udp: avoid ufo handling on IP payload compression packets

commit 4b3b45edba9222e518a1ec72df841eba3609fe34 upstream.

commit c146066ab802 ("ipv4: Don't use ufo handling on later transformed
packets") and commit f89c56ce710a ("ipv6: Don't use ufo handling on
later transformed packets") added a check that 'rt->dst.header_len' isn't
zero in order to skip UFO, but it doesn't include IPcomp in transport mode
where it equals zero.

Packets, after payload compression, may not require further fragmentation,
and if original length exceeds MTU, later compressed packets will be
transmitted incorrectly. This can be reproduced with LTP udp_ipsec.sh test
on veth device with enabled UFO, MTU is 1500 and UDP payload is 2000:

* IPv4 case, offset is wrong + unnecessary fragmentation
    udp_ipsec.sh -p comp -m transport -s 2000 &
    tcpdump -ni ltp_ns_veth2
    ...
    IP (tos 0x0, ttl 64, id 45203, offset 0, flags [+],
      proto Compressed IP (108), length 49)
      10.0.0.2 > 10.0.0.1: IPComp(cpi=0x1000)
    IP (tos 0x0, ttl 64, id 45203, offset 1480, flags [none],
      proto UDP (17), length 21) 10.0.0.2 > 10.0.0.1: ip-proto-17

* IPv6 case, sending small fragments
    udp_ipsec.sh -6 -p comp -m transport -s 2000 &
    tcpdump -ni ltp_ns_veth2
    ...
    IP6 (flowlabel 0x6b9ba, hlim 64, next-header Compressed IP (108)
      payload length: 37) fd00::2 > fd00::1: IPComp(cpi=0x1000)
    IP6 (flowlabel 0x6b9ba, hlim 64, next-header Compressed IP (108)
      payload length: 21) fd00::2 > fd00::1: IPComp(cpi=0x1000)

Fix it by checking 'rt->dst.xfrm' pointer to 'xfrm_state' struct, skip UFO
if xfrm is set. So the new check will include both cases: IPcomp and IPsec.

Fixes: c146066ab802 ("ipv4: Don't use ufo handling on later transformed packets")
Fixes: f89c56ce710a ("ipv6: Don't use ufo handling on later transformed packets")
Signed-off-by: Alexey Kodanev <alexey.kodanev@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
[bwh: Backported to 3.2: adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

diff --git a/net/ipv4/ip_output.c b/net/ipv4/ip_output.c
index 013f59b89e27011864da309063e3e07c43ecc7af..c3a2b805d6f5f3c197843f8278aa6db5d95e979f 100644 (file)
--- a/net/ipv4/ip_output.c
+++ b/net/ipv4/ip_output.c
@@ -834,7 +834,7 @@ static int __ip_append_data(struct sock *sk,
        cork->length += length;
        if (((length > mtu) || (skb && skb_has_frags(skb))) &&
            (sk->sk_protocol == IPPROTO_UDP) &&
-           (rt->dst.dev->features & NETIF_F_UFO) && !rt->dst.header_len &&
+           (rt->dst.dev->features & NETIF_F_UFO) && !dst_xfrm(&rt->dst) &&
            (sk->sk_type == SOCK_DGRAM)) {
                err = ip_ufo_append_data(sk, queue, getfrag, from, length,
                                         hh_len, fragheaderlen, transhdrlen,

diff --git a/net/ipv6/ip6_output.c b/net/ipv6/ip6_output.c
index 4ce3e3f32802c0966862066c9ffa94674adc4335..dd8aca80b6fe403d1b901386e53bf680ef1120ee 100644 (file)
--- a/net/ipv6/ip6_output.c
+++ b/net/ipv6/ip6_output.c
@@ -1343,7 +1343,7 @@ int ip6_append_data(struct sock *sk, int getfrag(void *from, char *to,
        if (((length > mtu) ||
             (skb && skb_has_frags(skb))) &&
            (sk->sk_protocol == IPPROTO_UDP) &&
-           (rt->dst.dev->features & NETIF_F_UFO) && !rt->dst.header_len &&
+           (rt->dst.dev->features & NETIF_F_UFO) && !dst_xfrm(&rt->dst) &&
            (sk->sk_type == SOCK_DGRAM)) {
                err = ip6_ufo_append_data(sk, getfrag, from, length,
                                          hh_len, fragheaderlen, exthdrlen,