netfilter: xtables: do not grab random bytes at __init

"It is deliberately not done in the init function, since we might not
have sufficient random while booting."
Signed-off-by: Jan Engelhardt <jengelh@medozas.de>
Signed-off-by: Patrick McHardy <kaber@trash.net>

net/netfilter/xt_NFQUEUE.c

@@ -28,6 +28,7 @@ MODULE_ALIAS("ip6t_NFQUEUE");
 MODULE_ALIAS("arpt_NFQUEUE");
 
 static u32 jhash_initval __read_mostly;
+static bool rnd_inited __read_mostly;
 
 static unsigned int
 nfqueue_tg(struct sk_buff *skb, const struct xt_target_param *par)
@@ -90,6 +91,10 @@ static bool nfqueue_tg_v1_check(const struct xt_tgchk_param *par)
 	const struct xt_NFQ_info_v1 *info = par->targinfo;
 	u32 maxid;
 
+	if (unlikely(!rnd_inited)) {
+		get_random_bytes(&jhash_initval, sizeof(jhash_initval));
+		rnd_inited = true;
+	}
 	if (info->queues_total == 0) {
 		pr_err("NFQUEUE: number of total queues is 0\n");
 		return false;
@@ -135,7 +140,6 @@ static struct xt_target nfqueue_tg_reg[] __read_mostly = {
 
 static int __init nfqueue_tg_init(void)
 {
-	get_random_bytes(&jhash_initval, sizeof(jhash_initval));
 	return xt_register_targets(nfqueue_tg_reg, ARRAY_SIZE(nfqueue_tg_reg));
 }
 

net/netfilter/xt_RATEEST.c

@@ -23,6 +23,7 @@ static DEFINE_MUTEX(xt_rateest_mutex);
 #define RATEEST_HSIZE	16
 static struct hlist_head rateest_hash[RATEEST_HSIZE] __read_mostly;
 static unsigned int jhash_rnd __read_mostly;
+static bool rnd_inited __read_mostly;
 
 static unsigned int xt_rateest_hash(const char *name)
 {
@@ -93,6 +94,11 @@ static bool xt_rateest_tg_checkentry(const struct xt_tgchk_param *par)
 		struct gnet_estimator	est;
 	} cfg;
 
+	if (unlikely(!rnd_inited)) {
+		get_random_bytes(&jhash_rnd, sizeof(jhash_rnd));
+		rnd_inited = true;
+	}
+
 	est = xt_rateest_lookup(info->name);
 	if (est) {
 		/*
@@ -164,7 +170,6 @@ static int __init xt_rateest_tg_init(void)
 	for (i = 0; i < ARRAY_SIZE(rateest_hash); i++)
 		INIT_HLIST_HEAD(&rateest_hash[i]);
 
-	get_random_bytes(&jhash_rnd, sizeof(jhash_rnd));
 	return xt_register_target(&xt_rateest_tg_reg);
 }