msft.c

// SPDX-License-Identifier: GPL-2.0-only
/*
 * Copyright (C) 2020 Google Corporation
 */

#include <net/bluetooth/bluetooth.h>
#include <net/bluetooth/hci_core.h>
#include <net/bluetooth/mgmt.h>

#include "mgmt_util.h"
#include "msft.h"

#define MSFT_RSSI_THRESHOLD_VALUE_MIN		-127
#define MSFT_RSSI_THRESHOLD_VALUE_MAX		20
#define MSFT_RSSI_LOW_TIMEOUT_MAX		0x3C

#define MSFT_OP_READ_SUPPORTED_FEATURES		0x00
struct msft_cp_read_supported_features {
	__u8   sub_opcode;
} __packed;

struct msft_rp_read_supported_features {
	__u8   status;
	__u8   sub_opcode;
	__le64 features;
	__u8   evt_prefix_len;
	__u8   evt_prefix[];
} __packed;

#define MSFT_OP_LE_MONITOR_ADVERTISEMENT	0x03
#define MSFT_MONITOR_ADVERTISEMENT_TYPE_PATTERN	0x01
struct msft_le_monitor_advertisement_pattern {
	__u8 length;
	__u8 data_type;
	__u8 start_byte;
	__u8 pattern[];
};

struct msft_le_monitor_advertisement_pattern_data {
	__u8 count;
	__u8 data[];
};

struct msft_cp_le_monitor_advertisement {
	__u8 sub_opcode;
	__s8 rssi_high;
	__s8 rssi_low;
	__u8 rssi_low_interval;
	__u8 rssi_sampling_period;
	__u8 cond_type;
	__u8 data[];
} __packed;

struct msft_rp_le_monitor_advertisement {
	__u8 status;
	__u8 sub_opcode;
	__u8 handle;
} __packed;

#define MSFT_OP_LE_CANCEL_MONITOR_ADVERTISEMENT	0x04
struct msft_cp_le_cancel_monitor_advertisement {
	__u8 sub_opcode;
	__u8 handle;
} __packed;

struct msft_rp_le_cancel_monitor_advertisement {
	__u8 status;
	__u8 sub_opcode;
} __packed;

#define MSFT_OP_LE_SET_ADVERTISEMENT_FILTER_ENABLE	0x05
struct msft_cp_le_set_advertisement_filter_enable {
	__u8 sub_opcode;
	__u8 enable;
} __packed;

struct msft_rp_le_set_advertisement_filter_enable {
	__u8 status;
	__u8 sub_opcode;
} __packed;

#define MSFT_EV_LE_MONITOR_DEVICE	0x02
struct msft_ev_le_monitor_device {
	__u8     addr_type;
	bdaddr_t bdaddr;
	__u8     monitor_handle;
	__u8     monitor_state;
} __packed;

struct msft_monitor_advertisement_handle_data {
	__u8  msft_handle;
	__u16 mgmt_handle;
	__s8 rssi_high;
	__s8 rssi_low;
	__u8 rssi_low_interval;
	__u8 rssi_sampling_period;
	__u8 cond_type;
	struct list_head list;
};

enum monitor_addr_filter_state {
	AF_STATE_IDLE,
	AF_STATE_ADDING,
	AF_STATE_ADDED,
	AF_STATE_REMOVING,
};

#define MSFT_MONITOR_ADVERTISEMENT_TYPE_ADDR	0x04
struct msft_monitor_addr_filter_data {
	__u8     msft_handle;
	__u8     pattern_handle; /* address filters pertain to */
	__u16    mgmt_handle;
	int      state;
	__s8     rssi_high;
	__s8     rssi_low;
	__u8     rssi_low_interval;
	__u8     rssi_sampling_period;
	__u8     addr_type;
	bdaddr_t bdaddr;
	struct list_head list;
};

struct msft_data {
	__u64 features;
	__u8  evt_prefix_len;
	__u8  *evt_prefix;
	struct list_head handle_map;
	struct list_head address_filters;
	__u8 resuming;
	__u8 suspending;
	__u8 filter_enabled;
	/* To synchronize add/remove address filter and monitor device event.*/
	struct mutex filter_lock;
};

bool msft_monitor_supported(struct hci_dev *hdev)
{
	return !!(msft_get_features(hdev) & MSFT_FEATURE_MASK_LE_ADV_MONITOR);
}

static bool read_supported_features(struct hci_dev *hdev,
				    struct msft_data *msft)
{
	struct msft_cp_read_supported_features cp;
	struct msft_rp_read_supported_features *rp;
	struct sk_buff *skb;

	cp.sub_opcode = MSFT_OP_READ_SUPPORTED_FEATURES;

	skb = __hci_cmd_sync(hdev, hdev->msft_opcode, sizeof(cp), &cp,
			     HCI_CMD_TIMEOUT);
	if (IS_ERR(skb)) {
		bt_dev_err(hdev, "Failed to read MSFT supported features (%ld)",
			   PTR_ERR(skb));
		return false;
	}

	if (skb->len < sizeof(*rp)) {
		bt_dev_err(hdev, "MSFT supported features length mismatch");
		goto failed;
	}

	rp = (struct msft_rp_read_supported_features *)skb->data;

	if (rp->sub_opcode != MSFT_OP_READ_SUPPORTED_FEATURES)
		goto failed;

	if (rp->evt_prefix_len > 0) {
		msft->evt_prefix = kmemdup(rp->evt_prefix, rp->evt_prefix_len,
					   GFP_KERNEL);
		if (!msft->evt_prefix)
			goto failed;
	}

	msft->evt_prefix_len = rp->evt_prefix_len;
	msft->features = __le64_to_cpu(rp->features);

	if (msft->features & MSFT_FEATURE_MASK_CURVE_VALIDITY)
		hdev->msft_curve_validity = true;

	kfree_skb(skb);
	return true;

failed:
	kfree_skb(skb);
	return false;
}

/* is_mgmt = true matches the handle exposed to userspace via mgmt.
 * is_mgmt = false matches the handle used by the msft controller.
 * This function requires the caller holds hdev->lock
 */
static struct msft_monitor_advertisement_handle_data *msft_find_handle_data
				(struct hci_dev *hdev, u16 handle, bool is_mgmt)
{
	struct msft_monitor_advertisement_handle_data *entry;
	struct msft_data *msft = hdev->msft_data;

	list_for_each_entry(entry, &msft->handle_map, list) {
		if (is_mgmt && entry->mgmt_handle == handle)
			return entry;
		if (!is_mgmt && entry->msft_handle == handle)
			return entry;
	}

	return NULL;
}

/* This function requires the caller holds msft->filter_lock */
static struct msft_monitor_addr_filter_data *msft_find_address_data
			(struct hci_dev *hdev, u8 addr_type, bdaddr_t *addr,
			 u8 pattern_handle)
{
	struct msft_monitor_addr_filter_data *entry;
	struct msft_data *msft = hdev->msft_data;

	list_for_each_entry(entry, &msft->address_filters, list) {
		if (entry->pattern_handle == pattern_handle &&
		    addr_type == entry->addr_type &&
		    !bacmp(addr, &entry->bdaddr))
			return entry;
	}

	return NULL;
}

/* This function requires the caller holds hdev->lock */
static int msft_monitor_device_del(struct hci_dev *hdev, __u16 mgmt_handle,
				   bdaddr_t *bdaddr, __u8 addr_type,
				   bool notify)
{
	struct monitored_device *dev, *tmp;
	int count = 0;

	list_for_each_entry_safe(dev, tmp, &hdev->monitored_devices, list) {
		/* mgmt_handle == 0 indicates remove all devices, whereas,
		 * bdaddr == NULL indicates remove all devices matching the
		 * mgmt_handle.
		 */
		if ((!mgmt_handle || dev->handle == mgmt_handle) &&
		    (!bdaddr || (!bacmp(bdaddr, &dev->bdaddr) &&
				 addr_type == dev->addr_type))) {
			if (notify && dev->notified) {
				mgmt_adv_monitor_device_lost(hdev, dev->handle,
							     &dev->bdaddr,
							     dev->addr_type);
			}

			list_del(&dev->list);
			kfree(dev);
			count++;
		}
	}

	return count;
}

static int msft_le_monitor_advertisement_cb(struct hci_dev *hdev, u16 opcode,
					    struct adv_monitor *monitor,
					    struct sk_buff *skb)
{
	struct msft_rp_le_monitor_advertisement *rp;
	struct msft_monitor_advertisement_handle_data *handle_data;
	struct msft_data *msft = hdev->msft_data;
	int status = 0;

	hci_dev_lock(hdev);

	rp = (struct msft_rp_le_monitor_advertisement *)skb->data;
	if (skb->len < sizeof(*rp)) {
		status = HCI_ERROR_UNSPECIFIED;
		goto unlock;
	}

	status = rp->status;
	if (status)
		goto unlock;

	handle_data = kmalloc(sizeof(*handle_data), GFP_KERNEL);
	if (!handle_data) {
		status = HCI_ERROR_UNSPECIFIED;
		goto unlock;
	}

	handle_data->mgmt_handle = monitor->handle;
	handle_data->msft_handle = rp->handle;
	handle_data->cond_type   = MSFT_MONITOR_ADVERTISEMENT_TYPE_PATTERN;
	INIT_LIST_HEAD(&handle_data->list);
	list_add(&handle_data->list, &msft->handle_map);

	monitor->state = ADV_MONITOR_STATE_OFFLOADED;

unlock:
	if (status)
		hci_free_adv_monitor(hdev, monitor);

	hci_dev_unlock(hdev);

	return status;
}

/* This function requires the caller holds hci_req_sync_lock */
static void msft_remove_addr_filters_sync(struct hci_dev *hdev, u8 handle)
{
	struct msft_monitor_addr_filter_data *address_filter, *n;
	struct msft_cp_le_cancel_monitor_advertisement cp;
	struct msft_data *msft = hdev->msft_data;
	struct list_head head;
	struct sk_buff *skb;

	INIT_LIST_HEAD(&head);

	/* Cancel all corresponding address monitors */
	mutex_lock(&msft->filter_lock);

	list_for_each_entry_safe(address_filter, n, &msft->address_filters,
				 list) {
		if (address_filter->pattern_handle != handle)
			continue;

		list_del(&address_filter->list);

		/* Keep the address filter and let
		 * msft_add_address_filter_sync() remove and free the address
		 * filter.
		 */
		if (address_filter->state == AF_STATE_ADDING) {
			address_filter->state = AF_STATE_REMOVING;
			continue;
		}

		/* Keep the address filter and let
		 * msft_cancel_address_filter_sync() remove and free the address
		 * filter
		 */
		if (address_filter->state == AF_STATE_REMOVING)
			continue;

		list_add_tail(&address_filter->list, &head);
	}

	mutex_unlock(&msft->filter_lock);

	list_for_each_entry_safe(address_filter, n, &head, list) {
		list_del(&address_filter->list);

		cp.sub_opcode = MSFT_OP_LE_CANCEL_MONITOR_ADVERTISEMENT;
		cp.handle = address_filter->msft_handle;

		skb = __hci_cmd_sync(hdev, hdev->msft_opcode, sizeof(cp), &cp,
				     HCI_CMD_TIMEOUT);
		if (IS_ERR(skb)) {
			kfree(address_filter);
			continue;
		}

		kfree_skb(skb);

		bt_dev_dbg(hdev, "MSFT: Canceled device %pMR address filter",
			   &address_filter->bdaddr);

		kfree(address_filter);
	}
}

static int msft_le_cancel_monitor_advertisement_cb(struct hci_dev *hdev,
						   u16 opcode,
						   struct adv_monitor *monitor,
						   struct sk_buff *skb)
{
	struct msft_rp_le_cancel_monitor_advertisement *rp;
	struct msft_monitor_advertisement_handle_data *handle_data;
	struct msft_data *msft = hdev->msft_data;
	int status = 0;
	u8 msft_handle;

	rp = (struct msft_rp_le_cancel_monitor_advertisement *)skb->data;
	if (skb->len < sizeof(*rp)) {
		status = HCI_ERROR_UNSPECIFIED;
		goto done;
	}

	status = rp->status;
	if (status)
		goto done;

	hci_dev_lock(hdev);

	handle_data = msft_find_handle_data(hdev, monitor->handle, true);

	if (handle_data) {
		if (monitor->state == ADV_MONITOR_STATE_OFFLOADED)
			monitor->state = ADV_MONITOR_STATE_REGISTERED;

		/* Do not free the monitor if it is being removed due to
		 * suspend. It will be re-monitored on resume.
		 */
		if (!msft->suspending) {
			hci_free_adv_monitor(hdev, monitor);

			/* Clear any monitored devices by this Adv Monitor */
			msft_monitor_device_del(hdev, handle_data->mgmt_handle,
						NULL, 0, false);
		}

		msft_handle = handle_data->msft_handle;

		list_del(&handle_data->list);
		kfree(handle_data);

		hci_dev_unlock(hdev);

		msft_remove_addr_filters_sync(hdev, msft_handle);
	} else {
		hci_dev_unlock(hdev);
	}

done:
	return status;
}

/* This function requires the caller holds hci_req_sync_lock */
static int msft_remove_monitor_sync(struct hci_dev *hdev,
				    struct adv_monitor *monitor)
{
	struct msft_cp_le_cancel_monitor_advertisement cp;
	struct msft_monitor_advertisement_handle_data *handle_data;
	struct sk_buff *skb;

	handle_data = msft_find_handle_data(hdev, monitor->handle, true);

	/* If no matched handle, just remove without telling controller */
	if (!handle_data)
		return -ENOENT;

	cp.sub_opcode = MSFT_OP_LE_CANCEL_MONITOR_ADVERTISEMENT;
	cp.handle = handle_data->msft_handle;

	skb = __hci_cmd_sync(hdev, hdev->msft_opcode, sizeof(cp), &cp,
			     HCI_CMD_TIMEOUT);
	if (IS_ERR(skb))
		return PTR_ERR(skb);

	return msft_le_cancel_monitor_advertisement_cb(hdev, hdev->msft_opcode,
						       monitor, skb);
}

/* This function requires the caller holds hci_req_sync_lock */
int msft_suspend_sync(struct hci_dev *hdev)
{
	struct msft_data *msft = hdev->msft_data;
	struct adv_monitor *monitor;
	int handle = 0;

	if (!msft || !msft_monitor_supported(hdev))
		return 0;

	msft->suspending = true;

	while (1) {
		monitor = idr_get_next(&hdev->adv_monitors_idr, &handle);
		if (!monitor)
			break;

		msft_remove_monitor_sync(hdev, monitor);

		handle++;
	}

	/* All monitors have been removed */
	msft->suspending = false;

	return 0;
}

static bool msft_monitor_rssi_valid(struct adv_monitor *monitor)
{
	struct adv_rssi_thresholds *r = &monitor->rssi;

	if (r->high_threshold < MSFT_RSSI_THRESHOLD_VALUE_MIN ||
	    r->high_threshold > MSFT_RSSI_THRESHOLD_VALUE_MAX ||
	    r->low_threshold < MSFT_RSSI_THRESHOLD_VALUE_MIN ||
	    r->low_threshold > MSFT_RSSI_THRESHOLD_VALUE_MAX)
		return false;

	/* High_threshold_timeout is not supported,
	 * once high_threshold is reached, events are immediately reported.
	 */
	if (r->high_threshold_timeout != 0)
		return false;

	if (r->low_threshold_timeout > MSFT_RSSI_LOW_TIMEOUT_MAX)
		return false;

	/* Sampling period from 0x00 to 0xFF are all allowed */
	return true;
}

static bool msft_monitor_pattern_valid(struct adv_monitor *monitor)
{
	return msft_monitor_rssi_valid(monitor);
	/* No additional check needed for pattern-based monitor */
}

static int msft_add_monitor_sync(struct hci_dev *hdev,
				 struct adv_monitor *monitor)
{
	struct msft_cp_le_monitor_advertisement *cp;
	struct msft_le_monitor_advertisement_pattern_data *pattern_data;
	struct msft_monitor_advertisement_handle_data *handle_data;
	struct msft_le_monitor_advertisement_pattern *pattern;
	struct adv_pattern *entry;
	size_t total_size = sizeof(*cp) + sizeof(*pattern_data);
	ptrdiff_t offset = 0;
	u8 pattern_count = 0;
	struct sk_buff *skb;
	int err;

	if (!msft_monitor_pattern_valid(monitor))
		return -EINVAL;

	list_for_each_entry(entry, &monitor->patterns, list) {
		pattern_count++;
		total_size += sizeof(*pattern) + entry->length;
	}

	cp = kmalloc(total_size, GFP_KERNEL);
	if (!cp)
		return -ENOMEM;

	cp->sub_opcode = MSFT_OP_LE_MONITOR_ADVERTISEMENT;
	cp->rssi_high = monitor->rssi.high_threshold;
	cp->rssi_low = monitor->rssi.low_threshold;
	cp->rssi_low_interval = (u8)monitor->rssi.low_threshold_timeout;
	cp->rssi_sampling_period = monitor->rssi.sampling_period;

	cp->cond_type = MSFT_MONITOR_ADVERTISEMENT_TYPE_PATTERN;

	pattern_data = (void *)cp->data;
	pattern_data->count = pattern_count;

	list_for_each_entry(entry, &monitor->patterns, list) {
		pattern = (void *)(pattern_data->data + offset);
		/* the length also includes data_type and offset */
		pattern->length = entry->length + 2;
		pattern->data_type = entry->ad_type;
		pattern->start_byte = entry->offset;
		memcpy(pattern->pattern, entry->value, entry->length);
		offset += sizeof(*pattern) + entry->length;
	}

	skb = __hci_cmd_sync(hdev, hdev->msft_opcode, total_size, cp,
			     HCI_CMD_TIMEOUT);

	if (IS_ERR(skb)) {
		err = PTR_ERR(skb);
		goto out_free;
	}

	err = msft_le_monitor_advertisement_cb(hdev, hdev->msft_opcode,
					       monitor, skb);
	if (err)
		goto out_free;

	handle_data = msft_find_handle_data(hdev, monitor->handle, true);
	if (!handle_data) {
		err = -ENODATA;
		goto out_free;
	}

	handle_data->rssi_high	= cp->rssi_high;
	handle_data->rssi_low	= cp->rssi_low;
	handle_data->rssi_low_interval	  = cp->rssi_low_interval;
	handle_data->rssi_sampling_period = cp->rssi_sampling_period;

out_free:
	kfree(cp);
	return err;
}

/* This function requires the caller holds hci_req_sync_lock */
static void reregister_monitor(struct hci_dev *hdev)
{
	struct adv_monitor *monitor;
	struct msft_data *msft = hdev->msft_data;
	int handle = 0;

	if (!msft)
		return;

	msft->resuming = true;

	while (1) {
		monitor = idr_get_next(&hdev->adv_monitors_idr, &handle);
		if (!monitor)
			break;

		msft_add_monitor_sync(hdev, monitor);

		handle++;
	}

	/* All monitors have been reregistered */
	msft->resuming = false;
}

/* This function requires the caller holds hci_req_sync_lock */
int msft_resume_sync(struct hci_dev *hdev)
{
	struct msft_data *msft = hdev->msft_data;

	if (!msft || !msft_monitor_supported(hdev))
		return 0;

	hci_dev_lock(hdev);

	/* Clear already tracked devices on resume. Once the monitors are
	 * reregistered, devices in range will be found again after resume.
	 */
	hdev->advmon_pend_notify = false;
	msft_monitor_device_del(hdev, 0, NULL, 0, true);

	hci_dev_unlock(hdev);

	reregister_monitor(hdev);

	return 0;
}

/* This function requires the caller holds hci_req_sync_lock */
void msft_do_open(struct hci_dev *hdev)
{
	struct msft_data *msft = hdev->msft_data;

	if (hdev->msft_opcode == HCI_OP_NOP)
		return;

	if (!msft) {
		bt_dev_err(hdev, "MSFT extension not registered");
		return;
	}

	bt_dev_dbg(hdev, "Initialize MSFT extension");

	/* Reset existing MSFT data before re-reading */
	kfree(msft->evt_prefix);
	msft->evt_prefix = NULL;
	msft->evt_prefix_len = 0;
	msft->features = 0;

	if (!read_supported_features(hdev, msft)) {
		hdev->msft_data = NULL;
		kfree(msft);
		return;
	}

	if (msft_monitor_supported(hdev)) {
		msft->resuming = true;
		msft_set_filter_enable(hdev, true);
		/* Monitors get removed on power off, so we need to explicitly
		 * tell the controller to re-monitor.
		 */
		reregister_monitor(hdev);
	}
}

void msft_do_close(struct hci_dev *hdev)
{
	struct msft_data *msft = hdev->msft_data;
	struct msft_monitor_advertisement_handle_data *handle_data, *tmp;
	struct msft_monitor_addr_filter_data *address_filter, *n;
	struct adv_monitor *monitor;

	if (!msft)
		return;

	bt_dev_dbg(hdev, "Cleanup of MSFT extension");

	/* The controller will silently remove all monitors on power off.
	 * Therefore, remove handle_data mapping and reset monitor state.
	 */
	list_for_each_entry_safe(handle_data, tmp, &msft->handle_map, list) {
		monitor = idr_find(&hdev->adv_monitors_idr,
				   handle_data->mgmt_handle);

		if (monitor && monitor->state == ADV_MONITOR_STATE_OFFLOADED)
			monitor->state = ADV_MONITOR_STATE_REGISTERED;

		list_del(&handle_data->list);
		kfree(handle_data);
	}

	mutex_lock(&msft->filter_lock);
	list_for_each_entry_safe(address_filter, n, &msft->address_filters,
				 list) {
		list_del(&address_filter->list);
		kfree(address_filter);
	}
	mutex_unlock(&msft->filter_lock);

	hci_dev_lock(hdev);

	/* Clear any devices that are being monitored and notify device lost */
	hdev->advmon_pend_notify = false;
	msft_monitor_device_del(hdev, 0, NULL, 0, true);

	hci_dev_unlock(hdev);
}

static int msft_cancel_address_filter_sync(struct hci_dev *hdev, void *data)
{
	struct msft_monitor_addr_filter_data *address_filter = data;
	struct msft_cp_le_cancel_monitor_advertisement cp;
	struct msft_data *msft = hdev->msft_data;
	struct sk_buff *skb;
	int err = 0;

	if (!msft) {
		bt_dev_err(hdev, "MSFT: msft data is freed");
		return -EINVAL;
	}

	/* The address filter has been removed by hci dev close */
	if (!test_bit(HCI_UP, &hdev->flags))
		return 0;

	mutex_lock(&msft->filter_lock);
	list_del(&address_filter->list);
	mutex_unlock(&msft->filter_lock);

	cp.sub_opcode = MSFT_OP_LE_CANCEL_MONITOR_ADVERTISEMENT;
	cp.handle = address_filter->msft_handle;

	skb = __hci_cmd_sync(hdev, hdev->msft_opcode, sizeof(cp), &cp,
			     HCI_CMD_TIMEOUT);
	if (IS_ERR(skb)) {
		bt_dev_err(hdev, "MSFT: Failed to cancel address (%pMR) filter",
			   &address_filter->bdaddr);
		err = PTR_ERR(skb);
		goto done;
	}
	kfree_skb(skb);

	bt_dev_dbg(hdev, "MSFT: Canceled device %pMR address filter",
		   &address_filter->bdaddr);

done:
	kfree(address_filter);

	return err;
}

void msft_register(struct hci_dev *hdev)
{
	struct msft_data *msft = NULL;

	bt_dev_dbg(hdev, "Register MSFT extension");

	msft = kzalloc(sizeof(*msft), GFP_KERNEL);
	if (!msft) {
		bt_dev_err(hdev, "Failed to register MSFT extension");
		return;
	}

	INIT_LIST_HEAD(&msft->handle_map);
	INIT_LIST_HEAD(&msft->address_filters);
	hdev->msft_data = msft;
	mutex_init(&msft->filter_lock);
}

void msft_release(struct hci_dev *hdev)
{
	struct msft_data *msft = hdev->msft_data;

	if (!msft)
		return;

	bt_dev_dbg(hdev, "Unregister MSFT extension");

	hdev->msft_data = NULL;

	kfree(msft->evt_prefix);
	mutex_destroy(&msft->filter_lock);
	kfree(msft);
}

/* This function requires the caller holds hdev->lock */
static void msft_device_found(struct hci_dev *hdev, bdaddr_t *bdaddr,
			      __u8 addr_type, __u16 mgmt_handle)
{
	struct monitored_device *dev;

	dev = kmalloc(sizeof(*dev), GFP_KERNEL);
	if (!dev) {
		bt_dev_err(hdev, "MSFT vendor event %u: no memory",
			   MSFT_EV_LE_MONITOR_DEVICE);
		return;
	}

	bacpy(&dev->bdaddr, bdaddr);
	dev->addr_type = addr_type;
	dev->handle = mgmt_handle;
	dev->notified = false;

	INIT_LIST_HEAD(&dev->list);
	list_add(&dev->list, &hdev->monitored_devices);
	hdev->advmon_pend_notify = true;
}

/* This function requires the caller holds hdev->lock */
static void msft_device_lost(struct hci_dev *hdev, bdaddr_t *bdaddr,
			     __u8 addr_type, __u16 mgmt_handle)
{
	if (!msft_monitor_device_del(hdev, mgmt_handle, bdaddr, addr_type,
				     true)) {
		bt_dev_err(hdev, "MSFT vendor event %u: dev %pMR not in list",
			   MSFT_EV_LE_MONITOR_DEVICE, bdaddr);
	}
}

static void *msft_skb_pull(struct hci_dev *hdev, struct sk_buff *skb,
			   u8 ev, size_t len)
{
	void *data;

	data = skb_pull_data(skb, len);
	if (!data)
		bt_dev_err(hdev, "Malformed MSFT vendor event: 0x%02x", ev);

	return data;
}

static int msft_add_address_filter_sync(struct hci_dev *hdev, void *data)
{
	struct msft_monitor_addr_filter_data *address_filter = data;
	struct msft_rp_le_monitor_advertisement *rp;
	struct msft_cp_le_monitor_advertisement *cp;
	struct msft_data *msft = hdev->msft_data;
	struct sk_buff *skb = NULL;
	bool remove = false;
	size_t size;

	if (!msft) {
		bt_dev_err(hdev, "MSFT: msft data is freed");
		return -EINVAL;
	}

	/* The address filter has been removed by hci dev close */
	if (!test_bit(HCI_UP, &hdev->flags))
		return -ENODEV;

	/* We are safe to use the address filter from now on.
	 * msft_monitor_device_evt() wouldn't delete this filter because it's
	 * not been added by now.
	 * And all other functions that requiring hci_req_sync_lock wouldn't
	 * touch this filter before this func completes because it's protected
	 * by hci_req_sync_lock.
	 */

	if (address_filter->state == AF_STATE_REMOVING) {
		mutex_lock(&msft->filter_lock);
		list_del(&address_filter->list);
		mutex_unlock(&msft->filter_lock);
		kfree(address_filter);
		return 0;
	}

	size = sizeof(*cp) +
	       sizeof(address_filter->addr_type) +
	       sizeof(address_filter->bdaddr);
	cp = kzalloc(size, GFP_KERNEL);
	if (!cp) {
		bt_dev_err(hdev, "MSFT: Alloc cmd param err");
		remove = true;
		goto done;
	}

	cp->sub_opcode           = MSFT_OP_LE_MONITOR_ADVERTISEMENT;
	cp->rssi_high		 = address_filter->rssi_high;
	cp->rssi_low		 = address_filter->rssi_low;
	cp->rssi_low_interval    = address_filter->rssi_low_interval;
	cp->rssi_sampling_period = address_filter->rssi_sampling_period;
	cp->cond_type            = MSFT_MONITOR_ADVERTISEMENT_TYPE_ADDR;
	cp->data[0]              = address_filter->addr_type;
	memcpy(&cp->data[1], &address_filter->bdaddr,
	       sizeof(address_filter->bdaddr));

	skb = __hci_cmd_sync(hdev, hdev->msft_opcode, size, cp,
			     HCI_CMD_TIMEOUT);
	kfree(cp);

	if (IS_ERR(skb)) {
		bt_dev_err(hdev, "Failed to enable address %pMR filter",
			   &address_filter->bdaddr);
		skb = NULL;
		remove = true;
		goto done;
	}

	rp = skb_pull_data(skb, sizeof(*rp));
	if (!rp || rp->sub_opcode != MSFT_OP_LE_MONITOR_ADVERTISEMENT ||
	    rp->status)
		remove = true;

done:
	mutex_lock(&msft->filter_lock);

	if (remove) {
		bt_dev_warn(hdev, "MSFT: Remove address (%pMR) filter",
			    &address_filter->bdaddr);
		list_del(&address_filter->list);
		kfree(address_filter);
	} else {
		address_filter->state = AF_STATE_ADDED;
		address_filter->msft_handle = rp->handle;
		bt_dev_dbg(hdev, "MSFT: Address %pMR filter enabled",
			   &address_filter->bdaddr);
	}
	mutex_unlock(&msft->filter_lock);

	kfree_skb(skb);

	return 0;
}

/* This function requires the caller holds msft->filter_lock */
static struct msft_monitor_addr_filter_data *msft_add_address_filter
		(struct hci_dev *hdev, u8 addr_type, bdaddr_t *bdaddr,
		 struct msft_monitor_advertisement_handle_data *handle_data)
{
	struct msft_monitor_addr_filter_data *address_filter = NULL;
	struct msft_data *msft = hdev->msft_data;
	int err;

	address_filter = kzalloc(sizeof(*address_filter), GFP_KERNEL);
	if (!address_filter)
		return NULL;

	address_filter->state             = AF_STATE_ADDING;
	address_filter->msft_handle       = 0xff;
	address_filter->pattern_handle    = handle_data->msft_handle;
	address_filter->mgmt_handle       = handle_data->mgmt_handle;
	address_filter->rssi_high         = handle_data->rssi_high;
	address_filter->rssi_low          = handle_data->rssi_low;
	address_filter->rssi_low_interval = handle_data->rssi_low_interval;
	address_filter->rssi_sampling_period = handle_data->rssi_sampling_period;
	address_filter->addr_type            = addr_type;
	bacpy(&address_filter->bdaddr, bdaddr);

	/* With the above AF_STATE_ADDING, duplicated address filter can be
	 * avoided when receiving monitor device event (found/lost) frequently
	 * for the same device.
	 */
	list_add_tail(&address_filter->list, &msft->address_filters);

	err = hci_cmd_sync_queue(hdev, msft_add_address_filter_sync,
				 address_filter, NULL);
	if (err < 0) {
		bt_dev_err(hdev, "MSFT: Add address %pMR filter err", bdaddr);
		list_del(&address_filter->list);
		kfree(address_filter);
		return NULL;
	}

	bt_dev_dbg(hdev, "MSFT: Add device %pMR address filter",
		   &address_filter->bdaddr);

	return address_filter;
}

/* This function requires the caller holds hdev->lock */
static void msft_monitor_device_evt(struct hci_dev *hdev, struct sk_buff *skb)
{
	struct msft_monitor_addr_filter_data *n, *address_filter = NULL;
	struct msft_ev_le_monitor_device *ev;
	struct msft_monitor_advertisement_handle_data *handle_data;
	struct msft_data *msft = hdev->msft_data;
	u16 mgmt_handle = 0xffff;
	u8 addr_type;

	ev = msft_skb_pull(hdev, skb, MSFT_EV_LE_MONITOR_DEVICE, sizeof(*ev));
	if (!ev)
		return;

	bt_dev_dbg(hdev,
		   "MSFT vendor event 0x%02x: handle 0x%04x state %d addr %pMR",
		   MSFT_EV_LE_MONITOR_DEVICE, ev->monitor_handle,
		   ev->monitor_state, &ev->bdaddr);

	handle_data = msft_find_handle_data(hdev, ev->monitor_handle, false);

	if (!hci_test_quirk(hdev, HCI_QUIRK_USE_MSFT_EXT_ADDRESS_FILTER)) {
		if (!handle_data)
			return;
		mgmt_handle = handle_data->mgmt_handle;
		goto report_state;
	}

	if (handle_data) {
		/* Don't report any device found/lost event from pattern
		 * monitors. Pattern monitor always has its address filters for
		 * tracking devices.
		 */

		address_filter = msft_find_address_data(hdev, ev->addr_type,
							&ev->bdaddr,
							handle_data->msft_handle);
		if (address_filter)
			return;

		if (ev->monitor_state && handle_data->cond_type ==
				MSFT_MONITOR_ADVERTISEMENT_TYPE_PATTERN)
			msft_add_address_filter(hdev, ev->addr_type,
						&ev->bdaddr, handle_data);

		return;
	}

	/* This device event is not from pattern monitor.
	 * Report it if there is a corresponding address_filter for it.
	 */
	list_for_each_entry(n, &msft->address_filters, list) {
		if (n->state == AF_STATE_ADDED &&
		    n->msft_handle == ev->monitor_handle) {
			mgmt_handle = n->mgmt_handle;
			address_filter = n;
			break;
		}
	}

	if (!address_filter) {
		bt_dev_warn(hdev, "MSFT: Unexpected device event %pMR, %u, %u",
			    &ev->bdaddr, ev->monitor_handle, ev->monitor_state);
		return;
	}

report_state:
	switch (ev->addr_type) {
	case ADDR_LE_DEV_PUBLIC:
		addr_type = BDADDR_LE_PUBLIC;
		break;

	case ADDR_LE_DEV_RANDOM:
		addr_type = BDADDR_LE_RANDOM;
		break;

	default:
		bt_dev_err(hdev,
			   "MSFT vendor event 0x%02x: unknown addr type 0x%02x",
			   MSFT_EV_LE_MONITOR_DEVICE, ev->addr_type);
		return;
	}

	if (ev->monitor_state) {
		msft_device_found(hdev, &ev->bdaddr, addr_type, mgmt_handle);
	} else {
		if (address_filter && address_filter->state == AF_STATE_ADDED) {
			address_filter->state = AF_STATE_REMOVING;
			hci_cmd_sync_queue(hdev,
					   msft_cancel_address_filter_sync,
					   address_filter,
					   NULL);
		}
		msft_device_lost(hdev, &ev->bdaddr, addr_type, mgmt_handle);
	}
}

void msft_vendor_evt(struct hci_dev *hdev, void *data, struct sk_buff *skb)
{
	struct msft_data *msft = hdev->msft_data;
	u8 *evt_prefix;
	u8 *evt;

	if (!msft)
		return;

	/* When the extension has defined an event prefix, check that it
	 * matches, and otherwise just return.
	 */
	if (msft->evt_prefix_len > 0) {
		evt_prefix = msft_skb_pull(hdev, skb, 0, msft->evt_prefix_len);
		if (!evt_prefix)
			return;

		if (memcmp(evt_prefix, msft->evt_prefix, msft->evt_prefix_len))
			return;
	}

	/* Every event starts at least with an event code and the rest of
	 * the data is variable and depends on the event code.
	 */
	if (skb->len < 1)
		return;

	evt = msft_skb_pull(hdev, skb, 0, sizeof(*evt));
	if (!evt)
		return;

	hci_dev_lock(hdev);

	switch (*evt) {
	case MSFT_EV_LE_MONITOR_DEVICE:
		mutex_lock(&msft->filter_lock);
		msft_monitor_device_evt(hdev, skb);
		mutex_unlock(&msft->filter_lock);
		break;

	default:
		bt_dev_dbg(hdev, "MSFT vendor event 0x%02x", *evt);
		break;
	}

	hci_dev_unlock(hdev);
}

__u64 msft_get_features(struct hci_dev *hdev)
{
	struct msft_data *msft = hdev->msft_data;

	return msft ? msft->features : 0;
}

static void msft_le_set_advertisement_filter_enable_cb(struct hci_dev *hdev,
						       void *user_data,
						       u8 status)
{
	struct msft_cp_le_set_advertisement_filter_enable *cp = user_data;
	struct msft_data *msft = hdev->msft_data;

	/* Error 0x0C would be returned if the filter enabled status is
	 * already set to whatever we were trying to set.
	 * Although the default state should be disabled, some controller set
	 * the initial value to enabled. Because there is no way to know the
	 * actual initial value before sending this command, here we also treat
	 * error 0x0C as success.
	 */
	if (status != 0x00 && status != 0x0C)
		return;

	hci_dev_lock(hdev);

	msft->filter_enabled = cp->enable;

	if (status == 0x0C)
		bt_dev_warn(hdev, "MSFT filter_enable is already %s",
			    cp->enable ? "on" : "off");

	hci_dev_unlock(hdev);
}

/* This function requires the caller holds hci_req_sync_lock */
int msft_add_monitor_pattern(struct hci_dev *hdev, struct adv_monitor *monitor)
{
	struct msft_data *msft = hdev->msft_data;

	if (!msft)
		return -EOPNOTSUPP;

	if (msft->resuming || msft->suspending)
		return -EBUSY;

	return msft_add_monitor_sync(hdev, monitor);
}

/* This function requires the caller holds hci_req_sync_lock */
int msft_remove_monitor(struct hci_dev *hdev, struct adv_monitor *monitor)
{
	struct msft_data *msft = hdev->msft_data;

	if (!msft)
		return -EOPNOTSUPP;

	if (msft->resuming || msft->suspending)
		return -EBUSY;

	return msft_remove_monitor_sync(hdev, monitor);
}

int msft_set_filter_enable(struct hci_dev *hdev, bool enable)
{
	struct msft_cp_le_set_advertisement_filter_enable cp;
	struct msft_data *msft = hdev->msft_data;
	int err;

	if (!msft)
		return -EOPNOTSUPP;

	cp.sub_opcode = MSFT_OP_LE_SET_ADVERTISEMENT_FILTER_ENABLE;
	cp.enable = enable;
	err = __hci_cmd_sync_status(hdev, hdev->msft_opcode, sizeof(cp), &cp,
				    HCI_CMD_TIMEOUT);

	msft_le_set_advertisement_filter_enable_cb(hdev, &cp, err);

	return 0;
}

bool msft_curve_validity(struct hci_dev *hdev)
{
	return hdev->msft_curve_validity;
}