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authorEric Dumazet <edumazet@google.com>2015-07-27 11:33:50 +0200
committerDavid S. Miller <davem@davemloft.net>2015-07-28 23:41:24 -0700
commit11c91ef98f37cd743098de26160fffd7f9bd40e1 (patch)
treefbac25bfba3cd3487b659d37cf31d5d9d5c7070a /net/ipv4
parent865b804244f228e80fb62abe464296399253cce8 (diff)
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arp: filter NOARP neighbours for SIOCGARP
When arp is off on a device, and ioctl(SIOCGARP) is queried, a buggy answer is given with MAC address of the device, instead of the mac address of the destination/gateway. We filter out NUD_NOARP neighbours for /proc/net/arp, we must do the same for SIOCGARP ioctl. Tested: lpaa23:~# ./arp 10.246.7.190 MAC=00:01:e8:22:cb:1d // correct answer lpaa23:~# ip link set dev eth0 arp off lpaa23:~# cat /proc/net/arp # check arp table is now 'empty' IP address HW type Flags HW address Mask Device lpaa23:~# ./arp 10.246.7.190 MAC=00:1a:11:c3:0d:7f // buggy answer before patch (this is eth0 mac) After patch : lpaa23:~# ip link set dev eth0 arp off lpaa23:~# ./arp 10.246.7.190 ioctl(SIOCGARP) failed: No such device or address Signed-off-by: Eric Dumazet <edumazet@google.com> Reported-by: Vytautas Valancius <valas@google.com> Cc: Willem de Bruijn <willemb@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/ipv4')
-rw-r--r--net/ipv4/arp.c16
1 files changed, 9 insertions, 7 deletions
diff --git a/net/ipv4/arp.c b/net/ipv4/arp.c
index 933a92820d26..6c8b1fbafce8 100644
--- a/net/ipv4/arp.c
+++ b/net/ipv4/arp.c
@@ -1017,14 +1017,16 @@ static int arp_req_get(struct arpreq *r, struct net_device *dev)
neigh = neigh_lookup(&arp_tbl, &ip, dev);
if (neigh) {
- read_lock_bh(&neigh->lock);
- memcpy(r->arp_ha.sa_data, neigh->ha, dev->addr_len);
- r->arp_flags = arp_state_to_flags(neigh);
- read_unlock_bh(&neigh->lock);
- r->arp_ha.sa_family = dev->type;
- strlcpy(r->arp_dev, dev->name, sizeof(r->arp_dev));
+ if (!(neigh->nud_state & NUD_NOARP)) {
+ read_lock_bh(&neigh->lock);
+ memcpy(r->arp_ha.sa_data, neigh->ha, dev->addr_len);
+ r->arp_flags = arp_state_to_flags(neigh);
+ read_unlock_bh(&neigh->lock);
+ r->arp_ha.sa_family = dev->type;
+ strlcpy(r->arp_dev, dev->name, sizeof(r->arp_dev));
+ err = 0;
+ }
neigh_release(neigh);
- err = 0;
}
return err;
}