When an error occurs skipping IPv6 extension headers retain the already
parsed IP protocol and IPv6 addresses in the flow. Also assume that the
packet is not a fragment in the absence of information to the contrary;
that is always use the frag_off value set by ipv6_skip_exthdr().

This allows matching on the IP protocol and IPv6 addresses of packets
with malformed extension headers.

Signed-off-by: Simon Horman <simon.hor...@netronome.com>

---

* Some consideration should be given to unwanted side effects of this patch
  as it affects the handling of malformed packets.

Signed-off-by: Simon Horman <simon.hor...@netronome.com>
---
 net/openvswitch/flow.c | 11 +++++++----
 1 file changed, 7 insertions(+), 4 deletions(-)

diff --git a/net/openvswitch/flow.c b/net/openvswitch/flow.c
index 8db22ef73626..3c5336c5d4ea 100644
--- a/net/openvswitch/flow.c
+++ b/net/openvswitch/flow.c
@@ -271,8 +271,6 @@ static int parse_ipv6hdr(struct sk_buff *skb, struct 
sw_flow_key *key)
        key->ipv6.addr.dst = nh->daddr;
 
        payload_ofs = ipv6_skip_exthdr(skb, payload_ofs, &nexthdr, &frag_off);
-       if (unlikely(payload_ofs < 0))
-               return -EINVAL;
 
        if (frag_off) {
                if (frag_off & htons(~0x7))
@@ -283,6 +281,13 @@ static int parse_ipv6hdr(struct sk_buff *skb, struct 
sw_flow_key *key)
                key->ip.frag = OVS_FRAG_TYPE_NONE;
        }
 
+       /* Delayed handling of error in ipv6_skip_exthdr() as it
+        * always sets frag_off to a valid value which may be
+        * used to set key->ip.frag above.
+        */
+       if (unlikely(payload_ofs < 0))
+               return -EINVAL;
+
        nh_len = payload_ofs - nh_ofs;
        skb_set_transport_header(skb, nh_ofs + nh_len);
        key->ip.proto = nexthdr;
@@ -622,8 +627,6 @@ static int key_extract(struct sk_buff *skb, struct 
sw_flow_key *key)
 
                nh_len = parse_ipv6hdr(skb, key);
                if (unlikely(nh_len < 0)) {
-                       memset(&key->ip, 0, sizeof(key->ip));
-                       memset(&key->ipv6.addr, 0, sizeof(key->ipv6.addr));
                        if (nh_len == -EINVAL) {
                                skb->transport_header = skb->network_header;
                                error = 0;
-- 
2.1.4

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