LXR linux/fs/efivarfs/file.c

   1/*
   2 * Copyright (C) 2012 Red Hat, Inc.
   3 * Copyright (C) 2012 Jeremy Kerr <jeremy.kerr@canonical.com>
   4 *
   5 * This program is free software; you can redistribute it and/or modify
   6 * it under the terms of the GNU General Public License version 2 as
   7 * published by the Free Software Foundation.
   8 */
   9
  10#include <linux/efi.h>
  11#include <linux/fs.h>
  12#include <linux/slab.h>
  13
  14#include "internal.h"
  15
  16static ssize_t efivarfs_file_write(struct file *file,
  17                const char __user *userbuf, size_t count, loff_t *ppos)
  18{
  19        struct efivar_entry *var = file->private_data;
  20        void *data;
  21        u32 attributes;
  22        struct inode *inode = file->f_mapping->host;
  23        unsigned long datasize = count - sizeof(attributes);
  24        ssize_t bytes;
  25        bool set = false;
  26
  27        if (count < sizeof(attributes))
  28                return -EINVAL;
  29
  30        if (copy_from_user(&attributes, userbuf, sizeof(attributes)))
  31                return -EFAULT;
  32
  33        if (attributes & ~(EFI_VARIABLE_MASK))
  34                return -EINVAL;
  35
  36        data = memdup_user(userbuf + sizeof(attributes), datasize);
  37        if (IS_ERR(data))
  38                return PTR_ERR(data);
  39
  40        bytes = efivar_entry_set_get_size(var, attributes, &datasize,
  41                                          data, &set);
  42        if (!set && bytes) {
  43                if (bytes == -ENOENT)
  44                        bytes = -EIO;
  45                goto out;
  46        }
  47
  48        if (bytes == -ENOENT) {
  49                drop_nlink(inode);
  50                d_delete(file->f_path.dentry);
  51                dput(file->f_path.dentry);
  52        } else {
  53                mutex_lock(&inode->i_mutex);
  54                i_size_write(inode, datasize + sizeof(attributes));
  55                mutex_unlock(&inode->i_mutex);
  56        }
  57
  58        bytes = count;
  59
  60out:
  61        kfree(data);
  62
  63        return bytes;
  64}
  65
  66static ssize_t efivarfs_file_read(struct file *file, char __user *userbuf,
  67                size_t count, loff_t *ppos)
  68{
  69        struct efivar_entry *var = file->private_data;
  70        unsigned long datasize = 0;
  71        u32 attributes;
  72        void *data;
  73        ssize_t size = 0;
  74        int err;
  75
  76        err = efivar_entry_size(var, &datasize);
  77
  78        /*
  79         * efivarfs represents uncommitted variables with
  80         * zero-length files. Reading them should return EOF.
  81         */
  82        if (err == -ENOENT)
  83                return 0;
  84        else if (err)
  85                return err;
  86
  87        data = kmalloc(datasize + sizeof(attributes), GFP_KERNEL);
  88
  89        if (!data)
  90                return -ENOMEM;
  91
  92        size = efivar_entry_get(var, &attributes, &datasize,
  93                                data + sizeof(attributes));
  94        if (size)
  95                goto out_free;
  96
  97        memcpy(data, &attributes, sizeof(attributes));
  98        size = simple_read_from_buffer(userbuf, count, ppos,
  99                                       data, datasize + sizeof(attributes));
 100out_free:
 101        kfree(data);
 102
 103        return size;
 104}
 105
 106const struct file_operations efivarfs_file_operations = {
 107        .open   = simple_open,
 108        .read   = efivarfs_file_read,
 109        .write  = efivarfs_file_write,
 110        .llseek = no_llseek,
 111};
 112