Commit 17175d1a authored Jul 03, 2020 by Sabrina Dubroca Committed by Steffen Klassert Jul 07, 2020

xfrm: esp6: fix encapsulation header offset computation



In commit 0146dca7, I incorrectly adapted the code that computes
the location of the UDP or TCP encapsulation header from IPv4 to
IPv6. In esp6_input_done2, skb->transport_header points to the ESP
header, so by adding skb_network_header_len, uh and th will point to
the ESP header, not the encapsulation header that's in front of it.

Since the TCP header's size can change with options, we have to start
from the IPv6 header and walk past possible extensions.

Fixes: 0146dca7 ("xfrm: add support for UDPv6 encapsulation of ESP")
Fixes: 26333c37 ("xfrm: add IPv6 support for espintcp")
Reported-by: Tobias Brunner <tobias@strongswan.org>
Tested-by: Tobias Brunner <tobias@strongswan.org>
Signed-off-by: Sabrina Dubroca <sd@queasysnail.net>
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>

parent 4f47e8ab

net/ipv6/esp6.c

+9 −3

Original line number	Diff line number	Diff line
		@@ -805,10 +805,16 @@ int esp6_input_done2(struct sk_buff *skb, int err)

		if (x->encap) {
		const struct ipv6hdr *ip6h = ipv6_hdr(skb);
		int offset = skb_network_offset(skb) + sizeof(*ip6h);
		struct xfrm_encap_tmpl *encap = x->encap;
		struct udphdr uh = (void )(skb_network_header(skb) + hdr_len);
		struct tcphdr th = (void )(skb_network_header(skb) + hdr_len);
		__be16 source;
		u8 nexthdr = ip6h->nexthdr;
		__be16 frag_off, source;
		struct udphdr *uh;
		struct tcphdr *th;

		offset = ipv6_skip_exthdr(skb, offset, &nexthdr, &frag_off);
		uh = (void *)(skb->data + offset);
		th = (void *)(skb->data + offset);

		switch (x->encap->encap_type) {
		case TCP_ENCAP_ESPINTCP:

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