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authorPavel Emelyanov <xemul@openvz.org>2008-03-24 14:48:59 -0700
committerDavid S. Miller <davem@davemloft.net>2008-03-24 14:48:59 -0700
commitfa86d322d89995fef1bfb5cc768b89d8c22ea0d9 (patch)
treee657b8adc9ccd2e13b2e2276fab4733a273ded09 /include
parent8f3ea33a5078a09eba12bfe57424507809367756 (diff)
[NEIGH]: Fix race between pneigh deletion and ipv6's ndisc_recv_ns (v3).
Proxy neighbors do not have any reference counting, so any caller of pneigh_lookup (unless it's a netlink triggered add/del routine) should _not_ perform any actions on the found proxy entry. There's one exception from this rule - the ipv6's ndisc_recv_ns() uses found entry to check the flags for NTF_ROUTER. This creates a race between the ndisc and pneigh_delete - after the pneigh is returned to the caller, the nd_tbl.lock is dropped and the deleting procedure may proceed. One of the fixes would be to add a reference counting, but this problem exists for ndisc only. Besides such a patch would be too big for -rc4. So I propose to introduce a __pneigh_lookup() which is supposed to be called with the lock held and use it in ndisc code to check the flags on alive pneigh entry. Changes from v2: As David noticed, Exported the __pneigh_lookup() to ipv6 module. The checkpatch generates a warning on it, since the EXPORT_SYMBOL does not follow the symbol itself, but in this file all the exports come at the end, so I decided no to break this harmony. Changes from v1: Fixed comments from YOSHIFUJI - indentation of prototype in header and the pndisc_check_router() name - and a compilation fix, pointed by Daniel - the is_routed was (falsely) considered as uninitialized by gcc. Signed-off-by: Pavel Emelyanov <xemul@openvz.org> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'include')
-rw-r--r--include/net/neighbour.h4
1 files changed, 4 insertions, 0 deletions
diff --git a/include/net/neighbour.h b/include/net/neighbour.h
index ebbfb509822e..64a5f0120b52 100644
--- a/include/net/neighbour.h
+++ b/include/net/neighbour.h
@@ -218,6 +218,10 @@ extern unsigned long neigh_rand_reach_time(unsigned long base);
extern void pneigh_enqueue(struct neigh_table *tbl, struct neigh_parms *p,
struct sk_buff *skb);
extern struct pneigh_entry *pneigh_lookup(struct neigh_table *tbl, struct net *net, const void *key, struct net_device *dev, int creat);
+extern struct pneigh_entry *__pneigh_lookup(struct neigh_table *tbl,
+ struct net *net,
+ const void *key,
+ struct net_device *dev);
extern int pneigh_delete(struct neigh_table *tbl, struct net *net, const void *key, struct net_device *dev);
extern void neigh_app_ns(struct neighbour *n);

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