diff options
author | Jonathan Davies <jonathan.davies@nutanix.com> | 2021-11-16 17:42:42 +0000 |
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committer | David S. Miller <davem@davemloft.net> | 2021-11-17 14:50:45 +0000 |
commit | cf9acc90c80ecbee00334aa85d92f4e74014bcff (patch) | |
tree | 7f3ab1f535418e1d61669832d759366c44007f95 /crypto/testmgr.h | |
parent | 9b5a333272a48c2f8b30add7a874e46e8b26129c (diff) |
net: virtio_net_hdr_to_skb: count transport header in UFO
virtio_net_hdr_to_skb does not set the skb's gso_size and gso_type
correctly for UFO packets received via virtio-net that are a little over
the GSO size. This can lead to problems elsewhere in the networking
stack, e.g. ovs_vport_send dropping over-sized packets if gso_size is
not set.
This is due to the comparison
if (skb->len - p_off > gso_size)
not properly accounting for the transport layer header.
p_off includes the size of the transport layer header (thlen), so
skb->len - p_off is the size of the TCP/UDP payload.
gso_size is read from the virtio-net header. For UFO, fragmentation
happens at the IP level so does not need to include the UDP header.
Hence the calculation could be comparing a TCP/UDP payload length with
an IP payload length, causing legitimate virtio-net packets to have
lack gso_type/gso_size information.
Example: a UDP packet with payload size 1473 has IP payload size 1481.
If the guest used UFO, it is not fragmented and the virtio-net header's
flags indicate that it is a GSO frame (VIRTIO_NET_HDR_GSO_UDP), with
gso_size = 1480 for an MTU of 1500. skb->len will be 1515 and p_off
will be 42, so skb->len - p_off = 1473. Hence the comparison fails, and
shinfo->gso_size and gso_type are not set as they should be.
Instead, add the UDP header length before comparing to gso_size when
using UFO. In this way, it is the size of the IP payload that is
compared to gso_size.
Fixes: 6dd912f82680 ("net: check untrusted gso_size at kernel entry")
Signed-off-by: Jonathan Davies <jonathan.davies@nutanix.com>
Reviewed-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'crypto/testmgr.h')
0 files changed, 0 insertions, 0 deletions