* Exim - an Internet mail transport agent *
*************************************************/
-/* Copyright (c) University of Cambridge 1995 - 2017 */
+/* Copyright (c) University of Cambridge 1995 - 2018 */
/* See the file NOTICE for conditions of use and distribution. */
/* Copyright (c) Phil Pennock 2012 */
# define SUPPORT_SRV_OCSP_STACK
#endif
+#ifdef SUPPORT_DANE
+# if GNUTLS_VERSION_NUMBER >= 0x030000
+# define DANESSL_USAGE_DANE_TA 2
+# define DANESSL_USAGE_DANE_EE 3
+# else
+# error GnuTLS version too early for DANE
+# endif
+# if GNUTLS_VERSION_NUMBER < 0x999999
+# define GNUTLS_BROKEN_DANE_VALIDATION
+# endif
+#endif
+
#ifndef DISABLE_OCSP
# include <gnutls/ocsp.h>
#endif
+#ifdef SUPPORT_DANE
+# include <gnutls/dane.h>
+#endif
/* GnuTLS 2 vs 3
/* Values for verify_requirement */
enum peer_verify_requirement
- { VERIFY_NONE, VERIFY_OPTIONAL, VERIFY_REQUIRED };
+ { VERIFY_NONE, VERIFY_OPTIONAL, VERIFY_REQUIRED, VERIFY_DANE };
/* 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
int fd_in;
int fd_out;
BOOL peer_cert_verified;
+ BOOL peer_dane_verified;
BOOL trigger_sni_changes;
BOOL have_set_peerdn;
const struct host_item *host;
#ifndef DISABLE_EVENT
uschar *event_action;
#endif
+#ifdef SUPPORT_DANE
+ char * const * dane_data;
+ const int * dane_data_len;
+#endif
tls_support *tlsp; /* set in tls_init() */
.fd_in = -1,
.fd_out = -1,
.peer_cert_verified = FALSE,
+ .peer_dane_verified = FALSE,
.trigger_sni_changes =FALSE,
.have_set_peerdn = FALSE,
.host = NULL,
DEBUG(D_tls) debug_printf("cipher: %s\n", state->ciphersuite);
tlsp->certificate_verified = state->peer_cert_verified;
+#ifdef SUPPORT_DANE
+tlsp->dane_verified = state->peer_dane_verified;
+#endif
/* note that tls_channelbinding_b64 is not saved to the spool file, since it's
only available for use for authenticators while this TLS session is running. */
the peer information, but that's too new for some OSes.
Arguments:
- state exim_gnutls_state_st *
- errstr where to put an error message
+ state exim_gnutls_state_st *
+ errstr where to put an error message
Returns:
FALSE if the session should be rejected
*/
static BOOL
-verify_certificate(exim_gnutls_state_st *state, uschar ** errstr)
+verify_certificate(exim_gnutls_state_st * state, uschar ** errstr)
{
int rc;
-unsigned int verify;
+uint verify;
+
+if (state->verify_requirement == VERIFY_NONE)
+ return TRUE;
*errstr = NULL;
*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 CA-chain-verification and 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 *));
+ ddl = store_get(nrec * sizeof(int));
+ 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;
+ }
+ state->peer_dane_verified = TRUE;
+
+# ifdef GNUTLS_BROKEN_DANE_VALIDATION
+ /* If a TA-mode TLSA record was used for verification we must additionally
+ verify the CA chain and the cert name. For EE-mode, skip it. */
+
+ if (usage & (1 << DANESSL_USAGE_DANE_EE))
+# endif
+ {
+ state->peer_cert_verified = TRUE;
+ goto goodcert;
+ }
+ }
+#endif
+
rc = gnutls_certificate_verify_peers2(state->session, &verify);
+ }
-/* Handle the result of verification. INVALID seems to be set as well
-as REVOKED, but leave the test for both. */
+/* Handle the result of verification. INVALID is set if any others are. */
-if (rc < 0 ||
- verify & (GNUTLS_CERT_INVALID|GNUTLS_CERT_REVOKED)
- )
+if (rc < 0 || verify & (GNUTLS_CERT_INVALID|GNUTLS_CERT_REVOKED))
{
state->peer_cert_verified = FALSE;
if (!*errstr)
*errstr, state->peerdn ? state->peerdn : US"<unset>");
if (state->verify_requirement >= VERIFY_REQUIRED)
- {
- gnutls_alert_send(state->session,
- GNUTLS_AL_FATAL, GNUTLS_A_BAD_CERTIFICATE);
- return FALSE;
- }
+ goto badcert;
DEBUG(D_tls)
debug_printf("TLS verify failure overridden (host in tls_try_verify_hosts)\n");
}
DEBUG(D_tls)
debug_printf("TLS certificate verification failed: cert name mismatch\n");
if (state->verify_requirement >= VERIFY_REQUIRED)
- {
- gnutls_alert_send(state->session,
- GNUTLS_AL_FATAL, GNUTLS_A_BAD_CERTIFICATE);
- return FALSE;
- }
+ goto badcert;
return TRUE;
}
}
state->peerdn ? state->peerdn : US"<unset>");
}
-state->tlsp->peerdn = state->peerdn;
+goodcert:
+ state->tlsp->peerdn = state->peerdn;
+ return TRUE;
-return TRUE;
+#ifdef SUPPORT_DANE
+tlsa_prob:
+ *errstr = string_sprintf("TLSA record problem: %s", dane_strerror(rc));
+#endif
+
+badcert:
+ gnutls_alert_send(state->session, GNUTLS_AL_FATAL, GNUTLS_A_BAD_CERTIFICATE);
+ return FALSE;
}
/* Verify after the fact */
-if ( state->verify_requirement != VERIFY_NONE
- && !verify_certificate(state, errstr))
+if (!verify_certificate(state, errstr))
{
if (state->verify_requirement != VERIFY_OPTIONAL)
{
}
+
+
+#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_record * rr;
+dns_scan dnss;
+int i;
+const char ** dane_data;
+int * dane_data_len;
+
+for (rr = dns_next_rr(dnsa, &dnss, RESET_ANSWERS), i = 1;
+ rr;
+ rr = dns_next_rr(dnsa, &dnss, RESET_NEXT)
+ ) if (rr->type == T_TLSA) i++;
+
+dane_data = store_get(i * sizeof(uschar *));
+dane_data_len = store_get(i * sizeof(int));
+
+for (rr = dns_next_rr(dnsa, &dnss, RESET_ANSWERS), i = 0;
+ rr;
+ rr = dns_next_rr(dnsa, &dnss, RESET_NEXT)
+ ) if (rr->type == T_TLSA)
+ {
+ const uschar * p = rr->data;
+ 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] = 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
+
+
+
/*************************************************
* Start a TLS session in a client *
*************************************************/
host connected host (for messages)
addr the first address (not used)
tb transport (always smtp)
-
+ tlsa_dnsa non-NULL, 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
errstr error string pointer
Returns: OK/DEFER/FAIL (because using common functions),
tls_client_start(int fd, host_item *host,
address_item *addr ARG_UNUSED,
transport_instance * tb,
-#ifdef EXPERIMENTAL_DANE
- dns_answer * tlsa_dnsa ARG_UNUSED,
+#ifdef SUPPORT_DANE
+ dns_answer * tlsa_dnsa,
#endif
uschar ** errstr)
{
smtp_transport_options_block *ob =
(smtp_transport_options_block *)tb->options_block;
int rc;
-exim_gnutls_state_st *state = NULL;
+exim_gnutls_state_st * state = NULL;
#ifndef DISABLE_OCSP
BOOL require_ocsp =
verify_check_given_host(&ob->hosts_require_ocsp, host) == OK;
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 */
-if ( ( state->exp_tls_verify_certificates
- && !ob->tls_verify_hosts
- && (!ob->tls_try_verify_hosts || !*ob->tls_try_verify_hosts)
- )
- || verify_check_given_host(&ob->tls_verify_hosts, host) == OK
- )
+#ifdef SUPPORT_DANE
+if (tlsa_dnsa && dane_tlsa_load(state, 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(&ob->tls_verify_hosts, host) == OK
+ )
{
tls_client_setup_hostname_checks(host, state, ob);
DEBUG(D_tls)
sigalrm_seen = FALSE;
alarm(ob->command_timeout);
do
- {
rc = gnutls_handshake(state->session);
- } while ((rc == GNUTLS_E_AGAIN) ||
- (rc == GNUTLS_E_INTERRUPTED && !sigalrm_seen));
+while (rc == GNUTLS_E_AGAIN || rc == GNUTLS_E_INTERRUPTED && !sigalrm_seen);
alarm(0);
if (rc != GNUTLS_E_SUCCESS)
/* Verify late */
-if (state->verify_requirement != VERIFY_NONE &&
- !verify_certificate(state, errstr))
+if (!verify_certificate(state, errstr))
return tls_error(US"certificate verification failed", *errstr, state->host, errstr);
#ifndef DISABLE_OCSP
state->tlsp->active = -1;
+if (state->xfer_buffer) store_free(state->xfer_buffer);
memcpy(state, &exim_gnutls_state_init, sizeof(exim_gnutls_state_init));
-if ((state_server.session == NULL) && (state_client.session == NULL))
+if (!state_server.session && !state_client.session)
{
gnutls_global_deinit();
exim_gnutls_base_init_done = FALSE;
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);
inbytes = gnutls_record_recv(state->session, state->xfer_buffer,
MIN(ssl_xfer_buffer_size, lim));
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