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Bluetooth: Add selection of the SC authentication method

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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@intel.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
This commit is contained in:
Johan Hedberg 2014-05-31 18:51:02 +03:00 committed by Marcel Holtmann
parent 783e057462
commit 5e3d3d9b3c
1 changed files with 69 additions and 5 deletions
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74
net/bluetooth/smp.c
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@ -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.
*/