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[PATCH] r/o bind mounts: elevate write count for ioctls()
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Some ioctl()s can cause writes to the filesystem.  Take these, and make them
use mnt_want/drop_write() instead.

[AV: updated]

Acked-by: Al Viro <viro@ZenIV.linux.org.uk>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Dave Hansen <haveblue@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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@hansendc
hansendc authored and Al Viro committed Apr 19, 2008
1 parent 20ddee2 commit 42a74f2
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Showing 9 changed files with 265 additions and 155 deletions.
57 changes: 37 additions & 20 deletions fs/ext2/ioctl.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -12,6 +12,7 @@
#include <linux/time.h>
#include <linux/sched.h>
#include <linux/compat.h>
#include <linux/mount.h>
#include <linux/smp_lock.h>
#include <asm/current.h>
#include <asm/uaccess.h>
Expand All @@ -23,6 +24,7 @@ long ext2_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
struct ext2_inode_info *ei = EXT2_I(inode);
unsigned int flags;
unsigned short rsv_window_size;
int ret;

ext2_debug ("cmd = %u, arg = %lu\n", cmd, arg);

Expand All @@ -34,14 +36,19 @@ long ext2_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
case EXT2_IOC_SETFLAGS: {
unsigned int oldflags;

if (IS_RDONLY(inode))
return -EROFS;
ret = mnt_want_write(filp->f_path.mnt);
if (ret)
return ret;

if (!is_owner_or_cap(inode))
return -EACCES;
if (!is_owner_or_cap(inode)) {
ret = -EACCES;
goto setflags_out;
}

if (get_user(flags, (int __user *) arg))
return -EFAULT;
if (get_user(flags, (int __user *) arg)) {
ret = -EFAULT;
goto setflags_out;
}

if (!S_ISDIR(inode->i_mode))
flags &= ~EXT2_DIRSYNC_FL;
Expand All @@ -50,7 +57,8 @@ long ext2_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
/* Is it quota file? Do not allow user to mess with it */
if (IS_NOQUOTA(inode)) {
mutex_unlock(&inode->i_mutex);
return -EPERM;
ret = -EPERM;
goto setflags_out;
}
oldflags = ei->i_flags;

Expand All @@ -63,7 +71,8 @@ long ext2_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
if ((flags ^ oldflags) & (EXT2_APPEND_FL | EXT2_IMMUTABLE_FL)) {
if (!capable(CAP_LINUX_IMMUTABLE)) {
mutex_unlock(&inode->i_mutex);
return -EPERM;
ret = -EPERM;
goto setflags_out;
}
}

Expand All @@ -75,20 +84,26 @@ long ext2_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
ext2_set_inode_flags(inode);
inode->i_ctime = CURRENT_TIME_SEC;
mark_inode_dirty(inode);
return 0;
setflags_out:
mnt_drop_write(filp->f_path.mnt);
return ret;
}
case EXT2_IOC_GETVERSION:
return put_user(inode->i_generation, (int __user *) arg);
case EXT2_IOC_SETVERSION:
if (!is_owner_or_cap(inode))
return -EPERM;
if (IS_RDONLY(inode))
return -EROFS;
if (get_user(inode->i_generation, (int __user *) arg))
return -EFAULT;
inode->i_ctime = CURRENT_TIME_SEC;
mark_inode_dirty(inode);
return 0;
ret = mnt_want_write(filp->f_path.mnt);
if (ret)
return ret;
if (get_user(inode->i_generation, (int __user *) arg)) {
ret = -EFAULT;
} else {
inode->i_ctime = CURRENT_TIME_SEC;
mark_inode_dirty(inode);
}
mnt_drop_write(filp->f_path.mnt);
return ret;
case EXT2_IOC_GETRSVSZ:
if (test_opt(inode->i_sb, RESERVATION)
&& S_ISREG(inode->i_mode)
Expand All @@ -102,15 +117,16 @@ long ext2_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
if (!test_opt(inode->i_sb, RESERVATION) ||!S_ISREG(inode->i_mode))
return -ENOTTY;

if (IS_RDONLY(inode))
return -EROFS;

if ((current->fsuid != inode->i_uid) && !capable(CAP_FOWNER))
if (!is_owner_or_cap(inode))
return -EACCES;

if (get_user(rsv_window_size, (int __user *)arg))
return -EFAULT;

ret = mnt_want_write(filp->f_path.mnt);
if (ret)
return ret;

if (rsv_window_size > EXT2_MAX_RESERVE_BLOCKS)
rsv_window_size = EXT2_MAX_RESERVE_BLOCKS;

Expand All @@ -131,6 +147,7 @@ long ext2_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
rsv->rsv_goal_size = rsv_window_size;
}
mutex_unlock(&ei->truncate_mutex);
mnt_drop_write(filp->f_path.mnt);
return 0;
}
default:
Expand Down
103 changes: 68 additions & 35 deletions fs/ext3/ioctl.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -12,6 +12,7 @@
#include <linux/capability.h>
#include <linux/ext3_fs.h>
#include <linux/ext3_jbd.h>
#include <linux/mount.h>
#include <linux/time.h>
#include <linux/compat.h>
#include <linux/smp_lock.h>
Expand All @@ -38,14 +39,19 @@ int ext3_ioctl (struct inode * inode, struct file * filp, unsigned int cmd,
unsigned int oldflags;
unsigned int jflag;

if (IS_RDONLY(inode))
return -EROFS;
err = mnt_want_write(filp->f_path.mnt);
if (err)
return err;

if (!is_owner_or_cap(inode))
return -EACCES;
if (!is_owner_or_cap(inode)) {
err = -EACCES;
goto flags_out;
}

if (get_user(flags, (int __user *) arg))
return -EFAULT;
if (get_user(flags, (int __user *) arg)) {
err = -EFAULT;
goto flags_out;
}

if (!S_ISDIR(inode->i_mode))
flags &= ~EXT3_DIRSYNC_FL;
Expand All @@ -54,7 +60,8 @@ int ext3_ioctl (struct inode * inode, struct file * filp, unsigned int cmd,
/* Is it quota file? Do not allow user to mess with it */
if (IS_NOQUOTA(inode)) {
mutex_unlock(&inode->i_mutex);
return -EPERM;
err = -EPERM;
goto flags_out;
}
oldflags = ei->i_flags;

Expand All @@ -70,7 +77,8 @@ int ext3_ioctl (struct inode * inode, struct file * filp, unsigned int cmd,
if ((flags ^ oldflags) & (EXT3_APPEND_FL | EXT3_IMMUTABLE_FL)) {
if (!capable(CAP_LINUX_IMMUTABLE)) {
mutex_unlock(&inode->i_mutex);
return -EPERM;
err = -EPERM;
goto flags_out;
}
}

Expand All @@ -81,15 +89,17 @@ int ext3_ioctl (struct inode * inode, struct file * filp, unsigned int cmd,
if ((jflag ^ oldflags) & (EXT3_JOURNAL_DATA_FL)) {
if (!capable(CAP_SYS_RESOURCE)) {
mutex_unlock(&inode->i_mutex);
return -EPERM;
err = -EPERM;
goto flags_out;
}
}


handle = ext3_journal_start(inode, 1);
if (IS_ERR(handle)) {
mutex_unlock(&inode->i_mutex);
return PTR_ERR(handle);
err = PTR_ERR(handle);
goto flags_out;
}
if (IS_SYNC(inode))
handle->h_sync = 1;
Expand All @@ -115,6 +125,8 @@ int ext3_ioctl (struct inode * inode, struct file * filp, unsigned int cmd,
if ((jflag ^ oldflags) & (EXT3_JOURNAL_DATA_FL))
err = ext3_change_inode_journal_flag(inode, jflag);
mutex_unlock(&inode->i_mutex);
flags_out:
mnt_drop_write(filp->f_path.mnt);
return err;
}
case EXT3_IOC_GETVERSION:
Expand All @@ -129,21 +141,27 @@ int ext3_ioctl (struct inode * inode, struct file * filp, unsigned int cmd,

if (!is_owner_or_cap(inode))
return -EPERM;
if (IS_RDONLY(inode))
return -EROFS;
if (get_user(generation, (int __user *) arg))
return -EFAULT;

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 = ext3_journal_start(inode, 1);
if (IS_ERR(handle))
return PTR_ERR(handle);
if (IS_ERR(handle)) {
err = PTR_ERR(handle);
goto setversion_out;
}
err = ext3_reserve_inode_write(handle, inode, &iloc);
if (err == 0) {
inode->i_ctime = CURRENT_TIME_SEC;
inode->i_generation = generation;
err = ext3_mark_iloc_dirty(handle, inode, &iloc);
}
ext3_journal_stop(handle);
setversion_out:
mnt_drop_write(filp->f_path.mnt);
return err;
}
#ifdef CONFIG_JBD_DEBUG
Expand Down Expand Up @@ -179,18 +197,24 @@ int ext3_ioctl (struct inode * inode, struct file * filp, unsigned int cmd,
}
return -ENOTTY;
case EXT3_IOC_SETRSVSZ: {
int err;

if (!test_opt(inode->i_sb, RESERVATION) ||!S_ISREG(inode->i_mode))
return -ENOTTY;

if (IS_RDONLY(inode))
return -EROFS;
err = mnt_want_write(filp->f_path.mnt);
if (err)
return err;

if (!is_owner_or_cap(inode))
return -EACCES;
if (!is_owner_or_cap(inode)) {
err = -EACCES;
goto setrsvsz_out;
}

if (get_user(rsv_window_size, (int __user *)arg))
return -EFAULT;
if (get_user(rsv_window_size, (int __user *)arg)) {
err = -EFAULT;
goto setrsvsz_out;
}

if (rsv_window_size > EXT3_MAX_RESERVE_BLOCKS)
rsv_window_size = EXT3_MAX_RESERVE_BLOCKS;
Expand All @@ -208,7 +232,9 @@ int ext3_ioctl (struct inode * inode, struct file * filp, unsigned int cmd,
rsv->rsv_goal_size = rsv_window_size;
}
mutex_unlock(&ei->truncate_mutex);
return 0;
setrsvsz_out:
mnt_drop_write(filp->f_path.mnt);
return err;
}
case EXT3_IOC_GROUP_EXTEND: {
ext3_fsblk_t n_blocks_count;
Expand All @@ -218,17 +244,20 @@ int ext3_ioctl (struct inode * inode, struct file * filp, unsigned int cmd,
if (!capable(CAP_SYS_RESOURCE))
return -EPERM;

if (IS_RDONLY(inode))
return -EROFS;

if (get_user(n_blocks_count, (__u32 __user *)arg))
return -EFAULT;
err = mnt_want_write(filp->f_path.mnt);
if (err)
return err;

if (get_user(n_blocks_count, (__u32 __user *)arg)) {
err = -EFAULT;
goto group_extend_out;
}
err = ext3_group_extend(sb, EXT3_SB(sb)->s_es, n_blocks_count);
journal_lock_updates(EXT3_SB(sb)->s_journal);
journal_flush(EXT3_SB(sb)->s_journal);
journal_unlock_updates(EXT3_SB(sb)->s_journal);

group_extend_out:
mnt_drop_write(filp->f_path.mnt);
return err;
}
case EXT3_IOC_GROUP_ADD: {
Expand All @@ -239,18 +268,22 @@ int ext3_ioctl (struct inode * inode, struct file * filp, unsigned int cmd,
if (!capable(CAP_SYS_RESOURCE))
return -EPERM;

if (IS_RDONLY(inode))
return -EROFS;
err = mnt_want_write(filp->f_path.mnt);
if (err)
return err;

if (copy_from_user(&input, (struct ext3_new_group_input __user *)arg,
sizeof(input)))
return -EFAULT;
sizeof(input))) {
err = -EFAULT;
goto group_add_out;
}

err = ext3_group_add(sb, &input);
journal_lock_updates(EXT3_SB(sb)->s_journal);
journal_flush(EXT3_SB(sb)->s_journal);
journal_unlock_updates(EXT3_SB(sb)->s_journal);

group_add_out:
mnt_drop_write(filp->f_path.mnt);
return err;
}

Expand Down
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