* Exim - an Internet mail transport agent *
*************************************************/
-/* Copyright (c) University of Cambridge 1995 - 2009 */
+/* Copyright (c) University of Cambridge 1995 - 2012 */
/* 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.
-/* Note: This appears to be using an old API from compat.h; it is likely that
-someone familiary with GnuTLS programming could rework a lot of this to a
-modern API and perhaps remove the explicit knowledge of crypto algorithms from
-Exim. Such a re-work would be most welcome and we'd sacrifice support for
-older GnuTLS releases without too many qualms -- maturity and experience
-in crypto libraries tends to improve their robustness against attack.
-Frankly, if you maintain it, you decide what's supported and what isn't. */
+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
+Mavroyanopoulos. 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).
-#include <gnutls/gnutls.h>
-#include <gnutls/x509.h>
+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.
-#define UNKNOWN_NAME "unknown"
-#define DH_BITS 1024
-#define PARAM_SIZE 2*1024
+(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>
-/* Values for verify_requirment */
+/* GnuTLS 2 vs 3
-enum { VERIFY_NONE, VERIFY_OPTIONAL, VERIFY_REQUIRED };
+GnuTLS 3 only:
+ gnutls_global_set_audit_log_function()
-/* Local static variables for GNUTLS */
+Changes:
+ gnutls_certificate_verify_peers2(): is new, drop the 2 for old version
+*/
-static host_item *client_host;
+/* Local static variables for GnuTLS */
-static gnutls_dh_params dh_params = NULL;
+/* Values for verify_requirement */
-static gnutls_certificate_server_credentials x509_cred = NULL;
-static gnutls_session tls_session = NULL;
+enum peer_verify_requirement { VERIFY_NONE, VERIFY_OPTIONAL, VERIFY_REQUIRED };
-static char ssl_errstring[256];
+/* 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 int ssl_session_timeout = 200;
-static int verify_requirement;
+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.
-/* Priorities for TLS algorithms to use. In each case there's a default table,
-and space into which it can be copied and altered. */
+Not handled here: globals tls_active, tls_bits, tls_cipher, tls_peerdn,
+tls_certificate_verified, tls_channelbinding_b64, tls_sni.
+*/
-static const int default_proto_priority[16] = {
- /* These are gnutls_protocol_t enum values */
-#if GNUTLS_VERSION_MAJOR > 1 || GNUTLS_VERSION_MINOR >= 7
- GNUTLS_TLS1_2,
-#endif
-#if GNUTLS_VERSION_MAJOR > 1 || GNUTLS_VERSION_MINOR >= 2
- GNUTLS_TLS1_1,
-#endif
- GNUTLS_TLS1,
- GNUTLS_SSL3,
- 0 };
+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;
+ BOOL trigger_sni_changes;
+ const struct host_item *host;
+ uschar *peerdn;
+ 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_sni;
+ uschar *exp_tls_verify_certificates;
+ uschar *exp_tls_crl;
+ uschar *exp_tls_require_ciphers;
+
+ uschar *xfer_buffer;
+ int xfer_buffer_lwm;
+ int xfer_buffer_hwm;
+ int xfer_eof;
+ int xfer_error;
+
+ uschar cipherbuf[256];
+} exim_gnutls_state_st;
+
+static const exim_gnutls_state_st exim_gnutls_state_init = {
+ NULL, NULL, NULL, VERIFY_NONE, -1, -1, FALSE, FALSE,
+ NULL, NULL, NULL,
+ NULL, NULL, NULL, NULL, NULL, NULL,
+ NULL, NULL, NULL, NULL, NULL, NULL,
+ NULL, 0, 0, 0, 0,
+ ""
+};
-static int proto_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. */
-static const int default_kx_priority[16] = {
- GNUTLS_KX_RSA,
- GNUTLS_KX_DHE_DSS,
- GNUTLS_KX_DHE_RSA,
- 0 };
+static exim_gnutls_state_st state_server, state_client;
+static exim_gnutls_state_st *current_global_tls_state;
-static int kx_priority[16];
+/* dh_params are initialised once within the lifetime of a process using TLS;
+if we used TLS in a long-lived daemon, we'd have to reconsider this. But we
+don't want to repeat this. */
-static 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 gnutls_dh_params_t dh_server_params = NULL;
-static int cipher_priority[16];
+/* No idea how this value was chosen; preserving it. Default is 3600. */
-static const int default_mac_priority[16] = {
- GNUTLS_MAC_SHA,
- GNUTLS_MAC_MD5,
- 0 };
+static const int ssl_session_timeout = 200;
-static int mac_priority[16];
+static const char * const exim_default_gnutls_priority = "NORMAL";
-/* These two are currently not changeable. */
+/* Guard library core initialisation */
-static const int comp_priority[16] = { GNUTLS_COMP_NULL, 0 };
-static const int cert_type_priority[16] = { GNUTLS_CRT_X509, 0 };
+static BOOL exim_gnutls_base_init_done = FALSE;
-/* Tables of priority names and equivalent numbers */
-typedef struct pri_item {
- uschar *name;
- int *values;
-} pri_item;
+/* ------------------------------------------------------------------------ */
+/* Callback declarations */
+static void exim_gnutls_logger_cb(int level, const char *message);
+static int exim_sni_handling_cb(gnutls_session_t session);
-#if GNUTLS_VERSION_MAJOR > 1 || GNUTLS_VERSION_MINOR >= 7
-static int tls1_2_codes[] = { GNUTLS_TLS1_2, 0 };
-#endif
-#if GNUTLS_VERSION_MAJOR > 1 || GNUTLS_VERSION_MINOR >= 2
-static int tls1_1_codes[] = { GNUTLS_TLS1_1, 0 };
-#endif
-/* more recent libraries define this as an equivalent value to the
-canonical GNUTLS_TLS1_0; since they're the same, we stick to the
-older name. */
-static int tls1_0_codes[] = { GNUTLS_TLS1, 0 };
-static int ssl3_codes[] = { GNUTLS_SSL3, 0 };
-
-static pri_item proto_index[] = {
-#if GNUTLS_VERSION_MAJOR > 1 || GNUTLS_VERSION_MINOR >= 7
- { US"TLS1.2", tls1_2_codes },
-#endif
-#if GNUTLS_VERSION_MAJOR > 1 || GNUTLS_VERSION_MINOR >= 2
- { US"TLS1.1", tls1_1_codes },
-#endif
- { US"TLS1.0", tls1_0_codes },
- { US"TLS1", tls1_0_codes },
- { US"SSL3", ssl3_codes }
-};
+/* ------------------------------------------------------------------------ */
+/* macros */
+#define MAX_HOST_LEN 255
-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 };
-
-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 }
-};
+/* 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. */
+#define EXIM_GNUTLS_LIBRARY_LOG_LEVEL -1
+#define EXIM_CLIENT_DH_MIN_BITS 1024
-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 }
-};
+#define exim_gnutls_err_check(Label) do { \
+ if (rc != GNUTLS_E_SUCCESS) { return tls_error((Label), gnutls_strerror(rc), host); } } while (0)
+#define exim_gnutls_err_debugreturn0(Label) do { \
+ if (rc != GNUTLS_E_SUCCESS) { \
+ DEBUG(D_tls) debug_printf("TLS failure: %s: %s", (Label), gnutls_strerror(rc)); \
+ return 0; } } while (0)
-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 }
-};
+#define expand_check_tlsvar(Varname) expand_check(state->Varname, US #Varname, &state->exp_##Varname)
+#if GNUTLS_VERSION_NUMBER >= 0x020c00
+#define HAVE_GNUTLS_SESSION_CHANNEL_BINDING
+#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
Returns: OK/DEFER/FAIL
*/
static int
-tls_error(uschar *prefix, host_item *host, const char *msg)
+tls_error(const uschar *prefix, const char *msg, const host_item *host)
{
-if (host == NULL)
+if (host)
+ {
+ 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;
+ }
+else
{
uschar *conn_info = smtp_get_connection_info();
- if (strncmp(conn_info, "SMTP ", 5) == 0)
+ if (Ustrncmp(conn_info, US"SMTP ", 5) == 0)
conn_info += 5;
log_write(0, LOG_MAIN, "TLS error on %s (%s)%s%s",
- conn_info, prefix, msg ? ": " : "", msg ? msg : "");
+ conn_info, prefix, msg ? ": " : "", msg ? msg : "");
return DEFER;
}
-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;
- }
}
+
/*************************************************
-* Verify certificate *
+* Deal with logging errors during I/O *
*************************************************/
-/* Called after a successful handshake, when certificate verification is
-required or optional, for both server and client.
+/* We have to get the identity of the peer from saved data.
-Arguments:
- session GNUTLS session
- error where to put text giving a reason for failure
+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 ec is 0
-Returns: TRUE/FALSE
+Returns: nothing
*/
-static BOOL
-verify_certificate(gnutls_session session, const char **error)
+static void
+record_io_error(exim_gnutls_state_st *state, int rc, uschar *when, uschar *text)
{
-int rc = -1;
-uschar *dn_string = US"";
-const gnutls_datum *cert;
-unsigned int verify, cert_size = 0;
+const char *msg;
-*error = NULL;
+if (rc == GNUTLS_E_FATAL_ALERT_RECEIVED)
+ msg = CS string_sprintf("%s: %s", US gnutls_strerror(rc),
+ US gnutls_alert_get_name(gnutls_alert_get(state->session)));
+else
+ msg = gnutls_strerror(rc);
-/* 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. */
+tls_error(when, msg, state->host);
+}
-cert = gnutls_certificate_get_peers(session, &cert_size);
-if (cert != NULL)
- {
- uschar buff[1024];
- gnutls_x509_crt gcert;
- gnutls_x509_crt_init(&gcert);
- dn_string = US"unknown";
- 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);
- }
- rc = gnutls_certificate_verify_peers2(session, &verify);
- }
-else
- {
- DEBUG(D_tls) debug_printf("no peer certificate supplied\n");
- verify = GNUTLS_CERT_INVALID;
- *error = "not supplied";
- }
+/*************************************************
+* Set various Exim expansion vars *
+*************************************************/
-/* Handle the result of verification. INVALID seems to be set as well
-as REVOKED, but leave the test for both. */
+/* 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.
-if ((rc < 0) || (verify & (GNUTLS_CERT_INVALID|GNUTLS_CERT_REVOKED)) != 0)
- {
- 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
+Make sure anything set here is inset in tls_getc().
+
+Sets:
+ tls_active fd
+ tls_bits strength indicator
+ tls_certificate_verified bool indicator
+ tls_channelbinding_b64 for some SASL mechanisms
+ tls_cipher a string
+ tls_peerdn a string
+ tls_sni a (UTF-8) string
+Also:
+ current_global_tls_state for API limitations
+
+Argument:
+ state the relevant exim_gnutls_state_st *
+*/
+
+static void
+extract_exim_vars_from_tls_state(exim_gnutls_state_st *state)
+{
+gnutls_protocol_t protocol;
+gnutls_cipher_algorithm_t cipher;
+gnutls_kx_algorithm_t kx;
+gnutls_mac_algorithm_t mac;
+uschar *p;
+#ifdef HAVE_GNUTLS_SESSION_CHANNEL_BINDING
+int old_pool;
+int rc;
+gnutls_datum_t channel;
+#endif
+
+current_global_tls_state = state;
+
+tls_active = state->fd_out;
+
+cipher = gnutls_cipher_get(state->session);
+/* returns size in "bytes" */
+tls_bits = gnutls_cipher_get_key_size(cipher) * 8;
+
+if (!*state->cipherbuf)
{
- tls_certificate_verified = TRUE;
- DEBUG(D_tls) debug_printf("TLS certificate verified: peerdn=%s\n",
- dn_string);
+ protocol = gnutls_protocol_get_version(state->session);
+ mac = gnutls_mac_get(state->session);
+ kx = gnutls_kx_get(state->session);
+
+ string_format(state->cipherbuf, sizeof(state->cipherbuf),
+ "%s:%s:%u",
+ gnutls_protocol_get_name(protocol),
+ gnutls_cipher_suite_get_name(kx, cipher, mac),
+ tls_bits);
+
+ /* 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 (p = state->cipherbuf; *p != '\0'; ++p)
+ if (isspace(*p))
+ *p = '-';
}
+tls_cipher = state->cipherbuf;
+
+DEBUG(D_tls) debug_printf("cipher: %s\n", tls_cipher);
+
+tls_certificate_verified = state->peer_cert_verified;
-tls_peerdn = dn_string;
-return TRUE; /* accept */
+/* note that tls_channelbinding_b64 is not saved to the spool file, since it's
+only available for use for authenticators while this TLS session is running. */
+
+tls_channelbinding_b64 = NULL;
+#ifdef HAVE_GNUTLS_SESSION_CHANNEL_BINDING
+channel.data = NULL;
+channel.size = 0;
+rc = gnutls_session_channel_binding(state->session, GNUTLS_CB_TLS_UNIQUE, &channel);
+if (rc) {
+ DEBUG(D_tls) debug_printf("Channel binding error: %s\n", gnutls_strerror(rc));
+} else {
+ old_pool = store_pool;
+ store_pool = POOL_PERM;
+ tls_channelbinding_b64 = auth_b64encode(channel.data, (int)channel.size);
+ store_pool = old_pool;
+ DEBUG(D_tls) debug_printf("Have channel bindings cached for possible auth usage.\n");
+}
+#endif
+
+tls_peerdn = state->peerdn;
+
+tls_sni = state->received_sni;
}
+
/*************************************************
* Setup up DH parameters *
*************************************************/
*/
static int
-init_dh(host_item *host)
+init_server_dh(void)
{
-int fd;
-int ret;
+int fd, rc;
+unsigned int dh_bits;
gnutls_datum m;
-uschar filename[200];
+uschar filename[PATH_MAX];
+size_t sz;
+host_item *host = NULL; /* dummy for macros */
+const char * const dh_param_fn_ext = "normal"; /* change as dh_bits changes */
-/* Initialize the data structures for holding the parameters */
+DEBUG(D_tls) debug_printf("Initialising GnuTLS server params.\n");
-ret = gnutls_dh_params_init(&dh_params);
-if (ret < 0) return tls_error(US"init dh_params", host, gnutls_strerror(ret));
+rc = gnutls_dh_params_init(&dh_server_params);
+exim_gnutls_err_check(US"gnutls_dh_params_init");
-/* Set up the name of the cache file */
+/* If you change this, also change dh_param_fn_ext so that we can use a
+different filename and ensure we have sufficient bits. */
+dh_bits = gnutls_sec_param_to_pk_bits(GNUTLS_PK_DH, GNUTLS_SEC_PARAM_NORMAL);
+if (!dh_bits)
+ return tls_error(US"gnutls_sec_param_to_pk_bits() failed", NULL, NULL);
-if (!string_format(filename, sizeof(filename), "%s/gnutls-params",
- spool_directory))
- return tls_error(US"overlong filename", host, NULL);
+if (!string_format(filename, sizeof(filename),
+ "%s/gnutls-params-%s", spool_directory, dh_param_fn_ext))
+ return tls_error(US"overlong filename", NULL, NULL);
/* Open the cache file for reading and if successful, read it and set up the
parameters. */
if (fd >= 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(US"TLS cache stat failed", strerror(saved_errno), NULL);
+ }
+ if (!S_ISREG(statbuf.st_mode))
{
(void)close(fd);
- return tls_error(US"TLS cache stat failed", host, strerror(errno));
+ return tls_error(US"TLS cache not a file", NULL, NULL);
+ }
+ fp = fdopen(fd, "rb");
+ if (!fp)
+ {
+ saved_errno = errno;
+ (void)close(fd);
+ return tls_error(US"fdopen(TLS cache stat fd) failed",
+ strerror(saved_errno), NULL);
}
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");
+ {
+ fclose(fp);
+ return tls_error(US"malloc failed", strerror(errno), NULL);
+ }
+ sz = fread(m.data, m.size, 1, fp);
+ if (!sz)
+ {
+ saved_errno = errno;
+ fclose(fp);
+ free(m.data);
+ return tls_error(US"fread failed", strerror(saved_errno), NULL);
+ }
+ fclose(fp);
+ rc = gnutls_dh_params_import_pkcs3(dh_server_params, &m, GNUTLS_X509_FMT_PEM);
free(m.data);
+ exim_gnutls_err_check(US"gnutls_dh_params_import_pkcs3");
+ 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);
/* 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];
+ uschar *temp_fn;
- 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));
+ if ((PATH_MAX - Ustrlen(filename)) < 10)
+ return tls_error(US"Filename too long to generate replacement",
+ CS filename, NULL);
- /* Write the parameters to a file in the spool directory so that we
- can use them from other Exim processes. */
-
- sprintf(CS tempfilename, "%s-%d", filename, (int)getpid());
- fd = Uopen(tempfilename, O_WRONLY|O_CREAT, 0400);
+ temp_fn = string_copy(US "%s.XXXXXXX");
+ fd = mkstemp(CS temp_fn); /* modifies temp_fn */
if (fd < 0)
- return tls_error(string_open_failed(errno, "%s for writing", filename),
- host, NULL);
+ return tls_error(US"Unable to open temp file", strerror(errno), NULL);
(void)fchown(fd, exim_uid, exim_gid); /* Probably not necessary */
- /* export the parameters in a format that can be generated using GNUTLS'
- * certtool or other programs.
- *
- * The commands for certtool are:
- * $ certtool --generate-dh-params --bits 1024 > params
- */
-
- m.size = PARAM_SIZE;
+ DEBUG(D_tls) debug_printf("generating %d bits Diffie-Hellman key ...\n", dh_bits);
+ rc = gnutls_dh_params_generate2(dh_server_params, dh_bits);
+ exim_gnutls_err_check(US"gnutls_dh_params_generate2");
+
+ /* 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;
+ rc = gnutls_dh_params_export_pkcs3(dh_server_params, GNUTLS_X509_FMT_PEM,
+ m.data, &sz);
+ if (rc != GNUTLS_E_SHORT_MEMORY_BUFFER)
+ exim_gnutls_err_check(US"gnutls_dh_params_export_pkcs3(NULL) sizing");
+ m.size = sz;
m.data = malloc(m.size);
if (m.data == NULL)
- return tls_error(US"memory allocation failed", host, strerror(errno));
-
- 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));
-
- 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));
+ return tls_error(US"memory allocation failed", strerror(errno), NULL);
+ rc = gnutls_dh_params_export_pkcs3(dh_server_params, GNUTLS_X509_FMT_PEM,
+ m.data, &sz);
+ if (rc != GNUTLS_E_SUCCESS)
+ {
+ free(m.data);
+ exim_gnutls_err_check(US"gnutls_dh_params_export_pkcs3() real");
+ }
+ sz = write_to_fd_buf(fd, m.data, (size_t) m.size);
+ if (sz != m.size)
+ {
+ free(m.data);
+ return tls_error(US"TLS cache write D-H params failed",
+ strerror(errno), NULL);
+ }
free(m.data);
- (void)close(fd);
+ sz = write_to_fd_buf(fd, US"\n", 1);
+ if (sz != 1)
+ return tls_error(US"TLS cache write D-H params final newline failed",
+ strerror(errno), NULL);
+
+ rc = close(fd);
+ if (rc)
+ return tls_error(US"TLS cache write close() failed",
+ strerror(errno), NULL);
- 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(string_sprintf("failed to rename \"%s\" as \"%s\"",
+ temp_fn, filename), strerror(errno), NULL);
- DEBUG(D_tls) debug_printf("wrote D-H parameters to file %s\n", filename);
+ DEBUG(D_tls) debug_printf("wrote D-H parameters to file \"%s\"\n", filename);
}
-DEBUG(D_tls) debug_printf("initialized D-H parameters\n");
+DEBUG(D_tls) debug_printf("initialized server D-H parameters\n");
return OK;
}
/*************************************************
-* Initialize for GnuTLS *
+* Variables re-expanded post-SNI *
*************************************************/
-/* Called from both server and client code. In the case of a server, errors
-before actual TLS negotiation return DEFER.
+/* 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:
- host connected host, if client; NULL if server
- certificate certificate file
- privatekey private key file
- cas CA certs file
- crl CRL file
+ state exim_gnutls_state_st *
Returns: OK/DEFER/FAIL
*/
static int
-tls_init(host_item *host, uschar *certificate, uschar *privatekey, uschar *cas,
- uschar *crl)
+tls_expand_session_files(exim_gnutls_state_st *state)
{
int rc;
-uschar *cert_expanded, *key_expanded, *cas_expanded, *crl_expanded;
-
-client_host = host;
+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 (!state->host)
+ {
+ if (!state->received_sni)
+ {
+ if (Ustrstr(state->tls_certificate, US"tls_sni"))
+ {
+ DEBUG(D_tls) debug_printf("We will re-expand TLS session files if we receive SNI.\n");
+ state->trigger_sni_changes = TRUE;
+ }
+ }
+ else
+ {
+ 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;
+ }
+ }
-rc = gnutls_global_init();
-if (rc < 0) return tls_error(US"tls-init", host, gnutls_strerror(rc));
+/* 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. */
-/* Create D-H parameters, or read them from the cache file. This function does
-its own SMTP error messaging. */
+/* check if we at least have a certificate, before doing expensive
+D-H generation. */
-rc = init_dh(host);
-if (rc != OK) return rc;
+if (!expand_check_tlsvar(tls_certificate))
+ return DEFER;
-/* Create the credentials structure */
+/* certificate is mandatory in server, optional in client */
-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. */
+if ((state->exp_tls_certificate == NULL) ||
+ (*state->exp_tls_certificate == '\0'))
+ {
+ if (state->host == NULL)
+ return tls_error(US"no TLS server certificate is specified", NULL, NULL);
+ else
+ DEBUG(D_tls) debug_printf("TLS: no client certificate specified; okay\n");
+ }
-if (!expand_check(certificate, US"tls_certificate", &cert_expanded))
+if (state->tls_privatekey && !expand_check_tlsvar(tls_privatekey))
return DEFER;
-key_expanded = NULL;
-if (privatekey != NULL)
+/* tls_privatekey is optional, defaulting to same file as certificate */
+
+if (state->tls_privatekey == NULL || *state->tls_privatekey == '\0')
{
- if (!expand_check(privatekey, US"tls_privatekey", &key_expanded))
- return DEFER;
+ state->tls_privatekey = state->tls_certificate;
+ state->exp_tls_privatekey = state->exp_tls_certificate;
}
-/* 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;
-/* Set the certificate and private keys */
-
-if (cert_expanded != NULL)
+if (state->exp_tls_certificate && *state->exp_tls_certificate)
{
+ BOOL setit = TRUE;
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)
+ state->exp_tls_certificate, state->exp_tls_privatekey);
+
+ if (state->received_sni)
{
- uschar *msg = string_sprintf("cert/key setup: cert=%s key=%s",
- cert_expanded, key_expanded);
- return tls_error(msg, host, gnutls_strerror(rc));
+ if ((Ustrcmp(state->exp_tls_certificate, saved_tls_certificate) == 0) &&
+ (Ustrcmp(state->exp_tls_privatekey, saved_tls_privatekey) == 0))
+ {
+ DEBUG(D_tls) debug_printf("cert and key unchanged with SNI.\n");
+ setit = FALSE;
+ }
+ else
+ {
+ DEBUG(D_tls) debug_printf("SNI changed cert/key pair.\n");
+ }
}
- }
-/* A certificate is mandatory in a server, but not in a client */
-
-else
- {
- 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");
+ if (setit)
+ {
+ rc = gnutls_certificate_set_x509_key_file(state->x509_cred,
+ CS state->exp_tls_certificate, CS state->exp_tls_privatekey,
+ GNUTLS_X509_FMT_PEM);
+ exim_gnutls_err_check(
+ string_sprintf("cert/key setup: cert=%s key=%s",
+ state->exp_tls_certificate, state->exp_tls_privatekey));
+ }
}
/* Set the trusted CAs file if one is provided, and then add the CRL if one is
in that case, certificate verification fails, which seems to be the correct
behaviour. */
-if (cas != NULL)
+if (state->tls_verify_certificates && *state->tls_verify_certificates)
{
struct stat statbuf;
+ BOOL setit_vc = TRUE, setit_crl = TRUE;
- if (!expand_check(cas, US"tls_verify_certificates", &cas_expanded))
+ if (!expand_check_tlsvar(tls_verify_certificates))
return DEFER;
+ if (state->tls_crl && *state->tls_crl)
+ if (!expand_check_tlsvar(tls_crl))
+ return DEFER;
- if (stat(CS cas_expanded, &statbuf) < 0)
+ if (state->received_sni)
+ {
+ if (Ustrcmp(state->exp_tls_verify_certificates, saved_tls_verify_certificates) == 0)
+ setit_vc = FALSE;
+ if (Ustrcmp(state->exp_tls_crl, saved_tls_crl) == 0)
+ setit_crl = FALSE;
+ }
+
+ /* nb: early exit; change if add more expansions to this function */
+ if (!(setit_vc || setit_crl))
+ return OK;
+
+ if (Ustat(state->exp_tls_verify_certificates, &statbuf) < 0)
{
log_write(0, LOG_MAIN|LOG_PANIC, "could not stat %s "
- "(tls_verify_certificates): %s", cas_expanded, strerror(errno));
+ "(tls_verify_certificates): %s", state->exp_tls_verify_certificates,
+ strerror(errno));
+ return DEFER;
+ }
+
+ if (!S_ISREG(statbuf.st_mode))
+ {
+ DEBUG(D_tls)
+ debug_printf("verify certificates path is not a file: \"%s\"\n%s\n",
+ state->exp_tls_verify_certificates,
+ S_ISDIR(statbuf.st_mode)
+ ? " it's a directory, that's OpenSSL, this is GnuTLS"
+ : " (not a directory either)");
+ log_write(0, LOG_MAIN|LOG_PANIC,
+ "tls_verify_certificates \"%s\" is not a file",
+ state->exp_tls_verify_certificates);
return DEFER;
}
DEBUG(D_tls) debug_printf("verify certificates = %s size=" OFF_T_FMT "\n",
- cas_expanded, statbuf.st_size);
+ state->exp_tls_verify_certificates, statbuf.st_size);
- /* If the cert file is empty, there's no point in loading the CRL file. */
+ /* If the CA cert file is empty, there's no point in loading the CRL file,
+ as we aren't verifying, so checking for revocation is pointless. */
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 (crl != NULL && *crl != 0)
+ if (setit_vc)
{
- 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));
+ cert_count = gnutls_certificate_set_x509_trust_file(state->x509_cred,
+ CS state->exp_tls_verify_certificates, GNUTLS_X509_FMT_PEM);
+ if (cert_count < 0)
+ {
+ rc = cert_count;
+ exim_gnutls_err_check(US"gnutls_certificate_set_x509_trust_file");
+ }
+ DEBUG(D_tls) debug_printf("Added %d certificate authorities.\n", cert_count);
}
- }
- }
-/* Associate the parameters with the x509 credentials structure. */
-
-gnutls_certificate_set_dh_params(x509_cred, dh_params);
+ if (setit_crl && state->tls_crl && *state->tls_crl)
+ {
+ if (state->exp_tls_crl && *state->exp_tls_crl)
+ {
+ DEBUG(D_tls) debug_printf("loading CRL file = %s\n", state->exp_tls_crl);
+ rc = gnutls_certificate_set_x509_crl_file(state->x509_cred,
+ CS state->exp_tls_crl, GNUTLS_X509_FMT_PEM);
+ exim_gnutls_err_check(US"gnutls_certificate_set_x509_crl_file");
+ }
+ }
+ } /* statbuf.st_size */
+ } /* tls_verify_certificates */
-DEBUG(D_tls) debug_printf("initialized certificate stuff\n");
return OK;
+/* also above, during verify_certificates/crl, during SNI, if unchanged */
}
/*************************************************
-* Remove from a priority list *
+* Initialize for GnuTLS *
*************************************************/
-/* Cautiously written so that it will remove duplicates if present.
+/* Called from both server and client code. In the case of a server, errors
+before actual TLS negotiation return DEFER.
Arguments:
- list a zero-terminated list
- remove_list a zero-terminated list to be removed
+ 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
-Returns: nothing
+Returns: OK/DEFER/FAIL
*/
-static void
-remove_priority(int *list, int *remove_list)
+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)
{
-for (; *remove_list != 0; remove_list++)
+exim_gnutls_state_st *state;
+int rc;
+size_t sz;
+const char *errpos;
+uschar *p;
+BOOL want_default_priorities;
+
+if (!exim_gnutls_base_init_done)
{
- int *p = list;
- while (*p != 0)
+ DEBUG(D_tls) debug_printf("GnuTLS global init required.\n");
+
+ rc = gnutls_global_init();
+ exim_gnutls_err_check(US"gnutls_global_init");
+
+#if EXIM_GNUTLS_LIBRARY_LOG_LEVEL >= 0
+ DEBUG(D_tls)
{
- if (*p == *remove_list)
- {
- int *pp = p;
- do { pp[0] = pp[1]; pp++; } while (*pp != 0);
- }
- else p++;
+ gnutls_global_set_log_function(exim_gnutls_logger_cb);
+ /* arbitrarily chosen level; bump upto 9 for more */
+ gnutls_global_set_log_level(EXIM_GNUTLS_LIBRARY_LOG_LEVEL);
}
+#endif
+
+ exim_gnutls_base_init_done = TRUE;
}
-}
+if (host)
+ {
+ state = &state_client;
+ memcpy(state, &exim_gnutls_state_init, sizeof(exim_gnutls_state_init));
+ DEBUG(D_tls) debug_printf("initialising GnuTLS client session\n");
+ rc = gnutls_init(&state->session, GNUTLS_CLIENT);
+ }
+else
+ {
+ state = &state_server;
+ memcpy(state, &exim_gnutls_state_init, sizeof(exim_gnutls_state_init));
+ DEBUG(D_tls) debug_printf("initialising GnuTLS server session\n");
+ rc = gnutls_init(&state->session, GNUTLS_SERVER);
+ }
+exim_gnutls_err_check(US"gnutls_init");
+state->host = host;
-/*************************************************
-* Add to a priority list *
-*************************************************/
+state->tls_certificate = certificate;
+state->tls_privatekey = privatekey;
+state->tls_sni = sni;
+state->tls_verify_certificates = cas;
+state->tls_crl = crl;
-/* Cautiously written to check the list size
+rc = gnutls_certificate_allocate_credentials(&state->x509_cred);
+exim_gnutls_err_check(US"gnutls_certificate_allocate_credentials");
-Arguments:
- list a zero-terminated list
- list_max maximum offset in the list
- add_list a zero-terminated list to be added
+/* This handles the variables that might get re-expanded after TLS SNI;
+that's tls_certificate, tls_privatekey, tls_verify_certificates, tls_crl */
-Returns: TRUE if OK; FALSE if list overflows
-*/
+DEBUG(D_tls)
+ debug_printf("Expanding various TLS configuration options for session credentials.\n");
+rc = tls_expand_session_files(state);
+if (rc != OK) return rc;
-static BOOL
-add_priority(int *list, int list_max, int *add_list)
-{
-int next = 0;
-while (list[next] != 0) next++;
-while (*add_list != 0)
+/* 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 (!host)
{
- if (next >= list_max) return FALSE;
- list[next++] = *add_list++;
+ rc = init_server_dh();
+ if (rc != OK) return rc;
+ gnutls_certificate_set_dh_params(state->x509_cred, dh_server_params);
}
-list[next] = 0;
-return TRUE;
-}
-
-
-
-/*************************************************
-* Adjust a priority list *
-*************************************************/
-
-/* This function is called to adjust the lists of cipher algorithms, MAC
-algorithms, key-exchange methods, and protocols.
-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
+/* Link the credentials to the session. */
+rc = gnutls_credentials_set(state->session, GNUTLS_CRD_CERTIFICATE, state->x509_cred);
+exim_gnutls_err_check(US"gnutls_credentials_set");
- which text for an error message
+/* set SNI in client, only */
+if (host)
+ {
+ if (!expand_check_tlsvar(tls_sni))
+ return DEFER;
+ if (state->exp_tls_sni && *state->exp_tls_sni)
+ {
+ DEBUG(D_tls)
+ debug_printf("Setting TLS client SNI to \"%s\"\n", state->exp_tls_sni);
+ sz = Ustrlen(state->exp_tls_sni);
+ rc = gnutls_server_name_set(state->session,
+ GNUTLS_NAME_DNS, state->exp_tls_sni, sz);
+ exim_gnutls_err_check(US"gnutls_server_name_set");
+ }
+ }
+else if (state->tls_sni)
+ DEBUG(D_tls) debug_printf("*** PROBABLY A BUG *** " \
+ "have an SNI set for a client [%s]\n", state->tls_sni);
-Returns: FALSE if the table overflows, else TRUE
-*/
+/* This is the priority string support,
+http://www.gnu.org/software/gnutls/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. */
-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;
+want_default_priorities = TRUE;
-while ((t = string_nextinlist(&s, &sep, big_buffer, big_buffer_size)) != NULL)
+if (state->tls_require_ciphers && *state->tls_require_ciphers)
{
- int i;
- BOOL exclude = t[0] == '!';
- if (first && !exclude) plist[0] = 0;
- first = FALSE;
- for (i = 0; i < isize; i++)
+ if (!expand_check_tlsvar(tls_require_ciphers))
+ return DEFER;
+ if (state->exp_tls_require_ciphers && *state->exp_tls_require_ciphers)
{
- 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;
- }
- }
- }
- }
+ DEBUG(D_tls) debug_printf("GnuTLS session cipher/priority \"%s\"\n",
+ state->exp_tls_require_ciphers);
+
+ rc = gnutls_priority_init(&state->priority_cache,
+ CS state->exp_tls_require_ciphers, &errpos);
+ want_default_priorities = FALSE;
+ p = state->exp_tls_require_ciphers;
}
}
+if (want_default_priorities)
+ {
+ rc = gnutls_priority_init(&state->priority_cache,
+ exim_default_gnutls_priority, &errpos);
+ p = US exim_default_gnutls_priority;
+ }
-DEBUG(D_tls)
+exim_gnutls_err_check(string_sprintf(
+ "gnutls_priority_init(%s) failed at offset %ld, \"%.6s..\"",
+ p, errpos - CS p, errpos));
+
+rc = gnutls_priority_set(state->session, state->priority_cache);
+exim_gnutls_err_check(US"gnutls_priority_set");
+
+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 (gnutls_compat_mode)
{
- int *ptr = plist;
- debug_printf("adjusted %s priorities:", which);
- while (*ptr != 0) debug_printf(" %d", *ptr++);
- debug_printf("\n");
+#if LIBGNUTLS_VERSION_NUMBER >= 0x020104
+ DEBUG(D_tls) debug_printf("lowering GnuTLS security, compatibility mode\n");
+ gnutls_session_enable_compatibility_mode(state->session);
+#else
+ DEBUG(D_tls) debug_printf("Unable to set gnutls_compat_mode - GnuTLS version too old\n");
+#endif
}
-return TRUE;
+*caller_state = state;
+/* needs to happen before callbacks during handshake */
+current_global_tls_state = state;
+return OK;
}
/*************************************************
-* Initialize a single GNUTLS session *
+* Extract peer information *
*************************************************/
-/* 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.
-
-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.
+Only this is allowed to set state->peerdn and we use that to detect double-calls.
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
+ state exim_gnutls_state_st *
-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
+peer_status(exim_gnutls_state_st *state)
{
-gnutls_session session;
+const gnutls_datum *cert_list;
+int rc;
+unsigned int cert_list_size = 0;
+gnutls_certificate_type_t ct;
+gnutls_x509_crt_t crt;
+uschar *dn_buf;
+size_t sz;
-gnutls_init(&session, side);
+if (state->peerdn)
+ return OK;
-/* Initialize the lists of permitted protocols, key-exchange methods, ciphers,
-and MACs. */
+state->peerdn = US"unknown";
-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));
+cert_list = gnutls_certificate_get_peers(state->session, &cert_list_size);
-/* The names OpenSSL uses in tls_require_ciphers are of the form DES-CBC3-SHA,
-using hyphen separators. GnuTLS uses underscore separators. So that I can use
-either form for tls_require_ciphers in my tests, and also for general
-convenience, we turn hyphens into underscores before scanning the list. */
+if (cert_list == NULL || cert_list_size == 0)
+ {
+ state->peerdn = US"unknown (no certificate)";
+ 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",
+ "no certificate received from peer", state->host);
+ return OK;
+ }
-if (expciphers != NULL)
+ct = gnutls_certificate_type_get(state->session);
+if (ct != GNUTLS_CRT_X509)
{
- uschar *s = expciphers;
- while (*s != 0) { if (*s == '-') *s = '_'; s++; }
+ const char *ctn = gnutls_certificate_type_get_name(ct);
+ state->peerdn = string_sprintf("unknown (type %s)", ctn);
+ 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);
+ return OK;
}
-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")))
+#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((Label), gnutls_strerror(rc), state->host); } \
+ return OK; } } while (0)
+
+rc = gnutls_x509_crt_init(&crt);
+exim_gnutls_peer_err(US"gnutls_x509_crt_init (crt)");
+
+rc = gnutls_x509_crt_import(crt, &cert_list[0], GNUTLS_X509_FMT_DER);
+exim_gnutls_peer_err(US"failed to import certificate [gnutls_x509_crt_import(cert 0)]");
+sz = 0;
+rc = gnutls_x509_crt_get_dn(crt, NULL, &sz);
+if (rc != GNUTLS_E_SHORT_MEMORY_BUFFER)
{
- gnutls_deinit(session);
- return NULL;
+ exim_gnutls_peer_err(US"getting size for cert DN failed");
+ return FAIL; /* should not happen */
}
+dn_buf = store_get_perm(sz);
+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
+}
-/* Define the various priorities */
-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);
-gnutls_cred_set(session, GNUTLS_CRD_CERTIFICATE, x509_cred);
-gnutls_dh_set_prime_bits(session, DH_BITS);
+/*************************************************
+* Verify peer certificate *
+*************************************************/
-/* Request or demand a certificate of the peer, as configured. This will
-happen only in a server. */
+/* 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.
-if (verify_requirement != VERIFY_NONE)
- gnutls_certificate_server_set_request(session,
- (verify_requirement == VERIFY_OPTIONAL)?
- GNUTLS_CERT_REQUEST : GNUTLS_CERT_REQUIRE);
+Arguments:
+ state exim_gnutls_state_st *
+ error where to put an error message
-gnutls_db_set_cache_expiration(session, ssl_session_timeout);
+Returns:
+ FALSE if the session should be rejected
+ TRUE if the cert is okay or we just don't care
+*/
-/* Reduce security in favour of increased compatibility, if the admin
-decides to make that trade-off. */
-if (gnutls_compat_mode)
+static BOOL
+verify_certificate(exim_gnutls_state_st *state, const char **error)
+{
+int rc;
+unsigned int verify;
+
+*error = NULL;
+
+rc = peer_status(state);
+if (rc != OK)
{
-#if LIBGNUTLS_VERSION_NUMBER >= 0x020104
- DEBUG(D_tls) debug_printf("lowering GnuTLS security, compatibility mode\n");
- gnutls_session_enable_compatibility_mode(session);
-#else
- DEBUG(D_tls) debug_printf("Unable to set gnutls_compat_mode - GnuTLS version too old\n");
-#endif
+ verify = GNUTLS_CERT_INVALID;
+ *error = "not supplied";
+ }
+else
+ {
+ rc = gnutls_certificate_verify_peers2(state->session, &verify);
}
-DEBUG(D_tls) debug_printf("initialized GnuTLS session\n");
-return session;
-}
+/* Handle the result of verification. INVALID seems to be set as well
+as REVOKED, but leave the test for both. */
+if ((rc < 0) || (verify & (GNUTLS_CERT_INVALID|GNUTLS_CERT_REVOKED)) != 0)
+ {
+ state->peer_cert_verified = FALSE;
+ if (*error == NULL)
+ *error = ((verify & GNUTLS_CERT_REVOKED) != 0) ? "revoked" : "invalid";
+ DEBUG(D_tls)
+ debug_printf("TLS certificate verification failed (%s): peerdn=%s\n",
+ *error, state->peerdn);
-/*************************************************
-* Get name of cipher in use *
-*************************************************/
+ if (state->verify_requirement == VERIFY_REQUIRED)
+ {
+ gnutls_alert_send(state->session, GNUTLS_AL_FATAL, GNUTLS_A_BAD_CERTIFICATE);
+ return FALSE;
+ }
+ DEBUG(D_tls)
+ debug_printf("TLS verify failure overriden (host in tls_try_verify_hosts)\n");
+ }
+else
+ {
+ state->peer_cert_verified = TRUE;
+ DEBUG(D_tls) debug_printf("TLS certificate verified: peerdn=%s\n", state->peerdn);
+ }
-/* The answer is left in a static buffer, and tls_cipher is set to point
-to it.
+tls_peerdn = state->peerdn;
-Argument: pointer to a GnuTLS session
-Returns: nothing
-*/
+return TRUE;
+}
+
+
+
+/* ------------------------------------------------------------------------ */
+/* Callbacks */
+
+/* Logging function which can be registered with
+ * gnutls_global_set_log_function()
+ * gnutls_global_set_log_level() 0..9
+ */
static void
-construct_cipher_name(gnutls_session session)
+exim_gnutls_logger_cb(int level, const char *message)
{
-static uschar cipherbuf[256];
-uschar *ver;
-int c, kx, mac;
-#ifdef GNUTLS_CB_TLS_UNIQUE
-int rc;
-gnutls_datum_t channel;
-#endif
+ DEBUG(D_tls) debug_printf("GnuTLS<%d>: %s\n", level, message);
+}
-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 */
-c = gnutls_cipher_get(session);
-/* returns size in "bytes" */
-tls_bits = gnutls_cipher_get_key_size(c) * 8;
+/* 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.
-mac = gnutls_mac_get(session);
-kx = gnutls_kx_get(session);
+Should be registered with
+ gnutls_handshake_set_post_client_hello_function()
-string_format(cipherbuf, sizeof(cipherbuf), "%s:%s:%u", ver,
- gnutls_cipher_suite_get_name(kx, c, mac), tls_bits);
-tls_cipher = cipherbuf;
+"This callback must return 0 on success or a gnutls error code to terminate the
+handshake.".
-DEBUG(D_tls) debug_printf("cipher: %s\n", cipherbuf);
+For inability to get SNI information, we return 0.
+We only return non-zero if re-setup failed.
+*/
-if (tls_channelbinding_b64)
- free(tls_channelbinding_b64);
-tls_channelbinding_b64 = NULL;
+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 = current_global_tls_state;
+unsigned int sni_type;
+int rc, old_pool;
+
+rc = gnutls_server_name_get(session, sni_name, &data_len, &sni_type, 0);
+exim_gnutls_err_debugreturn0("gnutls_server_name_get()");
+if (sni_type != GNUTLS_NAME_DNS)
+ {
+ DEBUG(D_tls) debug_printf("TLS: ignoring SNI of unhandled type %u\n", sni_type);
+ return 0;
+ }
-#ifdef GNUTLS_CB_TLS_UNIQUE
-channel = { NULL, 0 };
-rc = gnutls_session_channel_binding(session, GNUTLS_CB_TLS_UNIQUE, &channel);
-if (rc) {
- DEBUG(D_tls) debug_printf("Channel binding error: %s\n", gnutls_strerror(rc));
-} else {
- tls_channelbinding_b64 = auth_b64encode(channel.data, (int)channel.size);
- DEBUG(D_tls) debug_printf("Have channel bindings cached for possible auth usage.\n");
-}
-#endif
+/* We now have a UTF-8 string in sni_name */
+old_pool = store_pool;
+store_pool = POOL_PERM;
+state->received_sni = string_copyn(US sni_name, data_len);
+store_pool = old_pool;
+
+/* We set this one now so that variable expansions below will work */
+tls_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;
+
+rc = tls_expand_session_files(state);
+if (rc != 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 = gnutls_credentials_set(state->session, GNUTLS_CRD_CERTIFICATE, state->x509_cred);
+return (rc == GNUTLS_E_SUCCESS) ? 0 : rc;
}
+
+/* ------------------------------------------------------------------------ */
+/* Exported functions */
+
+
+
+
/*************************************************
* Start a TLS session in a server *
*************************************************/
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
*/
int
-tls_server_start(uschar *require_ciphers, uschar *require_mac,
- uschar *require_kx, uschar *require_proto)
+tls_server_start(const uschar *require_ciphers)
{
int rc;
const char *error;
-uschar *expciphers = NULL;
-uschar *expmac = NULL;
-uschar *expkx = NULL;
-uschar *expproto = NULL;
+exim_gnutls_state_st *state = NULL;
/* Check for previous activation */
+/* nb: this will not be TLS callout safe, needs reworking as part of that. */
if (tls_active >= 0)
{
- tls_error("STARTTLS received after TLS started", NULL, "");
+ tls_error(US"STARTTLS received after TLS started", "", NULL);
smtp_printf("554 Already in TLS\r\n");
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("initializing GnuTLS as a server\n");
+DEBUG(D_tls) debug_printf("initialising GnuTLS as a server\n");
-rc = tls_init(NULL, tls_certificate, tls_privatekey, tls_verify_certificates,
- tls_crl);
+rc = tls_init(NULL, tls_certificate, tls_privatekey,
+ NULL, tls_verify_certificates, tls_crl,
+ require_ciphers, &state);
if (rc != OK) return rc;
-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;
-
/* If this is a host for which certificate verification is mandatory or
optional, set up appropriately. */
-tls_certificate_verified = FALSE;
-verify_requirement = VERIFY_NONE;
-
if (verify_check_host(&tls_verify_hosts) == OK)
- verify_requirement = VERIFY_REQUIRED;
+ {
+ 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)
- verify_requirement = VERIFY_OPTIONAL;
+ {
+ 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);
+ }
-/* Prepare for new connection */
+/* Register SNI handling; always, even if not in tls_certificate, so that the
+expansion variable $tls_sni is always available. */
-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));
+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
/* Now negotiate the TLS session. We put our own timer on it, since it seems
that the GnuTLS library doesn't. */
-gnutls_transport_set_ptr2(tls_session, (gnutls_transport_ptr)fileno(smtp_in),
- (gnutls_transport_ptr)fileno(smtp_out));
+gnutls_transport_set_ptr2(state->session,
+ (gnutls_transport_ptr)fileno(smtp_in),
+ (gnutls_transport_ptr)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);
-rc = gnutls_handshake(tls_session);
+do
+ {
+ rc = gnutls_handshake(state->session);
+ } while ((rc == GNUTLS_E_AGAIN) || (rc == GNUTLS_E_INTERRUPTED));
alarm(0);
-if (rc < 0)
+if (rc != GNUTLS_E_SUCCESS)
{
- tls_error(US"gnutls_handshake", NULL,
- sigalrm_seen ? "timed out" : gnutls_strerror(rc));
-
+ tls_error(US"gnutls_handshake",
+ sigalrm_seen ? "timed out" : gnutls_strerror(rc), NULL);
/* It seems that, except in the case of a timeout, we have to close the
connection right here; otherwise if the other end is running OpenSSL it hangs
until the server times out. */
DEBUG(D_tls) debug_printf("gnutls_handshake was successful\n");
-if (verify_requirement != VERIFY_NONE &&
- !verify_certificate(tls_session, &error))
+/* Verify after the fact */
+
+if (state->verify_requirement != VERIFY_NONE)
{
- tls_error(US"certificate verification failed", NULL, error);
- return FAIL;
+ if (!verify_certificate(state, &error))
+ {
+ if (state->verify_requirement == VERIFY_OPTIONAL)
+ {
+ DEBUG(D_tls)
+ debug_printf("TLS: continuing on only because verification was optional, after: %s\n",
+ error);
+ }
+ else
+ {
+ tls_error(US"certificate verification failed", error, NULL);
+ return FAIL;
+ }
+ }
}
-construct_cipher_name(tls_session);
+/* Figure out peer DN, and if authenticated, etc. */
+
+rc = peer_status(state);
+if (rc != OK) return rc;
+
+/* 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. */
-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;
+state->xfer_buffer = store_malloc(ssl_xfer_buffer_size);
receive_getc = tls_getc;
receive_ungetc = tls_ungetc;
receive_ferror = tls_ferror;
receive_smtp_buffered = tls_smtp_buffered;
-tls_active = fileno(smtp_out);
-
return OK;
}
fd the fd of the connection
host connected host (for messages)
addr the first address (not used)
- dhparam DH parameter file
+ dhparam DH parameter file (ignored, we're a client)
certificate certificate file
privatekey private key file
sni TLS SNI to send to remote host
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),
*/
int
-tls_client_start(int fd, host_item *host, address_item *addr, uschar *dhparam,
- uschar *certificate, uschar *privatekey, uschar *sni ARG_UNUSED,
- uschar *verify_certs, uschar *verify_crl,
- uschar *require_ciphers, uschar *require_mac,
- uschar *require_kx, uschar *require_proto, int timeout)
+tls_client_start(int fd, host_item *host,
+ address_item *addr ARG_UNUSED, uschar *dhparam ARG_UNUSED,
+ uschar *certificate, uschar *privatekey, uschar *sni,
+ uschar *verify_certs, uschar *verify_crl,
+ uschar *require_ciphers, int timeout)
{
-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;
+const char *error;
+exim_gnutls_state_st *state = NULL;
-DEBUG(D_tls) debug_printf("initializing GnuTLS as a client\n");
+DEBUG(D_tls) debug_printf("initialising GnuTLS as a client on fd %d\n", fd);
-verify_requirement = (verify_certs == NULL)? VERIFY_NONE : VERIFY_REQUIRED;
-rc = tls_init(host, certificate, privatekey, verify_certs, verify_crl);
+rc = tls_init(host, certificate, privatekey,
+ sni, verify_certs, verify_crl, require_ciphers, &state);
if (rc != OK) return rc;
-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);
+gnutls_dh_set_prime_bits(state->session, EXIM_CLIENT_DH_MIN_BITS);
-if (tls_session == NULL)
- return tls_error(US "tls_session_init", host,
- gnutls_strerror(GNUTLS_E_MEMORY_ERROR));
+if (verify_certs == NULL)
+ {
+ DEBUG(D_tls) debug_printf("TLS: server certificate verification not required\n");
+ state->verify_requirement = VERIFY_NONE;
+ /* we still ask for it, to log it, etc */
+ gnutls_certificate_server_set_request(state->session, GNUTLS_CERT_REQUEST);
+ }
+else
+ {
+ 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);
+ }
-gnutls_transport_set_ptr(tls_session, (gnutls_transport_ptr)fd);
+gnutls_transport_set_ptr(state->session, (gnutls_transport_ptr)fd);
+state->fd_in = fd;
+state->fd_out = fd;
/* There doesn't seem to be a built-in timeout on connection. */
sigalrm_seen = FALSE;
alarm(timeout);
-rc = gnutls_handshake(tls_session);
+do
+ {
+ rc = gnutls_handshake(state->session);
+ } while ((rc == GNUTLS_E_AGAIN) || (rc == GNUTLS_E_INTERRUPTED));
alarm(0);
-if (rc < 0)
- return tls_error(US "gnutls_handshake", host,
- sigalrm_seen ? "timed out" : gnutls_strerror(rc));
+DEBUG(D_tls) debug_printf("gnutls_handshake was successful\n");
-server_certs = gnutls_certificate_get_peers(tls_session, &server_certs_size);
+/* Verify late */
-if (server_certs != NULL)
- {
- uschar buff[1024];
- gnutls_x509_crt gcert;
+if (state->verify_requirement != VERIFY_NONE &&
+ !verify_certificate(state, &error))
+ return tls_error(US"certificate verification failed", error, state->host);
- gnutls_x509_crt_init(&gcert);
- tls_peerdn = US"unknown";
+/* Figure out peer DN, and if authenticated, etc. */
- 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);
- }
- }
+rc = peer_status(state);
+if (rc != OK) return rc;
-/* Should we also verify the hostname here? */
+/* Sets various Exim expansion variables; always safe within server */
-if (verify_requirement != VERIFY_NONE &&
- !verify_certificate(tls_session, &error))
- return tls_error(US"certificate verification failed", host, error);
+extract_exim_vars_from_tls_state(state);
-construct_cipher_name(tls_session); /* Sets tls_cipher */
-tls_active = fd;
return OK;
}
+
/*************************************************
-* Deal with logging errors during I/O *
+* Close down a TLS session *
*************************************************/
-/* We have to get the identity of the peer from saved data.
-
-Argument:
- ec the GnuTLS error code, or 0 if it's a local error
- when text identifying read or write
- text local error text when ec is 0
+/* 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).
-Returns: nothing
+Arguments: TRUE if gnutls_bye is to be called
+Returns: nothing
*/
-static void
-record_io_error(int ec, uschar *when, uschar *text)
+void
+tls_close(BOOL shutdown)
{
-const char *msg;
+exim_gnutls_state_st *state = current_global_tls_state;
-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);
+if (tls_active < 0) return; /* TLS was not active */
+
+if (shutdown)
+ {
+ DEBUG(D_tls) debug_printf("tls_close(): shutting down TLS\n");
+ gnutls_bye(state->session, GNUTLS_SHUT_WR);
+ }
+
+gnutls_deinit(state->session);
+
+memcpy(state, &exim_gnutls_state_init, sizeof(exim_gnutls_state_init));
+
+if ((state_server.session == NULL) && (state_client.session == NULL))
+ {
+ gnutls_global_deinit();
+ exim_gnutls_base_init_done = FALSE;
+ }
-tls_error(when, client_host, msg);
+tls_active = -1;
}
+
/*************************************************
* 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.
+This feeds DKIM and should be used for all message-body reads.
+
Arguments: none
Returns: the next character or EOF
*/
int
tls_getc(void)
{
-if (ssl_xfer_buffer_lwm >= ssl_xfer_buffer_hwm)
+exim_gnutls_state_st *state = current_global_tls_state;
+if (state->xfer_buffer_lwm >= state->xfer_buffer_hwm)
{
- int inbytes;
+ ssize_t 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);
+ DEBUG(D_tls) debug_printf("Calling gnutls_record_recv(%p, %p, %u)\n",
+ state->session, state->xfer_buffer, ssl_xfer_buffer_size);
if (smtp_receive_timeout > 0) alarm(smtp_receive_timeout);
- inbytes = gnutls_record_recv(tls_session, CS ssl_xfer_buffer,
+ inbytes = gnutls_record_recv(state->session, state->xfer_buffer,
ssl_xfer_buffer_size);
alarm(0);
receive_ferror = smtp_ferror;
receive_smtp_buffered = smtp_buffered;
- gnutls_deinit(tls_session);
- tls_session = NULL;
+ gnutls_deinit(state->session);
+ state->session = NULL;
tls_active = -1;
+ tls_bits = 0;
+ tls_certificate_verified = FALSE;
+ tls_channelbinding_b64 = NULL;
tls_cipher = NULL;
tls_peerdn = NULL;
else if (inbytes < 0)
{
- record_io_error(inbytes, US"recv", NULL);
- ssl_xfer_error = 1;
+ record_io_error(state, (int) inbytes, US"recv", NULL);
+ state->xfer_error = 1;
return EOF;
}
#ifndef DISABLE_DKIM
- dkim_exim_verify_feed(ssl_xfer_buffer, inbytes);
+ dkim_exim_verify_feed(state->xfer_buffer, inbytes);
#endif
- ssl_xfer_buffer_hwm = inbytes;
- ssl_xfer_buffer_lwm = 0;
+ state->xfer_buffer_hwm = (int) inbytes;
+ state->xfer_buffer_lwm = 0;
}
-
/* Something in the buffer; return next uschar */
-return ssl_xfer_buffer[ssl_xfer_buffer_lwm++];
+return state->xfer_buffer[state->xfer_buffer_lwm++];
}
+
/*************************************************
* 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:
buff buffer of data
len size of buffer
int
tls_read(uschar *buff, size_t len)
{
-int inbytes;
+exim_gnutls_state_st *state = current_global_tls_state;
+ssize_t inbytes;
-DEBUG(D_tls) debug_printf("Calling gnutls_record_recv(%lx, %lx, %u)\n",
- (long) tls_session, (long) buff, len);
+if (len > INT_MAX)
+ len = INT_MAX;
-inbytes = gnutls_record_recv(tls_session, CS buff, len);
+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);
+
+inbytes = gnutls_record_recv(state->session, 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 record_io_error(state, (int)inbytes, US"recv", NULL);
return -1;
}
+
/*************************************************
* Write bytes down TLS channel *
*************************************************/
int
tls_write(const uschar *buff, size_t len)
{
-int outbytes;
-int left = len;
+ssize_t outbytes;
+size_t left = len;
+exim_gnutls_state_st *state = current_global_tls_state;
-DEBUG(D_tls) debug_printf("tls_do_write(%lx, %d)\n", (long) buff, left);
+DEBUG(D_tls) debug_printf("tls_do_write(%p, " SIZE_T_FMT ")\n", 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(SSL, %p, " SIZE_T_FMT ")\n",
+ buff, left);
+ outbytes = gnutls_record_send(state->session, buff, left);
- 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);
+ 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;
+ }
+
+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)
+int
+vaguely_random_number(int max)
{
-if (tls_active < 0) return; /* TLS was not active */
-
-if (shutdown)
+unsigned int r;
+int i, needed_len;
+uschar *p;
+uschar smallbuf[sizeof(r)];
+
+if (max <= 1)
+ return 0;
+
+needed_len = sizeof(r);
+/* Don't take 8 times more entropy than needed if int is 8 octets and we were
+ * asked for a number less than 10. */
+for (r = max, i = 0; r; ++i)
+ r >>= 1;
+i = (i + 7) / 8;
+if (i < needed_len)
+ needed_len = i;
+
+i = gnutls_rnd(GNUTLS_RND_NONCE, smallbuf, needed_len);
+if (i < 0)
{
- DEBUG(D_tls) debug_printf("tls_close(): shutting down TLS\n");
- gnutls_bye(tls_session, GNUTLS_SHUT_WR);
+ DEBUG(D_all) debug_printf("gnutls_rnd() failed, using fallback.\n");
+ return vaguely_random_number_fallback(max);
+ }
+r = 0;
+for (p = smallbuf; needed_len; --needed_len, ++p)
+ {
+ r *= 256;
+ r += *p;
}
-gnutls_deinit(tls_session);
-tls_session = NULL;
-gnutls_global_deinit();
-
-tls_active = -1;
+/* 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;
}
git://git.exim.org / exim.git / commitdiff