Bluetooth: Add support for LE SC numeric comparison
After the Pairing Confirm and Random PDUs have been exchanged in LE SC
it's time to generate a numeric comparison value using a new smp_g2
cryptographic function (which also builds on AES-CMAC). This patch adds
the smp_g2 implementation and updates the Pairing Random PDU handler to
proceed with the value genration and user confirmation.
Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
diff --git a/net/bluetooth/smp.c b/net/bluetooth/smp.c
index 6207f32..103f05a 100644
--- a/net/bluetooth/smp.c
+++ b/net/bluetooth/smp.c
@@ -175,6 +175,32 @@
return err;
}
+static int smp_g2(struct crypto_hash *tfm_cmac, const u8 u[32], const u8 v[32],
+ const u8 x[16], const u8 y[16], u32 *val)
+{
+ u8 m[80], tmp[16];
+ int err;
+
+ BT_DBG("u %32phN", u);
+ BT_DBG("v %32phN", v);
+ BT_DBG("x %16phN y %16phN", x, y);
+
+ memcpy(m, y, 16);
+ memcpy(m + 16, v, 32);
+ memcpy(m + 48, u, 32);
+
+ err = aes_cmac(tfm_cmac, x, m, sizeof(m), tmp);
+ if (err)
+ return err;
+
+ *val = get_unaligned_le32(tmp);
+ *val %= 1000000;
+
+ BT_DBG("val %06u", *val);
+
+ return 0;
+}
+
static int smp_e(struct crypto_blkcipher *tfm, const u8 *k, u8 *r)
{
struct blkcipher_desc desc;
@@ -1270,6 +1296,10 @@
{
struct l2cap_chan *chan = conn->smp;
struct smp_chan *smp = chan->data;
+ struct hci_conn *hcon = conn->hcon;
+ u8 *pkax, *pkbx, *na, *nb;
+ u32 passkey;
+ int err;
BT_DBG("conn %p", conn);
@@ -1279,7 +1309,46 @@
memcpy(smp->rrnd, skb->data, sizeof(smp->rrnd));
skb_pull(skb, sizeof(smp->rrnd));
- return smp_random(smp);
+ if (!test_bit(SMP_FLAG_SC, &smp->flags))
+ return smp_random(smp);
+
+ if (hcon->out) {
+ u8 cfm[16];
+
+ err = smp_f4(smp->tfm_cmac, smp->remote_pk, smp->local_pk,
+ smp->rrnd, 0, cfm);
+ if (err)
+ return SMP_UNSPECIFIED;
+
+ if (memcmp(smp->pcnf, cfm, 16))
+ return SMP_CONFIRM_FAILED;
+
+ pkax = smp->local_pk;
+ pkbx = smp->remote_pk;
+ na = smp->prnd;
+ nb = smp->rrnd;
+ } else {
+ smp_send_cmd(conn, SMP_CMD_PAIRING_RANDOM, sizeof(smp->prnd),
+ smp->prnd);
+ SMP_ALLOW_CMD(smp, SMP_CMD_DHKEY_CHECK);
+
+ pkax = smp->remote_pk;
+ pkbx = smp->local_pk;
+ na = smp->rrnd;
+ nb = smp->prnd;
+ }
+
+ err = smp_g2(smp->tfm_cmac, pkax, pkbx, na, nb, &passkey);
+ if (err)
+ return SMP_UNSPECIFIED;
+
+ err = mgmt_user_confirm_request(hcon->hdev, &hcon->dst,
+ hcon->type, hcon->dst_type,
+ passkey, 0);
+ if (err)
+ return SMP_UNSPECIFIED;
+
+ return 0;
}
static bool smp_ltk_encrypt(struct l2cap_conn *conn, u8 sec_level)