[PATCH] r/o bind mounts: elevate write count for ioctls()
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>
diff --git a/fs/ext4/ioctl.c b/fs/ext4/ioctl.c
index 2ed7c37..25b13ed 100644
--- a/fs/ext4/ioctl.c
+++ b/fs/ext4/ioctl.c
@@ -15,6 +15,7 @@
#include <linux/time.h>
#include <linux/compat.h>
#include <linux/smp_lock.h>
+#include <linux/mount.h>
#include <asm/uaccess.h>
int ext4_ioctl (struct inode * inode, struct file * filp, unsigned int cmd,
@@ -38,24 +39,25 @@
unsigned int oldflags;
unsigned int jflag;
- if (IS_RDONLY(inode))
- return -EROFS;
-
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;
+
if (!S_ISDIR(inode->i_mode))
flags &= ~EXT4_DIRSYNC_FL;
+ err = -EPERM;
mutex_lock(&inode->i_mutex);
/* Is it quota file? Do not allow user to mess with it */
- if (IS_NOQUOTA(inode)) {
- mutex_unlock(&inode->i_mutex);
- return -EPERM;
- }
+ if (IS_NOQUOTA(inode))
+ goto flags_out;
+
oldflags = ei->i_flags;
/* The JOURNAL_DATA flag is modifiable only by root */
@@ -68,10 +70,8 @@
* This test looks nicer. Thanks to Pauline Middelink
*/
if ((flags ^ oldflags) & (EXT4_APPEND_FL | EXT4_IMMUTABLE_FL)) {
- if (!capable(CAP_LINUX_IMMUTABLE)) {
- mutex_unlock(&inode->i_mutex);
- return -EPERM;
- }
+ if (!capable(CAP_LINUX_IMMUTABLE))
+ goto flags_out;
}
/*
@@ -79,17 +79,14 @@
* the relevant capability.
*/
if ((jflag ^ oldflags) & (EXT4_JOURNAL_DATA_FL)) {
- if (!capable(CAP_SYS_RESOURCE)) {
- mutex_unlock(&inode->i_mutex);
- return -EPERM;
- }
+ if (!capable(CAP_SYS_RESOURCE))
+ goto flags_out;
}
-
handle = ext4_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;
@@ -107,14 +104,14 @@
err = ext4_mark_iloc_dirty(handle, inode, &iloc);
flags_err:
ext4_journal_stop(handle);
- if (err) {
- mutex_unlock(&inode->i_mutex);
- return err;
- }
+ if (err)
+ goto flags_out;
if ((jflag ^ oldflags) & (EXT4_JOURNAL_DATA_FL))
err = ext4_change_inode_journal_flag(inode, jflag);
+flags_out:
mutex_unlock(&inode->i_mutex);
+ mnt_drop_write(filp->f_path.mnt);
return err;
}
case EXT4_IOC_GETVERSION:
@@ -129,14 +126,20 @@
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 = ext4_journal_start(inode, 1);
- if (IS_ERR(handle))
- return PTR_ERR(handle);
+ 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);
@@ -144,6 +147,8 @@
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
@@ -179,19 +184,21 @@
}
return -ENOTTY;
case EXT4_IOC_SETRSVSZ: {
+ int err;
if (!test_opt(inode->i_sb, RESERVATION) ||!S_ISREG(inode->i_mode))
return -ENOTTY;
- if (IS_RDONLY(inode))
- return -EROFS;
-
if (!is_owner_or_cap(inode))
return -EACCES;
if (get_user(rsv_window_size, (int __user *)arg))
return -EFAULT;
+ err = mnt_want_write(filp->f_path.mnt);
+ if (err)
+ return err;
+
if (rsv_window_size > EXT4_MAX_RESERVE_BLOCKS)
rsv_window_size = EXT4_MAX_RESERVE_BLOCKS;
@@ -208,6 +215,7 @@
rsv->rsv_goal_size = rsv_window_size;
}
up_write(&ei->i_data_sem);
+ mnt_drop_write(filp->f_path.mnt);
return 0;
}
case EXT4_IOC_GROUP_EXTEND: {
@@ -218,16 +226,18 @@
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;
+
err = ext4_group_extend(sb, EXT4_SB(sb)->s_es, n_blocks_count);
jbd2_journal_lock_updates(EXT4_SB(sb)->s_journal);
jbd2_journal_flush(EXT4_SB(sb)->s_journal);
jbd2_journal_unlock_updates(EXT4_SB(sb)->s_journal);
+ mnt_drop_write(filp->f_path.mnt);
return err;
}
@@ -239,17 +249,19 @@
if (!capable(CAP_SYS_RESOURCE))
return -EPERM;
- if (IS_RDONLY(inode))
- return -EROFS;
-
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);
jbd2_journal_lock_updates(EXT4_SB(sb)->s_journal);
jbd2_journal_flush(EXT4_SB(sb)->s_journal);
jbd2_journal_unlock_updates(EXT4_SB(sb)->s_journal);
+ mnt_drop_write(filp->f_path.mnt);
return err;
}