m.size)
- return tls_error(US"TLS cache read failed", host, strerror(errno));
- (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, gnutls_strerror(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(US"gnutls_dh_params_import_pkcs3", rc, host, 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, NULL);
+ return tls_error(string_open_failed(errno, "\"%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, gnutls_strerror(ret));
+ uschar *temp_fn;
+ unsigned int dh_bits_gen = dh_bits;
- /* Write the parameters to a file in the spool directory so that we
- can use them from other Exim processes. */
+ if ((PATH_MAX - Ustrlen(filename)) < 10)
+ return tls_error(US"Filename too long to generate replacement",
+ filename, NULL, errstr);
- 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, NULL);
- (void)fchown(fd, exim_uid, exim_gid); /* Probably not necessary */
+ temp_fn = string_copy(US"%s.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 */
- /* 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
- */
+ /* 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. */
- m.size = PARAM_SIZE;
- m.data = malloc(m.size);
- if (m.data == NULL)
- return tls_error(US"memory allocation failed", host, strerror(errno));
+ 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;
- 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, gnutls_strerror(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(US"gnutls_dh_params_generate2", rc, host, 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(US"gnutls_dh_params_export_pkcs3(NULL) sizing",
+ rc, host, 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(US"gnutls_dh_params_export_pkcs3() real", rc, host, errstr);
+ }
+ m.size = sz; /* shrink by 1, probably */
- m.size = Ustrlen(m.data);
- errno = 0;
- if (write(fd, m.data, m.size) != m.size || write(fd, "\n", 1) != 1)
- return tls_error(US"TLS cache write failed", host, strerror(errno));
+ 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",
- tempfilename, filename), host, strerror(errno));
+ 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;
}
+#endif
-/*************************************************
-* 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;
-client_host = host;
+where = US"initialising pkey";
+if ((rc = gnutls_x509_privkey_init(&pkey))) goto err;
-rc = gnutls_global_init();
-if (rc < 0) return tls_error(US"tls-init", host, gnutls_strerror(rc));
+where = US"initialising cert";
+if ((rc = gnutls_x509_crt_init(&cert))) goto err;
-/* Create D-H parameters, or read them from the cache file. This function does
-its own SMTP error messaging. */
+where = US"generating pkey";
+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, now + 60 * 60)) /* 1 hr */
+ || (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->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(where, rc, NULL, errstr);
+ goto out;
+}
-rc = init_dh(host);
-if (rc != OK) return rc;
-/* Create the credentials structure */
-rc = gnutls_certificate_allocate_credentials(&x509_cred);
-if (rc < 0)
- return tls_error(US"certificate_allocate_credentials",
- host, gnutls_strerror(rc));
-/* This stuff must be done for each session, because different certificates
-may be required for different sessions. */
+/* Add certificate and key, from files.
-if (!expand_check(certificate, US"tls_certificate", &cert_expanded))
- return DEFER;
+Return:
+ Zero or negative: good. Negate value for certificate index if < 0.
+ Greater than zero: FAIL or DEFER code.
+*/
-key_expanded = NULL;
-if (privatekey != NULL)
- {
- if (!expand_check(privatekey, US"tls_privatekey", &key_expanded))
- return DEFER;
- }
+static int
+tls_add_certfile(exim_gnutls_state_st * state, const host_item * host,
+ uschar * certfile, uschar * keyfile, uschar ** errstr)
+{
+int rc = gnutls_certificate_set_x509_key_file(state->x509_cred,
+ CS certfile, CS keyfile, GNUTLS_X509_FMT_PEM);
+if (rc < 0)
+ return tls_error_gnu(
+ string_sprintf("cert/key setup: cert=%s key=%s", certfile, keyfile),
+ rc, host, errstr);
+return -rc;
+}
-/* 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;
+#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. */
-/* Set the certificate and private keys */
+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);
-if (cert_expanded != NULL)
+if ((ret = gnutls_load_file(ptr, ocsp_response)) < 0)
{
- 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, gnutls_strerror(rc));
- }
+ 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;
}
-/* A certificate is mandatory in a server, but not in a client */
+tls_in.ocsp = OCSP_VFY_NOT_TRIED;
+return 0;
+}
+#endif
+
-else
+#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 unsigned char *data, unsigned size)
+{
+/* https://www.iana.org/assignments/tls-extensiontype-values/tls-extensiontype-values.xhtml */
+if (tls_id == 5) /* status_request */
{
- if (host == NULL)
- return tls_error(US"no TLS server certificate is specified", NULL, NULL);
- DEBUG(D_tls) debug_printf("no TLS client certificate is specified\n");
+ DEBUG(D_tls) debug_printf("Seen status_request extension from client\n");
+ tls_in.ocsp = OCSP_NOT_RESP;
}
+return 0;
+}
-/* 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 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 */
+return gnutls_ext_raw_parse(NULL, tls_server_clienthello_ext, msg,
+ GNUTLS_EXT_RAW_FLAG_TLS_CLIENT_HELLO);
+}
-if (cas != NULL)
- {
- struct stat statbuf;
- if (!expand_check(cas, US"tls_verify_certificates", &cas_expanded))
- return DEFER;
+/* 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 */
+ {
+ 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;
+}
- if (stat(CS cas_expanded, &statbuf) < 0)
- {
- log_write(0, LOG_MAIN|LOG_PANIC, "could not stat %s "
- "(tls_verify_certificates): %s", cas_expanded, strerror(errno));
- return DEFER;
- }
+/* 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
+/*XXX crashes */
+return gnutls_ext_raw_parse(NULL, tls_server_servercerts_ext, msg, 0);
+#endif
+}
+#endif
- DEBUG(D_tls) debug_printf("verify certificates = %s size=" OFF_T_FMT "\n",
- cas_expanded, statbuf.st_size);
+/*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)
- /* If the cert file is empty, there's no point in loading the CRL file. */
+This is different to tls1.2 - where it is a separate record (wireshake term) / handshake message (gnutls term).
+*/
- 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, gnutls_strerror(rc));
+#if defined(EXPERIMENTAL_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 (crl != NULL && *crl != 0)
- {
- 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, gnutls_strerror(rc));
- }
- }
+/* 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)
+ {
+# 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 EXPERIMENTAL_TLS_RESUME
+ case GNUTLS_HANDSHAKE_NEW_SESSION_TICKET:
+ return tls_server_ticket_cb(sess, htype, when, incoming, msg);
+# endif
+ default:
+ return 0;
}
-
-/* Associate the parameters with the x509 credentials structure. */
-
-gnutls_certificate_set_dh_params(x509_cred, dh_params);
-
-DEBUG(D_tls) debug_printf("initialized certificate stuff\n");
-return OK;
}
+#endif
-
+#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)
+ {
+ DEBUG(D_tls) debug_printf("Permitting known bad OCSP response\n");
+ exim_testharness_disable_ocsp_validity_check = TRUE;
+ }
+}
+#endif
/*************************************************
-* Remove from a priority list *
+* Variables re-expanded post-SNI *
*************************************************/
-/* Cautiously written so that it will remove duplicates if present.
+/* 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
- remove_list a zero-terminated list to be removed
+ state exim_gnutls_state_st *
+ errstr error string pointer
-Returns: nothing
+Returns: OK/DEFER/FAIL
*/
-static void
-remove_priority(int *list, int *remove_list)
+static int
+tls_expand_session_files(exim_gnutls_state_st * state, uschar ** errstr)
{
-for (; *remove_list != 0; remove_list++)
- {
- int *p = list;
- while (*p != 0)
+struct stat statbuf;
+int rc;
+const host_item *host = state->host; /* macro should be reconsidered? */
+uschar *saved_tls_certificate = NULL;
+uschar *saved_tls_privatekey = NULL;
+uschar *saved_tls_verify_certificates = NULL;
+uschar *saved_tls_crl = NULL;
+int cert_count;
+
+/* We check for tls_sni *before* expansion. */
+if (!host) /* server */
+ if (!state->received_sni)
{
- if (*p == *remove_list)
+ 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")
+ ) )
{
- int *pp = p;
- do { pp[0] = pp[1]; pp++; } while (*pp != 0);
+ DEBUG(D_tls) debug_printf("We will re-expand TLS session files if we receive SNI.\n");
+ state->trigger_sni_changes = TRUE;
}
- else p++;
}
+ else
+ {
+ /* 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 ((rc = gnutls_certificate_allocate_credentials(&state->x509_cred)))
+ return tls_error_gnu(US"gnutls_certificate_allocate_credentials",
+ rc, host, errstr);
+
+#ifdef SUPPORT_SRV_OCSP_STACK
+gnutls_certificate_set_flags(state->x509_cred, GNUTLS_CERTIFICATE_API_V2);
+
+# if !defined(DISABLE_OCSP) && defined(SUPPORT_GNUTLS_EXT_RAW_PARSE)
+if (!host && 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(state->x509_cred,
+ GNUTLS_CERTIFICATE_API_V2 | GNUTLS_CERTIFICATE_SKIP_OCSP_RESPONSE_CHECK);
}
-}
+# endif
+#endif
+/* 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. */
+/* check if we at least have a certificate, before doing expensive
+D-H generation. */
-/*************************************************
-* Add to a priority list *
-*************************************************/
+if (!expand_check_tlsvar(tls_certificate, errstr))
+ return DEFER;
-/* Cautiously written to check the list size
+/* certificate is mandatory in server, optional in client */
-Arguments:
- list a zero-terminated list
- list_max maximum offset in the list
- add_list a zero-terminated list to be added
+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");
-Returns: TRUE if OK; FALSE if list overflows
-*/
+if (state->tls_privatekey && !expand_check_tlsvar(tls_privatekey, errstr))
+ return DEFER;
-static BOOL
-add_priority(int *list, int list_max, int *add_list)
-{
-int next = 0;
-while (list[next] != 0) next++;
-while (*add_list != 0)
+/* tls_privatekey is optional, defaulting to same file as certificate */
+
+if (!state->tls_privatekey || !*state->tls_privatekey)
{
- if (next >= list_max) return FALSE;
- list[next++] = *add_list++;
+ state->tls_privatekey = state->tls_certificate;
+ state->exp_tls_privatekey = state->exp_tls_certificate;
}
-list[next] = 0;
-return TRUE;
-}
+if (state->exp_tls_certificate && *state->exp_tls_certificate)
+ {
+ DEBUG(D_tls) debug_printf("certificate file = %s\nkey file = %s\n",
+ state->exp_tls_certificate, state->exp_tls_privatekey);
-/*************************************************
-* Adjust a priority list *
-*************************************************/
+ 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");
+ }
+ else
+ {
+ DEBUG(D_tls) debug_printf("TLS SNI: have a changed cert/key pair.\n");
+ }
-/* This function is called to adjust the lists of cipher algorithms, MAC
-algorithms, key-exchange methods, and protocols.
+ if (!host) /* server */
+ {
+ const uschar * clist = state->exp_tls_certificate;
+ const uschar * klist = state->exp_tls_privatekey;
+ const uschar * olist;
+ int csep = 0, ksep = 0, osep = 0, cnt = 0;
+ 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(tls_ocsp_file, US"tls_ocsp_file", &ofile, errstr))
+ return DEFER;
+ olist = ofile;
+#endif
-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
+ 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, host, errstr);
+ else if (0 < (rc = tls_add_certfile(state, host, cfile, kfile, errstr)))
+ return rc;
+ else
+ {
+ int gnutls_cert_index = -rc;
+ DEBUG(D_tls) debug_printf("TLS: cert/key %d %s registered\n",
+ gnutls_cert_index, cfile);
+
+#ifndef DISABLE_OCSP
+ if (tls_ocsp_file)
+ {
+ /* 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->x509_cred, CCS ofile, gnutls_cert_index,
+ ocsp_fmt)) < 0)
+ return tls_error_gnu(
+ US"gnutls_certificate_set_ocsp_status_request_file2",
+ rc, host, errstr);
+ DEBUG(D_tls)
+ debug_printf(" %d response%s loaded\n", rc, rc>1 ? "s":"");
+
+ /* Arrange callbacks for OCSP request observability */
+
+ gnutls_handshake_set_hook_function(state->session,
+ GNUTLS_HANDSHAKE_ANY, GNUTLS_HOOK_POST, tls_server_hook_cb);
+
+# else
+# if defined(SUPPORT_SRV_OCSP_STACK)
+ if ((rc = gnutls_certificate_set_ocsp_status_request_function2(
+ state->x509_cred, gnutls_cert_index,
+ server_ocsp_stapling_cb, ofile)))
+ return tls_error_gnu(
+ US"gnutls_certificate_set_ocsp_status_request_function2",
+ rc, host, 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->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 */
+ }
+ }
+ else /* client */
+ {
+ if (0 < (rc = tls_add_certfile(state, host,
+ state->exp_tls_certificate, state->exp_tls_privatekey, errstr)))
+ return rc;
+ DEBUG(D_tls) debug_printf("TLS: cert/key registered\n");
+ }
+ } /* tls_certificate */
- which text for an error message
-Returns: FALSE if the table overflows, else TRUE
-*/
+/* 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. */
-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->tls_verify_certificates && *state->tls_verify_certificates)
+ {
+ 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))
+ {
+ 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;
+ }
-while ((t = string_nextinlist(&s, &sep, big_buffer, big_buffer_size)) != NULL)
+#ifdef SUPPORT_SYSDEFAULT_CABUNDLE
+if (Ustrcmp(state->exp_tls_verify_certificates, "system") == 0)
+ cert_count = gnutls_certificate_set_x509_system_trust(state->x509_cred);
+else
+#endif
{
- int i;
- BOOL exclude = t[0] == '!';
- if (first && !exclude) plist[0] = 0;
- first = FALSE;
- for (i = 0; i < isize; i++)
+ if (Ustat(state->exp_tls_verify_certificates, &statbuf) < 0)
{
- uschar *ss = strstric(t, index[i].name, FALSE);
- if (ss != NULL)
- {
- 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;
- }
- }
- }
- }
+ log_write(0, LOG_MAIN|LOG_PANIC, "could not stat '%s' "
+ "(tls_verify_certificates): %s", state->exp_tls_verify_certificates,
+ 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))
+ {
+ DEBUG(D_tls)
+ debug_printf("verify certificates path is a dir: \"%s\"\n",
+ state->exp_tls_verify_certificates);
+ log_write(0, LOG_MAIN|LOG_PANIC,
+ "tls_verify_certificates \"%s\" is a directory",
+ state->exp_tls_verify_certificates);
+ return DEFER;
+ }
+#endif
+
+ DEBUG(D_tls) debug_printf("verify certificates = %s size=" OFF_T_FMT "\n",
+ state->exp_tls_verify_certificates, 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->x509_cred,
+ CS state->exp_tls_verify_certificates, GNUTLS_X509_FMT_PEM)
+ :
+#endif
+ gnutls_certificate_set_x509_trust_file(state->x509_cred,
+ CS state->exp_tls_verify_certificates, 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)
+ gnutls_certificate_send_x509_rdn_sequence(state->session, 1);
+#endif
}
+if (cert_count < 0)
+ return tls_error_gnu(US"setting certificate trust", cert_count, host, errstr);
DEBUG(D_tls)
+ debug_printf("Added %d certificate authorities.\n", cert_count);
+
+if (state->tls_crl && *state->tls_crl &&
+ state->exp_tls_crl && *state->exp_tls_crl)
{
- int *ptr = plist;
- debug_printf("adjusted %s priorities:", which);
- while (*ptr != 0) debug_printf(" %d", *ptr++);
- debug_printf("\n");
+ DEBUG(D_tls) debug_printf("loading CRL file = %s\n", state->exp_tls_crl);
+ if ((cert_count = gnutls_certificate_set_x509_crl_file(state->x509_cred,
+ CS state->exp_tls_crl, GNUTLS_X509_FMT_PEM)) < 0)
+ return tls_error_gnu(US"gnutls_certificate_set_x509_crl_file",
+ cert_count, host, errstr);
+
+ DEBUG(D_tls) debug_printf("Processed %d CRLs.\n", cert_count);
}
-return TRUE;
+return OK;
}
/*************************************************
-* Initialize a single GNUTLS session *
+* Set X.509 state variables *
+*************************************************/
+
+/* 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? */
+
+#ifndef GNUTLS_AUTO_DHPARAMS
+/* 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 */
+ gnutls_certificate_set_dh_params(state->x509_cred, dh_server_params);
+ }
+#endif
+
+/* Link the credentials to the session. */
+
+if ((rc = gnutls_credentials_set(state->session,
+ GNUTLS_CRD_CERTIFICATE, state->x509_cred)))
+ return tls_error_gnu(US"gnutls_credentials_set", rc, host, errstr);
+
+return OK;
+}
+
+/*************************************************
+* Initialize for GnuTLS *
*************************************************/
-/* Set the algorithm, the db backend, whether to request certificates etc.
-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.
+#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)
+ {
+ 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
+
-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
+ certificate certificate file
+ privatekey private key file
+ sni TLS SNI to send, sometimes when client; else NULL
+ cas CA certs file
+ crl CRL file
+ 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,
+ const uschar *certificate,
+ const uschar *privatekey,
+ const uschar *sni,
+ const uschar *cas,
+ const uschar *crl,
+ 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;
+const char * errpos;
+const uschar * p;
-gnutls_init(&session, side);
+if (!exim_gnutls_base_init_done)
+ {
+ 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(US"gnutls_pkcs11_init", rc, host, errstr);
+#endif
+
+#ifndef GNUTLS_AUTO_GLOBAL_INIT
+ if ((rc = gnutls_global_init()))
+ return tls_error_gnu(US"gnutls_global_init", rc, host, errstr);
+#endif
-/* Initialize the lists of permitted protocols, key-exchange methods, ciphers,
-and MACs. */
+#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
-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));
+#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
-/* 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. */
+ exim_gnutls_base_init_done = TRUE;
+ }
-if (expciphers != NULL)
+if (host)
{
- uschar *s = expciphers;
- while (*s != 0) { if (*s == '-') *s = '_'; s++; }
+ /* 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), FALSE);
+ store_pool = old_pool;
+
+ memcpy(state, &exim_gnutls_state_init, sizeof(exim_gnutls_state_init));
+ state->tlsp = tlsp;
+ DEBUG(D_tls) debug_printf("initialising GnuTLS client session\n");
+ rc = gnutls_init(&state->session, GNUTLS_CLIENT);
}
-
-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")))
+else
{
- gnutls_deinit(session);
- return NULL;
+ state = &state_server;
+ memcpy(state, &exim_gnutls_state_init, sizeof(exim_gnutls_state_init));
+ state->tlsp = tlsp;
+ DEBUG(D_tls) debug_printf("initialising GnuTLS server session\n");
+ rc = gnutls_init(&state->session, GNUTLS_SERVER);
}
+if (rc)
+ return tls_error_gnu(US"gnutls_init", rc, host, errstr);
-/* Define the various priorities */
+state->host = host;
-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);
+state->tls_certificate = certificate;
+state->tls_privatekey = privatekey;
+state->tls_require_ciphers = require_ciphers;
+state->tls_sni = sni;
+state->tls_verify_certificates = cas;
+state->tls_crl = crl;
-gnutls_cred_set(session, GNUTLS_CRD_CERTIFICATE, x509_cred);
+/* This handles the variables that might get re-expanded after TLS SNI;
+that's tls_certificate, tls_privatekey, tls_verify_certificates, tls_crl */
+
+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. */
+
+if ((rc = tls_set_remaining_x509(state, errstr)) != OK) return rc;
+
+/* set SNI in client, only */
+if (host)
+ {
+ if (!expand_check(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(US"gnutls_server_name_set", rc, host, 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);
+
+/* 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. */
+
+p = NULL;
+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);
+ }
+ }
+if (!p)
+ {
+ p = exim_default_gnutls_priority;
+ DEBUG(D_tls)
+ debug_printf("GnuTLS using default session cipher/priority \"%s\"\n", p);
+ }
-gnutls_dh_set_prime_bits(session, DH_BITS);
+if ((rc = gnutls_priority_init(&state->priority_cache, CCS p, &errpos)))
+ return tls_error_gnu(string_sprintf(
+ "gnutls_priority_init(%s) failed at offset %ld, \"%.6s..\"",
+ p, errpos - CS p, errpos),
+ rc, host, errstr);
-/* Request or demand a certificate of the peer, as configured. This will
-happen only in a server. */
+if ((rc = gnutls_priority_set(state->session, state->priority_cache)))
+ return tls_error_gnu(US"gnutls_priority_set", rc, host, errstr);
-if (verify_requirement != VERIFY_NONE)
- gnutls_certificate_server_set_request(session,
- (verify_requirement == VERIFY_OPTIONAL)?
- GNUTLS_CERT_REQUEST : GNUTLS_CERT_REQUIRE);
+/* This also sets the server ticket expiration time to the same, and
+the STEK rotation time to 3x. */
-gnutls_db_set_cache_expiration(session, ssl_session_timeout);
+gnutls_db_set_cache_expiration(state->session, ssl_session_timeout);
/* Reduce security in favour of increased compatibility, if the admin
decides to make that trade-off. */
{
#if LIBGNUTLS_VERSION_NUMBER >= 0x020104
DEBUG(D_tls) debug_printf("lowering GnuTLS security, compatibility mode\n");
- gnutls_session_enable_compatibility_mode(session);
+ 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;
+}
+
+
+
+/*************************************************
+* Extract peer information *
+*************************************************/
+
+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
+
+Returns: OK/DEFER/FAIL
+*/
+
+static int
+peer_status(exim_gnutls_state_st * state, uschar ** errstr)
+{
+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);
+
+old_pool = store_pool;
+ {
+ tls_support * tlsp = state->tlsp;
+ store_pool = POOL_PERM;
+
+#ifdef SUPPORT_GNUTLS_SESS_DESC
+ {
+ gstring * g = NULL;
+ uschar * s = US gnutls_session_get_desc(session), c;
+
+ /* Nikos M suggests we use this by preference. It returns like:
+ (TLS1.3)-(ECDHE-SECP256R1)-(RSA-PSS-RSAE-SHA256)-(AES-256-GCM)
+
+ For partial back-compat, put a colon after the TLS version, replace the
+ )-( grouping with __, replace in-group - with _ and append the :keysize. */
+
+ /* 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 */
+
+ 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);
+
+ /* 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. */
+
+ for (uschar * p = state->ciphersuite; *p; p++) if (isspace(*p)) *p = '-';
+ tlsp->ver = string_copyn(state->ciphersuite,
+ Ustrchr(state->ciphersuite, ':') - state->ciphersuite);
+#endif
+
+/* debug_printf("peer_status: ciphersuite %s\n", state->ciphersuite); */
+
+ 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((Label), rc, state->host, 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, TRUE); /* 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
}
+
/*************************************************
-* Get name of cipher in use *
+* Verify peer certificate *
*************************************************/
-/* The answer is left in a static buffer, and tls_cipher is set to point
-to it.
+/* 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
-Argument: pointer to a GnuTLS session
-Returns: nothing
+Returns:
+ FALSE if the session should be rejected
+ TRUE if the cert is okay or we just don't care
*/
-static void
-construct_cipher_name(gnutls_session session)
+static BOOL
+verify_certificate(exim_gnutls_state_st * state, uschar ** errstr)
{
-static uschar cipherbuf[256];
-uschar *ver;
-int bits, c, kx, mac;
+int rc;
+uint verify;
+
+DEBUG(D_tls) debug_printf("TLS: checking peer certificate\n");
+*errstr = NULL;
+rc = peer_status(state, errstr);
-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 */
+if (state->verify_requirement == VERIFY_NONE)
+ return TRUE;
-c = gnutls_cipher_get(session);
-bits = gnutls_cipher_get_key_size(c);
+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 *), FALSE);
+ ddl = store_get(nrec * sizeof(int), FALSE);
+ 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, TRUE);
+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))))
+ {
+ 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 writable by uid exim\n"
+ " add SSLKEYLOGFILE to keep_environment in the exim config\n"
+ " run 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)"
+ " Trying to use add_environment for this will not work\n");
+#endif
+}
+
+
+#ifdef EXPERIMENTAL_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
+/* ------------------------------------------------------------------------ */
+/* 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:
+ require_ciphers list of allowed ciphers or NULL
+ 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(const uschar * require_ciphers, 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, tls_certificate, tls_privatekey,
+ NULL, tls_verify_certificates, tls_crl,
+ require_ciphers, &state, &tls_in, errstr)) != OK) return rc;
+
+#ifdef MEASURE_TIMING
+ report_time_since(&t0, US"server tls_init (delta)");
+#endif
+ }
+
+#ifdef EXPERIMENTAL_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->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)
+ {
+ /* 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);
+ gnutls_db_remove_session(state->session);
+ }
+ else
+ {
+ tls_error_gnu(US"gnutls_handshake", rc, NULL, errstr);
+ (void) gnutls_alert_send_appropriate(state->session, rc);
+ gnutls_deinit(state->session);
+ gnutls_certificate_free_credentials(state->x509_cred);
+ 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 EXPERIMENTAL_TLS_RESUME
+tls_server_resume_posthandshake(state);
+#endif
+
+DEBUG(D_tls) post_handshake_debug(state);
+
+/* 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_ungetc = tls_ungetc;
+receive_feof = tls_feof;
+receive_ferror = tls_ferror;
+receive_smtp_buffered = tls_smtp_buffered;
+
+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->name, NULL);
+#else
+ host->name;
+#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 *), FALSE);
+dane_data_len = store_get(i * sizeof(int), FALSE);
+
+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 EXPERIMENTAL_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,
+ host_item * host, smtp_transport_options_block * ob)
+{
+tlsp->resumption = RESUME_SUPPORTED;
+if (verify_check_given_host(CUSS &ob->tls_resumption_hosts, host) == OK)
+ {
+ dbdata_tls_session * dt;
+ int len, rc;
+ open_db dbblock, * dbm_file;
+
+ DEBUG(D_tls)
+ debug_printf("check for resumable session for %s\n", host->address);
+ tlsp->host_resumable = TRUE;
+ tlsp->resumption |= RESUME_CLIENT_REQUESTED;
+ if ((dbm_file = dbfn_open(US"tls", O_RDONLY, &dbblock, FALSE, FALSE)))
+ {
+ /* Key for the db is the IP. 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, host->address, &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, TRUE);
+
+ 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_delete(dbm_file, host->address);
+ dbfn_write(dbm_file, host->address, 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, host_item * host,
+ 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);
-mac = gnutls_mac_get(session);
-kx = gnutls_kx_get(session);
+tls_retrieve_session(tlsp, state->session, host, ob);
+}
-string_format(cipherbuf, sizeof(cipherbuf), "%s:%s:%u", ver,
- gnutls_cipher_suite_get_name(kx, c, mac), bits);
-tls_cipher = cipherbuf;
+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;
+ }
-DEBUG(D_tls) debug_printf("cipher: %s\n", cipherbuf);
+tls_save_session(tlsp, state->session, host);
}
-
+#endif /* EXPERIMENTAL_TLS_RESUME */
/*************************************************
-* Start a TLS session in a server *
+* Start a TLS session in a client *
*************************************************/
-/* 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.
+/* Called from the smtp transport after STARTTLS has been accepted.
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
-
-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.
+ 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
*/
-int
-tls_server_start(uschar *require_ciphers, uschar *require_mac,
- uschar *require_kx, uschar *require_proto)
+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;
-const char *error;
-uschar *expciphers = NULL;
-uschar *expmac = NULL;
-uschar *expkx = NULL;
-uschar *expproto = NULL;
+exim_gnutls_state_st * state = NULL;
+uschar * cipher_list = NULL;
+
+#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
-/* Check for previous activation */
+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 */
+
+if (conn_args->dane && ob->dane_require_tls_ciphers)
{
- tls_error("STARTTLS received after TLS started", NULL, "");
- 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->tls_certificate, ob->tls_privatekey,
+ ob->tls_sni, ob->tls_verify_certificates, ob->tls_crl,
+ 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. */
+ {
+ 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;
+ }
-tls_certificate_verified = FALSE;
-verify_requirement = VERIFY_NONE;
+ 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);
+ }
-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;
+/* 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 */
-/* Prepare for new connection */
+#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);
+ }
-tls_session = tls_session_init(GNUTLS_SERVER, expciphers, expmac, expkx,
- expproto);
-if (tls_session == NULL)
- return tls_error(US"tls_session_init", NULL,
- gnutls_strerror(GNUTLS_E_MEMORY_ERROR));
+#ifndef DISABLE_OCSP
+ /* supported since GnuTLS 3.1.3 */
+if (request_ocsp)
+ {
+ 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(US"cert-status-req", rc, state->host, errstr);
+ return FALSE;
+ }
+ tlsp->ocsp = OCSP_NOT_RESP;
+ }
+#endif
-/* 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 EXPERIMENTAL_TLS_RESUME
+tls_client_resume_prehandshake(state, tlsp, host, ob);
+#endif
-if (!tls_on_connect)
+#ifndef DISABLE_EVENT
+if (tb && tb->event_action)
{
- smtp_printf("220 TLS go ahead\r\n");
- fflush(smtp_out);
+ state->event_action = tb->event_action;
+ gnutls_session_set_ptr(state->session, state);
+ gnutls_certificate_set_verify_function(state->x509_cred, verify_cb);
}
+#endif
-/* Now negotiate the TLS session. We put our own timer on it, since it seems
-that the GnuTLS library doesn't. */
+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)
{
- tls_error(US"gnutls_handshake", NULL,
- sigalrm_seen ? "timed out" : 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)
+ if (sigalrm_seen)
{
- (void)fclose(smtp_out);
- (void)fclose(smtp_in);
+ gnutls_alert_send(state->session, GNUTLS_AL_FATAL, GNUTLS_A_USER_CANCELED);
+ tls_error(US"gnutls_handshake", US"timed out", state->host, errstr);
}
-
- return FAIL;
+ else
+ tls_error_gnu(US"gnutls_handshake", rc, state->host, errstr);
+ return FALSE;
}
-DEBUG(D_tls) debug_printf("gnutls_handshake was successful\n");
+DEBUG(D_tls) post_handshake_debug(state);
-if (verify_requirement != VERIFY_NONE &&
- !verify_certificate(tls_session, &error))
+/* Verify late */
+
+if (!verify_certificate(state, errstr))
{
- tls_error(US"certificate verification failed", NULL, error);
- return FAIL;
+ tls_error(US"certificate verification failed", *errstr, state->host, errstr);
+ return FALSE;
}
-construct_cipher_name(tls_session);
+#ifdef GNUTLS_SFLAGS_EXT_MASTER_SECRET
+if (gnutls_session_get_flags(state->session) & GNUTLS_SFLAGS_EXT_MASTER_SECRET)
+ tlsp->ext_master_secret = TRUE;
+#endif
-/* TLS has been set up. Adjust the input functions to read via TLS,
-and initialize appropriately. */
+#ifndef DISABLE_OCSP
+if (request_ocsp)
+ {
+ 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(US"ocsp decode", rc, state->host, errstr);
+ if (idx == 0 && rc)
+ (void) tls_error_gnu(US"ocsp decode", rc, state->host, 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
-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;
+#ifdef EXPERIMENTAL_TLS_RESUME
+tls_client_resume_posthandshake(state, tlsp, host);
+#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 *
+* Close down a TLS session *
*************************************************/
-/* Called from the smtp transport after STARTTLS has been accepted.
+/* 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).
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 context pointer, or NULL for the one global server context
+ shutdown 1 if TLS close-alert is to be sent,
+ 2 if also response to be waited for
+
+Returns: nothing
*/
-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_close(void * ct_ctx, int shutdown)
{
-const gnutls_datum *server_certs;
-uschar *expciphers = NULL;
-uschar *expmac = NULL;
-uschar *expkx = NULL;
-uschar *expproto = NULL;
-const char *error;
-unsigned int server_certs_size;
-int rc;
-
-DEBUG(D_tls) debug_printf("initializing GnuTLS as a client\n");
-
-verify_requirement = (verify_certs == NULL)? VERIFY_NONE : VERIFY_REQUIRED;
-rc = tls_init(host, certificate, privatekey, verify_certs, verify_crl);
-if (rc != OK) return rc;
+exim_gnutls_state_st * state = ct_ctx ? ct_ctx : &state_server;
+tls_support * tlsp = state->tlsp;
-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;
-
-tls_session = tls_session_init(GNUTLS_CLIENT, expciphers, expmac, expkx,
- expproto);
+if (!tlsp || tlsp->active.sock < 0) return; /* TLS was not active */
-if (tls_session == NULL)
- return tls_error(US "tls_session_init", host,
- gnutls_strerror(GNUTLS_E_MEMORY_ERROR));
+if (shutdown)
+ {
+ DEBUG(D_tls) debug_printf("tls_close(): shutting down TLS%s\n",
+ shutdown > 1 ? " (with response-wait)" : "");
-gnutls_transport_set_ptr(tls_session, (gnutls_transport_ptr)fd);
+ ALARM(2);
+ gnutls_bye(state->session, shutdown > 1 ? GNUTLS_SHUT_RDWR : GNUTLS_SHUT_WR);
+ ALARM_CLR(0);
+ }
-/* There doesn't seem to be a built-in timeout on connection. */
+if (!ct_ctx) /* server */
+ {
+ receive_getc = smtp_getc;
+ receive_getbuf = smtp_getbuf;
+ receive_get_cache = smtp_get_cache;
+ receive_ungetc = smtp_ungetc;
+ receive_feof = smtp_feof;
+ receive_ferror = smtp_ferror;
+ receive_smtp_buffered = smtp_buffered;
+ }
-sigalrm_seen = FALSE;
-alarm(timeout);
-rc = gnutls_handshake(tls_session);
-alarm(0);
+gnutls_deinit(state->session);
+gnutls_certificate_free_credentials(state->x509_cred);
-if (rc < 0)
- return tls_error(US "gnutls_handshake", host,
- sigalrm_seen ? "timed out" : gnutls_strerror(rc));
+tlsp->active.sock = -1;
+tlsp->active.tls_ctx = NULL;
+/* Leave bits, peercert, cipher, peerdn, certificate_verified set, for logging */
+tlsp->channelbinding = NULL;
-server_certs = gnutls_certificate_get_peers(tls_session, &server_certs_size);
-if (server_certs != NULL)
- {
- uschar buff[1024];
- gnutls_x509_crt gcert;
+if (state->xfer_buffer) store_free(state->xfer_buffer);
+memcpy(state, &exim_gnutls_state_init, sizeof(exim_gnutls_state_init));
+}
- gnutls_x509_crt_init(&gcert);
- tls_peerdn = US"unknown";
- 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);
- }
- }
-/* Should we also verify the hostname here? */
-if (verify_requirement != VERIFY_NONE &&
- !verify_certificate(tls_session, &error))
- return tls_error(US"certificate verification failed", host, error);
+static BOOL
+tls_refill(unsigned lim)
+{
+exim_gnutls_state_st * state = &state_server;
+ssize_t inbytes;
-construct_cipher_name(tls_session); /* Sets tls_cipher */
-tls_active = fd;
-return OK;
-}
+DEBUG(D_tls) debug_printf("Calling gnutls_record_recv(%p, %p, %u)\n",
+ state->session, state->xfer_buffer, ssl_xfer_buffer_size);
+sigalrm_seen = FALSE;
+if (smtp_receive_timeout > 0) ALARM(smtp_receive_timeout);
+do
+ inbytes = gnutls_record_recv(state->session, state->xfer_buffer,
+ MIN(ssl_xfer_buffer_size, lim));
+while (inbytes == GNUTLS_E_AGAIN);
-/*************************************************
-* Deal with logging errors during I/O *
-*************************************************/
+if (smtp_receive_timeout > 0) ALARM_CLR(0);
-/* We have to get the identity of the peer from saved data.
+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();
-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
+/* 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. */
-Returns: nothing
-*/
+if (sigalrm_seen)
+ {
+ DEBUG(D_tls) debug_printf("Got tls read timeout\n");
+ state->xfer_error = TRUE;
+ return FALSE;
+ }
-static void
-record_io_error(int ec, uschar *when, uschar *text)
-{
-const char *msg;
+else if (inbytes == 0)
+ {
+ DEBUG(D_tls) debug_printf("Got TLS_EOF\n");
+ tls_close(NULL, TLS_NO_SHUTDOWN);
+ return FALSE;
+ }
-if (ec == GNUTLS_E_FATAL_ALERT_RECEIVED)
- msg = string_sprintf("%s: %s", gnutls_strerror(ec),
- gnutls_alert_get_name(gnutls_alert_get(tls_session)));
-else
- msg = gnutls_strerror(ec);
+/* Handle genuine errors */
-tls_error(when, client_host, msg);
+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");
+/* Something in the buffer; return next uschar */
- receive_getc = smtp_getc;
- receive_ungetc = smtp_ungetc;
- receive_feof = smtp_feof;
- receive_ferror = smtp_ferror;
- receive_smtp_buffered = smtp_buffered;
+return state->xfer_buffer[state->xfer_buffer_lwm++];
+}
- gnutls_deinit(tls_session);
- tls_session = NULL;
- tls_active = -1;
- tls_cipher = NULL;
- tls_peerdn = NULL;
+uschar *
+tls_getbuf(unsigned * len)
+{
+exim_gnutls_state_st * state = &state_server;
+unsigned size;
+uschar * buf;
- return smtp_getc();
+if (state->xfer_buffer_lwm >= state->xfer_buffer_hwm)
+ if (!tls_refill(*len))
+ {
+ if (!state->xfer_error) return smtp_getbuf(len);
+ *len = 0;
+ return NULL;
}
- /* Handle genuine errors */
+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;
+}
- else if (inbytes < 0)
- {
- record_io_error(inbytes, US"recv", NULL);
- ssl_xfer_error = 1;
- return EOF;
- }
+
+void
+tls_get_cache()
+{
#ifndef DISABLE_DKIM
- dkim_exim_verify_feed(ssl_xfer_buffer, inbytes);
+exim_gnutls_state_st * state = &state_server;
+int n = state->xfer_buffer_hwm - state->xfer_buffer_lwm;
+if (n > 0)
+ dkim_exim_verify_feed(state->xfer_buffer+state->xfer_buffer_lwm, n);
#endif
- ssl_xfer_buffer_hwm = inbytes;
- ssl_xfer_buffer_lwm = 0;
- }
-
+}
-/* Something in the buffer; return next uschar */
-return ssl_xfer_buffer[ssl_xfer_buffer_lwm++];
+BOOL
+tls_could_read(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(%p, %p, " 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);
+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) gnutls_record_cork(state->session);
+#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(%p, %p, " SIZE_T_FMT ")\n",
+ state->session, buff, left);
+
+ do
+ outbytes = gnutls_record_send(state->session, buff, left);
+ while (outbytes == GNUTLS_E_AGAIN);
- DEBUG(D_tls) debug_printf("outbytes=%d\n", outbytes);
+ DEBUG(D_tls) debug_printf("outbytes=" SSIZE_T_FMT "\n", outbytes);
if (outbytes < 0)
{
- record_io_error(outbytes, US"send", NULL);
+ 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)
+ {
+ if (!more) (void) gnutls_record_uncork(state->session, 0);
+ state->corked = more;
+ }
+#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)
{
-if (tls_active < 0) return; /* TLS was not active */
+unsigned int r;
+int i, needed_len;
+uschar smallbuf[sizeof(r)];
-if (shutdown)
+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)
+{
+ return vaguely_random_number_fallback(max);
+}
+#endif /* HAVE_GNUTLS_RND */
+
+
+
+
+/*************************************************
+* 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;
-gnutls_deinit(tls_session);
-tls_session = NULL;
+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);
+
+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, errpos - CS expciphers, errpos));
+
+#undef return_deinit
+#undef validate_check_rc
+#ifndef GNUTLS_AUTO_GLOBAL_INIT
gnutls_global_deinit();
+#endif
-tls_active = -1;
+return NULL;
}
gnutls_check_version(NULL));
}
+#endif /*!MACRO_PREDEF*/
+/* vi: aw ai sw=2
+*/
/* End of tls-gnu.c */
git://git.exim.org / exim.git / blobdiff