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
  13 #include "internal.h"
  14
  15 static ssize_t efivarfs_file_write(struct file *file,
  16                 const char __user *userbuf, size_t count, loff_t *ppos)
  17 {
  18         struct efivar_entry *var = file->private_data;
  19         void *data;
  20         u32 attributes;
  21         struct inode *inode = file->f_mapping->host;
  22         unsigned long datasize = count - sizeof(attributes);
  23         ssize_t bytes = 0;
  24         bool set = false;
  25
  26         if (count < sizeof(attributes))
  27                 return -EINVAL;
  28
  29         if (copy_from_user(&attributes, userbuf, sizeof(attributes)))
  30                 return -EFAULT;
  31
  32         if (attributes & ~(EFI_VARIABLE_MASK))
  33                 return -EINVAL;
  34
  35         data = kmalloc(datasize, GFP_KERNEL);
  36         if (!data)
  37                 return -ENOMEM;
  38
  39         if (copy_from_user(data, userbuf + sizeof(attributes), datasize)) {
  40                 bytes = -EFAULT;
  41                 goto out;
  42         }
  43
  44         bytes = efivar_entry_set_get_size(var, attributes, &datasize,
  45                                           data, &set);
  46         if (!set && bytes)
  47                 goto out;
  48
  49         if (bytes == -ENOENT) {
  50                 drop_nlink(inode);
  51                 d_delete(file->f_dentry);
  52                 dput(file->f_dentry);
  53         } else {
  54                 mutex_lock(&inode->i_mutex);
  55                 i_size_write(inode, datasize + sizeof(attributes));
  56                 mutex_unlock(&inode->i_mutex);
  57         }
  58
  59         bytes = count;
  60
  61 out:
  62         kfree(data);
  63
  64         return bytes;
  65 }
  66
  67 static ssize_t efivarfs_file_read(struct file *file, char __user *userbuf,
  68                 size_t count, loff_t *ppos)
  69 {
  70         struct efivar_entry *var = file->private_data;
  71         unsigned long datasize = 0;
  72         u32 attributes;
  73         void *data;
  74         ssize_t size = 0;
  75         int err;
  76
  77         err = efivar_entry_size(var, &datasize);
  78         if (err)
  79                 return err;
  80
  81         data = kmalloc(datasize + sizeof(attributes), GFP_KERNEL);
  82
  83         if (!data)
  84                 return -ENOMEM;
  85
  86         size = efivar_entry_get(var, &attributes, &datasize,
  87                                 data + sizeof(attributes));
  88         if (size)
  89                 goto out_free;
  90
  91         memcpy(data, &attributes, sizeof(attributes));
  92         size = simple_read_from_buffer(userbuf, count, ppos,
  93                                        data, datasize + sizeof(attributes));
  94 out_free:
  95         kfree(data);
  96
  97         return size;
  98 }
  99
 100 const struct file_operations efivarfs_file_operations = {
 101         .open   = simple_open,
 102         .read   = efivarfs_file_read,
 103         .write  = efivarfs_file_write,
 104         .llseek = no_llseek,
 105 };