[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>

4 files changed, 27 insertions, 45 deletions

diff --git a/net/ipv6/ah6.c b/net/ipv6/ah6.c
index 6778173a3dda..d31c0d6c0448 100644
--- a/net/ipv6/ah6.c
+++ b/net/ipv6/ah6.c
@@ -292,7 +292,7 @@ static int ah6_input(struct xfrm_state *x, struct sk_buff *skb)
 
                 memcpy(auth_data, ah->auth_data, ahp->icv_trunc_len);
                 memset(ah->auth_data, 0, ahp->icv_trunc_len);
-                skb_push(skb, skb->data - skb->nh.raw);
+                skb_push(skb, hdr_len);
                 ahp->icv(ahp, skb, ah->auth_data);
                 if (memcmp(ah->auth_data, auth_data, ahp->icv_trunc_len)) {
                         LIMIT_NETDEBUG(KERN_WARNING "ipsec ah authentication error\n");
@@ -301,12 +301,8 @@ static int ah6_input(struct xfrm_state *x, struct sk_buff *skb)
                 }
         }
 
-        skb->nh.raw = skb_pull(skb, ah_hlen);
-        memcpy(skb->nh.raw, tmp_hdr, hdr_len);
-        skb->nh.ipv6h->payload_len = htons(skb->len - sizeof(struct ipv6hdr));
-        skb_pull(skb, hdr_len);
-        skb->h.raw = skb->data;
-
+        skb->h.raw = memcpy(skb->nh.raw += ah_hlen, tmp_hdr, hdr_len);
+        __skb_pull(skb, ah_hlen + hdr_len);
 
         kfree(tmp_hdr);
 
diff --git a/net/ipv6/esp6.c b/net/ipv6/esp6.c
index 22f046079037..a15a6f320f70 100644
--- a/net/ipv6/esp6.c
+++ b/net/ipv6/esp6.c
@@ -142,25 +142,17 @@ static int esp6_input(struct xfrm_state *x, struct sk_buff *skb)
 
         int hdr_len = skb->h.raw - skb->nh.raw;
         int nfrags;
-        unsigned char *tmp_hdr = NULL;
         int ret = 0;
 
         if (!pskb_may_pull(skb, sizeof(struct ipv6_esp_hdr))) {
                 ret = -EINVAL;
-                goto out_nofree;
+                goto out;
         }
 
         if (elen <= 0 || (elen & (blksize-1))) {
                 ret = -EINVAL;
-                goto out_nofree;
-        }
-
-        tmp_hdr = kmalloc(hdr_len, GFP_ATOMIC);
-        if (!tmp_hdr) {
-                ret = -ENOMEM;
-                goto out_nofree;
+                goto out;
         }
-        memcpy(tmp_hdr, skb->nh.raw, hdr_len);
 
         /* If integrity check is required, do this. */
         if (esp->auth.icv_full_len) {
@@ -222,16 +214,12 @@ static int esp6_input(struct xfrm_state *x, struct sk_buff *skb)
                 /* ... check padding bits here. Silly. :-) */ 
 
                 pskb_trim(skb, skb->len - alen - padlen - 2);
-                skb->h.raw = skb_pull(skb, sizeof(struct ipv6_esp_hdr) + esp->conf.ivlen);
-                skb->nh.raw += sizeof(struct ipv6_esp_hdr) + esp->conf.ivlen;
-                memcpy(skb->nh.raw, tmp_hdr, hdr_len);
-                skb->nh.ipv6h->payload_len = htons(skb->len - sizeof(struct ipv6hdr));
                 ret = nexthdr[1];
         }
 
+        skb->h.raw = __skb_pull(skb, sizeof(*esph) + esp->conf.ivlen) - hdr_len;
+
 out:
-        kfree(tmp_hdr);
-out_nofree:
         return ret;
 }
 
diff --git a/net/ipv6/ipcomp6.c b/net/ipv6/ipcomp6.c
index 48636436028a..cec3be544b69 100644
--- a/net/ipv6/ipcomp6.c
+++ b/net/ipv6/ipcomp6.c
@@ -66,10 +66,8 @@ static LIST_HEAD(ipcomp6_tfms_list);
 static int ipcomp6_input(struct xfrm_state *x, struct sk_buff *skb)
 {
         int err = 0;
-        u8 nexthdr = 0;
-        int hdr_len = skb->h.raw - skb->nh.raw;
-        unsigned char *tmp_hdr = NULL;
         struct ipv6hdr *iph;
+        struct ipv6_comp_hdr *ipch;
         int plen, dlen;
         struct ipcomp_data *ipcd = x->data;
         u8 *start, *scratch;
@@ -86,17 +84,9 @@ static int ipcomp6_input(struct xfrm_state *x, struct sk_buff *skb)
 
         /* Remove ipcomp header and decompress original payload */
         iph = skb->nh.ipv6h;
-        tmp_hdr = kmalloc(hdr_len, GFP_ATOMIC);
-        if (!tmp_hdr)
-                goto out;
-        memcpy(tmp_hdr, iph, hdr_len);
-        nexthdr = *(u8 *)skb->data;
-        skb_pull(skb, sizeof(struct ipv6_comp_hdr)); 
-        skb->nh.raw += sizeof(struct ipv6_comp_hdr);
-        memcpy(skb->nh.raw, tmp_hdr, hdr_len);
-        iph = skb->nh.ipv6h;
-        iph->payload_len = htons(ntohs(iph->payload_len) - sizeof(struct ipv6_comp_hdr));
-        skb->h.raw = skb->data;
+        ipch = (void *)skb->data;
+        skb->h.raw = skb->nh.raw + sizeof(*ipch);
+        __skb_pull(skb, sizeof(*ipch));
 
         /* decompression */
         plen = skb->len;
@@ -125,18 +115,11 @@ static int ipcomp6_input(struct xfrm_state *x, struct sk_buff *skb)
 
         skb_put(skb, dlen - plen);
         memcpy(skb->data, scratch, dlen);
+        err = ipch->nexthdr;
 
-        iph = skb->nh.ipv6h;
-        iph->payload_len = htons(skb->len);
-        
 out_put_cpu:
         put_cpu();
 out:
-        kfree(tmp_hdr);
-        if (err)
-                goto error_out;
-        return nexthdr;
-error_out:
         return err;
 }
 
diff --git a/net/ipv6/xfrm6_mode_transport.c b/net/ipv6/xfrm6_mode_transport.c
index 5efbbae08ef0..711d713e36d8 100644
--- a/net/ipv6/xfrm6_mode_transport.c
+++ b/net/ipv6/xfrm6_mode_transport.c
@@ -42,8 +42,23 @@ static int xfrm6_transport_output(struct sk_buff *skb)
         return 0;
 }
 
+/* Remove encapsulation header.
+ *
+ * The IP header will be moved over the top of the encapsulation header.
+ *
+ * On entry, skb->h shall point to where the IP header should be and skb->nh
+ * shall be set to where the IP header currently is.  skb->data shall point
+ * to the start of the payload.
+ */
 static int xfrm6_transport_input(struct xfrm_state *x, struct sk_buff *skb)
 {
+        int ihl = skb->data - skb->h.raw;
+
+        if (skb->h.raw != skb->nh.raw)
+                skb->nh.raw = memmove(skb->h.raw, skb->nh.raw, ihl);
+        skb->nh.ipv6h->payload_len = htons(skb->len + ihl -
+                                           sizeof(struct ipv6hdr));
+        skb->h.raw = skb->data;
         return 0;
 }