netdev - [PATCH] netlink.7: describe netlink socket options

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Date:	Fri, 10 Jun 2016 13:28:37 -0700
From:	Andrey Vagin <avagin@...nvz.org>
To:	mtk.manpages@...il.com
Cc:	netdev@...r.kernel.org, linux-man@...r.kernel.org,
	Andrey Vagin <avagin@...nvz.org>,
	Kir Kolyshkin <kir@...nvz.org>,
	Herbert Xu <herbert@...dor.apana.org.au>,
	Patrick McHardy <kaber@...sh.net>,
	Christophe Ricard <christophe.ricard@...il.com>,
	Nicolas Dichtel <nicolas.dichtel@...nd.com>
Subject: [PATCH] netlink.7: describe netlink socket options

Cc: Kir Kolyshkin <kir@...nvz.org>
Cc: Michael Kerrisk <mtk.manpages@...il.com>
Cc: Herbert Xu <herbert@...dor.apana.org.au>
Cc: Patrick McHardy <kaber@...sh.net>
Cc: Christophe Ricard <christophe.ricard@...il.com>
Cc: Nicolas Dichtel <nicolas.dichtel@...nd.com>
Signed-off-by: Andrey Vagin <avagin@...nvz.org>
---
 man7/netlink.7 | 75 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 75 insertions(+)

diff --git a/man7/netlink.7 b/man7/netlink.7
index 513f854..b4848df 100644
--- a/man7/netlink.7
+++ b/man7/netlink.7
@@ -368,6 +368,81 @@ and
 .BR NETLINK_SELINUX
 groups allow other users to receive messages.
 No groups allow other users to send messages.
+
+.SS Socket options
+To set or get a netlink socket option, call
+.BR getsockopt (2)
+to read or
+.BR setsockopt (2)
+to write the option with the option level argument set to
+.BR SOL_NETLINK .
+Unless otherwise noted,
+.I optval
+is a pointer to an
+.IR int .
+.TP
+.BR NETLINK_PKTINFO " (since Linux 2.6.14)"
+Enable
+.B nl_pktinfo
+control messages for received packets to get the extended
+destination group number.
+.TP
+.BR NETLINK_ADD_MEMBERSHIP ,\  NETLINK_DROP_MEMBERSHIP " (since Linux 2.6.14)"
+Join/leave a group specified by
+.IR optval .
+.\"	commit 9a4595bc7e67962f13232ee55a64e063062c3a99
+.\"	Author: Patrick McHardy <kaber@...sh.net>
+.TP
+.BR NETLINK_LIST_MEMBERSHIPS " (since Linux 4.2)"
+Retrieve all groups a socket is a member of.
+.I optval
+is a pointer to
+.B __u32
+and
+.I optlen
+is the size of the array. The array is filled with the full membership set of the
+socket, and the required array size is returned in
+.I optlen.
+.\"	commit b42be38b2778eda2237fc759e55e3b698b05b315
+.\"	Author: David Herrmann <dh.herrmann@...il.com>
+.TP
+.BR NETLINK_BROADCAST_ERROR " (since Linux 2.6.30)"
+When not set,
+.B netlink_broadcast()
+only reports
+.B ESRCH
+errors and silently ignore
+.B NOBUFS
+errors.
+.\"	commit be0c22a46cfb79ab2342bb28fde99afa94ef868e
+.\"	Author: Pablo Neira Ayuso <pablo@...filter.org>
+.TP
+.BR NETLINK_NO_ENOBUFS " (since Linux 2.6.30)"
+This flag can be used by unicast and broadcast listeners to avoid receiving
+.B ENOBUFS
+errors.
+.\"	commit 38938bfe3489394e2eed5e40c9bb8f66a2ce1405
+.\"	Author: Pablo Neira Ayuso <pablo@...filter.org>
+.TP
+.BR NETLINK_LISTEN_ALL_NSID " (since Linux 4.2)"
+When set, this socket will receive netlink notifications from all network namespaces that
+have an
+.I nsid
+assigned into the network namespace where the socket has been opened. The
+.I nsid
+is sent to user space via an ancillary data.
+.\"	commit 59324cf35aba5336b611074028777838a963d03b
+.\"	Author: Nicolas Dichtel <nicolas.dichtel@...nd.com>
+.TP
+.BR NETLINK_CAP_ACK " (since Linux 4.2)"
+The kernel may fail to allocate the necessary room for the acknowledgment
+message back to userspace. This option trims off the payload of the original
+netlink message.
+The netlink message header is still included, so the user can guess from the
+sequence number what is the message that has triggered the acknowledgment.
+.\"	commit 0a6a3a23ea6efde079a5b77688541a98bf202721
+.\"	Author: Christophe Ricard <christophe.ricard@...il.com>
+
 .SH VERSIONS
 The socket interface to netlink is a new feature of Linux 2.2.
 
-- 
2.5.5