From: Oleh Konko <security@1seal.org> stable inclusion from stable-v5.10.253 commit 425a22c5373d4e1b46492ab869074ebeeade61f3 category: bugfix bugzilla: 189268 Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=... -------------------------------- commit d05111bfe37bfd8bd4d2dfe6675d6bdeef43f7c7 upstream. smp_cmd_pairing_req() currently builds the pairing response from the initiator auth_req before enforcing the local BT_SECURITY_HIGH requirement. If the initiator omits SMP_AUTH_MITM, the response can also omit it even though the local side still requires MITM. tk_request() then sees an auth value without SMP_AUTH_MITM and may select JUST_CFM, making method selection inconsistent with the pairing policy the responder already enforces. When the local side requires HIGH security, first verify that MITM can be achieved from the IO capabilities and then force SMP_AUTH_MITM in the response in both rsp.auth_req and auth. This keeps the responder auth bits and later method selection aligned. Fixes: 2b64d153a0cc ("Bluetooth: Add MITM mechanism to LE-SMP") Cc: stable@vger.kernel.org Suggested-by: Luiz Augusto von Dentz <luiz.dentz@gmail.com> Signed-off-by: Oleh Konko <security@1seal.org> Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Lin Yujun <linyujun809@h-partners.com> Signed-off-by: Xinyu Zheng <zhengxinyu6@huawei.com> --- net/bluetooth/smp.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/net/bluetooth/smp.c b/net/bluetooth/smp.c index d9a378d12be6..4655534b6cc1 100644 --- a/net/bluetooth/smp.c +++ b/net/bluetooth/smp.c @@ -1828,7 +1828,7 @@ static u8 smp_cmd_pairing_req(struct l2cap_conn *conn, struct sk_buff *skb) if (sec_level > conn->hcon->pending_sec_level) conn->hcon->pending_sec_level = sec_level; - /* If we need MITM check that it can be achieved */ + /* If we need MITM check that it can be achieved. */ if (conn->hcon->pending_sec_level >= BT_SECURITY_HIGH) { u8 method; @@ -1836,6 +1836,10 @@ static u8 smp_cmd_pairing_req(struct l2cap_conn *conn, struct sk_buff *skb) req->io_capability); if (method == JUST_WORKS || method == JUST_CFM) return SMP_AUTH_REQUIREMENTS; + + /* Force MITM bit if it isn't set by the initiator. */ + auth |= SMP_AUTH_MITM; + rsp.auth_req |= SMP_AUTH_MITM; } key_size = min(req->max_key_size, rsp.max_key_size); -- 2.34.1