[INET]: Small possible memory leak in FIB rules

This patch fixes a small memory leak. Default fib rules can be deleted by
the user if the rule does not carry FIB_RULE_PERMANENT flag, f.e. by
	ip rule flush

Such a rule will not be freed as the ref-counter has 2 on start and becomes
clearly unreachable after removal.

Signed-off-by: Denis V. Lunev <den@openvz.org>
Acked-by: Alexey Kuznetsov <kuznet@ms2.inr.ac.ru>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/net/fib_rules.h

@@ -107,4 +107,7 @@ extern int			fib_rules_unregister(struct fib_rules_ops *);
 extern int			fib_rules_lookup(struct fib_rules_ops *,
 						 struct flowi *, int flags,
 						 struct fib_lookup_arg *);
+extern int			fib_default_rule_add(struct fib_rules_ops *,
+						     u32 pref, u32 table,
+						     u32 flags);
 #endif

net/core/fib_rules.c

@@ -18,6 +18,28 @@
 static LIST_HEAD(rules_ops);
 static DEFINE_SPINLOCK(rules_mod_lock);
 
+int fib_default_rule_add(struct fib_rules_ops *ops,
+			 u32 pref, u32 table, u32 flags)
+{
+	struct fib_rule *r;
+
+	r = kzalloc(ops->rule_size, GFP_KERNEL);
+	if (r == NULL)
+		return -ENOMEM;
+
+	atomic_set(&r->refcnt, 1);
+	r->action = FR_ACT_TO_TBL;
+	r->pref = pref;
+	r->table = table;
+	r->flags = flags;
+
+	/* The lock is not required here, the list in unreacheable
+	 * at the moment this function is called */
+	list_add_tail(&r->list, &ops->rules_list);
+	return 0;
+}
+EXPORT_SYMBOL(fib_default_rule_add);
+
 static void notify_rule_change(int event, struct fib_rule *rule,
 			       struct fib_rules_ops *ops, struct nlmsghdr *nlh,
 			       u32 pid);

net/decnet/dn_rules.c

@@ -48,15 +48,6 @@ struct dn_fib_rule
 	u8			flags;
 };
 
-static struct dn_fib_rule default_rule = {
-	.common = {
-		.refcnt =		ATOMIC_INIT(2),
-		.pref =			0x7fff,
-		.table =		RT_TABLE_MAIN,
-		.action =		FR_ACT_TO_TBL,
-	},
-};
-
 
 int dn_fib_lookup(struct flowi *flp, struct dn_fib_res *res)
 {
@@ -262,8 +253,8 @@ static struct fib_rules_ops dn_fib_rules_ops = {
 
 void __init dn_fib_rules_init(void)
 {
-	list_add_tail(&default_rule.common.list,
-			&dn_fib_rules_ops.rules_list);
+	BUG_ON(fib_default_rule_add(&dn_fib_rules_ops, 0x7fff,
+			            RT_TABLE_MAIN, 0));
 	fib_rules_register(&dn_fib_rules_ops);
 }
 

net/ipv4/fib_rules.c

@@ -49,33 +49,6 @@ struct fib4_rule
 #endif
 };
 
-static struct fib4_rule default_rule = {
-	.common = {
-		.refcnt =	ATOMIC_INIT(2),
-		.pref =		0x7FFF,
-		.table =	RT_TABLE_DEFAULT,
-		.action =	FR_ACT_TO_TBL,
-	},
-};
-
-static struct fib4_rule main_rule = {
-	.common = {
-		.refcnt =	ATOMIC_INIT(2),
-		.pref =		0x7FFE,
-		.table =	RT_TABLE_MAIN,
-		.action =	FR_ACT_TO_TBL,
-	},
-};
-
-static struct fib4_rule local_rule = {
-	.common = {
-		.refcnt =	ATOMIC_INIT(2),
-		.table =	RT_TABLE_LOCAL,
-		.action =	FR_ACT_TO_TBL,
-		.flags =	FIB_RULE_PERMANENT,
-	},
-};
-
 #ifdef CONFIG_NET_CLS_ROUTE
 u32 fib_rules_tclass(struct fib_result *res)
 {
@@ -319,11 +292,27 @@ static struct fib_rules_ops fib4_rules_ops = {
 	.owner		= THIS_MODULE,
 };
 
-void __init fib4_rules_init(void)
+static int __init fib_default_rules_init(void)
 {
-	list_add_tail(&local_rule.common.list, &fib4_rules_ops.rules_list);
-	list_add_tail(&main_rule.common.list, &fib4_rules_ops.rules_list);
-	list_add_tail(&default_rule.common.list, &fib4_rules_ops.rules_list);
+	int err;
+
+	err = fib_default_rule_add(&fib4_rules_ops, 0,
+				   RT_TABLE_LOCAL, FIB_RULE_PERMANENT);
+	if (err < 0)
+		return err;
+	err = fib_default_rule_add(&fib4_rules_ops, 0x7FFE,
+				   RT_TABLE_MAIN, 0);
+	if (err < 0)
+		return err;
+	err = fib_default_rule_add(&fib4_rules_ops, 0x7FFF,
+				   RT_TABLE_DEFAULT, 0);
+	if (err < 0)
+		return err;
+	return 0;
+}
 
+void __init fib4_rules_init(void)
+{
+	BUG_ON(fib_default_rules_init());
 	fib_rules_register(&fib4_rules_ops);
 }

net/ipv6/fib6_rules.c

@@ -31,25 +31,6 @@ struct fib6_rule
 
 static struct fib_rules_ops fib6_rules_ops;
 
-static struct fib6_rule main_rule = {
-	.common = {
-		.refcnt =	ATOMIC_INIT(2),
-		.pref =		0x7FFE,
-		.action =	FR_ACT_TO_TBL,
-		.table =	RT6_TABLE_MAIN,
-	},
-};
-
-static struct fib6_rule local_rule = {
-	.common = {
-		.refcnt =	ATOMIC_INIT(2),
-		.pref =		0,
-		.action =	FR_ACT_TO_TBL,
-		.table =	RT6_TABLE_LOCAL,
-		.flags =	FIB_RULE_PERMANENT,
-	},
-};
-
 struct dst_entry *fib6_rule_lookup(struct flowi *fl, int flags,
 				   pol_lookup_t lookup)
 {
@@ -270,11 +251,23 @@ static struct fib_rules_ops fib6_rules_ops = {
 	.owner			= THIS_MODULE,
 };
 
-void __init fib6_rules_init(void)
+static int __init fib6_default_rules_init(void)
 {
-	list_add_tail(&local_rule.common.list, &fib6_rules_ops.rules_list);
-	list_add_tail(&main_rule.common.list, &fib6_rules_ops.rules_list);
+	int err;
+
+	err = fib_default_rule_add(&fib6_rules_ops, 0,
+				   RT6_TABLE_LOCAL, FIB_RULE_PERMANENT);
+	if (err < 0)
+		return err;
+	err = fib_default_rule_add(&fib6_rules_ops, 0x7FFE, RT6_TABLE_MAIN, 0);
+	if (err < 0)
+		return err;
+	return 0;
+}
 
+void __init fib6_rules_init(void)
+{
+	BUG_ON(fib6_default_rules_init());
 	fib_rules_register(&fib6_rules_ops);
 }