Security fix AST-2009-001

git-svn-id: http://svn.digium.com/svn/asterisk/tags/1.4.22.1@167280 f38db490-d61c-443f-a65b-d21fe96a405b

3 files changed, 23 insertions, 5 deletions

diff --git a/.version b/.version
index d6e261679..688a210c4 100644
--- a/.version
+++ b/.version
@@ -1 +1 @@
-1.4.22
+1.4.22.1
diff --git a/ChangeLog b/ChangeLog
index ddbce9be8..d6f1569d4 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,9 @@
+2009-01-06  Tilghman Lesher <tlesher@digium.com>
+
+	* Asterisk 1.4.22.1 released.
+
+	* channels/chan_iax2.c: Security fix AST-2009-01
+
 2008-10-01  Russell Bryant <russell@digium.com>
 
 	* Asterisk 1.4.22 released.
diff --git a/channels/chan_iax2.c b/channels/chan_iax2.c
index 5d83f6280..67177b13e 100644
--- a/channels/chan_iax2.c
+++ b/channels/chan_iax2.c
@@ -155,6 +155,7 @@ static int trunkfreq = 20;
 static int authdebug = 1;
 static int autokill = 0;
 static int iaxcompat = 0;
+static int last_authmethod = 0;
 
 static int iaxdefaultdpcache=10 * 60;	/* Cache dialplan entries for 10 minutes by default */
 
@@ -6309,23 +6310,34 @@ static int registry_authrequest(int callno)
 	char challenge[10];
 	const char *peer_name;
 	int res = -1;
+	int sentauthmethod;
 
 	peer_name = ast_strdupa(iaxs[callno]->peer);
 
 	/* SLD: third call to find_peer in registration */
 	ast_mutex_unlock(&iaxsl[callno]);
-	p = find_peer(peer_name, 1);
+	if (p = find_peer(peer_name, 1)) {
+		last_authmethod = p->authmethods;
+	}
+
 	ast_mutex_lock(&iaxsl[callno]);
 	if (!iaxs[callno])
 		goto return_unref;
-	if (!p) {
+	if (!p && !delayreject) {
 		ast_log(LOG_WARNING, "No such peer '%s'\n", peer_name);
 		goto return_unref;
 	}
 	
 	memset(&ied, 0, sizeof(ied));
-	iax_ie_append_short(&ied, IAX_IE_AUTHMETHODS, p->authmethods);
-	if (p->authmethods & (IAX_AUTH_RSA | IAX_AUTH_MD5)) {
+	/* The selection of which delayed reject is sent may leak information,
+	 * if it sets a static response.  For example, if a host is known to only
+	 * use MD5 authentication, then an RSA response would indicate that the
+	 * peer does not exist, and vice-versa.
+	 * Therefore, we use whatever the last peer used (which may vary over the
+	 * course of a server, which should leak minimal information). */
+	sentauthmethod = p ? p->authmethods : last_authmethod ? last_authmethod : (IAX_AUTH_MD5 | IAX_AUTH_PLAINTEXT);
+	iax_ie_append_short(&ied, IAX_IE_AUTHMETHODS, sentauthmethod);
+	if (sentauthmethod & (IAX_AUTH_RSA | IAX_AUTH_MD5)) {
 		/* Build the challenge */
 		snprintf(challenge, sizeof(challenge), "%d", (int)ast_random());
 		ast_string_field_set(iaxs[callno], challenge, challenge);