Bluetooth: Add support for storing the key size

In some cases it will be useful having the key size used for
encrypting the link. For example, some profiles may restrict
some operations depending on the key length.

The key size is stored in the key that is passed to userspace
using the pin_length field in the key structure.

For now this field is only valid for LE controllers. 3.0+HS
controllers define the Read Encryption Key Size command, this
field is intended for storing the value returned by that
command.

Signed-off-by: Vinicius Costa Gomes <vinicius.gomes@openbossa.org>
Signed-off-by: Gustavo F. Padovan <padovan@profusion.mobi>

include/net/bluetooth/hci_core.h

@@ -261,6 +261,7 @@ struct hci_conn {
 	__u8		sec_level;
 	__u8		pending_sec_level;
 	__u8		pin_length;
+	__u8		enc_key_size;
 	__u8		io_capability;
 	__u8		power_save;
 	__u16		disc_timeout;
@@ -556,7 +557,7 @@ struct link_key *hci_find_ltk(struct hci_dev *hdev, __le16 ediv, u8 rand[8]);
 struct link_key *hci_find_link_key_type(struct hci_dev *hdev,
 					bdaddr_t *bdaddr, u8 type);
 int hci_add_ltk(struct hci_dev *hdev, int new_key, bdaddr_t *bdaddr,
-					__le16 ediv, u8 rand[8], u8 ltk[16]);
+			u8 key_size, __le16 ediv, u8 rand[8], u8 ltk[16]);
 int hci_remove_link_key(struct hci_dev *hdev, bdaddr_t *bdaddr);
 
 int hci_remote_oob_data_clear(struct hci_dev *hdev);

net/bluetooth/hci_core.c

@@ -1149,7 +1149,7 @@ int hci_add_link_key(struct hci_dev *hdev, struct hci_conn *conn, int new_key,
 }
 
 int hci_add_ltk(struct hci_dev *hdev, int new_key, bdaddr_t *bdaddr,
-					__le16 ediv, u8 rand[8], u8 ltk[16])
+			u8 key_size, __le16 ediv, u8 rand[8], u8 ltk[16])
 {
 	struct link_key *key, *old_key;
 	struct key_master_id *id;
@@ -1174,6 +1174,7 @@ int hci_add_ltk(struct hci_dev *hdev, int new_key, bdaddr_t *bdaddr,
 	bacpy(&key->bdaddr, bdaddr);
 	memcpy(key->val, ltk, sizeof(key->val));
 	key->type = HCI_LK_SMP_LTK;
+	key->pin_len = key_size;
 
 	id = (void *) &key->data;
 	id->ediv = ediv;

net/bluetooth/hci_event.c

@@ -2876,6 +2876,7 @@ static inline void hci_le_ltk_request_evt(struct hci_dev *hdev,
 
 	memcpy(cp.ltk, ltk->val, sizeof(ltk->val));
 	cp.handle = cpu_to_le16(conn->handle);
+	conn->pin_length = ltk->pin_len;
 
 	hci_send_cmd(hdev, HCI_OP_LE_LTK_REPLY, sizeof(cp), &cp);
 

net/bluetooth/mgmt.c

@@ -956,8 +956,8 @@ static int load_keys(struct sock *sk, u16 index, unsigned char *data, u16 len)
 			if (key->dlen != sizeof(struct key_master_id))
 				continue;
 
-			hci_add_ltk(hdev, 0, &key->bdaddr, id->ediv,
-							id->rand, key->val);
+			hci_add_ltk(hdev, 0, &key->bdaddr, key->pin_len,
+						id->ediv, id->rand, key->val);
 
 			continue;
 		}

net/bluetooth/smp.c

@@ -401,6 +401,7 @@ static u8 smp_cmd_pairing_random(struct l2cap_conn *conn, struct sk_buff *skb)
 				SMP_MAX_ENC_KEY_SIZE - conn->smp_key_size);
 
 		hci_le_start_enc(hcon, ediv, rand, stk);
+		hcon->enc_key_size = conn->smp_key_size;
 	} else {
 		u8 stk[16], r[16], rand[8];
 		__le16 ediv;
@@ -417,7 +418,8 @@ static u8 smp_cmd_pairing_random(struct l2cap_conn *conn, struct sk_buff *skb)
 		memset(stk + conn->smp_key_size, 0,
 				SMP_MAX_ENC_KEY_SIZE - conn->smp_key_size);
 
-		hci_add_ltk(conn->hcon->hdev, 0, conn->dst, ediv, rand, stk);
+		hci_add_ltk(conn->hcon->hdev, 0, conn->dst, conn->smp_key_size,
+							ediv, rand, stk);
 	}
 
 	return 0;
@@ -487,6 +489,8 @@ int smp_conn_security(struct l2cap_conn *conn, __u8 sec_level)
 
 			hci_le_start_enc(hcon, master->ediv, master->rand,
 								key->val);
+			hcon->enc_key_size = key->pin_len;
+
 			goto done;
 		}
 
@@ -528,8 +532,8 @@ static int smp_cmd_master_ident(struct l2cap_conn *conn, struct sk_buff *skb)
 
 	skb_pull(skb, sizeof(*rp));
 
-	hci_add_ltk(conn->hcon->hdev, 1, conn->src, rp->ediv,
-						rp->rand, conn->tk);
+	hci_add_ltk(conn->hcon->hdev, 1, conn->src, conn->smp_key_size,
+						rp->ediv, rp->rand, conn->tk);
 
 	smp_distribute_keys(conn, 1);
 
@@ -654,8 +658,8 @@ int smp_distribute_keys(struct l2cap_conn *conn, __u8 force)
 
 		smp_send_cmd(conn, SMP_CMD_ENCRYPT_INFO, sizeof(enc), &enc);
 
-		hci_add_ltk(conn->hcon->hdev, 1, conn->dst, ediv,
-							ident.rand, enc.ltk);
+		hci_add_ltk(conn->hcon->hdev, 1, conn->dst, conn->smp_key_size,
+						ediv, ident.rand, enc.ltk);
 
 		ident.ediv = cpu_to_le16(ediv);