[SK_BUFF]: Introduce skb_network_header()

For the places where we need a pointer to the network header, it is still legal
to touch skb->nh.raw directly if just adding to, subtracting from or setting it
to another layer header.

Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 17 insertions, 12 deletions

diff --git a/net/ipv6/mip6.c b/net/ipv6/mip6.c
index 0afcabdd8ed6..bb4033553f3b 100644
--- a/net/ipv6/mip6.c
+++ b/net/ipv6/mip6.c
@@ -99,14 +99,16 @@ int mip6_mh_filter(struct sock *sk, struct sk_buff *skb)
         if (mh->ip6mh_hdrlen < mip6_mh_len(mh->ip6mh_type)) {
                 LIMIT_NETDEBUG(KERN_DEBUG "mip6: MH message too short: %d vs >=%d\n",
                                mh->ip6mh_hdrlen, mip6_mh_len(mh->ip6mh_type));
-                mip6_param_prob(skb, 0, (&mh->ip6mh_hdrlen) - skb->nh.raw);
+                mip6_param_prob(skb, 0, ((&mh->ip6mh_hdrlen) -
+                                         skb_network_header(skb)));
                 return -1;
         }
 
         if (mh->ip6mh_proto != IPPROTO_NONE) {
                 LIMIT_NETDEBUG(KERN_DEBUG "mip6: MH invalid payload proto = %d\n",
                                mh->ip6mh_proto);
-                mip6_param_prob(skb, 0, (&mh->ip6mh_proto) - skb->nh.raw);
+                mip6_param_prob(skb, 0, ((&mh->ip6mh_proto) -
+                                         skb_network_header(skb)));
                 return -1;
         }
 
@@ -152,8 +154,8 @@ static int mip6_destopt_output(struct xfrm_state *x, struct sk_buff *skb)
         iph = (struct ipv6hdr *)skb->data;
         iph->payload_len = htons(skb->len - sizeof(*iph));
 
-        nexthdr = *skb->nh.raw;
-        *skb->nh.raw = IPPROTO_DSTOPTS;
+        nexthdr = *skb_network_header(skb);
+        *skb_network_header(skb) = IPPROTO_DSTOPTS;
 
         dstopt = (struct ipv6_destopt_hdr *)skb->h.raw;
         dstopt->nexthdr = nexthdr;
@@ -215,7 +217,8 @@ static int mip6_destopt_reject(struct xfrm_state *x, struct sk_buff *skb, struct
         if (likely(opt->dsthao)) {
                 offset = ipv6_find_tlv(skb, opt->dsthao, IPV6_TLV_HAO);
                 if (likely(offset >= 0))
-                        hao = (struct ipv6_destopt_hao *)(skb->nh.raw + offset);
+                        hao = (struct ipv6_destopt_hao *)
+                                        (skb_network_header(skb) + offset);
         }
 
         skb_get_timestamp(skb, &stamp);
@@ -254,7 +257,8 @@ static int mip6_destopt_offset(struct xfrm_state *x, struct sk_buff *skb,
 {
         u16 offset = sizeof(struct ipv6hdr);
         struct ipv6_opt_hdr *exthdr = (struct ipv6_opt_hdr*)(skb->nh.ipv6h + 1);
-        unsigned int packet_len = skb->tail - skb->nh.raw;
+        const unsigned char *nh = skb_network_header(skb);
+        unsigned int packet_len = skb->tail - nh;
         int found_rhdr = 0;
 
         *nexthdr = &skb->nh.ipv6h->nexthdr;
@@ -288,7 +292,7 @@ static int mip6_destopt_offset(struct xfrm_state *x, struct sk_buff *skb,
 
                 offset += ipv6_optlen(exthdr);
                 *nexthdr = &exthdr->nexthdr;
-                exthdr = (struct ipv6_opt_hdr*)(skb->nh.raw + offset);
+                exthdr = (struct ipv6_opt_hdr *)(nh + offset);
         }
 
         return offset;
@@ -361,8 +365,8 @@ static int mip6_rthdr_output(struct xfrm_state *x, struct sk_buff *skb)
         iph = (struct ipv6hdr *)skb->data;
         iph->payload_len = htons(skb->len - sizeof(*iph));
 
-        nexthdr = *skb->nh.raw;
-        *skb->nh.raw = IPPROTO_ROUTING;
+        nexthdr = *skb_network_header(skb);
+        *skb_network_header(skb) = IPPROTO_ROUTING;
 
         rt2 = (struct rt2_hdr *)skb->h.raw;
         rt2->rt_hdr.nexthdr = nexthdr;
@@ -384,7 +388,8 @@ static int mip6_rthdr_offset(struct xfrm_state *x, struct sk_buff *skb,
 {
         u16 offset = sizeof(struct ipv6hdr);
         struct ipv6_opt_hdr *exthdr = (struct ipv6_opt_hdr*)(skb->nh.ipv6h + 1);
-        unsigned int packet_len = skb->tail - skb->nh.raw;
+        const unsigned char *nh = skb_network_header(skb);
+        unsigned int packet_len = skb->tail - nh;
         int found_rhdr = 0;
 
         *nexthdr = &skb->nh.ipv6h->nexthdr;
@@ -397,7 +402,7 @@ static int mip6_rthdr_offset(struct xfrm_state *x, struct sk_buff *skb,
                 case NEXTHDR_ROUTING:
                         if (offset + 3 <= packet_len) {
                                 struct ipv6_rt_hdr *rt;
-                                rt = (struct ipv6_rt_hdr *)(skb->nh.raw + offset);
+                                rt = (struct ipv6_rt_hdr *)(nh + offset);
                                 if (rt->type != 0)
                                         return offset;
                         }
@@ -417,7 +422,7 @@ static int mip6_rthdr_offset(struct xfrm_state *x, struct sk_buff *skb,
 
                 offset += ipv6_optlen(exthdr);
                 *nexthdr = &exthdr->nexthdr;
-                exthdr = (struct ipv6_opt_hdr*)(skb->nh.raw + offset);
+                exthdr = (struct ipv6_opt_hdr *)(nh + offset);
         }
 
         return offset;