BUGFIX: forced-fail smtp option tls_sni would dereference NULL

[exim.git] / src / src / tls-gnu.c

diff --git a/src/src/tls-gnu.c b/src/src/tls-gnu.c
index c8bf634bc1ab26492de58225acade282bd4db900..c582af79f0c43472c434e6881c1ae9e666005fbc 100644 (file)
--- a/src/src/tls-gnu.c
+++ b/src/src/tls-gnu.c
@@ -63,8 +63,7 @@ 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.
 
 be set to point to content in one of these instances, as appropriate for
 the stage of the process lifetime.
 

-Not handled here: globals tls_active, tls_bits, tls_cipher, tls_peerdn,
-tls_certificate_verified, tls_channelbinding_b64, tls_sni.
+Not handled here: global tls_channelbinding_b64.

 */
 
 typedef struct exim_gnutls_state {
 */
 
 typedef struct exim_gnutls_state {


@@ -95,6 +94,8 @@ typedef struct exim_gnutls_state {
   uschar *exp_tls_crl;
   uschar *exp_tls_require_ciphers;
 
   uschar *exp_tls_crl;
   uschar *exp_tls_require_ciphers;
 

+  tls_support *tlsp;   /* set in tls_init() */
+

   uschar *xfer_buffer;
   int xfer_buffer_lwm;
   int xfer_buffer_hwm;
   uschar *xfer_buffer;
   int xfer_buffer_lwm;
   int xfer_buffer_hwm;


@@ -107,6 +108,7 @@ static const exim_gnutls_state_st exim_gnutls_state_init = {
   NULL, NULL, NULL, NULL,
   NULL, NULL, NULL, NULL, NULL, NULL,
   NULL, NULL, NULL, NULL, NULL, NULL,
   NULL, NULL, NULL, NULL,
   NULL, NULL, NULL, NULL, NULL, NULL,
   NULL, NULL, NULL, NULL, NULL, NULL,

+  NULL,

   NULL, 0, 0, 0, 0,
 };
 
   NULL, 0, 0, 0, 0,
 };
 


@@ -120,7 +122,6 @@ there's no way for heart-beats to be responded to, for the duration of the
 second connection. */
 
 static exim_gnutls_state_st state_server, state_client;
 second connection. */
 
 static exim_gnutls_state_st state_server, state_client;

-static exim_gnutls_state_st *current_global_tls_state;

 
 /* 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
 
 /* 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


@@ -286,15 +287,13 @@ Sets:
   tls_cipher                a string
   tls_peerdn                a string
   tls_sni                   a (UTF-8) string
   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
 
 Argument:
   state      the relevant exim_gnutls_state_st *
 */
 
 static void

-extract_exim_vars_from_tls_state(exim_gnutls_state_st *state)
+extract_exim_vars_from_tls_state(exim_gnutls_state_st *state, BOOL is_server)

 {
 gnutls_cipher_algorithm_t cipher;
 #ifdef HAVE_GNUTLS_SESSION_CHANNEL_BINDING
 {
 gnutls_cipher_algorithm_t cipher;
 #ifdef HAVE_GNUTLS_SESSION_CHANNEL_BINDING


@@ -303,19 +302,17 @@ int rc;
 gnutls_datum_t channel;
 #endif
 
 gnutls_datum_t channel;
 #endif
 

-current_global_tls_state = state;
-
-tls_active = state->fd_out;
+state->tlsp->active = state->fd_out;

 
 cipher = gnutls_cipher_get(state->session);
 /* returns size in "bytes" */
 
 cipher = gnutls_cipher_get(state->session);
 /* returns size in "bytes" */

-tls_bits = gnutls_cipher_get_key_size(cipher) * 8;
+state->tlsp->bits = gnutls_cipher_get_key_size(cipher) * 8;

 
 

-tls_cipher = state->ciphersuite;
+state->tlsp->cipher = state->ciphersuite;

 
 

-DEBUG(D_tls) debug_printf("cipher: %s\n", tls_cipher);
+DEBUG(D_tls) debug_printf("cipher: %s\n", state->ciphersuite);

 
 

-tls_certificate_verified = state->peer_cert_verified;
+state->tlsp->certificate_verified = state->peer_cert_verified;

 
 /* 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. */
 
 /* 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. */


@@ -336,9 +333,8 @@ if (rc) {
 }
 #endif
 
 }
 #endif
 

-tls_peerdn = state->peerdn;
-
-tls_sni = state->received_sni;
+state->tlsp->peerdn = state->peerdn;
+state->tlsp->sni =    state->received_sni;

 }
 
 
 }
 
 


@@ -653,7 +649,11 @@ if (!state->host)
   {
   if (!state->received_sni)
     {
   {
   if (!state->received_sni)
     {

-    if (state->tls_certificate && Ustrstr(state->tls_certificate, US"tls_sni"))
+    if (state->tls_certificate &&
+        (Ustrstr(state->tls_certificate, US"tls_sni") ||
+         Ustrstr(state->tls_certificate, US"tls_in_sni") ||
+         Ustrstr(state->tls_certificate, US"tls_out_sni")
+       ))

       {
       DEBUG(D_tls) debug_printf("We will re-expand TLS session files if we receive SNI.\n");
       state->trigger_sni_changes = TRUE;
       {
       DEBUG(D_tls) debug_printf("We will re-expand TLS session files if we receive SNI.\n");
       state->trigger_sni_changes = TRUE;


@@ -884,6 +884,7 @@ Arguments:
   cas             CA certs file
   crl             CRL file
   require_ciphers tls_require_ciphers setting
   cas             CA certs file
   crl             CRL file
   require_ciphers tls_require_ciphers setting

+  caller_state    returned state-info structure

 
 Returns:          OK/DEFER/FAIL
 */
 
 Returns:          OK/DEFER/FAIL
 */


@@ -929,6 +930,7 @@ if (host)
   {
   state = &state_client;
   memcpy(state, &exim_gnutls_state_init, sizeof(exim_gnutls_state_init));
   {
   state = &state_client;
   memcpy(state, &exim_gnutls_state_init, sizeof(exim_gnutls_state_init));

+  state->tlsp = &tls_out;

   DEBUG(D_tls) debug_printf("initialising GnuTLS client session\n");
   rc = gnutls_init(&state->session, GNUTLS_CLIENT);
   }
   DEBUG(D_tls) debug_printf("initialising GnuTLS client session\n");
   rc = gnutls_init(&state->session, GNUTLS_CLIENT);
   }


@@ -936,6 +938,7 @@ else
   {
   state = &state_server;
   memcpy(state, &exim_gnutls_state_init, sizeof(exim_gnutls_state_init));
   {
   state = &state_server;
   memcpy(state, &exim_gnutls_state_init, sizeof(exim_gnutls_state_init));

+  state->tlsp = &tls_in;

   DEBUG(D_tls) debug_printf("initialising GnuTLS server session\n");
   rc = gnutls_init(&state->session, GNUTLS_SERVER);
   }
   DEBUG(D_tls) debug_printf("initialising GnuTLS server session\n");
   rc = gnutls_init(&state->session, GNUTLS_SERVER);
   }


@@ -967,7 +970,7 @@ if (rc != OK) return rc;
 /* set SNI in client, only */
 if (host)
   {
 /* set SNI in client, only */
 if (host)
   {

-  if (!expand_check_tlsvar(tls_sni))
+  if (!expand_check(state->tlsp->sni, "tls_out_sni", &state->exp_tls_sni))

     return DEFER;
   if (state->exp_tls_sni && *state->exp_tls_sni)
     {
     return DEFER;
   if (state->exp_tls_sni && *state->exp_tls_sni)
     {


@@ -1038,8 +1041,6 @@ if (gnutls_compat_mode)
   }
 
 *caller_state = state;
   }
 
 *caller_state = state;

-/* needs to happen before callbacks during handshake */
-current_global_tls_state = state;

 return OK;
 }
 
 return OK;
 }
 


@@ -1118,7 +1119,7 @@ old_pool = store_pool;
 store_pool = POOL_PERM;
 state->ciphersuite = string_copy(cipherbuf);
 store_pool = old_pool;
 store_pool = POOL_PERM;
 state->ciphersuite = string_copy(cipherbuf);
 store_pool = old_pool;

-tls_cipher = state->ciphersuite;
+state->tlsp->cipher = state->ciphersuite;

 
 /* tls_peerdn */
 cert_list = gnutls_certificate_get_peers(state->session, &cert_list_size);
 
 /* tls_peerdn */
 cert_list = gnutls_certificate_get_peers(state->session, &cert_list_size);


@@ -1240,7 +1241,7 @@ else
       state->peerdn ? state->peerdn : US"<unset>");
   }
 
       state->peerdn ? state->peerdn : US"<unset>");
   }
 

-tls_peerdn = state->peerdn;
+state->tlsp->peerdn = state->peerdn;

 
 return TRUE;
 }
 
 return TRUE;
 }


@@ -1284,6 +1285,7 @@ handshake.".
 
 For inability to get SNI information, we return 0.
 We only return non-zero if re-setup failed.
 
 For inability to get SNI information, we return 0.
 We only return non-zero if re-setup failed.

+Only used for server-side TLS.

 */
 
 static int
 */
 
 static int


@@ -1291,7 +1293,7 @@ exim_sni_handling_cb(gnutls_session_t session)
 {
 char sni_name[MAX_HOST_LEN];
 size_t data_len = MAX_HOST_LEN;
 {
 char sni_name[MAX_HOST_LEN];
 size_t data_len = MAX_HOST_LEN;

-exim_gnutls_state_st *state = current_global_tls_state;
+exim_gnutls_state_st *state = &state_server;

 unsigned int sni_type;
 int rc, old_pool;
 
 unsigned int sni_type;
 int rc, old_pool;
 


@@ -1321,7 +1323,7 @@ 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 */
 store_pool = old_pool;
 
 /* We set this one now so that variable expansions below will work */

-tls_sni = state->received_sni;
+state->tlsp->sni = state->received_sni;

 
 DEBUG(D_tls) debug_printf("Received TLS SNI \"%s\"%s\n", sni_name,
     state->trigger_sni_changes ? "" : " (unused for certificate selection)");
 
 DEBUG(D_tls) debug_printf("Received TLS SNI \"%s\"%s\n", sni_name,
     state->trigger_sni_changes ? "" : " (unused for certificate selection)");


@@ -1377,9 +1379,7 @@ const char *error;
 exim_gnutls_state_st *state = NULL;
 
 /* Check for previous activation */
 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)
+if (tls_in.active >= 0)

   {
   tls_error(US"STARTTLS received after TLS started", "", NULL);
   smtp_printf("554 Already in TLS\r\n");
   {
   tls_error(US"STARTTLS received after TLS started", "", NULL);
   smtp_printf("554 Already in TLS\r\n");


@@ -1430,10 +1430,10 @@ make them disconnect. We need to have an explicit fflush() here, to force out
 the response. Other smtp_printf() calls do not need it, because in non-TLS
 mode, the fflush() happens when smtp_getc() is called. */
 
 the response. Other smtp_printf() calls do not need it, because in non-TLS
 mode, the fflush() happens when smtp_getc() is called. */
 

-if (!tls_on_connect)
+if (!state->tlsp->on_connect)

   {
   smtp_printf("220 TLS go ahead\r\n");
   {
   smtp_printf("220 TLS go ahead\r\n");

-  fflush(smtp_out);
+  fflush(smtp_out);            /*XXX JGH */

   }
 
 /* Now negotiate the TLS session. We put our own timer on it, since it seems
   }
 
 /* Now negotiate the TLS session. We put our own timer on it, since it seems


@@ -1500,7 +1500,7 @@ if (rc != OK) return rc;
 
 /* Sets various Exim expansion variables; always safe within server */
 
 
 /* Sets various Exim expansion variables; always safe within server */
 

-extract_exim_vars_from_tls_state(state);
+extract_exim_vars_from_tls_state(state, TRUE);

 
 /* TLS has been set up. Adjust the input functions to read via TLS,
 and initialize appropriately. */
 
 /* TLS has been set up. Adjust the input functions to read via TLS,
 and initialize appropriately. */


@@ -1536,6 +1536,7 @@ Arguments:
   verify_certs      file for certificate verify
   verify_crl        CRL for verify
   require_ciphers   list of allowed ciphers or NULL
   verify_certs      file for certificate verify
   verify_crl        CRL for verify
   require_ciphers   list of allowed ciphers or NULL

+  dh_min_bits       minimum number of bits acceptable in server's DH prime

   timeout           startup timeout
 
 Returns:            OK/DEFER/FAIL (because using common functions),
   timeout           startup timeout
 
 Returns:            OK/DEFER/FAIL (because using common functions),


@@ -1547,7 +1548,7 @@ 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,
     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)
+    uschar *require_ciphers, int dh_min_bits, int timeout)

 {
 int rc;
 const char *error;
 {
 int rc;
 const char *error;


@@ -1559,7 +1560,17 @@ rc = tls_init(host, certificate, privatekey,
     sni, verify_certs, verify_crl, require_ciphers, &state);
 if (rc != OK) return rc;
 
     sni, verify_certs, verify_crl, require_ciphers, &state);
 if (rc != OK) return rc;
 

-gnutls_dh_set_prime_bits(state->session, EXIM_CLIENT_DH_MIN_BITS);
+if (dh_min_bits < EXIM_CLIENT_DH_MIN_MIN_BITS)
+  {
+  DEBUG(D_tls)
+    debug_printf("WARNING: tls_dh_min_bits far too low, clamping %d up to %d\n",
+        dh_min_bits, EXIM_CLIENT_DH_MIN_MIN_BITS);
+  dh_min_bits = EXIM_CLIENT_DH_MIN_MIN_BITS;
+  }
+
+DEBUG(D_tls) debug_printf("Setting D-H prime minimum acceptable bits to %d\n",
+    dh_min_bits);
+gnutls_dh_set_prime_bits(state->session, dh_min_bits);

 
 if (verify_certs == NULL)
   {
 
 if (verify_certs == NULL)
   {


@@ -1609,7 +1620,7 @@ if (rc != OK) return rc;
 
 /* Sets various Exim expansion variables; may need to adjust for ACL callouts */
 
 
 /* Sets various Exim expansion variables; may need to adjust for ACL callouts */
 

-extract_exim_vars_from_tls_state(state);
+extract_exim_vars_from_tls_state(state, FALSE);

 
 return OK;
 }
 
 return OK;
 }


@@ -1630,11 +1641,11 @@ Returns:     nothing
 */
 
 void
 */
 
 void

-tls_close(BOOL shutdown)
+tls_close(BOOL is_server, BOOL shutdown)

 {
 {

-exim_gnutls_state_st *state = current_global_tls_state;
+exim_gnutls_state_st *state = is_server ? &state_server : &state_client;

 
 

-if (tls_active < 0) return;  /* TLS was not active */
+if (!state->tlsp || state->tlsp->active < 0) return;  /* TLS was not active */

 
 if (shutdown)
   {
 
 if (shutdown)
   {


@@ -1644,6 +1655,7 @@ if (shutdown)
 
 gnutls_deinit(state->session);
 
 
 gnutls_deinit(state->session);
 

+state->tlsp->active = -1;

 memcpy(state, &exim_gnutls_state_init, sizeof(exim_gnutls_state_init));
 
 if ((state_server.session == NULL) && (state_client.session == NULL))
 memcpy(state, &exim_gnutls_state_init, sizeof(exim_gnutls_state_init));
 
 if ((state_server.session == NULL) && (state_client.session == NULL))


@@ -1652,7 +1664,6 @@ if ((state_server.session == NULL) && (state_client.session == NULL))
   exim_gnutls_base_init_done = FALSE;
   }
 
   exim_gnutls_base_init_done = FALSE;
   }
 

-tls_active = -1;

 }
 
 
 }
 
 


@@ -1664,6 +1675,7 @@ tls_active = -1;
 
 /* 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 gets the next byte from the TLS input buffer. If the buffer is empty,
 it refills the buffer via the GnuTLS reading function.

+Only used by the server-side TLS.

 
 This feeds DKIM and should be used for all message-body reads.
 
 
 This feeds DKIM and should be used for all message-body reads.
 


@@ -1674,7 +1686,7 @@ Returns:    the next character or EOF
 int
 tls_getc(void)
 {
 int
 tls_getc(void)
 {

-exim_gnutls_state_st *state = current_global_tls_state;
+exim_gnutls_state_st *state = &state_server;

 if (state->xfer_buffer_lwm >= state->xfer_buffer_hwm)
   {
   ssize_t inbytes;
 if (state->xfer_buffer_lwm >= state->xfer_buffer_hwm)
   {
   ssize_t inbytes;


@@ -1703,12 +1715,12 @@ if (state->xfer_buffer_lwm >= state->xfer_buffer_hwm)
 
     gnutls_deinit(state->session);
     state->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;
+    state->tlsp->active = -1;
+    state->tlsp->bits = 0;
+    state->tlsp->certificate_verified = FALSE;
+    tls_channelbinding_b64 = NULL;     /*XXX JGH */
+    state->tlsp->cipher = NULL;
+    state->tlsp->peerdn = NULL;

 
     return smtp_getc();
     }
 
     return smtp_getc();
     }


@@ -1742,6 +1754,7 @@ return state->xfer_buffer[state->xfer_buffer_lwm++];
 
 /* This does not feed DKIM, so if the caller uses this for reading message body,
 then the caller must feed DKIM.
 
 /* 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
 Arguments:
   buff      buffer of data
   len       size of buffer


@@ -1751,9 +1764,9 @@ Returns:    the number of bytes read
 */
 
 int
 */
 
 int

-tls_read(uschar *buff, size_t len)
+tls_read(BOOL is_server, uschar *buff, size_t len)

 {
 {

-exim_gnutls_state_st *state = current_global_tls_state;
+exim_gnutls_state_st *state = is_server ? &state_server : &state_client;

 ssize_t inbytes;
 
 if (len > INT_MAX)
 ssize_t inbytes;
 
 if (len > INT_MAX)


@@ -1789,6 +1802,7 @@ return -1;
 
 /*
 Arguments:
 
 /*
 Arguments:

+  is_server channel specifier

   buff      buffer of data
   len       number of bytes
 
   buff      buffer of data
   len       number of bytes
 


@@ -1797,11 +1811,11 @@ Returns:    the number of bytes after a successful write,
 */
 
 int
 */
 
 int

-tls_write(const uschar *buff, size_t len)
+tls_write(BOOL is_server, const uschar *buff, size_t len)

 {
 ssize_t outbytes;
 size_t left = len;
 {
 ssize_t outbytes;
 size_t left = len;

-exim_gnutls_state_st *state = current_global_tls_state;
+exim_gnutls_state_st *state = is_server ? &state_server : &state_client;

 
 DEBUG(D_tls) debug_printf("tls_do_write(%p, " SIZE_T_FMT ")\n", buff, left);
 while (left > 0)
 
 DEBUG(D_tls) debug_printf("tls_do_write(%p, " SIZE_T_FMT ")\n", buff, left);
 while (left > 0)