gre: fix handling of key 0
GRE driver incorrectly uses zero as a flag value. Zero is a perfectly
valid value for key, and the tunnel should match packets with no key only
with tunnels created without key, and vice versa.
This is a slightly visible change since previously it might be possible to
construct a working tunnel that sent key 0 and received only because
of the key wildcard of zero. I.e the sender sent key of zero, but tunnel
was defined without key.
Note: using gre key 0 requires iproute2 utilities v3.2 or later.
The original utility code was broken as well.
Signed-off-by: Stephen Hemminger <shemminger@vyatta.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv4/ip_gre.c b/net/ipv4/ip_gre.c
index f233c1d..0d4c383 100644
--- a/net/ipv4/ip_gre.c
+++ b/net/ipv4/ip_gre.c
@@ -214,11 +214,25 @@
return tot;
}
+/* Does key in tunnel parameters match packet */
+static bool ipgre_key_match(const struct ip_tunnel_parm *p,
+ __u32 flags, __be32 key)
+{
+ if (p->i_flags & GRE_KEY) {
+ if (flags & GRE_KEY)
+ return key == p->i_key;
+ else
+ return false; /* key expected, none present */
+ } else
+ return !(flags & GRE_KEY);
+}
+
/* Given src, dst and key, find appropriate for input tunnel. */
static struct ip_tunnel *ipgre_tunnel_lookup(struct net_device *dev,
__be32 remote, __be32 local,
- __be32 key, __be16 gre_proto)
+ __u32 flags, __be32 key,
+ __be16 gre_proto)
{
struct net *net = dev_net(dev);
int link = dev->ifindex;
@@ -233,10 +247,12 @@
for_each_ip_tunnel_rcu(ign->tunnels_r_l[h0 ^ h1]) {
if (local != t->parms.iph.saddr ||
remote != t->parms.iph.daddr ||
- key != t->parms.i_key ||
!(t->dev->flags & IFF_UP))
continue;
+ if (!ipgre_key_match(&t->parms, flags, key))
+ continue;
+
if (t->dev->type != ARPHRD_IPGRE &&
t->dev->type != dev_type)
continue;
@@ -257,10 +273,12 @@
for_each_ip_tunnel_rcu(ign->tunnels_r[h0 ^ h1]) {
if (remote != t->parms.iph.daddr ||
- key != t->parms.i_key ||
!(t->dev->flags & IFF_UP))
continue;
+ if (!ipgre_key_match(&t->parms, flags, key))
+ continue;
+
if (t->dev->type != ARPHRD_IPGRE &&
t->dev->type != dev_type)
continue;
@@ -283,10 +301,12 @@
if ((local != t->parms.iph.saddr &&
(local != t->parms.iph.daddr ||
!ipv4_is_multicast(local))) ||
- key != t->parms.i_key ||
!(t->dev->flags & IFF_UP))
continue;
+ if (!ipgre_key_match(&t->parms, flags, key))
+ continue;
+
if (t->dev->type != ARPHRD_IPGRE &&
t->dev->type != dev_type)
continue;
@@ -489,6 +509,7 @@
const int code = icmp_hdr(skb)->code;
struct ip_tunnel *t;
__be16 flags;
+ __be32 key = 0;
flags = p[0];
if (flags&(GRE_CSUM|GRE_KEY|GRE_SEQ|GRE_ROUTING|GRE_VERSION)) {
@@ -505,6 +526,9 @@
if (skb_headlen(skb) < grehlen)
return;
+ if (flags & GRE_KEY)
+ key = *(((__be32 *)p) + (grehlen / 4) - 1);
+
switch (type) {
default:
case ICMP_PARAMETERPROB:
@@ -535,9 +559,8 @@
rcu_read_lock();
t = ipgre_tunnel_lookup(skb->dev, iph->daddr, iph->saddr,
- flags & GRE_KEY ?
- *(((__be32 *)p) + (grehlen / 4) - 1) : 0,
- p[1]);
+ flags, key, p[1]);
+
if (t == NULL)
goto out;
@@ -642,9 +665,10 @@
gre_proto = *(__be16 *)(h + 2);
rcu_read_lock();
- if ((tunnel = ipgre_tunnel_lookup(skb->dev,
- iph->saddr, iph->daddr, key,
- gre_proto))) {
+ tunnel = ipgre_tunnel_lookup(skb->dev,
+ iph->saddr, iph->daddr, flags, key,
+ gre_proto);
+ if (tunnel) {
struct pcpu_tstats *tstats;
secpath_reset(skb);