[NETFILTER]: nf_conntrack: make l3proto->prepare() generic and renames it

The icmp[v6] l4proto modules parse headers in ICMP[v6] error to get tuple.
But they have to find the offset to transport protocol header before that.
Their processings are almost same as prepare() of l3proto modules.
This makes prepare() more generic to simplify icmp[v6] l4proto module
later.

Signed-off-by: Yasuyuki Kozakai <yasuyuki.kozakai@toshiba.co.jp>
Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 16 insertions, 11 deletions

diff --git a/net/ipv6/netfilter/nf_conntrack_l3proto_ipv6.c b/net/ipv6/netfilter/nf_conntrack_l3proto_ipv6.c
index b5c4bb54691e..9b7eaaadc67e 100644
--- a/net/ipv6/netfilter/nf_conntrack_l3proto_ipv6.c
+++ b/net/ipv6/netfilter/nf_conntrack_l3proto_ipv6.c
@@ -86,7 +86,7 @@ static int ipv6_print_conntrack(struct seq_file *s,
  *        - Note also special handling of AUTH header. Thanks to IPsec wizards.
  */
 
-int nf_ct_ipv6_skip_exthdr(struct sk_buff *skb, int start, u8 *nexthdrp,
+int nf_ct_ipv6_skip_exthdr(const struct sk_buff *skb, int start, u8 *nexthdrp,
                            int len)
 {
         u8 nexthdr = *nexthdrp;
@@ -117,19 +117,24 @@ int nf_ct_ipv6_skip_exthdr(struct sk_buff *skb, int start, u8 *nexthdrp,
         return start;
 }
 
-static int
-ipv6_prepare(struct sk_buff **pskb, unsigned int hooknum, unsigned int *dataoff,
-             u_int8_t *protonum)
+static int ipv6_get_l4proto(const struct sk_buff *skb, unsigned int nhoff,
+                            unsigned int *dataoff, u_int8_t *protonum)
 {
-        unsigned int extoff = (u8 *)(ipv6_hdr(*pskb) + 1) - (*pskb)->data;
-        unsigned char pnum = ipv6_hdr(*pskb)->nexthdr;
-        int protoff = nf_ct_ipv6_skip_exthdr(*pskb, extoff, &pnum,
-                                             (*pskb)->len - extoff);
+        unsigned int extoff = nhoff + sizeof(struct ipv6hdr);
+        unsigned char pnum;
+        int protoff;
+
+        if (skb_copy_bits(skb, nhoff + offsetof(struct ipv6hdr, nexthdr),
+                          &pnum, sizeof(pnum)) != 0) {
+                pr_debug("ip6_conntrack_core: can't get nexthdr\n");
+                return -NF_ACCEPT;
+        }
+        protoff = nf_ct_ipv6_skip_exthdr(skb, extoff, &pnum, skb->len - extoff);
         /*
-         * (protoff == (*pskb)->len) mean that the packet doesn't have no data
+         * (protoff == skb->len) mean that the packet doesn't have no data
          * except of IPv6 & ext headers. but it's tracked anyway. - YK
          */
-        if ((protoff < 0) || (protoff > (*pskb)->len)) {
+        if ((protoff < 0) || (protoff > skb->len)) {
                 pr_debug("ip6_conntrack_core: can't find proto in pkt\n");
                 return -NF_ACCEPT;
         }
@@ -375,7 +380,7 @@ struct nf_conntrack_l3proto nf_conntrack_l3proto_ipv6 = {
         .invert_tuple           = ipv6_invert_tuple,
         .print_tuple            = ipv6_print_tuple,
         .print_conntrack        = ipv6_print_conntrack,
-        .prepare                = ipv6_prepare,
+        .get_l4proto            = ipv6_get_l4proto,
 #if defined(CONFIG_NF_CT_NETLINK) || defined(CONFIG_NF_CT_NETLINK_MODULE)
         .tuple_to_nfattr        = ipv6_tuple_to_nfattr,
         .nfattr_to_tuple        = ipv6_nfattr_to_tuple,