Bluetooth: SMP: Make public key handling more robust

Update code to handle other users of the public key generation APIs
by fetching the current public key at the beginning of each SMP
session. This is particularly important if someone creates the (rather
odd) combination of Mesh and SMP where Mesh will regenerate a new
key pair after provisioning.

Signed-off-by: Johan Hedberg <[email protected]>

Author: Johan Hedberg

subsys/bluetooth/host/smp.c

@@ -252,8 +252,7 @@ static struct bt_smp_br bt_smp_br_pool[CONFIG_BT_MAX_CONN];
 static struct bt_smp bt_smp_pool[CONFIG_BT_MAX_CONN];
 static bool bondable = IS_ENABLED(CONFIG_BT_BONDABLE);
 static bool sc_supported;
-static bool sc_local_pkey_valid;
-static u8_t sc_public_key[64];
+static const u8_t *sc_public_key;
 
 static u8_t get_io_capa(void)
 {
@@ -2267,6 +2266,8 @@ static int smp_init(struct bt_smp *smp)
 
 	atomic_set_bit(&smp->allowed_cmds, BT_SMP_CMD_PAIRING_FAIL);
 
+	sc_public_key = bt_pub_key_get();
+
 	return 0;
 }
 
@@ -2634,7 +2635,7 @@ static u8_t smp_pairing_rsp(struct bt_smp *smp, struct net_buf *buf)
 		return 0;
 	}
 
-	if (!sc_local_pkey_valid) {
+	if (!sc_public_key) {
 		atomic_set_bit(smp->flags, SMP_FLAG_PKEY_SEND);
 		return 0;
 	}
@@ -3401,7 +3402,7 @@ static u8_t smp_public_key(struct bt_smp *smp, struct net_buf *buf)
 	}
 
 #if defined(CONFIG_BT_PERIPHERAL)
-	if (!sc_local_pkey_valid) {
+	if (!sc_public_key) {
 		atomic_set_bit(smp->flags, SMP_FLAG_PKEY_SEND);
 		return 0;
 	}
@@ -3569,15 +3570,13 @@ static void bt_smp_pkey_ready(const u8_t *pkey)
 
 	BT_DBG("");
 
+	sc_public_key = pkey;
+
 	if (!pkey) {
 		BT_WARN("Public key not available");
-		sc_local_pkey_valid = false;
 		return;
 	}
 
-	memcpy(sc_public_key, pkey, 64);
-	sc_local_pkey_valid = true;
-
 	for (i = 0; i < ARRAY_SIZE(bt_smp_pool); i++) {
 		struct bt_smp *smp = &bt_smp_pool[i];
 		u8_t err;
@@ -4387,7 +4386,7 @@ int bt_smp_auth_pairing_confirm(struct bt_conn *conn)
 			return legacy_send_pairing_confirm(smp);
 		}
 
-		if (!sc_local_pkey_valid) {
+		if (!sc_public_key) {
 			atomic_set_bit(smp->flags, SMP_FLAG_PKEY_SEND);
 			return 0;
 		}