nl80211: vendor command support

Add support for vendor-specific commands to nl80211. This is
intended to be used for really vendor-specific functionality
that can't be implemented in a generic fashion for any reason.
It's *NOT* intended to be used for any normal/generic feature
or any optimisations that could be implemented across drivers.

Currently, only vendor commands (with replies) are supported,
no dump operations or vendor-specific notifications.

Also add a function wdev_to_ieee80211_vif() to mac80211 which
is needed for mac80211-based drivers wanting to implement any
vendor commands.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>

3 files changed, 167 insertions, 3 deletions

diff --git a/include/net/cfg80211.h b/include/net/cfg80211.h
index 47290a4059a..884ac69b5e5 100644
--- a/include/net/cfg80211.h
+++ b/include/net/cfg80211.h
@@ -2680,6 +2680,34 @@ struct wiphy_coalesce_support {
 };
 
 /**
+ * enum wiphy_vendor_command_flags - validation flags for vendor commands
+ * @WIPHY_VENDOR_CMD_NEED_WDEV: vendor command requires wdev
+ * @WIPHY_VENDOR_CMD_NEED_NETDEV: vendor command requires netdev
+ * @WIPHY_VENDOR_CMD_NEED_RUNNING: interface/wdev must be up & running
+ *	(must be combined with %_WDEV or %_NETDEV)
+ */
+enum wiphy_vendor_command_flags {
+	WIPHY_VENDOR_CMD_NEED_WDEV = BIT(0),
+	WIPHY_VENDOR_CMD_NEED_NETDEV = BIT(1),
+	WIPHY_VENDOR_CMD_NEED_RUNNING = BIT(2),
+};
+
+/**
+ * struct wiphy_vendor_command - vendor command definition
+ * @info: vendor command identifying information, as used in nl80211
+ * @flags: flags, see &enum wiphy_vendor_command_flags
+ * @doit: callback for the operation, note that wdev is %NULL if the
+ *	flags didn't ask for a wdev and non-%NULL otherwise; the data
+ *	pointer may be %NULL if userspace provided no data at all
+ */
+struct wiphy_vendor_command {
+	struct nl80211_vendor_cmd_info info;
+	u32 flags;
+	int (*doit)(struct wiphy *wiphy, struct wireless_dev *wdev,
+		    const void *data, int data_len);
+};
+
+/**
  * struct wiphy - wireless hardware description
  * @reg_notifier: the driver's regulatory notification callback,
  *	note that if your driver uses wiphy_apply_custom_regulatory()
@@ -2792,6 +2820,9 @@ struct wiphy_coalesce_support {
  * @extended_capabilities_mask: mask of the valid values
  * @extended_capabilities_len: length of the extended capabilities
  * @coalesce: packet coalescing support information
+ *
+ * @vendor_commands: array of vendor commands supported by the hardware
+ * @n_vendor_commands: number of vendor commands
  */
 struct wiphy {
 	/* assign these fields before you register the wiphy */
@@ -2903,6 +2934,9 @@ struct wiphy {
 
 	const struct wiphy_coalesce_support *coalesce;
 
+	const struct wiphy_vendor_command *vendor_commands;
+	int n_vendor_commands;
+
 	char priv[0] __aligned(NETDEV_ALIGN);
 };
 
@@ -3847,6 +3881,75 @@ void wiphy_rfkill_start_polling(struct wiphy *wiphy);
  */
 void wiphy_rfkill_stop_polling(struct wiphy *wiphy);
 
+/**
+ * DOC: Vendor commands
+ *
+ * Occasionally, there are special protocol or firmware features that
+ * can't be implemented very openly. For this and similar cases, the
+ * vendor command functionality allows implementing the features with
+ * (typically closed-source) userspace and firmware, using nl80211 as
+ * the configuration mechanism.
+ *
+ * A driver supporting vendor commands must register them as an array
+ * in struct wiphy, with handlers for each one, each command has an
+ * OUI and sub command ID to identify it.
+ *
+ * Note that this feature should not be (ab)used to implement protocol
+ * features that could openly be shared across drivers. In particular,
+ * it must never be required to use vendor commands to implement any
+ * "normal" functionality that higher-level userspace like connection
+ * managers etc. need.
+ */
+
+struct sk_buff *__cfg80211_alloc_reply_skb(struct wiphy *wiphy,
+					   enum nl80211_commands cmd,
+					   enum nl80211_attrs attr,
+					   int approxlen);
+
+/**
+ * cfg80211_vendor_cmd_alloc_reply_skb - allocate vendor command reply
+ * @wiphy: the wiphy
+ * @approxlen: an upper bound of the length of the data that will
+ *	be put into the skb
+ *
+ * This function allocates and pre-fills an skb for a reply to
+ * a vendor command. Since it is intended for a reply, calling
+ * it outside of a vendor command's doit() operation is invalid.
+ *
+ * The returned skb is pre-filled with some identifying data in
+ * a way that any data that is put into the skb (with skb_put(),
+ * nla_put() or similar) will end up being within the
+ * %NL80211_ATTR_VENDOR_DATA attribute, so all that needs to be done
+ * with the skb is adding data for the corresponding userspace tool
+ * which can then read that data out of the vendor data attribute.
+ * You must not modify the skb in any other way.
+ *
+ * When done, call cfg80211_vendor_cmd_reply() with the skb and return
+ * its error code as the result of the doit() operation.
+ *
+ * Return: An allocated and pre-filled skb. %NULL if any errors happen.
+ */
+static inline struct sk_buff *
+cfg80211_vendor_cmd_alloc_reply_skb(struct wiphy *wiphy, int approxlen)
+{
+	return __cfg80211_alloc_reply_skb(wiphy, NL80211_CMD_VENDOR,
+					  NL80211_ATTR_VENDOR_DATA, approxlen);
+}
+
+/**
+ * cfg80211_vendor_cmd_reply - send the reply skb
+ * @skb: The skb, must have been allocated with
+ *	cfg80211_vendor_cmd_alloc_reply_skb()
+ *
+ * Since calling this function will usually be the last thing
+ * before returning from the vendor command doit() you should
+ * return the error code.  Note that this function consumes the
+ * skb regardless of the return value.
+ *
+ * Return: An error code or 0 on success.
+ */
+int cfg80211_vendor_cmd_reply(struct sk_buff *skb);
+
 #ifdef CONFIG_NL80211_TESTMODE
 /**
  * DOC: Test mode
@@ -3882,8 +3985,12 @@ void wiphy_rfkill_stop_polling(struct wiphy *wiphy);
  *
  * Return: An allocated and pre-filled skb. %NULL if any errors happen.
  */
-struct sk_buff *cfg80211_testmode_alloc_reply_skb(struct wiphy *wiphy,
-						  int approxlen);
+static inline struct sk_buff *
+cfg80211_testmode_alloc_reply_skb(struct wiphy *wiphy, int approxlen)
+{
+	return __cfg80211_alloc_reply_skb(wiphy, NL80211_CMD_TESTMODE,
+					  NL80211_ATTR_TESTDATA, approxlen);
+}
 
 /**
  * cfg80211_testmode_reply - send the reply skb
@@ -3897,7 +4004,10 @@ struct sk_buff *cfg80211_testmode_alloc_reply_skb(struct wiphy *wiphy,
  *
  * Return: An error code or 0 on success.
  */
-int cfg80211_testmode_reply(struct sk_buff *skb);
+static inline int cfg80211_testmode_reply(struct sk_buff *skb)
+{
+	return cfg80211_vendor_cmd_reply(skb);
+}
 
 /**
  * cfg80211_testmode_alloc_event_skb - allocate testmode event
diff --git a/include/net/mac80211.h b/include/net/mac80211.h
index 73d99bc3e63..c014acc09eb 100644
--- a/include/net/mac80211.h
+++ b/include/net/mac80211.h
@@ -1163,6 +1163,19 @@ static inline bool ieee80211_vif_is_mesh(struct ieee80211_vif *vif)
 }
 
 /**
+ * wdev_to_ieee80211_vif - return a vif struct from a wdev
+ * @wdev: the wdev to get the vif for
+ *
+ * This can be used by mac80211 drivers with direct cfg80211 APIs
+ * (like the vendor commands) that get a wdev.
+ *
+ * Note that this function may return %NULL if the given wdev isn't
+ * associated with a vif that the driver knows about (e.g. monitor
+ * or AP_VLAN interfaces.)
+ */
+struct ieee80211_vif *wdev_to_ieee80211_vif(struct wireless_dev *wdev);
+
+/**
  * enum ieee80211_key_flags - key flags
  *
  * These flags are used for communication about keys between the driver
diff --git a/include/uapi/linux/nl80211.h b/include/uapi/linux/nl80211.h
index 9a4d0e18251..72ba3584c90 100644
--- a/include/uapi/linux/nl80211.h
+++ b/include/uapi/linux/nl80211.h
@@ -693,6 +693,15 @@
  *	other station that transmission must be blocked until the channel
  *	switch is complete.
  *
+ * @NL80211_CMD_VENDOR: Vendor-specified command/event. The command is specified
+ *	by the %NL80211_ATTR_VENDOR_ID attribute and a sub-command in
+ *	%NL80211_ATTR_VENDOR_SUBCMD. Parameter(s) can be transported in
+ *	%NL80211_ATTR_VENDOR_DATA.
+ *	For feature advertisement, the %NL80211_ATTR_VENDOR_DATA attribute is
+ *	used in the wiphy data as a nested attribute containing descriptions
+ *	(&struct nl80211_vendor_cmd_info) of the supported vendor commands.
+ *	This may also be sent as an event with the same attributes.
+ *
  * @NL80211_CMD_MAX: highest used command number
  * @__NL80211_CMD_AFTER_LAST: internal use
  */
@@ -860,6 +869,8 @@ enum nl80211_commands {
 
 	NL80211_CMD_CHANNEL_SWITCH,
 
+	NL80211_CMD_VENDOR,
+
 	/* add new commands above here */
 
 	/* used to define NL80211_CMD_MAX below */
@@ -1524,6 +1535,12 @@ enum nl80211_commands {
  *	Notification Element based on association request when used with
  *	%NL80211_CMD_NEW_STATION; u8 attribute.
  *
+ * @NL80211_ATTR_VENDOR_ID: The vendor ID, either a 24-bit OUI or, if
+ *	%NL80211_VENDOR_ID_IS_LINUX is set, a special Linux ID (not used yet)
+ * @NL80211_ATTR_VENDOR_SUBCMD: vendor sub-command
+ * @NL80211_ATTR_VENDOR_DATA: data for the vendor command, if any; this
+ *	attribute is also used for vendor command feature advertisement
+ *
  * @NL80211_ATTR_MAX: highest attribute number currently defined
  * @__NL80211_ATTR_AFTER_LAST: internal use
  */
@@ -1845,6 +1862,10 @@ enum nl80211_attrs {
 
 	NL80211_ATTR_OPMODE_NOTIF,
 
+	NL80211_ATTR_VENDOR_ID,
+	NL80211_ATTR_VENDOR_SUBCMD,
+	NL80211_ATTR_VENDOR_DATA,
+
 	/* add attributes here, update the policy in nl80211.c */
 
 	__NL80211_ATTR_AFTER_LAST,
@@ -3965,4 +3986,24 @@ enum nl80211_rxmgmt_flags {
 	NL80211_RXMGMT_FLAG_ANSWERED = 1 << 0,
 };
 
+/*
+ * If this flag is unset, the lower 24 bits are an OUI, if set
+ * a Linux nl80211 vendor ID is used (no such IDs are allocated
+ * yet, so that's not valid so far)
+ */
+#define NL80211_VENDOR_ID_IS_LINUX	0x80000000
+
+/**
+ * struct nl80211_vendor_cmd_info - vendor command data
+ * @vendor_id: If the %NL80211_VENDOR_ID_IS_LINUX flag is clear, then the
+ *	value is a 24-bit OUI; if it is set then a separately allocated ID
+ *	may be used, but no such IDs are allocated yet. New IDs should be
+ *	added to this file when needed.
+ * @subcmd: sub-command ID for the command
+ */
+struct nl80211_vendor_cmd_info {
+	__u32 vendor_id;
+	__u32 subcmd;
+};
+
 #endif /* __LINUX_NL80211_H */