udp: avoid ufo handling on IP payload compression packets

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>

diff --git a/net/ipv4/ip_output.c b/net/ipv4/ip_output.c
index 737ce826d7ecfa040d07d7f8e8d6dedd01ca7330..7a3fd25e8913a99d0fcbb256bc9001f6f1d4dd6f 100644 (file)
--- a/net/ipv4/ip_output.c
+++ b/net/ipv4/ip_output.c
@@ -966,7 +966,7 @@ static int __ip_append_data(struct sock *sk,
        cork->length += length;
        if ((((length + fragheaderlen) > mtu) || (skb && skb_is_gso(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) && !sk->sk_no_check_tx) {
                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 528b3c1f3fdee4314e1c23007ae76333b4af7505..df42096e1f0453ace36bf5749adba12f21e3ee15 100644 (file)
--- a/net/ipv6/ip6_output.c
+++ b/net/ipv6/ip6_output.c
@@ -1385,7 +1385,7 @@ emsgsize:
        if ((((length + fragheaderlen) > mtu) ||
             (skb && skb_is_gso(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) && !udp_get_no_check6_tx(sk)) {
                err = ip6_ufo_append_data(sk, queue, getfrag, from, length,
                                          hh_len, fragheaderlen, exthdrlen,