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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>
This commit is contained in:
stephen hemminger 2012-09-24 18:12:23 +00:00 committed by David S. Miller
parent aa99521eed
commit d208328765
1 changed files with 34 additions and 10 deletions
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44
net/ipv4/ip_gre.c
View File

@ -214,11 +214,25 @@ static struct rtnl_link_stats64 *ipgre_get_stats64(struct net_device *dev,
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 @@ static struct ip_tunnel *ipgre_tunnel_lookup(struct net_device *dev,
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 @@ static struct ip_tunnel *ipgre_tunnel_lookup(struct net_device *dev,
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 @@ static struct ip_tunnel *ipgre_tunnel_lookup(struct net_device *dev,
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 @@ static void ipgre_err(struct sk_buff *skb, u32 info)
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 @@ static void ipgre_err(struct sk_buff *skb, u32 info)
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 @@ static void ipgre_err(struct sk_buff *skb, u32 info)
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 @@ static int ipgre_rcv(struct sk_buff *skb)
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);