[IPSEC] proto: Move transport mode input path into xfrm_mode_transport

Now that we have xfrm_mode objects we can move the transport mode specific
input decapsulation code into xfrm_mode_transport.  This removes duplicate
code as well as unnecessary header movement in case of tunnel mode SAs
since we will discard the original IP header immediately.

This also fixes a minor bug for transport-mode ESP where the IP payload
length is set to the correct value minus the header length (with extension
headers for IPv6).

Of course the other neat thing is that we no longer have to allocate
temporary buffers to hold the IP headers for ESP and IPComp.

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

1 files changed, 6 insertions, 12 deletions

diff --git a/net/ipv4/esp4.c b/net/ipv4/esp4.c
index 9d1881c07a32..9bbdd4494551 100644
--- a/net/ipv4/esp4.c
+++ b/net/ipv4/esp4.c
@@ -143,10 +143,9 @@ static int esp_input(struct xfrm_state *x, struct sk_buff *skb)
         int alen = esp->auth.icv_trunc_len;
         int elen = skb->len - sizeof(struct ip_esp_hdr) - esp->conf.ivlen - alen;
         int nfrags;
-        int encap_len = 0;
+        int ihl;
         u8 nexthdr[2];
         struct scatterlist *sg;
-        u8 workbuf[60];
         int padlen;
 
         if (!pskb_may_pull(skb, sizeof(struct ip_esp_hdr)))
@@ -177,7 +176,6 @@ static int esp_input(struct xfrm_state *x, struct sk_buff *skb)
         skb->ip_summed = CHECKSUM_NONE;
 
         esph = (struct ip_esp_hdr*)skb->data;
-        iph = skb->nh.iph;
 
         /* Get ivec. This can be wrong, check against another impls. */
         if (esp->conf.ivlen)
@@ -204,12 +202,12 @@ static int esp_input(struct xfrm_state *x, struct sk_buff *skb)
 
         /* ... check padding bits here. Silly. :-) */ 
 
+        iph = skb->nh.iph;
+        ihl = iph->ihl * 4;
+
         if (x->encap) {
                 struct xfrm_encap_tmpl *encap = x->encap;
-                struct udphdr *uh;
-
-                uh = (struct udphdr *)(iph + 1);
-                encap_len = (void*)esph - (void*)uh;
+                struct udphdr *uh = (void *)(skb->nh.raw + ihl);
 
                 /*
                  * 1) if the NAT-T peer's IP or port changed then
@@ -246,11 +244,7 @@ static int esp_input(struct xfrm_state *x, struct sk_buff *skb)
 
         iph->protocol = nexthdr[1];
         pskb_trim(skb, skb->len - alen - padlen - 2);
-        memcpy(workbuf, skb->nh.raw, iph->ihl*4);
-        skb->h.raw = skb_pull(skb, sizeof(struct ip_esp_hdr) + esp->conf.ivlen);
-        skb->nh.raw += encap_len + sizeof(struct ip_esp_hdr) + esp->conf.ivlen;
-        memcpy(skb->nh.raw, workbuf, iph->ihl*4);
-        skb->nh.iph->tot_len = htons(skb->len);
+        skb->h.raw = __skb_pull(skb, sizeof(*esph) + esp->conf.ivlen) - ihl;
 
         return 0;