[NETLINK]: Add notification message sending interface
Adds nlmsg_notify() implementing proper notification logic. The message is multicasted to all listeners in the group. The applications the requests orignates from can request a unicast back report in which case said socket will be excluded from the multicast to avoid duplicated notifications. nlmsg_multicast() is extended to take allocation flags to allow notification in atomic contexts. Signed-off-by: Thomas Graf <tgraf@suug.ch> Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
committed by
David S. Miller
parent
2942e90050
commit
d387f6ad10
@@ -1549,6 +1549,38 @@ void netlink_queue_skip(struct nlmsghdr *nlh, struct sk_buff *skb)
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skb_pull(skb, msglen);
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}
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/**
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* nlmsg_notify - send a notification netlink message
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* @sk: netlink socket to use
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* @skb: notification message
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* @pid: destination netlink pid for reports or 0
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* @group: destination multicast group or 0
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* @report: 1 to report back, 0 to disable
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* @flags: allocation flags
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*/
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int nlmsg_notify(struct sock *sk, struct sk_buff *skb, u32 pid,
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unsigned int group, int report, gfp_t flags)
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{
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int err = 0;
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if (group) {
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int exclude_pid = 0;
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if (report) {
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atomic_inc(&skb->users);
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exclude_pid = pid;
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}
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/* errors reported via destination sk->sk_err */
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nlmsg_multicast(sk, skb, exclude_pid, group, flags);
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}
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if (report)
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err = nlmsg_unicast(sk, skb, pid);
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return err;
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}
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#ifdef CONFIG_PROC_FS
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struct nl_seq_iter {
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int link;
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@@ -1802,4 +1834,4 @@ EXPORT_SYMBOL(netlink_set_err);
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EXPORT_SYMBOL(netlink_set_nonroot);
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EXPORT_SYMBOL(netlink_unicast);
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EXPORT_SYMBOL(netlink_unregister_notifier);
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EXPORT_SYMBOL(nlmsg_notify);
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