[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>

4 files changed, 57 insertions, 63 deletions

diff --git a/net/ipv4/xfrm4_input.c b/net/ipv4/xfrm4_input.c
index 5e95c8a07efb..c0323d05ab69 100644
--- a/net/ipv4/xfrm4_input.c
+++ b/net/ipv4/xfrm4_input.c
@@ -16,6 +16,11 @@
 #include <net/ip.h>
 #include <net/xfrm.h>
 
+int xfrm4_extract_input(struct xfrm_state *x, struct sk_buff *skb)
+{
+        return xfrm4_extract_header(skb);
+}
+
 #ifdef CONFIG_NETFILTER
 static inline int xfrm4_rcv_encap_finish(struct sk_buff *skb)
 {
@@ -91,7 +96,7 @@ int xfrm4_rcv_encap(struct sk_buff *skb, int nexthdr, __be32 spi,
 
                 xfrm_vec[xfrm_nr++] = x;
 
-                if (x->outer_mode->input(x, skb))
+                if (x->inner_mode->input(x, skb))
                         goto drop;
 
                 if (x->outer_mode->flags & XFRM_MODE_FLAG_TUNNEL) {
diff --git a/net/ipv4/xfrm4_mode_beet.c b/net/ipv4/xfrm4_mode_beet.c
index 94842adce144..e093a7b59e18 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,
diff --git a/net/ipv4/xfrm4_mode_tunnel.c b/net/ipv4/xfrm4_mode_tunnel.c
index cc8bbb274e37..aa335dba8ffa 100644
--- a/net/ipv4/xfrm4_mode_tunnel.c
+++ b/net/ipv4/xfrm4_mode_tunnel.c
@@ -16,19 +16,12 @@
 
 static inline void ipip_ecn_decapsulate(struct sk_buff *skb)
 {
-        struct iphdr *outer_iph = ip_hdr(skb);
         struct iphdr *inner_iph = ipip_hdr(skb);
 
-        if (INET_ECN_is_ce(outer_iph->tos))
+        if (INET_ECN_is_ce(XFRM_MODE_SKB_CB(skb)->tos))
                 IP_ECN_set_ce(inner_iph);
 }
 
-static inline void ipip6_ecn_decapsulate(struct iphdr *iph, struct sk_buff *skb)
-{
-        if (INET_ECN_is_ce(iph->tos))
-                IP6_ECN_set_ce(ipv6_hdr(skb));
-}
-
 /* Add encapsulation header.
  *
  * The top IP header will be constructed per RFC 2401.
@@ -72,20 +65,11 @@ static int xfrm4_tunnel_output(struct xfrm_state *x, struct sk_buff *skb)
 
 static int xfrm4_tunnel_input(struct xfrm_state *x, struct sk_buff *skb)
 {
-        struct iphdr *iph = ip_hdr(skb);
         const unsigned char *old_mac;
         int err = -EINVAL;
 
-        switch (iph->protocol){
-                case IPPROTO_IPIP:
-                        break;
-#if defined(CONFIG_IPV6) || defined (CONFIG_IPV6_MODULE)
-                case IPPROTO_IPV6:
-                        break;
-#endif
-                default:
-                        goto out;
-        }
+        if (XFRM_MODE_SKB_CB(skb)->protocol != IPPROTO_IPIP)
+                goto out;
 
         if (!pskb_may_pull(skb, sizeof(struct iphdr)))
                 goto out;
@@ -94,20 +78,11 @@ static int xfrm4_tunnel_input(struct xfrm_state *x, struct sk_buff *skb)
             (err = pskb_expand_head(skb, 0, 0, GFP_ATOMIC)))
                 goto out;
 
-        iph = ip_hdr(skb);
-        if (iph->protocol == IPPROTO_IPIP) {
-                if (x->props.flags & XFRM_STATE_DECAP_DSCP)
-                        ipv4_copy_dscp(ipv4_get_dsfield(iph), ipip_hdr(skb));
-                if (!(x->props.flags & XFRM_STATE_NOECN))
-                        ipip_ecn_decapsulate(skb);
-        }
-#if defined(CONFIG_IPV6) || defined (CONFIG_IPV6_MODULE)
-        else {
-                if (!(x->props.flags & XFRM_STATE_NOECN))
-                        ipip6_ecn_decapsulate(iph, skb);
-                skb->protocol = htons(ETH_P_IPV6);
-        }
-#endif
+        if (x->props.flags & XFRM_STATE_DECAP_DSCP)
+                ipv4_copy_dscp(XFRM_MODE_SKB_CB(skb)->tos, ipip_hdr(skb));
+        if (!(x->props.flags & XFRM_STATE_NOECN))
+                ipip_ecn_decapsulate(skb);
+
         old_mac = skb_mac_header(skb);
         skb_set_mac_header(skb, -skb->mac_len);
         memmove(skb_mac_header(skb), old_mac, skb->mac_len);
@@ -119,7 +94,8 @@ out:
 }
 
 static struct xfrm_mode xfrm4_tunnel_mode = {
-        .input = xfrm4_tunnel_input,
+        .input2 = xfrm4_tunnel_input,
+        .input = xfrm_prepare_input,
         .output2 = xfrm4_tunnel_output,
         .output = xfrm4_prepare_output,
         .owner = THIS_MODULE,
diff --git a/net/ipv4/xfrm4_state.c b/net/ipv4/xfrm4_state.c
index e6030e74ff65..85f04b7b237f 100644
--- a/net/ipv4/xfrm4_state.c
+++ b/net/ipv4/xfrm4_state.c
@@ -65,10 +65,12 @@ int xfrm4_extract_header(struct sk_buff *skb)
 static struct xfrm_state_afinfo xfrm4_state_afinfo = {
         .family                 = AF_INET,
         .proto                  = IPPROTO_IPIP,
+        .eth_proto              = htons(ETH_P_IP),
         .owner                  = THIS_MODULE,
         .init_flags             = xfrm4_init_flags,
         .init_tempsel           = __xfrm4_init_tempsel,
         .output                 = xfrm4_output,
+        .extract_input          = xfrm4_extract_input,
         .extract_output         = xfrm4_extract_output,
 };