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| author | Pavel Emelyanov <xemul@openvz.org> | 2008-03-24 14:48:59 -0700 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2008-03-24 14:48:59 -0700 |
| commit | fa86d322d89995fef1bfb5cc768b89d8c22ea0d9 (patch) | |
| tree | e657b8adc9ccd2e13b2e2276fab4733a273ded09 /include | |
| parent | 8f3ea33a5078a09eba12bfe57424507809367756 (diff) | |
| download | linux-fa86d322d89995fef1bfb5cc768b89d8c22ea0d9.tar.bz2 | |
[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.h | 4 |
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); |