[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>
diff --git a/net/ipv4/fib_semantics.c b/net/ipv4/fib_semantics.c
index 884d176..e63b8a9 100644
--- a/net/ipv4/fib_semantics.c
+++ b/net/ipv4/fib_semantics.c
@@ -273,25 +273,49 @@
return -1;
}
+static inline size_t fib_nlmsg_size(struct fib_info *fi)
+{
+ size_t payload = NLMSG_ALIGN(sizeof(struct rtmsg))
+ + nla_total_size(4) /* RTA_TABLE */
+ + nla_total_size(4) /* RTA_DST */
+ + nla_total_size(4) /* RTA_PRIORITY */
+ + nla_total_size(4); /* RTA_PREFSRC */
+
+ /* space for nested metrics */
+ payload += nla_total_size((RTAX_MAX * nla_total_size(4)));
+
+ if (fi->fib_nhs) {
+ /* Also handles the special case fib_nhs == 1 */
+
+ /* each nexthop is packed in an attribute */
+ size_t nhsize = nla_total_size(sizeof(struct rtnexthop));
+
+ /* may contain flow and gateway attribute */
+ nhsize += 2 * nla_total_size(4);
+
+ /* all nexthops are packed in a nested attribute */
+ payload += nla_total_size(fi->fib_nhs * nhsize);
+ }
+
+ return payload;
+}
+
void rtmsg_fib(int event, __be32 key, struct fib_alias *fa,
int dst_len, u32 tb_id, struct nl_info *info)
{
struct sk_buff *skb;
- int payload = sizeof(struct rtmsg) + 256;
u32 seq = info->nlh ? info->nlh->nlmsg_seq : 0;
int err = -ENOBUFS;
- skb = nlmsg_new(nlmsg_total_size(payload), GFP_KERNEL);
+ skb = nlmsg_new(fib_nlmsg_size(fa->fa_info), GFP_KERNEL);
if (skb == NULL)
goto errout;
err = fib_dump_info(skb, info->pid, seq, event, tb_id,
fa->fa_type, fa->fa_scope, key, dst_len,
fa->fa_tos, fa->fa_info, 0);
- if (err < 0) {
- kfree_skb(skb);
- goto errout;
- }
+ /* failure implies BUG in fib_nlmsg_size() */
+ BUG_ON(err < 0);
err = rtnl_notify(skb, info->pid, RTNLGRP_IPV4_ROUTE,
info->nlh, GFP_KERNEL);