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if_wg: better loop detection 

While it was nice to have per peer loop detection, it was not meant to
be. The loop tag has a tag type == 0, which conflicts with other tags.
Therefore we want to at least be a little bit more sure that the tag
cookie is unique to the loop tag. I guess the peer address was also
quite hacky so on the other side, I'm glad to be rid of that.

Now we have a loop of 8 (to any peer) which should be good enough for an
edge case operation.

Signed-off-by: Matt Dunwoodie <ncon@noconroy.net>
This commit is contained in:
Matt Dunwoodie 2021-04-22 15:22:53 +10:00 committed by Jason A. Donenfeld
parent eb2d6d7d14
commit 4947482e22
1 changed files with 4 additions and 3 deletions
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7
src/if_wg.c
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@ -272,6 +272,9 @@ struct wg_softc {
#define WGF_DYING 0x0001
#define MAX_LOOPS 8
#define MTAG_WGLOOP 0x77676c70 /* wglp */
/* TODO the following defines are freebsd specific, we should see what is
* necessary and cleanup from there (i suspect a lot can be junked). */
@ -2006,9 +2009,7 @@ wg_transmit(struct ifnet *ifp, struct mbuf *m)
goto err;
}
/* Detect packet loops, TODO make better unique identifier than p_id
* (because it is truncated from uint64_t to uint32_t). */
if (__predict_false(if_tunnel_check_nesting(ifp, m, peer->p_id, 1))) {
if (__predict_false(if_tunnel_check_nesting(ifp, m, MTAG_WGLOOP, MAX_LOOPS))) {
DPRINTF(sc, "Packet looped");
rc = ELOOP;
goto err;