AST-2012-013: Resolve ACL rules being ignored during calls by some IAX2 peers

When an IAX2 call is made using the credentials of a peer defined in a dynamic
Asterisk Realtime Architecture (ARA) backend, the ACL rules for that peer are
not applied to the call attempt. This allows for a remote attacker who is aware
of a peer's credentials to bypass the ACL rules set for that peer.

This patch ensures that the ACLs are applied for all peers, regardless of their
storage mechanism.

(closes issue ASTERISK-20186)
Reported by: Alan Frisch
Tested by: mjordan, Alan Frisch
........

Merged revisions 372028 from http://svn.asterisk.org/svn/asterisk/branches/11


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@372029 65c4cc65-6c06-0410-ace0-fbb531ad65f3

channels/chan_iax2.c

@@ -7699,7 +7699,7 @@ static int check_access(int callno, struct sockaddr_in *sin, struct iax_ies *ies
 	while ((user = ao2_iterator_next(&i))) {
 		if ((ast_strlen_zero(iaxs[callno]->username) ||				/* No username specified */
 			!strcmp(iaxs[callno]->username, user->name))	/* Or this username specified */
-			&& ast_apply_acl(user->acl, &addr, "IAX2 user ACL: ")	/* Access is permitted from this IP */
+			&& (ast_apply_acl(user->acl, &addr, "IAX2 user ACL: ") == AST_SENSE_ALLOW)	/* Access is permitted from this IP */
 			&& (ast_strlen_zero(iaxs[callno]->context) ||			/* No context specified */
 			     apply_context(user->contexts, iaxs[callno]->context))) {			/* Context is permitted */
 			if (!ast_strlen_zero(iaxs[callno]->username)) {
@@ -7757,8 +7757,9 @@ static int check_access(int callno, struct sockaddr_in *sin, struct iax_ies *ies
 	user = best;
 	if (!user && !ast_strlen_zero(iaxs[callno]->username)) {
 		user = realtime_user(iaxs[callno]->username, sin);
-		if (user && !ast_strlen_zero(iaxs[callno]->context) &&			/* No context specified */
+		if (user && (ast_apply_acl(user->acl, &addr, "IAX2 user ACL: ") == AST_SENSE_DENY		/* Access is denied from this IP */
-		    !apply_context(user->contexts, iaxs[callno]->context)) {		/* Context is permitted */
+			|| (!ast_strlen_zero(iaxs[callno]->context) &&					/* No context specified */
+				!apply_context(user->contexts, iaxs[callno]->context)))) {	/* Context is permitted */
 			user = user_unref(user);
 		}
 	}