Commit 7498ffbd authored by Joakim Andersson's avatar Joakim Andersson Committed by Anas Nashif
Browse files

Bluetooth: SMP: Add option to disallow unauthenticated re-pairing 

Disallows all unauthenticated pairing attempts made by the
peer where an unauthenticated bond already exists.
This would enable cases where an attacker could copy the peer device
address to connect and start an unauthenticated pairing procedure
to replace the existing bond. Now in order to create a new bond the old
bond has to be explicitly deleted with bt_unpair.

Added option to disable this rule in order to maintain backwards
compatibility in case this behavior is accepted.

Signed-off-by: default avatarJoakim Andersson <joakim.andersson@nordicsemi.no>
parent 2ae9e277

subsys/bluetooth/host/Kconfig

+11 −0
Changes for subsys/bluetooth/host/Kconfig: 11 added lines, 0 removed lines.
Original line number Diff line number Diff line
@@ -300,6 +300,17 @@ config BT_SMP_SC_ONLY 
	  Security Mode 1 Level 4 stands for authenticated LE Secure Connections

	  pairing with encryption. Enabling this option disables legacy pairing.



config BT_SMP_ALLOW_UNAUTH_OVERWRITE

	bool "Allow unauthenticated pairing for paired device"

	help

	  This option allows all unauthenticated pairing attempts made by the

	  peer where an unauthenticated bond already exists.

	  This would enable cases where an attacker could copy the peer device

	  address to connect and start an unauthenticated pairing procedure

	  to replace the existing bond. When this option is disabled in order

	  to create a new bond the old bond has to be explicitly deleted with

	  bt_unpair.



config BT_FIXED_PASSKEY

	bool "Use a fixed passkey for pairing"

	help

subsys/bluetooth/host/smp.c

+6 −0
Changes for subsys/bluetooth/host/smp.c: 6 added lines, 0 removed lines.
Original line number Diff line number Diff line
@@ -581,6 +581,12 @@ bool update_keys_check(struct bt_smp *smp) 
		return false;

	}



	if (!IS_ENABLED(CONFIG_BT_SMP_ALLOW_UNAUTH_OVERWRITE) &&

	    (!(conn->le.keys->flags & BT_KEYS_AUTHENTICATED)

	     && smp->method == JUST_WORKS)) {

		return false;

	}



	return true;

}

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