Commit be0c22a4 authored by Pablo Neira Ayuso's avatar Pablo Neira Ayuso Committed by David S. Miller
Browse files

netlink: add NETLINK_BROADCAST_ERROR socket option 



This patch adds NETLINK_BROADCAST_ERROR which is a netlink
socket option that the listener can set to make netlink_broadcast()
return errors in the delivery to the caller. This option is useful
if the caller of netlink_broadcast() do something with the result
of the message delivery, like in ctnetlink where it drops a network
packet if the event delivery failed, this is used to enable reliable
logging and state-synchronization. If this socket option is not set,
netlink_broadcast() only reports ESRCH errors and silently ignore
ENOBUFS errors, which is what most netlink_broadcast() callers
should do.

This socket option is based on a suggestion from Patrick McHardy.
Patrick McHardy can exchange this patch for a beer from me ;).

Signed-off-by: default avatarPablo Neira Ayuso <pablo@netfilter.org>
Acked-by: default avatarPatrick McHardy <kaber@trash.net>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 2d96cf8c

include/linux/netlink.h

+1 −0
Original line number Diff line number Diff line
@@ -103,6 +103,7 @@ struct nlmsgerr 
#define NETLINK_ADD_MEMBERSHIP	1

#define NETLINK_DROP_MEMBERSHIP	2

#define NETLINK_PKTINFO		3

#define NETLINK_BROADCAST_ERROR	4



struct nl_pktinfo

{

net/netlink/af_netlink.c

+23 −2
Original line number Diff line number Diff line
@@ -85,6 +85,7 @@ struct netlink_sock { 


#define NETLINK_KERNEL_SOCKET	0x1

#define NETLINK_RECV_PKTINFO	0x2

#define NETLINK_BROADCAST_SEND_ERROR	0x4



static inline struct netlink_sock *nlk_sk(struct sock *sk)

{
@@ -995,11 +996,14 @@ static inline int do_one_broadcast(struct sock *sk, 
		netlink_overrun(sk);

		/* Clone failed. Notify ALL listeners. */

		p->failure = 1;

		if (nlk->flags & NETLINK_BROADCAST_SEND_ERROR)

			p->delivery_failure = 1;

	} else if (sk_filter(sk, p->skb2)) {

		kfree_skb(p->skb2);

		p->skb2 = NULL;

	} else if ((val = netlink_broadcast_deliver(sk, p->skb2)) < 0) {

		netlink_overrun(sk);

		if (nlk->flags & NETLINK_BROADCAST_SEND_ERROR)

			p->delivery_failure = 1;

	} else {

		p->congested |= val;
@@ -1048,7 +1052,7 @@ int netlink_broadcast(struct sock *ssk, struct sk_buff *skb, u32 pid, 
	if (info.skb2)

		kfree_skb(info.skb2);



	if (info.delivery_failure || info.failure)

	if (info.delivery_failure)

		return -ENOBUFS;



	if (info.delivered) {
@@ -1163,6 +1167,13 @@ static int netlink_setsockopt(struct socket *sock, int level, int optname, 
		err = 0;

		break;

	}

	case NETLINK_BROADCAST_ERROR:

		if (val)

			nlk->flags |= NETLINK_BROADCAST_SEND_ERROR;

		else

			nlk->flags &= ~NETLINK_BROADCAST_SEND_ERROR;

		err = 0;

		break;

	default:

		err = -ENOPROTOOPT;

	}
@@ -1195,6 +1206,16 @@ static int netlink_getsockopt(struct socket *sock, int level, int optname, 
			return -EFAULT;

		err = 0;

		break;

	case NETLINK_BROADCAST_ERROR:

		if (len < sizeof(int))

			return -EINVAL;

		len = sizeof(int);

		val = nlk->flags & NETLINK_BROADCAST_SEND_ERROR ? 1 : 0;

		if (put_user(len, optlen) ||

		    put_user(val, optval))

			return -EFAULT;

		err = 0;

		break;

	default:

		err = -ENOPROTOOPT;

	}

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