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netlink: add NETLINK_BROADCAST_ERROR socket option

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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: Pablo Neira Ayuso <pablo@netfilter.org>
Acked-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Pablo Neira Ayuso 2009-02-18 01:40:43 +00:00 committed by David S. Miller
parent 2d96cf8cdf
commit be0c22a46c
2 changed files with 24 additions and 2 deletions
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1
include/linux/netlink.h
View File

@ -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
{

25
net/netlink/af_netlink.c
View File

@ -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)
{
@ -995,12 +996,15 @@ 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);
p->delivery_failure = 1;
if (nlk->flags & NETLINK_BROADCAST_SEND_ERROR)
p->delivery_failure = 1;
} else {
p->congested |= val;
p->delivered = 1;
@ -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;
}