[IPSEC]: Set skb->data to payload in x->mode->output

This patch changes the calling convention so that on entry from
x->mode->output and before entry into x->type->output skb->data
will point to the payload instead of the IP header.

This is essentially a redistribution of skb_push/skb_pull calls
with the aim of minimising them on the common path of tunnel +
ESP.

It'll also let us use the same calling convention between IPv4
and IPv6 with the next patch.

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

16 files changed, 47 insertions, 42 deletions

diff --git a/net/ipv4/ah4.c b/net/ipv4/ah4.c
index 3513149c3843..dbb1f11721e4 100644
--- a/net/ipv4/ah4.c
+++ b/net/ipv4/ah4.c
@@ -66,6 +66,7 @@ static int ah_output(struct xfrm_state *x, struct sk_buff *skb)
                 char            buf[60];
         } tmp_iph;
 
+        skb_push(skb, -skb_network_offset(skb));
         top_iph = ip_hdr(skb);
         iph = &tmp_iph.iph;
 
diff --git a/net/ipv4/esp4.c b/net/ipv4/esp4.c
index 1af332df72d9..0f5e8387ccb4 100644
--- a/net/ipv4/esp4.c
+++ b/net/ipv4/esp4.c
@@ -28,9 +28,7 @@ static int esp_output(struct xfrm_state *x, struct sk_buff *skb)
         int alen;
         int nfrags;
 
-        /* Strip IP+ESP header. */
-        __skb_pull(skb, skb_transport_offset(skb));
-        /* Now skb is pure payload to encrypt */
+        /* skb is pure payload to encrypt */
 
         err = -ENOMEM;
 
@@ -60,7 +58,7 @@ static int esp_output(struct xfrm_state *x, struct sk_buff *skb)
         tail[clen - skb->len - 2] = (clen - skb->len) - 2;
         pskb_put(skb, trailer, clen - skb->len);
 
-        __skb_push(skb, -skb_network_offset(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);
diff --git a/net/ipv4/ipcomp.c b/net/ipv4/ipcomp.c
index e787044a8514..1929d451dab5 100644
--- a/net/ipv4/ipcomp.c
+++ b/net/ipv4/ipcomp.c
@@ -134,6 +134,7 @@ static int ipcomp_output(struct xfrm_state *x, struct sk_buff *skb)
         int hdr_len = 0;
         struct iphdr *iph = ip_hdr(skb);
 
+        skb_push(skb, -skb_network_offset(skb));
         iph->tot_len = htons(skb->len);
         hdr_len = iph->ihl * 4;
         if ((skb->len - hdr_len) < ipcd->threshold) {
diff --git a/net/ipv4/xfrm4_mode_beet.c b/net/ipv4/xfrm4_mode_beet.c
index a73e710740c2..77888f596737 100644
--- a/net/ipv4/xfrm4_mode_beet.c
+++ b/net/ipv4/xfrm4_mode_beet.c
@@ -40,10 +40,11 @@ static int xfrm4_beet_output(struct xfrm_state *x, struct sk_buff *skb)
         if (unlikely(optlen))
                 hdrlen += IPV4_BEET_PHMAXLEN - (optlen & 4);
 
-        skb_push(skb, x->props.header_len - IPV4_BEET_PHMAXLEN + hdrlen);
-        skb_reset_network_header(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);
 
         memmove(top_iph, iph, sizeof(*iph));
         if (unlikely(optlen)) {
diff --git a/net/ipv4/xfrm4_mode_transport.c b/net/ipv4/xfrm4_mode_transport.c
index 601047161ea6..10499d2ec65e 100644
--- a/net/ipv4/xfrm4_mode_transport.c
+++ b/net/ipv4/xfrm4_mode_transport.c
@@ -27,8 +27,8 @@ static int xfrm4_transport_output(struct xfrm_state *x, struct sk_buff *skb)
         int ihl = iph->ihl * 4;
 
         skb->transport_header = skb->network_header + ihl;
-        skb_push(skb, x->props.header_len);
-        skb_reset_network_header(skb);
+        skb_set_network_header(skb, -x->props.header_len);
+        __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 9963700e74c1..bac1a91f0cbe 100644
--- a/net/ipv4/xfrm4_mode_tunnel.c
+++ b/net/ipv4/xfrm4_mode_tunnel.c
@@ -49,8 +49,7 @@ static int xfrm4_tunnel_output(struct xfrm_state *x, struct sk_buff *skb)
         iph = ip_hdr(skb);
         skb->transport_header = skb->network_header;
 
-        skb_push(skb, x->props.header_len);
-        skb_reset_network_header(skb);
+        skb_set_network_header(skb, -x->props.header_len);
         top_iph = ip_hdr(skb);
 
         top_iph->ihl = 5;
diff --git a/net/ipv4/xfrm4_tunnel.c b/net/ipv4/xfrm4_tunnel.c
index 9275c79119b6..be572f918b5e 100644
--- a/net/ipv4/xfrm4_tunnel.c
+++ b/net/ipv4/xfrm4_tunnel.c
@@ -14,6 +14,7 @@ static int ipip_output(struct xfrm_state *x, struct sk_buff *skb)
 {
         struct iphdr *iph = ip_hdr(skb);
 
+        skb_push(skb, -skb_network_offset(skb));
         iph->tot_len = htons(skb->len);
         ip_send_check(iph);
 
diff --git a/net/ipv6/ah6.c b/net/ipv6/ah6.c
index c51d77564b44..ac6bae17a13b 100644
--- a/net/ipv6/ah6.c
+++ b/net/ipv6/ah6.c
@@ -236,6 +236,7 @@ static int ah6_output(struct xfrm_state *x, struct sk_buff *skb)
                 char hdrs[0];
         } *tmp_ext;
 
+        skb_push(skb, -skb_network_offset(skb));
         top_iph = ipv6_hdr(skb);
         top_iph->payload_len = htons(skb->len - sizeof(*top_iph));
 
diff --git a/net/ipv6/esp6.c b/net/ipv6/esp6.c
index 7355bb0345e2..21c93f026dbc 100644
--- a/net/ipv6/esp6.c
+++ b/net/ipv6/esp6.c
@@ -54,13 +54,8 @@ static int esp6_output(struct xfrm_state *x, struct sk_buff *skb)
         int nfrags;
         u8 *tail;
         struct esp_data *esp = x->data;
-        int hdr_len = (skb_transport_offset(skb) +
-                       sizeof(*esph) + esp->conf.ivlen);
 
-        /* Strip IP+ESP header. */
-        __skb_pull(skb, hdr_len);
-
-        /* Now skb is pure payload to encrypt */
+        /* skb is pure payload to encrypt */
         err = -ENOMEM;
 
         /* Round to block size */
@@ -89,7 +84,7 @@ static int esp6_output(struct xfrm_state *x, struct sk_buff *skb)
         tail[clen-skb->len - 2] = (clen - skb->len) - 2;
         pskb_put(skb, trailer, clen - skb->len);
 
-        __skb_push(skb, -skb_network_offset(skb));
+        skb_push(skb, -skb_network_offset(skb));
         top_iph = ipv6_hdr(skb);
         esph = (struct ipv6_esp_hdr *)skb_transport_header(skb);
         top_iph->payload_len = htons(skb->len + alen - sizeof(*top_iph));
diff --git a/net/ipv6/ipcomp6.c b/net/ipv6/ipcomp6.c
index 71a14c09975c..87e6407ebf97 100644
--- a/net/ipv6/ipcomp6.c
+++ b/net/ipv6/ipcomp6.c
@@ -128,7 +128,10 @@ static int ipcomp6_output(struct xfrm_state *x, struct sk_buff *skb)
         u8 *start, *scratch;
         struct crypto_comp *tfm;
         int cpu;
-        int hdr_len = skb_transport_offset(skb);
+        int hdr_len;
+
+        skb_push(skb, -skb_network_offset(skb));
+        hdr_len = skb_transport_offset(skb);
 
         /* check whether datagram len is larger than threshold */
         if ((skb->len - hdr_len) < ipcd->threshold) {
diff --git a/net/ipv6/mip6.c b/net/ipv6/mip6.c
index 6475baca63d2..0e7a60f7393a 100644
--- a/net/ipv6/mip6.c
+++ b/net/ipv6/mip6.c
@@ -153,6 +153,7 @@ static int mip6_destopt_output(struct xfrm_state *x, struct sk_buff *skb)
         u8 nexthdr;
         int len;
 
+        skb_push(skb, -skb_network_offset(skb));
         iph = ipv6_hdr(skb);
         iph->payload_len = htons(skb->len - sizeof(*iph));
 
@@ -367,6 +368,7 @@ static int mip6_rthdr_output(struct xfrm_state *x, struct sk_buff *skb)
         struct rt2_hdr *rt2;
         u8 nexthdr;
 
+        skb_push(skb, -skb_network_offset(skb));
         iph = ipv6_hdr(skb);
         iph->payload_len = htons(skb->len - sizeof(*iph));
 
diff --git a/net/ipv6/xfrm6_mode_beet.c b/net/ipv6/xfrm6_mode_beet.c
index d9366dfbf868..bca018d19ec6 100644
--- a/net/ipv6/xfrm6_mode_beet.c
+++ b/net/ipv6/xfrm6_mode_beet.c
@@ -29,8 +29,8 @@
  * filled in by x->type->output and the mac header will be set to the
  * nextheader field of the extension header directly preceding the
  * encapsulation header, or in its absence, that of the top IP header.
- * The value of skb->data and the network header will always point to the
- * top IP header.
+ * The value of the network header will always point to the top IP header
+ * while skb->data will point to the payload.
  */
 static int xfrm6_beet_output(struct xfrm_state *x, struct sk_buff *skb)
 {
@@ -38,16 +38,17 @@ static int xfrm6_beet_output(struct xfrm_state *x, struct sk_buff *skb)
         u8 *prevhdr;
         int hdr_len;
 
-        skb_push(skb, x->props.header_len);
         iph = ipv6_hdr(skb);
 
         hdr_len = ip6_find_1stfragopt(skb, &prevhdr);
-        memmove(skb->data, iph, hdr_len);
 
         skb_set_mac_header(skb, (prevhdr - x->props.header_len) - skb->data);
-        skb_reset_network_header(skb);
-        skb_set_transport_header(skb, hdr_len);
+        skb_set_network_header(skb, -x->props.header_len);
+        skb_set_transport_header(skb, hdr_len - x->props.header_len);
+        __skb_pull(skb, hdr_len);
+
         top_iph = ipv6_hdr(skb);
+        memmove(top_iph, iph, hdr_len);
 
         ipv6_addr_copy(&top_iph->saddr, (struct in6_addr *)&x->props.saddr);
         ipv6_addr_copy(&top_iph->daddr, (struct in6_addr *)&x->id.daddr);
diff --git a/net/ipv6/xfrm6_mode_ro.c b/net/ipv6/xfrm6_mode_ro.c
index 25758048af54..5c29b367b432 100644
--- a/net/ipv6/xfrm6_mode_ro.c
+++ b/net/ipv6/xfrm6_mode_ro.c
@@ -42,8 +42,8 @@
  * filled in by x->type->output and the mac header will be set to the
  * nextheader field of the extension header directly preceding the
  * encapsulation header, or in its absence, that of the top IP header.
- * The value of skb->data and the network header will always point to the
- * top IP header.
+ * The value of the network header will always point to the top IP header
+ * while skb->data will point to the payload.
  */
 static int xfrm6_ro_output(struct xfrm_state *x, struct sk_buff *skb)
 {
@@ -51,14 +51,14 @@ static int xfrm6_ro_output(struct xfrm_state *x, struct sk_buff *skb)
         u8 *prevhdr;
         int hdr_len;
 
-        skb_push(skb, x->props.header_len);
         iph = ipv6_hdr(skb);
 
         hdr_len = x->type->hdr_offset(x, skb, &prevhdr);
         skb_set_mac_header(skb, (prevhdr - x->props.header_len) - skb->data);
-        skb_reset_network_header(skb);
-        skb_set_transport_header(skb, hdr_len);
-        memmove(skb->data, iph, hdr_len);
+        skb_set_network_header(skb, -x->props.header_len);
+        skb_set_transport_header(skb, hdr_len - x->props.header_len);
+        __skb_pull(skb, hdr_len);
+        memmove(ipv6_hdr(skb), iph, hdr_len);
 
         x->lastused = get_seconds();
 
diff --git a/net/ipv6/xfrm6_mode_transport.c b/net/ipv6/xfrm6_mode_transport.c
index 65c166b5d72c..f2ee186494ed 100644
--- a/net/ipv6/xfrm6_mode_transport.c
+++ b/net/ipv6/xfrm6_mode_transport.c
@@ -23,8 +23,8 @@
  * filled in by x->type->output and the mac header will be set to the
  * nextheader field of the extension header directly preceding the
  * encapsulation header, or in its absence, that of the top IP header.
- * The value of skb->data and the network header will always point to the
- * top IP header.
+ * The value of the network header will always point to the top IP header
+ * while skb->data will point to the payload.
  */
 static int xfrm6_transport_output(struct xfrm_state *x, struct sk_buff *skb)
 {
@@ -32,14 +32,14 @@ static int xfrm6_transport_output(struct xfrm_state *x, struct sk_buff *skb)
         u8 *prevhdr;
         int hdr_len;
 
-        skb_push(skb, x->props.header_len);
         iph = ipv6_hdr(skb);
 
         hdr_len = x->type->hdr_offset(x, skb, &prevhdr);
         skb_set_mac_header(skb, (prevhdr - x->props.header_len) - skb->data);
-        skb_reset_network_header(skb);
-        skb_set_transport_header(skb, hdr_len);
-        memmove(skb->data, iph, hdr_len);
+        skb_set_network_header(skb, -x->props.header_len);
+        skb_set_transport_header(skb, hdr_len - x->props.header_len);
+        __skb_pull(skb, hdr_len);
+        memmove(ipv6_hdr(skb), iph, hdr_len);
         return 0;
 }
 
diff --git a/net/ipv6/xfrm6_mode_tunnel.c b/net/ipv6/xfrm6_mode_tunnel.c
index 3dd40af75e81..01bd7d11ea1b 100644
--- a/net/ipv6/xfrm6_mode_tunnel.c
+++ b/net/ipv6/xfrm6_mode_tunnel.c
@@ -41,8 +41,8 @@ static inline void ip6ip_ecn_decapsulate(struct sk_buff *skb)
  * filled in by x->type->output and the mac header will be set to the
  * nextheader field of the extension header directly preceding the
  * encapsulation header, or in its absence, that of the top IP header.
- * The value of skb->data and the network header will always point to the
- * top IP header.
+ * The value of the network header will always point to the top IP header
+ * while skb->data will point to the payload.
  */
 static int xfrm6_tunnel_output(struct xfrm_state *x, struct sk_buff *skb)
 {
@@ -51,12 +51,13 @@ static int xfrm6_tunnel_output(struct xfrm_state *x, struct sk_buff *skb)
         struct ipv6hdr *iph, *top_iph;
         int dsfield;
 
-        skb_push(skb, x->props.header_len);
         iph = ipv6_hdr(skb);
 
-        skb_set_mac_header(skb, offsetof(struct ipv6hdr, nexthdr));
-        skb_reset_network_header(skb);
-        skb_set_transport_header(skb, sizeof(struct ipv6hdr));
+        skb_set_mac_header(skb, offsetof(struct ipv6hdr, nexthdr) -
+                                x->props.header_len);
+        skb_set_network_header(skb, -x->props.header_len);
+        skb_set_transport_header(skb, sizeof(struct ipv6hdr) -
+                                      x->props.header_len);
         top_iph = ipv6_hdr(skb);
 
         top_iph->version = 6;
diff --git a/net/ipv6/xfrm6_tunnel.c b/net/ipv6/xfrm6_tunnel.c
index aeb06076fdd0..00a1a3e5237c 100644
--- a/net/ipv6/xfrm6_tunnel.c
+++ b/net/ipv6/xfrm6_tunnel.c
@@ -244,6 +244,7 @@ static int xfrm6_tunnel_output(struct xfrm_state *x, struct sk_buff *skb)
 {
         struct ipv6hdr *top_iph;
 
+        skb_push(skb, -skb_network_offset(skb));
         top_iph = ipv6_hdr(skb);
         top_iph->payload_len = htons(skb->len - sizeof(struct ipv6hdr));