From: Johan Hedberg <johan.hedberg@xxxxxxxxx>
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: Johan Hedberg <johan.hedberg@xxxxxxxxx>
---
net/bluetooth/smp.c | 85 ++++++++++++++++++++++++++++++++++++++++++-----------
net/bluetooth/smp.h | 1 +
2 files changed, 69 insertions(+), 17 deletions(-)
diff --git a/net/bluetooth/smp.c b/net/bluetooth/smp.c
index 43faf2aea2ab..fae391f1871f 100644
--- a/net/bluetooth/smp.c
+++ b/net/bluetooth/smp.c
@@ -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.
*/
@@ -1130,20 +1147,31 @@ 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 (smp_h6(smp->tfm_cmac, smp->tk, tmp1, smp->link_key)) {
- kzfree(smp->link_key);
- smp->link_key = NULL;
- 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)) {
@@ -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 (smp_h6(smp->tfm_cmac, key->val, tmp2, smp->tk))
- return;
+ 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.
diff --git a/net/bluetooth/smp.h b/net/bluetooth/smp.h
index ffcc70b6b199..0ff6247eaa6c 100644
--- a/net/bluetooth/smp.h
+++ b/net/bluetooth/smp.h
@@ -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 {
--
2.9.3
--
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