[NET]: Fix fib_rules compatibility breakage

Based upon a patch from Patrick McHardy.

The fib_rules netlink attribute policy introduced in 2.6.19 broke
userspace compatibilty. When specifying a rule with "from all"
or "to all", iproute adds a zero byte long netlink attribute,
but the policy requires all addresses to have a size equal to
sizeof(struct in_addr)/sizeof(struct in6_addr), resulting in a
validation error.

Check attribute length of FRA_SRC/FRA_DST in the generic framework
by letting the family specific rules implementation provide the
length of an address. Report an error if address length is non
zero but no address attribute is provided. Fix actual bug by
checking address length for non-zero instead of relying on
availability of attribute.

Signed-off-by: Thomas Graf <tgraf@suug.ch>
Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 5 insertions, 9 deletions

diff --git a/net/ipv6/fib6_rules.c b/net/ipv6/fib6_rules.c
index 0862809..ea3035b 100644
--- a/net/ipv6/fib6_rules.c
+++ b/net/ipv6/fib6_rules.c
@@ -131,8 +131,6 @@ static int fib6_rule_match(struct fib_rule *rule, struct flowi *fl, int flags)
 
 static struct nla_policy fib6_rule_policy[FRA_MAX+1] __read_mostly = {
 	FRA_GENERIC_POLICY,
-	[FRA_SRC]	= { .len = sizeof(struct in6_addr) },
-	[FRA_DST]	= { .len = sizeof(struct in6_addr) },
 };
 
 static int fib6_rule_configure(struct fib_rule *rule, struct sk_buff *skb,
@@ -142,9 +140,6 @@ static int fib6_rule_configure(struct fib_rule *rule, struct sk_buff *skb,
 	int err = -EINVAL;
 	struct fib6_rule *rule6 = (struct fib6_rule *) rule;
 
-	if (frh->src_len > 128 || frh->dst_len > 128)
-		goto errout;
-
 	if (rule->action == FR_ACT_TO_TBL) {
 		if (rule->table == RT6_TABLE_UNSPEC)
 			goto errout;
@@ -155,11 +150,11 @@ static int fib6_rule_configure(struct fib_rule *rule, struct sk_buff *skb,
 		}
 	}
 
-	if (tb[FRA_SRC])
+	if (frh->src_len)
 		nla_memcpy(&rule6->src.addr, tb[FRA_SRC],
 			   sizeof(struct in6_addr));
 
-	if (tb[FRA_DST])
+	if (frh->dst_len)
 		nla_memcpy(&rule6->dst.addr, tb[FRA_DST],
 			   sizeof(struct in6_addr));
 
@@ -186,11 +181,11 @@ static int fib6_rule_compare(struct fib_rule *rule, struct fib_rule_hdr *frh,
 	if (frh->tos && (rule6->tclass != frh->tos))
 		return 0;
 
-	if (tb[FRA_SRC] &&
+	if (frh->src_len &&
 	    nla_memcmp(tb[FRA_SRC], &rule6->src.addr, sizeof(struct in6_addr)))
 		return 0;
 
-	if (tb[FRA_DST] &&
+	if (frh->dst_len &&
 	    nla_memcmp(tb[FRA_DST], &rule6->dst.addr, sizeof(struct in6_addr)))
 		return 0;
 
@@ -240,6 +235,7 @@ static size_t fib6_rule_nlmsg_payload(struct fib_rule *rule)
 static struct fib_rules_ops fib6_rules_ops = {
 	.family			= AF_INET6,
 	.rule_size		= sizeof(struct fib6_rule),
+	.addr_size		= sizeof(struct in6_addr),
 	.action			= fib6_rule_action,
 	.match			= fib6_rule_match,
 	.configure		= fib6_rule_configure,