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1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * custom_method.c - debugfs interface for customizing ACPI control method
4 */
5
6#include <linux/init.h>
7#include <linux/module.h>
8#include <linux/kernel.h>
9#include <linux/uaccess.h>
10#include <linux/debugfs.h>
11#include <linux/acpi.h>
12#include <linux/security.h>
13
14#include "internal.h"
15
16#define _COMPONENT ACPI_SYSTEM_COMPONENT
17ACPI_MODULE_NAME("custom_method");
18MODULE_LICENSE("GPL");
19
20static struct dentry *cm_dentry;
21
22/* /sys/kernel/debug/acpi/custom_method */
23
24static ssize_t cm_write(struct file *file, const char __user * user_buf,
25 size_t count, loff_t *ppos)
26{
27 static char *buf;
28 static u32 max_size;
29 static u32 uncopied_bytes;
30
31 struct acpi_table_header table;
32 acpi_status status;
33 int ret;
34
35 ret = security_locked_down(LOCKDOWN_ACPI_TABLES);
36 if (ret)
37 return ret;
38
39 if (!(*ppos)) {
40 /* parse the table header to get the table length */
41 if (count <= sizeof(struct acpi_table_header))
42 return -EINVAL;
43 if (copy_from_user(&table, user_buf,
44 sizeof(struct acpi_table_header)))
45 return -EFAULT;
46 uncopied_bytes = max_size = table.length;
47 buf = kzalloc(max_size, GFP_KERNEL);
48 if (!buf)
49 return -ENOMEM;
50 }
51
52 if (buf == NULL)
53 return -EINVAL;
54
55 if ((*ppos > max_size) ||
56 (*ppos + count > max_size) ||
57 (*ppos + count < count) ||
58 (count > uncopied_bytes)) {
59 kfree(buf);
60 return -EINVAL;
61 }
62
63 if (copy_from_user(buf + (*ppos), user_buf, count)) {
64 kfree(buf);
65 buf = NULL;
66 return -EFAULT;
67 }
68
69 uncopied_bytes -= count;
70 *ppos += count;
71
72 if (!uncopied_bytes) {
73 status = acpi_install_method(buf);
74 kfree(buf);
75 buf = NULL;
76 if (ACPI_FAILURE(status))
77 return -EINVAL;
78 add_taint(TAINT_OVERRIDDEN_ACPI_TABLE, LOCKDEP_NOW_UNRELIABLE);
79 }
80
81 kfree(buf);
82 return count;
83}
84
85static const struct file_operations cm_fops = {
86 .write = cm_write,
87 .llseek = default_llseek,
88};
89
90static int __init acpi_custom_method_init(void)
91{
92 cm_dentry = debugfs_create_file("custom_method", S_IWUSR,
93 acpi_debugfs_dir, NULL, &cm_fops);
94 return 0;
95}
96
97static void __exit acpi_custom_method_exit(void)
98{
99 debugfs_remove(cm_dentry);
100}
101
102module_init(acpi_custom_method_init);
103module_exit(acpi_custom_method_exit);
1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * custom_method.c - debugfs interface for customizing ACPI control method
4 */
5
6#include <linux/init.h>
7#include <linux/module.h>
8#include <linux/kernel.h>
9#include <linux/uaccess.h>
10#include <linux/debugfs.h>
11#include <linux/acpi.h>
12#include <linux/security.h>
13
14#include "internal.h"
15
16MODULE_LICENSE("GPL");
17
18static struct dentry *cm_dentry;
19
20/* /sys/kernel/debug/acpi/custom_method */
21
22static ssize_t cm_write(struct file *file, const char __user *user_buf,
23 size_t count, loff_t *ppos)
24{
25 static char *buf;
26 static u32 max_size;
27 static u32 uncopied_bytes;
28
29 struct acpi_table_header table;
30 acpi_status status;
31 int ret;
32
33 ret = security_locked_down(LOCKDOWN_ACPI_TABLES);
34 if (ret)
35 return ret;
36
37 if (!(*ppos)) {
38 /* parse the table header to get the table length */
39 if (count <= sizeof(struct acpi_table_header))
40 return -EINVAL;
41 if (copy_from_user(&table, user_buf,
42 sizeof(struct acpi_table_header)))
43 return -EFAULT;
44 uncopied_bytes = max_size = table.length;
45 /* make sure the buf is not allocated */
46 kfree(buf);
47 buf = kzalloc(max_size, GFP_KERNEL);
48 if (!buf)
49 return -ENOMEM;
50 }
51
52 if (buf == NULL)
53 return -EINVAL;
54
55 if ((*ppos > max_size) ||
56 (*ppos + count > max_size) ||
57 (*ppos + count < count) ||
58 (count > uncopied_bytes)) {
59 kfree(buf);
60 buf = NULL;
61 return -EINVAL;
62 }
63
64 if (copy_from_user(buf + (*ppos), user_buf, count)) {
65 kfree(buf);
66 buf = NULL;
67 return -EFAULT;
68 }
69
70 uncopied_bytes -= count;
71 *ppos += count;
72
73 if (!uncopied_bytes) {
74 status = acpi_install_method(buf);
75 kfree(buf);
76 buf = NULL;
77 if (ACPI_FAILURE(status))
78 return -EINVAL;
79 add_taint(TAINT_OVERRIDDEN_ACPI_TABLE, LOCKDEP_NOW_UNRELIABLE);
80 }
81
82 return count;
83}
84
85static const struct file_operations cm_fops = {
86 .write = cm_write,
87 .llseek = default_llseek,
88};
89
90static int __init acpi_custom_method_init(void)
91{
92 cm_dentry = debugfs_create_file("custom_method", S_IWUSR,
93 acpi_debugfs_dir, NULL, &cm_fops);
94 return 0;
95}
96
97static void __exit acpi_custom_method_exit(void)
98{
99 debugfs_remove(cm_dentry);
100}
101
102module_init(acpi_custom_method_init);
103module_exit(acpi_custom_method_exit);