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ipv6: re-enable fragment header matching in ipv6_find_hdr 

When ipv6_find_hdr is used to find a fragment header
(caller specifies target NEXTHDR_FRAGMENT) we erronously return
-ENOENT for all fragments with nonzero offset.

Before commit 9195bb8e38, when target was specified, we did not
enter the exthdr walk loop as nexthdr == target so this used to work.

Now we do (so we can skip empty route headers). When we then stumble upon
a frag with nonzero frag_off we must return -ENOENT ("header not found")
only if the caller did not specifically request NEXTHDR_FRAGMENT.

This allows nfables exthdr expression to match ipv6 fragments, e.g. via

nft add rule ip6 filter input frag frag-off gt 0

Fixes: 9195bb8e38 ("ipv6: improve ipv6_find_hdr() to skip empty routing headers")
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Florian Westphal 2016-03-01 16:15:16 +01:00 committed by David S. Miller
parent bf13c94ccb
commit 5d150a9855
1 changed files with 5 additions and 1 deletions
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6
net/ipv6/exthdrs_core.c
View File

@ -257,7 +257,11 @@ int ipv6_find_hdr(const struct sk_buff *skb, unsigned int *offset,
*fragoff = _frag_off;
return hp->nexthdr;
}
return -ENOENT;
if (!found)
return -ENOENT;
if (fragoff)
*fragoff = _frag_off;
break;
}
hdrlen = 8;
} else if (nexthdr == NEXTHDR_AUTH) {