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author | Vishwanath Pai <vpai@akamai.com> | 2016-03-16 09:03:30 +0100 |
---|---|---|
committer | Jozsef Kadlecsik <kadlec@blackhole.kfki.hu> | 2016-03-16 09:03:30 +0100 |
commit | 4c70c227fdbb4ec302286bb7ade2ec4051b4d508 (patch) | |
tree | f31c5063691ff6f519cea879c964dbf641975058 /kernel/net/netfilter/ipset/ip_set_hash_gen.h | |
parent | e2b58fe3c45933957ec38161fc255a0f88333d14 (diff) | |
download | ipset-4c70c227fdbb4ec302286bb7ade2ec4051b4d508.tar.gz |
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>
Diffstat (limited to 'kernel/net/netfilter/ipset/ip_set_hash_gen.h')
-rw-r--r-- | kernel/net/netfilter/ipset/ip_set_hash_gen.h | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/kernel/net/netfilter/ipset/ip_set_hash_gen.h b/kernel/net/netfilter/ipset/ip_set_hash_gen.h index 75c6d22..9128a22 100644 --- a/kernel/net/netfilter/ipset/ip_set_hash_gen.h +++ b/kernel/net/netfilter/ipset/ip_set_hash_gen.h @@ -1075,7 +1075,7 @@ mtype_head(struct ip_set *set, struct sk_buff *skb) if (nla_put_u32(skb, IPSET_ATTR_MARKMASK, h->markmask)) goto nla_put_failure; #endif - if (nla_put_net32(skb, IPSET_ATTR_REFERENCES, htonl(set->ref - 1)) || + if (nla_put_net32(skb, IPSET_ATTR_REFERENCES, htonl(set->ref)) || nla_put_net32(skb, IPSET_ATTR_MEMSIZE, htonl(memsize)) || nla_put_net32(skb, IPSET_ATTR_ELEMENTS, htonl(set->elements))) goto nla_put_failure; |