netfilter: fix the race when initializing nf_ct_expect_hash_rnd
Since nf_ct_expect_dst_hash() may be called without nf_conntrack_lock
locked, nf_ct_expect_hash_rnd should be initialized in the atomic way.
In this patch, we use nf_conntrack_hash_rnd instead of
nf_ct_expect_hash_rnd.
Signed-off-by: Changli Gao <xiaosuo@gmail.com>
Acked-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/netfilter/nf_conntrack_core.c b/net/netfilter/nf_conntrack_core.c
index 27a5ea6..e615119 100644
--- a/net/netfilter/nf_conntrack_core.c
+++ b/net/netfilter/nf_conntrack_core.c
@@ -65,7 +65,7 @@
DEFINE_PER_CPU(struct nf_conn, nf_conntrack_untracked);
EXPORT_PER_CPU_SYMBOL(nf_conntrack_untracked);
-static unsigned int nf_conntrack_hash_rnd __read_mostly;
+unsigned int nf_conntrack_hash_rnd __read_mostly;
static u32 hash_conntrack_raw(const struct nf_conntrack_tuple *tuple, u16 zone)
{
@@ -596,6 +596,21 @@
return dropped;
}
+void init_nf_conntrack_hash_rnd(void)
+{
+ unsigned int rand;
+
+ /*
+ * Why not initialize nf_conntrack_rnd in a "init()" function ?
+ * Because there isn't enough entropy when system initializing,
+ * and we initialize it as late as possible.
+ */
+ do {
+ get_random_bytes(&rand, sizeof(rand));
+ } while (!rand);
+ cmpxchg(&nf_conntrack_hash_rnd, 0, rand);
+}
+
static struct nf_conn *
__nf_conntrack_alloc(struct net *net, u16 zone,
const struct nf_conntrack_tuple *orig,
@@ -605,18 +620,7 @@
struct nf_conn *ct;
if (unlikely(!nf_conntrack_hash_rnd)) {
- unsigned int rand;
-
- /*
- * Why not initialize nf_conntrack_rnd in a "init()" function ?
- * Because there isn't enough entropy when system initializing,
- * and we initialize it as late as possible.
- */
- do {
- get_random_bytes(&rand, sizeof(rand));
- } while (!rand);
- cmpxchg(&nf_conntrack_hash_rnd, 0, rand);
-
+ init_nf_conntrack_hash_rnd();
/* recompute the hash as nf_conntrack_hash_rnd is initialized */
hash = hash_conntrack_raw(orig, zone);
}