[IPSEC]: Move IP length/checksum setting out of transforms

This patch moves the setting of the IP length and checksum fields out of
the transforms and into the xfrmX_output functions.  This would help future
efforts in merging the transforms themselves.

It also adds an optimisation to ipcomp due to the fact that the transport
offset is guaranteed to be zero.

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

1 files changed, 5 insertions, 17 deletions

diff --git a/net/ipv4/ipcomp.c b/net/ipv4/ipcomp.c
index 78d6ddb02d1d..32b02deca2ec 100644
--- a/net/ipv4/ipcomp.c
+++ b/net/ipv4/ipcomp.c
@@ -98,10 +98,9 @@ out:
 static int ipcomp_compress(struct xfrm_state *x, struct sk_buff *skb)
 {
         struct ipcomp_data *ipcd = x->data;
-        const int ihlen = skb_transport_offset(skb);
-        const int plen = skb->len - ihlen;
+        const int plen = skb->len;
         int dlen = IPCOMP_SCRATCH_SIZE;
-        u8 *start = skb_transport_header(skb);
+        u8 *start = skb->data;
         const int cpu = get_cpu();
         u8 *scratch = *per_cpu_ptr(ipcomp_scratches, cpu);
         struct crypto_comp *tfm = *per_cpu_ptr(ipcd->tfms, cpu);
@@ -118,7 +117,7 @@ static int ipcomp_compress(struct xfrm_state *x, struct sk_buff *skb)
         memcpy(start + sizeof(struct ip_comp_hdr), scratch, dlen);
         put_cpu();
 
-        pskb_trim(skb, ihlen + dlen + sizeof(struct ip_comp_hdr));
+        pskb_trim(skb, dlen + sizeof(struct ip_comp_hdr));
         return 0;
 
 out:
@@ -131,13 +130,8 @@ static int ipcomp_output(struct xfrm_state *x, struct sk_buff *skb)
         int err;
         struct ip_comp_hdr *ipch;
         struct ipcomp_data *ipcd = x->data;
-        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) {
+        if (skb->len < ipcd->threshold) {
                 /* Don't bother compressing */
                 goto out_ok;
         }
@@ -146,25 +140,19 @@ static int ipcomp_output(struct xfrm_state *x, struct sk_buff *skb)
                 goto out_ok;
 
         err = ipcomp_compress(x, skb);
-        iph = ip_hdr(skb);
 
         if (err) {
                 goto out_ok;
         }
 
         /* Install ipcomp header, convert into ipcomp datagram. */
-        iph->tot_len = htons(skb->len);
         ipch = ip_comp_hdr(skb);
         ipch->nexthdr = *skb_mac_header(skb);
         ipch->flags = 0;
         ipch->cpi = htons((u16 )ntohl(x->id.spi));
         *skb_mac_header(skb) = IPPROTO_COMP;
-        ip_send_check(iph);
-        return 0;
-
 out_ok:
-        if (x->props.mode == XFRM_MODE_TUNNEL)
-                ip_send_check(iph);
+        skb_push(skb, -skb_network_offset(skb));
         return 0;
 }