[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/ext3/ioctl.c b/fs/ext3/ioctl.c
index 023a070..0d0c701 100644
--- a/fs/ext3/ioctl.c
+++ b/fs/ext3/ioctl.c
@@ -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>
@@ -38,14 +39,19 @@
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;
@@ -54,7 +60,8 @@
/* 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;
@@ -70,7 +77,8 @@
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;
}
}
@@ -81,7 +89,8 @@
if ((jflag ^ oldflags) & (EXT3_JOURNAL_DATA_FL)) {
if (!capable(CAP_SYS_RESOURCE)) {
mutex_unlock(&inode->i_mutex);
- return -EPERM;
+ err = -EPERM;
+ goto flags_out;
}
}
@@ -89,7 +98,8 @@
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;
@@ -115,6 +125,8 @@
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:
@@ -129,14 +141,18 @@
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;
@@ -144,6 +160,8 @@
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
@@ -179,18 +197,24 @@
}
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;
@@ -208,7 +232,9 @@
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;
@@ -218,17 +244,20 @@
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 (get_user(n_blocks_count, (__u32 __user *)arg))
- return -EFAULT;
-
+ 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: {
@@ -239,18 +268,22 @@
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;
}