From: Eric Dumazet edumazet@google.com
commit 7c6d2ecbda83150b2036a2b36b21381ad4667762 upstream.
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 Cc: Guenter Roeck linux@roeck-us.net Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- include/linux/virtio_net.h | 17 +++++++++-------- 1 file changed, 9 insertions(+), 8 deletions(-)
diff --git a/include/linux/virtio_net.h b/include/linux/virtio_net.h index a16e0bdf77511..d19bfdcf77498 100644 --- a/include/linux/virtio_net.h +++ b/include/linux/virtio_net.h @@ -107,16 +107,17 @@ static inline int virtio_net_hdr_to_skb(struct sk_buff *skb,
if (hdr->gso_type != VIRTIO_NET_HDR_GSO_NONE) { u16 gso_size = __virtio16_to_cpu(little_endian, hdr->gso_size); + struct skb_shared_info *shinfo = skb_shinfo(skb);
- if (skb->len - p_off <= gso_size) - return -EINVAL; - - skb_shinfo(skb)->gso_size = gso_size; - skb_shinfo(skb)->gso_type = gso_type; + /* Too small packets are not really GSO ones. */ + if (skb->len - p_off > gso_size) { + shinfo->gso_size = gso_size; + shinfo->gso_type = gso_type;
- /* Header must be checked, and gso_segs computed. */ - skb_shinfo(skb)->gso_type |= SKB_GSO_DODGY; - skb_shinfo(skb)->gso_segs = 0; + /* Header must be checked, and gso_segs computed. */ + shinfo->gso_type |= SKB_GSO_DODGY; + shinfo->gso_segs = 0; + } }
return 0;