[IPSEC]: Forbid BEET + ipcomp for now

While BEET can theoretically work with IPComp the current code can't
do that because it tries to construct a BEET mode tunnel type which
doesn't (and cannot) exist.  In fact as it is it won't even attach a
tunnel object at all for BEET which is bogus.

To support this fully we'd also need to change the policy checks on
input to recognise a plain tunnel as a legal variant of an optional
BEET transform.

This patch simply fails such constructions for now.

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

1 files changed, 12 insertions, 8 deletions

diff --git a/net/ipv4/ipcomp.c b/net/ipv4/ipcomp.c
index 2c44a94c2135..f4af99ad8fdb 100644
--- a/net/ipv4/ipcomp.c
+++ b/net/ipv4/ipcomp.c
@@ -182,7 +182,6 @@ static void ipcomp4_err(struct sk_buff *skb, u32 info)
 static struct xfrm_state *ipcomp_tunnel_create(struct xfrm_state *x)
 {
         struct xfrm_state *t;
-        u8 mode = XFRM_MODE_TUNNEL;
 
         t = xfrm_state_alloc();
         if (t == NULL)
@@ -193,9 +192,7 @@ static struct xfrm_state *ipcomp_tunnel_create(struct xfrm_state *x)
         t->id.daddr.a4 = x->id.daddr.a4;
         memcpy(&t->sel, &x->sel, sizeof(t->sel));
         t->props.family = AF_INET;
-        if (x->props.mode == XFRM_MODE_BEET)
-                mode = x->props.mode;
-        t->props.mode = mode;
+        t->props.mode = x->props.mode;
         t->props.saddr.a4 = x->props.saddr.a4;
         t->props.flags = x->props.flags;
 
@@ -389,15 +386,22 @@ static int ipcomp_init_state(struct xfrm_state *x)
         if (x->encap)
                 goto out;
 
+        x->props.header_len = 0;
+        switch (x->props.mode) {
+        case XFRM_MODE_TRANSPORT:
+                break;
+        case XFRM_MODE_TUNNEL:
+                x->props.header_len += sizeof(struct iphdr);
+                break;
+        default:
+                goto out;
+        }
+
         err = -ENOMEM;
         ipcd = kzalloc(sizeof(*ipcd), GFP_KERNEL);
         if (!ipcd)
                 goto out;
 
-        x->props.header_len = 0;
-        if (x->props.mode == XFRM_MODE_TUNNEL)
-                x->props.header_len += sizeof(struct iphdr);
-
         mutex_lock(&ipcomp_resource_mutex);
         if (!ipcomp_alloc_scratches())
                 goto error;