[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/ext2/ioctl.c b/fs/ext2/ioctl.c
index b8ea11f..de876fa 100644
--- a/fs/ext2/ioctl.c
+++ b/fs/ext2/ioctl.c
@@ -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>
@@ -23,6 +24,7 @@
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);
@@ -34,14 +36,19 @@
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;
@@ -50,7 +57,8 @@
/* 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;
@@ -63,7 +71,8 @@
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;
}
}
@@ -75,20 +84,26 @@
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)
@@ -102,15 +117,16 @@
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;
@@ -131,6 +147,7 @@
rsv->rsv_goal_size = rsv_window_size;
}
mutex_unlock(&ei->truncate_mutex);
+ mnt_drop_write(filp->f_path.mnt);
return 0;
}
default: