| Message ID | 1345434006-16549-2-git-send-email-kaber@trash.net |
|---|---|
| State | Superseded |
| Headers | show |
On Mon, 2012-08-20 at 05:39 +0200, Patrick McHardy wrote: > IPv4 conntrack defragments incoming packet at the PRE_ROUTING hook and > (in case of forwarded packets) refragments them at POST_ROUTING > independant of the IP_DF flag. Refragmentation uses the dst_mtu() of > the local route without caring about the original fragment sizes, > thereby breaking PMTUD. > > This patch fixes this by keeping track of the largest received fragment > with IP_DF set and generates an ICMP fragmentation required error during > refragmentation if that size exceeds the MTU. > > Signed-off-by: Patrick McHardy <kaber@trash.net> > --- Acked-by: Eric Dumazet <edumazet@google.com> -- To unsubscribe from this list: send the line "unsubscribe netfilter-devel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Monday 2012-08-20 05:39, Patrick McHardy wrote: >IPv4 conntrack defragments incoming packet at the PRE_ROUTING hook and >(in case of forwarded packets) refragments them at POST_ROUTING >independant of the IP_DF flag. "independent". (also in 06/18) -- To unsubscribe from this list: send the line "unsubscribe netfilter-devel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Mon, 20 Aug 2012, Jan Engelhardt wrote: > On Monday 2012-08-20 05:39, Patrick McHardy wrote: > >> IPv4 conntrack defragments incoming packet at the PRE_ROUTING hook and >> (in case of forwarded packets) refragments them at POST_ROUTING >> independant of the IP_DF flag. > > "independent". (also in 06/18) Fixed, thanks. -- To unsubscribe from this list: send the line "unsubscribe netfilter-devel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/include/net/inet_frag.h b/include/net/inet_frag.h index 2431cf8..5098ee7 100644 --- a/include/net/inet_frag.h +++ b/include/net/inet_frag.h @@ -29,6 +29,8 @@ struct inet_frag_queue { #define INET_FRAG_COMPLETE 4 #define INET_FRAG_FIRST_IN 2 #define INET_FRAG_LAST_IN 1 + + u16 max_size; }; #define INETFRAGS_HASHSZ 64 diff --git a/include/net/ip.h b/include/net/ip.h index 5a5d84d..0707fb9 100644 --- a/include/net/ip.h +++ b/include/net/ip.h @@ -42,6 +42,8 @@ struct inet_skb_parm { #define IPSKB_XFRM_TRANSFORMED 4 #define IPSKB_FRAG_COMPLETE 8 #define IPSKB_REROUTED 16 + + u16 frag_max_size; }; static inline unsigned int ip_hdrlen(const struct sk_buff *skb) diff --git a/net/ipv4/ip_fragment.c b/net/ipv4/ip_fragment.c index 8d07c97..fa6a12c 100644 --- a/net/ipv4/ip_fragment.c +++ b/net/ipv4/ip_fragment.c @@ -523,6 +523,10 @@ found: if (offset == 0) qp->q.last_in |= INET_FRAG_FIRST_IN; + if (ip_hdr(skb)->frag_off & htons(IP_DF) && + skb->len + ihl > qp->q.max_size) + qp->q.max_size = skb->len + ihl; + if (qp->q.last_in == (INET_FRAG_FIRST_IN | INET_FRAG_LAST_IN) && qp->q.meat == qp->q.len) return ip_frag_reasm(qp, prev, dev); @@ -646,9 +650,11 @@ static int ip_frag_reasm(struct ipq *qp, struct sk_buff *prev, head->next = NULL; head->dev = dev; head->tstamp = qp->q.stamp; + IPCB(head)->frag_max_size = qp->q.max_size; iph = ip_hdr(head); - iph->frag_off = 0; + /* max_size != 0 implies at least one fragment had IP_DF set */ + iph->frag_off = qp->q.max_size ? htons(IP_DF) : 0; iph->tot_len = htons(len); iph->tos |= ecn; IP_INC_STATS_BH(net, IPSTATS_MIB_REASMOKS); diff --git a/net/ipv4/ip_output.c b/net/ipv4/ip_output.c index 147ccc3..95a9d72 100644 --- a/net/ipv4/ip_output.c +++ b/net/ipv4/ip_output.c @@ -467,7 +467,9 @@ int ip_fragment(struct sk_buff *skb, int (*output)(struct sk_buff *)) iph = ip_hdr(skb); - if (unlikely((iph->frag_off & htons(IP_DF)) && !skb->local_df)) { + if (unlikely(((iph->frag_off & htons(IP_DF)) && !skb->local_df) || + (IPCB(skb)->frag_max_size && + IPCB(skb)->frag_max_size > dst_mtu(&rt->dst)))) { IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGFAILS); icmp_send(skb, ICMP_DEST_UNREACH, ICMP_FRAG_NEEDED, htonl(ip_skb_dst_mtu(skb)));
IPv4 conntrack defragments incoming packet at the PRE_ROUTING hook and (in case of forwarded packets) refragments them at POST_ROUTING independant of the IP_DF flag. Refragmentation uses the dst_mtu() of the local route without caring about the original fragment sizes, thereby breaking PMTUD. This patch fixes this by keeping track of the largest received fragment with IP_DF set and generates an ICMP fragmentation required error during refragmentation if that size exceeds the MTU. Signed-off-by: Patrick McHardy <kaber@trash.net> --- include/net/inet_frag.h | 2 ++ include/net/ip.h | 2 ++ net/ipv4/ip_fragment.c | 8 +++++++- net/ipv4/ip_output.c | 4 +++- 4 files changed, 14 insertions(+), 2 deletions(-)