Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
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kernel
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linux
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 buf = kzalloc(max_size, GFP_KERNEL);
46 if (!buf)
47 return -ENOMEM;
48 }
49
50 if (buf == NULL)
51 return -EINVAL;
52
53 if ((*ppos > max_size) ||
54 (*ppos + count > max_size) ||
55 (*ppos + count < count) ||
56 (count > uncopied_bytes)) {
57 kfree(buf);
58 return -EINVAL;
59 }
60
61 if (copy_from_user(buf + (*ppos), user_buf, count)) {
62 kfree(buf);
63 buf = NULL;
64 return -EFAULT;
65 }
66
67 uncopied_bytes -= count;
68 *ppos += count;
69
70 if (!uncopied_bytes) {
71 status = acpi_install_method(buf);
72 kfree(buf);
73 buf = NULL;
74 if (ACPI_FAILURE(status))
75 return -EINVAL;
76 add_taint(TAINT_OVERRIDDEN_ACPI_TABLE, LOCKDEP_NOW_UNRELIABLE);
77 }
78
79 kfree(buf);
80 return count;
81}
82
83static const struct file_operations cm_fops = {
84 .write = cm_write,
85 .llseek = default_llseek,
86};
87
88static int __init acpi_custom_method_init(void)
89{
90 cm_dentry = debugfs_create_file("custom_method", S_IWUSR,
91 acpi_debugfs_dir, NULL, &cm_fops);
92 return 0;
93}
94
95static void __exit acpi_custom_method_exit(void)
96{
97 debugfs_remove(cm_dentry);
98}
99
100module_init(acpi_custom_method_init);
101module_exit(acpi_custom_method_exit);