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Commit a62da6f1 authored by Johan Hedberg's avatar Johan Hedberg Committed by Marcel Holtmann
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Bluetooth: SMP: Add support for H7 crypto function and CT2 auth flag 



Bluetooth 5.0 introduces a new H7 key generation function that's used
when both sides of the pairing set the CT2 authentication flag to 1.

Signed-off-by: default avatarJohan Hedberg <johan.hedberg@intel.com>
Signed-off-by: default avatarMarcel Holtmann <marcel@holtmann.org>
parent 0705f7b1

net/bluetooth/smp.c

+68 −17
Original line number Diff line number Diff line
@@ -57,7 +57,7 @@ 
#define SMP_TIMEOUT	msecs_to_jiffies(30000)



#define AUTH_REQ_MASK(dev)	(hci_dev_test_flag(dev, HCI_SC_ENABLED) ? \

				 0x1f : 0x07)

				 0x3f : 0x07)

#define KEY_DIST_MASK		0x07



/* Maximum message length that can be passed to aes_cmac */
@@ -76,6 +76,7 @@ enum { 
	SMP_FLAG_DHKEY_PENDING,

	SMP_FLAG_REMOTE_OOB,

	SMP_FLAG_LOCAL_OOB,

	SMP_FLAG_CT2,

};



struct smp_dev {
@@ -357,6 +358,22 @@ static int smp_h6(struct crypto_shash *tfm_cmac, const u8 w[16], 
	return err;

}



static int smp_h7(struct crypto_shash *tfm_cmac, const u8 w[16],

		  const u8 salt[16], u8 res[16])

{

	int err;



	SMP_DBG("w %16phN salt %16phN", w, salt);



	err = aes_cmac(tfm_cmac, salt, w, 16, res);

	if (err)

		return err;



	SMP_DBG("res %16phN", res);



	return err;

}



/* The following functions map to the legacy SMP crypto functions e, c1,

 * s1 and ah.

 */
@@ -1130,21 +1147,32 @@ static void sc_add_ltk(struct smp_chan *smp) 


static void sc_generate_link_key(struct smp_chan *smp)

{

	/* These constants are as specified in the core specification.

	 * In ASCII they spell out to 'tmp1' and 'lebr'.

	 */

	const u8 tmp1[4] = { 0x31, 0x70, 0x6d, 0x74 };

	/* From core spec. Spells out in ASCII as 'lebr'. */

	const u8 lebr[4] = { 0x72, 0x62, 0x65, 0x6c };



	smp->link_key = kzalloc(16, GFP_KERNEL);

	if (!smp->link_key)

		return;



	if (test_bit(SMP_FLAG_CT2, &smp->flags)) {

		/* SALT = 0x00000000000000000000000000000000746D7031 */

		const u8 salt[16] = { 0x31, 0x70, 0x6d, 0x74 };



		if (smp_h7(smp->tfm_cmac, smp->tk, salt, smp->link_key)) {

			kzfree(smp->link_key);

			smp->link_key = NULL;

			return;

		}

	} else {

		/* From core spec. Spells out in ASCII as 'tmp1'. */

		const u8 tmp1[4] = { 0x31, 0x70, 0x6d, 0x74 };



		if (smp_h6(smp->tfm_cmac, smp->tk, tmp1, smp->link_key)) {

			kzfree(smp->link_key);

			smp->link_key = NULL;

			return;

		}

	}



	if (smp_h6(smp->tfm_cmac, smp->link_key, lebr, smp->link_key)) {

		kzfree(smp->link_key);
@@ -1169,10 +1197,7 @@ static void smp_allow_key_dist(struct smp_chan *smp) 


static void sc_generate_ltk(struct smp_chan *smp)

{

	/* These constants are as specified in the core specification.

	 * In ASCII they spell out to 'tmp2' and 'brle'.

	 */

	const u8 tmp2[4] = { 0x32, 0x70, 0x6d, 0x74 };

	/* From core spec. Spells out in ASCII as 'brle'. */

	const u8 brle[4] = { 0x65, 0x6c, 0x72, 0x62 };

	struct hci_conn *hcon = smp->conn->hcon;

	struct hci_dev *hdev = hcon->hdev;
@@ -1187,8 +1212,19 @@ static void sc_generate_ltk(struct smp_chan *smp) 
	if (key->type == HCI_LK_DEBUG_COMBINATION)

		set_bit(SMP_FLAG_DEBUG_KEY, &smp->flags);



	if (test_bit(SMP_FLAG_CT2, &smp->flags)) {

		/* SALT = 0x00000000000000000000000000000000746D7032 */

		const u8 salt[16] = { 0x32, 0x70, 0x6d, 0x74 };



		if (smp_h7(smp->tfm_cmac, key->val, salt, smp->tk))

			return;

	} else {

		/* From core spec. Spells out in ASCII as 'tmp2'. */

		const u8 tmp2[4] = { 0x32, 0x70, 0x6d, 0x74 };



		if (smp_h6(smp->tfm_cmac, key->val, tmp2, smp->tk))

			return;

	}



	if (smp_h6(smp->tfm_cmac, smp->tk, brle, smp->tk))

		return;
@@ -1669,6 +1705,7 @@ static void build_bredr_pairing_cmd(struct smp_chan *smp, 
	if (!rsp) {

		memset(req, 0, sizeof(*req));



		req->auth_req        = SMP_AUTH_CT2;

		req->init_key_dist   = local_dist;

		req->resp_key_dist   = remote_dist;

		req->max_key_size    = conn->hcon->enc_key_size;
@@ -1680,6 +1717,7 @@ static void build_bredr_pairing_cmd(struct smp_chan *smp, 


	memset(rsp, 0, sizeof(*rsp));



	rsp->auth_req        = SMP_AUTH_CT2;

	rsp->max_key_size    = conn->hcon->enc_key_size;

	rsp->init_key_dist   = req->init_key_dist & remote_dist;

	rsp->resp_key_dist   = req->resp_key_dist & local_dist;
@@ -1744,6 +1782,9 @@ static u8 smp_cmd_pairing_req(struct l2cap_conn *conn, struct sk_buff *skb) 


		build_bredr_pairing_cmd(smp, req, &rsp);



		if (req->auth_req & SMP_AUTH_CT2)

			set_bit(SMP_FLAG_CT2, &smp->flags);



		key_size = min(req->max_key_size, rsp.max_key_size);

		if (check_enc_key_size(conn, key_size))

			return SMP_ENC_KEY_SIZE;
@@ -1761,9 +1802,13 @@ static u8 smp_cmd_pairing_req(struct l2cap_conn *conn, struct sk_buff *skb) 


	build_pairing_cmd(conn, req, &rsp, auth);



	if (rsp.auth_req & SMP_AUTH_SC)

	if (rsp.auth_req & SMP_AUTH_SC) {

		set_bit(SMP_FLAG_SC, &smp->flags);



		if (rsp.auth_req & SMP_AUTH_CT2)

			set_bit(SMP_FLAG_CT2, &smp->flags);

	}



	if (conn->hcon->io_capability == HCI_IO_NO_INPUT_OUTPUT)

		sec_level = BT_SECURITY_MEDIUM;

	else
@@ -1917,6 +1962,9 @@ static u8 smp_cmd_pairing_rsp(struct l2cap_conn *conn, struct sk_buff *skb) 
	 */

	smp->remote_key_dist &= rsp->resp_key_dist;



	if ((req->auth_req & SMP_AUTH_CT2) && (auth & SMP_AUTH_CT2))

		set_bit(SMP_FLAG_CT2, &smp->flags);



	/* For BR/EDR this means we're done and can start phase 3 */

	if (conn->hcon->type == ACL_LINK) {

		/* Clear bits which are generated but not distributed */
@@ -2312,8 +2360,11 @@ int smp_conn_security(struct hci_conn *hcon, __u8 sec_level) 


	authreq = seclevel_to_authreq(sec_level);



	if (hci_dev_test_flag(hcon->hdev, HCI_SC_ENABLED))

	if (hci_dev_test_flag(hcon->hdev, HCI_SC_ENABLED)) {

		authreq |= SMP_AUTH_SC;

		if (hci_dev_test_flag(hcon->hdev, HCI_SSP_ENABLED))

			authreq |= SMP_AUTH_CT2;

	}



	/* Require MITM if IO Capability allows or the security level

	 * requires it.

net/bluetooth/smp.h

+1 −0
Original line number Diff line number Diff line
@@ -57,6 +57,7 @@ struct smp_cmd_pairing { 
#define SMP_AUTH_MITM		0x04

#define SMP_AUTH_SC		0x08

#define SMP_AUTH_KEYPRESS	0x10

#define SMP_AUTH_CT2		0x20



#define SMP_CMD_PAIRING_CONFIRM	0x03

struct smp_cmd_pairing_confirm {