[IPSEC]: Separate inner/outer mode processing on input

With inter-family transforms the inner mode differs from the outer
mode.  Attempting to handle both sides from the same function means
that it needs to handle both IPv4 and IPv6 which creates duplication
and confusion.

This patch separates the two parts on the input path so that each
function deals with one family only.

In particular, the functions xfrm4_extract_inut/xfrm6_extract_inut
moves the pertinent fields from the IPv4/IPv6 IP headers into a
neutral format stored in skb->cb.  This is then used by the inner mode
input functions to modify the inner IP header.  In this way the input
function no longer has to know about the outer address family.

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

1 files changed, 39 insertions, 28 deletions

diff --git a/net/ipv4/xfrm4_mode_beet.c b/net/ipv4/xfrm4_mode_beet.c
index 94842ad..e093a7b 100644
--- a/net/ipv4/xfrm4_mode_beet.c
+++ b/net/ipv4/xfrm4_mode_beet.c
@@ -17,6 +17,21 @@
 #include <net/ip.h>
 #include <net/xfrm.h>
 
+static void xfrm4_beet_make_header(struct sk_buff *skb)
+{
+	struct iphdr *iph = ip_hdr(skb);
+
+	iph->ihl = 5;
+	iph->version = 4;
+
+	iph->protocol = XFRM_MODE_SKB_CB(skb)->protocol;
+	iph->tos = XFRM_MODE_SKB_CB(skb)->tos;
+
+	iph->id = XFRM_MODE_SKB_CB(skb)->id;
+	iph->frag_off = XFRM_MODE_SKB_CB(skb)->frag_off;
+	iph->ttl = XFRM_MODE_SKB_CB(skb)->ttl;
+}
+
 /* Add encapsulation header.
  *
  * The top IP header will be constructed per draft-nikander-esp-beet-mode-06.txt.
@@ -40,20 +55,12 @@ static int xfrm4_beet_output(struct xfrm_state *x, struct sk_buff *skb)
 			  offsetof(struct iphdr, protocol);
 	skb->transport_header = skb->network_header + sizeof(*iph);
 
+	xfrm4_beet_make_header(skb);
+
 	ph = (struct ip_beet_phdr *)__skb_pull(skb, sizeof(*iph) - hdrlen);
 
 	top_iph = ip_hdr(skb);
 
-	top_iph->ihl = 5;
-	top_iph->version = 4;
-
-	top_iph->protocol = XFRM_MODE_SKB_CB(skb)->protocol;
-	top_iph->tos = XFRM_MODE_SKB_CB(skb)->tos;
-
-	top_iph->id = XFRM_MODE_SKB_CB(skb)->id;
-	top_iph->frag_off = XFRM_MODE_SKB_CB(skb)->frag_off;
-	top_iph->ttl = XFRM_MODE_SKB_CB(skb)->ttl;
-
 	if (unlikely(optlen)) {
 		BUG_ON(optlen < 0);
 
@@ -75,43 +82,46 @@ static int xfrm4_beet_output(struct xfrm_state *x, struct sk_buff *skb)
 
 static int xfrm4_beet_input(struct xfrm_state *x, struct sk_buff *skb)
 {
-	struct iphdr *iph = ip_hdr(skb);
-	int phlen = 0;
+	struct iphdr *iph;
 	int optlen = 0;
-	u8 ph_nexthdr = 0;
 	int err = -EINVAL;
 
-	if (unlikely(iph->protocol == IPPROTO_BEETPH)) {
+	if (unlikely(XFRM_MODE_SKB_CB(skb)->protocol == IPPROTO_BEETPH)) {
 		struct ip_beet_phdr *ph;
+		int phlen;
 
 		if (!pskb_may_pull(skb, sizeof(*ph)))
 			goto out;
-		ph = (struct ip_beet_phdr *)(ipip_hdr(skb) + 1);
+
+		ph = (struct ip_beet_phdr *)skb->data;
 
 		phlen = sizeof(*ph) + ph->padlen;
 		optlen = ph->hdrlen * 8 + (IPV4_BEET_PHMAXLEN - phlen);
 		if (optlen < 0 || optlen & 3 || optlen > 250)
 			goto out;
 
-		if (!pskb_may_pull(skb, phlen + optlen))
-			goto out;
-		skb->len -= phlen + optlen;
+		XFRM_MODE_SKB_CB(skb)->protocol = ph->nexthdr;
 
-		ph_nexthdr = ph->nexthdr;
+		if (!pskb_may_pull(skb, phlen));
+			goto out;
+		__skb_pull(skb, phlen);
 	}
 
-	skb_set_network_header(skb, phlen - sizeof(*iph));
-	memmove(skb_network_header(skb), iph, sizeof(*iph));
-	skb_set_transport_header(skb, phlen + optlen);
-	skb->data = skb_transport_header(skb);
+	skb_push(skb, sizeof(*iph));
+	skb_reset_network_header(skb);
+
+	memmove(skb->data - skb->mac_len, skb_mac_header(skb),
+		skb->mac_len);
+	skb_set_mac_header(skb, -skb->mac_len);
+
+	xfrm4_beet_make_header(skb);
 
 	iph = ip_hdr(skb);
-	iph->ihl = (sizeof(*iph) + optlen) / 4;
-	iph->tot_len = htons(skb->len + iph->ihl * 4);
+
+	iph->ihl += optlen / 4;
+	iph->tot_len = htons(skb->len);
 	iph->daddr = x->sel.daddr.a4;
 	iph->saddr = x->sel.saddr.a4;
-	if (ph_nexthdr)
-		iph->protocol = ph_nexthdr;
 	iph->check = 0;
 	iph->check = ip_fast_csum(skb_network_header(skb), iph->ihl);
 	err = 0;
@@ -120,7 +130,8 @@ out:
 }
 
 static struct xfrm_mode xfrm4_beet_mode = {
-	.input = xfrm4_beet_input,
+	.input2 = xfrm4_beet_input,
+	.input = xfrm_prepare_input,
 	.output2 = xfrm4_beet_output,
 	.output = xfrm4_prepare_output,
 	.owner = THIS_MODULE,