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