Merge pull request from GHSA-cv8x-p47p-99wr

* - Avoid SSL socket parent/listener getting destroyed during handshake by increasing parent's reference count. - Add missing SSL socket close when the newly accepted SSL socket is discarded in SIP TLS transport. * - Fix silly mistake: accepted active socket created without group lock in SSL socket. - Replace assertion with normal validation check of SSL socket instance in OpenSSL verification callback (verify_cb()) to avoid crash, e.g: if somehow race condition with SSL socket destroy happens or OpenSSL application data index somehow gets corrupted.
pjsip · Jul 23, 2021 · b8e4403 · b8e4403
1 parent 842b4ba
commit b8e4403
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Showing 3 changed files with 95 additions and 20 deletions.
diff --git a/pjlib/src/pj/ssl_sock_imp_common.c b/pjlib/src/pj/ssl_sock_imp_common.c
@@ -255,6 +255,8 @@ static pj_bool_t on_handshake_complete(pj_ssl_sock_t *ssock,
 
     /* Accepting */
     if (ssock->is_server) {
+	pj_bool_t ret = PJ_TRUE;
+
 	if (status != PJ_SUCCESS) {
 	    /* Handshake failed in accepting, destroy our self silently. */
 
@@ -272,6 +274,12 @@ static pj_bool_t on_handshake_complete(pj_ssl_sock_t *ssock,
 		      status);
 	    }
 
+	    /* Decrement ref count of parent */
+	    if (ssock->parent->param.grp_lock) {
+		pj_grp_lock_dec_ref(ssock->parent->param.grp_lock);
+		ssock->parent = NULL;
+	    }
+
 	    /* Originally, this is a workaround for ticket #985. However,
 	     * a race condition may occur in multiple worker threads
 	     * environment when we are destroying SSL objects while other
@@ -315,23 +323,29 @@ static pj_bool_t on_handshake_complete(pj_ssl_sock_t *ssock,
 
 	    return PJ_FALSE;
 	}
+
 	/* Notify application the newly accepted SSL socket */
 	if (ssock->param.cb.on_accept_complete2) {
-	    pj_bool_t ret;
 	    ret = (*ssock->param.cb.on_accept_complete2) 
 		    (ssock->parent, ssock, (pj_sockaddr_t*)&ssock->rem_addr, 
 		    pj_sockaddr_get_len((pj_sockaddr_t*)&ssock->rem_addr), 
 		    status);
-	    if (ret == PJ_FALSE)
-		return PJ_FALSE;	
 	} else if (ssock->param.cb.on_accept_complete) {
-	    pj_bool_t ret;
 	    ret = (*ssock->param.cb.on_accept_complete)
 		      (ssock->parent, ssock, (pj_sockaddr_t*)&ssock->rem_addr,
 		       pj_sockaddr_get_len((pj_sockaddr_t*)&ssock->rem_addr));
-	    if (ret == PJ_FALSE)
-		return PJ_FALSE;
 	}
+
+	/* Decrement ref count of parent and reset parent (we don't need it
+	 * anymore, right?).
+	 */
+	if (ssock->parent->param.grp_lock) {
+	    pj_grp_lock_dec_ref(ssock->parent->param.grp_lock);
+	    ssock->parent = NULL;
+	}
+
+	if (ret == PJ_FALSE)
+	    return PJ_FALSE;
     }
 
     /* Connecting */
@@ -930,9 +944,13 @@ static pj_bool_t ssock_on_accept_complete (pj_ssl_sock_t *ssock_parent,
     if (status != PJ_SUCCESS)
 	goto on_return;
 
+    /* Set parent and add ref count (avoid parent destroy during handshake) */
+    ssock->parent = ssock_parent;
+    if (ssock->parent->param.grp_lock)
+	pj_grp_lock_add_ref(ssock->parent->param.grp_lock);
+
     /* Update new SSL socket attributes */
     ssock->sock = newsock;
-    ssock->parent = ssock_parent;
     ssock->is_server = PJ_TRUE;
     if (ssock_parent->cert) {
 	status = pj_ssl_sock_set_certificate(ssock, ssock->pool, 
@@ -957,16 +975,20 @@ static pj_bool_t ssock_on_accept_complete (pj_ssl_sock_t *ssock_parent,
     ssock->asock_rbuf = (void**)pj_pool_calloc(ssock->pool, 
 					       ssock->param.async_cnt,
 					       sizeof(void*));
-    if (!ssock->asock_rbuf)
-        return PJ_ENOMEM;
+    if (!ssock->asock_rbuf) {
+	status = PJ_ENOMEM;
+	goto on_return;
+    }
 
     for (i = 0; i<ssock->param.async_cnt; ++i) {
 	ssock->asock_rbuf[i] = (void*) pj_pool_alloc(
 					    ssock->pool, 
 					    ssock->param.read_buffer_size + 
 					    sizeof(read_data_t*));
-        if (!ssock->asock_rbuf[i])
-            return PJ_ENOMEM;
+	if (!ssock->asock_rbuf[i]) {
+	    status = PJ_ENOMEM;
+	    goto on_return;
+	}
     }
 
     /* If listener socket has group lock, automatically create group lock
@@ -980,7 +1002,7 @@ static pj_bool_t ssock_on_accept_complete (pj_ssl_sock_t *ssock_parent,
 	    goto on_return;
 
 	pj_grp_lock_add_ref(glock);
-	asock_cfg.grp_lock = ssock->param.grp_lock = glock;
+	ssock->param.grp_lock = glock;
 	pj_grp_lock_add_handler(ssock->param.grp_lock, ssock->pool, ssock,
 				ssl_on_destroy);
     }
@@ -1008,6 +1030,7 @@ static pj_bool_t ssock_on_accept_complete (pj_ssl_sock_t *ssock_parent,
 
     /* Create active socket */
     pj_activesock_cfg_default(&asock_cfg);
+    asock_cfg.grp_lock = ssock->param.grp_lock;
     asock_cfg.async_cnt = ssock->param.async_cnt;
     asock_cfg.concurrency = ssock->param.concurrency;
     asock_cfg.whole_data = PJ_TRUE;

diff --git a/pjlib/src/pj/ssl_sock_ossl.c b/pjlib/src/pj/ssl_sock_ossl.c
@@ -327,7 +327,8 @@ static pj_status_t STATUS_FROM_SSL_ERR(char *action, pj_ssl_sock_t *ssock,
 	ERROR_LOG("STATUS_FROM_SSL_ERR", err, ssock);
     }
 
-    ssock->last_err = err;
+    if (ssock)
+	ssock->last_err = err;
     return GET_STATUS_FROM_SSL_ERR(err);
 }
 
@@ -344,7 +345,8 @@ static pj_status_t STATUS_FROM_SSL_ERR2(char *action, pj_ssl_sock_t *ssock,
     /* Dig for more from OpenSSL error queue */
     SSLLogErrors(action, ret, err, len, ssock);
 
-    ssock->last_err = ssl_err;
+    if (ssock)
+	ssock->last_err = ssl_err;
     return GET_STATUS_FROM_SSL_ERR(ssl_err);
 }
 
@@ -786,6 +788,13 @@ static pj_status_t init_openssl(void)
 
     /* Create OpenSSL application data index for SSL socket */
     sslsock_idx = SSL_get_ex_new_index(0, "SSL socket", NULL, NULL, NULL);
+    if (sslsock_idx == -1) {
+	status = STATUS_FROM_SSL_ERR2("Init", NULL, -1, ERR_get_error(), 0);
+	PJ_LOG(1,(THIS_FILE,
+	       "Fatal error: failed to get application data index for "
+	       "SSL socket"));
+	return status;
+    }
 
 #if defined(PJ_SSL_SOCK_OSSL_USE_THREAD_CB) && \
     PJ_SSL_SOCK_OSSL_USE_THREAD_CB != 0 && OPENSSL_VERSION_NUMBER < 0x10100000L
@@ -819,21 +828,36 @@ static int password_cb(char *buf, int num, int rwflag, void *user_data)
 }
 
 
-/* SSL password callback. */
+/* SSL certificate verification result callback.
+ * Note that this callback seems to be always called from library worker
+ * thread, e.g: active socket on_read_complete callback, which should have
+ * already been equipped with race condition avoidance mechanism (should not
+ * be destroyed while callback is being invoked).
+ */
 static int verify_cb(int preverify_ok, X509_STORE_CTX *x509_ctx)
 {
-    pj_ssl_sock_t *ssock;
-    SSL *ossl_ssl;
+    pj_ssl_sock_t *ssock = NULL;
+    SSL *ossl_ssl = NULL;
     int err;
 
     /* Get SSL instance */
     ossl_ssl = X509_STORE_CTX_get_ex_data(x509_ctx, 
 				    SSL_get_ex_data_X509_STORE_CTX_idx());
-    pj_assert(ossl_ssl);
+    if (!ossl_ssl) {
+	PJ_LOG(1,(THIS_FILE,
+		  "SSL verification callback failed to get SSL instance"));
+	goto on_return;
+    }
 
     /* Get SSL socket instance */
     ssock = SSL_get_ex_data(ossl_ssl, sslsock_idx);
-    pj_assert(ssock);
+    if (!ssock) {
+	/* SSL socket may have been destroyed */
+	PJ_LOG(1,(THIS_FILE,
+		  "SSL verification callback failed to get SSL socket "
+		  "instance (sslsock_idx=%d).", sslsock_idx));
+	goto on_return;
+    }
 
     /* Store verification status */
     err = X509_STORE_CTX_get_error(x509_ctx);
@@ -911,6 +935,7 @@ static int verify_cb(int preverify_ok, X509_STORE_CTX *x509_ctx)
     if (PJ_FALSE == ssock->param.verify_peer)
 	preverify_ok = 1;
 
+on_return:
     return preverify_ok;
 }
 
@@ -1474,6 +1499,12 @@ static void ssl_destroy(pj_ssl_sock_t *ssock)
 static void ssl_reset_sock_state(pj_ssl_sock_t *ssock)
 {
     ossl_sock_t *ossock = (ossl_sock_t *)ssock;
+
+    /* Detach from SSL instance */
+    if (ossock->ossl_ssl) {
+	SSL_set_ex_data(ossock->ossl_ssl, sslsock_idx, NULL);
+    }
+
     /**
      * Avoid calling SSL_shutdown() if handshake wasn't completed.
      * OpenSSL 1.0.2f complains if SSL_shutdown() is called during an

diff --git a/pjsip/src/pjsip/sip_transport_tls.c b/pjsip/src/pjsip/sip_transport_tls.c
@@ -1333,9 +1333,26 @@ static pj_bool_t on_accept_complete2(pj_ssl_sock_t *ssock,
     PJ_UNUSED_ARG(src_addr_len);
 
     listener = (struct tls_listener*) pj_ssl_sock_get_user_data(ssock);
+    if (!listener) {
+	/* Listener already destroyed, e.g: after TCP accept but before SSL
+	 * handshake is completed.
+	 */
+	if (new_ssock && accept_status == PJ_SUCCESS) {
+	    /* Close the SSL socket if the accept op is successful */
+	    PJ_LOG(4,(THIS_FILE,
+		      "Incoming TLS connection from %s (sock=%d) is discarded "
+		      "because listener is already destroyed",
+		      pj_sockaddr_print(src_addr, addr, sizeof(addr), 3),
+		      new_ssock));
+
+	    pj_ssl_sock_close(new_ssock);
+	}
+
+	return PJ_FALSE;
+    }
 
     if (accept_status != PJ_SUCCESS) {
-	if (listener && listener->tls_setting.on_accept_fail_cb) {
+	if (listener->tls_setting.on_accept_fail_cb) {
 	    pjsip_tls_on_accept_fail_param param;
 	    pj_ssl_sock_info ssi;
 
@@ -1358,6 +1375,8 @@ static pj_bool_t on_accept_complete2(pj_ssl_sock_t *ssock,
     PJ_ASSERT_RETURN(new_ssock, PJ_TRUE);
 
     if (!listener->is_registered) {
+	pj_ssl_sock_close(new_ssock);
+
 	if (listener->tls_setting.on_accept_fail_cb) {
 	    pjsip_tls_on_accept_fail_param param;
 	    pj_bzero(&param, sizeof(param));
@@ -1409,6 +1428,8 @@ static pj_bool_t on_accept_complete2(pj_ssl_sock_t *ssock,
 			 ssl_info.grp_lock, &tls);
 
     if (status != PJ_SUCCESS) {
+	pj_ssl_sock_close(new_ssock);
+
 	if (listener->tls_setting.on_accept_fail_cb) {
 	    pjsip_tls_on_accept_fail_param param;
 	    pj_bzero(&param, sizeof(param));