[PATCH 12/15] esp6: calculate transport_header correctly when sel.family != AF_INET6

[Steffen Klassert]

From: Xin Long <lucien....@gmail.com>

In esp6_init_state() for beet mode when x->sel.family != AF_INET6:

  x->props.header_len = sizeof(struct ip_esp_hdr) +
     crypto_aead_ivsize(aead) + IPV4_BEET_PHMAXLEN +
     (sizeof(struct ipv6hdr) - sizeof(struct iphdr))

In xfrm6_beet_gso_segment() skb->transport_header is supposed to move
to the end of the ph header for IPPROTO_BEETPH, so if x->sel.family !=
AF_INET6 and it's IPPROTO_BEETPH, it should do:

   skb->transport_header -=
      (sizeof(struct ipv6hdr) - sizeof(struct iphdr));
   skb->transport_header += ph->hdrlen * 8;

And IPV4_BEET_PHMAXLEN is only reserved for PH header, so if
x->sel.family != AF_INET6 and it's not IPPROTO_BEETPH, it should do:

   skb->transport_header -=
      (sizeof(struct ipv6hdr) - sizeof(struct iphdr));
   skb->transport_header -= IPV4_BEET_PHMAXLEN;

Thanks Sabrina for looking deep into this issue.

Fixes: 7f9e40eb18a9 ("esp6: add gso_segment for esp6 beet mode")
Reported-by: Sabrina Dubroca <s...@queasysnail.net>
Signed-off-by: Xin Long <lucien....@gmail.com>
Signed-off-by: Steffen Klassert <steffen.klass...@secunet.com>
---
 net/ipv6/esp6_offload.c | 27 +++++++++++++++------------
 1 file changed, 15 insertions(+), 12 deletions(-)

diff --git a/net/ipv6/esp6_offload.c b/net/ipv6/esp6_offload.c
index 9c03460b2760..ab0eea336c70 100644
--- a/net/ipv6/esp6_offload.c
+++ b/net/ipv6/esp6_offload.c
@@ -175,24 +175,27 @@ static struct sk_buff *xfrm6_beet_gso_segment(struct 
xfrm_state *x,
 
        skb->transport_header += x->props.header_len;
 
-       if (proto == IPPROTO_BEETPH) {
-               struct ip_beet_phdr *ph = (struct ip_beet_phdr *)skb->data;
+       if (x->sel.family != AF_INET6) {
+               skb->transport_header -=
+                       (sizeof(struct ipv6hdr) - sizeof(struct iphdr));
 
-               skb->transport_header += ph->hdrlen * 8;
-               proto = ph->nexthdr;
-       }
+               if (proto == IPPROTO_BEETPH) {
+                       struct ip_beet_phdr *ph =
+                               (struct ip_beet_phdr *)skb->data;
+
+                       skb->transport_header += ph->hdrlen * 8;
+                       proto = ph->nexthdr;
+               } else {
+                       skb->transport_header -= IPV4_BEET_PHMAXLEN;
+               }
 
-       if (x->sel.family == AF_INET6) {
+               if (proto == IPPROTO_TCP)
+                       skb_shinfo(skb)->gso_type |= SKB_GSO_TCPV6;
+       } else {
                __be16 frag;
 
                skb->transport_header +=
                        ipv6_skip_exthdr(skb, 0, &proto, &frag);
-       } else {
-               skb->transport_header -=
-                       (sizeof(struct ipv6hdr) - sizeof(struct iphdr));
-
-               if (proto == IPPROTO_TCP)
-                       skb_shinfo(skb)->gso_type |= SKB_GSO_TCPV6;
        }
 
        __skb_pull(skb, skb_transport_offset(skb));
-- 
2.17.1