Revert "netfilter: xt_recent: relax ip_pkt_list_tot restrictions"

This reverts commit abc86d0f as it is
broken in 3.19 and is easier to revert here than try to fix it.

Reported-by: Florian Westphal <fw@strlen.de
Reported-by: David Miller <davem@redhat.com>
Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org

net/netfilter/xt_recent.c

@@ -43,29 +43,25 @@ MODULE_LICENSE("GPL");
 MODULE_ALIAS("ipt_recent");
 MODULE_ALIAS("ip6t_recent");
 
-static unsigned int ip_list_tot __read_mostly = 100;
-static unsigned int ip_list_hash_size __read_mostly;
-static unsigned int ip_list_perms __read_mostly = 0644;
-static unsigned int ip_list_uid __read_mostly;
-static unsigned int ip_list_gid __read_mostly;
+static unsigned int ip_list_tot = 100;
+static unsigned int ip_pkt_list_tot = 20;
+static unsigned int ip_list_hash_size = 0;
+static unsigned int ip_list_perms = 0644;
+static unsigned int ip_list_uid = 0;
+static unsigned int ip_list_gid = 0;
 module_param(ip_list_tot, uint, 0400);
+module_param(ip_pkt_list_tot, uint, 0400);
 module_param(ip_list_hash_size, uint, 0400);
 module_param(ip_list_perms, uint, 0400);
 module_param(ip_list_uid, uint, S_IRUGO | S_IWUSR);
 module_param(ip_list_gid, uint, S_IRUGO | S_IWUSR);
 MODULE_PARM_DESC(ip_list_tot, "number of IPs to remember per list");
+MODULE_PARM_DESC(ip_pkt_list_tot, "number of packets per IP address to remember (max. 255)");
 MODULE_PARM_DESC(ip_list_hash_size, "size of hash table used to look up IPs");
 MODULE_PARM_DESC(ip_list_perms, "permissions on /proc/net/xt_recent/* files");
 MODULE_PARM_DESC(ip_list_uid, "default owner of /proc/net/xt_recent/* files");
 MODULE_PARM_DESC(ip_list_gid, "default owning group of /proc/net/xt_recent/* files");
 
-/* retained for backwards compatibility */
-static unsigned int ip_pkt_list_tot __read_mostly;
-module_param(ip_pkt_list_tot, uint, 0400);
-MODULE_PARM_DESC(ip_pkt_list_tot, "number of packets per IP address to remember (max. 255)");
-
-#define XT_RECENT_MAX_NSTAMPS	256
-
 struct recent_entry {
 	struct list_head	list;
 	struct list_head	lru_list;
@@ -83,7 +79,6 @@ struct recent_table {
 	union nf_inet_addr	mask;
 	unsigned int		refcnt;
 	unsigned int		entries;
-	u8			nstamps_max_mask;
 	struct list_head	lru_list;
 	struct list_head	iphash[0];
 };
@@ -95,8 +90,7 @@ struct recent_net {
 #endif
 };
 
-static int recent_net_id __read_mostly;
-
+static int recent_net_id;
 static inline struct recent_net *recent_pernet(struct net *net)
 {
 	return net_generic(net, recent_net_id);
@@ -177,15 +171,12 @@ recent_entry_init(struct recent_table *t, const union nf_inet_addr *addr,
 		  u_int16_t family, u_int8_t ttl)
 {
 	struct recent_entry *e;
-	unsigned int nstamps_max = t->nstamps_max_mask;
 
 	if (t->entries >= ip_list_tot) {
 		e = list_entry(t->lru_list.next, struct recent_entry, lru_list);
 		recent_entry_remove(t, e);
 	}
-
-	nstamps_max += 1;
-	e = kmalloc(sizeof(*e) + sizeof(e->stamps[0]) * nstamps_max,
+	e = kmalloc(sizeof(*e) + sizeof(e->stamps[0]) * ip_pkt_list_tot,
 		    GFP_ATOMIC);
 	if (e == NULL)
 		return NULL;
@@ -206,7 +197,7 @@ recent_entry_init(struct recent_table *t, const union nf_inet_addr *addr,
 
 static void recent_entry_update(struct recent_table *t, struct recent_entry *e)
 {
-	e->index &= t->nstamps_max_mask;
+	e->index %= ip_pkt_list_tot;
 	e->stamps[e->index++] = jiffies;
 	if (e->index > e->nstamps)
 		e->nstamps = e->index;
@@ -335,7 +326,6 @@ static int recent_mt_check(const struct xt_mtchk_param *par,
 	kuid_t uid;
 	kgid_t gid;
 #endif
-	unsigned int nstamp_mask;
 	unsigned int i;
 	int ret = -EINVAL;
 	size_t sz;
@@ -359,33 +349,19 @@ static int recent_mt_check(const struct xt_mtchk_param *par,
 		return -EINVAL;
 	if ((info->check_set & XT_RECENT_REAP) && !info->seconds)
 		return -EINVAL;
-	if (info->hit_count >= XT_RECENT_MAX_NSTAMPS) {
-		pr_info("hitcount (%u) is larger than allowed maximum (%u)\n",
-			info->hit_count, XT_RECENT_MAX_NSTAMPS - 1);
+	if (info->hit_count > ip_pkt_list_tot) {
+		pr_info("hitcount (%u) is larger than "
+			"packets to be remembered (%u)\n",
+			info->hit_count, ip_pkt_list_tot);
 		return -EINVAL;
 	}
 	if (info->name[0] == '\0' ||
 	    strnlen(info->name, XT_RECENT_NAME_LEN) == XT_RECENT_NAME_LEN)
 		return -EINVAL;
 
-	if (ip_pkt_list_tot && info->hit_count < ip_pkt_list_tot)
-		nstamp_mask = roundup_pow_of_two(ip_pkt_list_tot) - 1;
-	else if (info->hit_count)
-		nstamp_mask = roundup_pow_of_two(info->hit_count) - 1;
-	else
-		nstamp_mask = 32 - 1;
-
 	mutex_lock(&recent_mutex);
 	t = recent_table_lookup(recent_net, info->name);
 	if (t != NULL) {
-		if (info->hit_count > t->nstamps_max_mask) {
-			pr_info("hitcount (%u) is larger than packets to be remembered (%u) for table %s\n",
-				info->hit_count, t->nstamps_max_mask + 1,
-				info->name);
-			ret = -EINVAL;
-			goto out;
-		}
-
 		t->refcnt++;
 		ret = 0;
 		goto out;
@@ -401,7 +377,6 @@ static int recent_mt_check(const struct xt_mtchk_param *par,
 		goto out;
 	}
 	t->refcnt = 1;
-	t->nstamps_max_mask = nstamp_mask;
 
 	memcpy(&t->mask, &info->mask, sizeof(t->mask));
 	strcpy(t->name, info->name);
@@ -522,12 +497,9 @@ static void recent_seq_stop(struct seq_file *s, void *v)
 static int recent_seq_show(struct seq_file *seq, void *v)
 {
 	const struct recent_entry *e = v;
-	struct recent_iter_state *st = seq->private;
-	const struct recent_table *t = st->table;
 	unsigned int i;
 
-	i = (e->index - 1) & t->nstamps_max_mask;
-
+	i = (e->index - 1) % ip_pkt_list_tot;
 	if (e->family == NFPROTO_IPV4)
 		seq_printf(seq, "src=%pI4 ttl: %u last_seen: %lu oldest_pkt: %u",
 			   &e->addr.ip, e->ttl, e->stamps[i], e->index);
@@ -745,9 +717,7 @@ static int __init recent_mt_init(void)
 {
 	int err;
 
-	BUILD_BUG_ON_NOT_POWER_OF_2(XT_RECENT_MAX_NSTAMPS);
-
-	if (!ip_list_tot || ip_pkt_list_tot >= XT_RECENT_MAX_NSTAMPS)
+	if (!ip_list_tot || !ip_pkt_list_tot || ip_pkt_list_tot > 255)
 		return -EINVAL;
 	ip_list_hash_size = 1 << fls(ip_list_tot);