[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, 6 insertions, 8 deletions

diff --git a/net/ipv4/fib_rules.c b/net/ipv4/fib_rules.c
index b837c33e040..c660c074c76 100644
--- a/net/ipv4/fib_rules.c
+++ b/net/ipv4/fib_rules.c
@@ -171,8 +171,6 @@ static struct fib_table *fib_empty_table(void)
 
 static struct nla_policy fib4_rule_policy[FRA_MAX+1] __read_mostly = {
         FRA_GENERIC_POLICY,
-        [FRA_SRC]       = { .type = NLA_U32 },
-        [FRA_DST]       = { .type = NLA_U32 },
         [FRA_FLOW]      = { .type = NLA_U32 },
 };
 
@@ -183,8 +181,7 @@ static int fib4_rule_configure(struct fib_rule *rule, struct sk_buff *skb,
         int err = -EINVAL;
         struct fib4_rule *rule4 = (struct fib4_rule *) rule;
 
-        if (frh->src_len > 32 || frh->dst_len > 32 ||
-            (frh->tos & ~IPTOS_TOS_MASK))
+        if (frh->tos & ~IPTOS_TOS_MASK)
                 goto errout;
 
         if (rule->table == RT_TABLE_UNSPEC) {
@@ -201,10 +198,10 @@ static int fib4_rule_configure(struct fib_rule *rule, struct sk_buff *skb,
                 }
         }
 
-        if (tb[FRA_SRC])
+        if (frh->src_len)
                 rule4->src = nla_get_be32(tb[FRA_SRC]);
 
-        if (tb[FRA_DST])
+        if (frh->dst_len)
                 rule4->dst = nla_get_be32(tb[FRA_DST]);
 
 #ifdef CONFIG_NET_CLS_ROUTE
@@ -242,10 +239,10 @@ static int fib4_rule_compare(struct fib_rule *rule, struct fib_rule_hdr *frh,
                 return 0;
 #endif
 
-        if (tb[FRA_SRC] && (rule4->src != nla_get_be32(tb[FRA_SRC])))
+        if (frh->src_len && (rule4->src != nla_get_be32(tb[FRA_SRC])))
                 return 0;
 
-        if (tb[FRA_DST] && (rule4->dst != nla_get_be32(tb[FRA_DST])))
+        if (frh->dst_len && (rule4->dst != nla_get_be32(tb[FRA_DST])))
                 return 0;
 
         return 1;
@@ -309,6 +306,7 @@ static size_t fib4_rule_nlmsg_payload(struct fib_rule *rule)
 static struct fib_rules_ops fib4_rules_ops = {
         .family         = AF_INET,
         .rule_size      = sizeof(struct fib4_rule),
+        .addr_size      = sizeof(u32),
         .action         = fib4_rule_action,
         .match          = fib4_rule_match,
         .configure      = fib4_rule_configure,