[DCCP]: Retrieve packet sequence number for error reporting

This fixes a problem when analysing erroneous packets in dccp_v{4,6}_err:
* dccp_hdr_seq currently takes an skb
* however, the transport headers in the skb are shifted, due to the
  preceding IPv4/v6 header.
Fixed for v4 and v6 by changing dccp_hdr_seq to take a struct dccp_hdr as
argument. Verified that the correct sequence number is now reported in the
error handler.

Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>
Acked-by: Ian McDonald <ian.mcdonald@jandi.co.nz>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

1 files changed, 4 insertions, 6 deletions

diff --git a/include/linux/dccp.h b/include/linux/dccp.h
index f3fc4392e93d..55d28cb97596 100644
--- a/include/linux/dccp.h
+++ b/include/linux/dccp.h
@@ -270,10 +270,9 @@ static inline struct dccp_hdr *dccp_zeroed_hdr(struct sk_buff *skb, int headlen)
         return memset(skb_transport_header(skb), 0, headlen);
 }
 
-static inline struct dccp_hdr_ext *dccp_hdrx(const struct sk_buff *skb)
+static inline struct dccp_hdr_ext *dccp_hdrx(const struct dccp_hdr *dh)
 {
-        return (struct dccp_hdr_ext *)(skb_transport_header(skb) +
-                                       sizeof(struct dccp_hdr));
+        return (struct dccp_hdr_ext *)((unsigned char *)dh + sizeof(*dh));
 }
 
 static inline unsigned int __dccp_basic_hdr_len(const struct dccp_hdr *dh)
@@ -287,13 +286,12 @@ static inline unsigned int dccp_basic_hdr_len(const struct sk_buff *skb)
         return __dccp_basic_hdr_len(dh);
 }
 
-static inline __u64 dccp_hdr_seq(const struct sk_buff *skb)
+static inline __u64 dccp_hdr_seq(const struct dccp_hdr *dh)
 {
-        const struct dccp_hdr *dh = dccp_hdr(skb);
         __u64 seq_nr =  ntohs(dh->dccph_seq);
 
         if (dh->dccph_x != 0)
-                seq_nr = (seq_nr << 32) + ntohl(dccp_hdrx(skb)->dccph_seq_low);
+                seq_nr = (seq_nr << 32) + ntohl(dccp_hdrx(dh)->dccph_seq_low);
         else
                 seq_nr += (u32)dh->dccph_seq2 << 16;