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Commit 46b3a421 authored by Hannes Frederic Sowa's avatar Hannes Frederic Sowa Committed by David S. Miller
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ipv6: fib6_rules should return exact return value 



With the addition of the suppress operation
(7764a45a ("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 <stefan.tomanek@wertarbyte.de>
Cc: Hideaki YOSHIFUJI <yoshfuji@linux-ipv6.org>
Signed-off-by: default avatarHannes Frederic Sowa <hannes@stressinduktion.org>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 37830721

net/ipv6/fib6_rules.c

+11 −3
Original line number Diff line number Diff line
@@ -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 @@ static int fib6_rule_action(struct fib_rule *rule, struct flowi *flp, 
	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)