From: Johan Hedberg <johan.hedberg@xxxxxxxxx>
This patch adds code to select the authentication method for Secure
Connections based on the local and remote capabilities. A new
DSP_PASSKEY method is also added for displaying the passkey - something
that is not part of legacy SMP pairing.
Signed-off-by: Johan Hedberg <johan.hedberg@xxxxxxxxx>
---
net/bluetooth/smp.c | 74 +++++++++++++++++++++++++++++++++++++++++++++++++----
1 file changed, 69 insertions(+), 5 deletions(-)
diff --git a/net/bluetooth/smp.c b/net/bluetooth/smp.c
index 651963f26da0..8753d8120850 100644
--- a/net/bluetooth/smp.c
+++ b/net/bluetooth/smp.c
@@ -661,6 +661,7 @@ static void smp_failure(struct l2cap_conn *conn, u8 reason)
#define REQ_PASSKEY 0x02
#define CFM_PASSKEY 0x03
#define REQ_OOB 0x04
+#define DSP_PASSKEY 0x05
#define OVERLAP 0xFF
static const u8 gen_method[5][5] = {
@@ -671,6 +672,14 @@ static const u8 gen_method[5][5] = {
{ CFM_PASSKEY, CFM_PASSKEY, REQ_PASSKEY, JUST_WORKS, OVERLAP },
};
+static const u8 sc_method[5][5] = {
+ { JUST_WORKS, JUST_CFM, REQ_PASSKEY, JUST_WORKS, REQ_PASSKEY },
+ { JUST_WORKS, CFM_PASSKEY, REQ_PASSKEY, JUST_WORKS, CFM_PASSKEY },
+ { DSP_PASSKEY, DSP_PASSKEY, REQ_PASSKEY, JUST_WORKS, DSP_PASSKEY },
+ { JUST_WORKS, JUST_CFM, JUST_WORKS, JUST_WORKS, JUST_CFM },
+ { DSP_PASSKEY, CFM_PASSKEY, REQ_PASSKEY, JUST_WORKS, CFM_PASSKEY },
+};
+
static u8 get_auth_method(struct smp_chan *smp, u8 local_io, u8 remote_io)
{
/* If either side has unknown io_caps, use JUST_CFM (which gets
@@ -680,6 +689,9 @@ static u8 get_auth_method(struct smp_chan *smp, u8 local_io, u8 remote_io)
remote_io > SMP_IO_KEYBOARD_DISPLAY)
return JUST_CFM;
+ if (test_bit(SMP_FLAG_SC, &smp->flags))
+ return sc_method[remote_io][local_io];
+
return gen_method[remote_io][local_io];
}
@@ -1305,6 +1317,11 @@ static u8 smp_cmd_pairing_req(struct l2cap_conn *conn, struct sk_buff *skb)
memcpy(&smp->preq[1], req, sizeof(*req));
skb_pull(skb, sizeof(*req));
+ build_pairing_cmd(conn, req, &rsp, auth);
+
+ if (rsp.auth_req & SMP_AUTH_SC)
+ set_bit(SMP_FLAG_SC, &smp->flags);
+
if (conn->hcon->io_capability == HCI_IO_NO_INPUT_OUTPUT)
sec_level = BT_SECURITY_MEDIUM;
else
@@ -1323,11 +1340,6 @@ static u8 smp_cmd_pairing_req(struct l2cap_conn *conn, struct sk_buff *skb)
return SMP_AUTH_REQUIREMENTS;
}
- build_pairing_cmd(conn, req, &rsp, auth);
-
- if (rsp.auth_req & SMP_AUTH_SC)
- set_bit(SMP_FLAG_SC, &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;
@@ -1901,12 +1913,54 @@ static int smp_cmd_sign_info(struct l2cap_conn *conn, struct sk_buff *skb)
return 0;
}
+static u8 sc_select_method(struct smp_chan *smp)
+{
+ struct l2cap_conn *conn = smp->conn;
+ struct hci_conn *hcon = conn->hcon;
+ struct smp_cmd_pairing *local, *remote;
+ u8 local_mitm, remote_mitm, local_io, remote_io, method;
+
+ /* The preq/prsp contain the raw Pairing Request/Response PDUs
+ * which are needed as inputs to some crypto functions. To get
+ * the "struct smp_cmd_pairing" from them we need to skip the
+ * first byte which contains the opcode.
+ */
+ if (hcon->out) {
+ local = (void *) &smp->preq[1];
+ remote = (void *) &smp->prsp[1];
+ } else {
+ local = (void *) &smp->prsp[1];
+ remote = (void *) &smp->preq[1];
+ }
+
+ local_io = local->io_capability;
+ remote_io = remote->io_capability;
+
+ local_mitm = (local->auth_req & SMP_AUTH_MITM);
+ remote_mitm = (remote->auth_req & SMP_AUTH_MITM);
+
+ /* If either side wants MITM, look up the method from the table,
+ * otherwise use JUST WORKS.
+ */
+ if (local_mitm || remote_mitm)
+ method = get_auth_method(smp, local_io, remote_io);
+ else
+ method = JUST_WORKS;
+
+ /* Don't confirm locally initiated pairing attempts */
+ if (method == JUST_CFM && test_bit(SMP_FLAG_INITIATOR, &smp->flags))
+ method = JUST_WORKS;
+
+ return method;
+}
+
static int smp_cmd_public_key(struct l2cap_conn *conn, struct sk_buff *skb)
{
struct smp_cmd_public_key *key = (void *) skb->data;
struct hci_conn *hcon = conn->hcon;
struct l2cap_chan *chan = conn->smp;
struct smp_chan *smp = chan->data;
+ struct hci_dev *hdev = hcon->hdev;
struct smp_cmd_pairing_confirm cfm;
int err;
@@ -1936,6 +1990,16 @@ static int smp_cmd_public_key(struct l2cap_conn *conn, struct sk_buff *skb)
set_bit(SMP_FLAG_REMOTE_PK, &smp->flags);
+ smp->method = sc_select_method(smp);
+
+ BT_DBG("%s selected method 0x%02x", hdev->name, smp->method);
+
+ /* JUST_WORKS and JUST_CFM result in an unauthenticated key */
+ if (smp->method == JUST_WORKS || smp->method == JUST_CFM)
+ hcon->pending_sec_level = BT_SECURITY_MEDIUM;
+ else
+ hcon->pending_sec_level = BT_SECURITY_FIPS;
+
/* The Initiating device waits for the non-initiating device to
* send the confirm value.
*/
--
2.1.0
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