[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/core/rtnetlink.c b/net/core/rtnetlink.c
index 02f3c79..50d6cb4 100644
--- a/net/core/rtnetlink.c
+++ b/net/core/rtnetlink.c
@@ -273,6 +273,25 @@
a->tx_compressed = b->tx_compressed;
};
+static inline size_t if_nlmsg_size(int iwbuflen)
+{
+ return NLMSG_ALIGN(sizeof(struct ifinfomsg))
+ + nla_total_size(IFNAMSIZ) /* IFLA_IFNAME */
+ + nla_total_size(IFNAMSIZ) /* IFLA_QDISC */
+ + nla_total_size(sizeof(struct rtnl_link_ifmap))
+ + nla_total_size(sizeof(struct rtnl_link_stats))
+ + nla_total_size(MAX_ADDR_LEN) /* IFLA_ADDRESS */
+ + nla_total_size(MAX_ADDR_LEN) /* IFLA_BROADCAST */
+ + nla_total_size(4) /* IFLA_TXQLEN */
+ + nla_total_size(4) /* IFLA_WEIGHT */
+ + nla_total_size(4) /* IFLA_MTU */
+ + nla_total_size(4) /* IFLA_LINK */
+ + nla_total_size(4) /* IFLA_MASTER */
+ + nla_total_size(1) /* IFLA_OPERSTATE */
+ + nla_total_size(1) /* IFLA_LINKMODE */
+ + nla_total_size(iwbuflen);
+}
+
static int rtnl_fill_ifinfo(struct sk_buff *skb, struct net_device *dev,
void *iwbuf, int iwbuflen, int type, u32 pid,
u32 seq, u32 change, unsigned int flags)
@@ -558,7 +577,7 @@
struct sk_buff *nskb;
char *iw_buf = NULL, *iw = NULL;
int iw_buf_len = 0;
- int err, payload;
+ int err;
err = nlmsg_parse(nlh, sizeof(*ifm), tb, IFLA_MAX, ifla_policy);
if (err < 0)
@@ -587,9 +606,7 @@
}
#endif /* CONFIG_NET_WIRELESS_RTNETLINK */
- payload = NLMSG_ALIGN(sizeof(struct ifinfomsg) +
- nla_total_size(iw_buf_len));
- nskb = nlmsg_new(nlmsg_total_size(payload), GFP_KERNEL);
+ nskb = nlmsg_new(if_nlmsg_size(iw_buf_len), GFP_KERNEL);
if (nskb == NULL) {
err = -ENOBUFS;
goto errout;
@@ -597,10 +614,8 @@
err = rtnl_fill_ifinfo(nskb, dev, iw, iw_buf_len, RTM_NEWLINK,
NETLINK_CB(skb).pid, nlh->nlmsg_seq, 0, 0);
- if (err <= 0) {
- kfree_skb(nskb);
- goto errout;
- }
+ /* failure impilies BUG in if_nlmsg_size or wireless_rtnetlink_get */
+ BUG_ON(err < 0);
err = rtnl_unicast(nskb, NETLINK_CB(skb).pid);
errout:
@@ -639,15 +654,13 @@
struct sk_buff *skb;
int err = -ENOBUFS;
- skb = nlmsg_new(NLMSG_GOODSIZE, GFP_KERNEL);
+ skb = nlmsg_new(if_nlmsg_size(0), GFP_KERNEL);
if (skb == NULL)
goto errout;
err = rtnl_fill_ifinfo(skb, dev, NULL, 0, type, 0, 0, change, 0);
- if (err < 0) {
- kfree_skb(skb);
- goto errout;
- }
+ /* failure implies BUG in if_nlmsg_size() */
+ BUG_ON(err < 0);
err = rtnl_notify(skb, 0, RTNLGRP_LINK, NULL, GFP_KERNEL);
errout: