| Message ID | 400ebbc750178183155a9419cd5c3d32f53abcef.1616692794.git.pabeni@redhat.com (mailing list archive) |
|---|---|
| State | Superseded |
| Delegated to: | Netdev Maintainers |
| Headers | show |
| Series | udp: GRO L4 improvements | expand |
| Context | Check | Description |
|---|---|---|
| netdev/cover_letter | success | Link |
| netdev/fixes_present | success | Link |
| netdev/patch_count | success | Link |
| netdev/tree_selection | success | Clearly marked for net-next |
| netdev/subject_prefix | success | Link |
| netdev/cc_maintainers | warning | 2 maintainers not CCed: yoshfuji@linux-ipv6.org dsahern@kernel.org |
| netdev/source_inline | success | Was 0 now: 0 |
| netdev/verify_signedoff | success | Link |
| netdev/module_param | success | Was 0 now: 0 |
| netdev/build_32bit | success | Errors and warnings before: 8 this patch: 8 |
| netdev/kdoc | success | Errors and warnings before: 0 this patch: 0 |
| netdev/verify_fixes | success | Link |
| netdev/checkpatch | warning | WARNING: line length of 82 exceeds 80 columns WARNING: line length of 87 exceeds 80 columns |
| netdev/build_allmodconfig_warn | success | Errors and warnings before: 8 this patch: 8 |
| netdev/header_inline | success | Link |
On Thu, Mar 25, 2021 at 1:24 PM Paolo Abeni <pabeni@redhat.com> wrote: > > If NETIF_F_GRO_FRAGLIST or NETIF_F_GRO_UDP_FWD are enabled, and there > are UDP tunnels available in the system, udp_gro_receive() could end-up > doing L4 aggregation (either SKB_GSO_UDP_L4 or SKB_GSO_FRAGLIST) at > the outer UDP tunnel level for packets effectively carrying and UDP > tunnel header. > > That could cause inner protocol corruption. If e.g. the relevant > packets carry a vxlan header, different vxlan ids will be ignored/ > aggregated to the same GSO packet. Inner headers will be ignored, too, > so that e.g. TCP over vxlan push packets will be held in the GRO > engine till the next flush, etc. > > Just skip the SKB_GSO_UDP_L4 and SKB_GSO_FRAGLIST code path if the > current packet could land in a UDP tunnel, and let udp_gro_receive() > do GRO via udp_sk(sk)->gro_receive. > > The check implemented in this patch is broader than what is strictly > needed, as the existing UDP tunnel could be e.g. configured on top of > a different device: we could end-up skipping GRO at-all for some packets. > > Anyhow, the latter is a very thin corner case and covering it would add > quite a bit of complexity. > > v1 -> v2: > - hopefully clarify the commit message > > Fixes: 9fd1ff5d2ac7 ("udp: Support UDP fraglist GRO/GSO.") > Fixes: 36707061d6ba ("udp: allow forwarding of plain (non-fraglisted) UDP GRO packets") > Signed-off-by: Paolo Abeni <pabeni@redhat.com> Reviewed-by: Willem de Bruijn <willemb@google.com> Key is that udp tunnel GRO must take precedence over transport GRO, but the way the code is structured, the latter is tried first.
diff --git a/net/ipv4/udp_offload.c b/net/ipv4/udp_offload.c index c5b4b586570fe..25134a3548e99 100644 --- a/net/ipv4/udp_offload.c +++ b/net/ipv4/udp_offload.c @@ -515,21 +515,24 @@ struct sk_buff *udp_gro_receive(struct list_head *head, struct sk_buff *skb, unsigned int off = skb_gro_offset(skb); int flush = 1; + /* we can do L4 aggregation only if the packet can't land in a tunnel + * otherwise we could corrupt the inner stream + */ NAPI_GRO_CB(skb)->is_flist = 0; - if (skb->dev->features & NETIF_F_GRO_FRAGLIST) - NAPI_GRO_CB(skb)->is_flist = sk ? !udp_sk(sk)->gro_enabled: 1; + if (!sk || !udp_sk(sk)->gro_receive) { + if (skb->dev->features & NETIF_F_GRO_FRAGLIST) + NAPI_GRO_CB(skb)->is_flist = sk ? !udp_sk(sk)->gro_enabled : 1; - if ((!sk && (skb->dev->features & NETIF_F_GRO_UDP_FWD)) || - (sk && udp_sk(sk)->gro_enabled) || NAPI_GRO_CB(skb)->is_flist) { - pp = call_gro_receive(udp_gro_receive_segment, head, skb); + if ((!sk && (skb->dev->features & NETIF_F_GRO_UDP_FWD)) || + (sk && udp_sk(sk)->gro_enabled) || NAPI_GRO_CB(skb)->is_flist) + pp = call_gro_receive(udp_gro_receive_segment, head, skb); return pp; } - if (!sk || NAPI_GRO_CB(skb)->encap_mark || + if (NAPI_GRO_CB(skb)->encap_mark || (uh->check && skb->ip_summed != CHECKSUM_PARTIAL && NAPI_GRO_CB(skb)->csum_cnt == 0 && - !NAPI_GRO_CB(skb)->csum_valid) || - !udp_sk(sk)->gro_receive) + !NAPI_GRO_CB(skb)->csum_valid)) goto out; /* mark that this skb passed once through the tunnel gro layer */
If NETIF_F_GRO_FRAGLIST or NETIF_F_GRO_UDP_FWD are enabled, and there are UDP tunnels available in the system, udp_gro_receive() could end-up doing L4 aggregation (either SKB_GSO_UDP_L4 or SKB_GSO_FRAGLIST) at the outer UDP tunnel level for packets effectively carrying and UDP tunnel header. That could cause inner protocol corruption. If e.g. the relevant packets carry a vxlan header, different vxlan ids will be ignored/ aggregated to the same GSO packet. Inner headers will be ignored, too, so that e.g. TCP over vxlan push packets will be held in the GRO engine till the next flush, etc. Just skip the SKB_GSO_UDP_L4 and SKB_GSO_FRAGLIST code path if the current packet could land in a UDP tunnel, and let udp_gro_receive() do GRO via udp_sk(sk)->gro_receive. The check implemented in this patch is broader than what is strictly needed, as the existing UDP tunnel could be e.g. configured on top of a different device: we could end-up skipping GRO at-all for some packets. Anyhow, the latter is a very thin corner case and covering it would add quite a bit of complexity. v1 -> v2: - hopefully clarify the commit message Fixes: 9fd1ff5d2ac7 ("udp: Support UDP fraglist GRO/GSO.") Fixes: 36707061d6ba ("udp: allow forwarding of plain (non-fraglisted) UDP GRO packets") Signed-off-by: Paolo Abeni <pabeni@redhat.com> --- net/ipv4/udp_offload.c | 19 +++++++++++-------- 1 file changed, 11 insertions(+), 8 deletions(-)