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Date: Wed, 30 Dec 2020 14:23:48 +0200 From: Aya Levin <ayal@...dia.com> To: "David S. Miller" <davem@...emloft.net>, Jakub Kicinski <kuba@...nel.org> Cc: Daniel Axtens <dja@...ens.net>, netdev@...r.kernel.org, Moshe Shemesh <moshe@...lanox.com>, Tariq Toukan <tariqt@...dia.com>, Aya Levin <ayal@...dia.com> Subject: [PATCH net] net: ipv6: Validate GSO SKB before finish IPv6 processing 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 <ayal@...dia.com> Reviewed-by: Tariq Toukan <tariqt@...dia.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
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