Bluetooth: Add smp_irk_matches helper function

This patch adds a helper function to check whether a given IRK matches a
given Resolvable Private Address (RPA). The function will be needed for
implementing the rest of address resolving support.

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 ae487e17380ef5bbbb2195cadc4e1daa2f28ee19..5f500b479f45ead68a28cc1853923b83997d77e0 100644 (file)
--- a/net/bluetooth/smp.c
+++ b/net/bluetooth/smp.c
@@ -78,6 +78,52 @@ static int smp_e(struct crypto_blkcipher *tfm, const u8 *k, u8 *r)
        return err;
 }
 
+static int smp_ah(struct crypto_blkcipher *tfm, u8 irk[16], u8 r[3], u8 res[3])
+{
+       u8 _res[16], k[16];
+       int err;
+
+       /* r' = padding || r */
+       memset(_res, 0, 13);
+       _res[13] = r[2];
+       _res[14] = r[1];
+       _res[15] = r[0];
+
+       swap128(irk, k);
+       err = smp_e(tfm, k, _res);
+       if (err) {
+               BT_ERR("Encrypt error");
+               return err;
+       }
+
+       /* The output of the random address function ah is:
+        *      ah(h, r) = e(k, r') mod 2^24
+        * The output of the security function e is then truncated to 24 bits
+        * by taking the least significant 24 bits of the output of e as the
+        * result of ah.
+        */
+       res[0] = _res[15];
+       res[1] = _res[14];
+       res[2] = _res[13];
+
+       return 0;
+}
+
+bool smp_irk_matches(struct crypto_blkcipher *tfm, u8 irk[16],
+                    bdaddr_t *bdaddr)
+{
+       u8 hash[3];
+       int err;
+
+       BT_DBG("RPA %pMR IRK %*phN", bdaddr, 16, irk);
+
+       err = smp_ah(tfm, irk, &bdaddr->b[3], hash);
+       if (err)
+               return false;
+
+       return !memcmp(bdaddr->b, hash, 3);
+}
+
 static int smp_c1(struct crypto_blkcipher *tfm, u8 k[16], u8 r[16],
                  u8 preq[7], u8 pres[7], u8 _iat, bdaddr_t *ia,
                  u8 _rat, bdaddr_t *ra, u8 res[16])

diff --git a/net/bluetooth/smp.h b/net/bluetooth/smp.h
index 777ee93a6c9bffe46215f8d23cd1634e0fb48682..950d039c2ea28338b4c889a5d6fa9bc7607350bb 100644 (file)
--- a/net/bluetooth/smp.h
+++ b/net/bluetooth/smp.h
@@ -143,4 +143,7 @@ int smp_user_confirm_reply(struct hci_conn *conn, u16 mgmt_op, __le32 passkey);
 
 void smp_chan_destroy(struct l2cap_conn *conn);
 
+bool smp_irk_matches(struct crypto_blkcipher *tfm, u8 irk[16],
+                    bdaddr_t *bdaddr);
+
 #endif /* __SMP_H */