wifi: cfg80211: do some rework towards MLO link APIs

In order to support multi-link operation with multiple links,
start adding some APIs. The notable addition here is to have
the link ID in a new nl80211 attribute, that will be used to
differentiate the links in many nl80211 operations.

So far, this patch adds the netlink NL80211_ATTR_MLO_LINK_ID
attribute (as well as the NL80211_ATTR_MLO_LINKS attribute)
and plugs it through the system in some places, checking the
validity etc. along with other infrastructure needed for it.

For now, I've decided to include only the over-the-air link
ID in the API. I know we discussed that we eventually need to
have to have other ways of identifying a link, but for local
AP mode and auth/assoc commands as well as set_key etc. we'll
use the OTA ID.

Also included in this patch is some refactoring of the data
structures in struct wireless_dev, splitting for the first
time the data into type dependent pieces, to make reasoning
about these things easier.

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

3 files changed, 120 insertions, 10 deletions

diff --git a/include/linux/ieee80211.h b/include/linux/ieee80211.h
index 5c65ae6b8154..e15771965916 100644
--- a/include/linux/ieee80211.h
+++ b/include/linux/ieee80211.h
@@ -4376,4 +4376,7 @@ enum ieee80211_range_params_max_total_ltf {
 	IEEE80211_RANGE_PARAMS_MAX_TOTAL_LTF_UNSPECIFIED,
 };
 
+/* multi-link device */
+#define IEEE80211_MLD_MAX_NUM_LINKS	15
+
 #endif /* LINUX_IEEE80211_H */
diff --git a/include/net/cfg80211.h b/include/net/cfg80211.h
index 6d02e12e4702..772e099fc932 100644
--- a/include/net/cfg80211.h
+++ b/include/net/cfg80211.h
@@ -1158,6 +1158,7 @@ struct cfg80211_mbssid_elems {
 
 /**
  * struct cfg80211_beacon_data - beacon data
+ * @link_id: the link ID for the AP MLD link sending this beacon
  * @head: head portion of beacon (before TIM IE)
  *	or %NULL if not changed
  * @tail: tail portion of beacon (after TIM IE)
@@ -1188,6 +1189,8 @@ struct cfg80211_mbssid_elems {
  *	attribute is present in beacon data or not.
  */
 struct cfg80211_beacon_data {
+	unsigned int link_id;
+
 	const u8 *head, *tail;
 	const u8 *beacon_ies;
 	const u8 *proberesp_ies;
@@ -4201,7 +4204,8 @@ struct cfg80211_ops {
 			    struct cfg80211_ap_settings *settings);
 	int	(*change_beacon)(struct wiphy *wiphy, struct net_device *dev,
 				 struct cfg80211_beacon_data *info);
-	int	(*stop_ap)(struct wiphy *wiphy, struct net_device *dev);
+	int	(*stop_ap)(struct wiphy *wiphy, struct net_device *dev,
+			   unsigned int link_id);
 
 
 	int	(*add_station)(struct wiphy *wiphy, struct net_device *dev,
@@ -4309,6 +4313,7 @@ struct cfg80211_ops {
 
 	int	(*set_bitrate_mask)(struct wiphy *wiphy,
 				    struct net_device *dev,
+				    unsigned int link_id,
 				    const u8 *peer,
 				    const struct cfg80211_bitrate_mask *mask);
 
@@ -4384,6 +4389,7 @@ struct cfg80211_ops {
 
 	int	(*get_channel)(struct wiphy *wiphy,
 			       struct wireless_dev *wdev,
+			       unsigned int link_id,
 			       struct cfg80211_chan_def *chandef);
 
 	int	(*start_p2p_device)(struct wiphy *wiphy,
@@ -4420,6 +4426,7 @@ struct cfg80211_ops {
 			       struct cfg80211_qos_map *qos_map);
 
 	int	(*set_ap_chanwidth)(struct wiphy *wiphy, struct net_device *dev,
+				    unsigned int link_id,
 				    struct cfg80211_chan_def *chandef);
 
 	int	(*add_tx_ts)(struct wiphy *wiphy, struct net_device *dev,
@@ -4545,10 +4552,14 @@ struct cfg80211_ops {
  * @WIPHY_FLAG_HAS_STATIC_WEP: The device supports static WEP key installation
  *	before connection.
  * @WIPHY_FLAG_SUPPORTS_EXT_KEK_KCK: The device supports bigger kek and kck keys
+ * @WIPHY_FLAG_SUPPORTS_MLO: This is a temporary flag gating the MLO APIs,
+ *	in order to not have them reachable in normal drivers, until we have
+ *	complete feature/interface combinations/etc. advertisement. No driver
+ *	should set this flag for now.
  */
 enum wiphy_flags {
 	WIPHY_FLAG_SUPPORTS_EXT_KEK_KCK		= BIT(0),
-	/* use hole at 1 */
+	WIPHY_FLAG_SUPPORTS_MLO			= BIT(1),
 	WIPHY_FLAG_SPLIT_SCAN_6GHZ		= BIT(2),
 	WIPHY_FLAG_NETNS_OK			= BIT(3),
 	WIPHY_FLAG_PS_ON_BY_DEFAULT		= BIT(4),
@@ -5505,6 +5516,8 @@ static inline void wiphy_unlock(struct wiphy *wiphy)
  * @netdev: (private) Used to reference back to the netdev, may be %NULL
  * @identifier: (private) Identifier used in nl80211 to identify this
  *	wireless device if it has no netdev
+ * @connected_addr: (private) BSSID or AP MLD address if connected
+ * @connected: indicates if connected or not (STA mode)
  * @current_bss: (private) Used by the internal configuration code
  * @chandef: (private) Used by the internal configuration code to track
  *	the user-set channel definition.
@@ -5585,8 +5598,6 @@ struct wireless_dev {
 	u8 address[ETH_ALEN] __aligned(sizeof(u16));
 
 	/* currently used for IBSS and SME - might be rearranged later */
-	u8 ssid[IEEE80211_MAX_SSID_LEN];
-	u8 ssid_len, mesh_id_len, mesh_id_up_len;
 	struct cfg80211_conn *conn;
 	struct cfg80211_cached_keys *connect_keys;
 	enum ieee80211_bss_type conn_bss_type;
@@ -5598,20 +5609,17 @@ struct wireless_dev {
 	struct list_head event_list;
 	spinlock_t event_lock;
 
-	struct cfg80211_internal_bss *current_bss; /* associated / joined */
-	struct cfg80211_chan_def preset_chandef;
-	struct cfg80211_chan_def chandef;
+	u8 connected:1;
 
 	bool ps;
 	int ps_timeout;
 
-	int beacon_interval;
-
 	u32 ap_unexpected_nlportid;
 
 	u32 owner_nlportid;
 	bool nl_owner_dead;
 
+	/* FIXME: need to rework radar detection for MLO */
 	bool cac_started;
 	unsigned long cac_start_time;
 	unsigned int cac_time_ms;
@@ -5639,6 +5647,50 @@ struct wireless_dev {
 	struct work_struct pmsr_free_wk;
 
 	unsigned long unprot_beacon_reported;
+
+	union {
+		struct {
+			u8 connected_addr[ETH_ALEN] __aligned(2);
+			u8 ssid[IEEE80211_MAX_SSID_LEN];
+			u8 ssid_len;
+		} client;
+		struct {
+			int beacon_interval;
+			struct cfg80211_chan_def preset_chandef;
+			struct cfg80211_chan_def chandef;
+			u8 id[IEEE80211_MAX_SSID_LEN];
+			u8 id_len, id_up_len;
+		} mesh;
+		struct {
+			struct cfg80211_chan_def preset_chandef;
+			u8 ssid[IEEE80211_MAX_SSID_LEN];
+			u8 ssid_len;
+		} ap;
+		struct {
+			struct cfg80211_internal_bss *current_bss;
+			struct cfg80211_chan_def chandef;
+			int beacon_interval;
+			u8 ssid[IEEE80211_MAX_SSID_LEN];
+			u8 ssid_len;
+		} ibss;
+		struct {
+			struct cfg80211_chan_def chandef;
+		} ocb;
+	} u;
+
+	struct {
+		u8 addr[ETH_ALEN] __aligned(2);
+		union {
+			struct {
+				unsigned int beacon_interval;
+				struct cfg80211_chan_def chandef;
+			} ap;
+			struct {
+				struct cfg80211_internal_bss *current_bss;
+			} client;
+		};
+	} links[IEEE80211_MLD_MAX_NUM_LINKS];
+	u16 valid_links;
 };
 
 static inline const u8 *wdev_address(struct wireless_dev *wdev)
@@ -5668,6 +5720,31 @@ static inline void *wdev_priv(struct wireless_dev *wdev)
 }
 
 /**
+ * wdev_chandef - return chandef pointer from wireless_dev
+ * @wdev: the wdev
+ * @link_id: the link ID for MLO
+ *
+ * Return: The chandef depending on the mode, or %NULL.
+ */
+struct cfg80211_chan_def *wdev_chandef(struct wireless_dev *wdev,
+				       unsigned int link_id);
+
+static inline void WARN_INVALID_LINK_ID(struct wireless_dev *wdev,
+					unsigned int link_id)
+{
+	WARN_ON(link_id && !wdev->valid_links);
+	WARN_ON(wdev->valid_links &&
+		!(wdev->valid_links & BIT(link_id)));
+}
+
+#define for_each_valid_link(wdev, link_id)					\
+	for (link_id = 0;							\
+	     link_id < ((wdev)->valid_links ? ARRAY_SIZE((wdev)->links) : 1);	\
+	     link_id++)								\
+		if (!(wdev)->valid_links ||					\
+		    ((wdev)->valid_links & BIT(link_id)))
+
+/**
  * DOC: Utility functions
  *
  * cfg80211 offers a number of utility functions that can be useful.
@@ -7882,12 +7959,14 @@ bool cfg80211_reg_can_beacon_relax(struct wiphy *wiphy,
  * cfg80211_ch_switch_notify - update wdev channel and notify userspace
  * @dev: the device which switched channels
  * @chandef: the new channel definition
+ * @link_id: the link ID for MLO, must be 0 for non-MLO
  *
  * Caller must acquire wdev_lock, therefore must only be called from sleepable
  * driver context!
  */
 void cfg80211_ch_switch_notify(struct net_device *dev,
-			       struct cfg80211_chan_def *chandef);
+			       struct cfg80211_chan_def *chandef,
+			       unsigned int link_id);
 
 /*
  * cfg80211_ch_switch_started_notify - notify channel switch start
diff --git a/include/uapi/linux/nl80211.h b/include/uapi/linux/nl80211.h
index 98f905f16411..a9a2c9fef295 100644
--- a/include/uapi/linux/nl80211.h
+++ b/include/uapi/linux/nl80211.h
@@ -324,6 +324,17 @@
  */
 
 /**
+ * DOC: Multi-Link Operation
+ *
+ * In Multi-Link Operation, a connection between to MLDs utilizes multiple
+ * links. To use this in nl80211, various commands and responses now need
+ * to or will include the new %NL80211_ATTR_MLO_LINKS attribute.
+ * Additionally, various commands that need to operate on a specific link
+ * now need to be given the %NL80211_ATTR_MLO_LINK_ID attribute, e.g. to
+ * use %NL80211_CMD_START_AP or similar functions.
+ */
+
+/**
  * enum nl80211_commands - supported nl80211 commands
  *
  * @NL80211_CMD_UNSPEC: unspecified command to catch errors
@@ -1237,6 +1248,12 @@
  *      to describe the BSSID address of the AP and %NL80211_ATTR_TIMEOUT to
  *      specify the timeout value.
  *
+ * @NL80211_CMD_ADD_LINK: Add a new link to an interface. The
+ *	%NL80211_ATTR_MLO_LINK_ID attribute is used for the new link.
+ * @NL80211_CMD_REMOVE_LINK: Remove a link from an interface. This may come
+ *	without %NL80211_ATTR_MLO_LINK_ID as an easy way to remove all links
+ *	in preparation for e.g. roaming to a regular (non-MLO) AP.
+ *
  * @NL80211_CMD_MAX: highest used command number
  * @__NL80211_CMD_AFTER_LAST: internal use
  */
@@ -1481,6 +1498,9 @@ enum nl80211_commands {
 
 	NL80211_CMD_ASSOC_COMEBACK,
 
+	NL80211_CMD_ADD_LINK,
+	NL80211_CMD_REMOVE_LINK,
+
 	/* add new commands above here */
 
 	/* used to define NL80211_CMD_MAX below */
@@ -2663,6 +2683,11 @@ enum nl80211_commands {
  *	association request when used with NL80211_CMD_NEW_STATION). Can be set
  *	only if %NL80211_STA_FLAG_WME is set.
  *
+ * @NL80211_ATTR_MLO_LINK_ID: A (u8) link ID for use with MLO, to be used with
+ *	various commands that need a link ID to operate.
+ * @NL80211_ATTR_MLO_LINKS: A nested array of links, each containing some
+ *	per-link information and a link ID.
+ *
  * @NUM_NL80211_ATTR: total number of nl80211_attrs available
  * @NL80211_ATTR_MAX: highest attribute number currently defined
  * @__NL80211_ATTR_AFTER_LAST: internal use
@@ -3177,6 +3202,9 @@ enum nl80211_attrs {
 
 	NL80211_ATTR_DISABLE_EHT,
 
+	NL80211_ATTR_MLO_LINKS,
+	NL80211_ATTR_MLO_LINK_ID,
+
 	/* add attributes here, update the policy in nl80211.c */
 
 	__NL80211_ATTR_AFTER_LAST,