Bluetooth: Add function for generating LE SC out-of-band data

This patch adds a smp_generate_oob function that allows to create
local out-of-band data that can be used for pairing and also provides
the confirmation and random value.

Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>

2 files changed, 54 insertions, 0 deletions

diff --git a/net/bluetooth/smp.c b/net/bluetooth/smp.c
index 12e9c833885b..1669e7127e2e 100644
--- a/net/bluetooth/smp.c
+++ b/net/bluetooth/smp.c
@@ -74,6 +74,12 @@ enum {
 };
 
 struct smp_dev {
+        /* Secure Connections OOB data */
+        u8                      local_pk[64];
+        u8                      local_sk[32];
+        u8                      local_rr[16];
+        bool                    debug_key;
+
         struct crypto_blkcipher *tfm_aes;
         struct crypto_hash      *tfm_cmac;
 };
@@ -526,6 +532,53 @@ int smp_generate_rpa(struct hci_dev *hdev, const u8 irk[16], bdaddr_t *rpa)
         return 0;
 }
 
+int smp_generate_oob(struct hci_dev *hdev, u8 hash[16], u8 rand[16])
+{
+        struct l2cap_chan *chan = hdev->smp_data;
+        struct smp_dev *smp;
+        int err;
+
+        if (!chan || !chan->data)
+                return -EOPNOTSUPP;
+
+        smp = chan->data;
+
+        if (hci_dev_test_flag(hdev, HCI_USE_DEBUG_KEYS)) {
+                BT_DBG("Using debug keys");
+                memcpy(smp->local_pk, debug_pk, 64);
+                memcpy(smp->local_sk, debug_sk, 32);
+                smp->debug_key = true;
+        } else {
+                while (true) {
+                        /* Generate local key pair for Secure Connections */
+                        if (!ecc_make_key(smp->local_pk, smp->local_sk))
+                                return -EIO;
+
+                        /* This is unlikely, but we need to check that
+                         * we didn't accidentially generate a debug key.
+                         */
+                        if (memcmp(smp->local_sk, debug_sk, 32))
+                                break;
+                }
+                smp->debug_key = false;
+        }
+
+        SMP_DBG("OOB Public Key X: %32phN", smp->local_pk);
+        SMP_DBG("OOB Public Key Y: %32phN", smp->local_pk + 32);
+        SMP_DBG("OOB Private Key:  %32phN", smp->local_sk);
+
+        get_random_bytes(smp->local_rr, 16);
+
+        err = smp_f4(smp->tfm_cmac, smp->local_pk, smp->local_pk,
+                     smp->local_rr, 0, hash);
+        if (err < 0)
+                return err;
+
+        memcpy(rand, smp->local_rr, 16);
+
+        return 0;
+}
+
 static void smp_send_cmd(struct l2cap_conn *conn, u8 code, u16 len, void *data)
 {
         struct l2cap_chan *chan = conn->smp;
diff --git a/net/bluetooth/smp.h b/net/bluetooth/smp.h
index 60c5b73fcb4b..6cf872563ea7 100644
--- a/net/bluetooth/smp.h
+++ b/net/bluetooth/smp.h
@@ -188,6 +188,7 @@ int smp_user_confirm_reply(struct hci_conn *conn, u16 mgmt_op, __le32 passkey);
 bool smp_irk_matches(struct hci_dev *hdev, const u8 irk[16],
                      const bdaddr_t *bdaddr);
 int smp_generate_rpa(struct hci_dev *hdev, const u8 irk[16], bdaddr_t *rpa);
+int smp_generate_oob(struct hci_dev *hdev, u8 hash[16], u8 rand[16]);
 
 int smp_register(struct hci_dev *hdev);
 void smp_unregister(struct hci_dev *hdev);