[NETLINK]: Do precise netlink message allocations where possible

Account for the netlink message header size directly in nlmsg_new()
instead of relying on the caller calculate it correctly.

Replaces error handling of message construction functions when
constructing notifications with bug traps since a failure implies
a bug in calculating the size of the skb.

Signed-off-by: Thomas Graf <tgraf@suug.ch>
Acked-by: Paul Moore <paul.moore@hp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 8 insertions, 0 deletions

diff --git a/net/ipv4/fib_rules.c b/net/ipv4/fib_rules.c
index fd4a8cd4c06e..b837c33e0404 100644
--- a/net/ipv4/fib_rules.c
+++ b/net/ipv4/fib_rules.c
@@ -299,6 +299,13 @@ static u32 fib4_rule_default_pref(void)
         return 0;
 }
 
+static size_t fib4_rule_nlmsg_payload(struct fib_rule *rule)
+{
+        return nla_total_size(4) /* dst */
+               + nla_total_size(4) /* src */
+               + nla_total_size(4); /* flow */
+}
+
 static struct fib_rules_ops fib4_rules_ops = {
         .family         = AF_INET,
         .rule_size      = sizeof(struct fib4_rule),
@@ -308,6 +315,7 @@ static struct fib_rules_ops fib4_rules_ops = {
         .compare        = fib4_rule_compare,
         .fill           = fib4_rule_fill,
         .default_pref   = fib4_rule_default_pref,
+        .nlmsg_payload  = fib4_rule_nlmsg_payload,
         .nlgroup        = RTNLGRP_IPV4_RULE,
         .policy         = fib4_rule_policy,
         .rules_list     = &fib4_rules,