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zephyr/subsys/bluetooth/host/keys.c
Théo Battrel 37cac7f2e2 Bluetooth: Host: Use custom API for Bluetooth settings 
This commit wrap the `settings_set_one` and `settings_delete` functions
in `bt_settings_store_one` and `bt_settings_delete`. By doing that the
Bluetooth settings can be managed in a single place.

This commit also introduce a new API to manage Bluetooth storage with
`bt_settings_store_*` and `bt_settings_delete_*` functions. Each
Bluetooth settings key have their own store and delete functions. Doing
that so custom behavior for key can be done if necessary.

This change is motivated by a need of keeping track of different
persistently stored settings inside the Bluetooth subsystem. This will
allow a better management of the settings that the Bluetooth subsystem
is responsible of.

Signed-off-by: Théo Battrel <theo.battrel@nordicsemi.no>
2023-06-17 07:58:07 -04:00

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/* keys.c - Bluetooth key handling */
/*
* Copyright (c) 2015-2016 Intel Corporation
*
* SPDX-License-Identifier: Apache-2.0
*/
#include <zephyr/kernel.h>
#include <string.h>
#include <stdlib.h>
#include <zephyr/sys/atomic.h>
#include <zephyr/sys/util.h>
#include <zephyr/sys/byteorder.h>
#include <zephyr/settings/settings.h>
#include <zephyr/bluetooth/bluetooth.h>
#include <zephyr/bluetooth/buf.h>
#include <zephyr/bluetooth/conn.h>
#include <zephyr/bluetooth/hci.h>
#include "common/bt_str.h"
#include "common/rpa.h"
#include "conn_internal.h"
#include "gatt_internal.h"
#include "hci_core.h"
#include "smp.h"
#include "settings.h"
#include "keys.h"
#define LOG_LEVEL CONFIG_BT_KEYS_LOG_LEVEL
#include <zephyr/logging/log.h>
LOG_MODULE_REGISTER(bt_keys);
static struct bt_keys key_pool[CONFIG_BT_MAX_PAIRED];
#define BT_KEYS_STORAGE_LEN_COMPAT (BT_KEYS_STORAGE_LEN - sizeof(uint32_t))
#if defined(CONFIG_BT_KEYS_OVERWRITE_OLDEST)
static uint32_t aging_counter_val;
static struct bt_keys *last_keys_updated;
struct key_data {
bool in_use;
uint8_t id;
};
static void find_key_in_use(struct bt_conn *conn, void *data)
{
struct key_data *kdata = data;
struct bt_keys *key;
__ASSERT_NO_MSG(conn != NULL);
__ASSERT_NO_MSG(data != NULL);
if (conn->state == BT_CONN_CONNECTED) {
key = bt_keys_find_addr(conn->id, bt_conn_get_dst(conn));
if (key == NULL) {
return;
}
/* Ensure that the reference returned matches the current pool item */
if (key == &key_pool[kdata->id]) {
kdata->in_use = true;
LOG_DBG("Connected device %s is using key_pool[%d]",
bt_addr_le_str(bt_conn_get_dst(conn)), kdata->id);
}
}
}
static bool key_is_in_use(uint8_t id)
{
struct key_data kdata = { false, id };
bt_conn_foreach(BT_CONN_TYPE_ALL, find_key_in_use, &kdata);
return kdata.in_use;
}
#endif /* CONFIG_BT_KEYS_OVERWRITE_OLDEST */
struct bt_keys *bt_keys_get_addr(uint8_t id, const bt_addr_le_t *addr)
{
struct bt_keys *keys;
int i;
size_t first_free_slot = ARRAY_SIZE(key_pool);
__ASSERT_NO_MSG(addr != NULL);
LOG_DBG("%s", bt_addr_le_str(addr));
for (i = 0; i < ARRAY_SIZE(key_pool); i++) {
keys = &key_pool[i];
if (keys->id == id && bt_addr_le_eq(&keys->addr, addr)) {
return keys;
}
if (first_free_slot == ARRAY_SIZE(key_pool) &&
bt_addr_le_eq(&keys->addr, BT_ADDR_LE_ANY)) {
first_free_slot = i;
}
}
#if defined(CONFIG_BT_KEYS_OVERWRITE_OLDEST)
if (first_free_slot == ARRAY_SIZE(key_pool)) {
struct bt_keys *oldest = NULL;
bt_addr_le_t oldest_addr;
for (i = 0; i < ARRAY_SIZE(key_pool); i++) {
struct bt_keys *current = &key_pool[i];
bool key_in_use = key_is_in_use(i);
if (key_in_use) {
continue;
}
if ((oldest == NULL) || (current->aging_counter < oldest->aging_counter)) {
oldest = current;
}
}
if (oldest == NULL) {
LOG_DBG("unable to create keys for %s", bt_addr_le_str(addr));
return NULL;
}
/* Use a copy as bt_unpair will clear the oldest key. */
bt_addr_le_copy(&oldest_addr, &oldest->addr);
bt_unpair(oldest->id, &oldest_addr);
if (bt_addr_le_eq(&oldest->addr, BT_ADDR_LE_ANY)) {
first_free_slot = oldest - &key_pool[0];
}
}
#endif /* CONFIG_BT_KEYS_OVERWRITE_OLDEST */
if (first_free_slot < ARRAY_SIZE(key_pool)) {
keys = &key_pool[first_free_slot];
keys->id = id;
bt_addr_le_copy(&keys->addr, addr);
#if defined(CONFIG_BT_KEYS_OVERWRITE_OLDEST)
keys->aging_counter = ++aging_counter_val;
last_keys_updated = keys;
#endif /* CONFIG_BT_KEYS_OVERWRITE_OLDEST */
LOG_DBG("created %p for %s", keys, bt_addr_le_str(addr));
return keys;
}
LOG_DBG("unable to create keys for %s", bt_addr_le_str(addr));
return NULL;
}
void bt_foreach_bond(uint8_t id, void (*func)(const struct bt_bond_info *info,
void *user_data),
void *user_data)
{
int i;
__ASSERT_NO_MSG(func != NULL);
for (i = 0; i < ARRAY_SIZE(key_pool); i++) {
struct bt_keys *keys = &key_pool[i];
if (keys->keys && keys->id == id) {
struct bt_bond_info info;
bt_addr_le_copy(&info.addr, &keys->addr);
func(&info, user_data);
}
}
}
void bt_keys_foreach_type(enum bt_keys_type type, void (*func)(struct bt_keys *keys, void *data),
void *data)
{
int i;
__ASSERT_NO_MSG(func != NULL);
for (i = 0; i < ARRAY_SIZE(key_pool); i++) {
if ((key_pool[i].keys & type)) {
func(&key_pool[i], data);
}
}
}
struct bt_keys *bt_keys_find(enum bt_keys_type type, uint8_t id, const bt_addr_le_t *addr)
{
int i;
__ASSERT_NO_MSG(addr != NULL);
LOG_DBG("type %d %s", type, bt_addr_le_str(addr));
for (i = 0; i < ARRAY_SIZE(key_pool); i++) {
if ((key_pool[i].keys & type) && key_pool[i].id == id &&
bt_addr_le_eq(&key_pool[i].addr, addr)) {
return &key_pool[i];
}
}
return NULL;
}
struct bt_keys *bt_keys_get_type(enum bt_keys_type type, uint8_t id, const bt_addr_le_t *addr)
{
struct bt_keys *keys;
__ASSERT_NO_MSG(addr != NULL);
LOG_DBG("type %d %s", type, bt_addr_le_str(addr));
keys = bt_keys_find(type, id, addr);
if (keys) {
return keys;
}
keys = bt_keys_get_addr(id, addr);
if (!keys) {
return NULL;
}
bt_keys_add_type(keys, type);
return keys;
}
struct bt_keys *bt_keys_find_irk(uint8_t id, const bt_addr_le_t *addr)
{
int i;
__ASSERT_NO_MSG(addr != NULL);
LOG_DBG("%s", bt_addr_le_str(addr));
if (!bt_addr_le_is_rpa(addr)) {
return NULL;
}
for (i = 0; i < ARRAY_SIZE(key_pool); i++) {
if (!(key_pool[i].keys & BT_KEYS_IRK)) {
continue;
}
if (key_pool[i].id == id &&
bt_addr_eq(&addr->a, &key_pool[i].irk.rpa)) {
LOG_DBG("cached RPA %s for %s", bt_addr_str(&key_pool[i].irk.rpa),
bt_addr_le_str(&key_pool[i].addr));
return &key_pool[i];
}
}
for (i = 0; i < ARRAY_SIZE(key_pool); i++) {
if (!(key_pool[i].keys & BT_KEYS_IRK)) {
continue;
}
if (key_pool[i].id != id) {
continue;
}
if (bt_rpa_irk_matches(key_pool[i].irk.val, &addr->a)) {
LOG_DBG("RPA %s matches %s", bt_addr_str(&key_pool[i].irk.rpa),
bt_addr_le_str(&key_pool[i].addr));
bt_addr_copy(&key_pool[i].irk.rpa, &addr->a);
return &key_pool[i];
}
}
LOG_DBG("No IRK for %s", bt_addr_le_str(addr));
return NULL;
}
struct bt_keys *bt_keys_find_addr(uint8_t id, const bt_addr_le_t *addr)
{
int i;
__ASSERT_NO_MSG(addr != NULL);
LOG_DBG("%s", bt_addr_le_str(addr));
for (i = 0; i < ARRAY_SIZE(key_pool); i++) {
if (key_pool[i].id == id &&
bt_addr_le_eq(&key_pool[i].addr, addr)) {
return &key_pool[i];
}
}
return NULL;
}
void bt_keys_add_type(struct bt_keys *keys, enum bt_keys_type type)
{
__ASSERT_NO_MSG(keys != NULL);
keys->keys |= type;
}
void bt_keys_clear(struct bt_keys *keys)
{
__ASSERT_NO_MSG(keys != NULL);
LOG_DBG("%s (keys 0x%04x)", bt_addr_le_str(&keys->addr), keys->keys);
if (keys->state & BT_KEYS_ID_ADDED) {
bt_id_del(keys);
}
if (IS_ENABLED(CONFIG_BT_SETTINGS)) {
/* Delete stored keys from flash */
bt_settings_delete_keys(keys->id, &keys->addr);
}
(void)memset(keys, 0, sizeof(*keys));
}
#if defined(CONFIG_BT_SETTINGS)
int bt_keys_store(struct bt_keys *keys)
{
int err;
__ASSERT_NO_MSG(keys != NULL);
err = bt_settings_store_keys(keys->id, &keys->addr, keys->storage_start,
BT_KEYS_STORAGE_LEN);
if (err) {
LOG_ERR("Failed to save keys (err %d)", err);
return err;
}
LOG_DBG("Stored keys for %s", bt_addr_le_str(&keys->addr));
return 0;
}
static int keys_set(const char *name, size_t len_rd, settings_read_cb read_cb,
void *cb_arg)
{
struct bt_keys *keys;
bt_addr_le_t addr;
uint8_t id;
ssize_t len;
int err;
char val[BT_KEYS_STORAGE_LEN];
const char *next;
if (!name) {
LOG_ERR("Insufficient number of arguments");
return -EINVAL;
}
len = read_cb(cb_arg, val, sizeof(val));
if (len < 0) {
LOG_ERR("Failed to read value (err %zd)", len);
return -EINVAL;
}
LOG_DBG("name %s val %s", name, (len) ? bt_hex(val, sizeof(val)) : "(null)");
err = bt_settings_decode_key(name, &addr);
if (err) {
LOG_ERR("Unable to decode address %s", name);
return -EINVAL;
}
settings_name_next(name, &next);
if (!next) {
id = BT_ID_DEFAULT;
} else {
unsigned long next_id = strtoul(next, NULL, 10);
if (next_id >= CONFIG_BT_ID_MAX) {
LOG_ERR("Invalid local identity %lu", next_id);
return -EINVAL;
}
id = (uint8_t)next_id;
}
if (!len) {
keys = bt_keys_find(BT_KEYS_ALL, id, &addr);
if (keys) {
(void)memset(keys, 0, sizeof(*keys));
LOG_DBG("Cleared keys for %s", bt_addr_le_str(&addr));
} else {
LOG_WRN("Unable to find deleted keys for %s", bt_addr_le_str(&addr));
}
return 0;
}
keys = bt_keys_get_addr(id, &addr);
if (!keys) {
LOG_ERR("Failed to allocate keys for %s", bt_addr_le_str(&addr));
return -ENOMEM;
}
if (len != BT_KEYS_STORAGE_LEN) {
if (IS_ENABLED(CONFIG_BT_KEYS_OVERWRITE_OLDEST) &&
len == BT_KEYS_STORAGE_LEN_COMPAT) {
/* Load shorter structure for compatibility with old
* records format with no counter.
*/
LOG_WRN("Keys for %s have no aging counter", bt_addr_le_str(&addr));
memcpy(keys->storage_start, val, len);
} else {
LOG_ERR("Invalid key length %zd != %zu", len, BT_KEYS_STORAGE_LEN);
bt_keys_clear(keys);
return -EINVAL;
}
} else {
memcpy(keys->storage_start, val, len);
}
LOG_DBG("Successfully restored keys for %s", bt_addr_le_str(&addr));
#if defined(CONFIG_BT_KEYS_OVERWRITE_OLDEST)
if (aging_counter_val < keys->aging_counter) {
aging_counter_val = keys->aging_counter;
}
#endif /* CONFIG_BT_KEYS_OVERWRITE_OLDEST */
return 0;
}
static void id_add(struct bt_keys *keys, void *user_data)
{
__ASSERT_NO_MSG(keys != NULL);
bt_id_add(keys);
}
static int keys_commit(void)
{
/* We do this in commit() rather than add() since add() may get
* called multiple times for the same address, especially if
* the keys were already removed.
*/
if (IS_ENABLED(CONFIG_BT_CENTRAL) && IS_ENABLED(CONFIG_BT_PRIVACY)) {
bt_keys_foreach_type(BT_KEYS_ALL, id_add, NULL);
} else {
bt_keys_foreach_type(BT_KEYS_IRK, id_add, NULL);
}
return 0;
}
BT_SETTINGS_DEFINE(keys, "keys", keys_set, keys_commit);
#endif /* CONFIG_BT_SETTINGS */
#if defined(CONFIG_BT_KEYS_OVERWRITE_OLDEST)
void bt_keys_update_usage(uint8_t id, const bt_addr_le_t *addr)
{
__ASSERT_NO_MSG(addr != NULL);
struct bt_keys *keys = bt_keys_find_addr(id, addr);
if (!keys) {
return;
}
if (last_keys_updated == keys) {
return;
}
keys->aging_counter = ++aging_counter_val;
last_keys_updated = keys;
LOG_DBG("Aging counter for %s is set to %u", bt_addr_le_str(addr), keys->aging_counter);
if (IS_ENABLED(CONFIG_BT_KEYS_SAVE_AGING_COUNTER_ON_PAIRING)) {
bt_keys_store(keys);
}
}
#endif /* CONFIG_BT_KEYS_OVERWRITE_OLDEST */
#if defined(CONFIG_BT_LOG_SNIFFER_INFO)
void bt_keys_show_sniffer_info(struct bt_keys *keys, void *data)
{
uint8_t ltk[16];
__ASSERT_NO_MSG(keys != NULL);
if (keys->keys & BT_KEYS_LTK_P256) {
sys_memcpy_swap(ltk, keys->ltk.val, keys->enc_size);
LOG_INF("SC LTK: 0x%s", bt_hex(ltk, keys->enc_size));
}
#if !defined(CONFIG_BT_SMP_SC_PAIR_ONLY)
if (keys->keys & BT_KEYS_PERIPH_LTK) {
sys_memcpy_swap(ltk, keys->periph_ltk.val, keys->enc_size);
LOG_INF("Legacy LTK: 0x%s (peripheral)", bt_hex(ltk, keys->enc_size));
}
#endif /* !CONFIG_BT_SMP_SC_PAIR_ONLY */
if (keys->keys & BT_KEYS_LTK) {
sys_memcpy_swap(ltk, keys->ltk.val, keys->enc_size);
LOG_INF("Legacy LTK: 0x%s (central)", bt_hex(ltk, keys->enc_size));
}
}
#endif /* defined(CONFIG_BT_LOG_SNIFFER_INFO) */
#ifdef ZTEST_UNITTEST
struct bt_keys *bt_keys_get_key_pool(void)
{
return key_pool;
}
#if defined(CONFIG_BT_KEYS_OVERWRITE_OLDEST)
uint32_t bt_keys_get_aging_counter_val(void)
{
return aging_counter_val;
}
struct bt_keys *bt_keys_get_last_keys_updated(void)
{
return last_keys_updated;
}
#endif /* CONFIG_BT_KEYS_OVERWRITE_OLDEST */
#endif /* ZTEST_UNITTEST */
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