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Commit 339bf98f authored by Thomas Graf's avatar Thomas Graf Committed by David S. Miller
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[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: default avatarThomas Graf <tgraf@suug.ch>
Acked-by: default avatarPaul Moore <paul.moore@hp.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent a94f723d

include/linux/netlink.h

+1 −0
Original line number Diff line number Diff line
@@ -174,6 +174,7 @@ int netlink_sendskb(struct sock *sk, struct sk_buff *skb, int protocol); 
 */

#define NLMSG_GOODORDER 0

#define NLMSG_GOODSIZE (SKB_MAX_ORDER(0, NLMSG_GOODORDER))

#define NLMSG_DEFAULT_SIZE (NLMSG_GOODSIZE - NLMSG_HDRLEN)





struct netlink_callback

include/net/fib_rules.h

+1 −0
Original line number Diff line number Diff line
@@ -52,6 +52,7 @@ struct fib_rules_ops 
					struct nlmsghdr *,

					struct fib_rule_hdr *);

	u32			(*default_pref)(void);

	size_t			(*nlmsg_payload)(struct fib_rule *);



	int			nlgroup;

	struct nla_policy	*policy;

include/net/netlink.h

+5 −4
Original line number Diff line number Diff line
@@ -500,14 +500,15 @@ static inline struct nlmsghdr *nlmsg_put_answer(struct sk_buff *skb, 


/**

 * nlmsg_new - Allocate a new netlink message

 * @size: maximum size of message

 * @payload: size of the message payload

 * @flags: the type of memory to allocate.

 *

 * Use NLMSG_GOODSIZE if size isn't know and you need a good default size.

 * Use NLMSG_DEFAULT_SIZE if the size of the payload isn't known

 * and a good default is needed.

 */

static inline struct sk_buff *nlmsg_new(int size, gfp_t flags)

static inline struct sk_buff *nlmsg_new(size_t payload, gfp_t flags)

{

	return alloc_skb(size, flags);

	return alloc_skb(nlmsg_total_size(payload), flags);

}



/**

kernel/taskstats.c

+1 −2
Original line number Diff line number Diff line
@@ -77,8 +77,7 @@ static int prepare_reply(struct genl_info *info, u8 cmd, struct sk_buff **skbp, 
	/*

	 * If new attributes are added, please revisit this allocation

	 */

	size = nlmsg_total_size(genlmsg_total_size(size));

	skb = nlmsg_new(size, GFP_KERNEL);

	skb = nlmsg_new(genlmsg_total_size(size), GFP_KERNEL);

	if (!skb)

		return -ENOMEM;

net/bridge/br_netlink.c

+15 −6
Original line number Diff line number Diff line
@@ -15,6 +15,18 @@ 
#include <net/netlink.h>

#include "br_private.h"



static inline size_t br_nlmsg_size(void)

{

	return NLMSG_ALIGN(sizeof(struct ifinfomsg))

	       + nla_total_size(IFNAMSIZ) /* IFLA_IFNAME */

	       + nla_total_size(MAX_ADDR_LEN) /* IFLA_ADDRESS */

	       + nla_total_size(4) /* IFLA_MASTER */

	       + nla_total_size(4) /* IFLA_MTU */

	       + nla_total_size(4) /* IFLA_LINK */

	       + nla_total_size(1) /* IFLA_OPERSTATE */

	       + nla_total_size(1); /* IFLA_PROTINFO */

}



/*

 * Create one netlink message for one interface

 * Contains port and master info as well as carrier and bridge state.
@@ -77,19 +89,16 @@ static int br_fill_ifinfo(struct sk_buff *skb, const struct net_bridge_port *por 
void br_ifinfo_notify(int event, struct net_bridge_port *port)

{

	struct sk_buff *skb;

	int payload = sizeof(struct ifinfomsg) + 128;

	int err = -ENOBUFS;



	pr_debug("bridge notify event=%d\n", event);

	skb = nlmsg_new(nlmsg_total_size(payload), GFP_ATOMIC);

	skb = nlmsg_new(br_nlmsg_size(), GFP_ATOMIC);

	if (skb == NULL)

		goto errout;



	err = br_fill_ifinfo(skb, port, 0, 0, event, 0);

	if (err < 0) {

		kfree_skb(skb);

		goto errout;

	}

	/* failure implies BUG in br_nlmsg_size() */

	BUG_ON(err < 0);



	err = rtnl_notify(skb, 0, RTNLGRP_LINK, NULL, GFP_ATOMIC);

errout: