6.1-stable review patch. If anyone has any objections, please let me know.
------------------
From: Luiz Augusto von Dentz luiz.von.dentz@intel.com
[ Upstream commit 545d7827b2cd5de5eb85580cebeda6b35b3ff443 ]
The change eed467b517e8 ("Bluetooth: fix passkey uninitialized when used") introduced a goto that bypasses the creation of temporary mackey and ltk which are later used by the likes of DHKey Check step.
Later ffee202a78c2 ("Bluetooth: Always request for user confirmation for Just Works (LE SC)") which means confirm_hint is always set in case JUST_WORKS so the branch checking for an existing LTK becomes pointless as confirm_hint will always be set, so this just merge both cases of malicious or legitimate devices to be confirmed before continuing with the pairing procedure.
Link: https://github.com/bluez/bluez/issues/1622 Fixes: eed467b517e8 ("Bluetooth: fix passkey uninitialized when used") Signed-off-by: Luiz Augusto von Dentz luiz.von.dentz@intel.com Signed-off-by: Sasha Levin sashal@kernel.org --- net/bluetooth/smp.c | 31 +++++++------------------------ 1 file changed, 7 insertions(+), 24 deletions(-)
diff --git a/net/bluetooth/smp.c b/net/bluetooth/smp.c index a03920fe44d94..d8a77bfe65a62 100644 --- a/net/bluetooth/smp.c +++ b/net/bluetooth/smp.c @@ -2130,7 +2130,7 @@ static u8 smp_cmd_pairing_random(struct l2cap_conn *conn, struct sk_buff *skb) struct smp_chan *smp = chan->data; struct hci_conn *hcon = conn->hcon; u8 *pkax, *pkbx, *na, *nb, confirm_hint; - u32 passkey; + u32 passkey = 0; int err;
bt_dev_dbg(hcon->hdev, "conn %p", conn); @@ -2182,24 +2182,6 @@ static u8 smp_cmd_pairing_random(struct l2cap_conn *conn, struct sk_buff *skb) smp_send_cmd(conn, SMP_CMD_PAIRING_RANDOM, sizeof(smp->prnd), smp->prnd); SMP_ALLOW_CMD(smp, SMP_CMD_DHKEY_CHECK); - - /* Only Just-Works pairing requires extra checks */ - if (smp->method != JUST_WORKS) - goto mackey_and_ltk; - - /* If there already exists long term key in local host, leave - * the decision to user space since the remote device could - * be legitimate or malicious. - */ - if (hci_find_ltk(hcon->hdev, &hcon->dst, hcon->dst_type, - hcon->role)) { - /* Set passkey to 0. The value can be any number since - * it'll be ignored anyway. - */ - passkey = 0; - confirm_hint = 1; - goto confirm; - } }
mackey_and_ltk: @@ -2220,11 +2202,12 @@ static u8 smp_cmd_pairing_random(struct l2cap_conn *conn, struct sk_buff *skb) if (err) return SMP_UNSPECIFIED;
- confirm_hint = 0; - -confirm: - if (smp->method == JUST_WORKS) - confirm_hint = 1; + /* Always require user confirmation for Just-Works pairing to prevent + * impersonation attacks, or in case of a legitimate device that is + * repairing use the confirmation as acknowledgment to proceed with the + * creation of new keys. + */ + confirm_hint = smp->method == JUST_WORKS ? 1 : 0;
err = mgmt_user_confirm_request(hcon->hdev, &hcon->dst, hcon->type, hcon->dst_type, passkey, confirm_hint);