diff options
author | Herbert Xu <herbert@gondor.apana.org.au> | 2008-09-22 19:48:19 -0700 |
---|---|---|
committer | David S. Miller <davem@davemloft.net> | 2008-09-22 19:48:19 -0700 |
commit | 5c1824587f0797373c95719a196f6098f7c6d20c (patch) | |
tree | c3a5af01afc01d88e111c7e1821b03bf404566f6 /net/xfrm/xfrm_state.c | |
parent | fcaa40669cd798ca2ac0d15441e8a1d1145f2b16 (diff) |
ipsec: Fix xfrm_state_walk race
As discovered by Timo Teräs, the currently xfrm_state_walk scheme
is racy because if a second dump finishes before the first, we
may free xfrm states that the first dump would walk over later.
This patch fixes this by storing the dumps in a list in order
to calculate the correct completion counter which cures this
problem.
I've expanded netlink_cb in order to accomodate the extra state
related to this. It shouldn't be a big deal since netlink_cb
is kmalloced for each dump and we're just increasing it by 4 or
8 bytes.
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/xfrm/xfrm_state.c')
-rw-r--r-- | net/xfrm/xfrm_state.c | 39 |
1 files changed, 30 insertions, 9 deletions
diff --git a/net/xfrm/xfrm_state.c b/net/xfrm/xfrm_state.c index abbe2702c40..053970e8765 100644 --- a/net/xfrm/xfrm_state.c +++ b/net/xfrm/xfrm_state.c @@ -64,6 +64,9 @@ static unsigned long xfrm_state_walk_ongoing; /* Counter indicating walk completion, protected by xfrm_cfg_mutex. */ static unsigned long xfrm_state_walk_completed; +/* List of outstanding state walks used to set the completed counter. */ +static LIST_HEAD(xfrm_state_walks); + static struct xfrm_state_afinfo *xfrm_state_get_afinfo(unsigned int family); static void xfrm_state_put_afinfo(struct xfrm_state_afinfo *afinfo); @@ -1584,7 +1587,6 @@ int xfrm_state_walk(struct xfrm_state_walk *walk, if (err) { xfrm_state_hold(last); walk->state = last; - xfrm_state_walk_ongoing++; goto out; } } @@ -1599,25 +1601,44 @@ int xfrm_state_walk(struct xfrm_state_walk *walk, err = func(last, 0, data); out: spin_unlock_bh(&xfrm_state_lock); - if (old != NULL) { + if (old != NULL) xfrm_state_put(old); - xfrm_state_walk_completed++; - if (!list_empty(&xfrm_state_gc_leftovers)) - schedule_work(&xfrm_state_gc_work); - } return err; } EXPORT_SYMBOL(xfrm_state_walk); +void xfrm_state_walk_init(struct xfrm_state_walk *walk, u8 proto) +{ + walk->proto = proto; + walk->state = NULL; + walk->count = 0; + list_add_tail(&walk->list, &xfrm_state_walks); + walk->genid = ++xfrm_state_walk_ongoing; +} +EXPORT_SYMBOL(xfrm_state_walk_init); + void xfrm_state_walk_done(struct xfrm_state_walk *walk) { + struct list_head *prev; + if (walk->state != NULL) { xfrm_state_put(walk->state); walk->state = NULL; - xfrm_state_walk_completed++; - if (!list_empty(&xfrm_state_gc_leftovers)) - schedule_work(&xfrm_state_gc_work); } + + prev = walk->list.prev; + list_del(&walk->list); + + if (prev != &xfrm_state_walks) { + list_entry(prev, struct xfrm_state_walk, list)->genid = + walk->genid; + return; + } + + xfrm_state_walk_completed = walk->genid; + + if (!list_empty(&xfrm_state_gc_leftovers)) + schedule_work(&xfrm_state_gc_work); } EXPORT_SYMBOL(xfrm_state_walk_done); |