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author | Vishwanath Pai <vpai@akamai.com> | 2016-03-16 21:49:00 +0100 |
---|---|---|
committer | Pablo Neira Ayuso <pablo@netfilter.org> | 2016-03-28 17:57:45 +0200 |
commit | 596cf3fe5854fe2b1703b0466ed6bf9cfb83c91e (patch) | |
tree | fe02169500b0046f42b7f85e91c92b3cfb4fa342 /include | |
parent | d7be81a5916bdb1d904803958e5991a16f7ae4b2 (diff) | |
download | linux-596cf3fe5854fe2b1703b0466ed6bf9cfb83c91e.tar.gz linux-596cf3fe5854fe2b1703b0466ed6bf9cfb83c91e.tar.bz2 linux-596cf3fe5854fe2b1703b0466ed6bf9cfb83c91e.zip |
netfilter: ipset: fix race condition in ipset save, swap and delete
This fix adds a new reference counter (ref_netlink) for the struct ip_set.
The other reference counter (ref) can be swapped out by ip_set_swap and we
need a separate counter to keep track of references for netlink events
like dump. Using the same ref counter for dump causes a race condition
which can be demonstrated by the following script:
ipset create hash_ip1 hash:ip family inet hashsize 1024 maxelem 500000 \
counters
ipset create hash_ip2 hash:ip family inet hashsize 300000 maxelem 500000 \
counters
ipset create hash_ip3 hash:ip family inet hashsize 1024 maxelem 500000 \
counters
ipset save &
ipset swap hash_ip3 hash_ip2
ipset destroy hash_ip3 /* will crash the machine */
Swap will exchange the values of ref so destroy will see ref = 0 instead of
ref = 1. With this fix in place swap will not succeed because ipset save
still has ref_netlink on the set (ip_set_swap doesn't swap ref_netlink).
Both delete and swap will error out if ref_netlink != 0 on the set.
Note: The changes to *_head functions is because previously we would
increment ref whenever we called these functions, we don't do that
anymore.
Reviewed-by: Joshua Hunt <johunt@akamai.com>
Signed-off-by: Vishwanath Pai <vpai@akamai.com>
Signed-off-by: Jozsef Kadlecsik <kadlec@blackhole.kfki.hu>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Diffstat (limited to 'include')
-rw-r--r-- | include/linux/netfilter/ipset/ip_set.h | 4 |
1 files changed, 4 insertions, 0 deletions
diff --git a/include/linux/netfilter/ipset/ip_set.h b/include/linux/netfilter/ipset/ip_set.h index 0e1f433cc4b7..f48b8a664b0f 100644 --- a/include/linux/netfilter/ipset/ip_set.h +++ b/include/linux/netfilter/ipset/ip_set.h @@ -234,6 +234,10 @@ struct ip_set { spinlock_t lock; /* References to the set */ u32 ref; + /* References to the set for netlink events like dump, + * ref can be swapped out by ip_set_swap + */ + u32 ref_netlink; /* The core set type */ struct ip_set_type *type; /* The type variant doing the real job */ |