commit 335d3fc57941e5c6164c69d439aec1cb7a800876 upstream.
Overlayfs's volatile option allows the user to bypass all forced sync calls
to the upperdir filesystem. This comes at the cost of safety. We can never
ensure that the user's data is intact, but we can make a best effort to
expose whether or not the data is likely to be in a bad state.
The best way to handle this in the time being is that if an overlayfs's
upperdir experiences an error after a volatile mount occurs, that error
will be returned on fsync, fdatasync, sync, and syncfs. This is
contradictory to the traditional behaviour of VFS which fails the call
once, and only raises an error if a subsequent fsync error has occurred,
and been raised by the filesystem.
One awkward aspect of the patch is that we have to manually set the
superblock's errseq_t after the sync_fs callback as opposed to just
returning an error from syncfs. This is because the call chain looks
something like this:
sys_syncfs ->
sync_filesystem ->
__sync_filesystem ->
/* The return value is ignored here
sb->s_op->sync_fs(sb)
_sync_blockdev
/* Where the VFS fetches the error to raise to userspace */
errseq_check_and_advance
Because of this we call errseq_set every time the sync_fs callback occurs.
Due to the nature of this seen / unseen dichotomy, if the upperdir is an
inconsistent state at the initial mount time, overlayfs will refuse to
mount, as overlayfs cannot get a snapshot of the upperdir's errseq that
will increment on error until the user calls syncfs.
Signed-off-by: Sargun Dhillon <sargun@sargun.me>
Suggested-by: Amir Goldstein <amir73il@gmail.com>
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Fixes: c86243b090 ("ovl: provide a mount option "volatile"")
Cc: stable@vger.kernel.org
Reviewed-by: Vivek Goyal <vgoyal@redhat.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit b854cc659dcb80f172cb35dbedc15d39d49c383f upstream.
The function ovl_dir_real_file() currently uses the inode lock to serialize
writes to the od->upperfile field.
However, this function will get called by ovl_ioctl_set_flags(), which
utilizes the inode lock too. In this case ovl_dir_real_file() will try to
claim a lock that is owned by a function in its call stack, which won't get
released before ovl_dir_real_file() returns.
Fix by replacing the open coded compare and exchange by an explicit atomic
op.
Fixes: 61536bed21 ("ovl: support [S|G]ETFLAGS and FS[S|G]ETXATTR ioctls for directories")
Cc: stable@vger.kernel.org # v5.10
Reported-by: Icenowy Zheng <icenowy@aosc.io>
Tested-by: Icenowy Zheng <icenowy@aosc.io>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit 89bdfaf93d9157499c3a0d61f489df66f2dead7f upstream.
ovl_ioctl_set_flags() does a capability check using flags, but then the
real ioctl double-fetches flags and uses potentially different value.
The "Check the capability before cred override" comment misleading: user
can skip this check by presenting benign flags first and then overwriting
them to non-benign flags.
Just remove the cred override for now, hoping this doesn't cause a
regression.
The proper solution is to create a new setxflags i_op (patches are in the
works).
Xfstests don't show a regression.
Reported-by: Dmitry Vyukov <dvyukov@google.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Fixes: dab5ca8fd9 ("ovl: add lsattr/chattr support")
Cc: <stable@vger.kernel.org> # v4.19
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Canonalize to ioctl FS_* flags instead of inode S_* flags.
Note that we do not call the helper vfs_ioc_fssetxattr_check()
for FS_IOC_FSSETXATTR ioctl. The reason is that underlying filesystem
will perform all the checks. We only need to perform the capability
check before overriding credentials.
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Xiao Yang <yangx.jy@cn.fujitsu.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
[S|G]ETFLAGS and FS[S|G]ETXATTR ioctls are applicable to both files and
directories, so add ioctl operations to dir as well.
We teach ovl_real_fdget() to get the realfile of directories which use
a different type of file->private_data.
Ifdef away compat ioctl implementation to conform to standard practice.
With this change, xfstest generic/079 which tests these ioctls on files
and directories passes.
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Xiao Yang <yangx.jy@cn.fujitsu.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
ovl_can_list() should return false for overlay private xattrs. Since
currently these use the "trusted.overlay." prefix, they will always match
the "trusted." prefix as well, hence the test for being non-trusted will
not trigger.
Prepare for using the "user.overlay." namespace by moving the test for
private xattr before the test for non-trusted.
This patch doesn't change behavior.
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Instead of passing the xattr name down to the ovl_do_*xattr() accessor
functions, pass an enumerated value. The enum can use the same names as
the the previous #define for each xattr name.
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Call ovl_do_*xattr() when accessing an overlay private xattr, vfs_*xattr()
otherwise.
This has an effect on debug output, which is made more consistent by this
patch.
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Use the convention of calling ovl_do_foo() for operations which are overlay
specific.
This patch is a no-op, and will have significance for supporting
"user.overlay." xattr namespace.
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
This is a partial revert (with some cleanups) of commit 993a0b2aec ("ovl:
Do not lose security.capability xattr over metadata file copy-up"), which
introduced ovl_getxattr() in the first place.
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Lose the padding and the failure message (in line with other parts of the
copy up process). Return zero for both nonexistent or empty xattr.
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
ovl_getattr() returns the value of an xattr in a kmalloced buffer. There
are two callers:
ovl_copy_up_meta_inode_data() (copy_up.c)
ovl_get_redirect_xattr() (util.c)
This patch just copies ovl_getxattr() to copy_up.c, the following patches
will deal with the differences in idividual callers.
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Container folks are complaining that dnf/yum issues too many sync while
installing packages and this slows down the image build. Build requirement
is such that they don't care if a node goes down while build was still
going on. In that case, they will simply throw away unfinished layer and
start new build. So they don't care about syncing intermediate state to the
disk and hence don't want to pay the price associated with sync.
So they are asking for mount options where they can disable sync on overlay
mount point.
They primarily seem to have two use cases.
- For building images, they will mount overlay with nosync and then sync
upper layer after unmounting overlay and reuse upper as lower for next
layer.
- For running containers, they don't seem to care about syncing upper layer
because if node goes down, they will simply throw away upper layer and
create a fresh one.
So this patch provides a mount option "volatile" which disables all forms
of sync. Now it is caller's responsibility to throw away upper if system
crashes or shuts down and start fresh.
With "volatile", I am seeing roughly 20% speed up in my VM where I am just
installing emacs in an image. Installation time drops from 31 seconds to 25
seconds when nosync option is used. This is for the case of building on top
of an image where all packages are already cached. That way I take out the
network operations latency out of the measurement.
Giuseppe is also looking to cut down on number of iops done on the disk. He
is complaining that often in cloud their VMs are throttled if they cross
the limit. This option can help them where they reduce number of iops (by
cutting down on frequent sync and writebacks).
Signed-off-by: Giuseppe Scrivano <gscrivan@redhat.com>
Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
An incompatible feature is marked by a non-empty directory nested
2 levels deep under "work" dir, e.g.:
workdir/work/incompat/volatile.
This commit checks for marked incompat features, warns about them
and fails to mount the overlay, for example:
overlayfs: overlay with incompat feature 'volatile' cannot be mounted
Very old kernels (i.e. v3.18) will fail to remove a non-empty "work"
dir and fail the mount. Newer kernels will fail to remove a "work"
dir with entries nested 3 levels and fall back to read-only mount.
User mounting with old kernel will see a warning like these in dmesg:
overlayfs: cleanup of 'incompat/...' failed (-39)
overlayfs: cleanup of 'work/incompat' failed (-39)
overlayfs: cleanup of 'ovl-work/work' failed (-39)
overlayfs: failed to create directory /vdf/ovl-work/work (errno: 17);
mounting read-only
These warnings should give the hint to the user that:
1. mount failure is caused by backward incompatible features
2. mount failure can be resolved by manually removing the "work" directory
There is nothing preventing users on old kernels from manually removing
workdir entirely or mounting overlay with a new workdir, so this is in
no way a full proof backward compatibility enforcement, but only a best
effort.
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Using uninitialized_var() is dangerous as it papers over real bugs[1]
(or can in the future), and suppresses unrelated compiler warnings
(e.g. "unused variable"). If the compiler thinks it is uninitialized,
either simply initialize the variable or make compiler changes.
In preparation for removing[2] the[3] macro[4], remove all remaining
needless uses with the following script:
git grep '\buninitialized_var\b' | cut -d: -f1 | sort -u | \
xargs perl -pi -e \
's/\buninitialized_var\(([^\)]+)\)/\1/g;
s:\s*/\* (GCC be quiet|to make compiler happy) \*/$::g;'
drivers/video/fbdev/riva/riva_hw.c was manually tweaked to avoid
pathological white-space.
No outstanding warnings were found building allmodconfig with GCC 9.3.0
for x86_64, i386, arm64, arm, powerpc, powerpc64le, s390x, mips, sparc64,
alpha, and m68k.
[1] https://lore.kernel.org/lkml/20200603174714.192027-1-glider@google.com/
[2] https://lore.kernel.org/lkml/CA+55aFw+Vbj0i=1TGqCR5vQkCzWJ0QxK6CernOU6eedsudAixw@mail.gmail.com/
[3] https://lore.kernel.org/lkml/CA+55aFwgbgqhbp1fkxvRKEpzyR5J8n1vKT1VZdz9knmPuXhOeg@mail.gmail.com/
[4] https://lore.kernel.org/lkml/CA+55aFz2500WfbKXAx8s67wrm9=yVJu65TpLgN_ybYNv0VEOKA@mail.gmail.com/
Reviewed-by: Leon Romanovsky <leonro@mellanox.com> # drivers/infiniband and mlx4/mlx5
Acked-by: Jason Gunthorpe <jgg@mellanox.com> # IB
Acked-by: Kalle Valo <kvalo@codeaurora.org> # wireless drivers
Reviewed-by: Chao Yu <yuchao0@huawei.com> # erofs
Signed-off-by: Kees Cook <keescook@chromium.org>
We recently moved setting inode flag OVL_UPPERDATA to ovl_lookup().
When looking up an overlay dentry, upperdentry may be found by index
and not by name. In that case, we fail to read the metacopy xattr
and falsly set the OVL_UPPERDATA on the overlay inode.
This caused a regression in xfstest overlay/033 when run with
OVERLAY_MOUNT_OPTIONS="-o metacopy=on".
Fixes: 28166ab3c8 ("ovl: initialize OVL_UPPERDATA in ovl_lookup()")
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
The check if user has changed the overlay file was wrong, causing unneeded
call to ovl_change_flags() including taking f_lock on every file access.
Fixes: d989903058 ("ovl: do not generate duplicate fsnotify events for "fake" path")
Cc: <stable@vger.kernel.org> # v4.19+
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Without upperdir mount option, there is no index dir and the dependency
checks nfs_export => index for mount options parsing are incorrect.
Allow the combination nfs_export=on,index=off with no upperdir and move
the check for dependency redirect_dir=nofollow for non-upper mount case
to mount options parsing.
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
With index feature enabled, on failure to create index dir, overlay is
being mounted read-only. However, we do not forbid user to remount overlay
read-write. Fix that by setting ofs->workdir to NULL, which prevents
remount read-write.
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Commit 9df085f3c9 ("ovl: relax requirement for non null uuid of lower
fs") relaxed the requirement for non null uuid with single lower layer to
allow enabling index and nfs_export features with single lower squashfs.
Fabian reported a regression in a setup when overlay re-uses an existing
upper layer and re-formats the lower squashfs image. Because squashfs
has no uuid, the origin xattr in upper layer are decoded from the new
lower layer where they may resolve to a wrong origin file and user may
get an ESTALE or EIO error on lookup.
To avoid the reported regression while still allowing the new features
with single lower squashfs, do not allow decoding origin with lower null
uuid unless user opted-in to one of the new features that require
following the lower inode of non-dir upper (index, xino, metacopy).
Reported-by: Fabian <godi.beat@gmx.net>
Link: https://lore.kernel.org/linux-unionfs/32532923.JtPX5UtSzP@fgdesktop/
Fixes: 9df085f3c9 ("ovl: relax requirement for non null uuid of lower fs")
Cc: stable@vger.kernel.org # v4.20+
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Mounting with nfs_export=on, xfstests overlay/031 triggers a kernel panic
since v5.8-rc1 overlayfs updates.
overlayfs: orphan index entry (index/00fb1..., ftype=4000, nlink=2)
BUG: kernel NULL pointer dereference, address: 0000000000000030
RIP: 0010:ovl_cleanup_and_whiteout+0x28/0x220 [overlay]
Bisect point at commit c21c839b84 ("ovl: whiteout inode sharing")
Minimal reproducer:
--------------------------------------------------
rm -rf l u w m
mkdir -p l u w m
mkdir -p l/testdir
touch l/testdir/testfile
mount -t overlay -o lowerdir=l,upperdir=u,workdir=w,nfs_export=on overlay m
echo 1 > m/testdir/testfile
umount m
rm -rf u/testdir
mount -t overlay -o lowerdir=l,upperdir=u,workdir=w,nfs_export=on overlay m
umount m
--------------------------------------------------
When mount with nfs_export=on, and fail to verify an orphan index, we're
cleaning this index from indexdir by calling ovl_cleanup_and_whiteout().
This dereferences ofs->workdir, that was earlier set to NULL.
The design was that ovl->workdir will point at ovl->indexdir, but we are
assigning ofs->indexdir to ofs->workdir only after ovl_indexdir_cleanup().
There is no reason not to do it sooner, because once we get success from
ofs->indexdir = ovl_workdir_create(... there is no turning back.
Reported-and-tested-by: Murphy Zhou <jencce.kernel@gmail.com>
Fixes: c21c839b84 ("ovl: whiteout inode sharing")
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Decoding a lower directory file handle to overlay path with cold
inode/dentry cache may go as follows:
1. Decode real lower file handle to lower dir path
2. Check if lower dir is indexed (was copied up)
3. If indexed, get the upper dir path from index
4. Lookup upper dir path in overlay
5. If overlay path found, verify that overlay lower is the lower dir
from step 1
On failure to verify step 5 above, user will get an ESTALE error and a
WARN_ON will be printed.
A mismatch in step 5 could be a result of lower directory that was renamed
while overlay was offline, after that lower directory has been copied up
and indexed.
This is a scripted reproducer based on xfstest overlay/052:
# Create lower subdir
create_dirs
create_test_files $lower/lowertestdir/subdir
mount_dirs
# Copy up lower dir and encode lower subdir file handle
touch $SCRATCH_MNT/lowertestdir
test_file_handles $SCRATCH_MNT/lowertestdir/subdir -p -o $tmp.fhandle
# Rename lower dir offline
unmount_dirs
mv $lower/lowertestdir $lower/lowertestdir.new/
mount_dirs
# Attempt to decode lower subdir file handle
test_file_handles $SCRATCH_MNT -p -i $tmp.fhandle
Since this WARN_ON() can be triggered by user we need to relax it.
Fixes: 4b91c30a5a ("ovl: lookup connected ancestor of dir in inode cache")
Cc: <stable@vger.kernel.org> # v4.16+
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
ovl_check_origin outparam 'ctrp' argument not used by caller. So remove
this argument.
Signed-off-by: youngjun <her0gyugyu@gmail.com>
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
"ovl_copy_up_flags" is used in copy_up.c.
so, change it static.
Signed-off-by: youngjun <her0gyugyu@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
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Merge tag 'ovl-update-5.8' of git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/vfs
Pull overlayfs updates from Miklos Szeredi:
"Fixes:
- Resolve mount option conflicts consistently
- Sync before remount R/O
- Fix file handle encoding corner cases
- Fix metacopy related issues
- Fix an unintialized return value
- Add missing permission checks for underlying layers
Optimizations:
- Allow multipe whiteouts to share an inode
- Optimize small writes by inheriting SB_NOSEC from upper layer
- Do not call ->syncfs() multiple times for sync(2)
- Do not cache negative lookups on upper layer
- Make private internal mounts longterm"
* tag 'ovl-update-5.8' of git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/vfs: (27 commits)
ovl: remove unnecessary lock check
ovl: make oip->index bool
ovl: only pass ->ki_flags to ovl_iocb_to_rwf()
ovl: make private mounts longterm
ovl: get rid of redundant members in struct ovl_fs
ovl: add accessor for ofs->upper_mnt
ovl: initialize error in ovl_copy_xattr
ovl: drop negative dentry in upper layer
ovl: check permission to open real file
ovl: call secutiry hook in ovl_real_ioctl()
ovl: verify permissions in ovl_path_open()
ovl: switch to mounter creds in readdir
ovl: pass correct flags for opening real directory
ovl: fix redirect traversal on metacopy dentries
ovl: initialize OVL_UPPERDATA in ovl_lookup()
ovl: use only uppermetacopy state in ovl_lookup()
ovl: simplify setting of origin for index lookup
ovl: fix out of bounds access warning in ovl_check_fb_len()
ovl: return required buffer size for file handles
ovl: sync dirty data when remounting to ro mode
...
Directory is always locked until "out_unlock" label. So lock check is not
needed.
Signed-off-by: youngjun <her0gyugyu@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
* Fix performance problems found in dioread_nolock now that it is the
default, caused by transaction leaks.
* Clean up fiemap handling in ext4
* Clean up and refactor multiple block allocator (mballoc) code
* Fix a problem with mballoc with a smaller file systems running out
of blocks because they couldn't properly use blocks that had been
reserved by inode preallocation.
* Fixed a race in ext4_sync_parent() versus rename()
* Simplify the error handling in the extent manipulation code
* Make sure all metadata I/O errors are felected to ext4_ext_dirty()'s and
ext4_make_inode_dirty()'s callers.
* Avoid passing an error pointer to brelse in ext4_xattr_set()
* Fix race which could result to freeing an inode on the dirty last
in data=journal mode.
* Fix refcount handling if ext4_iget() fails
* Fix a crash in generic/019 caused by a corrupted extent node
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Merge tag 'ext4_for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4
Pull ext4 updates from Ted Ts'o:
"A lot of bug fixes and cleanups for ext4, including:
- Fix performance problems found in dioread_nolock now that it is the
default, caused by transaction leaks.
- Clean up fiemap handling in ext4
- Clean up and refactor multiple block allocator (mballoc) code
- Fix a problem with mballoc with a smaller file systems running out
of blocks because they couldn't properly use blocks that had been
reserved by inode preallocation.
- Fixed a race in ext4_sync_parent() versus rename()
- Simplify the error handling in the extent manipulation code
- Make sure all metadata I/O errors are felected to
ext4_ext_dirty()'s and ext4_make_inode_dirty()'s callers.
- Avoid passing an error pointer to brelse in ext4_xattr_set()
- Fix race which could result to freeing an inode on the dirty last
in data=journal mode.
- Fix refcount handling if ext4_iget() fails
- Fix a crash in generic/019 caused by a corrupted extent node"
* tag 'ext4_for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4: (58 commits)
ext4: avoid unnecessary transaction starts during writeback
ext4: don't block for O_DIRECT if IOCB_NOWAIT is set
ext4: remove the access_ok() check in ext4_ioctl_get_es_cache
fs: remove the access_ok() check in ioctl_fiemap
fs: handle FIEMAP_FLAG_SYNC in fiemap_prep
fs: move fiemap range validation into the file systems instances
iomap: fix the iomap_fiemap prototype
fs: move the fiemap definitions out of fs.h
fs: mark __generic_block_fiemap static
ext4: remove the call to fiemap_check_flags in ext4_fiemap
ext4: split _ext4_fiemap
ext4: fix fiemap size checks for bitmap files
ext4: fix EXT4_MAX_LOGICAL_BLOCK macro
add comment for ext4_dir_entry_2 file_type member
jbd2: avoid leaking transaction credits when unreserving handle
ext4: drop ext4_journal_free_reserved()
ext4: mballoc: use lock for checking free blocks while retrying
ext4: mballoc: refactor ext4_mb_good_group()
ext4: mballoc: introduce pcpu seqcnt for freeing PA to improve ENOSPC handling
ext4: mballoc: refactor ext4_mb_discard_preallocations()
...
Overlayfs is using clone_private_mount() to create internal mounts for
underlying layers. These are used for operations requiring a path, such as
dentry_open().
Since these private mounts are not in any namespace they are treated as
short term, "detached" mounts and mntput() involves taking the global
mount_lock, which can result in serious cacheline pingpong.
Make these private mounts longterm instead, which trade the penalty on
mntput() for a slightly longer shutdown time due to an added RCU grace
period when putting these mounts.
Introduce a new helper kern_unmount_many() that can take care of multiple
longterm mounts with a single RCU grace period.
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
ofs->upper_mnt is copied to ->layers[0].mnt and ->layers[0].trap could be
used instead of a separate ->upperdir_trap.
Split the lowerdir option early to get the number of layers, then allocate
the ->layers array, and finally fill the upper and lower layers, as before.
Get rid of path_put_init() in ovl_lower_dir(), since the only caller will
take care of that.
[Colin Ian King] Fix null pointer dereference on null stack pointer on
error return found by Coverity.
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
In ovl_copy_xattr, if all the xattrs to be copied are overlayfs private
xattrs, the copy loop will terminate without assigning anything to the
error variable, thus returning an uninitialized value.
If ovl_copy_xattr is called from ovl_clear_empty, this uninitialized error
value is put into a pointer by ERR_PTR(), causing potential invalid memory
accesses down the line.
This commit initialize error with 0. This is the correct value because when
there's no xattr to copy, because all xattrs are private, ovl_copy_xattr
should succeed.
This bug is discovered with the help of INIT_STACK_ALL and clang.
Signed-off-by: Yuxuan Shui <yshuiv7@gmail.com>
Link: https://bugs.chromium.org/p/chromium/issues/detail?id=1050405
Fixes: 0956254a2d ("ovl: don't copy up opaqueness")
Cc: stable@vger.kernel.org # v4.8
Signed-off-by: Alexander Potapenko <glider@google.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
By moving FIEMAP_FLAG_SYNC handling to fiemap_prep we ensure it is
handled once instead of duplicated, but can still be done under fs locks,
like xfs/iomap intended with its duplicate handling. Also make sure the
error value of filemap_write_and_wait is propagated to user space.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Link: https://lore.kernel.org/r/20200523073016.2944131-8-hch@lst.de
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
No need to pull the fiemap definitions into almost every file in the
kernel build.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Ritesh Harjani <riteshh@linux.ibm.com>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Link: https://lore.kernel.org/r/20200523073016.2944131-5-hch@lst.de
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Negative dentries of upper layer are useless after construction of
overlayfs' own dentry and may keep in the memory long time even after
unmount of overlayfs instance. This patch tries to drop unnecessary
negative dentry of upper layer to effectively reclaim memory.
Signed-off-by: Chengguang Xu <cgxu519@mykernel.net>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Call inode_permission() on real inode before opening regular file on one of
the underlying layers.
In some cases ovl_permission() already checks access to an underlying file,
but it misses the metacopy case, and possibly other ones as well.
Removing the redundant permission check from ovl_permission() should be
considered later.
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Verify LSM permissions for underlying file, since vfs_ioctl() doesn't do
it.
[Stephen Rothwell] export security_file_ioctl
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Check permission before opening a real file.
ovl_path_open() is used by readdir and copy-up routines.
ovl_permission() theoretically already checked copy up permissions, but it
doesn't hurt to re-do these checks during the actual copy-up.
For directory reading ovl_permission() only checks access to topmost
underlying layer. Readdir on a merged directory accesses layers below the
topmost one as well. Permission wasn't checked for these layers.
Note: modifying ovl_permission() to perform this check would be far more
complex and hence more bug prone. The result is less precise permissions
returned in access(2). If this turns out to be an issue, we can revisit
this bug.
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
In preparation for more permission checking, override credentials for
directory operations on the underlying filesystems.
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
The three instances of ovl_path_open() in overlayfs/readdir.c do three
different things:
- pass f_flags from overlay file
- pass O_RDONLY | O_DIRECTORY
- pass just O_RDONLY
The value of f_flags can be (other than O_RDONLY):
O_WRONLY - not possible for a directory
O_RDWR - not possible for a directory
O_CREAT - masked out by dentry_open()
O_EXCL - masked out by dentry_open()
O_NOCTTY - masked out by dentry_open()
O_TRUNC - masked out by dentry_open()
O_APPEND - no effect on directory ops
O_NDELAY - no effect on directory ops
O_NONBLOCK - no effect on directory ops
__O_SYNC - no effect on directory ops
O_DSYNC - no effect on directory ops
FASYNC - no effect on directory ops
O_DIRECT - no effect on directory ops
O_LARGEFILE - ?
O_DIRECTORY - only affects lookup
O_NOFOLLOW - only affects lookup
O_NOATIME - overlay sets this unconditionally in ovl_path_open()
O_CLOEXEC - only affects fd allocation
O_PATH - no effect on directory ops
__O_TMPFILE - not possible for a directory
Fon non-merge directories we use the underlying filesystem's iterate; in
this case honor O_LARGEFILE from the original file to make sure that open
doesn't get rejected.
For merge directories it's safe to pass O_LARGEFILE unconditionally since
userspace will only see the artificial offsets created by overlayfs.
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Amir pointed me to metacopy test cases in unionmount-testsuite and I
decided to run "./run --ov=10 --meta" and it failed while running test
"rename-mass-5.py".
Problem is w.r.t absolute redirect traversal on intermediate metacopy
dentry. We do not store intermediate metacopy dentries and also skip
current loop/layer and move onto lookup in next layer. But at the end of
loop, we have logic to reset "poe" and layer index if currnently looked up
dentry has absolute redirect. We skip all that and that means lookup in
next layer will fail.
Following is simple test case to reproduce this.
- mkdir -p lower upper work merged lower/a lower/b
- touch lower/a/foo.txt
- mount -t overlay -o lowerdir=lower,upperdir=upper,workdir=work,metacopy=on none merged
# Following will create absolute redirect "/a/foo.txt" on upper/b/bar.txt.
- mv merged/a/foo.txt merged/b/bar.txt
# unmount overlay and use upper as lower layer (lower2) for next mount.
- umount merged
- mv upper lower2
- rm -rf work; mkdir -p upper work
- mount -t overlay -o lowerdir=lower2:lower,upperdir=upper,workdir=work,metacopy=on none merged
# Force a metacopy copy-up
- chown bin:bin merged/b/bar.txt
# unmount overlay and use upper as lower layer (lower3) for next mount.
- umount merged
- mv upper lower3
- rm -rf work; mkdir -p upper work
- mount -t overlay -o lowerdir=lower3:lower2:lower,upperdir=upper,workdir=work,metacopy=on none merged
# ls merged/b/bar.txt
ls: cannot access 'bar.txt': Input/output error
Intermediate lower layer (lower2) has metacopy dentry b/bar.txt with
absolute redirect "/a/foo.txt". We skipped redirect processing at the end
of loop which sets poe to roe and sets the appropriate next lower layer
index. And that means lookup failed in next layer.
Fix this by continuing the loop for any intermediate dentries. We still do
not save these at lower stack. With this fix applied unionmount-testsuite,
"./run --ov-10 --meta" now passes.
Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Currently ovl_get_inode() initializes OVL_UPPERDATA flag and for that it
has to call ovl_check_metacopy_xattr() and check if metacopy xattr is
present or not.
yangerkun reported sometimes underlying filesystem might return -EIO and in
that case error handling path does not cleanup properly leading to various
warnings.
Run generic/461 with ext4 upper/lower layer sometimes may trigger the bug
as below(linux 4.19):
[ 551.001349] overlayfs: failed to get metacopy (-5)
[ 551.003464] overlayfs: failed to get inode (-5)
[ 551.004243] overlayfs: cleanup of 'd44/fd51' failed (-5)
[ 551.004941] overlayfs: failed to get origin (-5)
[ 551.005199] ------------[ cut here ]------------
[ 551.006697] WARNING: CPU: 3 PID: 24674 at fs/inode.c:1528 iput+0x33b/0x400
...
[ 551.027219] Call Trace:
[ 551.027623] ovl_create_object+0x13f/0x170
[ 551.028268] ovl_create+0x27/0x30
[ 551.028799] path_openat+0x1a35/0x1ea0
[ 551.029377] do_filp_open+0xad/0x160
[ 551.029944] ? vfs_writev+0xe9/0x170
[ 551.030499] ? page_counter_try_charge+0x77/0x120
[ 551.031245] ? __alloc_fd+0x160/0x2a0
[ 551.031832] ? do_sys_open+0x189/0x340
[ 551.032417] ? get_unused_fd_flags+0x34/0x40
[ 551.033081] do_sys_open+0x189/0x340
[ 551.033632] __x64_sys_creat+0x24/0x30
[ 551.034219] do_syscall_64+0xd5/0x430
[ 551.034800] entry_SYSCALL_64_after_hwframe+0x44/0xa9
One solution is to improve error handling and call iget_failed() if error
is encountered. Amir thinks that this path is little intricate and there
is not real need to check and initialize OVL_UPPERDATA in ovl_get_inode().
Instead caller of ovl_get_inode() can initialize this state. And this will
avoid double checking of metacopy xattr lookup in ovl_lookup() and
ovl_get_inode().
OVL_UPPERDATA is inode flag. So I was little concerned that initializing
it outside ovl_get_inode() might have some races. But this is one way
transition. That is once a file has been fully copied up, it can't go back
to metacopy file again. And that seems to help avoid races. So as of now
I can't see any races w.r.t OVL_UPPERDATA being set wrongly. So move
settingof OVL_UPPERDATA inside the callers of ovl_get_inode().
ovl_obtain_alias() already does it. So only two callers now left are
ovl_lookup() and ovl_instantiate().
Reported-by: yangerkun <yangerkun@huawei.com>
Suggested-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Currently we use a variable "metacopy" which signifies that dentry could be
either uppermetacopy or lowermetacopy. Amir suggested that we can move
code around and use d.metacopy in such a way that we don't need
lowermetacopy and just can do away with uppermetacopy.
So this patch replaces "metacopy" with "uppermetacopy".
It also moves some code little higher to keep reading little simpler.
Suggested-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
overlayfs can keep index of copied up files and directories and it seems to
serve two primary puroposes. For regular files, it avoids breaking lower
hardlinks over copy up. For directories it seems to be used for various
error checks.
During ovl_lookup(), we lookup for index using lower dentry in many a
cases. That lower dentry is called "origin" and following is a summary of
current logic.
If there is no upperdentry, always lookup for index using lower dentry.
For regular files it helps avoiding breaking hard links over copyup and for
directories it seems to be just error checks.
If there is an upperdentry, then there are 3 possible cases.
- For directories, lower dentry is found using two ways. One is regular
path based lookup in lower layers and second is using ORIGIN xattr on
upper dentry. First verify that path based lookup lower dentry matches
the one pointed by upper ORIGIN xattr. If yes, use this verified origin
for index lookup.
- For regular files (non-metacopy), there is no path based lookup in lower
layers as lookup stops once we find upper dentry. So there is no origin
verification. If there is ORIGIN xattr present on upper, use that to
lookup index otherwise don't.
- For regular metacopy files, again lower dentry is found using path based
lookup as well as ORIGIN xattr on upper. Path based lookup is continued
in this case to find lower data dentry for metacopy upper. So like
directories we only use verified origin. If ORIGIN xattr is not present
(Either because lower did not support file handles or because this is
hardlink copied up with index=off), then don't use path lookup based
lower dentry as origin. This is same as regular non-metacopy file case.
Suggested-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
