linux.git/fs/xfs, branch v4.19

xfs: fix data corruption w/ unaligned reflink ranges

2018-10-06T01:44:39+00:00

When reflinking sub-file ranges, a data corruption can occur when
the source file range includes a partial EOF block. This shares the
unknown data beyond EOF into the second file at a position inside
EOF, exposing stale data in the second file.

XFS only supports whole block sharing, but we still need to
support whole file reflink correctly.  Hence if the reflink
request includes the last block of the souce file, only proceed with
the reflink operation if it lands at or past the destination file's
current EOF. If it lands within the destination file EOF, reject the
entire request with -EINVAL and make the caller go the hard way.

This avoids the data corruption vector, but also avoids disruption
of returning EINVAL to userspace for the common case of whole file
cloning.

Signed-off-by: Dave Chinner 
Reviewed-by: Darrick J. Wong 
Signed-off-by: Dave Chinner

xfs: fix data corruption w/ unaligned dedupe ranges

2018-10-06T01:44:19+00:00

A deduplication data corruption is Exposed by fstests generic/505 on
XFS. It is caused by extending the block match range to include the
partial EOF block, but then allowing unknown data beyond EOF to be
considered a "match" to data in the destination file because the
comparison is only made to the end of the source file. This corrupts
the destination file when the source extent is shared with it.

XFS only supports whole block dedupe, but we still need to appear to
support whole file dedupe correctly.  Hence if the dedupe request
includes the last block of the souce file, don't include it in the
actual XFS dedupe operation. If the rest of the range dedupes
successfully, then report the partial last block as deduped, too, so
that userspace sees it as a successful dedupe rather than return
EINVAL because we can't dedupe unaligned blocks.

Signed-off-by: Dave Chinner 
Reviewed-by: Darrick J. Wong 
Signed-off-by: Dave Chinner

xfs: update ctime and remove suid before cloning files

2018-10-05T09:05:41+00:00

Before cloning into a file, update the ctime and remove sensitive
attributes like suid, just like we'd do for a regular file write.

Signed-off-by: Darrick J. Wong 
Reviewed-by: Dave Chinner 
Signed-off-by: Dave Chinner

xfs: zero posteof blocks when cloning above eof

2018-10-05T09:04:27+00:00

When we're reflinking between two files and the destination file range
is well beyond the destination file's EOF marker, zero any posteof
speculative preallocations in the destination file so that we don't
expose stale disk contents.  The previous strategy of trying to clear
the preallocations does not work if the destination file has the
PREALLOC flag set.

Uncovered by shared/010.

Reported-by: Zorro Lang 
Bugzilla-id: https://bugzilla.kernel.org/show_bug.cgi?id=201259
Signed-off-by: Darrick J. Wong 
Reviewed-by: Dave Chinner 
Signed-off-by: Dave Chinner

xfs: refactor clonerange preparation into a separate helper

2018-10-05T09:04:22+00:00

Refactor all the reflink preparation steps into a separate helper
that we'll use to land all the upcoming fixes for insufficient input
checks.

This rework also moves the invalidation of the destination range to
the prep function so that it is done before the range is remapped.
This ensures that nobody can access the data in range being remapped
until the remap is complete.

[dgc: fix xfs_reflink_remap_prep() return value and caller check to
handle vfs_clone_file_prep_inodes() returning 0 to mean "nothing to
do". ]

[dgc: make sure length changed by vfs_clone_file_prep_inodes() gets
propagated back to XFS code that does the remapping. ]

Signed-off-by: Darrick J. Wong 
Reviewed-by: Dave Chinner 
Signed-off-by: Dave Chinner

xfs: fix error handling in xfs_bmap_extents_to_btree

2018-09-30T22:11:07+00:00

Commit 01239d77b9dd ("xfs: fix a null pointer dereference in
xfs_bmap_extents_to_btree") attempted to fix a null pointer
dreference when a fuzzing corruption of some kind was found.
This fix was flawed, resulting in assert failures like:

XFS: Assertion failed: ifp->if_broot == NULL, file: fs/xfs/libxfs/xfs_bmap.c, line: 715
.....
Call Trace:
  xfs_bmap_extents_to_btree+0x6b9/0x7b0
  __xfs_bunmapi+0xae7/0xf00
  ? xfs_log_reserve+0x1c8/0x290
  xfs_reflink_remap_extent+0x20b/0x620
  xfs_reflink_remap_blocks+0x7e/0x290
  xfs_reflink_remap_range+0x311/0x530
  vfs_dedupe_file_range_one+0xd7/0xe0
  vfs_dedupe_file_range+0x15b/0x1a0
  do_vfs_ioctl+0x267/0x6c0

The problem is that the error handling code now asserts that the
inode fork is not in btree format before the error handling code
undoes the modifications that put the fork back in extent format.
Fix this by moving the assert back to after the xfs_iroot_realloc()
call that returns the fork to extent format, and clean up the jump
labels to be meaningful.

Also, returning ENOSPC when xfs_btree_get_bufl() fails to
instantiate the buffer that was allocated (the actual fix in the
commit mentioned above) is incorrect. This is a fatal error - only
an invalid block address or a filesystem shutdown can result in
failing to get a buffer here.

Hence change this to EFSCORRUPTED so that the higher layer knows
this was a corruption related failure and should not treat it as an
ENOSPC error.  This should result in a shutdown (via cancelling a
dirty transaction) which is necessary as we do not attempt to clean
up the (invalid) block that we have already allocated.

Signed-off-by: Dave Chinner 
Reviewed-by: Darrick J. Wong 
Signed-off-by: Dave Chinner

xfs: remove invalid log recovery first/last cycle check

2018-09-29T03:50:41+00:00

One of the first steps of log recovery is to check for the special
case of a zeroed log. If the first cycle in the log is zero or the
tail portion of the log is zeroed, the head is set to the first
instance of cycle 0. xlog_find_zeroed() includes a sanity check that
enforces that the first cycle in the log must be 1 if the last cycle
is 0. While this is true in most cases, the check is not totally
valid because it doesn't consider the case where the filesystem
crashed after a partial/out of order log buffer completion that
wraps around the end of the physical log.

For example, consider a filesystem that has completed most of the
first cycle of the log, reaches the end of the physical log and
splits the next single log buffer write into two in order to wrap
around the end of the log. If these I/Os are reordered, the second
(wrapped) I/O completes and the first happens to fail, the log is
left in a state where the last cycle of the log is 0 and the first
cycle is 2. This causes the xlog_find_zeroed() sanity check to fail
and prevents the filesystem from mounting. This situation has been
reproduced on particular systems via repeated runs of generic/475.

This is an expected state that log recovery already knows how to
deal with, however. Since the log is still partially zeroed, the
head is detected correctly and points to a valid tail. The
subsequent stale block detection clears blocks beyond the head up to
the tail (within a maximum range), with the express purpose of
clearing such out of order writes. As expected, this removes the out
of order cycle 2 blocks at the physical start of the log.

In other words, the only thing that prevents a clean mount and
recovery of the filesystem in this scenario is the specific (last ==
0 && first != 1) sanity check in xlog_find_zeroed(). Since the log
head/tail are now independently validated via cycle, log record and
CRC checks, this highly specific first cycle check is of dubious
value. Remove it and rely on the higher level validation to
determine whether log content is sane and recoverable.

Signed-off-by: Brian Foster 
Reviewed-by: Dave Chinner 
Signed-off-by: Dave Chinner

xfs: validate inode di_forkoff

2018-09-29T03:50:13+00:00

Verify the inode di_forkoff, lifted from xfs_repair's
process_check_inode_forkoff().

Signed-off-by: Eric Sandeen 
Reviewed-by: Brian Foster 
Signed-off-by: Dave Chinner

xfs: skip delalloc COW blocks in xfs_reflink_end_cow

2018-09-29T03:49:58+00:00

The iomap direct I/O code issues a single ->end_io call for the whole
I/O request, and if some of the extents cowered needed a COW operation
it will call xfs_reflink_end_cow over the whole range.

When we do AIO writes we drop the iolock after doing the initial setup,
but before the I/O completion.  Between dropping the lock and completing
the I/O we can have a racing buffered write create new delalloc COW fork
extents in the region covered by the outstanding direct I/O write, and
thus see delalloc COW fork extents in xfs_reflink_end_cow.  As
concurrent writes are fundamentally racy and no guarantees are given we
can simply skip those.

This can be easily reproduced with xfstests generic/208 in always_cow
mode.

Signed-off-by: Christoph Hellwig 
Reviewed-by: Darrick J. Wong 
Signed-off-by: Dave Chinner

xfs: don't treat unknown di_flags2 as corruption in scrub

2018-09-29T03:49:00+00:00

xchk_inode_flags2() currently treats any di_flags2 values that the
running kernel doesn't recognize as corruption, and calls
xchk_ino_set_corrupt() if they are set.  However, it's entirely possible
that these flags were set in some newer kernel and are quite valid,
but ignored in this kernel.

(Validators don't care one bit about unknown di_flags2.)

Call xchk_ino_set_warning instead, because this may or may not actually
indicate a problem.

Signed-off-by: Eric Sandeen 
Reviewed-by: Darrick J. Wong 
Signed-off-by: Dave Chinner