Bluetooth: Add MITM mechanism to LE-SMP

To achive Man-In-The-Middle (MITM) level security with Low Energy,
we have to enable User Passkey Comparison.  This commit modifies the
hard-coded JUST-WORKS pairing mechanism to support query via the MGMT
interface of Passkey comparison and User Confirmation.

Signed-off-by: Brian Gix <bgix@codeaurora.org>
Acked-by: Marcel Holtmann<marcel@holtmann.org>
Signed-off-by: Gustavo F. Padovan <padovan@profusion.mobi>

include/net/bluetooth/hci_core.h

@@ -310,6 +310,7 @@ struct hci_conn {
 	struct hci_dev	*hdev;
 	void		*l2cap_data;
 	void		*sco_data;
+	void		*smp_conn;
 
 	struct hci_conn	*link;
 

include/net/bluetooth/smp.h

@@ -115,6 +115,10 @@ struct smp_cmd_security_req {
 #define SMP_MIN_ENC_KEY_SIZE		7
 #define SMP_MAX_ENC_KEY_SIZE		16
 
+#define SMP_FLAG_TK_VALID	1
+#define SMP_FLAG_CFM_PENDING	2
+#define SMP_FLAG_MITM_AUTH	3
+
 struct smp_chan {
 	struct l2cap_conn *conn;
 	u8		preq[7]; /* SMP Pairing Request */
@@ -124,6 +128,7 @@ struct smp_chan {
 	u8		pcnf[16]; /* SMP Pairing Confirm */
 	u8		tk[16]; /* SMP Temporary Key */
 	u8		smp_key_size;
+	unsigned long	smp_flags;
 	struct crypto_blkcipher	*tfm;
 	struct work_struct confirm;
 	struct work_struct random;
@@ -134,6 +139,7 @@ struct smp_chan {
 int smp_conn_security(struct l2cap_conn *conn, __u8 sec_level);
 int smp_sig_channel(struct l2cap_conn *conn, struct sk_buff *skb);
 int smp_distribute_keys(struct l2cap_conn *conn, __u8 force);
+int smp_user_confirm_reply(struct hci_conn *conn, u16 mgmt_op, __le32 passkey);
 
 void smp_chan_destroy(struct l2cap_conn *conn);