[Asterisk-code-review] AST-2021-009 - pjproject-bundled: Avoid crash during handshake for TLS (asterisk[16])

Friendly Automation asteriskteam at digium.com
Thu Jul 22 16:20:14 CDT 2021


Friendly Automation has submitted this change. ( https://gerrit.asterisk.org/c/asterisk/+/16190 )

Change subject: AST-2021-009 - pjproject-bundled: Avoid crash during handshake for TLS
......................................................................

AST-2021-009 - pjproject-bundled: Avoid crash during handshake for TLS

If an SSL socket parent/listener was destroyed during the handshake,
depending on timing, it was possible for the handling callback to
attempt access of it after the fact thus causing a crash.

ASTERISK-29415 #close

Change-Id: I105dacdcd130ea7fdd4cf2010ccf35b5eaf1432d
---
A third-party/pjproject/patches/0110-tls-parent-listener-destroyed.patch
A third-party/pjproject/patches/0111-ssl-premature-destroy.patch
2 files changed, 302 insertions(+), 0 deletions(-)

Approvals:
  Friendly Automation: Looks good to me, approved; Approved for Submit



diff --git a/third-party/pjproject/patches/0110-tls-parent-listener-destroyed.patch b/third-party/pjproject/patches/0110-tls-parent-listener-destroyed.patch
new file mode 100644
index 0000000..81781f2
--- /dev/null
+++ b/third-party/pjproject/patches/0110-tls-parent-listener-destroyed.patch
@@ -0,0 +1,166 @@
+From bb92c97ea512aa0ef316c9b2335c7d57b84dfc9a Mon Sep 17 00:00:00 2001
+From: Nanang Izzuddin <nanang at teluu.com>
+Date: Wed, 16 Jun 2021 12:12:35 +0700
+Subject: [PATCH 1/2] - 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.
+
+---
+ pjlib/src/pj/ssl_sock_imp_common.c  | 44 +++++++++++++++++++++--------
+ pjsip/src/pjsip/sip_transport_tls.c | 23 ++++++++++++++-
+ 2 files changed, 55 insertions(+), 12 deletions(-)
+
+diff --git a/pjlib/src/pj/ssl_sock_imp_common.c b/pjlib/src/pj/ssl_sock_imp_common.c
+index bc468bcb3..abec31805 100644
+--- a/pjlib/src/pj/ssl_sock_imp_common.c
++++ b/pjlib/src/pj/ssl_sock_imp_common.c
+@@ -224,6 +224,8 @@ 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. */
+ 
+@@ -241,6 +243,12 @@ 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
+@@ -284,23 +292,29 @@ 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 */
+@@ -864,9 +878,13 @@ static pj_bool_t asock_on_accept_complete (pj_activesock_t *asock,
+     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, 
+@@ -913,16 +931,20 @@ static pj_bool_t asock_on_accept_complete (pj_activesock_t *asock,
+     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->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;
++		}
+     }
+ 
+     /* Create active socket */
+diff --git a/pjsip/src/pjsip/sip_transport_tls.c b/pjsip/src/pjsip/sip_transport_tls.c
+index 17b7ae3de..ce524d53f 100644
+--- a/pjsip/src/pjsip/sip_transport_tls.c
++++ b/pjsip/src/pjsip/sip_transport_tls.c
+@@ -1325,9 +1325,26 @@ 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;
+ 
+@@ -1350,6 +1367,8 @@ 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));
+@@ -1401,6 +1420,8 @@ 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));
diff --git a/third-party/pjproject/patches/0111-ssl-premature-destroy.patch b/third-party/pjproject/patches/0111-ssl-premature-destroy.patch
new file mode 100644
index 0000000..9de2915
--- /dev/null
+++ b/third-party/pjproject/patches/0111-ssl-premature-destroy.patch
@@ -0,0 +1,136 @@
+From 68c69f516f95df1faa42e5647e9ce7cfdc41ac38 Mon Sep 17 00:00:00 2001
+From: Nanang Izzuddin <nanang at teluu.com>
+Date: Wed, 16 Jun 2021 12:15:29 +0700
+Subject: [PATCH 2/2] - 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.
+
+---
+ pjlib/src/pj/ssl_sock_imp_common.c |  3 +-
+ pjlib/src/pj/ssl_sock_ossl.c       | 45 +++++++++++++++++++++++++-----
+ 2 files changed, 40 insertions(+), 8 deletions(-)
+
+diff --git a/pjlib/src/pj/ssl_sock_imp_common.c b/pjlib/src/pj/ssl_sock_imp_common.c
+index bc468bcb3..c2b8a846b 100644
+--- a/pjlib/src/pj/ssl_sock_imp_common.c
++++ b/pjlib/src/pj/ssl_sock_imp_common.c
+@@ -927,6 +927,7 @@ static pj_bool_t asock_on_accept_complete (pj_activesock_t *asock,
+ 
+     /* 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;
+@@ -942,7 +943,7 @@ static pj_bool_t asock_on_accept_complete (pj_activesock_t *asock,
+ 	    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);
+     }
+diff --git a/pjlib/src/pj/ssl_sock_ossl.c b/pjlib/src/pj/ssl_sock_ossl.c
+index a95b339a5..56841f80a 100644
+--- 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);
+ }
+ 
+@@ -587,6 +589,13 @@ 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;
++	}
+ 
+     return status;
+ }
+@@ -614,21 +623,36 @@ 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);
+@@ -706,6 +730,7 @@ 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;
+ }
+ 
+@@ -1213,6 +1238,12 @@ 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

-- 
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Gerrit-Project: asterisk
Gerrit-Branch: 16
Gerrit-Change-Id: I105dacdcd130ea7fdd4cf2010ccf35b5eaf1432d
Gerrit-Change-Number: 16190
Gerrit-PatchSet: 2
Gerrit-Owner: Friendly Automation
Gerrit-Reviewer: Friendly Automation
Gerrit-MessageType: merged
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