Bluetooth: Add support for persistent pairing keys storage
Integrate the bt_keys submodule with bt_settings. Add a new bt_keys_store() API to write keys to flash, and extend the existing bt_keys_clear() to remove the keys from flash. Along with this, add some helpers for genrating settings key values containing a bluetooth address, as well as for decoding them to get the binary bt_addr_le_t. Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>
This commit is contained in:
Johan Hedberg
Anas Nashif
parent
470349c25a
commit
f36ea83628
6 changed files with 228 additions and 20 deletions
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@ -133,7 +133,7 @@ config BT_HOST_CRYPTO
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config BT_SETTINGS
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bool "Store Bluetooth state and configuration persistently"
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depends on SETTINGS
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depends on SETTINGS && PRINTK
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select MPU_ALLOW_FLASH_WRITE if ARM_MPU
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help
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When selected, the Bluetooth stack will take care of storing
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@ -11,6 +11,8 @@
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#include <atomic.h>
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#include <misc/util.h>
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#include <settings/settings.h>
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#include <bluetooth/bluetooth.h>
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#include <bluetooth/conn.h>
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#include <bluetooth/hci.h>
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@ -21,6 +23,7 @@
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#include "common/rpa.h"
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#include "hci_core.h"
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#include "smp.h"
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#include "settings.h"
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#include "keys.h"
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static struct bt_keys key_pool[CONFIG_BT_MAX_PAIRED];
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@ -165,12 +168,22 @@ void bt_keys_add_type(struct bt_keys *keys, int type)
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void bt_keys_clear(struct bt_keys *keys)
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{
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BT_DBG("keys for %s", bt_addr_le_str(&keys->addr));
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BT_DBG("%s (keys 0x%04x)", bt_addr_le_str(&keys->addr), keys->keys);
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if (keys->keys & BT_KEYS_IRK) {
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bt_id_del(keys);
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}
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if (IS_ENABLED(CONFIG_BT_SETTINGS)) {
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char key[BT_SETTINGS_KEY_MAX];
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/* Delete stored keys from flash */
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bt_settings_encode_key(key, sizeof(key), "keys", &keys->addr,
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NULL);
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BT_DBG("Deleting key %s", key);
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settings_save_one(key, NULL);
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}
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memset(keys, 0, sizeof(*keys));
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}
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@ -178,3 +191,103 @@ void bt_keys_clear_all(void)
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{
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bt_keys_foreach(BT_KEYS_ALL, bt_keys_clear);
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}
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#if defined(CONFIG_BT_SETTINGS)
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int bt_keys_store(struct bt_keys *keys)
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{
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char val[BT_SETTINGS_SIZE(BT_KEYS_STORAGE_LEN)];
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char key[BT_SETTINGS_KEY_MAX];
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char *str;
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int err;
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str = settings_str_from_bytes(keys->storage_start, BT_KEYS_STORAGE_LEN,
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val, sizeof(val));
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if (!str) {
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BT_ERR("Unable to encode bt_keys as value");
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return -EINVAL;
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}
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bt_settings_encode_key(key, sizeof(key), "keys", &keys->addr, NULL);
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err = settings_save_one(key, val);
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if (err) {
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BT_ERR("Failed to save keys (err %d)", err);
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return err;
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}
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BT_DBG("Stored keys for %s (%s)", bt_addr_le_str(&keys->addr), key);
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return 0;
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}
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static int keys_set(int argc, char **argv, char *val)
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{
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struct bt_keys *keys;
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bt_addr_le_t addr;
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int len, err;
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if (argc < 1) {
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BT_ERR("Insufficient number of arguments");
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return -EINVAL;
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}
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BT_DBG("argv[0] %s val %s", argv[0], val ? val : "(null)");
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err = bt_settings_decode_key(argv[0], &addr);
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if (err) {
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BT_ERR("Unable to decode address %s", argv[0]);
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return -EINVAL;
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}
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if (!val) {
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keys = bt_keys_find(BT_KEYS_ALL, &addr);
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if (keys) {
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memset(keys, 0, sizeof(*keys));
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BT_DBG("Cleared keys for %s", bt_addr_le_str(&addr));
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} else {
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BT_WARN("Unable to find deleted keys for %s",
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bt_addr_le_str(&addr));
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}
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return 0;
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}
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keys = bt_keys_get_addr(&addr);
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if (!keys) {
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BT_ERR("Failed to allocate keys for %s", bt_addr_le_str(&addr));
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return -ENOMEM;
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}
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len = BT_KEYS_STORAGE_LEN;
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err = settings_bytes_from_str(val, keys->storage_start, &len);
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if (err) {
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BT_ERR("Failed to decode value (err %d)", err);
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bt_keys_clear(keys);
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return err;
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}
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if (len != BT_KEYS_STORAGE_LEN) {
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BT_ERR("Invalid key length %d != %d", len, BT_KEYS_STORAGE_LEN);
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bt_keys_clear(keys);
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return -EINVAL;
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}
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BT_DBG("Successfully restored keys for %s", bt_addr_le_str(&addr));
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return 0;
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}
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static int keys_commit(void)
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{
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BT_DBG("");
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/* We do this in commit() rather than add() since add() may get
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* called multiple times for the same address, especially if
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* the keys were already removed.
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*/
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bt_keys_foreach(BT_KEYS_IRK, (bt_keys_func_t)bt_id_add);
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return 0;
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}
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BT_SETTINGS_DEFINE(keys, keys_set, keys_commit, NULL);
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#endif /* CONFIG_BT_SETTINGS */
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@ -47,6 +47,7 @@ struct bt_csrk {
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struct bt_keys {
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bt_addr_le_t addr;
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u8_t storage_start[0];
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u8_t enc_size;
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ATOMIC_DEFINE(flags, BT_KEYS_NUM_FLAGS);
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u16_t keys;
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@ -61,7 +62,11 @@ struct bt_keys {
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#endif /* CONFIG_BT_SMP_SC_ONLY */
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};
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void bt_keys_foreach(int type, void (*func)(struct bt_keys *keys));
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#define BT_KEYS_STORAGE_LEN (sizeof(struct bt_keys) - \
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offsetof(struct bt_keys, storage_start))
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typedef void (*bt_keys_func_t)(struct bt_keys *keys);
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void bt_keys_foreach(int type, bt_keys_func_t func);
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struct bt_keys *bt_keys_get_addr(const bt_addr_le_t *addr);
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struct bt_keys *bt_keys_get_type(int type, const bt_addr_le_t *addr);
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@ -73,6 +78,15 @@ void bt_keys_add_type(struct bt_keys *keys, int type);
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void bt_keys_clear(struct bt_keys *keys);
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void bt_keys_clear_all(void);
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#if defined(CONFIG_BT_SETTINGS)
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int bt_keys_store(struct bt_keys *keys);
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#else
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static inline int bt_keys_store(struct bt_keys *keys)
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{
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return 0;
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}
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#endif
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enum {
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BT_LINK_KEY_AUTHENTICATED,
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BT_LINK_KEY_DEBUG,
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@ -22,11 +22,75 @@
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extern const struct bt_settings_handler _bt_settings_start[];
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extern const struct bt_settings_handler _bt_settings_end[];
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void bt_settings_encode_key(char *path, size_t path_size, const char *subsys,
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bt_addr_le_t *addr, const char *key)
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{
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if (key) {
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snprintk(path, path_size,
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"bt/%s/%02x%02x%02x%02x%02x%02x%u/%s", subsys,
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addr->a.val[5], addr->a.val[4], addr->a.val[3],
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addr->a.val[2], addr->a.val[1], addr->a.val[0],
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addr->type, key);
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} else {
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snprintk(path, path_size,
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"bt/%s/%02x%02x%02x%02x%02x%02x%u", subsys,
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addr->a.val[5], addr->a.val[4], addr->a.val[3],
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addr->a.val[2], addr->a.val[1], addr->a.val[0],
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addr->type);
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}
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BT_DBG("Encoded path %s", path);
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}
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int bt_settings_decode_key(char *key, bt_addr_le_t *addr)
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{
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bool high;
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int i;
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if (strlen(key) != 13) {
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return -EINVAL;
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}
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if (key[12] == '0') {
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addr->type = BT_ADDR_LE_PUBLIC;
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} else if (key[12] == '1') {
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addr->type = BT_ADDR_LE_RANDOM;
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} else {
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return -EINVAL;
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}
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for (i = 5, high = true; i >= 0; key++) {
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u8_t nibble;
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if (*key >= '0' && *key <= '9') {
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nibble = *key - '0';
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} else if (*key >= 'a' && *key <= 'f') {
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nibble = *key - 'a' + 10;
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} else {
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return -EINVAL;
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}
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if (high) {
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addr->a.val[i] = nibble << 4;
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high = false;
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} else {
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addr->a.val[i] |= nibble;
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high = true;
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i--;
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}
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}
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BT_DBG("Decoded %s as %s", key, bt_addr_le_str(addr));
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return 0;
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}
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static int set(int argc, char **argv, char *val)
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{
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int len;
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BT_DBG("argc %d argv[0] %s val %s", argc, argv[0], val);
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BT_DBG("argc %d argv[0] %s argv[1] %s val %s", argc, argv[0],
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argc > 1 ? argv[1] : "(null)", val ? val : "(null)");
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if (argc > 1) {
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const struct bt_settings_handler *h;
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@ -64,7 +128,7 @@ static int set(int argc, char **argv, char *val)
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static void generate_static_addr(void)
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{
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char buf[13];
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char buf[BT_SETTINGS_SIZE(sizeof(bt_dev.id_addr))];
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char *str;
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BT_DBG("Generating new static random address");
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@ -92,7 +156,7 @@ static void generate_static_addr(void)
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#if defined(CONFIG_BT_PRIVACY)
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static void generate_irk(void)
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{
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char buf[25];
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char buf[BT_SETTINGS_SIZE(sizeof(bt_dev.irk))];
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char *str;
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BT_DBG("Generating new IRK");
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@ -20,4 +20,15 @@ struct bt_settings_handler {
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.export = _export, \
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}
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/* Max settings key length (with all components) */
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#define BT_SETTINGS_KEY_MAX 36
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/* Base64-encoded string buffer size of in_size bytes */
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#define BT_SETTINGS_SIZE(in_size) ((((((in_size) - 1) / 3) * 4) + 4) + 1)
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/* Helpers for keys containing a bdaddr */
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void bt_settings_encode_key(char *path, size_t path_size, const char *subsys,
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bt_addr_le_t *addr, const char *key);
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int bt_settings_decode_key(char *key, bt_addr_le_t *addr);
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int bt_settings_init(void);
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@ -694,24 +694,27 @@ static void smp_br_reset(struct bt_smp_br *smp)
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static void smp_pairing_br_complete(struct bt_smp_br *smp, u8_t status)
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{
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struct bt_conn *conn = smp->chan.chan.conn;
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struct bt_keys *keys;
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bt_addr_le_t addr;
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BT_DBG("status 0x%x", status);
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/* For dualmode devices LE address is same as BR/EDR address
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* and is of public type.
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*/
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bt_addr_copy(&addr.a, &conn->br.dst);
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addr.type = BT_ADDR_LE_PUBLIC;
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keys = bt_keys_find_addr(&addr);
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if (status) {
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struct bt_conn *conn = smp->chan.chan.conn;
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struct bt_keys *keys;
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bt_addr_le_t addr;
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/*
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* For dualmode devices LE address is same as BR/EDR address
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* and is of public type.
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*/
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bt_addr_copy(&addr.a, &conn->br.dst);
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addr.type = BT_ADDR_LE_PUBLIC;
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keys = bt_keys_find_addr(&addr);
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if (keys) {
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bt_keys_clear(keys);
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}
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} else if (atomic_test_bit(smp->flags, SMP_FLAG_BOND)) {
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if (keys) {
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bt_keys_store(keys);
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}
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}
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smp_br_reset(smp);
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@ -1469,8 +1472,8 @@ static void smp_pairing_complete(struct bt_smp *smp, u8_t status)
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{
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BT_DBG("status 0x%x", status);
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#if defined(CONFIG_BT_BREDR)
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if (!status) {
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#if defined(CONFIG_BT_BREDR)
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/*
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* Don't derive if Debug Keys are used.
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* TODO should we allow this if BR/EDR is already connected?
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@ -1479,8 +1482,11 @@ static void smp_pairing_complete(struct bt_smp *smp, u8_t status)
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!atomic_test_bit(smp->flags, SMP_FLAG_SC_DEBUG_KEY)) {
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sc_derive_link_key(smp);
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}
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}
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#endif /* CONFIG_BT_BREDR */
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if (atomic_test_bit(smp->flags, SMP_FLAG_BOND)) {
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bt_keys_store(smp->chan.chan.conn->le.keys);
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}
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}
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smp_reset(smp);
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}
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