libceph: handle an empty authorize reply

The authorize reply can be empty, for example when the ticket used to
build the authorizer is too old and TAG_BADAUTHORIZER is returned from
the service.  Calling ->verify_authorizer_reply() results in an attempt
to decrypt and validate (somewhat) random data in au->buf (most likely
the signature block from calc_signature()), which fails and ends up in
con_fault_finish() with !con->auth_retry.  The ticket isn't invalidated
and the connection is retried again and again until a new ticket is
obtained from the monitor:

  libceph: osd2 192.168.122.1:6809 bad authorize reply
  libceph: osd2 192.168.122.1:6809 bad authorize reply
  libceph: osd2 192.168.122.1:6809 bad authorize reply
  libceph: osd2 192.168.122.1:6809 bad authorize reply

Let TAG_BADAUTHORIZER handler kick in and increment con->auth_retry.

Cc: stable@vger.kernel.org
Fixes: 5c056fdc5b47 ("libceph: verify authorize reply on connect")
Link: https://tracker.ceph.com/issues/20164
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
Reviewed-by: Sage Weil <sage@redhat.com>

diff --git a/net/ceph/messenger.c b/net/ceph/messenger.c
index 3661cdd..7e71b0d 100644 (file)
--- a/net/ceph/messenger.c
+++ b/net/ceph/messenger.c
@@ -2058,6 +2058,8 @@ static int process_connect(struct ceph_connection *con)
        dout("process_connect on %p tag %d\n", con, (int)con->in_tag);
 
        if (con->auth) {
+               int len = le32_to_cpu(con->in_reply.authorizer_len);
+
                /*
                 * Any connection that defines ->get_authorizer()
                 * should also define ->add_authorizer_challenge() and
@@ -2067,8 +2069,7 @@ static int process_connect(struct ceph_connection *con)
                 */
                if (con->in_reply.tag == CEPH_MSGR_TAG_CHALLENGE_AUTHORIZER) {
                        ret = con->ops->add_authorizer_challenge(
-                                   con, con->auth->authorizer_reply_buf,
-                                   le32_to_cpu(con->in_reply.authorizer_len));
+                                   con, con->auth->authorizer_reply_buf, len);
                        if (ret < 0)
                                return ret;
 
@@ -2078,10 +2079,12 @@ static int process_connect(struct ceph_connection *con)
                        return 0;
                }
 
-               ret = con->ops->verify_authorizer_reply(con);
-               if (ret < 0) {
-                       con->error_msg = "bad authorize reply";
-                       return ret;
+               if (len) {
+                       ret = con->ops->verify_authorizer_reply(con);
+                       if (ret < 0) {
+                               con->error_msg = "bad authorize reply";
+                               return ret;
+                       }
                }
        }