net: be more gentle about silly gso requests coming from user
authorEric Dumazet <edumazet@google.com>
Thu, 28 May 2020 21:57:47 +0000 (14:57 -0700)
committerDavid S. Miller <davem@davemloft.net>
Thu, 28 May 2020 23:31:30 +0000 (16:31 -0700)
commit7c6d2ecbda83150b2036a2b36b21381ad4667762
tree78135e20eb93f2f4d0eb4489fc0a70d4949c7a0f
parent45ebf73ebcec88a34a778f5feaa0b82b1c76069e
net: be more gentle about silly gso requests coming from user

Recent change in virtio_net_hdr_to_skb() broke some packetdrill tests.

When --mss=XXX option is set, packetdrill always provide gso_type & gso_size
for its inbound packets, regardless of packet size.

if (packet->tcp && packet->mss) {
if (packet->ipv4)
gso.gso_type = VIRTIO_NET_HDR_GSO_TCPV4;
else
gso.gso_type = VIRTIO_NET_HDR_GSO_TCPV6;
gso.gso_size = packet->mss;
}

Since many other programs could do the same, relax virtio_net_hdr_to_skb()
to no longer return an error, but instead ignore gso settings.

This keeps Willem intent to make sure no malicious packet could
reach gso stack.

Note that TCP stack has a special logic in tcp_set_skb_tso_segs()
to clear gso_size for small packets.

Fixes: 6dd912f82680 ("net: check untrusted gso_size at kernel entry")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Willem de Bruijn <willemb@google.com>
Acked-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
include/linux/virtio_net.h