[PATCH net-next v7 04/17] ethtool: introduce ethtool netlink interface

From: Michal Kubecek
Date: Wed Oct 09 2019 - 16:59:19 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.rst, further patches will add more
detailed information.

Signed-off-by: Michal Kubecek <mkubecek@xxxxxxx>
---
Documentation/networking/ethtool-netlink.rst | 219 +++++++++++++++++++
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, 320 insertions(+), 1 deletion(-)
create mode 100644 Documentation/networking/ethtool-netlink.rst
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.rst b/Documentation/networking/ethtool-netlink.rst
new file mode 100644
index 000000000000..3e9680b63afa
--- /dev/null
+++ b/Documentation/networking/ethtool-netlink.rst
@@ -0,0 +1,219 @@
+=============================
+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_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).
+
+The two flag bitmaps are used for request options; ``ETHTOOL_A_HEADER_GFLAGS``
+holds global flags common for all request types. Recognized flags are:
+
+ ================================= ===================================
+ ``ETHTOOL_GFLAG_COMPACT_BITSETS`` use compact format bitsets in reply
+ ``ETHTOOL_GFLAG_OMIT_REPLY`` omit optional reply (_SET and _ACT)
+ ================================= ===================================
+
+Flags in ``ETHTOOL_A_HEADER_GFLAGS`` and their interpretation are specific for
+each request. They are listed and explained in further sections describing
+those request types.
+
+For both flag attributes, new flags should follow the general idea that if the
+flag is not set, the behaviour is backward compatible, i.e. requests from old
+clients not aware of the flag should be interpreted the way the client
+expects. A client must not set flags it does not understand.
+
+
+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 corresponding ``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 which can be suppressed by
+setting ``ETHTOOL_GFLAG_OMIT_REPLY`` flag 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 (which can be suppressed by setting
+``ETHTOOL_GFLAG_OMIT_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..468f5b00edcc
--- /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 3101bfcbdd7a..f6886b9d3c1c 100644
--- a/net/Kconfig
+++ b/net/Kconfig
@@ -448,6 +448,14 @@ 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 */
--
2.23.0