[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>

7 files changed, 11 insertions, 10 deletions

diff --git a/net/ipv4/ah4.c b/net/ipv4/ah4.c
index 3513149..dbb1f11 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 1af332d..0f5e838 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 e787044..1929d45 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 a73e710..77888f5 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 6010471..10499d2 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 9963700..bac1a91 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 9275c79..be572f9 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);