stricter session ID context matching (ccdc9cee) · Commits · CYBER - Cyber Security / TS 103 523 MSP / TLMSP / TLMSP OpenSSL

CHANGES

+10 −1

Original line number	Diff line number	Diff line
		@@ -4,7 +4,16 @@

		Changes between 0.9.7m and 0.9.7n [xx XXX xxxx]

		*)
		*) In the SSL/TLS server implementation, be strict about session ID
		context matching (which matters if an application uses a single
		external cache for different purposes). Previously,
		out-of-context reuse was forbidden only if SSL_VERIFY_PEER was
		set. This did ensure strict client verification, but meant that,
		with applications using a single external cache for quite
		different requirements, clients could circumvent ciphersuite
		restrictions for a given session ID context by starting a session
		in a different context.
		[Bodo Moeller]

		Changes between 0.9.7l and 0.9.7m [23 Feb 2007]

ssl/ssl_sess.c

+23 −21

Original line number	Diff line number	Diff line
		@@ -322,26 +322,12 @@ int ssl_get_prev_session(SSL s, unsigned char session_id, int len)

		/* Now ret is non-NULL, and we own one of its reference counts. */

		if((s->verify_mode&SSL_VERIFY_PEER)
		&& (!s->sid_ctx_length \|\| ret->sid_ctx_length != s->sid_ctx_length
		\|\| memcmp(ret->sid_ctx,s->sid_ctx,ret->sid_ctx_length)))
		if (ret->sid_ctx_length != s->sid_ctx_length
		\|\| memcmp(ret->sid_ctx,s->sid_ctx,ret->sid_ctx_length))
		{
		/* We've found the session named by the client, but we don't
		* want to use it in this context. */

		if (s->sid_ctx_length == 0)
		{
		/* application should have used SSL[_CTX]_set_session_id_context
		* -- we could tolerate this and just pretend we never heard
		* of this session, but then applications could effectively
		* disable the session cache by accident without anyone noticing */

		SSLerr(SSL_F_SSL_GET_PREV_SESSION,SSL_R_SESSION_ID_CONTEXT_UNINITIALIZED);
		fatal = 1;
		goto err;
		}
		else
		{
		#if 0 /* The client cannot always know when a session is not appropriate,
		* so we shouldn't generate an error message. */

		@@ -349,6 +335,22 @@ int ssl_get_prev_session(SSL s, unsigned char session_id, int len)
		#endif
		goto err; /* treat like cache miss */
		}

		if((s->verify_mode & SSL_VERIFY_PEER) && s->sid_ctx_length == 0)
		{
		/* We can't be sure if this session is being used out of
		* context, which is especially important for SSL_VERIFY_PEER.
		* The application should have used SSL[_CTX]_set_session_id_context.
		*
		* For this error case, we generate an error instead of treating
		* the event like a cache miss (otherwise it would be easy for
		* applications to effectively disable the session cache by
		* accident without anyone noticing).
		*/

		SSLerr(SSL_F_SSL_GET_PREV_SESSION,SSL_R_SESSION_ID_CONTEXT_UNINITIALIZED);
		fatal = 1;
		goto err;
		}

		if (ret->cipher == NULL)