[IPSEC]: Use IPv6 calling convention as the convention for x->mode->output

The IPv6 calling convention for x->mode->output is more general and could
help an eventual protocol-generic x->type->output implementation.  This
patch adopts it for IPv4 as well and modifies the IPv4 type output functions
accordingly.

It also rewrites the IPv6 mac/transport header calculation to be based off
the network header where practical.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>

6 files changed, 26 insertions, 32 deletions

diff --git a/net/ipv4/ah4.c b/net/ipv4/ah4.c
index dbb1f11721e4..e4f7aa39978d 100644
--- a/net/ipv4/ah4.c
+++ b/net/ipv4/ah4.c
@@ -82,14 +82,14 @@ static int ah_output(struct xfrm_state *x, struct sk_buff *skb)
                         goto error;
         }
 
-        ah = (struct ip_auth_hdr *)((char *)top_iph+top_iph->ihl*4);
-        ah->nexthdr = top_iph->protocol;
+        ah = (struct ip_auth_hdr *)skb_transport_header(skb);
+        ah->nexthdr = *skb_mac_header(skb);
+        *skb_mac_header(skb) = IPPROTO_AH;
 
         top_iph->tos = 0;
         top_iph->tot_len = htons(skb->len);
         top_iph->frag_off = 0;
         top_iph->ttl = 0;
-        top_iph->protocol = IPPROTO_AH;
         top_iph->check = 0;
 
         ahp = x->data;
diff --git a/net/ipv4/esp4.c b/net/ipv4/esp4.c
index 0f5e8387ccb4..93153d105619 100644
--- a/net/ipv4/esp4.c
+++ b/net/ipv4/esp4.c
@@ -60,10 +60,10 @@ static int esp_output(struct xfrm_state *x, struct sk_buff *skb)
 
         skb_push(skb, -skb_network_offset(skb));
         top_iph = ip_hdr(skb);
-        esph = (struct ip_esp_hdr *)(skb_network_header(skb) +
-                                     top_iph->ihl * 4);
+        esph = (struct ip_esp_hdr *)skb_transport_header(skb);
         top_iph->tot_len = htons(skb->len + alen);
-        *(skb_tail_pointer(trailer) - 1) = top_iph->protocol;
+        *(skb_tail_pointer(trailer) - 1) = *skb_mac_header(skb);
+        *skb_mac_header(skb) = IPPROTO_ESP;
 
         spin_lock_bh(&x->lock);
 
@@ -91,9 +91,8 @@ static int esp_output(struct xfrm_state *x, struct sk_buff *skb)
                         break;
                 }
 
-                top_iph->protocol = IPPROTO_UDP;
-        } else
-                top_iph->protocol = IPPROTO_ESP;
+                *skb_mac_header(skb) = IPPROTO_UDP;
+        }
 
         esph->spi = x->id.spi;
         esph->seq_no = htonl(XFRM_SKB_CB(skb)->seq);
diff --git a/net/ipv4/ipcomp.c b/net/ipv4/ipcomp.c
index 1929d451dab5..bf74f64fe5fb 100644
--- a/net/ipv4/ipcomp.c
+++ b/net/ipv4/ipcomp.c
@@ -98,10 +98,10 @@ out:
 static int ipcomp_compress(struct xfrm_state *x, struct sk_buff *skb)
 {
         struct ipcomp_data *ipcd = x->data;
-        const int ihlen = ip_hdrlen(skb);
+        const int ihlen = skb_transport_offset(skb);
         const int plen = skb->len - ihlen;
         int dlen = IPCOMP_SCRATCH_SIZE;
-        u8 *start = skb->data + ihlen;
+        u8 *start = skb_transport_header(skb);
         const int cpu = get_cpu();
         u8 *scratch = *per_cpu_ptr(ipcomp_scratches, cpu);
         struct crypto_comp *tfm = *per_cpu_ptr(ipcd->tfms, cpu);
@@ -154,11 +154,11 @@ static int ipcomp_output(struct xfrm_state *x, struct sk_buff *skb)
 
         /* Install ipcomp header, convert into ipcomp datagram. */
         iph->tot_len = htons(skb->len);
-        ipch = (struct ip_comp_hdr *)((char *)iph + iph->ihl * 4);
-        ipch->nexthdr = iph->protocol;
+        ipch = (struct ip_comp_hdr *)skb_transport_header(skb);
+        ipch->nexthdr = *skb_mac_header(skb);
         ipch->flags = 0;
         ipch->cpi = htons((u16 )ntohl(x->id.spi));
-        iph->protocol = IPPROTO_COMP;
+        *skb_mac_header(skb) = IPPROTO_COMP;
         ip_send_check(iph);
         return 0;
 
diff --git a/net/ipv4/xfrm4_mode_beet.c b/net/ipv4/xfrm4_mode_beet.c
index 77888f596737..7226c6486c01 100644
--- a/net/ipv4/xfrm4_mode_beet.c
+++ b/net/ipv4/xfrm4_mode_beet.c
@@ -23,17 +23,14 @@
  * The following fields in it shall be filled in by x->type->output:
  *      tot_len
  *      check
- *
- * On exit, skb->h will be set to the start of the payload to be processed
- * by x->type->output and skb->nh will be set to the top IP header.
  */
 static int xfrm4_beet_output(struct xfrm_state *x, struct sk_buff *skb)
 {
+        struct ip_beet_phdr *ph;
         struct iphdr *iph, *top_iph;
         int hdrlen, optlen;
 
         iph = ip_hdr(skb);
-        skb->transport_header = skb->network_header;
 
         hdrlen = 0;
         optlen = iph->ihl * 4 - sizeof(*iph);
@@ -42,17 +39,17 @@ static int xfrm4_beet_output(struct xfrm_state *x, struct sk_buff *skb)
 
         skb_set_network_header(skb, IPV4_BEET_PHMAXLEN - x->props.header_len -
                                     hdrlen);
-        top_iph = ip_hdr(skb);
-        skb->transport_header += sizeof(*iph) - hdrlen;
-        __skb_pull(skb, sizeof(*iph) - hdrlen);
+        skb->mac_header = skb->network_header +
+                          offsetof(struct iphdr, protocol);
+        skb->transport_header = skb->network_header + sizeof(*iph);
+
+        ph = (struct ip_beet_phdr *)__skb_pull(skb, sizeof(*iph) - hdrlen);
 
+        top_iph = ip_hdr(skb);
         memmove(top_iph, iph, sizeof(*iph));
         if (unlikely(optlen)) {
-                struct ip_beet_phdr *ph;
-
                 BUG_ON(optlen < 0);
 
-                ph = (struct ip_beet_phdr *)skb_transport_header(skb);
                 ph->padlen = 4 - (optlen & 4);
                 ph->hdrlen = optlen / 8;
                 ph->nexthdr = top_iph->protocol;
diff --git a/net/ipv4/xfrm4_mode_transport.c b/net/ipv4/xfrm4_mode_transport.c
index 10499d2ec65e..fd840c7d75ea 100644
--- a/net/ipv4/xfrm4_mode_transport.c
+++ b/net/ipv4/xfrm4_mode_transport.c
@@ -17,17 +17,16 @@
  *
  * The IP header will be moved forward to make space for the encapsulation
  * header.
- *
- * On exit, skb->h will be set to the start of the payload to be processed
- * by x->type->output and skb->nh will be set to the top IP header.
  */
 static int xfrm4_transport_output(struct xfrm_state *x, struct sk_buff *skb)
 {
         struct iphdr *iph = ip_hdr(skb);
         int ihl = iph->ihl * 4;
 
-        skb->transport_header = skb->network_header + ihl;
         skb_set_network_header(skb, -x->props.header_len);
+        skb->mac_header = skb->network_header +
+                          offsetof(struct iphdr, protocol);
+        skb->transport_header = skb->network_header + ihl;
         __skb_pull(skb, ihl);
         memmove(skb_network_header(skb), iph, ihl);
         return 0;
diff --git a/net/ipv4/xfrm4_mode_tunnel.c b/net/ipv4/xfrm4_mode_tunnel.c
index bac1a91f0cbe..f1d41ea34785 100644
--- a/net/ipv4/xfrm4_mode_tunnel.c
+++ b/net/ipv4/xfrm4_mode_tunnel.c
@@ -35,9 +35,6 @@ static inline void ipip6_ecn_decapsulate(struct iphdr *iph, struct sk_buff *skb)
  * in it shall be filled in by x->type->output:
  *      tot_len
  *      check
- *
- * On exit, skb->h will be set to the start of the payload to be processed
- * by x->type->output and skb->nh will be set to the top IP header.
  */
 static int xfrm4_tunnel_output(struct xfrm_state *x, struct sk_buff *skb)
 {
@@ -47,9 +44,11 @@ static int xfrm4_tunnel_output(struct xfrm_state *x, struct sk_buff *skb)
         int flags;
 
         iph = ip_hdr(skb);
-        skb->transport_header = skb->network_header;
 
         skb_set_network_header(skb, -x->props.header_len);
+        skb->mac_header = skb->network_header +
+                          offsetof(struct iphdr, protocol);
+        skb->transport_header = skb->network_header + sizeof(*iph);
         top_iph = ip_hdr(skb);
 
         top_iph->ihl = 5;