<feed xmlns='http://www.w3.org/2005/Atom'>
<title>linux-stable.git/fs/ext4, branch v4.4.91</title>
<subtitle>Linux kernel stable tree</subtitle>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/'/>
<entry>
<title>ext4: fix quota inconsistency during orphan cleanup for read-only mounts</title>
<updated>2017-09-27T09:00:14+00:00</updated>
<author>
<name>zhangyi (F)</name>
<email>yi.zhang@huawei.com</email>
</author>
<published>2017-08-24T19:21:50+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=c53f01698f68a3d6880c27e24a4e98ca6cd9feb9'/>
<id>c53f01698f68a3d6880c27e24a4e98ca6cd9feb9</id>
<content type='text'>
commit 95f1fda47c9d8738f858c3861add7bf0a36a7c0b upstream.

Quota does not get enabled for read-only mounts if filesystem
has quota feature, so that quotas cannot updated during orphan
cleanup, which will lead to quota inconsistency.

This patch turn on quotas during orphan cleanup for this case,
make sure quotas can be updated correctly.

Reported-by: Jan Kara &lt;jack@suse.cz&gt;
Signed-off-by: zhangyi (F) &lt;yi.zhang@huawei.com&gt;
Signed-off-by: Theodore Ts'o &lt;tytso@mit.edu&gt;
Reviewed-by: Jan Kara &lt;jack@suse.cz&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;

</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
commit 95f1fda47c9d8738f858c3861add7bf0a36a7c0b upstream.

Quota does not get enabled for read-only mounts if filesystem
has quota feature, so that quotas cannot updated during orphan
cleanup, which will lead to quota inconsistency.

This patch turn on quotas during orphan cleanup for this case,
make sure quotas can be updated correctly.

Reported-by: Jan Kara &lt;jack@suse.cz&gt;
Signed-off-by: zhangyi (F) &lt;yi.zhang@huawei.com&gt;
Signed-off-by: Theodore Ts'o &lt;tytso@mit.edu&gt;
Reviewed-by: Jan Kara &lt;jack@suse.cz&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;

</pre>
</div>
</content>
</entry>
<entry>
<title>ext4: fix incorrect quotaoff if the quota feature is enabled</title>
<updated>2017-09-27T09:00:14+00:00</updated>
<author>
<name>zhangyi (F)</name>
<email>yi.zhang@huawei.com</email>
</author>
<published>2017-08-24T19:19:39+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=cd46241eb03ca90f58553ad15e484c4f86d6fd64'/>
<id>cd46241eb03ca90f58553ad15e484c4f86d6fd64</id>
<content type='text'>
commit b0a5a9589decd07db755d6a8d9c0910d96ff7992 upstream.

Current ext4 quota should always "usage enabled" if the
quota feautre is enabled. But in ext4_orphan_cleanup(), it
turn quotas off directly (used for the older journaled
quota), so we cannot turn it on again via "quotaon" unless
umount and remount ext4.

Simple reproduce:

  mkfs.ext4 -O project,quota /dev/vdb1
  mount -o prjquota /dev/vdb1 /mnt
  chattr -p 123 /mnt
  chattr +P /mnt
  touch /mnt/aa /mnt/bb
  exec 100&lt;&gt;/mnt/aa
  rm -f /mnt/aa
  sync
  echo c &gt; /proc/sysrq-trigger

  #reboot and mount
  mount -o prjquota /dev/vdb1 /mnt
  #query status
  quotaon -Ppv /dev/vdb1
  #output
  quotaon: Cannot find mountpoint for device /dev/vdb1
  quotaon: No correct mountpoint specified.

This patch add check for journaled quotas to avoid incorrect
quotaoff when ext4 has quota feautre.

Signed-off-by: zhangyi (F) &lt;yi.zhang@huawei.com&gt;
Signed-off-by: Theodore Ts'o &lt;tytso@mit.edu&gt;
Reviewed-by: Jan Kara &lt;jack@suse.cz&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;

</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
commit b0a5a9589decd07db755d6a8d9c0910d96ff7992 upstream.

Current ext4 quota should always "usage enabled" if the
quota feautre is enabled. But in ext4_orphan_cleanup(), it
turn quotas off directly (used for the older journaled
quota), so we cannot turn it on again via "quotaon" unless
umount and remount ext4.

Simple reproduce:

  mkfs.ext4 -O project,quota /dev/vdb1
  mount -o prjquota /dev/vdb1 /mnt
  chattr -p 123 /mnt
  chattr +P /mnt
  touch /mnt/aa /mnt/bb
  exec 100&lt;&gt;/mnt/aa
  rm -f /mnt/aa
  sync
  echo c &gt; /proc/sysrq-trigger

  #reboot and mount
  mount -o prjquota /dev/vdb1 /mnt
  #query status
  quotaon -Ppv /dev/vdb1
  #output
  quotaon: Cannot find mountpoint for device /dev/vdb1
  quotaon: No correct mountpoint specified.

This patch add check for journaled quotas to avoid incorrect
quotaoff when ext4 has quota feautre.

Signed-off-by: zhangyi (F) &lt;yi.zhang@huawei.com&gt;
Signed-off-by: Theodore Ts'o &lt;tytso@mit.edu&gt;
Reviewed-by: Jan Kara &lt;jack@suse.cz&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;

</pre>
</div>
</content>
</entry>
<entry>
<title>ext4: fix overflow caused by missing cast in ext4_resize_fs()</title>
<updated>2017-08-11T16:08:48+00:00</updated>
<author>
<name>Jerry Lee</name>
<email>jerrylee@qnap.com</email>
</author>
<published>2017-08-06T05:18:31+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=31cd127ca69a1aedd24b9aa7ac806e6071c84655'/>
<id>31cd127ca69a1aedd24b9aa7ac806e6071c84655</id>
<content type='text'>
commit aec51758ce10a9c847a62a48a168f8c804c6e053 upstream.

On a 32-bit platform, the value of n_blcoks_count may be wrong during
the file system is resized to size larger than 2^32 blocks.  This may
caused the superblock being corrupted with zero blocks count.

Fixes: 1c6bd7173d66
Signed-off-by: Jerry Lee &lt;jerrylee@qnap.com&gt;
Signed-off-by: Theodore Ts'o &lt;tytso@mit.edu&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;

</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
commit aec51758ce10a9c847a62a48a168f8c804c6e053 upstream.

On a 32-bit platform, the value of n_blcoks_count may be wrong during
the file system is resized to size larger than 2^32 blocks.  This may
caused the superblock being corrupted with zero blocks count.

Fixes: 1c6bd7173d66
Signed-off-by: Jerry Lee &lt;jerrylee@qnap.com&gt;
Signed-off-by: Theodore Ts'o &lt;tytso@mit.edu&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;

</pre>
</div>
</content>
</entry>
<entry>
<title>ext4: fix SEEK_HOLE/SEEK_DATA for blocksize &lt; pagesize</title>
<updated>2017-08-11T16:08:48+00:00</updated>
<author>
<name>Jan Kara</name>
<email>jack@suse.cz</email>
</author>
<published>2017-08-05T21:43:24+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=bad9f6142ce1141b7e4969d898cf0e2d61e90d5b'/>
<id>bad9f6142ce1141b7e4969d898cf0e2d61e90d5b</id>
<content type='text'>
commit fcf5ea10992fbac3c7473a1db33d56a139333cd1 upstream.

ext4_find_unwritten_pgoff() does not properly handle a situation when
starting index is in the middle of a page and blocksize &lt; pagesize. The
following command shows the bug on filesystem with 1k blocksize:

  xfs_io -f -c "falloc 0 4k" \
            -c "pwrite 1k 1k" \
            -c "pwrite 3k 1k" \
            -c "seek -a -r 0" foo

In this example, neither lseek(fd, 1024, SEEK_HOLE) nor lseek(fd, 2048,
SEEK_DATA) will return the correct result.

Fix the problem by neglecting buffers in a page before starting offset.

Reported-by: Andreas Gruenbacher &lt;agruenba@redhat.com&gt;
Signed-off-by: Theodore Ts'o &lt;tytso@mit.edu&gt;
Signed-off-by: Jan Kara &lt;jack@suse.cz&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;

</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
commit fcf5ea10992fbac3c7473a1db33d56a139333cd1 upstream.

ext4_find_unwritten_pgoff() does not properly handle a situation when
starting index is in the middle of a page and blocksize &lt; pagesize. The
following command shows the bug on filesystem with 1k blocksize:

  xfs_io -f -c "falloc 0 4k" \
            -c "pwrite 1k 1k" \
            -c "pwrite 3k 1k" \
            -c "seek -a -r 0" foo

In this example, neither lseek(fd, 1024, SEEK_HOLE) nor lseek(fd, 2048,
SEEK_DATA) will return the correct result.

Fix the problem by neglecting buffers in a page before starting offset.

Reported-by: Andreas Gruenbacher &lt;agruenba@redhat.com&gt;
Signed-off-by: Theodore Ts'o &lt;tytso@mit.edu&gt;
Signed-off-by: Jan Kara &lt;jack@suse.cz&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;

</pre>
</div>
</content>
</entry>
<entry>
<title>ext4: check return value of kstrtoull correctly in reserved_clusters_store</title>
<updated>2017-07-15T09:57:50+00:00</updated>
<author>
<name>Chao Yu</name>
<email>yuchao0@huawei.com</email>
</author>
<published>2017-06-23T05:08:22+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=ad5a88c54cd299f3bb2bf53810dd5bb5805369c3'/>
<id>ad5a88c54cd299f3bb2bf53810dd5bb5805369c3</id>
<content type='text'>
commit 1ea1516fbbab2b30bf98c534ecaacba579a35208 upstream.

kstrtoull returns 0 on success, however, in reserved_clusters_store we
will return -EINVAL if kstrtoull returns 0, it makes us fail to update
reserved_clusters value through sysfs.

Fixes: 76d33bca5581b1dd5c3157fa168db849a784ada4
Signed-off-by: Chao Yu &lt;yuchao0@huawei.com&gt;
Signed-off-by: Miao Xie &lt;miaoxie@huawei.com&gt;
Signed-off-by: Theodore Ts'o &lt;tytso@mit.edu&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;

</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
commit 1ea1516fbbab2b30bf98c534ecaacba579a35208 upstream.

kstrtoull returns 0 on success, however, in reserved_clusters_store we
will return -EINVAL if kstrtoull returns 0, it makes us fail to update
reserved_clusters value through sysfs.

Fixes: 76d33bca5581b1dd5c3157fa168db849a784ada4
Signed-off-by: Chao Yu &lt;yuchao0@huawei.com&gt;
Signed-off-by: Miao Xie &lt;miaoxie@huawei.com&gt;
Signed-off-by: Theodore Ts'o &lt;tytso@mit.edu&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;

</pre>
</div>
</content>
</entry>
<entry>
<title>fs: add i_blocksize()</title>
<updated>2017-06-14T11:16:24+00:00</updated>
<author>
<name>Fabian Frederick</name>
<email>fabf@skynet.be</email>
</author>
<published>2017-02-27T22:28:32+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=044470266a5040585093e863f163f49024c3e459'/>
<id>044470266a5040585093e863f163f49024c3e459</id>
<content type='text'>
commit 93407472a21b82f39c955ea7787e5bc7da100642 upstream.

Replace all 1 &lt;&lt; inode-&gt;i_blkbits and (1 &lt;&lt; inode-&gt;i_blkbits) in fs
branch.

This patch also fixes multiple checkpatch warnings: WARNING: Prefer
'unsigned int' to bare use of 'unsigned'

Thanks to Andrew Morton for suggesting more appropriate function instead
of macro.

[geliangtang@gmail.com: truncate: use i_blocksize()]
  Link: http://lkml.kernel.org/r/9c8b2cd83c8f5653805d43debde9fa8817e02fc4.1484895804.git.geliangtang@gmail.com
Link: http://lkml.kernel.org/r/1481319905-10126-1-git-send-email-fabf@skynet.be
Signed-off-by: Fabian Frederick &lt;fabf@skynet.be&gt;
Signed-off-by: Geliang Tang &lt;geliangtang@gmail.com&gt;
Cc: Alexander Viro &lt;viro@zeniv.linux.org.uk&gt;
Cc: Ross Zwisler &lt;ross.zwisler@linux.intel.com&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
Signed-off-by: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;

</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
commit 93407472a21b82f39c955ea7787e5bc7da100642 upstream.

Replace all 1 &lt;&lt; inode-&gt;i_blkbits and (1 &lt;&lt; inode-&gt;i_blkbits) in fs
branch.

This patch also fixes multiple checkpatch warnings: WARNING: Prefer
'unsigned int' to bare use of 'unsigned'

Thanks to Andrew Morton for suggesting more appropriate function instead
of macro.

[geliangtang@gmail.com: truncate: use i_blocksize()]
  Link: http://lkml.kernel.org/r/9c8b2cd83c8f5653805d43debde9fa8817e02fc4.1484895804.git.geliangtang@gmail.com
Link: http://lkml.kernel.org/r/1481319905-10126-1-git-send-email-fabf@skynet.be
Signed-off-by: Fabian Frederick &lt;fabf@skynet.be&gt;
Signed-off-by: Geliang Tang &lt;geliangtang@gmail.com&gt;
Cc: Alexander Viro &lt;viro@zeniv.linux.org.uk&gt;
Cc: Ross Zwisler &lt;ross.zwisler@linux.intel.com&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
Signed-off-by: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;

</pre>
</div>
</content>
</entry>
<entry>
<title>ext4: fix fdatasync(2) after extent manipulation operations</title>
<updated>2017-06-14T11:16:22+00:00</updated>
<author>
<name>Jan Kara</name>
<email>jack@suse.cz</email>
</author>
<published>2017-05-29T17:24:55+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=daa1357ff346a67b68d03e0450de2e87a71d2ddf'/>
<id>daa1357ff346a67b68d03e0450de2e87a71d2ddf</id>
<content type='text'>
commit 67a7d5f561f469ad2fa5154d2888258ab8e6df7c upstream.

Currently, extent manipulation operations such as hole punch, range
zeroing, or extent shifting do not record the fact that file data has
changed and thus fdatasync(2) has a work to do. As a result if we crash
e.g. after a punch hole and fdatasync, user can still possibly see the
punched out data after journal replay. Test generic/392 fails due to
these problems.

Fix the problem by properly marking that file data has changed in these
operations.

Fixes: a4bb6b64e39abc0e41ca077725f2a72c868e7622
Signed-off-by: Jan Kara &lt;jack@suse.cz&gt;
Signed-off-by: Theodore Ts'o &lt;tytso@mit.edu&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;

</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
commit 67a7d5f561f469ad2fa5154d2888258ab8e6df7c upstream.

Currently, extent manipulation operations such as hole punch, range
zeroing, or extent shifting do not record the fact that file data has
changed and thus fdatasync(2) has a work to do. As a result if we crash
e.g. after a punch hole and fdatasync, user can still possibly see the
punched out data after journal replay. Test generic/392 fails due to
these problems.

Fix the problem by properly marking that file data has changed in these
operations.

Fixes: a4bb6b64e39abc0e41ca077725f2a72c868e7622
Signed-off-by: Jan Kara &lt;jack@suse.cz&gt;
Signed-off-by: Theodore Ts'o &lt;tytso@mit.edu&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;

</pre>
</div>
</content>
</entry>
<entry>
<title>ext4: keep existing extra fields when inode expands</title>
<updated>2017-06-14T11:16:22+00:00</updated>
<author>
<name>Konstantin Khlebnikov</name>
<email>khlebnikov@yandex-team.ru</email>
</author>
<published>2017-05-22T02:36:23+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=7b9694cb7bf2fcd2b443807423b4b09fbbc3c4ff'/>
<id>7b9694cb7bf2fcd2b443807423b4b09fbbc3c4ff</id>
<content type='text'>
commit 887a9730614727c4fff7cb756711b190593fc1df upstream.

ext4_expand_extra_isize() should clear only space between old and new
size.

Fixes: 6dd4ee7cab7e # v2.6.23
Signed-off-by: Konstantin Khlebnikov &lt;khlebnikov@yandex-team.ru&gt;
Signed-off-by: Theodore Ts'o &lt;tytso@mit.edu&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;

</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
commit 887a9730614727c4fff7cb756711b190593fc1df upstream.

ext4_expand_extra_isize() should clear only space between old and new
size.

Fixes: 6dd4ee7cab7e # v2.6.23
Signed-off-by: Konstantin Khlebnikov &lt;khlebnikov@yandex-team.ru&gt;
Signed-off-by: Theodore Ts'o &lt;tytso@mit.edu&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;

</pre>
</div>
</content>
</entry>
<entry>
<title>ext4: fix SEEK_HOLE</title>
<updated>2017-06-14T11:16:22+00:00</updated>
<author>
<name>Jan Kara</name>
<email>jack@suse.cz</email>
</author>
<published>2017-05-22T02:33:23+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=08dc390b2745e0eb26375758534f52ce4eb983ae'/>
<id>08dc390b2745e0eb26375758534f52ce4eb983ae</id>
<content type='text'>
commit 7d95eddf313c88b24f99d4ca9c2411a4b82fef33 upstream.

Currently, SEEK_HOLE implementation in ext4 may both return that there's
a hole at some offset although that offset already has data and skip
some holes during a search for the next hole. The first problem is
demostrated by:

xfs_io -c "falloc 0 256k" -c "pwrite 0 56k" -c "seek -h 0" file
wrote 57344/57344 bytes at offset 0
56 KiB, 14 ops; 0.0000 sec (2.054 GiB/sec and 538461.5385 ops/sec)
Whence	Result
HOLE	0

Where we can see that SEEK_HOLE wrongly returned offset 0 as containing
a hole although we have written data there. The second problem can be
demonstrated by:

xfs_io -c "falloc 0 256k" -c "pwrite 0 56k" -c "pwrite 128k 8k"
       -c "seek -h 0" file

wrote 57344/57344 bytes at offset 0
56 KiB, 14 ops; 0.0000 sec (1.978 GiB/sec and 518518.5185 ops/sec)
wrote 8192/8192 bytes at offset 131072
8 KiB, 2 ops; 0.0000 sec (2 GiB/sec and 500000.0000 ops/sec)
Whence	Result
HOLE	139264

Where we can see that hole at offsets 56k..128k has been ignored by the
SEEK_HOLE call.

The underlying problem is in the ext4_find_unwritten_pgoff() which is
just buggy. In some cases it fails to update returned offset when it
finds a hole (when no pages are found or when the first found page has
higher index than expected), in some cases conditions for detecting hole
are just missing (we fail to detect a situation where indices of
returned pages are not contiguous).

Fix ext4_find_unwritten_pgoff() to properly detect non-contiguous page
indices and also handle all cases where we got less pages then expected
in one place and handle it properly there.

Fixes: c8c0df241cc2719b1262e627f999638411934f60
CC: Zheng Liu &lt;wenqing.lz@taobao.com&gt;
Signed-off-by: Jan Kara &lt;jack@suse.cz&gt;
Signed-off-by: Theodore Ts'o &lt;tytso@mit.edu&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;

</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
commit 7d95eddf313c88b24f99d4ca9c2411a4b82fef33 upstream.

Currently, SEEK_HOLE implementation in ext4 may both return that there's
a hole at some offset although that offset already has data and skip
some holes during a search for the next hole. The first problem is
demostrated by:

xfs_io -c "falloc 0 256k" -c "pwrite 0 56k" -c "seek -h 0" file
wrote 57344/57344 bytes at offset 0
56 KiB, 14 ops; 0.0000 sec (2.054 GiB/sec and 538461.5385 ops/sec)
Whence	Result
HOLE	0

Where we can see that SEEK_HOLE wrongly returned offset 0 as containing
a hole although we have written data there. The second problem can be
demonstrated by:

xfs_io -c "falloc 0 256k" -c "pwrite 0 56k" -c "pwrite 128k 8k"
       -c "seek -h 0" file

wrote 57344/57344 bytes at offset 0
56 KiB, 14 ops; 0.0000 sec (1.978 GiB/sec and 518518.5185 ops/sec)
wrote 8192/8192 bytes at offset 131072
8 KiB, 2 ops; 0.0000 sec (2 GiB/sec and 500000.0000 ops/sec)
Whence	Result
HOLE	139264

Where we can see that hole at offsets 56k..128k has been ignored by the
SEEK_HOLE call.

The underlying problem is in the ext4_find_unwritten_pgoff() which is
just buggy. In some cases it fails to update returned offset when it
finds a hole (when no pages are found or when the first found page has
higher index than expected), in some cases conditions for detecting hole
are just missing (we fail to detect a situation where indices of
returned pages are not contiguous).

Fix ext4_find_unwritten_pgoff() to properly detect non-contiguous page
indices and also handle all cases where we got less pages then expected
in one place and handle it properly there.

Fixes: c8c0df241cc2719b1262e627f999638411934f60
CC: Zheng Liu &lt;wenqing.lz@taobao.com&gt;
Signed-off-by: Jan Kara &lt;jack@suse.cz&gt;
Signed-off-by: Theodore Ts'o &lt;tytso@mit.edu&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;

</pre>
</div>
</content>
</entry>
<entry>
<title>fscrypt: avoid collisions when presenting long encrypted filenames</title>
<updated>2017-05-25T12:30:11+00:00</updated>
<author>
<name>Eric Biggers</name>
<email>ebiggers@google.com</email>
</author>
<published>2017-04-24T17:00:09+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=ae3d7b8931eb3151d8ad4fb8be6fe885000d3838'/>
<id>ae3d7b8931eb3151d8ad4fb8be6fe885000d3838</id>
<content type='text'>
commit 6b06cdee81d68a8a829ad8e8d0f31d6836744af9 upstream.

When accessing an encrypted directory without the key, userspace must
operate on filenames derived from the ciphertext names, which contain
arbitrary bytes.  Since we must support filenames as long as NAME_MAX,
we can't always just base64-encode the ciphertext, since that may make
it too long.  Currently, this is solved by presenting long names in an
abbreviated form containing any needed filesystem-specific hashes (e.g.
to identify a directory block), then the last 16 bytes of ciphertext.
This needs to be sufficient to identify the actual name on lookup.

However, there is a bug.  It seems to have been assumed that due to the
use of a CBC (ciphertext block chaining)-based encryption mode, the last
16 bytes (i.e. the AES block size) of ciphertext would depend on the
full plaintext, preventing collisions.  However, we actually use CBC
with ciphertext stealing (CTS), which handles the last two blocks
specially, causing them to appear "flipped".  Thus, it's actually the
second-to-last block which depends on the full plaintext.

This caused long filenames that differ only near the end of their
plaintexts to, when observed without the key, point to the wrong inode
and be undeletable.  For example, with ext4:

    # echo pass | e4crypt add_key -p 16 edir/
    # seq -f "edir/abcdefghijklmnopqrstuvwxyz012345%.0f" 100000 | xargs touch
    # find edir/ -type f | xargs stat -c %i | sort | uniq | wc -l
    100000
    # sync
    # echo 3 &gt; /proc/sys/vm/drop_caches
    # keyctl new_session
    # find edir/ -type f | xargs stat -c %i | sort | uniq | wc -l
    2004
    # rm -rf edir/
    rm: cannot remove 'edir/_A7nNFi3rhkEQlJ6P,hdzluhODKOeWx5V': Structure needs cleaning
    ...

To fix this, when presenting long encrypted filenames, encode the
second-to-last block of ciphertext rather than the last 16 bytes.

Although it would be nice to solve this without depending on a specific
encryption mode, that would mean doing a cryptographic hash like SHA-256
which would be much less efficient.  This way is sufficient for now, and
it's still compatible with encryption modes like HEH which are strong
pseudorandom permutations.  Also, changing the presented names is still
allowed at any time because they are only provided to allow applications
to do things like delete encrypted directories.  They're not designed to
be used to persistently identify files --- which would be hard to do
anyway, given that they're encrypted after all.

For ease of backports, this patch only makes the minimal fix to both
ext4 and f2fs.  It leaves ubifs as-is, since ubifs doesn't compare the
ciphertext block yet.  Follow-on patches will clean things up properly
and make the filesystems use a shared helper function.

Fixes: 5de0b4d0cd15 ("ext4 crypto: simplify and speed up filename encryption")
Reported-by: Gwendal Grignou &lt;gwendal@chromium.org&gt;
Signed-off-by: Eric Biggers &lt;ebiggers@google.com&gt;
Signed-off-by: Theodore Ts'o &lt;tytso@mit.edu&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;

</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
commit 6b06cdee81d68a8a829ad8e8d0f31d6836744af9 upstream.

When accessing an encrypted directory without the key, userspace must
operate on filenames derived from the ciphertext names, which contain
arbitrary bytes.  Since we must support filenames as long as NAME_MAX,
we can't always just base64-encode the ciphertext, since that may make
it too long.  Currently, this is solved by presenting long names in an
abbreviated form containing any needed filesystem-specific hashes (e.g.
to identify a directory block), then the last 16 bytes of ciphertext.
This needs to be sufficient to identify the actual name on lookup.

However, there is a bug.  It seems to have been assumed that due to the
use of a CBC (ciphertext block chaining)-based encryption mode, the last
16 bytes (i.e. the AES block size) of ciphertext would depend on the
full plaintext, preventing collisions.  However, we actually use CBC
with ciphertext stealing (CTS), which handles the last two blocks
specially, causing them to appear "flipped".  Thus, it's actually the
second-to-last block which depends on the full plaintext.

This caused long filenames that differ only near the end of their
plaintexts to, when observed without the key, point to the wrong inode
and be undeletable.  For example, with ext4:

    # echo pass | e4crypt add_key -p 16 edir/
    # seq -f "edir/abcdefghijklmnopqrstuvwxyz012345%.0f" 100000 | xargs touch
    # find edir/ -type f | xargs stat -c %i | sort | uniq | wc -l
    100000
    # sync
    # echo 3 &gt; /proc/sys/vm/drop_caches
    # keyctl new_session
    # find edir/ -type f | xargs stat -c %i | sort | uniq | wc -l
    2004
    # rm -rf edir/
    rm: cannot remove 'edir/_A7nNFi3rhkEQlJ6P,hdzluhODKOeWx5V': Structure needs cleaning
    ...

To fix this, when presenting long encrypted filenames, encode the
second-to-last block of ciphertext rather than the last 16 bytes.

Although it would be nice to solve this without depending on a specific
encryption mode, that would mean doing a cryptographic hash like SHA-256
which would be much less efficient.  This way is sufficient for now, and
it's still compatible with encryption modes like HEH which are strong
pseudorandom permutations.  Also, changing the presented names is still
allowed at any time because they are only provided to allow applications
to do things like delete encrypted directories.  They're not designed to
be used to persistently identify files --- which would be hard to do
anyway, given that they're encrypted after all.

For ease of backports, this patch only makes the minimal fix to both
ext4 and f2fs.  It leaves ubifs as-is, since ubifs doesn't compare the
ciphertext block yet.  Follow-on patches will clean things up properly
and make the filesystems use a shared helper function.

Fixes: 5de0b4d0cd15 ("ext4 crypto: simplify and speed up filename encryption")
Reported-by: Gwendal Grignou &lt;gwendal@chromium.org&gt;
Signed-off-by: Eric Biggers &lt;ebiggers@google.com&gt;
Signed-off-by: Theodore Ts'o &lt;tytso@mit.edu&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;

</pre>
</div>
</content>
</entry>
</feed>
