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ipv6: Fix IPsec slowpath fragmentation problem 

ip6_append_data() builds packets based on the mtu from dst_mtu(rt->dst.path).
On IPsec the effective mtu is lower because we need to add the protocol
headers and trailers later when we do the IPsec transformations. So after
the IPsec transformations the packet might be too big, which leads to a
slowpath fragmentation then. This patch fixes this by building the packets
based on the lower IPsec mtu from dst_mtu(&rt->dst) and adapts the exthdr
handling to this.

Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Steffen Klassert 2011-10-11 01:43:33 +00:00 committed by David S. Miller
parent c113464d43
commit 299b076764
2 changed files with 13 additions and 8 deletions
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18
net/ipv6/ip6_output.c
View File

@ -1193,6 +1193,7 @@ int ip6_append_data(struct sock *sk, int getfrag(void *from, char *to,
struct sk_buff *skb;
unsigned int maxfraglen, fragheaderlen;
int exthdrlen;
int dst_exthdrlen;
int hh_len;
int mtu;
int copy;
@ -1248,7 +1249,7 @@ int ip6_append_data(struct sock *sk, int getfrag(void *from, char *to,
np->cork.hop_limit = hlimit;
np->cork.tclass = tclass;
mtu = np->pmtudisc == IPV6_PMTUDISC_PROBE ?
rt->dst.dev->mtu : dst_mtu(rt->dst.path);
rt->dst.dev->mtu : dst_mtu(&rt->dst);
if (np->frag_size < mtu) {
if (np->frag_size)
mtu = np->frag_size;
@ -1259,16 +1260,17 @@ int ip6_append_data(struct sock *sk, int getfrag(void *from, char *to,
cork->length = 0;
sk->sk_sndmsg_page = NULL;
sk->sk_sndmsg_off = 0;
exthdrlen = rt->dst.header_len + (opt ? opt->opt_flen : 0) -
rt->rt6i_nfheader_len;
exthdrlen = (opt ? opt->opt_flen : 0) - rt->rt6i_nfheader_len;
length += exthdrlen;
transhdrlen += exthdrlen;
dst_exthdrlen = rt->dst.header_len;
} else {
rt = (struct rt6_info *)cork->dst;
fl6 = &inet->cork.fl.u.ip6;
opt = np->cork.opt;
transhdrlen = 0;
exthdrlen = 0;
dst_exthdrlen = 0;
mtu = cork->fragsize;
}
@ -1368,6 +1370,8 @@ alloc_new_skb:
else
alloclen = datalen + fragheaderlen;
alloclen += dst_exthdrlen;
/*
* The last fragment gets additional space at tail.
* Note: we overallocate on fragments with MSG_MODE
@ -1419,9 +1423,9 @@ alloc_new_skb:
/*
* Find where to start putting bytes
*/
data = skb_put(skb, fraglen);
skb_set_network_header(skb, exthdrlen);
data += fragheaderlen;
data = skb_put(skb, fraglen + dst_exthdrlen);
skb_set_network_header(skb, exthdrlen + dst_exthdrlen);
data += fragheaderlen + dst_exthdrlen;
skb->transport_header = (skb->network_header +
fragheaderlen);
if (fraggap) {
@ -1434,6 +1438,7 @@ alloc_new_skb:
pskb_trim_unique(skb_prev, maxfraglen);
}
copy = datalen - transhdrlen - fraggap;
if (copy < 0) {
err = -EINVAL;
kfree_skb(skb);
@ -1448,6 +1453,7 @@ alloc_new_skb:
length -= datalen - fraggap;
transhdrlen = 0;
exthdrlen = 0;
dst_exthdrlen = 0;
csummode = CHECKSUM_NONE;
/*

3
net/ipv6/raw.c
View File

@ -542,8 +542,7 @@ static int rawv6_push_pending_frames(struct sock *sk, struct flowi6 *fl6,
goto out;
offset = rp->offset;
total_len = inet_sk(sk)->cork.base.length - (skb_network_header(skb) -
skb->data);
total_len = inet_sk(sk)->cork.base.length;
if (offset >= total_len - 1) {
err = -EINVAL;
ip6_flush_pending_frames(sk);