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#include <linux/mount.h>
  14
  15#include "internal.h"
  16
  17static ssize_t efivarfs_file_write(struct file *file,
  18                const char __user *userbuf, size_t count, loff_t *ppos)
  19{
  20        struct efivar_entry *var = file->private_data;
  21        void *data;
  22        u32 attributes;
  23        struct inode *inode = file->f_mapping->host;
  24        unsigned long datasize = count - sizeof(attributes);
  25        ssize_t bytes;
  26        bool set = false;
  27
  28        if (count < sizeof(attributes))
  29                return -EINVAL;
  30
  31        if (copy_from_user(&attributes, userbuf, sizeof(attributes)))
  32                return -EFAULT;
  33
  34        if (attributes & ~(EFI_VARIABLE_MASK))
  35                return -EINVAL;
  36
  37        data = memdup_user(userbuf + sizeof(attributes), datasize);
  38        if (IS_ERR(data))
  39                return PTR_ERR(data);
  40
  41        bytes = efivar_entry_set_get_size(var, attributes, &datasize,
  42                                          data, &set);
  43        if (!set && bytes) {
  44                if (bytes == -ENOENT)
  45                        bytes = -EIO;
  46                goto out;
  47        }
  48
  49        if (bytes == -ENOENT) {
  50                drop_nlink(inode);
  51                d_delete(file->f_path.dentry);
  52                dput(file->f_path.dentry);
  53        } else {
  54                inode_lock(inode);
  55                i_size_write(inode, datasize + sizeof(attributes));
  56                inode_unlock(inode);
  57        }
  58
  59        bytes = count;
  60
  61out:
  62        kfree(data);
  63
  64        return bytes;
  65}
  66
  67static 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
  79        /*
  80         * efivarfs represents uncommitted variables with
  81         * zero-length files. Reading them should return EOF.
  82         */
  83        if (err == -ENOENT)
  84                return 0;
  85        else if (err)
  86                return err;
  87
  88        data = kmalloc(datasize + sizeof(attributes), GFP_KERNEL);
  89
  90        if (!data)
  91                return -ENOMEM;
  92
  93        size = efivar_entry_get(var, &attributes, &datasize,
  94                                data + sizeof(attributes));
  95        if (size)
  96                goto out_free;
  97
  98        memcpy(data, &attributes, sizeof(attributes));
  99        size = simple_read_from_buffer(userbuf, count, ppos,
 100                                       data, datasize + sizeof(attributes));
 101out_free:
 102        kfree(data);
 103
 104        return size;
 105}
 106
 107static int
 108efivarfs_ioc_getxflags(struct file *file, void __user *arg)
 109{
 110        struct inode *inode = file->f_mapping->host;
 111        unsigned int i_flags;
 112        unsigned int flags = 0;
 113
 114        i_flags = inode->i_flags;
 115        if (i_flags & S_IMMUTABLE)
 116                flags |= FS_IMMUTABLE_FL;
 117
 118        if (copy_to_user(arg, &flags, sizeof(flags)))
 119                return -EFAULT;
 120        return 0;
 121}
 122
 123static int
 124efivarfs_ioc_setxflags(struct file *file, void __user *arg)
 125{
 126        struct inode *inode = file->f_mapping->host;
 127        unsigned int flags;
 128        unsigned int i_flags = 0;
 129        int error;
 130
 131        if (!inode_owner_or_capable(inode))
 132                return -EACCES;
 133
 134        if (copy_from_user(&flags, arg, sizeof(flags)))
 135                return -EFAULT;
 136
 137        if (flags & ~FS_IMMUTABLE_FL)
 138                return -EOPNOTSUPP;
 139
 140        if (!capable(CAP_LINUX_IMMUTABLE))
 141                return -EPERM;
 142
 143        if (flags & FS_IMMUTABLE_FL)
 144                i_flags |= S_IMMUTABLE;
 145
 146
 147        error = mnt_want_write_file(file);
 148        if (error)
 149                return error;
 150
 151        inode_lock(inode);
 152        inode_set_flags(inode, i_flags, S_IMMUTABLE);
 153        inode_unlock(inode);
 154
 155        mnt_drop_write_file(file);
 156
 157        return 0;
 158}
 159
 160static long
 161efivarfs_file_ioctl(struct file *file, unsigned int cmd, unsigned long p)
 162{
 163        void __user *arg = (void __user *)p;
 164
 165        switch (cmd) {
 166        case FS_IOC_GETFLAGS:
 167                return efivarfs_ioc_getxflags(file, arg);
 168        case FS_IOC_SETFLAGS:
 169                return efivarfs_ioc_setxflags(file, arg);
 170        }
 171
 172        return -ENOTTY;
 173}
 174
 175const struct file_operations efivarfs_file_operations = {
 176        .open   = simple_open,
 177        .read   = efivarfs_file_read,
 178        .write  = efivarfs_file_write,
 179        .llseek = no_llseek,
 180        .unlocked_ioctl = efivarfs_file_ioctl,
 181};
 182