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	print_hex_dump_bytes("set new password data: ", DUMP_PREFIX_NONE, buffer, buffer_size);
97	ret = call_password_interface(wmi_priv.password_attr_wdev, buffer, buffer_size);
98	/* on success copy the new password to current password */
99	if (!ret)
100		strscpy(current_password, new, MAX_BUFF);
101	/* explain to user the detailed failure reason */
102	else if (ret == -EOPNOTSUPP)
103		dev_err(&wmi_priv.password_attr_wdev->dev, "admin password must be configured\n");
104	else if (ret == -EACCES)
105		dev_err(&wmi_priv.password_attr_wdev->dev, "invalid password\n");
106
107out:
108	kfree(buffer);
109	mutex_unlock(&wmi_priv.mutex);
110
111	return ret;
112}
113
114static int bios_attr_pass_interface_probe(struct wmi_device *wdev, const void *context)
115{
116	mutex_lock(&wmi_priv.mutex);
117	wmi_priv.password_attr_wdev = wdev;
118	mutex_unlock(&wmi_priv.mutex);
119	return 0;
120}
121
122static void bios_attr_pass_interface_remove(struct wmi_device *wdev)
123{
124	mutex_lock(&wmi_priv.mutex);
125	wmi_priv.password_attr_wdev = NULL;
126	mutex_unlock(&wmi_priv.mutex);
127}
128
129static const struct wmi_device_id bios_attr_pass_interface_id_table[] = {
130	{ .guid_string = DELL_WMI_BIOS_PASSWORD_INTERFACE_GUID },
131	{ },
132};
133static struct wmi_driver bios_attr_pass_interface_driver = {
134	.driver = {
135		.name = DRIVER_NAME"-password"
136	},
137	.probe = bios_attr_pass_interface_probe,
138	.remove = bios_attr_pass_interface_remove,
139	.id_table = bios_attr_pass_interface_id_table,
140};
141
142int init_bios_attr_pass_interface(void)
143{
144	return wmi_driver_register(&bios_attr_pass_interface_driver);
145}
146
147void exit_bios_attr_pass_interface(void)
148{
149	wmi_driver_unregister(&bios_attr_pass_interface_driver);
150}
151
152MODULE_DEVICE_TABLE(wmi, bios_attr_pass_interface_id_table);
153