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From:   Luiz Augusto von Dentz <luiz.dentz@gmail.com>
To:     linux-bluetooth@vger.kernel.org
Subject: [PATCH v2 1/2] Bluetooth: SMP: Fail if remote and local public keys are identical
Date:   Wed, 10 Mar 2021 14:13:08 -0800
Message-Id: <20210310221309.894602-1-luiz.dentz@gmail.com>
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From: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>

This fails the pairing procedure when both remote and local non-debug
public keys are identical.

Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>
---
v2: Use crypto_memneq instead of memcmp and add a patch converting the use of
BT_ERR/BT_DBG to bt_dev_err/bt_dev_dbg.

 net/bluetooth/smp.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/net/bluetooth/smp.c b/net/bluetooth/smp.c
index b0c1ee110eff..e03cc284161c 100644
--- a/net/bluetooth/smp.c
+++ b/net/bluetooth/smp.c
@@ -2732,6 +2732,15 @@ static int smp_cmd_public_key(struct l2cap_conn *conn, struct sk_buff *skb)
 	if (skb->len < sizeof(*key))
 		return SMP_INVALID_PARAMS;
 
+	/* Check if remote and local public keys are the same and debug key is
+	 * not in use.
+	 */
+	if (!test_bit(SMP_FLAG_DEBUG_KEY, &smp->flags) &&
+	    !crypto_memneq(key, smp->local_pk, 64)) {
+		bt_dev_err(hdev, "Remote and local public keys are identical");
+		return SMP_UNSPECIFIED;
+	}
+
 	memcpy(smp->remote_pk, key, 64);
 
 	if (test_bit(SMP_FLAG_REMOTE_OOB, &smp->flags)) {
-- 
2.29.2