1 files changed, 85 insertions, 3 deletions

diff --git a/net/core/fib_rules.c b/net/core/fib_rules.c
index fdf05af..0d8bb2e 100644
--- a/net/core/fib_rules.c
+++ b/net/core/fib_rules.c
@@ -132,10 +132,23 @@ int fib_rules_lookup(struct fib_rules_ops *ops, struct flowi *fl,
 	rcu_read_lock();
 
 	list_for_each_entry_rcu(rule, ops->rules_list, list) {
+jumped:
 		if (!fib_rule_match(rule, ops, fl, flags))
 			continue;
 
-		err = ops->action(rule, fl, flags, arg);
+		if (rule->action == FR_ACT_GOTO) {
+			struct fib_rule *target;
+
+			target = rcu_dereference(rule->ctarget);
+			if (target == NULL) {
+				continue;
+			} else {
+				rule = target;
+				goto jumped;
+			}
+		} else
+			err = ops->action(rule, fl, flags, arg);
+
 		if (err != -EAGAIN) {
 			fib_rule_get(rule);
 			arg->rule = rule;
@@ -180,7 +193,7 @@ static int fib_nl_newrule(struct sk_buff *skb, struct nlmsghdr* nlh, void *arg)
 	struct fib_rules_ops *ops = NULL;
 	struct fib_rule *rule, *r, *last = NULL;
 	struct nlattr *tb[FRA_MAX+1];
-	int err = -EINVAL;
+	int err = -EINVAL, unresolved = 0;
 
 	if (nlh->nlmsg_len < nlmsg_msg_size(sizeof(*frh)))
 		goto errout;
@@ -237,6 +250,28 @@ static int fib_nl_newrule(struct sk_buff *skb, struct nlmsghdr* nlh, void *arg)
 	if (!rule->pref && ops->default_pref)
 		rule->pref = ops->default_pref();
 
+	err = -EINVAL;
+	if (tb[FRA_GOTO]) {
+		if (rule->action != FR_ACT_GOTO)
+			goto errout_free;
+
+		rule->target = nla_get_u32(tb[FRA_GOTO]);
+		/* Backward jumps are prohibited to avoid endless loops */
+		if (rule->target <= rule->pref)
+			goto errout_free;
+
+		list_for_each_entry(r, ops->rules_list, list) {
+			if (r->pref == rule->target) {
+				rule->ctarget = r;
+				break;
+			}
+		}
+
+		if (rule->ctarget == NULL)
+			unresolved = 1;
+	} else if (rule->action == FR_ACT_GOTO)
+		goto errout_free;
+
 	err = ops->configure(rule, skb, nlh, frh, tb);
 	if (err < 0)
 		goto errout_free;
@@ -249,6 +284,28 @@ static int fib_nl_newrule(struct sk_buff *skb, struct nlmsghdr* nlh, void *arg)
 
 	fib_rule_get(rule);
 
+	if (ops->unresolved_rules) {
+		/*
+		 * There are unresolved goto rules in the list, check if
+		 * any of them are pointing to this new rule.
+		 */
+		list_for_each_entry(r, ops->rules_list, list) {
+			if (r->action == FR_ACT_GOTO &&
+			    r->target == rule->pref) {
+				BUG_ON(r->ctarget != NULL);
+				rcu_assign_pointer(r->ctarget, rule);
+				if (--ops->unresolved_rules == 0)
+					break;
+			}
+		}
+	}
+
+	if (rule->action == FR_ACT_GOTO)
+		ops->nr_goto_rules++;
+
+	if (unresolved)
+		ops->unresolved_rules++;
+
 	if (last)
 		list_add_rcu(&rule->list, &last->list);
 	else
@@ -269,7 +326,7 @@ static int fib_nl_delrule(struct sk_buff *skb, struct nlmsghdr* nlh, void *arg)
 {
 	struct fib_rule_hdr *frh = nlmsg_data(nlh);
 	struct fib_rules_ops *ops = NULL;
-	struct fib_rule *rule;
+	struct fib_rule *rule, *tmp;
 	struct nlattr *tb[FRA_MAX+1];
 	int err = -EINVAL;
 
@@ -322,6 +379,25 @@ static int fib_nl_delrule(struct sk_buff *skb, struct nlmsghdr* nlh, void *arg)
 		}
 
 		list_del_rcu(&rule->list);
+
+		if (rule->action == FR_ACT_GOTO)
+			ops->nr_goto_rules--;
+
+		/*
+		 * Check if this rule is a target to any of them. If so,
+		 * disable them. As this operation is eventually very
+		 * expensive, it is only performed if goto rules have
+		 * actually been added.
+		 */
+		if (ops->nr_goto_rules > 0) {
+			list_for_each_entry(tmp, ops->rules_list, list) {
+				if (tmp->ctarget == rule) {
+					rcu_assign_pointer(tmp->ctarget, NULL);
+					ops->unresolved_rules++;
+				}
+			}
+		}
+
 		synchronize_rcu();
 		notify_rule_change(RTM_DELRULE, rule, ops, nlh,
 				   NETLINK_CB(skb).pid);
@@ -371,6 +447,9 @@ static int fib_nl_fill_rule(struct sk_buff *skb, struct fib_rule *rule,
 	frh->action = rule->action;
 	frh->flags = rule->flags;
 
+	if (rule->action == FR_ACT_GOTO && rule->ctarget == NULL)
+		frh->flags |= FIB_RULE_UNRESOLVED;
+
 	if (rule->ifname[0])
 		NLA_PUT_STRING(skb, FRA_IFNAME, rule->ifname);
 
@@ -383,6 +462,9 @@ static int fib_nl_fill_rule(struct sk_buff *skb, struct fib_rule *rule,
 	if (rule->mark_mask || rule->mark)
 		NLA_PUT_U32(skb, FRA_FWMASK, rule->mark_mask);
 
+	if (rule->target)
+		NLA_PUT_U32(skb, FRA_GOTO, rule->target);
+
 	if (ops->fill(rule, skb, nlh, frh) < 0)
 		goto nla_put_failure;