netfilter: xt_recent: add address masking option

The mask option allows you put all address belonging that mask into
the same recent slot. This can be useful in case that recent is used
to detect attacks from the same network segment.

Tested for backward compatibility.

Signed-off-by: Denys Fedoryshchenko <denys@visp.net.lb>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

1 files changed, 53 insertions, 9 deletions

diff --git a/net/netfilter/xt_recent.c b/net/netfilter/xt_recent.c
index fc0d6dbe5d17..ae2ad1eec8d0 100644
--- a/net/netfilter/xt_recent.c
+++ b/net/netfilter/xt_recent.c
@@ -75,6 +75,7 @@ struct recent_entry {
 struct recent_table {
 	struct list_head	list;
 	char			name[XT_RECENT_NAME_LEN];
+	union nf_inet_addr	mask;
 	unsigned int		refcnt;
 	unsigned int		entries;
 	struct list_head	lru_list;
@@ -228,10 +229,10 @@ recent_mt(const struct sk_buff *skb, struct xt_action_param *par)
 {
 	struct net *net = dev_net(par->in ? par->in : par->out);
 	struct recent_net *recent_net = recent_pernet(net);
-	const struct xt_recent_mtinfo *info = par->matchinfo;
+	const struct xt_recent_mtinfo_v1 *info = par->matchinfo;
 	struct recent_table *t;
 	struct recent_entry *e;
-	union nf_inet_addr addr = {};
+	union nf_inet_addr addr = {}, addr_mask;
 	u_int8_t ttl;
 	bool ret = info->invert;
 
@@ -261,12 +262,15 @@ recent_mt(const struct sk_buff *skb, struct xt_action_param *par)
 
 	spin_lock_bh(&recent_lock);
 	t = recent_table_lookup(recent_net, info->name);
-	e = recent_entry_lookup(t, &addr, par->family,
+
+	nf_inet_addr_mask(&addr, &addr_mask, &t->mask);
+
+	e = recent_entry_lookup(t, &addr_mask, par->family,
 				(info->check_set & XT_RECENT_TTL) ? ttl : 0);
 	if (e == NULL) {
 		if (!(info->check_set & XT_RECENT_SET))
 			goto out;
-		e = recent_entry_init(t, &addr, par->family, ttl);
+		e = recent_entry_init(t, &addr_mask, par->family, ttl);
 		if (e == NULL)
 			par->hotdrop = true;
 		ret = !ret;
@@ -306,10 +310,10 @@ out:
 	return ret;
 }
 
-static int recent_mt_check(const struct xt_mtchk_param *par)
+static int recent_mt_check(const struct xt_mtchk_param *par,
+			   const struct xt_recent_mtinfo_v1 *info)
 {
 	struct recent_net *recent_net = recent_pernet(par->net);
-	const struct xt_recent_mtinfo *info = par->matchinfo;
 	struct recent_table *t;
 #ifdef CONFIG_PROC_FS
 	struct proc_dir_entry *pde;
@@ -361,6 +365,8 @@ static int recent_mt_check(const struct xt_mtchk_param *par)
 		goto out;
 	}
 	t->refcnt = 1;
+
+	memcpy(&t->mask, &info->mask, sizeof(t->mask));
 	strcpy(t->name, info->name);
 	INIT_LIST_HEAD(&t->lru_list);
 	for (i = 0; i < ip_list_hash_size; i++)
@@ -385,10 +391,28 @@ out:
 	return ret;
 }
 
+static int recent_mt_check_v0(const struct xt_mtchk_param *par)
+{
+	const struct xt_recent_mtinfo_v0 *info_v0 = par->matchinfo;
+	struct xt_recent_mtinfo_v1 info_v1;
+
+	/* Copy revision 0 structure to revision 1 */
+	memcpy(&info_v1, info_v0, sizeof(struct xt_recent_mtinfo));
+	/* Set default mask to ensure backward compatible behaviour */
+	memset(info_v1.mask.all, 0xFF, sizeof(info_v1.mask.all));
+
+	return recent_mt_check(par, &info_v1);
+}
+
+static int recent_mt_check_v1(const struct xt_mtchk_param *par)
+{
+	return recent_mt_check(par, par->matchinfo);
+}
+
 static void recent_mt_destroy(const struct xt_mtdtor_param *par)
 {
 	struct recent_net *recent_net = recent_pernet(par->net);
-	const struct xt_recent_mtinfo *info = par->matchinfo;
+	const struct xt_recent_mtinfo_v1 *info = par->matchinfo;
 	struct recent_table *t;
 
 	mutex_lock(&recent_mutex);
@@ -625,7 +649,7 @@ static struct xt_match recent_mt_reg[] __read_mostly = {
 		.family     = NFPROTO_IPV4,
 		.match      = recent_mt,
 		.matchsize  = sizeof(struct xt_recent_mtinfo),
-		.checkentry = recent_mt_check,
+		.checkentry = recent_mt_check_v0,
 		.destroy    = recent_mt_destroy,
 		.me         = THIS_MODULE,
 	},
@@ -635,10 +659,30 @@ static struct xt_match recent_mt_reg[] __read_mostly = {
 		.family     = NFPROTO_IPV6,
 		.match      = recent_mt,
 		.matchsize  = sizeof(struct xt_recent_mtinfo),
-		.checkentry = recent_mt_check,
+		.checkentry = recent_mt_check_v0,
+		.destroy    = recent_mt_destroy,
+		.me         = THIS_MODULE,
+	},
+	{
+		.name       = "recent",
+		.revision   = 1,
+		.family     = NFPROTO_IPV4,
+		.match      = recent_mt,
+		.matchsize  = sizeof(struct xt_recent_mtinfo_v1),
+		.checkentry = recent_mt_check_v1,
 		.destroy    = recent_mt_destroy,
 		.me         = THIS_MODULE,
 	},
+	{
+		.name       = "recent",
+		.revision   = 1,
+		.family     = NFPROTO_IPV6,
+		.match      = recent_mt,
+		.matchsize  = sizeof(struct xt_recent_mtinfo_v1),
+		.checkentry = recent_mt_check_v1,
+		.destroy    = recent_mt_destroy,
+		.me         = THIS_MODULE,
+	}
 };
 
 static int __init recent_mt_init(void)