[ICMP]: Ensure that ICMP relookup maintains status quo

The ICMP relookup path is only meant to modify behaviour when
appropriate IPsec policies are in place and marked as requiring
relookups.  It is certainly not meant to modify behaviour when
IPsec policies don't exist at all.

However, due to an oversight on the error paths existing behaviour
may in fact change should one of the relookup steps fail.

This patch corrects this by redirecting all errors on relookup
failures to the previous code path.  That is, if the initial
xfrm_lookup let the packet pass, we will stand by that decision
should the relookup fail due to an error.

This should be safe from a security point-of-view because compliant
systems must install a default deny policy so the packet would'nt
have passed in that case.

Many thanks to Julian Anastasov for pointing out this error.

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

diff --git a/net/ipv4/icmp.c b/net/ipv4/icmp.c
index a944e8053e28ff84f4989bcaa0ec2395cd348ac4..40508babad8c5366764bfc0c79ff568b37be14b1 100644 (file)
--- a/net/ipv4/icmp.c
+++ b/net/ipv4/icmp.c
@@ -591,7 +591,7 @@ void icmp_send(struct sk_buff *skb_in, int type, int code, __be32 info)
                }
 
                if (xfrm_decode_session_reverse(skb_in, &fl, AF_INET))
-                       goto ende;
+                       goto relookup_failed;
 
                if (inet_addr_type(net, fl.fl4_src) == RTN_LOCAL)
                        err = __ip_route_output_key(net, &rt2, &fl);
@@ -601,7 +601,7 @@ void icmp_send(struct sk_buff *skb_in, int type, int code, __be32 info)
 
                        fl2.fl4_dst = fl.fl4_src;
                        if (ip_route_output_key(net, &rt2, &fl2))
-                               goto ende;
+                               goto relookup_failed;
 
                        /* Ugh! */
                        odst = skb_in->dst;
@@ -614,21 +614,23 @@ void icmp_send(struct sk_buff *skb_in, int type, int code, __be32 info)
                }
 
                if (err)
-                       goto ende;
+                       goto relookup_failed;
 
                err = xfrm_lookup((struct dst_entry **)&rt2, &fl, NULL,
                                  XFRM_LOOKUP_ICMP);
-               if (err == -ENOENT) {
+               switch (err) {
+               case 0:
+                       dst_release(&rt->u.dst);
+                       rt = rt2;
+                       break;
+               case -EPERM:
+                       goto ende;
+               default:
+relookup_failed:
                        if (!rt)
                                goto out_unlock;
-                       goto route_done;
+                       break;
                }
-
-               dst_release(&rt->u.dst);
-               rt = rt2;
-
-               if (err)
-                       goto out_unlock;
        }
 
 route_done:

diff --git a/net/ipv6/icmp.c b/net/ipv6/icmp.c
index f204a7275a0d0e1e740d64f713d7d3d28cda9b78..893287ecc6289e2bf76ba5af2f9bc1efb74e0799 100644 (file)
--- a/net/ipv6/icmp.c
+++ b/net/ipv6/icmp.c
@@ -436,24 +436,26 @@ void icmpv6_send(struct sk_buff *skb, int type, int code, __u32 info,
        }
 
        if (xfrm_decode_session_reverse(skb, &fl2, AF_INET6))
-               goto out_dst_release;
+               goto relookup_failed;
 
        if (ip6_dst_lookup(sk, &dst2, &fl))
-               goto out_dst_release;
+               goto relookup_failed;
 
        err = xfrm_lookup(&dst2, &fl, sk, XFRM_LOOKUP_ICMP);
-       if (err == -ENOENT) {
+       switch (err) {
+       case 0:
+               dst_release(dst);
+               dst = dst2;
+               break;
+       case -EPERM:
+               goto out_dst_release;
+       default:
+relookup_failed:
                if (!dst)
                        goto out;
-               goto route_done;
+               break;
        }
 
-       dst_release(dst);
-       dst = dst2;
-
-       if (err)
-               goto out;
-
 route_done:
        if (ipv6_addr_is_multicast(&fl.fl6_dst))
                hlimit = np->mcast_hops;