[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, 5 insertions, 18 deletions

diff --git a/net/ipv4/ipcomp.c b/net/ipv4/ipcomp.c
index 95278b22b669..8e243589045f 100644
--- a/net/ipv4/ipcomp.c
+++ b/net/ipv4/ipcomp.c
@@ -45,7 +45,6 @@ static LIST_HEAD(ipcomp_tfms_list);
 static int ipcomp_decompress(struct xfrm_state *x, struct sk_buff *skb)
 {
         int err, plen, dlen;
-        struct iphdr *iph;
         struct ipcomp_data *ipcd = x->data;
         u8 *start, *scratch;
         struct crypto_tfm *tfm;
@@ -74,8 +73,6 @@ static int ipcomp_decompress(struct xfrm_state *x, struct sk_buff *skb)
                 
         skb_put(skb, dlen - plen);
         memcpy(skb->data, scratch, dlen);
-        iph = skb->nh.iph;
-        iph->tot_len = htons(dlen + iph->ihl * 4);
 out:    
         put_cpu();
         return err;
@@ -83,14 +80,9 @@ out:
 
 static int ipcomp_input(struct xfrm_state *x, struct sk_buff *skb)
 {
-        u8 nexthdr;
         int err = 0;
         struct iphdr *iph;
-        union {
-                struct iphdr    iph;
-                char            buf[60];
-        } tmp_iph;
-
+        struct ip_comp_hdr *ipch;
 
         if ((skb_is_nonlinear(skb) || skb_cloned(skb)) &&
             skb_linearize(skb, GFP_ATOMIC) != 0) {
@@ -102,15 +94,10 @@ static int ipcomp_input(struct xfrm_state *x, struct sk_buff *skb)
 
         /* Remove ipcomp header and decompress original payload */      
         iph = skb->nh.iph;
-        memcpy(&tmp_iph, iph, iph->ihl * 4);
-        nexthdr = *(u8 *)skb->data;
-        skb_pull(skb, sizeof(struct ip_comp_hdr));
-        skb->nh.raw += sizeof(struct ip_comp_hdr);
-        memcpy(skb->nh.raw, &tmp_iph, tmp_iph.iph.ihl * 4);
-        iph = skb->nh.iph;
-        iph->tot_len = htons(ntohs(iph->tot_len) - sizeof(struct ip_comp_hdr));
-        iph->protocol = nexthdr;
-        skb->h.raw = skb->data;
+        ipch = (void *)skb->data;
+        iph->protocol = ipch->nexthdr;
+        skb->h.raw = skb->nh.raw + sizeof(*ipch);
+        __skb_pull(skb, sizeof(*ipch));
         err = ipcomp_decompress(x, skb);
 
 out: