qemu-bridge-helper: restrict interface name to IFNAMSIZ

The network interface name in Linux is defined to be of size
IFNAMSIZ(=16), including the terminating null('\0') byte.
The same is applied to interface names read from 'bridge.conf'
file to form ACL rules. If user supplied '--br=bridge' name
is not restricted to the same length, it could lead to ACL bypass
issue. Restrict interface name to IFNAMSIZ, including null byte.

Reported-by: Riccardo Schirone <rschiron@redhat.com>
Signed-off-by: Prasad J Pandit <pjp@fedoraproject.org>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
Reviewed-by: Li Qiang <liq3ea@gmail.com>
Signed-off-by: Jason Wang <jasowang@redhat.com>
(cherry picked from commit 6f5d8671225dc77190647f18a27a0d156d4ca97a)
Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>

diff --git a/qemu-bridge-helper.c b/qemu-bridge-helper.c
index 5396fbfbb6ca5d4415bd3165dc68bb4f5004a7a0..2c9614e28ef36e18205fc3d93f13fddcdea5eb39 100644 (file)
--- a/qemu-bridge-helper.c
+++ b/qemu-bridge-helper.c
@@ -109,6 +109,13 @@ static int parse_acl_file(const char *filename, ACLList *acl_list)
         }
         *argend = 0;
 
+        if (!g_str_equal(cmd, "include") && strlen(arg) >= IFNAMSIZ) {
+            fprintf(stderr, "name `%s' too long: %zu\n", arg, strlen(arg));
+            fclose(f);
+            errno = EINVAL;
+            return -1;
+        }
+
         if (strcmp(cmd, "deny") == 0) {
             acl_rule = g_malloc(sizeof(*acl_rule));
             if (strcmp(arg, "all") == 0) {
@@ -259,6 +266,10 @@ int main(int argc, char **argv)
         usage();
         return EXIT_FAILURE;
     }
+    if (strlen(bridge) >= IFNAMSIZ) {
+        fprintf(stderr, "name `%s' too long: %zu\n", bridge, strlen(bridge));
+        return EXIT_FAILURE;
+    }
 
     /* parse default acl file */
     QSIMPLEQ_INIT(&acl_list);