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Bluetooth: Add support for Pairing features exchange
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This patch implements a simple version of the SMP Pairing Features
exchange procedure (Vol. 3 Part H, Section 2.3.5.1).

For now, everything that would cause a Pairing Method different of
Just Works to be chosen is rejected.

Signed-off-by: Vinicius Costa Gomes <vinicius.gomes@openbossa.org>
Signed-off-by: Gustavo F. Padovan <padovan@profusion.mobi>
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Vinicius Costa Gomes authored and Gustavo F. Padovan committed Jun 13, 2011
1 parent b8e66ea commit da85e5e
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Showing 2 changed files with 54 additions and 53 deletions.
1 change: 1 addition & 0 deletions net/bluetooth/hci_event.c
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Original file line number Diff line number Diff line change
Expand Up @@ -1622,6 +1622,7 @@ static inline void hci_encrypt_change_evt(struct hci_dev *hdev, struct sk_buff *
/* Encryption implies authentication */
conn->link_mode |= HCI_LM_AUTH;
conn->link_mode |= HCI_LM_ENCRYPT;
conn->sec_level = conn->pending_sec_level;
} else
conn->link_mode &= ~HCI_LM_ENCRYPT;
}
Expand Down
106 changes: 53 additions & 53 deletions net/bluetooth/smp.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -181,6 +181,18 @@ static void smp_send_cmd(struct l2cap_conn *conn, u8 code, u16 len, void *data)
hci_send_acl(conn->hcon, skb, 0);
}

static __u8 seclevel_to_authreq(__u8 level)
{
switch (level) {
case BT_SECURITY_HIGH:
/* Right now we don't support bonding */
return SMP_AUTH_MITM;

default:
return SMP_AUTH_NONE;
}
}

static void build_pairing_cmd(struct l2cap_conn *conn,
struct smp_cmd_pairing *cmd, __u8 authreq)
{
Expand All @@ -192,7 +204,7 @@ static void build_pairing_cmd(struct l2cap_conn *conn,
cmd->auth_req = authreq;
}

static void smp_cmd_pairing_req(struct l2cap_conn *conn, struct sk_buff *skb)
static u8 smp_cmd_pairing_req(struct l2cap_conn *conn, struct sk_buff *skb)
{
struct smp_cmd_pairing *rp = (void *) skb->data;

Expand All @@ -202,12 +214,11 @@ static void smp_cmd_pairing_req(struct l2cap_conn *conn, struct sk_buff *skb)
memcpy(&conn->preq[1], rp, sizeof(*rp));
skb_pull(skb, sizeof(*rp));

rp->io_capability = 0x00;
rp->oob_flag = 0x00;
rp->max_key_size = 16;
rp->init_key_dist = 0x00;
rp->resp_key_dist = 0x00;
rp->auth_req &= (SMP_AUTH_BONDING | SMP_AUTH_MITM);
if (rp->oob_flag)
return SMP_OOB_NOT_AVAIL;

/* We didn't start the pairing, so no requirements */
build_pairing_cmd(conn, rp, SMP_AUTH_NONE);

/* Just works */
memset(conn->tk, 0, sizeof(conn->tk));
Expand All @@ -216,9 +227,11 @@ static void smp_cmd_pairing_req(struct l2cap_conn *conn, struct sk_buff *skb)
memcpy(&conn->prsp[1], rp, sizeof(*rp));

smp_send_cmd(conn, SMP_CMD_PAIRING_RSP, sizeof(*rp), rp);

return 0;
}

static void smp_cmd_pairing_rsp(struct l2cap_conn *conn, struct sk_buff *skb)
static u8 smp_cmd_pairing_rsp(struct l2cap_conn *conn, struct sk_buff *skb)
{
struct smp_cmd_pairing *rp = (void *) skb->data;
struct smp_cmd_pairing_confirm cp;
Expand All @@ -228,29 +241,34 @@ static void smp_cmd_pairing_rsp(struct l2cap_conn *conn, struct sk_buff *skb)

BT_DBG("conn %p", conn);

skb_pull(skb, sizeof(*rp));

if (rp->oob_flag)
return SMP_OOB_NOT_AVAIL;

/* Just works */
memset(conn->tk, 0, sizeof(conn->tk));

conn->prsp[0] = SMP_CMD_PAIRING_RSP;
memcpy(&conn->prsp[1], rp, sizeof(*rp));
skb_pull(skb, sizeof(*rp));

ret = smp_rand(conn->prnd);
if (ret)
return;
return SMP_UNSPECIFIED;

ret = smp_c1(tfm, conn->tk, conn->prnd, conn->preq, conn->prsp, 0,
conn->src, conn->hcon->dst_type, conn->dst, res);
if (ret)
return;
return SMP_UNSPECIFIED;

swap128(res, cp.confirm_val);

smp_send_cmd(conn, SMP_CMD_PAIRING_CONFIRM, sizeof(cp), &cp);

return 0;
}

static void smp_cmd_pairing_confirm(struct l2cap_conn *conn,
struct sk_buff *skb)
static u8 smp_cmd_pairing_confirm(struct l2cap_conn *conn, struct sk_buff *skb)
{
struct crypto_blkcipher *tfm = conn->hcon->hdev->tfm;

Expand All @@ -272,21 +290,23 @@ static void smp_cmd_pairing_confirm(struct l2cap_conn *conn,

ret = smp_rand(conn->prnd);
if (ret)
return;
return SMP_UNSPECIFIED;

ret = smp_c1(tfm, conn->tk, conn->prnd, conn->preq, conn->prsp,
conn->hcon->dst_type, conn->dst,
0, conn->src, res);
if (ret)
return;
return SMP_CONFIRM_FAILED;

swap128(res, cp.confirm_val);

smp_send_cmd(conn, SMP_CMD_PAIRING_CONFIRM, sizeof(cp), &cp);
}

return 0;
}

static void smp_cmd_pairing_random(struct l2cap_conn *conn, struct sk_buff *skb)
static u8 smp_cmd_pairing_random(struct l2cap_conn *conn, struct sk_buff *skb)
{
struct hci_conn *hcon = conn->hcon;
struct crypto_blkcipher *tfm = hcon->hdev->tfm;
Expand All @@ -307,19 +327,15 @@ static void smp_cmd_pairing_random(struct l2cap_conn *conn, struct sk_buff *skb)
conn->hcon->dst_type, conn->dst, 0, conn->src,
res);
if (ret)
return;
return SMP_UNSPECIFIED;

BT_DBG("conn %p %s", conn, conn->hcon->out ? "master" : "slave");

swap128(res, confirm);

if (memcmp(conn->pcnf, confirm, sizeof(conn->pcnf)) != 0) {
struct smp_cmd_pairing_fail cp;

BT_ERR("Pairing failed (confirmation values mismatch)");
cp.reason = SMP_CONFIRM_FAILED;
smp_send_cmd(conn, SMP_CMD_PAIRING_FAIL, sizeof(cp), &cp);
return;
return SMP_CONFIRM_FAILED;
}

if (conn->hcon->out) {
Expand All @@ -341,9 +357,11 @@ static void smp_cmd_pairing_random(struct l2cap_conn *conn, struct sk_buff *skb)
smp_s1(tfm, conn->tk, conn->prnd, random, key);
swap128(key, hcon->ltk);
}

return 0;
}

static void smp_cmd_security_req(struct l2cap_conn *conn, struct sk_buff *skb)
static u8 smp_cmd_security_req(struct l2cap_conn *conn, struct sk_buff *skb)
{
struct smp_cmd_security_req *rp = (void *) skb->data;
struct smp_cmd_pairing cp;
Expand All @@ -352,36 +370,21 @@ static void smp_cmd_security_req(struct l2cap_conn *conn, struct sk_buff *skb)
BT_DBG("conn %p", conn);

if (test_bit(HCI_CONN_ENCRYPT_PEND, &hcon->pend))
return;
return 0;

skb_pull(skb, sizeof(*rp));
memset(&cp, 0, sizeof(cp));

cp.io_capability = 0x00;
cp.oob_flag = 0x00;
cp.max_key_size = 16;
cp.init_key_dist = 0x00;
cp.resp_key_dist = 0x00;
cp.auth_req = rp->auth_req & (SMP_AUTH_BONDING | SMP_AUTH_MITM);
memset(&cp, 0, sizeof(cp));
build_pairing_cmd(conn, &cp, rp->auth_req);

conn->preq[0] = SMP_CMD_PAIRING_REQ;
memcpy(&conn->preq[1], &cp, sizeof(cp));

smp_send_cmd(conn, SMP_CMD_PAIRING_REQ, sizeof(cp), &cp);

set_bit(HCI_CONN_ENCRYPT_PEND, &hcon->pend);
}

static __u8 seclevel_to_authreq(__u8 level)
{
switch (level) {
case BT_SECURITY_HIGH:
/* For now we don't support bonding */
return SMP_AUTH_MITM;

default:
return SMP_AUTH_NONE;
}
return 0;
}

int smp_conn_security(struct l2cap_conn *conn, __u8 sec_level)
Expand All @@ -407,13 +410,8 @@ int smp_conn_security(struct l2cap_conn *conn, __u8 sec_level)

if (hcon->link_mode & HCI_LM_MASTER) {
struct smp_cmd_pairing cp;
cp.io_capability = 0x00;
cp.oob_flag = 0x00;
cp.max_key_size = 16;
cp.init_key_dist = 0x00;
cp.resp_key_dist = 0x00;
cp.auth_req = authreq;

build_pairing_cmd(conn, &cp, authreq);
conn->preq[0] = SMP_CMD_PAIRING_REQ;
memcpy(&conn->preq[1], &cp, sizeof(cp));

Expand Down Expand Up @@ -446,26 +444,28 @@ int smp_sig_channel(struct l2cap_conn *conn, struct sk_buff *skb)

switch (code) {
case SMP_CMD_PAIRING_REQ:
smp_cmd_pairing_req(conn, skb);
reason = smp_cmd_pairing_req(conn, skb);
break;

case SMP_CMD_PAIRING_FAIL:
reason = 0;
err = -EPERM;
break;

case SMP_CMD_PAIRING_RSP:
smp_cmd_pairing_rsp(conn, skb);
reason = smp_cmd_pairing_rsp(conn, skb);
break;

case SMP_CMD_SECURITY_REQ:
smp_cmd_security_req(conn, skb);
reason = smp_cmd_security_req(conn, skb);
break;

case SMP_CMD_PAIRING_CONFIRM:
smp_cmd_pairing_confirm(conn, skb);
reason = smp_cmd_pairing_confirm(conn, skb);
break;

case SMP_CMD_PAIRING_RANDOM:
smp_cmd_pairing_random(conn, skb);
reason = smp_cmd_pairing_random(conn, skb);
break;

case SMP_CMD_ENCRYPT_INFO:
Expand Down

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