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aha/fs/ext4/ioctl.c
Akira Fujita 4a58579b9e ext4: Fix insufficient checks in EXT4_IOC_MOVE_EXT 
This patch fixes three problems in the handling of the
EXT4_IOC_MOVE_EXT ioctl:

1. In current EXT4_IOC_MOVE_EXT, there are read access mode checks for
original and donor files, but they allow the illegal write access to
donor file, since donor file is overwritten by original file data.  To
fix this problem, change access mode checks of original (r->r/w) and
donor (r->w) files.

2.  Disallow the use of donor files that have a setuid or setgid bits.

3.  Call mnt_want_write() and mnt_drop_write() before and after
ext4_move_extents() calling to get write access to a mount.

Signed-off-by: Akira Fujita <a-fujita@rs.jp.nec.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
2009-12-06 23:38:31 -05:00

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/*
* linux/fs/ext4/ioctl.c
*
* Copyright (C) 1993, 1994, 1995
* Remy Card (card@masi.ibp.fr)
* Laboratoire MASI - Institut Blaise Pascal
* Universite Pierre et Marie Curie (Paris VI)
*/
#include <linux/fs.h>
#include <linux/jbd2.h>
#include <linux/capability.h>
#include <linux/time.h>
#include <linux/compat.h>
#include <linux/mount.h>
#include <linux/file.h>
#include <asm/uaccess.h>
#include "ext4_jbd2.h"
#include "ext4.h"
long ext4_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
{
struct inode *inode = filp->f_dentry->d_inode;
struct ext4_inode_info *ei = EXT4_I(inode);
unsigned int flags;
ext4_debug("cmd = %u, arg = %lu\n", cmd, arg);
switch (cmd) {
case EXT4_IOC_GETFLAGS:
ext4_get_inode_flags(ei);
flags = ei->i_flags & EXT4_FL_USER_VISIBLE;
return put_user(flags, (int __user *) arg);
case EXT4_IOC_SETFLAGS: {
handle_t *handle = NULL;
int err, migrate = 0;
struct ext4_iloc iloc;
unsigned int oldflags;
unsigned int jflag;
if (!is_owner_or_cap(inode))
return -EACCES;
if (get_user(flags, (int __user *) arg))
return -EFAULT;
err = mnt_want_write(filp->f_path.mnt);
if (err)
return err;
flags = ext4_mask_flags(inode->i_mode, flags);
err = -EPERM;
mutex_lock(&inode->i_mutex);
/* Is it quota file? Do not allow user to mess with it */
if (IS_NOQUOTA(inode))
goto flags_out;
oldflags = ei->i_flags;
/* The JOURNAL_DATA flag is modifiable only by root */
jflag = flags & EXT4_JOURNAL_DATA_FL;
/*
* The IMMUTABLE and APPEND_ONLY flags can only be changed by
* the relevant capability.
*
* This test looks nicer. Thanks to Pauline Middelink
*/
if ((flags ^ oldflags) & (EXT4_APPEND_FL | EXT4_IMMUTABLE_FL)) {
if (!capable(CAP_LINUX_IMMUTABLE))
goto flags_out;
}
/*
* The JOURNAL_DATA flag can only be changed by
* the relevant capability.
*/
if ((jflag ^ oldflags) & (EXT4_JOURNAL_DATA_FL)) {
if (!capable(CAP_SYS_RESOURCE))
goto flags_out;
}
if (oldflags & EXT4_EXTENTS_FL) {
/* We don't support clearning extent flags */
if (!(flags & EXT4_EXTENTS_FL)) {
err = -EOPNOTSUPP;
goto flags_out;
}
} else if (flags & EXT4_EXTENTS_FL) {
/* migrate the file */
migrate = 1;
flags &= ~EXT4_EXTENTS_FL;
}
handle = ext4_journal_start(inode, 1);
if (IS_ERR(handle)) {
err = PTR_ERR(handle);
goto flags_out;
}
if (IS_SYNC(inode))
ext4_handle_sync(handle);
err = ext4_reserve_inode_write(handle, inode, &iloc);
if (err)
goto flags_err;
flags = flags & EXT4_FL_USER_MODIFIABLE;
flags |= oldflags & ~EXT4_FL_USER_MODIFIABLE;
ei->i_flags = flags;
ext4_set_inode_flags(inode);
inode->i_ctime = ext4_current_time(inode);
err = ext4_mark_iloc_dirty(handle, inode, &iloc);
flags_err:
ext4_journal_stop(handle);
if (err)
goto flags_out;
if ((jflag ^ oldflags) & (EXT4_JOURNAL_DATA_FL))
err = ext4_change_inode_journal_flag(inode, jflag);
if (err)
goto flags_out;
if (migrate)
err = ext4_ext_migrate(inode);
flags_out:
mutex_unlock(&inode->i_mutex);
mnt_drop_write(filp->f_path.mnt);
return err;
}
case EXT4_IOC_GETVERSION:
case EXT4_IOC_GETVERSION_OLD:
return put_user(inode->i_generation, (int __user *) arg);
case EXT4_IOC_SETVERSION:
case EXT4_IOC_SETVERSION_OLD: {
handle_t *handle;
struct ext4_iloc iloc;
__u32 generation;
int err;
if (!is_owner_or_cap(inode))
return -EPERM;
err = mnt_want_write(filp->f_path.mnt);
if (err)
return err;
if (get_user(generation, (int __user *) arg)) {
err = -EFAULT;
goto setversion_out;
}
handle = ext4_journal_start(inode, 1);
if (IS_ERR(handle)) {
err = PTR_ERR(handle);
goto setversion_out;
}
err = ext4_reserve_inode_write(handle, inode, &iloc);
if (err == 0) {
inode->i_ctime = ext4_current_time(inode);
inode->i_generation = generation;
err = ext4_mark_iloc_dirty(handle, inode, &iloc);
}
ext4_journal_stop(handle);
setversion_out:
mnt_drop_write(filp->f_path.mnt);
return err;
}
#ifdef CONFIG_JBD2_DEBUG
case EXT4_IOC_WAIT_FOR_READONLY:
/*
* This is racy - by the time we're woken up and running,
* the superblock could be released. And the module could
* have been unloaded. So sue me.
*
* Returns 1 if it slept, else zero.
*/
{
struct super_block *sb = inode->i_sb;
DECLARE_WAITQUEUE(wait, current);
int ret = 0;
set_current_state(TASK_INTERRUPTIBLE);
add_wait_queue(&EXT4_SB(sb)->ro_wait_queue, &wait);
if (timer_pending(&EXT4_SB(sb)->turn_ro_timer)) {
schedule();
ret = 1;
}
remove_wait_queue(&EXT4_SB(sb)->ro_wait_queue, &wait);
return ret;
}
#endif
case EXT4_IOC_GROUP_EXTEND: {
ext4_fsblk_t n_blocks_count;
struct super_block *sb = inode->i_sb;
int err, err2=0;
if (!capable(CAP_SYS_RESOURCE))
return -EPERM;
if (get_user(n_blocks_count, (__u32 __user *)arg))
return -EFAULT;
err = mnt_want_write(filp->f_path.mnt);
if (err)
return err;
err = ext4_group_extend(sb, EXT4_SB(sb)->s_es, n_blocks_count);
if (EXT4_SB(sb)->s_journal) {
jbd2_journal_lock_updates(EXT4_SB(sb)->s_journal);
err2 = jbd2_journal_flush(EXT4_SB(sb)->s_journal);
jbd2_journal_unlock_updates(EXT4_SB(sb)->s_journal);
}
if (err == 0)
err = err2;
mnt_drop_write(filp->f_path.mnt);
return err;
}
case EXT4_IOC_MOVE_EXT: {
struct move_extent me;
struct file *donor_filp;
int err;
if (!(filp->f_mode & FMODE_READ) ||
!(filp->f_mode & FMODE_WRITE))
return -EBADF;
if (copy_from_user(&me,
(struct move_extent __user *)arg, sizeof(me)))
return -EFAULT;
me.moved_len = 0;
donor_filp = fget(me.donor_fd);
if (!donor_filp)
return -EBADF;
if (!(donor_filp->f_mode & FMODE_WRITE)) {
err = -EBADF;
goto mext_out;
}
err = mnt_want_write(filp->f_path.mnt);
if (err)
goto mext_out;
err = ext4_move_extents(filp, donor_filp, me.orig_start,
me.donor_start, me.len, &me.moved_len);
mnt_drop_write(filp->f_path.mnt);
if (me.moved_len > 0)
file_remove_suid(donor_filp);
if (copy_to_user((struct move_extent *)arg, &me, sizeof(me)))
err = -EFAULT;
mext_out:
fput(donor_filp);
return err;
}
case EXT4_IOC_GROUP_ADD: {
struct ext4_new_group_data input;
struct super_block *sb = inode->i_sb;
int err, err2=0;
if (!capable(CAP_SYS_RESOURCE))
return -EPERM;
if (copy_from_user(&input, (struct ext4_new_group_input __user *)arg,
sizeof(input)))
return -EFAULT;
err = mnt_want_write(filp->f_path.mnt);
if (err)
return err;
err = ext4_group_add(sb, &input);
if (EXT4_SB(sb)->s_journal) {
jbd2_journal_lock_updates(EXT4_SB(sb)->s_journal);
err2 = jbd2_journal_flush(EXT4_SB(sb)->s_journal);
jbd2_journal_unlock_updates(EXT4_SB(sb)->s_journal);
}
if (err == 0)
err = err2;
mnt_drop_write(filp->f_path.mnt);
return err;
}
case EXT4_IOC_MIGRATE:
{
int err;
if (!is_owner_or_cap(inode))
return -EACCES;
err = mnt_want_write(filp->f_path.mnt);
if (err)
return err;
/*
* inode_mutex prevent write and truncate on the file.
* Read still goes through. We take i_data_sem in
* ext4_ext_swap_inode_data before we switch the
* inode format to prevent read.
*/
mutex_lock(&(inode->i_mutex));
err = ext4_ext_migrate(inode);
mutex_unlock(&(inode->i_mutex));
mnt_drop_write(filp->f_path.mnt);
return err;
}
case EXT4_IOC_ALLOC_DA_BLKS:
{
int err;
if (!is_owner_or_cap(inode))
return -EACCES;
err = mnt_want_write(filp->f_path.mnt);
if (err)
return err;
err = ext4_alloc_da_blocks(inode);
mnt_drop_write(filp->f_path.mnt);
return err;
}
default:
return -ENOTTY;
}
}
#ifdef CONFIG_COMPAT
long ext4_compat_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
{
/* These are just misnamed, they actually get/put from/to user an int */
switch (cmd) {
case EXT4_IOC32_GETFLAGS:
cmd = EXT4_IOC_GETFLAGS;
break;
case EXT4_IOC32_SETFLAGS:
cmd = EXT4_IOC_SETFLAGS;
break;
case EXT4_IOC32_GETVERSION:
cmd = EXT4_IOC_GETVERSION;
break;
case EXT4_IOC32_SETVERSION:
cmd = EXT4_IOC_SETVERSION;
break;
case EXT4_IOC32_GROUP_EXTEND:
cmd = EXT4_IOC_GROUP_EXTEND;
break;
case EXT4_IOC32_GETVERSION_OLD:
cmd = EXT4_IOC_GETVERSION_OLD;
break;
case EXT4_IOC32_SETVERSION_OLD:
cmd = EXT4_IOC_SETVERSION_OLD;
break;
#ifdef CONFIG_JBD2_DEBUG
case EXT4_IOC32_WAIT_FOR_READONLY:
cmd = EXT4_IOC_WAIT_FOR_READONLY;
break;
#endif
case EXT4_IOC32_GETRSVSZ:
cmd = EXT4_IOC_GETRSVSZ;
break;
case EXT4_IOC32_SETRSVSZ:
cmd = EXT4_IOC_SETRSVSZ;
break;
case EXT4_IOC_GROUP_ADD:
break;
default:
return -ENOIOCTLCMD;
}
return ext4_ioctl(file, cmd, (unsigned long) compat_ptr(arg));
}
#endif
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