Implement LINKMODES_GET netlink request to get link modes related
information provided by ETHTOOL_GLINKSETTINGS and ETHTOOL_GSET ioctl
commands.

This request provides supported, advertised and peer advertised link modes,
autonegotiation flag, speed and duplex.

LINKMODES_GET request can be used with NLM_F_DUMP (without device
identification) to request the information for all devices in current
network namespace providing the data.

Signed-off-by: Michal Kubecek <mkube...@suse.cz>
---
 Documentation/networking/ethtool-netlink.rst |  37 +++++
 include/linux/ethtool_netlink.h              |   3 +
 include/uapi/linux/ethtool_netlink.h         |  20 +++
 net/ethtool/Makefile                         |   2 +-
 net/ethtool/linkmodes.c                      | 163 +++++++++++++++++++
 net/ethtool/netlink.c                        |   8 +
 net/ethtool/netlink.h                        |   1 +
 7 files changed, 233 insertions(+), 1 deletion(-)
 create mode 100644 net/ethtool/linkmodes.c

diff --git a/Documentation/networking/ethtool-netlink.rst 
b/Documentation/networking/ethtool-netlink.rst
index 48833b6092d9..e04c90ee526e 100644
--- a/Documentation/networking/ethtool-netlink.rst
+++ b/Documentation/networking/ethtool-netlink.rst
@@ -169,6 +169,7 @@ Userspace to kernel:
   ``ETHTOOL_MSG_STRSET_GET``            get string set
   ``ETHTOOL_MSG_LINKINFO_GET``          get link settings
   ``ETHTOOL_MSG_LINKINFO_SET``          set link settings
+  ``ETHTOOL_MSG_LINKMODES_GET``         get link modes info
   ===================================== ================================
 
 Kernel to userspace:
@@ -177,6 +178,7 @@ Kernel to userspace:
   ``ETHTOOL_MSG_STRSET_GET_REPLY``      string set contents
   ``ETHTOOL_MSG_LINKINFO_GET_REPLY``    link settings
   ``ETHTOOL_MSG_LINKINFO_NTF``          link settings notification
+  ``ETHTOOL_MSG_LINKMODES_GET_REPLY``   link modes info
   ===================================== ================================
 
 ``GET`` requests are sent by userspace applications to retrieve device
@@ -321,6 +323,39 @@ MDI(-X) status and transceiver cannot be set, request with 
the corresponding
 attributes is rejected.
 
 
+LINKMODES_GET
+=============
+
+Requests link modes (supported, advertised and peer advertised) and related
+information (autonegotiation status, link speed and duplex) as provided by
+``ETHTOOL_GLINKSETTINGS``. The request does not use any attributes and does
+not have any request specific flags.
+
+Request contents:
+
+  ====================================  ======  ==========================
+  ``ETHTOOL_A_LINKMODES_HEADER``        nested  request header
+  ====================================  ======  ==========================
+
+Kernel response contents:
+
+  ====================================  ======  ==========================
+  ``ETHTOOL_A_LINKMODES_HEADER``        nested  reply header
+  ``ETHTOOL_A_LINKMODES_AUTONEG``       u8      autonegotiation status
+  ``ETHTOOL_A_LINKMODES_OURS``          bitset  advertised link modes
+  ``ETHTOOL_A_LINKMODES_PEER``          bitset  partner link modes
+  ``ETHTOOL_A_LINKMODES_SPEED``         u32     link speed (Mb/s)
+  ``ETHTOOL_A_LINKMODES_DUPLEX``        u8      duplex mode
+  ====================================  ======  ==========================
+
+For ``ETHTOOL_A_LINKMODES_OURS``, value represents advertised modes and mask
+represents supported modes. ``ETHTOOL_A_LINKMODES_PEER`` in the reply is a bit
+list.
+
+``LINKMODES_GET`` allows dump requests (kernel returns reply messages for all
+devices supporting the request).
+
+
 Request translation
 ===================
 
@@ -332,6 +367,7 @@ have their netlink replacement yet.
   ioctl command                       netlink command
   =================================== =====================================
   ``ETHTOOL_GSET``                    ``ETHTOOL_MSG_LINKINFO_GET``
+                                      ``ETHTOOL_MSG_LINKMODES_GET``
   ``ETHTOOL_SSET``                    ``ETHTOOL_MSG_LINKINFO_SET``
   ``ETHTOOL_GDRVINFO``                n/a
   ``ETHTOOL_GREGS``                   n/a
@@ -406,6 +442,7 @@ have their netlink replacement yet.
   ``ETHTOOL_GPHYSTATS``               n/a
   ``ETHTOOL_PERQUEUE``                n/a
   ``ETHTOOL_GLINKSETTINGS``           ``ETHTOOL_MSG_LINKINFO_GET``
+                                      ``ETHTOOL_MSG_LINKMODES_GET``
   ``ETHTOOL_SLINKSETTINGS``           ``ETHTOOL_MSG_LINKINFO_SET``
   ``ETHTOOL_PHY_GTUNABLE``            n/a
   ``ETHTOOL_PHY_STUNABLE``            n/a
diff --git a/include/linux/ethtool_netlink.h b/include/linux/ethtool_netlink.h
index 2a15e64a16f3..e770e6e9acca 100644
--- a/include/linux/ethtool_netlink.h
+++ b/include/linux/ethtool_netlink.h
@@ -7,6 +7,9 @@
 #include <linux/ethtool.h>
 #include <linux/netdevice.h>
 
+#define __ETHTOOL_LINK_MODE_MASK_NWORDS \
+       DIV_ROUND_UP(__ETHTOOL_LINK_MODE_MASK_NBITS, 32)
+
 enum ethtool_multicast_groups {
        ETHNL_MCGRP_MONITOR,
 };
diff --git a/include/uapi/linux/ethtool_netlink.h 
b/include/uapi/linux/ethtool_netlink.h
index 78ee5584d5da..d8ec49aebe48 100644
--- a/include/uapi/linux/ethtool_netlink.h
+++ b/include/uapi/linux/ethtool_netlink.h
@@ -17,6 +17,7 @@ enum {
        ETHTOOL_MSG_STRSET_GET,
        ETHTOOL_MSG_LINKINFO_GET,
        ETHTOOL_MSG_LINKINFO_SET,
+       ETHTOOL_MSG_LINKMODES_GET,
 
        /* add new constants above here */
        __ETHTOOL_MSG_USER_CNT,
@@ -29,6 +30,7 @@ enum {
        ETHTOOL_MSG_STRSET_GET_REPLY,
        ETHTOOL_MSG_LINKINFO_GET_REPLY,
        ETHTOOL_MSG_LINKINFO_NTF,
+       ETHTOOL_MSG_LINKMODES_GET_REPLY,
 
        /* add new constants above here */
        __ETHTOOL_MSG_KERNEL_CNT,
@@ -168,6 +170,24 @@ enum {
 
 #define ETHTOOL_RFLAG_LINKINFO_ALL 0
 
+/* LINKMODES */
+
+enum {
+       ETHTOOL_A_LINKMODES_UNSPEC,
+       ETHTOOL_A_LINKMODES_HEADER,             /* nest - _A_HEADER_* */
+       ETHTOOL_A_LINKMODES_AUTONEG,            /* u8 */
+       ETHTOOL_A_LINKMODES_OURS,               /* bitset */
+       ETHTOOL_A_LINKMODES_PEER,               /* bitset */
+       ETHTOOL_A_LINKMODES_SPEED,              /* u32 */
+       ETHTOOL_A_LINKMODES_DUPLEX,             /* u8 */
+
+       /* add new constants above here */
+       __ETHTOOL_A_LINKMODES_CNT,
+       ETHTOOL_A_LINKMODES_MAX = __ETHTOOL_A_LINKMODES_CNT - 1
+};
+
+#define ETHTOOL_RFLAG_LINKMODES_ALL 0
+
 /* generic netlink info */
 #define ETHTOOL_GENL_NAME "ethtool"
 #define ETHTOOL_GENL_VERSION 1
diff --git a/net/ethtool/Makefile b/net/ethtool/Makefile
index 28666a0eede8..9ae0786c343b 100644
--- a/net/ethtool/Makefile
+++ b/net/ethtool/Makefile
@@ -4,4 +4,4 @@ obj-y                           += ioctl.o common.o
 
 obj-$(CONFIG_ETHTOOL_NETLINK)  += ethtool_nl.o
 
-ethtool_nl-y   := netlink.o bitset.o strset.o linkinfo.o
+ethtool_nl-y   := netlink.o bitset.o strset.o linkinfo.o linkmodes.o
diff --git a/net/ethtool/linkmodes.c b/net/ethtool/linkmodes.c
new file mode 100644
index 000000000000..3441f29b8e67
--- /dev/null
+++ b/net/ethtool/linkmodes.c
@@ -0,0 +1,163 @@
+// SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note
+
+#include "netlink.h"
+#include "common.h"
+#include "bitset.h"
+
+struct linkmodes_req_info {
+       struct ethnl_req_info           base;
+};
+
+struct linkmodes_reply_data {
+       struct ethnl_reply_data         base;
+       struct ethtool_link_ksettings   ksettings;
+       struct ethtool_link_settings    *lsettings;
+       bool                            peer_empty;
+};
+
+static const struct nla_policy
+linkmodes_get_policy[ETHTOOL_A_LINKMODES_MAX + 1] = {
+       [ETHTOOL_A_LINKMODES_UNSPEC]            = { .type = NLA_REJECT },
+       [ETHTOOL_A_LINKMODES_HEADER]            = { .type = NLA_NESTED },
+       [ETHTOOL_A_LINKMODES_AUTONEG]           = { .type = NLA_REJECT },
+       [ETHTOOL_A_LINKMODES_OURS]              = { .type = NLA_REJECT },
+       [ETHTOOL_A_LINKMODES_PEER]              = { .type = NLA_REJECT },
+       [ETHTOOL_A_LINKMODES_SPEED]             = { .type = NLA_REJECT },
+       [ETHTOOL_A_LINKMODES_DUPLEX]            = { .type = NLA_REJECT },
+};
+
+/* prepare_data() handler */
+static int linkmodes_prepare(const struct ethnl_req_info *req_base,
+                            struct ethnl_reply_data *reply_base,
+                            struct genl_info *info)
+{
+       struct linkmodes_reply_data *data =
+               container_of(reply_base, struct linkmodes_reply_data, base);
+       struct net_device *dev = reply_base->dev;
+       int ret;
+
+       data->lsettings = &data->ksettings.base;
+
+       ret = ethnl_before_ops(dev);
+       if (ret < 0)
+               return ret;
+
+       ret = __ethtool_get_link_ksettings(dev, &data->ksettings);
+       if (ret < 0 && info) {
+               GENL_SET_ERR_MSG(info, "failed to retrieve link settings");
+               goto out;
+       }
+
+       data->peer_empty =
+               bitmap_empty(data->ksettings.link_modes.lp_advertising,
+                            __ETHTOOL_LINK_MODE_MASK_NBITS);
+       ethnl_bitmap_to_u32(data->ksettings.link_modes.supported,
+                           __ETHTOOL_LINK_MODE_MASK_NWORDS);
+       ethnl_bitmap_to_u32(data->ksettings.link_modes.advertising,
+                           __ETHTOOL_LINK_MODE_MASK_NWORDS);
+       ethnl_bitmap_to_u32(data->ksettings.link_modes.lp_advertising,
+                           __ETHTOOL_LINK_MODE_MASK_NWORDS);
+
+out:
+       ethnl_after_ops(dev);
+       return ret;
+}
+
+/* reply_size() handler */
+static int linkmodes_size(const struct ethnl_req_info *req_base,
+                         const struct ethnl_reply_data *reply_base)
+{
+       const struct linkmodes_reply_data *data =
+               container_of(reply_base, struct linkmodes_reply_data, base);
+       const struct ethtool_link_ksettings *ksettings = &data->ksettings;
+       const u32 *advertising;
+       const u32 *supported;
+       const u32 *lp_adv;
+       bool compact;
+       int len, ret;
+
+       supported = (const u32 *)ksettings->link_modes.supported;
+       advertising = (const u32 *)ksettings->link_modes.advertising;
+       lp_adv = (const u32 *)ksettings->link_modes.lp_advertising;
+       compact = req_base->global_flags & ETHTOOL_GFLAG_COMPACT_BITSETS;
+
+       len = nla_total_size(sizeof(u8)) /* LINKMODES_AUTONEG */
+               + nla_total_size(sizeof(u32)) /* LINKMODES_SPEED */
+               + nla_total_size(sizeof(u8)) /* LINKMODES_DUPLEX */
+               + 0;
+       ret = ethnl_bitset32_size(advertising, supported,
+                                 __ETHTOOL_LINK_MODE_MASK_NBITS,
+                                 link_mode_names, compact);
+       if (ret < 0)
+               return ret;
+       len += ret;
+       if (!data->peer_empty) {
+               ret = ethnl_bitset32_size(lp_adv, NULL,
+                                         __ETHTOOL_LINK_MODE_MASK_NBITS,
+                                         link_mode_names, compact);
+               if (ret < 0)
+                       return ret;
+               len += ret;
+       }
+
+       return len;
+}
+
+/* fill_reply() handler */
+static int linkmodes_fill(struct sk_buff *skb,
+                         const struct ethnl_req_info *req_base,
+                         const struct ethnl_reply_data *reply_base)
+{
+       const struct linkmodes_reply_data *data =
+               container_of(reply_base, struct linkmodes_reply_data, base);
+       const struct ethtool_link_ksettings *ksettings = &data->ksettings;
+       const struct ethtool_link_settings *lsettings = &ksettings->base;
+       const u32 *advertising;
+       const u32 *supported;
+       const u32 *lp_adv;
+       bool compact;
+       int ret;
+
+       supported = (const u32 *)ksettings->link_modes.supported;
+       advertising = (const u32 *)ksettings->link_modes.advertising;
+       lp_adv = (const u32 *)ksettings->link_modes.lp_advertising;
+       compact = req_base->global_flags & ETHTOOL_GFLAG_COMPACT_BITSETS;
+
+       if (nla_put_u8(skb, ETHTOOL_A_LINKMODES_AUTONEG, lsettings->autoneg))
+               return -EMSGSIZE;
+
+       ret = ethnl_put_bitset32(skb, ETHTOOL_A_LINKMODES_OURS, advertising,
+                                supported, __ETHTOOL_LINK_MODE_MASK_NBITS,
+                                link_mode_names, compact);
+       if (ret < 0)
+               return -EMSGSIZE;
+       if (!data->peer_empty) {
+               ret = ethnl_put_bitset32(skb, ETHTOOL_A_LINKMODES_PEER,
+                                        lp_adv, NULL,
+                                        __ETHTOOL_LINK_MODE_MASK_NBITS,
+                                        link_mode_names, compact);
+               if (ret < 0)
+                       return -EMSGSIZE;
+       }
+
+       if (nla_put_u32(skb, ETHTOOL_A_LINKMODES_SPEED, lsettings->speed) ||
+           nla_put_u8(skb, ETHTOOL_A_LINKMODES_DUPLEX, lsettings->duplex))
+               return -EMSGSIZE;
+
+       return 0;
+}
+
+const struct get_request_ops linkmodes_request_ops = {
+       .request_cmd            = ETHTOOL_MSG_LINKMODES_GET,
+       .reply_cmd              = ETHTOOL_MSG_LINKMODES_GET_REPLY,
+       .hdr_attr               = ETHTOOL_A_LINKMODES_HEADER,
+       .max_attr               = ETHTOOL_A_LINKMODES_MAX,
+       .req_info_size          = sizeof(struct linkmodes_req_info),
+       .reply_data_size        = sizeof(struct linkmodes_reply_data),
+       .request_policy         = linkmodes_get_policy,
+       .all_reqflags           = ETHTOOL_RFLAG_LINKMODES_ALL,
+
+       .prepare_data           = linkmodes_prepare,
+       .reply_size             = linkmodes_size,
+       .fill_reply             = linkmodes_fill,
+};
diff --git a/net/ethtool/netlink.c b/net/ethtool/netlink.c
index 5b9d12656e97..73d990b4d5c1 100644
--- a/net/ethtool/netlink.c
+++ b/net/ethtool/netlink.c
@@ -294,6 +294,7 @@ struct ethnl_dump_ctx {
 static const struct get_request_ops *get_requests[__ETHTOOL_MSG_USER_CNT] = {
        [ETHTOOL_MSG_STRSET_GET]        = &strset_request_ops,
        [ETHTOOL_MSG_LINKINFO_GET]      = &linkinfo_request_ops,
+       [ETHTOOL_MSG_LINKMODES_GET]     = &linkmodes_request_ops,
 };
 
 static struct ethnl_dump_ctx *ethnl_dump_context(struct netlink_callback *cb)
@@ -728,6 +729,13 @@ static const struct genl_ops ethtool_genl_ops[] = {
                .flags  = GENL_UNS_ADMIN_PERM,
                .doit   = ethnl_set_linkinfo,
        },
+       {
+               .cmd    = ETHTOOL_MSG_LINKMODES_GET,
+               .doit   = ethnl_get_doit,
+               .start  = ethnl_get_start,
+               .dumpit = ethnl_get_dumpit,
+               .done   = ethnl_get_done,
+       },
 };
 
 static const struct genl_multicast_group ethtool_nl_mcgrps[] = {
diff --git a/net/ethtool/netlink.h b/net/ethtool/netlink.h
index ca136dd7ea02..b330b29fe927 100644
--- a/net/ethtool/netlink.h
+++ b/net/ethtool/netlink.h
@@ -349,6 +349,7 @@ struct get_request_ops {
 
 extern const struct get_request_ops strset_request_ops;
 extern const struct get_request_ops linkinfo_request_ops;
+extern const struct get_request_ops linkmodes_request_ops;
 
 int ethnl_set_linkinfo(struct sk_buff *skb, struct genl_info *info);
 
-- 
2.23.0

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