There are cases where GSO segment's length exceeds the egress MTU.
If so:
- Consume the SKB and its segments.
- Issue an ICMP packet with 'Packet Too Big' message containing the
MTU, allowing the source host to reduce its Path MTU appropriately.
Note: These cases are handled in the same manner in IPv4 output finish.
This patch aligns the behavior of IPv6 and IPv4.
Fixes: 9e50849054a4 ("netfilter: ipv6: move POSTROUTING invocation before
fragmentation")
Signed-off-by: Aya Levin <a...@nvidia.com>
Reviewed-by: Tariq Toukan <tar...@nvidia.com>
---
net/ipv6/ip6_output.c | 41 ++++++++++++++++++++++++++++++++++++++++-
1 file changed, 40 insertions(+), 1 deletion(-)
Hi,
Please queue to -stable >= v2.6.35.
Daniel Axtens, does this solve the issue referred in your commit?
8914a595110a bnx2x: disable GSO where gso_size is too big for hardware
Thanks,
Aya
diff --git a/net/ipv6/ip6_output.c b/net/ipv6/ip6_output.c
index 749ad72386b2..36466f2211bd 100644
--- a/net/ipv6/ip6_output.c
+++ b/net/ipv6/ip6_output.c
@@ -125,8 +125,43 @@ static int ip6_finish_output2(struct net *net, struct sock
*sk, struct sk_buff *
return -EINVAL;
}
+static int
+ip6_finish_output_gso_slowpath_drop(struct net *net, struct sock *sk,
+ struct sk_buff *skb, unsigned int mtu)
+{
+ struct sk_buff *segs, *nskb;
+ netdev_features_t features;
+ int ret;
+
+ /* Please see corresponding comment in ip_finish_output_gso
+ * describing the cases where GSO segment length exceeds the
+ * egress MTU.
+ */
+ features = netif_skb_features(skb);
+ segs = skb_gso_segment(skb, features & ~NETIF_F_GSO_MASK);
+ if (IS_ERR_OR_NULL(segs)) {
+ kfree_skb(skb);
+ return -ENOMEM;
+ }
+
+ consume_skb(skb);
+
+ skb_list_walk_safe(segs, segs, nskb) {
+ int err;
+
+ skb_mark_not_on_list(segs);
+ err = ip6_fragment(net, sk, segs, ip6_finish_output2);
+ if (err && ret == 0)
+ ret = err;
+ }
+
+ return ret;
+}
+
static int __ip6_finish_output(struct net *net, struct sock *sk, struct
sk_buff *skb)
{
+ unsigned int mtu;
+
#if defined(CONFIG_NETFILTER) && defined(CONFIG_XFRM)
/* Policy lookup after SNAT yielded a new policy */
if (skb_dst(skb)->xfrm) {
@@ -135,7 +170,11 @@ static int __ip6_finish_output(struct net *net, struct
sock *sk, struct sk_buff
}
#endif
- if ((skb->len > ip6_skb_dst_mtu(skb) && !skb_is_gso(skb)) ||
+ mtu = ip6_skb_dst_mtu(skb);
+ if (skb_is_gso(skb) && !skb_gso_validate_network_len(skb, mtu))
+ return ip6_finish_output_gso_slowpath_drop(net, sk, skb, mtu);
+
+ if ((skb->len > mtu && !skb_is_gso(skb)) ||
dst_allfrag(skb_dst(skb)) ||
(IP6CB(skb)->frag_max_size && skb->len > IP6CB(skb)->frag_max_size))
return ip6_fragment(net, sk, skb, ip6_finish_output2);
--
2.14.1
