ipv6: fib6_rules should return exact return value

PATCH In review Hannes Frederic Sowa 2 participants 2 messages Aug 1, 2013

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Networking Network drivers IPv4/IPv6

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Hannes Frederic Sowa

author

2013-08-01 06:54 UTC #0 lore raw

PATCH v2 1/1 ipv6: fib6_rules should return exact return value

With the addition of the suppress operation (7764a45a8f1fe74d4f7d301eaca2e558e7e2831a ("fib_rules: add .suppress operation") we rely on accurate error reporting of the fib_rules.actions.

fib6_rule_action always returned -EAGAIN in case we could not find a matching route and 0 if a rule was matched. This also included a match for blackhole or prohibited rule actions which could get suppressed by the new logic.

So adapt fib6_rule_action to always return the correct error code as its counterpart fib4_rule_action does. This also fixes a possiblity of nullptr-deref where we don't find a table, thus rt == NULL. Because the condition rt != ip6_null_entry still holdes it seems we could later get a nullptr bug on dereference rt->dst.

v2:
a) Fixed a brain fart in the commit msg (the rule => a table, etc). No changes to the patch.

Cc Stefan Tomanek <[email protected]>

Cc Hideaki YOSHIFUJI <[email protected]>

Signed-off-by Hannes Frederic Sowa <[email protected]>

---
 net/ipv6/fib6_rules.c | 14 +++++++++++---
 1 file changed, 11 insertions(+), 3 deletions(-)

net/ipv6/fib6_rules.c +11 -3

index e64e6a5..554a4fb 100644
@@ -55,26 +55,33 @@ static int fib6_rule_action(struct fib_rule *rule, struct flowi *flp,
 	struct fib6_table *table;
 	struct net *net = rule->fr_net;
 	pol_lookup_t lookup = arg->lookup_ptr;
+	int err = 0;
 
 	switch (rule->action) {
 	case FR_ACT_TO_TBL:
 		break;
 	case FR_ACT_UNREACHABLE:
+		err = -ENETUNREACH;
 		rt = net->ipv6.ip6_null_entry;
 		goto discard_pkt;
 	default:
 	case FR_ACT_BLACKHOLE:
+		err = -EINVAL;
 		rt = net->ipv6.ip6_blk_hole_entry;
 		goto discard_pkt;
 	case FR_ACT_PROHIBIT:
+		err = -EACCES;
 		rt = net->ipv6.ip6_prohibit_entry;
 		goto discard_pkt;
 	}
 
 	table = fib6_get_table(net, rule->table);
-	if (table)
-		rt = lookup(net, table, flp6, flags);
+	if (!table) {
+		err = -EAGAIN;
+		goto out;
+	}
 
+	rt = lookup(net, table, flp6, flags);
 	if (rt != net->ipv6.ip6_null_entry) {
 		struct fib6_rule *r = (struct fib6_rule *)rule;

@@ -101,6 +108,7 @@ static int fib6_rule_action(struct fib_rule *rule, struct flowi *flp,
 	}
 again:
 	ip6_rt_put(rt);
+	err = -EAGAIN;
 	rt = NULL;
 	goto out;

@@ -108,7 +116,7 @@ discard_pkt:
 	dst_hold(&rt->dst);
 out:
 	arg->result = rt;
-	return rt == NULL ? -EAGAIN : 0;
+	return err;
 }
 
 static bool fib6_rule_suppress(struct fib_rule *rule, struct fib_lookup_arg *arg)

Signature · 1 line

1.8.3.1

David Miller

maintainer

2013-08-01 07:26 UTC #1 lore raw

From: Hannes Frederic Sowa <[email protected]>
Date: Thu, 1 Aug 2013 08:54:47 +0200

Quoted 15 lines

With the addition of the suppress operation (7764a45a8f1fe74d4f7d301eaca2e558e7e2831a ("fib_rules: add .suppress operation") we rely on accurate error reporting of the fib_rules.actions.
fib6_rule_action always returned -EAGAIN in case we could not find a matching route and 0 if a rule was matched. This also included a match for blackhole or prohibited rule actions which could get suppressed by the new logic.
So adapt fib6_rule_action to always return the correct error code as its counterpart fib4_rule_action does. This also fixes a possiblity of nullptr-deref where we don't find a table, thus rt == NULL. Because the condition rt != ip6_null_entry still holdes it seems we could later get a nullptr bug on dereference rt->dst.

Quoted 7 lines

v2:
a) Fixed a brain fart in the commit msg (the rule => a table, etc). No changes to the patch.
Cc Stefan Tomanek <[email protected]>
Cc Hideaki YOSHIFUJI <[email protected]>
Signed-off-by Hannes Frederic Sowa <[email protected]>

Looks good, applied, thanks.