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authorVishwanath Pai <vpai@akamai.com>2016-03-16 21:49:00 +0100
committerPablo Neira Ayuso <pablo@netfilter.org>2016-03-28 17:57:45 +0200
commit596cf3fe5854fe2b1703b0466ed6bf9cfb83c91e (patch)
treefe02169500b0046f42b7f85e91c92b3cfb4fa342 /net
parentd7be81a5916bdb1d904803958e5991a16f7ae4b2 (diff)
downloadlinux-596cf3fe5854fe2b1703b0466ed6bf9cfb83c91e.tar.bz2
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 'net')
-rw-r--r--net/netfilter/ipset/ip_set_bitmap_gen.h2
-rw-r--r--net/netfilter/ipset/ip_set_core.c33
-rw-r--r--net/netfilter/ipset/ip_set_hash_gen.h2
-rw-r--r--net/netfilter/ipset/ip_set_list_set.c2
4 files changed, 31 insertions, 8 deletions
diff --git a/net/netfilter/ipset/ip_set_bitmap_gen.h b/net/netfilter/ipset/ip_set_bitmap_gen.h
index b0bc475f641e..2e8e7e5fb4a6 100644
--- a/net/netfilter/ipset/ip_set_bitmap_gen.h
+++ b/net/netfilter/ipset/ip_set_bitmap_gen.h
@@ -95,7 +95,7 @@ mtype_head(struct ip_set *set, struct sk_buff *skb)
if (!nested)
goto nla_put_failure;
if (mtype_do_head(skb, map) ||
- nla_put_net32(skb, IPSET_ATTR_REFERENCES, htonl(set->ref - 1)) ||
+ nla_put_net32(skb, IPSET_ATTR_REFERENCES, htonl(set->ref)) ||
nla_put_net32(skb, IPSET_ATTR_MEMSIZE, htonl(memsize)))
goto nla_put_failure;
if (unlikely(ip_set_put_flags(skb, set)))
diff --git a/net/netfilter/ipset/ip_set_core.c b/net/netfilter/ipset/ip_set_core.c
index 7e6568cad494..a748b0c2c981 100644
--- a/net/netfilter/ipset/ip_set_core.c
+++ b/net/netfilter/ipset/ip_set_core.c
@@ -497,6 +497,26 @@ __ip_set_put(struct ip_set *set)
write_unlock_bh(&ip_set_ref_lock);
}
+/* set->ref can be swapped out by ip_set_swap, netlink events (like dump) need
+ * a separate reference counter
+ */
+static inline void
+__ip_set_get_netlink(struct ip_set *set)
+{
+ write_lock_bh(&ip_set_ref_lock);
+ set->ref_netlink++;
+ write_unlock_bh(&ip_set_ref_lock);
+}
+
+static inline void
+__ip_set_put_netlink(struct ip_set *set)
+{
+ write_lock_bh(&ip_set_ref_lock);
+ BUG_ON(set->ref_netlink == 0);
+ set->ref_netlink--;
+ write_unlock_bh(&ip_set_ref_lock);
+}
+
/* Add, del and test set entries from kernel.
*
* The set behind the index must exist and must be referenced
@@ -1002,7 +1022,7 @@ static int ip_set_destroy(struct net *net, struct sock *ctnl,
if (!attr[IPSET_ATTR_SETNAME]) {
for (i = 0; i < inst->ip_set_max; i++) {
s = ip_set(inst, i);
- if (s && s->ref) {
+ if (s && (s->ref || s->ref_netlink)) {
ret = -IPSET_ERR_BUSY;
goto out;
}
@@ -1024,7 +1044,7 @@ static int ip_set_destroy(struct net *net, struct sock *ctnl,
if (!s) {
ret = -ENOENT;
goto out;
- } else if (s->ref) {
+ } else if (s->ref || s->ref_netlink) {
ret = -IPSET_ERR_BUSY;
goto out;
}
@@ -1171,6 +1191,9 @@ static int ip_set_swap(struct net *net, struct sock *ctnl, struct sk_buff *skb,
from->family == to->family))
return -IPSET_ERR_TYPE_MISMATCH;
+ if (from->ref_netlink || to->ref_netlink)
+ return -EBUSY;
+
strncpy(from_name, from->name, IPSET_MAXNAMELEN);
strncpy(from->name, to->name, IPSET_MAXNAMELEN);
strncpy(to->name, from_name, IPSET_MAXNAMELEN);
@@ -1206,7 +1229,7 @@ ip_set_dump_done(struct netlink_callback *cb)
if (set->variant->uref)
set->variant->uref(set, cb, false);
pr_debug("release set %s\n", set->name);
- __ip_set_put_byindex(inst, index);
+ __ip_set_put_netlink(set);
}
return 0;
}
@@ -1328,7 +1351,7 @@ dump_last:
if (!cb->args[IPSET_CB_ARG0]) {
/* Start listing: make sure set won't be destroyed */
pr_debug("reference set\n");
- set->ref++;
+ set->ref_netlink++;
}
write_unlock_bh(&ip_set_ref_lock);
nlh = start_msg(skb, NETLINK_CB(cb->skb).portid,
@@ -1396,7 +1419,7 @@ release_refcount:
if (set->variant->uref)
set->variant->uref(set, cb, false);
pr_debug("release set %s\n", set->name);
- __ip_set_put_byindex(inst, index);
+ __ip_set_put_netlink(set);
cb->args[IPSET_CB_ARG0] = 0;
}
out:
diff --git a/net/netfilter/ipset/ip_set_hash_gen.h b/net/netfilter/ipset/ip_set_hash_gen.h
index e5336ab36d67..d32fd6b036bf 100644
--- a/net/netfilter/ipset/ip_set_hash_gen.h
+++ b/net/netfilter/ipset/ip_set_hash_gen.h
@@ -1082,7 +1082,7 @@ 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)))
goto nla_put_failure;
if (unlikely(ip_set_put_flags(skb, set)))
diff --git a/net/netfilter/ipset/ip_set_list_set.c b/net/netfilter/ipset/ip_set_list_set.c
index 24c6c1962aea..a2a89e4e0a14 100644
--- a/net/netfilter/ipset/ip_set_list_set.c
+++ b/net/netfilter/ipset/ip_set_list_set.c
@@ -458,7 +458,7 @@ list_set_head(struct ip_set *set, struct sk_buff *skb)
if (!nested)
goto nla_put_failure;
if (nla_put_net32(skb, IPSET_ATTR_SIZE, htonl(map->size)) ||
- nla_put_net32(skb, IPSET_ATTR_REFERENCES, htonl(set->ref - 1)) ||
+ nla_put_net32(skb, IPSET_ATTR_REFERENCES, htonl(set->ref)) ||
nla_put_net32(skb, IPSET_ATTR_MEMSIZE,
htonl(sizeof(*map) + n * set->dsize)))
goto nla_put_failure;