to #23113286

Since the stacking of regular file operations [1], the overlayfs edition of
write_iter() is called when writing regular files.

Since then, xattr lookup is needed on every write since file_remove_privs()
is called from ovl_write_iter(), which would become the performance
bottleneck when writing small chunks of data. In my test case,
file_remove_privs() would consume ~15% CPU when running fstime of unixbench
(the workload is repeadly writing 1 KB to the same file) [2].

Inherit the SB_NOSEC flag from upperdir. Since then xattr lookup would be
done only once on the first write. Unixbench fstime gets a ~20% performance
gain with this patch.

[1] https://lore.kernel.org/lkml/20180606150905.GC9426@magnolia/T/
[2] https://www.spinics.net/lists/linux-unionfs/msg07153.htmlSigned-off-by: NJeffle Xu <jefflexu@linux.alibaba.com>
Signed-off-by: NMiklos Szeredi <mszeredi@redhat.com>
Link: https://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/vfs.git/commit/?h=overlayfs-next&id=b6dee44c57c785a59ef5f1f71588d13ebd89d395Acked-by: NJoseph Qi <joseph.qi@linux.alibaba.com>

A performance regression is observed since linux v4.19 when we do aio
test using fio with iodepth 128 on overlayfs. And we found that queue
depth of the device is always 1 which is unexpected.

After investigation, it is found that commit 16914e6f
("ovl: add ovl_read_iter()") and commit 2a92e07e
("ovl: add ovl_write_iter()") use do_iter_readv_writev() to submit
requests to real filesystem. Async IOs are converted to sync IOs here
and cause performance regression.

So implement async IO for stacked reading and writing.

Changes since v1:
  - add a cleanup helper for completion/error handling
  - handle the case when aio_req allocation failed
Signed-off-by: NJiufei Xue <jiufei.xue@linux.alibaba.com>
Reviewed-by: NJoseph Qi <joseph.qi@linux.alibaba.com>

commit 6889ee5a53b8d969aa542047f5ac8acdc0e79a91 upstream.

In ovl_rename(), if new upper is hardlinked to old upper underneath
overlayfs before upper dirs are locked, user will get an ESTALE error
and a WARN_ON will be printed.

Changes to underlying layers while overlayfs is mounted may result in
unexpected behavior, but it shouldn't crash the kernel and it shouldn't
trigger WARN_ON() either, so relax this WARN_ON().

Reported-by: syzbot+bb1836a212e69f8e201a@syzkaller.appspotmail.com
Fixes: 804032fa ("ovl: don't check rename to self")
Cc: <stable@vger.kernel.org> # v4.9+
Signed-off-by: NAmir Goldstein <amir73il@gmail.com>
Signed-off-by: NMiklos Szeredi <mszeredi@redhat.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

commit 9c6d8f13e9da10a26ad7f0a020ef86e8ef142835 upstream.

On non-samefs overlay without xino, non pure upper inodes should use a
pseudo_dev assigned to each unique lower fs and pure upper inodes use the
real upper st_dev.

It is fine for an overlay pure upper inode to use the same st_dev;st_ino
values as the real upper inode, because the content of those two different
filesystem objects is always the same.

In this case, however:
 - two filesystems, A and B
 - upper layer is on A
 - lower layer 1 is also on A
 - lower layer 2 is on B

Non pure upper overlay inode, whose origin is in layer 1 will have the same
st_dev;st_ino values as the real lower inode. This may result with a false
positive results of 'diff' between the real lower and copied up overlay
inode.

Fix this by using the upper st_dev;st_ino values in this case.  This breaks
the property of constant st_dev;st_ino across copy up of this case. This
breakage will be fixed by a later patch.

Fixes: 5148626b ("ovl: allocate anon bdev per unique lower fs")
Cc: stable@vger.kernel.org # v4.17+
Signed-off-by: NAmir Goldstein <amir73il@gmail.com>
Signed-off-by: NMiklos Szeredi <mszeredi@redhat.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

commit 5c2e9f346b815841f9bed6029ebcb06415caf640 upstream.

When filtering xattr list for reading, presence of trusted xattr
results in a security audit log.  However, if there is other content
no errno will be set, and if there isn't, the errno will be -ENODATA
and not -EPERM as is usually associated with a lack of capability.
The check does not block the request to list the xattrs present.

Switch to ns_capable_noaudit to reflect a more appropriate check.
Signed-off-by: NMark Salyzyn <salyzyn@android.com>
Cc: linux-security-module@vger.kernel.org
Cc: kernel-team@android.com
Cc: stable@vger.kernel.org # v3.18+
Fixes: a082c6f6 ("ovl: filter trusted xattr for non-admin")
Signed-off-by: NMiklos Szeredi <mszeredi@redhat.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

commit 97f024b9171e74c4443bbe8a8dce31b917f97ac5 upstream.

if ovl_encode_real_fh() fails, no memory was allocated
and the error in the error-valued pointer should be returned.

Fixes: 9b6faee0 ("ovl: check ERR_PTR() return value from ovl_encode_fh()")
Signed-off-by: NDing Xiang <dingxiang@cmss.chinamobile.com>
Cc: <stable@vger.kernel.org> # v4.16+
Signed-off-by: NMiklos Szeredi <mszeredi@redhat.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

commit 0be0bfd2de9dfdd2098a9c5b14bdd8f739c9165d upstream.

Once upon a time, commit 2cac0c00 ("ovl: get exclusive ownership on
upper/work dirs") in v4.13 added some sanity checks on overlayfs layers.
This change caused a docker regression. The root cause was mount leaks
by docker, which as far as I know, still exist.

To mitigate the regression, commit 85fdee1e ("ovl: fix regression
caused by exclusive upper/work dir protection") in v4.14 turned the
mount errors into warnings for the default index=off configuration.

Recently, commit 146d62e5a586 ("ovl: detect overlapping layers") in
v5.2, re-introduced exclusive upper/work dir checks regardless of
index=off configuration.

This changes the status quo and mount leak related bug reports have
started to re-surface. Restore the status quo to fix the regressions.
To clarify, index=off does NOT relax overlapping layers check for this
ovelayfs mount. index=off only relaxes exclusive upper/work dir checks
with another overlayfs mount.

To cover the part of overlapping layers detection that used the
exclusive upper/work dir checks to detect overlap with self upper/work
dir, add a trap also on the work base dir.

Link: https://github.com/moby/moby/issues/34672
Link: https://lore.kernel.org/linux-fsdevel/20171006121405.GA32700@veci.piliscsaba.szeredi.hu/
Link: https://github.com/containers/libpod/issues/3540
Fixes: 146d62e5a586 ("ovl: detect overlapping layers")
Cc: <stable@vger.kernel.org> # v4.19+
Signed-off-by: NAmir Goldstein <amir73il@gmail.com>
Tested-by: NColin Walters <walters@verbum.org>
Signed-off-by: NMiklos Szeredi <mszeredi@redhat.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

[ Upstream commit 1dac6f5b0ed2601be21bb4e27a44b0c3e667b7f4 ]

gcc gets a bit confused by the logic in ovl_setup_trap() and
can't figure out whether the local 'trap' variable in the caller
was initialized or not:

fs/overlayfs/super.c: In function 'ovl_fill_super':
fs/overlayfs/super.c:1333:4: error: 'trap' may be used uninitialized in this function [-Werror=maybe-uninitialized]
    iput(trap);
    ^~~~~~~~~~
fs/overlayfs/super.c:1312:17: note: 'trap' was declared here

Reword slightly to make it easier for the compiler to understand.

Fixes: 146d62e5a586 ("ovl: detect overlapping layers")
Signed-off-by: NArnd Bergmann <arnd@arndb.de>
Signed-off-by: NMiklos Szeredi <mszeredi@redhat.com>
Signed-off-by: NSasha Levin <sashal@kernel.org>

[ Upstream commit 9179c21dc6ed1c993caa5fe4da876a6765c26af7 ]

NFS mounts can be disconnected from fs root.  Don't fail the overlapping
layer check because of this.

The check is not authoritative anyway, since topology can change during or
after the check.
Reported-by: NAntti Antinoja <antti@fennosys.fi>
Signed-off-by: NMiklos Szeredi <mszeredi@redhat.com>
Fixes: 146d62e5a586 ("ovl: detect overlapping layers")
Signed-off-by: NSasha Levin <sashal@kernel.org>

[ Upstream commit 146d62e5a5867fbf84490d82455718bfb10fe824 ]

Overlapping overlay layers are not supported and can cause unexpected
behavior, but overlayfs does not currently check or warn about these
configurations.

User is not supposed to specify the same directory for upper and
lower dirs or for different lower layers and user is not supposed to
specify directories that are descendants of each other for overlay
layers, but that is exactly what this zysbot repro did:

    https://syzkaller.appspot.com/x/repro.syz?x=12c7a94f400000

Moving layer root directories into other layers while overlayfs
is mounted could also result in unexpected behavior.

This commit places "traps" in the overlay inode hash table.
Those traps are dummy overlay inodes that are hashed by the layers
root inodes.

On mount, the hash table trap entries are used to verify that overlay
layers are not overlapping.  While at it, we also verify that overlay
layers are not overlapping with directories "in-use" by other overlay
instances as upperdir/workdir.

On lookup, the trap entries are used to verify that overlay layers
root inodes have not been moved into other layers after mount.

Some examples:

$ ./run --ov --samefs -s
...
( mkdir -p base/upper/0/u base/upper/0/w base/lower lower upper mnt
  mount -o bind base/lower lower
  mount -o bind base/upper upper
  mount -t overlay none mnt ...
        -o lowerdir=lower,upperdir=upper/0/u,workdir=upper/0/w)

$ umount mnt
$ mount -t overlay none mnt ...
        -o lowerdir=base,upperdir=upper/0/u,workdir=upper/0/w

  [   94.434900] overlayfs: overlapping upperdir path
  mount: mount overlay on mnt failed: Too many levels of symbolic links

$ mount -t overlay none mnt ...
        -o lowerdir=upper/0/u,upperdir=upper/0/u,workdir=upper/0/w

  [  151.350132] overlayfs: conflicting lowerdir path
  mount: none is already mounted or mnt busy

$ mount -t overlay none mnt ...
        -o lowerdir=lower:lower/a,upperdir=upper/0/u,workdir=upper/0/w

  [  201.205045] overlayfs: overlapping lowerdir path
  mount: mount overlay on mnt failed: Too many levels of symbolic links

$ mount -t overlay none mnt ...
        -o lowerdir=lower,upperdir=upper/0/u,workdir=upper/0/w
$ mv base/upper/0/ base/lower/
$ find mnt/0
  mnt/0
  mnt/0/w
  find: 'mnt/0/w/work': Too many levels of symbolic links
  find: 'mnt/0/u': Too many levels of symbolic links

Reported-by: syzbot+9c69c282adc4edd2b540@syzkaller.appspotmail.com
Signed-off-by: NAmir Goldstein <amir73il@gmail.com>
Signed-off-by: NMiklos Szeredi <mszeredi@redhat.com>
Signed-off-by: NSasha Levin <sashal@kernel.org>

[ Upstream commit 6dde1e42f497b2d4e22466f23019016775607947 ]

Relax the condition that overlayfs supports nfs export, to require
that i_ino is consistent with st_ino/d_ino.

It is enough to require that st_ino and d_ino are consistent.

This fixes the failure of xfstest generic/504, due to mismatch of
st_ino to inode number in the output of /proc/locks.

Fixes: 12574a9f ("ovl: consistent i_ino for non-samefs with xino")
Cc: <stable@vger.kernel.org> # v4.19
Signed-off-by: NAmir Goldstein <amir73il@gmail.com>
Signed-off-by: NMiklos Szeredi <mszeredi@redhat.com>
Signed-off-by: NSasha Levin <sashal@kernel.org>

[ Upstream commit 941d935ac7636911a3fd8fa80e758e52b0b11e20 ]

The ioctl argument was parsed as the wrong type.

Fixes: b21d9c435f93 ("ovl: support the FS_IOC_FS[SG]ETXATTR ioctls")
Signed-off-by: NAmir Goldstein <amir73il@gmail.com>
Signed-off-by: NMiklos Szeredi <mszeredi@redhat.com>
Signed-off-by: NSasha Levin <sashal@kernel.org>

[ Upstream commit b21d9c435f935014d3e3fa6914f2e4fbabb0e94d ]

They are the extended version of FS_IOC_FS[SG]ETFLAGS ioctls.
xfs_io -c "chattr <flags>" uses the new ioctls for setting flags.

This used to work in kernel pre v4.19, before stacked file ops
introduced the ovl_ioctl whitelist.
Reported-by: NDave Chinner <david@fromorbit.com>
Fixes: d1d04ef8 ("ovl: stack file ops")
Cc: <stable@vger.kernel.org> # v4.19
Signed-off-by: NAmir Goldstein <amir73il@gmail.com>
Signed-off-by: NMiklos Szeredi <mszeredi@redhat.com>
Signed-off-by: NSasha Levin <sashal@kernel.org>

commit 9e46b840c7053b5f7a245e98cd239b60d189a96c upstream.

Overlay file f_pos is the master copy that is preserved
through copy up and modified on read/write, but only real
fs knows how to SEEK_HOLE/SEEK_DATA and real fs may impose
limitations that are more strict than ->s_maxbytes for specific
files, so we use the real file to perform seeks.

We do not call real fs for SEEK_CUR:0 query and for SEEK_SET:0
requests.

Fixes: d1d04ef8 ("ovl: stack file ops")
Reported-by: NEddie Horng <eddiehorng.tw@gmail.com>
Signed-off-by: NAmir Goldstein <amir73il@gmail.com>
Signed-off-by: NMiklos Szeredi <mszeredi@redhat.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

commit 98487de318a6f33312471ae1e2afa16fbf8361fe upstream.

We found that it return success when we set IMMUTABLE_FL flag to a file in
docker even though the docker didn't have the capability
CAP_LINUX_IMMUTABLE.

The commit d1d04ef8 ("ovl: stack file ops") and dab5ca8f ("ovl: add
lsattr/chattr support") implemented chattr operations on a regular overlay
file. ovl_real_ioctl() overridden the current process's subjective
credentials with ofs->creator_cred which have the capability
CAP_LINUX_IMMUTABLE so that it will return success in
vfs_ioctl()->cap_capable().

Fix this by checking the capability before cred overridden. And here we
only care about APPEND_FL and IMMUTABLE_FL, so get these information from
inode.

[SzM: move check and call to underlying fs inside inode locked region to
prevent two such calls from racing with each other]
Signed-off-by: NJiufei Xue <jiufei.xue@linux.alibaba.com>
Signed-off-by: NMiklos Szeredi <mszeredi@redhat.com>
Cc: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

[ Upstream commit d989903058a83e8536cc7aadf9256a47d5c173fe ]

Overlayfs "fake" path is used for stacked file operations on underlying
files.  Operations on files with "fake" path must not generate fsnotify
events with path data, because those events have already been generated at
overlayfs layer and because the reported event->fd for fanotify marks on
underlying inode/filesystem will have the wrong path (the overlayfs path).

Link: https://lore.kernel.org/linux-fsdevel/20190423065024.12695-1-jencce.kernel@gmail.com/Reported-by: NMurphy Zhou <jencce.kernel@gmail.com>
Fixes: d1d04ef8 ("ovl: stack file ops")
Signed-off-by: NAmir Goldstein <amir73il@gmail.com>
Signed-off-by: NMiklos Szeredi <mszeredi@redhat.com>
Signed-off-by: NSasha Levin <sashal@kernel.org>

commit acf3062a7e1ccf67c6f7e7c28671a6708fde63b0 upstream.

This nasty little syzbot repro:
https://syzkaller.appspot.com/x/repro.syz?x=12c7a94f400000

Creates overlay mounts where the same directory is both in upper and lower
layers. Simplified example:

  mkdir foo work
  mount -t overlay none foo -o"lowerdir=.,upperdir=foo,workdir=work"

The repro runs several threads in parallel that attempt to chdir into foo
and attempt to symlink/rename/exec/mkdir the file bar.

The repro hits a WARN_ON() I placed in ovl_instantiate(), which suggests
that an overlay inode already exists in cache and is hashed by the pointer
of the real upper dentry that ovl_create_real() has just created. At the
point of the WARN_ON(), for overlay dir inode lock is held and upper dir
inode lock, so at first, I did not see how this was possible.

On a closer look, I see that after ovl_create_real(), because of the
overlapping upper and lower layers, a lookup by another thread can find the
file foo/bar that was just created in upper layer, at overlay path
foo/foo/bar and hash the an overlay inode with the new real dentry as lower
dentry. This is possible because the overlay directory foo/foo is not
locked and the upper dentry foo/bar is in dcache, so ovl_lookup() can find
it without taking upper dir inode shared lock.

Overlapping layers is considered a wrong setup which would result in
unexpected behavior, but it shouldn't crash the kernel and it shouldn't
trigger WARN_ON() either, so relax this WARN_ON() and leave a pr_warn()
instead to cover all cases of failure to get an overlay inode.

The error returned from failure to insert new inode to cache with
inode_insert5() was changed to -EEXIST, to distinguish from the error
-ENOMEM returned on failure to get/allocate inode with iget5_locked().

Reported-by: syzbot+9c69c282adc4edd2b540@syzkaller.appspotmail.com
Fixes: 01b39dcc ("ovl: use inode_insert5() to hash a newly...")
Signed-off-by: NAmir Goldstein <amir73il@gmail.com>
Signed-off-by: NMiklos Szeredi <mszeredi@redhat.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

commit 3428030da004a1128cbdcf93dc03e16f184d845b upstream.

Generalize the helper ovl_open_maybe_copy_up() and use it to copy up file
with data before FS_IOC_SETFLAGS ioctl.

The FS_IOC_SETFLAGS ioctl is a bit of an odd ball in vfs, which probably
caused the confusion.  File may be open O_RDONLY, but ioctl modifies the
file.  VFS does not call mnt_want_write_file() nor lock inode mutex, but
fs-specific code for FS_IOC_SETFLAGS does.  So ovl_ioctl() calls
mnt_want_write_file() for the overlay file, and fs-specific code calls
mnt_want_write_file() for upper fs file, but there was no call for
ovl_want_write() for copy up duration which prevents overlayfs from copying
up on a frozen upper fs.

Fixes: dab5ca8f ("ovl: add lsattr/chattr support")
Cc: <stable@vger.kernel.org> # v4.19
Signed-off-by: NAmir Goldstein <amir73il@gmail.com>
Acked-by: NVivek Goyal <vgoyal@redhat.com>
Signed-off-by: NMiklos Szeredi <mszeredi@redhat.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

commit 993a0b2aec52754f0897b1dab4c453be8217cae5 upstream.

If a file has been copied up metadata only, and later data is copied up,
upper loses any security.capability xattr it has (underlying filesystem
clears it as upon file write).

From a user's point of view, this is just a file copy-up and that should
not result in losing security.capability xattr.  Hence, before data copy
up, save security.capability xattr (if any) and restore it on upper after
data copy up is complete.
Signed-off-by: NVivek Goyal <vgoyal@redhat.com>
Reviewed-by: NAmir Goldstein <amir73il@gmail.com>
Fixes: 0c288874 ("ovl: A new xattr OVL_XATTR_METACOPY for file on upper")
Cc: <stable@vger.kernel.org> # v4.19+
Signed-off-by: NMiklos Szeredi <mszeredi@redhat.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

commit 5f32879ea35523b9842bdbdc0065e13635caada2 upstream.

If a file with capability set (and hence security.capability xattr) is
written kernel clears security.capability xattr. For overlay, during file
copy up if xattrs are copied up first and then data is, copied up. This
means data copy up will result in clearing of security.capability xattr
file on lower has. And this can result into surprises. If a lower file has
CAP_SETUID, then it should not be cleared over copy up (if nothing was
actually written to file).

This also creates problems with chown logic where it first copies up file
and then tries to clear setuid bit. But by that time security.capability
xattr is already gone (due to data copy up), and caller gets -ENODATA.
This has been reported by Giuseppe here.

https://github.com/containers/libpod/issues/2015#issuecomment-447824842

Fix this by copying up data first and then metadta. This is a regression
which has been introduced by my commit as part of metadata only copy up
patches.

TODO: There will be some corner cases where a file is copied up metadata
only and later data copy up happens and that will clear security.capability
xattr. Something needs to be done about that too.

Fixes: bd64e575 ("ovl: During copy up, first copy up metadata and then data")
Cc: <stable@vger.kernel.org> # v4.19+
Reported-by: NGiuseppe Scrivano <gscrivan@redhat.com>
Signed-off-by: NVivek Goyal <vgoyal@redhat.com>
Signed-off-by: NMiklos Szeredi <mszeredi@redhat.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

commit 91ff20f34e94424e586f57f4f593beae16504f86 upstream.

Theodore Ts'o reported a v4.19 regression with docker-dropbox:
https://marc.info/?l=linux-fsdevel&m=154070089431116&w=2

"I was rebuilding my dropbox Docker container, and it failed in 4.19
 with the following error:
 ...
 dpkg: error: error creating new backup file \
              '/var/lib/dpkg/status-old': Invalid cross-device link"

The problem did not reproduce with metacopy feature disabled.
The error was caused by insufficient credentials to set
"trusted.overlay.redirect" xattr on link of a metacopy file.

Reproducer:

 echo Y > /sys/module/overlay/parameters/redirect_dir
 echo Y > /sys/module/overlay/parameters/metacopy
 cd /tmp
 mkdir l u w m
 chmod 777 l u
 touch l/foo
 ln l/foo l/link
 chmod 666 l/foo
 mount -t overlay none -olowerdir=l,upperdir=u,workdir=w m
 su fsgqa
 ln m/foo m/bar
 [   21.455823] overlayfs: failed to set redirect (-1)
 ln: failed to create hard link 'm/bar' => 'm/foo':\
     Invalid cross-device link
Reported-by: NTheodore Y. Ts'o <tytso@mit.edu>
Reported-by: NMaciej Zięba <maciekz82@gmail.com>
Fixes: 4120fe64 ("ovl: Set redirect on upper inode when it is linked")
Cc: <stable@vger.kernel.org> # v4.19
Signed-off-by: NAmir Goldstein <amir73il@gmail.com>
Acked-by: NVivek Goyal <vgoyal@redhat.com>
Signed-off-by: NMiklos Szeredi <mszeredi@redhat.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

commit 155b8a0492a90a4c6e22f046a3568b92a6bc48da upstream.

When decoding a lower file handle, we first call ovl_check_origin_fh()
with connected=false to get any real lower dentry for overlay inode
cache lookup.

If the real dentry is a disconnected dir dentry, ovl_check_origin_fh()
is called again with connected=true to get a connected real dentry
and find the lower layer the real dentry belongs to.

If the first call returned a connected real dentry, we use it to
lookup an overlay connected dentry, but the first ovl_check_origin_fh()
call with connected=false did not check that the found dentry is under
the root of the layer (see ovl_acceptable()), it only checked that
the found dentry super block matches the uuid of the lower file handle.

In case there are multiple lower layers on the same fs and the found
dentry is not from the top most lower layer, using the layer index
returned from the first ovl_check_origin_fh() is wrong and we end
up failing to decode the file handle.

Fix this by always calling ovl_check_origin_fh() with connected=true
if we got a directory dentry in the first call.

Fixes: 8b58924a ("ovl: lookup in inode cache first when decoding...")
Cc: <stable@vger.kernel.org> # v4.17
Signed-off-by: NAmir Goldstein <amir73il@gmail.com>
Signed-off-by: NMiklos Szeredi <mszeredi@redhat.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

commit d47748e5ae5af6572e520cc9767bbe70c22ea498 upstream.

Current behavior is to automatically disable metacopy if redirect_dir is
not enabled and proceed with the mount.

If "metacopy=on" mount option was given, then this behavior can confuse the
user: no mount failure, yet metacopy is disabled.

This patch makes metacopy=on imply redirect_dir=on.

The converse is also true: turning off full redirect with redirect_dir=
{off|follow|nofollow} will disable metacopy.

If both metacopy=on and redirect_dir={off|follow|nofollow} is specified,
then mount will fail, since there's no way to correctly resolve the
conflict.
Reported-by: NDaniel Walsh <dwalsh@redhat.com>
Fixes: d5791044 ("ovl: Provide a mount option metacopy=on/off...")
Cc: <stable@vger.kernel.org> # v4.19
Signed-off-by: NMiklos Szeredi <mszeredi@redhat.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

commit 5e1275808630ea3b2c97c776f40e475017535f72 upstream.

Kaixuxia repors that it's possible to crash overlayfs by removing the
whiteout on the upper layer before creating a directory over it.  This is a
reproducer:

 mkdir lower upper work merge
 touch lower/file
 mount -t overlay overlay -olowerdir=lower,upperdir=upper,workdir=work merge
 rm merge/file
 ls -al merge/file
 rm upper/file
 ls -al merge/
 mkdir merge/file

Before commencing with a vfs_rename(..., RENAME_EXCHANGE) verify that the
lookup of "upper" is positive and is a whiteout, and return ESTALE
otherwise.

Reported by: kaixuxia <xiakaixu1987@gmail.com>
Signed-off-by: NMiklos Szeredi <mszeredi@redhat.com>
Fixes: e9be9d5e ("overlay filesystem")
Cc: <stable@vger.kernel.org> # v3.18
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

commit 6cd078702f2f33cb6b19a682de3e9184112f1a46 upstream.

linking a non-copied-up file into a non-copied-up parent results in a
nested call to mutex_lock_interruptible(&oi->lock). Fix this by copying up
target parent before ovl_nlink_start(), same as done in ovl_rename().

~/unionmount-testsuite$ ./run --ov -s
~/unionmount-testsuite$ ln /mnt/a/foo100 /mnt/a/dir100/

 WARNING: possible recursive locking detected
 --------------------------------------------
 ln/1545 is trying to acquire lock:
 00000000bcce7c4c (&ovl_i_lock_key[depth]){+.+.}, at:
     ovl_copy_up_start+0x28/0x7d
 but task is already holding lock:
 0000000026d73d5b (&ovl_i_lock_key[depth]){+.+.}, at:
     ovl_nlink_start+0x3c/0xc1

[SzM: this seems to be a false positive, but doing the copy-up first is
harmless and removes the lockdep splat]

Reported-by: syzbot+3ef5c0d1a5cb0b21e6be@syzkaller.appspotmail.com
Fixes: 5f8415d6 ("ovl: persistent overlay inode nlink for...")
Cc: <stable@vger.kernel.org> # v4.13
Signed-off-by: NAmir Goldstein <amir73il@gmail.com>
Signed-off-by: NMiklos Szeredi <mszeredi@redhat.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

commit babf4770be0adc69e6d2de150f4040f175e24beb upstream.

We hit a BUG on kfree of an ERR_PTR()...

Reported-by: syzbot+ff03fe05c717b82502d0@syzkaller.appspotmail.com
Fixes: 8b88a2e6 ("ovl: verify upper root dir matches lower root dir")
Cc: <stable@vger.kernel.org> # v4.13
Signed-off-by: NAmir Goldstein <amir73il@gmail.com>
Signed-off-by: NMiklos Szeredi <mszeredi@redhat.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Format has a typo: it was meant to be "%.*s", not "%*s".  But at some point
callers grew nonprintable values as well, so use "%*pE" instead with a
maximized length.
Reported-by: NAmir Goldstein <amir73il@gmail.com>
Signed-off-by: NMiklos Szeredi <mszeredi@redhat.com>
Fixes: 3a1e819b ("ovl: store file handle of lower inode on copy up")
Cc: <stable@vger.kernel.org> # v4.12

KASAN detected slab-out-of-bounds access in printk from overlayfs,
because string format used %*s instead of %.*s.

> BUG: KASAN: slab-out-of-bounds in string+0x298/0x2d0 lib/vsprintf.c:604
> Read of size 1 at addr ffff8801c36c66ba by task syz-executor2/27811
>
> CPU: 0 PID: 27811 Comm: syz-executor2 Not tainted 4.19.0-rc5+ #36
...
>  printk+0xa7/0xcf kernel/printk/printk.c:1996
>  ovl_lookup_index.cold.15+0xe8/0x1f8 fs/overlayfs/namei.c:689

Reported-by: syzbot+376cea2b0ef340db3dd4@syzkaller.appspotmail.com
Signed-off-by: NAmir Goldstein <amir73il@gmail.com>
Signed-off-by: NMiklos Szeredi <mszeredi@redhat.com>
Fixes: 359f392c ("ovl: lookup index entry for copy up origin")
Cc: <stable@vger.kernel.org> # v4.13

Fixes the following sparse warning:

fs/overlayfs/inode.c:507:39: warning:
 symbol 'ovl_aops' was not declared. Should it be static?

Fixes: 5b910bd6 ("ovl: fix GPF in swapfile_activate of file from overlayfs over xfs")
Signed-off-by: NWei Yongjun <weiyongjun1@huawei.com>
Signed-off-by: NMiklos Szeredi <mszeredi@redhat.com>

Commit 031a072a ("vfs: call vfs_clone_file_range() under freeze
protection") created a wrapper do_clone_file_range() around
vfs_clone_file_range() moving the freeze protection to former, so
overlayfs could call the latter.

The more common vfs practice is to call do_xxx helpers from vfs_xxx
helpers, where freeze protecction is taken in the vfs_xxx helper, so
this anomality could be a source of confusion.

It seems that commit 8ede2055 ("ovl: add reflink/copyfile/dedup
support") may have fallen a victim to this confusion -
ovl_clone_file_range() calls the vfs_clone_file_range() helper in the
hope of getting freeze protection on upper fs, but in fact results in
overlayfs allowing to bypass upper fs freeze protection.

Swap the names of the two helpers to conform to common vfs practice
and call the correct helpers from overlayfs and nfsd.
Signed-off-by: NAmir Goldstein <amir73il@gmail.com>
Signed-off-by: NMiklos Szeredi <mszeredi@redhat.com>

Tested by doing clone on overlayfs while upper xfs+reflink is frozen:

  xfs_io -f /ovl/y
                             fsfreeze -f /xfs
  xfs_io> reflink /ovl/x

Before the fix xfs_io enters xfs_reflink_remap_range() and blocks
in xfs_trans_alloc(). After the fix, xfs_io blocks outside xfs code
in ovl_clone_file_range().

Fixes: 8ede2055 ("ovl: add reflink/copyfile/dedup support")
Signed-off-by: NAmir Goldstein <amir73il@gmail.com>
Signed-off-by: NMiklos Szeredi <mszeredi@redhat.com>

Tested by re-writing to an open overlayfs file while upper ext4 is frozen:

  xfs_io -f /ovl/x
  xfs_io> pwrite 0 4096
                             fsfreeze -f /ext4
  xfs_io> pwrite 0 4096

  WARNING: CPU: 0 PID: 1492 at fs/ext4/ext4_jbd2.c:53 \
           ext4_journal_check_start+0x48/0x82

After the fix, the second write blocks in ovl_write_iter() and avoids
hitting WARN_ON(sb->s_writers.frozen == SB_FREEZE_COMPLETE) in
ext4_journal_check_start().

Fixes: 2a92e07e ("ovl: add ovl_write_iter()")
Signed-off-by: NAmir Goldstein <amir73il@gmail.com>
Signed-off-by: NMiklos Szeredi <mszeredi@redhat.com>

The memory leak was detected by kmemleak when running xfstests
overlay/051,053

Fixes: caf70cb2 ("ovl: cleanup orphan index entries")
Cc: <stable@vger.kernel.org> # v4.13
Signed-off-by: NAmir Goldstein <amir73il@gmail.com>
Signed-off-by: NMiklos Szeredi <mszeredi@redhat.com>

ovl_free_fs() dereferences ofs->workbasedir and ofs->upper_mnt in cases when
those might not have been initialized yet.

Fix the initialization order for these fields.

Reported-by: syzbot+c75f181dc8429d2eb887@syzkaller.appspotmail.com
Signed-off-by: NMiklos Szeredi <mszeredi@redhat.com>
Cc:  <stable@vger.kernel.org> # v4.15
Fixes: 95e6d417 ("ovl: grab reference to workbasedir early")
Fixes: a9075cdb ("ovl: factor out ovl_free_fs() helper")

Implement stacked fadvise to fix syscalls readahead(2) and fadvise64(2)
on an overlayfs file.
Suggested-by: NMiklos Szeredi <mszeredi@redhat.com>
Fixes: d1d04ef8 ("ovl: stack file ops")
Signed-off-by: NAmir Goldstein <amir73il@gmail.com>
Signed-off-by: NMiklos Szeredi <mszeredi@redhat.com>

Since overlayfs implements stacked file operations, the underlying
filesystems are not supposed to be exposed to the overlayfs file,
whose f_inode is an overlayfs inode.

Assigning an overlayfs file to swap_file results in an attempt of xfs
code to dereference an xfs_inode struct from an ovl_inode pointer:

 CPU: 0 PID: 2462 Comm: swapon Not tainted
 4.18.0-xfstests-12721-g33e17876 #3402
 RIP: 0010:xfs_find_bdev_for_inode+0x23/0x2f
 Call Trace:
  xfs_iomap_swapfile_activate+0x1f/0x43
  __se_sys_swapon+0xb1a/0xee9

Fix this by not assigning the real inode mapping to f_mapping, which
will cause swapon() to return an error (-EINVAL). Although it makes
sense not to allow setting swpafile on an overlayfs file, some users
may depend on it, so we may need to fix this up in the future.

Keeping f_mapping pointing to overlay inode mapping will cause O_DIRECT
open to fail. Fix this by installing ovl_aops with noop_direct_IO in
overlay inode mapping.

Keeping f_mapping pointing to overlay inode mapping will cause other
a_ops related operations to fail (e.g. readahead()). Those will be
fixed by follow up patches.
Suggested-by: NMiklos Szeredi <mszeredi@redhat.com>
Fixes: f7c72396 ("ovl: add O_DIRECT support")
Signed-off-by: NAmir Goldstein <amir73il@gmail.com>
Signed-off-by: NMiklos Szeredi <mszeredi@redhat.com>

Stacked overlayfs fiemap operation broke xfstests that test delayed
allocation (with "_test_generic_punch -d"), because ovl_fiemap()
failed to write dirty pages when requested.

Fixes: 9e142c41 ("ovl: add ovl_fiemap()")
Signed-off-by: NAmir Goldstein <amir73il@gmail.com>
Signed-off-by: NMiklos Szeredi <mszeredi@redhat.com>

...otherwise there will be list corruption due to inode_sb_list_add() being
called for inode already on the sb list.
Signed-off-by: NMiklos Szeredi <mszeredi@redhat.com>
Fixes: e950564b ("vfs: don't evict uninitialized inode")
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

All the bits are in patches before this.  So it is time to enable the
metadata only copy up feature.
Signed-off-by: NVivek Goyal <vgoyal@redhat.com>
Reviewed-by: NAmir Goldstein <amir73il@gmail.com>
Signed-off-by: NMiklos Szeredi <mszeredi@redhat.com>

ovl_copy_up() by default will only do metadata only copy up (if enabled).
That means when ovl_real_ioctl() calls ovl_real_file(), it will still get
the lower file (as ovl_real_file() opens data file and not metacopy).  And
that means "chattr +i" will end up modifying lower inode.

There seem to be two ways to solve this.
A. Open metacopy file in ovl_real_ioctl() and do operations on that
B. Force full copy up when FS_IOC_SETFLAGS is called.

I am resorting to option B for now as it feels little safer option.  If
there are performance issues due to this, we can revisit it.
Signed-off-by: NVivek Goyal <vgoyal@redhat.com>
Reviewed-by: NAmir Goldstein <amir73il@gmail.com>
Signed-off-by: NMiklos Szeredi <mszeredi@redhat.com>