Bluetooth: Add AES crypto context for each HCI device

Previously the crypto context has only been available for LE SMP
sessions, but now that we'll need to perform operations also during
discovery it makes sense to have this context part of the hci_dev
struct. Later, the context can be removed from the SMP context.
Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>

include/net/bluetooth/hci_core.h

@@ -259,6 +259,7 @@ struct hci_dev {
 	__u32			req_status;
 	__u32			req_result;
 
+	struct crypto_blkcipher	*tfm_aes;
 
 	struct discovery_state	discovery;
 	struct hci_conn_hash	conn_hash;

net/bluetooth/hci_core.c

@@ -29,6 +29,7 @@
 #include <linux/idr.h>
 #include <linux/rfkill.h>
 #include <linux/debugfs.h>
+#include <linux/crypto.h>
 #include <asm/unaligned.h>
 
 #include <net/bluetooth/bluetooth.h>
@@ -3205,9 +3206,18 @@ int hci_register_dev(struct hci_dev *hdev)
 
 	dev_set_name(&hdev->dev, "%s", hdev->name);
 
+	hdev->tfm_aes = crypto_alloc_blkcipher("ecb(aes)", 0,
+					       CRYPTO_ALG_ASYNC);
+	if (IS_ERR(hdev->tfm_aes)) {
+		BT_ERR("Unable to create crypto context");
+		error = PTR_ERR(hdev->tfm_aes);
+		hdev->tfm_aes = NULL;
+		goto err_wqueue;
+	}
+
 	error = device_add(&hdev->dev);
 	if (error < 0)
-		goto err_wqueue;
+		goto err_tfm;
 
 	hdev->rfkill = rfkill_alloc(hdev->name, &hdev->dev,
 				    RFKILL_TYPE_BLUETOOTH, &hci_rfkill_ops,
@@ -3243,6 +3253,8 @@ int hci_register_dev(struct hci_dev *hdev)
 
 	return id;
 
+err_tfm:
+	crypto_free_blkcipher(hdev->tfm_aes);
 err_wqueue:
 	destroy_workqueue(hdev->workqueue);
 	destroy_workqueue(hdev->req_workqueue);
@@ -3293,6 +3305,9 @@ void hci_unregister_dev(struct hci_dev *hdev)
 		rfkill_destroy(hdev->rfkill);
 	}
 
+	if (hdev->tfm_aes)
+		crypto_free_blkcipher(hdev->tfm_aes);
+
 	device_del(&hdev->dev);
 
 	debugfs_remove_recursive(hdev->debugfs);