#ifndef DISABLE_OCSP
# include <openssl/ocsp.h>
#endif
+#ifdef EXPERIMENTAL_DANE
+# include <danessl.h>
+#endif
+
#ifndef DISABLE_OCSP
# define EXIM_OCSP_SKEW_SECONDS (300L)
}
+#ifdef EXPERIMENTAL_DANE
+
+/* This gets called *by* the dane library verify callback, which interposes
+itself.
+*/
+static int
+verify_callback_client_dane(int state, X509_STORE_CTX * x509ctx)
+{
+X509 * cert = X509_STORE_CTX_get_current_cert(x509ctx);
+static uschar txt[256];
+
+X509_NAME_oneline(X509_get_subject_name(cert), CS txt, sizeof(txt));
+
+DEBUG(D_tls) debug_printf("verify_callback_client_dane: %s\n", txt);
+tls_out.peerdn = txt;
+tls_out.peercert = X509_dup(cert);
+
+if (state == 1)
+ tls_out.dane_verified =
+ tls_out.certificate_verified = TRUE;
+return 1;
+}
+
+#endif /*EXPERIMENTAL_DANE*/
+
/*************************************************
* Information callback *
#endif /*!DISABLE_OCSP*/
-
/*************************************************
* Initialize for TLS *
*************************************************/
of the library. We allocate and return a context structure.
Arguments:
+ ctxp returned SSL context
host connected host, if client; NULL if server
dhparam DH parameter file
certificate certificate file
privatekey private key
ocsp_file file of stapling info (server); flag for require ocsp (client)
addr address if client; NULL if server (for some randomness)
- cbp place to put allocated context
+ cbp place to put allocated callback context
Returns: OK/DEFER/FAIL
*/
optional, set up appropriately. */
tls_in.certificate_verified = FALSE;
+#ifdef EXPERIMENTAL_DANE
+tls_in.dane_verified = FALSE;
+#endif
server_verify_callback_called = FALSE;
if (verify_check_host(&tls_verify_hosts) == OK)
+static int
+tls_client_basic_ctx_init(SSL_CTX * ctx,
+ host_item * host, smtp_transport_options_block * ob
+#ifdef EXPERIMENTAL_CERTNAMES
+ , tls_ext_ctx_cb * cbinfo
+#endif
+ )
+{
+int rc;
+/* stick to the old behaviour for compatibility if tls_verify_certificates is
+ set but both tls_verify_hosts and tls_try_verify_hosts is not set. Check only
+ the specified host patterns if one of them is defined */
+
+if ((!ob->tls_verify_hosts && !ob->tls_try_verify_hosts) ||
+ (verify_check_host(&ob->tls_verify_hosts) == OK))
+ {
+ if ((rc = setup_certs(ctx, ob->tls_verify_certificates,
+ ob->tls_crl, host, FALSE, verify_callback_client)) != OK)
+ return rc;
+ client_verify_optional = FALSE;
+
+#ifdef EXPERIMENTAL_CERTNAMES
+ if (ob->tls_verify_cert_hostnames)
+ {
+ if (!expand_check(ob->tls_verify_cert_hostnames,
+ US"tls_verify_cert_hostnames",
+ &cbinfo->verify_cert_hostnames))
+ return FAIL;
+ if (cbinfo->verify_cert_hostnames)
+ DEBUG(D_tls) debug_printf("Cert hostname to check: \"%s\"\n",
+ cbinfo->verify_cert_hostnames);
+ }
+#endif
+ }
+else if (verify_check_host(&ob->tls_try_verify_hosts) == OK)
+ {
+ if ((rc = setup_certs(ctx, ob->tls_verify_certificates,
+ ob->tls_crl, host, TRUE, verify_callback_client)) != OK)
+ return rc;
+ client_verify_optional = TRUE;
+ }
+
+return OK;
+}
+
+
+#ifdef EXPERIMENTAL_DANE
+static int
+tlsa_lookup(host_item * host, dns_answer * dnsa,
+ BOOL dane_required, BOOL * dane)
+{
+/* move this out to host.c given the similarity to dns_lookup() ? */
+uschar buffer[300];
+uschar * fullname = buffer;
+
+/* TLSA lookup string */
+(void)sprintf(CS buffer, "_%d._tcp.%.256s", host->port, host->name);
+
+switch (dns_lookup(dnsa, buffer, T_TLSA, &fullname))
+ {
+ case DNS_AGAIN:
+ return DEFER; /* just defer this TLS'd conn */
+
+ default:
+ case DNS_FAIL:
+ if (dane_required)
+ {
+ log_write(0, LOG_MAIN, "DANE error: TLSA lookup failed");
+ return FAIL;
+ }
+ break;
+
+ case DNS_SUCCEED:
+ if (!dns_is_secure(dnsa))
+ {
+ log_write(0, LOG_MAIN, "DANE error: TLSA lookup not DNSSEC");
+ return DEFER;
+ }
+ *dane = TRUE;
+ break;
+ }
+return OK;
+}
+
+
+static int
+dane_tlsa_load(SSL * ssl, host_item * host, dns_answer * dnsa)
+{
+dns_record * rr;
+dns_scan dnss;
+const char * hostnames[2] = { CS host->name, NULL };
+int found = 0;
+
+if (DANESSL_init(ssl, NULL, hostnames) != 1)
+ return tls_error(US"hostnames load", host, NULL);
+
+for (rr = dns_next_rr(dnsa, &dnss, RESET_ANSWERS);
+ rr;
+ rr = dns_next_rr(dnsa, &dnss, RESET_NEXT)
+ ) if (rr->type == T_TLSA)
+ {
+ uschar * p = rr->data;
+ uint8_t usage, selector, mtype;
+ const char * mdname;
+
+ found++;
+ usage = *p++;
+ selector = *p++;
+ mtype = *p++;
+
+ switch (mtype)
+ {
+ default:
+ log_write(0, LOG_MAIN,
+ "DANE error: TLSA record w/bad mtype 0x%x", mtype);
+ return FAIL;
+ case 0: mdname = NULL; break;
+ case 1: mdname = "sha256"; break;
+ case 2: mdname = "sha512"; break;
+ }
+
+ switch (DANESSL_add_tlsa(ssl, usage, selector, mdname, p, rr->size - 3))
+ {
+ default:
+ case 0: /* action not taken */
+ return tls_error(US"tlsa load", host, NULL);
+ case 1: break;
+ }
+
+ tls_out.tlsa_usage |= 1<<usage;
+ }
+
+if (found)
+ return OK;
+
+log_write(0, LOG_MAIN, "DANE error: No TLSA records");
+return FAIL;
+}
+#endif /*EXPERIMENTAL_DANE*/
+
+
/*************************************************
* Start a TLS session in a client *
smtp_transport_options_block * ob =
(smtp_transport_options_block *)tb->options_block;
static uschar txt[256];
-uschar *expciphers;
-X509* server_cert;
+uschar * expciphers;
+X509 * server_cert;
int rc;
static uschar cipherbuf[256];
+
#ifndef DISABLE_OCSP
-BOOL require_ocsp = verify_check_this_host(&ob->hosts_require_ocsp,
- NULL, host->name, host->address, NULL) == OK;
-BOOL request_ocsp = require_ocsp ? TRUE
- : verify_check_this_host(&ob->hosts_request_ocsp,
- NULL, host->name, host->address, NULL) == OK;
+BOOL request_ocsp = FALSE;
+BOOL require_ocsp = FALSE;
+#endif
+#ifdef EXPERIMENTAL_DANE
+dns_answer tlsa_dnsa;
+BOOL dane = FALSE;
+BOOL dane_required;
+#endif
+
+#ifdef EXPERIMENTAL_DANE
+tls_out.dane_verified = FALSE;
+tls_out.tlsa_usage = 0;
+dane_required = verify_check_this_host(&ob->hosts_require_dane, NULL,
+ host->name, host->address, NULL) == OK;
+
+if (host->dnssec == DS_YES)
+ {
+ if( dane_required
+ || verify_check_this_host(&ob->hosts_try_dane, NULL,
+ host->name, host->address, NULL) == OK
+ )
+ if ((rc = tlsa_lookup(host, &tlsa_dnsa, dane_required, &dane)) != OK)
+ return rc;
+ }
+else if (dane_required)
+ {
+ /*XXX a shame we only find this after making tcp & smtp connection */
+ /* move the test earlier? */
+ log_write(0, LOG_MAIN, "DANE error: previous lookup not DNSSEC");
+ return FAIL;
+ }
+#endif
+
+#ifndef DISABLE_OCSP
+ {
+ if ((require_ocsp = verify_check_this_host(&ob->hosts_require_ocsp,
+ NULL, host->name, host->address, NULL) == OK))
+ request_ocsp = TRUE;
+ else
+ {
+# ifdef EXPERIMENTAL_DANE
+ if ( dane
+ && ob->hosts_request_ocsp[0] == '*'
+ && ob->hosts_request_ocsp[1] == '\0'
+ )
+ {
+ /* Unchanged from default. Use a safer one under DANE */
+ request_ocsp = TRUE;
+ ob->hosts_request_ocsp = US"${if or { {= {0}{$tls_out_tlsa_usage}} "
+ " {= {4}{$tls_out_tlsa_usage}} } "
+ " {*}{}}";
+ }
+ else
+# endif
+ request_ocsp = verify_check_this_host(&ob->hosts_request_ocsp,
+ NULL, host->name, host->address, NULL) == OK;
+ }
+ }
#endif
rc = tls_init(&client_ctx, host, NULL,
return tls_error(US"SSL_CTX_set_cipher_list", host, NULL);
}
-/* stick to the old behaviour for compatibility if tls_verify_certificates is
- set but both tls_verify_hosts and tls_try_verify_hosts is not set. Check only
- the specified host patterns if one of them is defined */
-
-if ((!ob->tls_verify_hosts && !ob->tls_try_verify_hosts) ||
- (verify_check_host(&ob->tls_verify_hosts) == OK))
+#ifdef EXPERIMENTAL_DANE
+if (dane)
{
- if ((rc = setup_certs(client_ctx, ob->tls_verify_certificates,
- ob->tls_crl, host, FALSE, verify_callback_client)) != OK)
- return rc;
- client_verify_optional = FALSE;
+ SSL_CTX_set_verify(client_ctx, SSL_VERIFY_PEER, verify_callback_client_dane);
+
+ if (!DANESSL_library_init())
+ return tls_error(US"library init", host, NULL);
+ if (DANESSL_CTX_init(client_ctx) <= 0)
+ return tls_error(US"context init", host, NULL);
+ }
+else
+#endif
+
+ if ((rc = tls_client_basic_ctx_init(client_ctx, host, ob
#ifdef EXPERIMENTAL_CERTNAMES
- if (ob->tls_verify_cert_hostnames)
- {
- if (!expand_check(ob->tls_verify_cert_hostnames,
- US"tls_verify_cert_hostnames",
- &client_static_cbinfo->verify_cert_hostnames))
- return FAIL;
- if (client_static_cbinfo->verify_cert_hostnames)
- DEBUG(D_tls) debug_printf("Cert hostname to check: \"%s\"\n",
- client_static_cbinfo->verify_cert_hostnames);
- }
+ , client_static_cbinfo
#endif
- }
-else if (verify_check_host(&ob->tls_try_verify_hosts) == OK)
- {
- if ((rc = setup_certs(client_ctx, ob->tls_verify_certificates,
- ob->tls_crl, host, TRUE, verify_callback_client)) != OK)
+ )) != OK)
return rc;
- client_verify_optional = TRUE;
- }
if ((client_ssl = SSL_new(client_ctx)) == NULL)
return tls_error(US"SSL_new", host, NULL);
}
}
+#ifdef EXPERIMENTAL_DANE
+if (dane)
+ if ((rc = dane_tlsa_load(client_ssl, host, &tlsa_dnsa)) != OK)
+ return rc;
+#endif
+
#ifndef DISABLE_OCSP
/* Request certificate status at connection-time. If the server
does OCSP stapling we will get the callback (set in tls_init()) */
+# ifdef EXPERIMENTAL_DANE
+if (request_ocsp)
+ {
+ const uschar * s;
+ if ( (s = ob->hosts_require_ocsp) && Ustrstr(s, US"tls_out_tlsa_usage")
+ || (s = ob->hosts_request_ocsp) && Ustrstr(s, US"tls_out_tlsa_usage")
+ )
+ { /* Re-eval now $tls_out_tlsa_usage is populated. If
+ this means we avoid the OCSP request, we wasted the setup
+ cost in tls_init(). */
+ require_ocsp = verify_check_this_host(&ob->hosts_require_ocsp,
+ NULL, host->name, host->address, NULL) == OK;
+ request_ocsp = require_ocsp ? TRUE
+ : verify_check_this_host(&ob->hosts_request_ocsp,
+ NULL, host->name, host->address, NULL) == OK;
+ }
+ }
+# endif
+
if (request_ocsp)
{
SSL_set_tlsext_status_type(client_ssl, TLSEXT_STATUSTYPE_ocsp);
rc = SSL_connect(client_ssl);
alarm(0);
+#ifdef EXPERIMENTAL_DANE
+if (dane)
+ DANESSL_cleanup(client_ssl);
+#endif
+
if (rc <= 0)
return tls_error(US"SSL_connect", host, sigalrm_seen ? US"timed out" : NULL);
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