passwordattr-interface.c

  1// SPDX-License-Identifier: GPL-2.0
  2/*
  3 * Functions corresponding to SET password methods under BIOS attributes interface GUID
  4 *
  5 *  Copyright (c) 2020 Dell Inc.
  6 */
  7
  8#include <linux/wmi.h>
  9#include "dell-wmi-sysman.h"
 10
 11static int call_password_interface(struct wmi_device *wdev, char *in_args, size_t size)
 12{
 13	struct acpi_buffer output = {ACPI_ALLOCATE_BUFFER, NULL};
 14	struct acpi_buffer input;
 15	union acpi_object *obj;
 16	acpi_status status;
 17	int ret = -EIO;
 18
 19	input.length =  (acpi_size) size;
 20	input.pointer = in_args;
 21	status = wmidev_evaluate_method(wdev, 0, 1, &input, &output);
 22	if (ACPI_FAILURE(status))
 23		return -EIO;
 24	obj = (union acpi_object *)output.pointer;
 25	if (obj->type == ACPI_TYPE_INTEGER)
 26		ret = obj->integer.value;
 27
 28	kfree(output.pointer);
 29	/* let userland know it may need to check is_password_set again */
 30	kobject_uevent(&wmi_priv.class_dev->kobj, KOBJ_CHANGE);
 31	return map_wmi_error(ret);
 32}
 33
 34/**
 35 * set_new_password() - Sets a system admin password
 36 * @password_type: The type of password to set
 37 * @new: The new password
 38 *
 39 * Sets the password using plaintext interface
 40 */
 41int set_new_password(const char *password_type, const char *new)
 42{
 43	size_t password_type_size, current_password_size, new_size;
 44	size_t security_area_size, buffer_size;
 45	char *buffer = NULL, *start;
 46	char *current_password;
 47	int ret;
 48
 49	mutex_lock(&wmi_priv.mutex);
 50	if (!wmi_priv.password_attr_wdev) {
 51		ret = -ENODEV;
 52		goto out;
 53	}
 54	if (strcmp(password_type, "Admin") == 0) {
 55		current_password = wmi_priv.current_admin_password;
 56	} else if (strcmp(password_type, "System") == 0) {
 57		current_password = wmi_priv.current_system_password;
 58	} else {
 59		ret = -EINVAL;
 60		dev_err(&wmi_priv.password_attr_wdev->dev, "unknown password type %s\n",
 61			password_type);
 62		goto out;
 63	}
 64
 65	/* build/calculate buffer */
 66	security_area_size = calculate_security_buffer(wmi_priv.current_admin_password);
 67	password_type_size = calculate_string_buffer(password_type);
 68	current_password_size = calculate_string_buffer(current_password);
 69	new_size = calculate_string_buffer(new);
 70	buffer_size = security_area_size + password_type_size + current_password_size + new_size;
 71	buffer = kzalloc(buffer_size, GFP_KERNEL);
 72	if (!buffer) {
 73		ret = -ENOMEM;
 74		goto out;
 75	}
 76
 77	/* build security area */
 78	populate_security_buffer(buffer, wmi_priv.current_admin_password);
 79
 80	/* build variables to set */
 81	start = buffer + security_area_size;
 82	ret = populate_string_buffer(start, password_type_size, password_type);
 83	if (ret < 0)
 84		goto out;
 85
 86	start += ret;
 87	ret = populate_string_buffer(start, current_password_size, current_password);
 88	if (ret < 0)
 89		goto out;
 90
 91	start += ret;
 92	ret = populate_string_buffer(start, new_size, new);
 93	if (ret < 0)
 94		goto out;
 95
 96	ret = call_password_interface(wmi_priv.password_attr_wdev, buffer, buffer_size);
 97	/* on success copy the new password to current password */
 98	if (!ret)
 99		strscpy(current_password, new, MAX_BUFF);
100	/* explain to user the detailed failure reason */
101	else if (ret == -EOPNOTSUPP)
102		dev_err(&wmi_priv.password_attr_wdev->dev, "admin password must be configured\n");
103	else if (ret == -EACCES)
104		dev_err(&wmi_priv.password_attr_wdev->dev, "invalid password\n");
105
106out:
107	kfree(buffer);
108	mutex_unlock(&wmi_priv.mutex);
109
110	return ret;
111}
112
113static int bios_attr_pass_interface_probe(struct wmi_device *wdev, const void *context)
114{
115	mutex_lock(&wmi_priv.mutex);
116	wmi_priv.password_attr_wdev = wdev;
117	mutex_unlock(&wmi_priv.mutex);
118	return 0;
119}
120
121static void bios_attr_pass_interface_remove(struct wmi_device *wdev)
122{
123	mutex_lock(&wmi_priv.mutex);
124	wmi_priv.password_attr_wdev = NULL;
125	mutex_unlock(&wmi_priv.mutex);
126}
127
128static const struct wmi_device_id bios_attr_pass_interface_id_table[] = {
129	{ .guid_string = DELL_WMI_BIOS_PASSWORD_INTERFACE_GUID },
130	{ },
131};
132static struct wmi_driver bios_attr_pass_interface_driver = {
133	.driver = {
134		.name = DRIVER_NAME"-password"
135	},
136	.probe = bios_attr_pass_interface_probe,
137	.remove = bios_attr_pass_interface_remove,
138	.id_table = bios_attr_pass_interface_id_table,
139};
140
141int init_bios_attr_pass_interface(void)
142{
143	return wmi_driver_register(&bios_attr_pass_interface_driver);
144}
145
146void exit_bios_attr_pass_interface(void)
147{
148	wmi_driver_unregister(&bios_attr_pass_interface_driver);
149}
150
151MODULE_DEVICE_TABLE(wmi, bios_attr_pass_interface_id_table);