projects / linux-block.git / blame
| Commit | Line | Data |
|---|---|---|
| 09c434b8 | 1 | // SPDX-License-Identifier: GPL-2.0-only |
| 526b4af4 | 2 | /* |
| 5baa1be1 | 3 | * custom_method.c - debugfs interface for customizing ACPI control method |
| 526b4af4 TR |
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> | |
| 8b48463f | 11 | #include <linux/acpi.h> |
| f474e148 | 12 | #include <linux/security.h> |
| 526b4af4 TR |
13 | |
| 14 | #include "internal.h" | |
| 15 | ||
| 526b4af4 TR |
16 | MODULE_LICENSE("GPL"); |
| 17 | ||
| 18 | static struct dentry *cm_dentry; | |
| 19 | ||
| 20 | /* /sys/kernel/debug/acpi/custom_method */ | |
| 21 | ||
| 4dea6e89 | 22 | static ssize_t cm_write(struct file *file, const char __user *user_buf, |
| 526b4af4 TR |
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; | |
| f474e148 MG |
31 | int ret; |
| 32 | ||
| 33 | ret = security_locked_down(LOCKDOWN_ACPI_TABLES); | |
| 34 | if (ret) | |
| 35 | return ret; | |
| 526b4af4 TR |
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; | |
| 1cfd8956 ML |
45 | /* make sure the buf is not allocated */ |
| 46 | kfree(buf); | |
| 526b4af4 TR |
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) || | |
| 03d1571d WW |
58 | (count > uncopied_bytes)) { |
| 59 | kfree(buf); | |
| e483bb9a | 60 | buf = NULL; |
| 526b4af4 | 61 | return -EINVAL; |
| 03d1571d | 62 | } |
| 526b4af4 TR |
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; | |
| 373d4d09 | 79 | add_taint(TAINT_OVERRIDDEN_ACPI_TABLE, LOCKDEP_NOW_UNRELIABLE); |
| 526b4af4 TR |
80 | } |
| 81 | ||
| 82 | return count; | |
| 83 | } | |
| 84 | ||
| 85 | static const struct file_operations cm_fops = { | |
| 86 | .write = cm_write, | |
| 87 | .llseek = default_llseek, | |
| 88 | }; | |
| 89 | ||
| 90 | static int __init acpi_custom_method_init(void) | |
| 91 | { | |
| 526b4af4 TR |
92 | cm_dentry = debugfs_create_file("custom_method", S_IWUSR, |
| 93 | acpi_debugfs_dir, NULL, &cm_fops); | |
| 526b4af4 TR |
94 | return 0; |
| 95 | } | |
| 96 | ||
| 97 | static void __exit acpi_custom_method_exit(void) | |
| 98 | { | |
| 7e79a692 | 99 | debugfs_remove(cm_dentry); |
| 447a5647 | 100 | } |
| 526b4af4 TR |
101 | |
| 102 | module_init(acpi_custom_method_init); | |
| 103 | module_exit(acpi_custom_method_exit); |