bfdd: Fix malformed session with vrf

With this configuration:

```
bfd
 peer 33:33::66 local-address 33:33::88 vrf vrf8 interface enp1s0
 exit
 !
exit
```

The bfd session can't be established with error:

```
bfdd[18663]: [YA0Q5-C0BPV] control-packet: wrong vrfid. [mhop:no peer:33:33::66 local:33:33::88 port:2 vrf:61]
```

The vrf check should use the carefully adjusted `vrfid`, which is
based on globally/reliable interface.  We can't believe the
`bvrf->vrf->vrf_id` because the `/proc/sys/net/ipv4/udp_l3mdev_accept`
maybe is set "1" in VRF-lite backend even with security drawback.

Just correct the vrf check.

Signed-off-by: anlan_cs <vic.lan@pica8.com>
(cherry picked from commit b17c179664da7331a4669a1cf548e4e9c48a5477)

diff --git a/bfdd/bfd_packet.c b/bfdd/bfd_packet.c
index 6397aa574735fac4d06deab68590ce54a6eb6207..603d220069079ac7b0911db7126a09417dc34f66 100644 (file)
--- a/bfdd/bfd_packet.c
+++ b/bfdd/bfd_packet.c
@@ -896,7 +896,7 @@ void bfd_recv_cb(struct thread *t)
        /*
         * We may have a situation where received packet is on wrong vrf
         */
-       if (bfd && bfd->vrf && bfd->vrf != bvrf->vrf) {
+       if (bfd && bfd->vrf && bfd->vrf->vrf_id != vrfid) {
                cp_debug(is_mhop, &peer, &local, ifindex, vrfid,
                         "wrong vrfid.");
                return;