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 
11 static 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  */
41 int 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 	/* clear current_password here and use user input from wmi_priv.current_password */
99 	if (!ret)
100 		memset(current_password, 0, 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 
107 out:
108 	kfree(buffer);
109 	mutex_unlock(&wmi_priv.mutex);
110 
111 	return ret;
112 }
113 
114 static 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 
122 static 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 
129 static const struct wmi_device_id bios_attr_pass_interface_id_table[] = {
130 	{ .guid_string = DELL_WMI_BIOS_PASSWORD_INTERFACE_GUID },
131 	{ },
132 };
133 static 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 
142 int init_bios_attr_pass_interface(void)
143 {
144 	return wmi_driver_register(&bios_attr_pass_interface_driver);
145 }
146 
147 void exit_bios_attr_pass_interface(void)
148 {
149 	wmi_driver_unregister(&bios_attr_pass_interface_driver);
150 }
151 
152 MODULE_DEVICE_TABLE(wmi, bios_attr_pass_interface_id_table);
153