From 8c1b235594fbab9a13240a1dac12ea9fd99b6440 Mon Sep 17 00:00:00 2001 From: Marcel Holtmann Date: Thu, 15 Jan 2009 21:58:04 +0100 Subject: Bluetooth: Add enhanced security model for Simple Pairing The current security model is based around the flags AUTH, ENCRYPT and SECURE. Starting with support for the Bluetooth 2.1 specification this is no longer sufficient. The different security levels are now defined as SDP, LOW, MEDIUM and SECURE. Previously it was possible to set each security independently, but this actually doesn't make a lot of sense. For Bluetooth the encryption depends on a previous successful authentication. Also you can only update your existing link key if you successfully created at least one before. And of course the update of link keys without having proper encryption in place is a security issue. The new security levels from the Bluetooth 2.1 specification are now used internally. All old settings are mapped to the new values and this way it ensures that old applications still work. The only limitation is that it is no longer possible to set authentication without also enabling encryption. No application should have done this anyway since this is actually a security issue. Without encryption the integrity of the authentication can't be guaranteed. As default for a new L2CAP or RFCOMM connection, the LOW security level is used. The only exception here are the service discovery sessions on PSM 1 where SDP level is used. To have similar security strength as with a Bluetooth 2.0 and before combination key, the MEDIUM level should be used. This is according to the Bluetooth specification. The MEDIUM level will not require any kind of man-in-the-middle (MITM) protection. Only the HIGH security level will require this. Signed-off-by: Marcel Holtmann --- net/bluetooth/hci_conn.c | 45 ++++++++++++++++++++++++++++++--------------- 1 file changed, 30 insertions(+), 15 deletions(-) (limited to 'net/bluetooth/hci_conn.c') diff --git a/net/bluetooth/hci_conn.c b/net/bluetooth/hci_conn.c index a4a789f24c8d..98f97a1e9bbb 100644 --- a/net/bluetooth/hci_conn.c +++ b/net/bluetooth/hci_conn.c @@ -325,7 +325,7 @@ EXPORT_SYMBOL(hci_get_route); /* Create SCO or ACL connection. * Device _must_ be locked */ -struct hci_conn *hci_connect(struct hci_dev *hdev, int type, bdaddr_t *dst, __u8 auth_type) +struct hci_conn *hci_connect(struct hci_dev *hdev, int type, bdaddr_t *dst, __u8 sec_level, __u8 auth_type) { struct hci_conn *acl; struct hci_conn *sco; @@ -340,6 +340,7 @@ struct hci_conn *hci_connect(struct hci_dev *hdev, int type, bdaddr_t *dst, __u8 hci_conn_hold(acl); if (acl->state == BT_OPEN || acl->state == BT_CLOSED) { + acl->sec_level = sec_level; acl->auth_type = auth_type; hci_acl_connect(acl); } @@ -385,16 +386,17 @@ int hci_conn_check_link_mode(struct hci_conn *conn) EXPORT_SYMBOL(hci_conn_check_link_mode); /* Authenticate remote device */ -int hci_conn_auth(struct hci_conn *conn) +static int hci_conn_auth(struct hci_conn *conn, __u8 sec_level) { BT_DBG("conn %p", conn); - if (conn->ssp_mode > 0 && conn->hdev->ssp_mode > 0) { - if (!(conn->auth_type & 0x01)) { - conn->auth_type |= 0x01; - conn->link_mode &= ~HCI_LM_AUTH; - } - } + if (sec_level > conn->sec_level) + conn->link_mode &= ~HCI_LM_AUTH; + + conn->sec_level = sec_level; + + if (sec_level == BT_SECURITY_HIGH) + conn->auth_type |= 0x01; if (conn->link_mode & HCI_LM_AUTH) return 1; @@ -405,31 +407,42 @@ int hci_conn_auth(struct hci_conn *conn) hci_send_cmd(conn->hdev, HCI_OP_AUTH_REQUESTED, sizeof(cp), &cp); } + return 0; } -EXPORT_SYMBOL(hci_conn_auth); -/* Enable encryption */ -int hci_conn_encrypt(struct hci_conn *conn) +/* Enable security */ +int hci_conn_security(struct hci_conn *conn, __u8 sec_level) { BT_DBG("conn %p", conn); + if (sec_level == BT_SECURITY_SDP) + return 1; + + if (sec_level == BT_SECURITY_LOW) { + if (conn->ssp_mode > 0 && conn->hdev->ssp_mode > 0) + return hci_conn_auth(conn, sec_level); + else + return 1; + } + if (conn->link_mode & HCI_LM_ENCRYPT) - return hci_conn_auth(conn); + return hci_conn_auth(conn, sec_level); if (test_and_set_bit(HCI_CONN_ENCRYPT_PEND, &conn->pend)) return 0; - if (hci_conn_auth(conn)) { + if (hci_conn_auth(conn, sec_level)) { struct hci_cp_set_conn_encrypt cp; cp.handle = cpu_to_le16(conn->handle); cp.encrypt = 1; hci_send_cmd(conn->hdev, HCI_OP_SET_CONN_ENCRYPT, sizeof(cp), &cp); } + return 0; } -EXPORT_SYMBOL(hci_conn_encrypt); +EXPORT_SYMBOL(hci_conn_security); /* Change link key */ int hci_conn_change_link_key(struct hci_conn *conn) @@ -442,12 +455,13 @@ int hci_conn_change_link_key(struct hci_conn *conn) hci_send_cmd(conn->hdev, HCI_OP_CHANGE_CONN_LINK_KEY, sizeof(cp), &cp); } + return 0; } EXPORT_SYMBOL(hci_conn_change_link_key); /* Switch role */ -int hci_conn_switch_role(struct hci_conn *conn, uint8_t role) +int hci_conn_switch_role(struct hci_conn *conn, __u8 role) { BT_DBG("conn %p", conn); @@ -460,6 +474,7 @@ int hci_conn_switch_role(struct hci_conn *conn, uint8_t role) cp.role = role; hci_send_cmd(conn->hdev, HCI_OP_SWITCH_ROLE, sizeof(cp), &cp); } + return 0; } EXPORT_SYMBOL(hci_conn_switch_role); -- cgit v1.2.3