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Bluetooth: Add support for sending LE SC Confirm value 

Once the public key exchange is complete the next step is for the
non-initiating device to send a SMP Pairing Confirm PDU to the
initiating device. This requires the use of a new smp_f4 confirm value
generation function which in turn builds on the AES-CMAC cryptographic
function.

Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
This commit is contained in:
Johan Hedberg 2014-06-06 11:30:08 +03:00 committed by Marcel Holtmann
parent d8f8edbe93
commit cbbbe3e242
1 changed files with 96 additions and 0 deletions
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96
net/bluetooth/smp.c
View File

@ -43,6 +43,9 @@
0x1f : 0x07)
#define KEY_DIST_MASK 0x07
/* Maximum message length that can be passed to aes_cmac */
#define CMAC_MSG_MAX 80
enum {
SMP_FLAG_TK_VALID,
SMP_FLAG_CFM_PENDING,
@ -94,6 +97,84 @@ static inline void swap_buf(const u8 *src, u8 *dst, size_t len)
dst[len - 1 - i] = src[i];
}
static int aes_cmac(struct crypto_hash *tfm, const u8 k[16], const u8 *m,
size_t len, u8 mac[16])
{
uint8_t tmp[16], mac_msb[16], msg_msb[CMAC_MSG_MAX];
struct hash_desc desc;
struct scatterlist sg;
int err;
if (len > CMAC_MSG_MAX)
return -EFBIG;
if (!tfm) {
BT_ERR("tfm %p", tfm);
return -EINVAL;
}
desc.tfm = tfm;
desc.flags = 0;
crypto_hash_init(&desc);
/* Swap key and message from LSB to MSB */
swap_buf(k, tmp, 16);
swap_buf(m, msg_msb, len);
BT_DBG("msg (len %zu) %*phN", len, (int) len, m);
BT_DBG("key %16phN", k);
err = crypto_hash_setkey(tfm, tmp, 16);
if (err) {
BT_ERR("cipher setkey failed: %d", err);
return err;
}
sg_init_one(&sg, msg_msb, len);
err = crypto_hash_update(&desc, &sg, len);
if (err) {
BT_ERR("Hash update error %d", err);
return err;
}
err = crypto_hash_final(&desc, mac_msb);
if (err) {
BT_ERR("Hash final error %d", err);
return err;
}
swap_buf(mac_msb, mac, 16);
BT_DBG("mac %16phN", mac);
return 0;
}
static int smp_f4(struct crypto_hash *tfm_cmac, const u8 u[32], const u8 v[32],
const u8 x[16], u8 z, u8 res[16])
{
u8 m[65];
int err;
BT_DBG("u %32phN", u);
BT_DBG("v %32phN", v);
BT_DBG("x %16phN z %02x", x, z);
m[0] = z;
memcpy(m + 1, v, 32);
memcpy(m + 33, u, 32);
err = aes_cmac(tfm_cmac, x, m, sizeof(m), res);
if (err)
return err;
BT_DBG("res %16phN", res);
return err;
}
static int smp_e(struct crypto_blkcipher *tfm, const u8 *k, u8 *r)
{
struct blkcipher_desc desc;
@ -1522,6 +1603,7 @@ static int smp_cmd_public_key(struct l2cap_conn *conn, struct sk_buff *skb)
struct hci_conn *hcon = conn->hcon;
struct l2cap_chan *chan = conn->smp;
struct smp_chan *smp = chan->data;
struct smp_cmd_pairing_confirm cfm;
int err;
BT_DBG("conn %p", conn);
@ -1550,6 +1632,20 @@ static int smp_cmd_public_key(struct l2cap_conn *conn, struct sk_buff *skb)
set_bit(SMP_FLAG_REMOTE_PK, &smp->flags);
/* The Initiating device waits for the non-initiating device to
* send the confirm value.
*/
if (conn->hcon->out)
return 0;
err = smp_f4(smp->tfm_cmac, smp->local_pk, smp->remote_pk, smp->prnd,
0, cfm.confirm_val);
if (err)
return SMP_UNSPECIFIED;
smp_send_cmd(conn, SMP_CMD_PAIRING_CONFIRM, sizeof(cfm), &cfm);
SMP_ALLOW_CMD(smp, SMP_CMD_PAIRING_RANDOM);
return 0;
}