net: avoid false positives in untrusted gso validation

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GSO packets with vnet_hdr must conform to a small set of gso_types.
The below commit uses flow dissection to drop packets that do not.

But it has false positives when the skb is not fully initialized.
Dissection needs skb->protocol and skb->network_header.

Infer skb->protocol from gso_type as the two must agree.
SKB_GSO_UDP can use both ipv4 and ipv6, so try both.

Exclude callers for which network header offset is not known.

Fixes: d5be7f632b ("net: validate untrusted gso packets without csum offload")
Signed-off-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

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Willem de Bruijn 2019-02-18 23:37:12 -05:00 • committed by David S. Miller

parent 06cd1702ee

commit 9e8db59132

1 changed files with 12 additions and 2 deletions

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include/linux/virtio_net.h

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