subsys/bluetooth/host/keys.h

/* keys.h - Bluetooth key handling */

/*
 * Copyright (c) 2015-2016 Intel Corporation
 *
 * SPDX-License-Identifier: Apache-2.0
 */

#ifndef ZEPHYR_SUBSYS_BLUETOOTH_HOST_KEYS_H_
#define ZEPHYR_SUBSYS_BLUETOOTH_HOST_KEYS_H_

#include <zephyr/bluetooth/bluetooth.h>

/** @cond INTERNAL_HIDDEN */

enum bt_keys_type {
	BT_KEYS_PERIPH_LTK     = BIT(0),
	BT_KEYS_IRK            = BIT(1),
	BT_KEYS_LTK            = BIT(2),
	BT_KEYS_LOCAL_CSRK     = BIT(3),
	BT_KEYS_REMOTE_CSRK    = BIT(4),
	BT_KEYS_LTK_P256       = BIT(5),

	BT_KEYS_ALL            = (BT_KEYS_PERIPH_LTK | BT_KEYS_IRK |
				  BT_KEYS_LTK | BT_KEYS_LOCAL_CSRK |
				  BT_KEYS_REMOTE_CSRK | BT_KEYS_LTK_P256),
};

enum {
	BT_KEYS_ID_PENDING_ADD  = BIT(0),
	BT_KEYS_ID_PENDING_DEL  = BIT(1),
	BT_KEYS_ID_ADDED        = BIT(2),
};

enum {
	BT_KEYS_AUTHENTICATED   = BIT(0),
	BT_KEYS_DEBUG           = BIT(1),
	/* Bit 2 and 3 might accidentally exist in old stored keys */
	BT_KEYS_SC              = BIT(4),
	BT_KEYS_OOB             = BIT(5),
};

struct bt_ltk {
	uint8_t                    rand[8];
	uint8_t                    ediv[2];
	uint8_t                    val[16];
};

struct bt_irk {
	uint8_t                    val[16];
	/* Cache for `bt_keys_find_irk`. Not reliable as "current RPA"! */
	bt_addr_t               rpa;
};

static inline bool bt_irk_eq(struct bt_irk const *a, struct bt_irk const *b)
{
	return (memcmp(a->val, b->val, sizeof(a->val)) == 0);
}

struct bt_csrk {
	uint8_t                    val[16];
	uint32_t                   cnt;
};

struct bt_keys {
	uint8_t                    id;
	bt_addr_le_t            addr;
	uint8_t                    state;
	uint8_t                    storage_start[0] __aligned(sizeof(void *));
	uint8_t                    enc_size;
	uint8_t                    flags;
	uint16_t                   keys;
	struct bt_ltk           ltk;
	struct bt_irk           irk;
#if defined(CONFIG_BT_SIGNING)
	struct bt_csrk          local_csrk;
	struct bt_csrk          remote_csrk;
#endif /* BT_SIGNING */
#if !defined(CONFIG_BT_SMP_SC_PAIR_ONLY)
	struct bt_ltk           periph_ltk;
#endif /* CONFIG_BT_SMP_SC_PAIR_ONLY */
#if (defined(CONFIG_BT_KEYS_OVERWRITE_OLDEST))
	uint32_t                   aging_counter;
#endif /* CONFIG_BT_KEYS_OVERWRITE_OLDEST */
};

#define BT_KEYS_STORAGE_LEN     (sizeof(struct bt_keys) - \
				 offsetof(struct bt_keys, storage_start))

/** Clears all keys.
 *
 * Keys stored in settings are not cleared.
 */
void bt_keys_reset(void);

/**
 * @brief Get a call through the callback for each key with the same type
 *
 * @param type Key type.
 * @param func Callback function to be called when a matched record is found.
 * @param data User data to be passed to the callback function.
 */
void bt_keys_foreach_type(enum bt_keys_type type, void (*func)(struct bt_keys *keys, void *data),
			  void *data);

/**
 * @brief Get the key slot reference for an ID and address pair.
 *
 * If the pair already exists in the keys pool, no new reference is reserved
 * and the same reference is returned directly.
 * Otherwise try to reserve one for the new ID and address pair if there is
 * a room for the new pair.
 *
 * @note If 'CONFIG_BT_KEYS_OVERWRITE_OLDEST' is defined and the keys pool is full,
 *       the function will try to find the oldest key that isn't in use with a connection.
 *       If a key with matched criteria is found, it will be overwritten with the new one.
 *
 * @param id Key identifier.
 * @param addr Destination address.
 *
 * @return A valid reference pointer to the key slot if process succeeded.
 *         Otherwise, a NULL value is returned.
 */
struct bt_keys *bt_keys_get_addr(uint8_t id, const bt_addr_le_t *addr);

/**
 * @brief Get the key slot reference for an ID and address pair with a certain type.
 *
 * If the pair already exists in the keys pool, no new reference is reserved
 * and the same reference is returned directly.
 * Otherwise try to reserve one for the new ID and address pair if there is
 * a room for the new pair and set the type.
 *
 * @param type Key type.
 * @param id Key identifier.
 * @param addr Destination address.
 *
 * @return A valid reference pointer to the key slot if process succeeded.
 *         Otherwise, a NULL value is returned.
 */
struct bt_keys *bt_keys_get_type(enum bt_keys_type type, uint8_t id, const bt_addr_le_t *addr);

/**
 * @brief Find key identified by type, ID and address
 *
 * @param type Key type.
 * @param id Key identifier.
 * @param addr Destination address.
 *
 * @return A valid reference pointer to the key slot if it exists.
 *         Otherwise, a NULL value is returned.
 */
struct bt_keys *bt_keys_find(enum bt_keys_type type, uint8_t id, const bt_addr_le_t *addr);

/**
 * @brief Find key reference by trying to resolve an RPA using IRK
 *
 * @param id Key identifier.
 * @param addr Destination address.
 * @return A valid reference pointer to the key slot on success.
 *         Otherwise, a NULL value is returned.
 */
struct bt_keys *bt_keys_find_irk(uint8_t id, const bt_addr_le_t *addr);

/**
 * @brief Find a key by ID and address
 *
 * @param id Key identifier.
 * @param addr Destination address.
 * @return A valid reference pointer to the key slot if it exists.
 *         Otherwise, a NULL value is returned.
 */
struct bt_keys *bt_keys_find_addr(uint8_t id, const bt_addr_le_t *addr);

/**
 * @brief Add a type to a key
 *
 * @param keys Key reference.
 * @param type Key type to be added.
 */
void bt_keys_add_type(struct bt_keys *keys, enum bt_keys_type type);

/**
 * @brief Clear a key contents
 *
 * @param keys Key reference to be cleared.
 */
void bt_keys_clear(struct bt_keys *keys);

#if defined(CONFIG_BT_SETTINGS)

/**
 * @brief Store key to persistent memory
 *
 * @param keys Key reference.
 * @return 0 on success, non-zero error code otherwise
 */
int bt_keys_store(struct bt_keys *keys);
#else
static inline int bt_keys_store(struct bt_keys *keys)
{
	return 0;
}
#endif

enum {
	BT_LINK_KEY_AUTHENTICATED  = BIT(0),
	BT_LINK_KEY_DEBUG          = BIT(1),
	BT_LINK_KEY_SC             = BIT(2),
};

struct bt_keys_link_key {
	bt_addr_t               addr;
	uint8_t                 storage_start[0]  __aligned(sizeof(void *));
	uint8_t                 flags;
	uint8_t                 val[16];
#if (defined(CONFIG_BT_KEYS_OVERWRITE_OLDEST))
	uint32_t                aging_counter;
#endif /* CONFIG_BT_KEYS_OVERWRITE_OLDEST */
};
#define BT_KEYS_LINK_KEY_STORAGE_LEN     (sizeof(struct bt_keys_link_key) - \
	offsetof(struct bt_keys_link_key, storage_start))

struct bt_keys_link_key *bt_keys_get_link_key(const bt_addr_t *addr);
struct bt_keys_link_key *bt_keys_find_link_key(const bt_addr_t *addr);
void bt_keys_link_key_clear(struct bt_keys_link_key *link_key);
void bt_keys_link_key_clear_addr(const bt_addr_t *addr);
void bt_keys_link_key_store(struct bt_keys_link_key *link_key);
void bt_foreach_bond_br(void (*func)(const struct bt_bond_info *info, void *user_data),
			void *user_data);

/* This function is used to signal that the key has been used for paring */
/* It updates the aging counter and saves it to flash if configuration option */
/* BT_KEYS_SAVE_AGING_COUNTER_ON_PAIRING is enabled */
void bt_keys_update_usage(uint8_t id, const bt_addr_le_t *addr);
void bt_keys_link_key_update_usage(const bt_addr_t *addr);

void bt_keys_show_sniffer_info(struct bt_keys *keys, void *data);

/** @endcond */

#endif /* ZEPHYR_SUBSYS_BLUETOOTH_HOST_KEYS_H_ */