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

From: Michal Kubecek
Date: Tue Jul 02 2019 - 07:50:06 EST

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@xxxxxxx>
---
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