diff options
| author | Florian Westphal <fw@strlen.de> | 2015-05-22 00:06:40 +0200 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2015-05-25 00:08:48 -0400 |
| commit | cf826244322443215c156c0751fa2c982969a9c9 (patch) | |
| tree | 31f552f87a5ed28fb63187e77f2a5802a863ec3b | |
| parent | b10e3d6c2e557e1dd62c0b6276707b68aa0e5287 (diff) | |
ip: reject too-big defragmented DF-skb when forwarding
Send icmp pmtu error if we find that the largest fragment of df-skb
exceeded the output path mtu.
The ip output path will still catch this later on but we can avoid the
forward/postrouting hook traversal by rejecting right away.
This is what ipv6 already does.
Acked-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: David S. Miller <davem@davemloft.net>
| -rw-r--r-- | net/ipv4/ip_forward.c | 18 |
1 files changed, 11 insertions, 7 deletions
diff --git a/net/ipv4/ip_forward.c b/net/ipv4/ip_forward.c index 3674484946a5..2d3aa408fbdc 100644 --- a/net/ipv4/ip_forward.c +++ b/net/ipv4/ip_forward.c @@ -39,17 +39,21 @@ #include <net/route.h> #include <net/xfrm.h> -static bool ip_may_fragment(const struct sk_buff *skb) -{ - return unlikely((ip_hdr(skb)->frag_off & htons(IP_DF)) == 0) || - skb->ignore_df; -} - static bool ip_exceeds_mtu(const struct sk_buff *skb, unsigned int mtu) { if (skb->len <= mtu) return false; + if (unlikely((ip_hdr(skb)->frag_off & htons(IP_DF)) == 0)) + return false; + + /* original fragment exceeds mtu and DF is set */ + if (unlikely(IPCB(skb)->frag_max_size > mtu)) + return true; + + if (skb->ignore_df) + return false; + if (skb_is_gso(skb) && skb_gso_network_seglen(skb) <= mtu) return false; @@ -114,7 +118,7 @@ int ip_forward(struct sk_buff *skb) IPCB(skb)->flags |= IPSKB_FORWARDED; mtu = ip_dst_mtu_maybe_forward(&rt->dst, true); - if (!ip_may_fragment(skb) && ip_exceeds_mtu(skb, mtu)) { + if (ip_exceeds_mtu(skb, mtu)) { IP_INC_STATS(dev_net(rt->dst.dev), IPSTATS_MIB_FRAGFAILS); icmp_send(skb, ICMP_DEST_UNREACH, ICMP_FRAG_NEEDED, htonl(mtu)); |