From be0c22a46cfb79ab2342bb28fde99afa94ef868e Mon Sep 17 00:00:00 2001 From: Pablo Neira Ayuso Date: Wed, 18 Feb 2009 01:40:43 +0000 Subject: [PATCH] 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: Pablo Neira Ayuso Acked-by: Patrick McHardy Signed-off-by: David S. Miller --- include/linux/netlink.h | 1 + net/netlink/af_netlink.c | 25 +++++++++++++++++++++++-- 2 files changed, 24 insertions(+), 2 deletions(-) diff --git a/include/linux/netlink.h b/include/linux/netlink.h index 51b09a1f46c3..1e6bf995435c 100644 --- a/include/linux/netlink.h +++ b/include/linux/netlink.h @@ -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 { diff --git a/net/netlink/af_netlink.c b/net/netlink/af_netlink.c index 6ee69c27f806..ed587be1e1c2 100644 --- a/net/netlink/af_netlink.c +++ b/net/netlink/af_netlink.c @@ -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; } -- 2.30.2