[PATCH net-next v6 04/15] ethtool: introduce ethtool netlink interface

[Michal Kubecek <mkubecek@suse.cz>]

Basic genetlink and init infrastructure for the netlink interface, register
genetlink family "ethtool". Add CONFIG_ETHTOOL_NETLINK Kconfig option to
make the build optional. Add initial overall interface description into
Documentation/networking/ethtool-netlink.txt, further patches will add more
detailed information.

Signed-off-by: Michal Kubecek <mkubecek@suse.cz>
---
 Documentation/networking/ethtool-netlink.txt | 208 +++++++++++++++++++
 include/linux/ethtool_netlink.h              |   9 +
 include/uapi/linux/ethtool_netlink.h         |  36 ++++
 net/Kconfig                                  |   8 +
 net/ethtool/Makefile                         |   6 +-
 net/ethtool/netlink.c                        |  33 +++
 net/ethtool/netlink.h                        |  10 +
 7 files changed, 309 insertions(+), 1 deletion(-)
 create mode 100644 Documentation/networking/ethtool-netlink.txt
 create mode 100644 include/linux/ethtool_netlink.h
 create mode 100644 include/uapi/linux/ethtool_netlink.h
 create mode 100644 net/ethtool/netlink.c
 create mode 100644 net/ethtool/netlink.h

diff --git a/Documentation/networking/ethtool-netlink.txt b/Documentation/networking/ethtool-netlink.txt
new file mode 100644
index 000000000000..97c369aa290b
--- /dev/null
+++ b/Documentation/networking/ethtool-netlink.txt
@@ -0,0 +1,208 @@
+                        Netlink interface for ethtool
+                        =============================
+
+
+Basic information
+-----------------
+
+Netlink interface for ethtool uses generic netlink family "ethtool" (userspace
+application should use macros ETHTOOL_GENL_NAME and ETHTOOL_GENL_VERSION
+defined in <linux/ethtool_netlink.h> uapi header). This family does not use
+a specific header, all information in requests and replies is passed using
+netlink attributes.
+
+The ethtool netlink interface uses extended ACK for error and warning
+reporting, userspace application developers are encouraged to make these
+messages available to user in a suitable way.
+
+Requests can be divided into three categories: "get" (retrieving information),
+"set" (setting parameters) and "action" (invoking an action).
+
+All "set" and "action" type requests require admin privileges (CAP_NET_ADMIN
+in the namespace). Most "get" type requests are allowed for anyone but there
+are exceptions (where the response contains sensitive information). In some
+cases, the request as such is allowed for anyone but unprivileged users have
+attributes with sensitive information (e.g. wake-on-lan password) omitted.
+
+
+Conventions
+-----------
+
+Attributes which represent a boolean value usually use u8 type so that we can
+distinguish three states: "on", "off" and "not present" (meaning the
+information is not available in "get" requests or value is not to be changed
+in "set" requests). For these attributes, the "true" value should be passed as
+number 1 but any non-zero value should be understood as "true" by recipient.
+
+In the message structure descriptions below, if an attribute name is suffixed
+with "+", parent nest can contain multiple attributes of the same type. This
+implements an array of entries.
+
+
+Request header
+--------------
+
+Each request or reply message contains a nested attribute with common header.
+Structure of this header is
+
+    ETHTOOL_A_HEADER_DEV_INDEX	(u32)		device ifindex
+    ETHTOOL_A_HEADER_DEV_NAME	(string)	device name
+    ETHTOOL_A_HEADER_INFOMASK	(u32)		info mask
+    ETHTOOL_A_HEADER_GFLAGS	(u32)		flags common for all requests
+    ETHTOOL_A_HEADER_RFLAGS	(u32)		request specific flags
+
+ETHTOOL_A_HEADER_DEV_INDEX and ETHTOOL_A_HEADER_DEV_NAME identify the device
+message relates to. One of them is sufficient in requests, if both are used,
+they must identify the same device. Some requests, e.g. global string sets, do
+not require device identification. Most GET requests also allow dump requests
+without device identification to query the same information for all devices
+providing it (each device in a separate message).
+
+Optional info mask allows to ask only for a part of data provided by GET
+request types. If omitted or zero, all data is returned. The two flag bitmaps
+allow enabling requestoptions; ETHTOOL_A_HEADER_GFLAGS are global flags common
+for all request types, flags recognized in ETHTOOL_A_HEADER_RFLAGS and their
+interpretation are specific for each request type. Global flags are
+
+    ETHTOOL_RF_COMPACT		use compact format bitsets in reply
+    ETHTOOL_RF_REPLY		send optional reply (SET and ACT requests)
+
+Request specific flags are described with each request type. For both flag
+attributes, new flags should follow the general idea that if the flag is not
+set, the behaviour is the same as (or closer to) the behaviour before it was
+introduced.
+
+
+List of message types
+---------------------
+
+All constants identifying message types use ETHTOOL_CMD_ prefix and suffix
+according to message purpose:
+
+    _GET	userspace request to retrieve data
+    _SET	userspace request to set data
+    _ACT	userspace request to perform an action
+    _GET_REPLY	kernel reply to a GET request
+    _SET_REPLY	kernel reply to a SET request
+    _ACT_REPLY  kernel reply to an ACT request
+    _NTF	kernel notification
+
+"GET" requests are sent by userspace applications to retrieve device
+information. They usually do not contain any message specific attributes.
+Kernel replies with corresponding "GET_REPLY" message. For most types, "GET"
+request with NLM_F_DUMP and no device identification can be used to query the
+information for all devices supporting the request.
+
+If the data can be also modified, corresponding "SET" message with the same
+layout as "GET" reply is used to request changes. Only attributes where
+a change is requested are included in such request (also, not all attributes
+may be changed). Replies to most "SET" request consist only of error code and
+extack; if kernel provides additional data, it is sent in the form of
+corresponding "SET_REPLY" message (if ETHTOOL_RF_REPLY flag was set in request
+header).
+
+Data modification also triggers sending a "NTF" message with a notification.
+These usually bear only a subset of attributes which was affected by the
+change. The same notification is issued if the data is modified using other
+means (mostly ioctl ethtool interface). Unlike notifications from ethtool
+netlink code which are only sent if something actually changed, notifications
+triggered by ioctl interface may be sent even if the request did not actually
+change any data.
+
+"ACT" messages request kernel (driver) to perform a specific action. If some
+information is reported by kernel (as requested by ETHTOOL_RF_REPLY flag in
+request header), the reply takes form of an "ACT_REPLY" message. Performing an
+action also triggers a notification ("NTF" message).
+
+Later sections describe the format and semantics of these messages.
+
+
+Request translation
+-------------------
+
+The following table maps ioctl commands to netlink commands providing their
+functionality. Entries with "n/a" in right column are commands which do not
+have their netlink replacement yet.
+
+ioctl command			netlink command
+---------------------------------------------------------------------
+ETHTOOL_GSET			n/a
+ETHTOOL_SSET			n/a
+ETHTOOL_GDRVINFO		n/a
+ETHTOOL_GREGS			n/a
+ETHTOOL_GWOL			n/a
+ETHTOOL_SWOL			n/a
+ETHTOOL_GMSGLVL			n/a
+ETHTOOL_SMSGLVL			n/a
+ETHTOOL_NWAY_RST		n/a
+ETHTOOL_GLINK			n/a
+ETHTOOL_GEEPROM			n/a
+ETHTOOL_SEEPROM			n/a
+ETHTOOL_GCOALESCE		n/a
+ETHTOOL_SCOALESCE		n/a
+ETHTOOL_GRINGPARAM		n/a
+ETHTOOL_SRINGPARAM		n/a
+ETHTOOL_GPAUSEPARAM		n/a
+ETHTOOL_SPAUSEPARAM		n/a
+ETHTOOL_GRXCSUM			n/a
+ETHTOOL_SRXCSUM			n/a
+ETHTOOL_GTXCSUM			n/a
+ETHTOOL_STXCSUM			n/a
+ETHTOOL_GSG			n/a
+ETHTOOL_SSG			n/a
+ETHTOOL_TEST			n/a
+ETHTOOL_GSTRINGS		n/a
+ETHTOOL_PHYS_ID			n/a
+ETHTOOL_GSTATS			n/a
+ETHTOOL_GTSO			n/a
+ETHTOOL_STSO			n/a
+ETHTOOL_GPERMADDR		rtnetlink RTM_GETLINK
+ETHTOOL_GUFO			n/a
+ETHTOOL_SUFO			n/a
+ETHTOOL_GGSO			n/a
+ETHTOOL_SGSO			n/a
+ETHTOOL_GFLAGS			n/a
+ETHTOOL_SFLAGS			n/a
+ETHTOOL_GPFLAGS			n/a
+ETHTOOL_SPFLAGS			n/a
+ETHTOOL_GRXFH			n/a
+ETHTOOL_SRXFH			n/a
+ETHTOOL_GGRO			n/a
+ETHTOOL_SGRO			n/a
+ETHTOOL_GRXRINGS		n/a
+ETHTOOL_GRXCLSRLCNT		n/a
+ETHTOOL_GRXCLSRULE		n/a
+ETHTOOL_GRXCLSRLALL		n/a
+ETHTOOL_SRXCLSRLDEL		n/a
+ETHTOOL_SRXCLSRLINS		n/a
+ETHTOOL_FLASHDEV		n/a
+ETHTOOL_RESET			n/a
+ETHTOOL_SRXNTUPLE		n/a
+ETHTOOL_GRXNTUPLE		n/a
+ETHTOOL_GSSET_INFO		n/a
+ETHTOOL_GRXFHINDIR		n/a
+ETHTOOL_SRXFHINDIR		n/a
+ETHTOOL_GFEATURES		n/a
+ETHTOOL_SFEATURES		n/a
+ETHTOOL_GCHANNELS		n/a
+ETHTOOL_SCHANNELS		n/a
+ETHTOOL_SET_DUMP		n/a
+ETHTOOL_GET_DUMP_FLAG		n/a
+ETHTOOL_GET_DUMP_DATA		n/a
+ETHTOOL_GET_TS_INFO		n/a
+ETHTOOL_GMODULEINFO		n/a
+ETHTOOL_GMODULEEEPROM		n/a
+ETHTOOL_GEEE			n/a
+ETHTOOL_SEEE			n/a
+ETHTOOL_GRSSH			n/a
+ETHTOOL_SRSSH			n/a
+ETHTOOL_GTUNABLE		n/a
+ETHTOOL_STUNABLE		n/a
+ETHTOOL_GPHYSTATS		n/a
+ETHTOOL_PERQUEUE		n/a
+ETHTOOL_GLINKSETTINGS		n/a
+ETHTOOL_SLINKSETTINGS		n/a
+ETHTOOL_PHY_GTUNABLE		n/a
+ETHTOOL_PHY_STUNABLE		n/a
+ETHTOOL_GFECPARAM		n/a
+ETHTOOL_SFECPARAM		n/a
diff --git a/include/linux/ethtool_netlink.h b/include/linux/ethtool_netlink.h
new file mode 100644
index 000000000000..0412adb4f42f
--- /dev/null
+++ b/include/linux/ethtool_netlink.h
@@ -0,0 +1,9 @@
+/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
+
+#ifndef _LINUX_ETHTOOL_NETLINK_H_
+#define _LINUX_ETHTOOL_NETLINK_H_
+
+#include <uapi/linux/ethtool_netlink.h>
+#include <linux/ethtool.h>
+
+#endif /* _LINUX_ETHTOOL_NETLINK_H_ */
diff --git a/include/uapi/linux/ethtool_netlink.h b/include/uapi/linux/ethtool_netlink.h
new file mode 100644
index 000000000000..9a0fbd4f85d9
--- /dev/null
+++ b/include/uapi/linux/ethtool_netlink.h
@@ -0,0 +1,36 @@
+/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
+/*
+ * include/uapi/linux/ethtool_netlink.h - netlink interface for ethtool
+ *
+ * See Documentation/networking/ethtool-netlink.txt in kernel source tree for
+ * doucumentation of the interface.
+ */
+
+#ifndef _UAPI_LINUX_ETHTOOL_NETLINK_H_
+#define _UAPI_LINUX_ETHTOOL_NETLINK_H_
+
+#include <linux/ethtool.h>
+
+/* message types - userspace to kernel */
+enum {
+	ETHTOOL_MSG_USER_NONE,
+
+	/* add new constants above here */
+	__ETHTOOL_MSG_USER_CNT,
+	ETHTOOL_MSG_USER_MAX = (__ETHTOOL_MSG_USER_CNT - 1)
+};
+
+/* message types - kernel to userspace */
+enum {
+	ETHTOOL_MSG_KERNEL_NONE,
+
+	/* add new constants above here */
+	__ETHTOOL_MSG_KERNEL_CNT,
+	ETHTOOL_MSG_KERNEL_MAX = (__ETHTOOL_MSG_KERNEL_CNT - 1)
+};
+
+/* generic netlink info */
+#define ETHTOOL_GENL_NAME "ethtool"
+#define ETHTOOL_GENL_VERSION 1
+
+#endif /* _UAPI_LINUX_ETHTOOL_NETLINK_H_ */
diff --git a/net/Kconfig b/net/Kconfig
index 57f51a279ad6..65b760d26eec 100644
--- a/net/Kconfig
+++ b/net/Kconfig
@@ -447,6 +447,14 @@ config FAILOVER
 	  migration of VMs with direct attached VFs by failing over to the
 	  paravirtual datapath when the VF is unplugged.
 
+config ETHTOOL_NETLINK
+	bool "Netlink interface for ethtool"
+	default y
+	help
+	  An alternative userspace interface for ethtool based on generic
+	  netlink. It provides better extensibility and some new features,
+	  e.g. notification messages.
+
 endif   # if NET
 
 # Used by archs to tell that they support BPF JIT compiler plus which flavour.
diff --git a/net/ethtool/Makefile b/net/ethtool/Makefile
index 3ebfab2bca66..f30e0da88be5 100644
--- a/net/ethtool/Makefile
+++ b/net/ethtool/Makefile
@@ -1,3 +1,7 @@
 # SPDX-License-Identifier: GPL-2.0
 
-obj-y		+= ioctl.o
+obj-y				+= ioctl.o
+
+obj-$(CONFIG_ETHTOOL_NETLINK)	+= ethtool_nl.o
+
+ethtool_nl-y	:= netlink.o
diff --git a/net/ethtool/netlink.c b/net/ethtool/netlink.c
new file mode 100644
index 000000000000..3c98b41f04e5
--- /dev/null
+++ b/net/ethtool/netlink.c
@@ -0,0 +1,33 @@
+// SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note
+
+#include <linux/ethtool_netlink.h>
+#include "netlink.h"
+
+/* genetlink setup */
+
+static const struct genl_ops ethtool_genl_ops[] = {
+};
+
+static struct genl_family ethtool_genl_family = {
+	.name		= ETHTOOL_GENL_NAME,
+	.version	= ETHTOOL_GENL_VERSION,
+	.netnsok	= true,
+	.parallel_ops	= true,
+	.ops		= ethtool_genl_ops,
+	.n_ops		= ARRAY_SIZE(ethtool_genl_ops),
+};
+
+/* module setup */
+
+static int __init ethnl_init(void)
+{
+	int ret;
+
+	ret = genl_register_family(&ethtool_genl_family);
+	if (WARN(ret < 0, "ethtool: genetlink family registration failed"))
+		return ret;
+
+	return 0;
+}
+
+subsys_initcall(ethnl_init);
diff --git a/net/ethtool/netlink.h b/net/ethtool/netlink.h
new file mode 100644
index 000000000000..257ae55ccc82
--- /dev/null
+++ b/net/ethtool/netlink.h
@@ -0,0 +1,10 @@
+/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
+
+#ifndef _NET_ETHTOOL_NETLINK_H
+#define _NET_ETHTOOL_NETLINK_H
+
+#include <linux/ethtool_netlink.h>
+#include <linux/netdevice.h>
+#include <net/genetlink.h>
+
+#endif /* _NET_ETHTOOL_NETLINK_H */
-- 
2.22.0