| Commit message (Collapse) | Author | Age | Files | Lines |
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When CONFIG_DM_VERITY=y, dm_is_verity_target() returned true for any
builtin dm target, not just dm-verity. Fix this by checking for
verity_target instead of THIS_MODULE (which is NULL for builtin code).
Fixes: b6c1c5745ccc ("dm: Add verity helpers for LoadPin")
Cc: stable@vger.kernel.org
Cc: Matthias Kaehlcke <mka@chromium.org>
Cc: Kees Cook <keescook@chromium.org>
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
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Remove use of the blk_limits_io_{min,opt} and assign the values directly
to the queue_limits structure. For the io_opt this is a completely
mechanical change, for io_min it removes flooring the limit to the
physical and logical block size in the particular caller. But as
blk_validate_limits will do the same later when actually applying the
limits, there still is no change in overall behavior.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
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Currently dm-verity computes the hash of each block by using multiple
calls to the "ahash" crypto API. While the exact sequence depends on
the chosen dm-verity settings, in the vast majority of cases it is:
1. crypto_ahash_init()
2. crypto_ahash_update() [salt]
3. crypto_ahash_update() [data]
4. crypto_ahash_final()
This is inefficient for two main reasons:
- It makes multiple indirect calls, which is expensive on modern CPUs
especially when mitigations for CPU vulnerabilities are enabled.
Since the salt is the same across all blocks on a given dm-verity
device, a much more efficient sequence would be to do an import of the
pre-salted state, then a finup.
- It uses the ahash (asynchronous hash) API, despite the fact that
CPU-based hashing is almost always used in practice, and therefore it
experiences the overhead of the ahash-based wrapper for shash.
Because dm-verity was intentionally converted to ahash to support
off-CPU crypto accelerators, a full reversion to shash might not be
acceptable. Yet, we should still provide a fast path for shash with
the most common dm-verity settings.
Another reason for shash over ahash is that the upcoming multibuffer
hashing support, which is specific to CPU-based hashing, is much
better suited for shash than for ahash. Supporting it via ahash would
add significant complexity and overhead. And it's not possible for
the "same" code to properly support both multibuffer hashing and HW
accelerators at the same time anyway, given the different computation
models. Unfortunately there will always be code specific to each
model needed (for users who want to support both).
Therefore, this patch adds a new shash import+finup based fast path to
dm-verity. It is used automatically when appropriate. This makes
dm-verity optimized for what the vast majority of users want: CPU-based
hashing with the most common settings, while still retaining support for
rarer settings and off-CPU crypto accelerators.
In benchmarks with veritysetup's default parameters (SHA-256, 4K data
and hash block sizes, 32-byte salt), which also match the parameters
that Android currently uses, this patch improves block hashing
performance by about 15% on x86_64 using the SHA-NI instructions, or by
about 5% on arm64 using the ARMv8 SHA2 instructions. On x86_64 roughly
two-thirds of the improvement comes from the use of import and finup,
while the remaining third comes from the switch from ahash to shash.
Note that another benefit of using "import" to handle the salt is that
if the salt size is equal to the input size of the hash algorithm's
compression function, e.g. 64 bytes for SHA-256, then the performance is
exactly the same as no salt. This doesn't seem to be much better than
veritysetup's current default of 32-byte salts, due to the way SHA-256's
finalization padding works, but it should be marginally better.
Reviewed-by: Sami Tolvanen <samitolvanen@google.com>
Acked-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
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In preparation for adding shash support to dm-verity, change
verity_hash() to take a pointer to a struct dm_verity_io instead of a
pointer to the ahash_request embedded inside it.
Reviewed-by: Sami Tolvanen <samitolvanen@google.com>
Acked-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
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dm-verity needs to access data blocks by virtual address in three
different cases (zeroization, recheck, and forward error correction),
and one more case (shash support) is coming. Since it's guaranteed that
dm-verity data blocks never cross pages, and kmap_local_page and
kunmap_local are no-ops on modern platforms anyway, just unconditionally
"map" every data block's page and work with the virtual buffer directly.
This simplifies the code and eliminates unnecessary overhead.
Reviewed-by: Sami Tolvanen <samitolvanen@google.com>
Acked-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
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Since Linux v6.1, some filesystems support submitting direct I/O that is
aligned to only dma_alignment instead of the logical_block_size
alignment that was required before. I/O that is not aligned to the
logical_block_size is difficult to handle in device-mapper targets that
do cryptographic processing of data, as it makes the units of data that
are hashed or encrypted possibly be split across pages, creating rarely
used and rarely tested edge cases.
As such, dm-crypt and dm-integrity have already opted out of this by
setting dma_alignment to 'logical_block_size - 1'.
Although dm-verity does have code that handles these cases (or at least
is intended to do so), supporting direct I/O with such a low amount of
alignment is not really useful on dm-verity devices. So, opt dm-verity
out of it too so that it's not necessary to handle these edge cases.
Reviewed-by: Sami Tolvanen <samitolvanen@google.com>
Acked-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
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Change the digest fields in struct dm_verity_io from variable-length to
fixed-length, since their maximum length is fixed at
HASH_MAX_DIGESTSIZE, i.e. 64 bytes, which is not too big. This is
simpler and makes the fields a bit faster to access.
(HASH_MAX_DIGESTSIZE did not exist when this code was written, which may
explain why it wasn't used.)
This makes the verity_io_real_digest() and verity_io_want_digest()
functions trivial, but this patch leaves them in place temporarily since
most of their callers will go away in a later patch anyway.
Reviewed-by: Sami Tolvanen <samitolvanen@google.com>
Acked-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
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Move the code that handles mismatches of data block hashes into its own
function so that it doesn't clutter up verity_verify_io().
Reviewed-by: Sami Tolvanen <samitolvanen@google.com>
Acked-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
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Move the code that sets up the hash transformation into its own
function. No change in behavior.
Reviewed-by: Sami Tolvanen <samitolvanen@google.com>
Acked-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
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git://git.kernel.org/pub/scm/linux/kernel/git/device-mapper/linux-dm
Pull device mapper BH workqueue conversion from Mike Snitzer:
"Convert the DM verity and crypt targets from (ab)using tasklets to
using BH workqueues.
These changes were coordinated with Tejun and are based ontop of DM's
6.9 changes and Tejun's 6.9 workqueue tree"
* tag 'for-6.9/dm-bh-wq' of git://git.kernel.org/pub/scm/linux/kernel/git/device-mapper/linux-dm:
dm-verity: Convert from tasklet to BH workqueue
dm-crypt: Convert from tasklet to BH workqueue
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The only generic interface to execute asynchronously in the BH context is
tasklet; however, it's marked deprecated and has some design flaws. To
replace tasklets, BH workqueue support was recently added. A BH workqueue
behaves similarly to regular workqueues except that the queued work items
are executed in the BH context.
This commit converts dm-verity from tasklet to BH workqueue. It
backfills tasklet code that was removed with commit 0a9bab391e33
("dm-crypt, dm-verity: disable tasklets") and tweaks to use BH
workqueue (and does some renaming).
This is a minimal conversion which doesn't rename the related names
including the "try_verify_in_tasklet" option. If this patch is applied, a
follow-up patch would be necessary. I couldn't decide whether the option
name would need to be updated too.
Signed-off-by: Tejun Heo <tj@kernel.org>
[snitzer: rename 'use_tasklet' to 'use_bh_wq' and 'in_tasklet' to 'in_bh']
Signed-off-by: Mike Snitzer <snitzer@kernel.org>
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git://git.kernel.org/pub/scm/linux/kernel/git/device-mapper/linux-dm
Pull device mapper updates from Mike Snitzer:
- Fix DM core's IO submission (which include dm-io and dm-bufio) such
that a bio's IO priority is propagated. Work focused on enabling both
DM crypt and verity targets to retain the appropriate IO priority
- Fix DM raid reshape logic to not allow an empty flush bio to be
requeued due to false concern about the bio, which doesn't have a
data payload, accessing beyond the end of the device
- Fix DM core's internal resume so that it properly calls both presume
and resume methods, which fixes the potential for a postsuspend and
resume imbalance
- Update DM verity target to set DM_TARGET_SINGLETON flag because it
doesn't make sense to have a DM table with a mix of targets that
include dm-verity
- Small cleanups in DM crypt, thin, and integrity targets
- Fix references to dm-devel mailing list to use latest list address
* tag 'for-6.9/dm-changes' of git://git.kernel.org/pub/scm/linux/kernel/git/device-mapper/linux-dm:
dm: call the resume method on internal suspend
dm raid: fix false positive for requeue needed during reshape
dm-integrity: set max_integrity_segments in dm_integrity_io_hints
dm: update relevant MODULE_AUTHOR entries to latest dm-devel mailing list
dm ioctl: update DM_DRIVER_EMAIL to new dm-devel mailing list
dm verity: set DM_TARGET_SINGLETON feature flag
dm crypt: Fix IO priority lost when queuing write bios
dm verity: Fix IO priority lost when reading FEC and hash
dm bufio: Support IO priority
dm io: Support IO priority
dm crypt: remove redundant state settings after waking up
dm thin: add braces around conditional code that spans lines
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The device-mapper has a flag to mark targets as singleton, which is a
required flag for immutable targets. Without this flag, multiple
dm-verity targets can be added to a mapped device, which has no
practical use cases and will let dm_table_get_immutable_target return
NULL. This patch adds the missing flag, restricting only one
dm-verity target per mapped device.
Signed-off-by: Fan Wu <wufan@linux.microsoft.com>
Signed-off-by: Mike Snitzer <snitzer@kernel.org>
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After obtaining the data, verification or error correction process may
trigger a new IO that loses the priority of the original IO, that is,
the verification of the higher priority IO may be blocked by the lower
priority IO.
Make the IO used for verification and error correction follow the
priority of the original IO.
Co-developed-by: Yibin Ding <yibin.ding@unisoc.com>
Signed-off-by: Yibin Ding <yibin.ding@unisoc.com>
Signed-off-by: Hongyu Jin <hongyu.jin@unisoc.com>
Reviewed-by: Eric Biggers <ebiggers@google.com>
Reviewed-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@kernel.org>
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Some IO will dispatch from kworker with different io_context settings
than the submitting task, we may need to specify a priority to avoid
losing priority.
Add IO priority parameter to dm_io() and update all callers.
Co-developed-by: Yibin Ding <yibin.ding@unisoc.com>
Signed-off-by: Yibin Ding <yibin.ding@unisoc.com>
Signed-off-by: Hongyu Jin <hongyu.jin@unisoc.com>
Reviewed-by: Eric Biggers <ebiggers@google.com>
Reviewed-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@kernel.org>
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The newly added integrity_recheck() function has another larger stack
allocation, just like its caller integrity_metadata(). When it gets
inlined, the combination of the two exceeds the warning limit for 32-bit
architectures and possibly risks an overflow when this is called from
a deep call chain through a file system:
drivers/md/dm-integrity.c:1767:13: error: stack frame size (1048) exceeds limit (1024) in 'integrity_metadata' [-Werror,-Wframe-larger-than]
1767 | static void integrity_metadata(struct work_struct *w)
Since the caller at this point is done using its checksum buffer,
just reuse the same buffer in the new function to avoid the double
allocation.
[Mikulas: add "noinline" to integrity_recheck and verity_recheck.
These functions are only called on error, so they shouldn't bloat the
stack frame or code size of the caller.]
Fixes: c88f5e553fe3 ("dm-integrity: recheck the integrity tag after a failure")
Fixes: 9177f3c0dea6 ("dm-verity: recheck the hash after a failure")
Cc: stable@vger.kernel.org
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@kernel.org>
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Signed-off-by: Mike Snitzer <snitzer@kernel.org>
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If a userspace process reads (with O_DIRECT) multiple blocks into the same
buffer, dm-verity reports an error [1].
This commit fixes dm-verity, so that if hash verification fails, the data
is read again into a kernel buffer (where userspace can't modify it) and
the hash is rechecked. If the recheck succeeds, the content of the kernel
buffer is copied into the user buffer; if the recheck fails, an error is
reported.
[1] https://people.redhat.com/~mpatocka/testcases/blk-auth-modify/read2.c
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Cc: stable@vger.kernel.org
Signed-off-by: Mike Snitzer <snitzer@kernel.org>
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Tasklets have an inherent problem with memory corruption. The function
tasklet_action_common calls tasklet_trylock, then it calls the tasklet
callback and then it calls tasklet_unlock. If the tasklet callback frees
the structure that contains the tasklet or if it calls some code that may
free it, tasklet_unlock will write into free memory.
The commits 8e14f610159d and d9a02e016aaf try to fix it for dm-crypt, but
it is not a sufficient fix and the data corruption can still happen [1].
There is no fix for dm-verity and dm-verity will write into free memory
with every tasklet-processed bio.
There will be atomic workqueues implemented in the kernel 6.9 [2]. They
will have better interface and they will not suffer from the memory
corruption problem.
But we need something that stops the memory corruption now and that can be
backported to the stable kernels. So, I'm proposing this commit that
disables tasklets in both dm-crypt and dm-verity. This commit doesn't
remove the tasklet support, because the tasklet code will be reused when
atomic workqueues will be implemented.
[1] https://lore.kernel.org/all/d390d7ee-f142-44d3-822a-87949e14608b@suse.de/T/
[2] https://lore.kernel.org/lkml/20240130091300.2968534-1-tj@kernel.org/
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Cc: stable@vger.kernel.org
Fixes: 39d42fa96ba1b ("dm crypt: add flags to optionally bypass kcryptd workqueues")
Fixes: 5721d4e5a9cdb ("dm verity: Add optional "try_verify_in_tasklet" feature")
Signed-off-by: Mike Snitzer <snitzer@kernel.org>
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We found an issue under Android OTA scenario that many BIOs have to do
FEC where the data under dm-verity is 100% complete and no corruption.
Android OTA has many dm-block layers, from upper to lower:
dm-verity
dm-snapshot
dm-origin & dm-cow
dm-linear
ufs
DM tables have to change 2 times during Android OTA merging process.
When doing table change, the dm-snapshot will be suspended for a while.
During this interval, many readahead IOs are submitted to dm_verity
from filesystem. Then the kverity works are busy doing FEC process
which cost too much time to finish dm-verity IO. This causes needless
delay which feels like system is hung.
After adding debugging it was found that each readahead IO needed
around 10s to finish when this situation occurred. This is due to IO
amplification:
dm-snapshot suspend
erofs_readahead // 300+ io is submitted
dm_submit_bio (dm_verity)
dm_submit_bio (dm_snapshot)
bio return EIO
bio got nothing, it's empty
verity_end_io
verity_verify_io
forloop range(0, io->n_blocks) // each io->nblocks ~= 20
verity_fec_decode
fec_decode_rsb
fec_read_bufs
forloop range(0, v->fec->rsn) // v->fec->rsn = 253
new_read
submit_bio (dm_snapshot)
end loop
end loop
dm-snapshot resume
Readahead BIOs get nothing while dm-snapshot is suspended, so all of
them will cause verity's FEC.
Each readahead BIO needs to verify ~20 (io->nblocks) blocks.
Each block needs to do FEC, and every block needs to do 253
(v->fec->rsn) reads.
So during the suspend interval(~200ms), 300 readahead BIOs trigger
~1518000 (300*20*253) IOs to dm-snapshot.
As readahead IO is not required by userspace, and to fix this issue,
it is best to pass readahead errors to upper layer to handle it.
Cc: stable@vger.kernel.org
Fixes: a739ff3f543a ("dm verity: add support for forward error correction")
Signed-off-by: Wu Bo <bo.wu@vivo.com>
Reviewed-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@kernel.org>
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If BIO error, verity_end_io() can call verity_finish_io() before
verity_fec_init_io(). Therefore, fec_io->rs is not initialized and
may crash when doing memory freeing in verity_fec_finish_io().
Crash call stack:
die+0x90/0x2b8
__do_kernel_fault+0x260/0x298
do_bad_area+0x2c/0xdc
do_translation_fault+0x3c/0x54
do_mem_abort+0x54/0x118
el1_abort+0x38/0x5c
el1h_64_sync_handler+0x50/0x90
el1h_64_sync+0x64/0x6c
free_rs+0x18/0xac
fec_rs_free+0x10/0x24
mempool_free+0x58/0x148
verity_fec_finish_io+0x4c/0xb0
verity_end_io+0xb8/0x150
Cc: stable@vger.kernel.org # v6.0+
Fixes: 5721d4e5a9cd ("dm verity: Add optional "try_verify_in_tasklet" feature")
Signed-off-by: Wu Bo <bo.wu@vivo.com>
Reviewed-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@kernel.org>
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The commit 5721d4e5a9cd enhanced dm-verity, so that it can verify blocks
from tasklets rather than from workqueues. This reportedly improves
performance significantly.
However, dm-verity was using the flag CRYPTO_TFM_REQ_MAY_SLEEP from
tasklets which resulted in warnings about sleeping function being called
from non-sleeping context.
BUG: sleeping function called from invalid context at crypto/internal.h:206
in_atomic(): 1, irqs_disabled(): 0, non_block: 0, pid: 14, name: ksoftirqd/0
preempt_count: 100, expected: 0
RCU nest depth: 0, expected: 0
CPU: 0 PID: 14 Comm: ksoftirqd/0 Tainted: G W 6.7.0-rc1 #1
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.14.0-2 04/01/2014
Call Trace:
<TASK>
dump_stack_lvl+0x32/0x50
__might_resched+0x110/0x160
crypto_hash_walk_done+0x54/0xb0
shash_ahash_update+0x51/0x60
verity_hash_update.isra.0+0x4a/0x130 [dm_verity]
verity_verify_io+0x165/0x550 [dm_verity]
? free_unref_page+0xdf/0x170
? psi_group_change+0x113/0x390
verity_tasklet+0xd/0x70 [dm_verity]
tasklet_action_common.isra.0+0xb3/0xc0
__do_softirq+0xaf/0x1ec
? smpboot_thread_fn+0x1d/0x200
? sort_range+0x20/0x20
run_ksoftirqd+0x15/0x30
smpboot_thread_fn+0xed/0x200
kthread+0xdc/0x110
? kthread_complete_and_exit+0x20/0x20
ret_from_fork+0x28/0x40
? kthread_complete_and_exit+0x20/0x20
ret_from_fork_asm+0x11/0x20
</TASK>
This commit fixes dm-verity so that it doesn't use the flags
CRYPTO_TFM_REQ_MAY_SLEEP and CRYPTO_TFM_REQ_MAY_BACKLOG from tasklets. The
crypto API would do GFP_ATOMIC allocation instead, it could return -ENOMEM
and we catch -ENOMEM in verity_tasklet and requeue the request to the
workqueue.
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Cc: stable@vger.kernel.org # v6.0+
Fixes: 5721d4e5a9cd ("dm verity: Add optional "try_verify_in_tasklet" feature")
Signed-off-by: Mike Snitzer <snitzer@kernel.org>
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The only overlap between the block open flags mapped into the fmode_t and
other uses of fmode_t are FMODE_READ and FMODE_WRITE. Define a new
blk_mode_t instead for use in blkdev_get_by_{dev,path}, ->open and
->ioctl and stop abusing fmode_t.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: Jack Wang <jinpu.wang@ionos.com> [rnbd]
Reviewed-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: Christian Brauner <brauner@kernel.org>
Link: https://lore.kernel.org/r/20230608110258.189493-28-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Eliminate duplicate boilerplate code for simple modules that contain
a single DM target driver without any additional setup code.
Add a new module_dm() macro, which replaces the module_init() and
module_exit() with template functions that call dm_register_target()
and dm_unregister_target() respectively.
Signed-off-by: Yangtao Li <frank.li@vivo.com>
Signed-off-by: Mike Snitzer <snitzer@kernel.org>
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Simplifies each DM target's init method by making dm_register_target()
responsible for its error reporting (on behalf of targets).
Signed-off-by: Yangtao Li <frank.li@vivo.com>
Signed-off-by: Mike Snitzer <snitzer@kernel.org>
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dm-verity signals integrity violations by returning I/O errors
to user space. To identify integrity violations by a controlling
instance, the kernel audit subsystem can be used to emit audit
events to user space. Analogous to dm-integrity, we also use the
dm-audit submodule allowing to emit audit events on verification
failures of metadata and data blocks as well as if max corrupted
errors are reached.
The construction and destruction of verity device mappings are
also relevant for auditing a system. Thus, those events are also
logged as audit events.
Tested by starting a container with the container manager (cmld) of
GyroidOS which uses a dm-verity protected rootfs image root.img mapped
to /dev/mapper/<uuid>-root. One block was manipulated in the
underlying image file and repeated reads of the verity device were
performed again until the max corrupted errors is reached, e.g.:
dd if=/dev/urandom of=root.img bs=512 count=1 seek=1000
for i in range {1..101}; do \
dd if=/dev/mapper/<uuid>-root of=/dev/null bs=4096 \
count=1 skip=1000 \
done
The resulting audit log looks as follows:
type=DM_CTRL msg=audit(1677618791.876:962):
module=verity op=ctr ppid=4876 pid=29102 auid=0 uid=0 gid=0
euid=0 suid=0 fsuid=0 egid=0 sgid=0 fsgid=0 tty=(none) ses=44
comm="cmld" exe="/usr/sbin/cml/cmld" subj=unconfined
dev=254:3 error_msg='success' res=1
type=DM_EVENT msg=audit(1677619463.786:1074): module=verity
op=verify-data dev=7:0 sector=1000 res=0
...
type=DM_EVENT msg=audit(1677619596.727:1162): module=verity
op=verify-data dev=7:0 sector=1000 res=0
type=DM_EVENT msg=audit(1677619596.731:1163): module=verity
op=max-corrupted-errors dev=254:3 sector=? res=0
Signed-off-by: Michael Weiß <michael.weiss@aisec.fraunhofer.de>
Acked-by: Paul Moore <paul@paul-moore.com>
Signed-off-by: Mike Snitzer <snitzer@kernel.org>
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In verity_end_io(), if bi_status is not BLK_STS_OK, it can be return
directly. But if FEC configured, it is desired to correct the data page
through verity_verify_io. And the return value will be converted to
blk_status and passed to verity_finish_io().
BTW, when a bit is set in v->validated_blocks, verity_verify_io() skips
verification regardless of I/O error for the corresponding bio. In this
case, the I/O error could not be returned properly, and as a result,
there is a problem that abnormal data could be read for the
corresponding block.
To fix this problem, when an I/O error occurs, do not skip verification
even if the bit related is set in v->validated_blocks.
Fixes: 843f38d382b1 ("dm verity: add 'check_at_most_once' option to only validate hashes once")
Cc: stable@vger.kernel.org
Reviewed-by: Sungjong Seo <sj1557.seo@samsung.com>
Signed-off-by: Yeongjin Gil <youngjin.gil@samsung.com>
Signed-off-by: Mike Snitzer <snitzer@kernel.org>
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Signed-off-by: Heinz Mauelshagen <heinzm@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@kernel.org>
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Signed-off-by: Heinz Mauelshagen <heinzm@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@kernel.org>
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Signed-off-by: Heinz Mauelshagen <heinzm@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@kernel.org>
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Signed-off-by: Heinz Mauelshagen <heinzm@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@kernel.org>
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Signed-off-by: Heinz Mauelshagen <heinzm@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@kernel.org>
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Signed-off-by: Heinz Mauelshagen <heinzm@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@kernel.org>
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Setting WQ_UNBOUND increases scheduler latency on ARM64. This is
likely due to the asymmetric architecture of ARM64 processors.
I've been unable to reproduce the results that claim WQ_UNBOUND gives
a performance boost on x86-64.
This flag is causing performance issues for multiple subsystems within
Android. Notably, the same slowdown exists for decompression with
EROFS.
| open-prebuilt-camera | WQ_UNBOUND | ~WQ_UNBOUND |
|-----------------------|------------|---------------|
| verity wait time (us) | 11746 | 119 (-98%) |
| erofs wait time (us) | 357805 | 174205 (-51%) |
| sha256 ramdisk random read | WQ_UNBOUND | ~WQ_UNBOUND |
|----------------------------|-----------=---|-------------|
| arm64 (accelerated) | bw=42.4MiB/s | bw=212MiB/s |
| arm64 (generic) | bw=16.5MiB/s | bw=48MiB/s |
| x86_64 (generic) | bw=233MiB/s | bw=230MiB/s |
Using a alloc_workqueue() @max_active arg of num_online_cpus() only
made sense with WQ_UNBOUND. Switch the @max_active arg to 0 (aka
default, which is 256 per-cpu).
Also, eliminate 'wq_flags' since it really doesn't serve a purpose.
Cc: Sami Tolvanen <samitolvanen@google.com>
Cc: Eric Biggers <ebiggers@kernel.org>
Signed-off-by: Nathan Huckleberry <nhuck@google.com>
Reviewed-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@kernel.org>
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WQ_HIGHPRI increases throughput and decreases disk latency when using
dm-verity. This is important in Android for camera startup speed.
The following tests were run by doing 60 seconds of random reads using
a dm-verity device backed by two ramdisks.
Without WQ_HIGHPRI
lat (usec): min=13, max=3947, avg=69.53, stdev=50.55
READ: bw=51.1MiB/s (53.6MB/s), 51.1MiB/s-51.1MiB/s (53.6MB/s-53.6MB/s)
With WQ_HIGHPRI:
lat (usec): min=13, max=7854, avg=31.15, stdev=30.42
READ: bw=116MiB/s (121MB/s), 116MiB/s-116MiB/s (121MB/s-121MB/s)
Further testing was done by measuring how long it takes to open a
camera on an Android device.
Without WQ_HIGHPRI
Total verity work queue wait times (ms):
880.960, 789.517, 898.852
With WQ_HIGHPRI:
Total verity work queue wait times (ms):
528.824, 439.191, 433.300
The average time to open the camera is reduced by 350ms (or 40-50%).
Signed-off-by: Nathan Huckleberry <nhuck@google.com>
Signed-off-by: Mike Snitzer <snitzer@kernel.org>
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Verity targets can be configured to ignore corrupted data blocks.
LoadPin must only trust verity targets that are configured to
perform some kind of enforcement when data corruption is detected,
like returning an error, restarting the system or triggering a
panic.
Fixes: b6c1c5745ccc ("dm: Add verity helpers for LoadPin")
Reported-by: Sarthak Kukreti <sarthakkukreti@chromium.org>
Signed-off-by: Matthias Kaehlcke <mka@chromium.org>
Reviewed-by: Sarthak Kukreti <sarthakkukreti@chromium.org>
Cc: stable@vger.kernel.org
Signed-off-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20220907133055.1.Ic8a1dafe960dc0f8302e189642bc88ebb785d274@changeid
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git://git.kernel.org/pub/scm/linux/kernel/git/device-mapper/linux-dm
Pull device mapper fixes from Mike Snitzer:
- A few fixes for the DM verity and bufio changes in this merge window
- A smatch warning fix for DM writecache locking in writecache_map
* tag 'for-6.0/dm-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/device-mapper/linux-dm:
dm bufio: fix some cases where the code sleeps with spinlock held
dm writecache: fix smatch warning about invalid return from writecache_map
dm verity: fix verity_parse_opt_args parsing
dm verity: fix DM_VERITY_OPTS_MAX value yet again
dm bufio: simplify DM_BUFIO_CLIENT_NO_SLEEP locking
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Commit df326e7a0699 ("dm verity: allow optional args to alter primary
args handling") introduced a bug where verity_parse_opt_args() wouldn't
properly shift past an optional argument's additional params (by
ignoring them).
Fix this by avoiding returning with error if an unknown argument is
encountered when @only_modifier_opts=true is passed to
verity_parse_opt_args().
In practice this regressed the cryptsetup testsuite's FEC testing
because unknown optional arguments were encountered, wherey
short-circuiting ever testing FEC mode. With this fix all of the
cryptsetup testsuite's verity FEC tests pass.
Fixes: df326e7a0699 ("dm verity: allow optional args to alter primary args handling")
Reported-by: Milan Broz <gmazyland@gmail.com>>
Signed-off-by: Mike Snitzer <snitzer@kernel.org>
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Must account for the possibility that "try_verify_in_tasklet" is used.
This is the same issue that was fixed with commit 160f99db94322 -- it
is far too easy to miss that additional a new argument(s) require
bumping DM_VERITY_OPTS_MAX accordingly.
Fixes: 5721d4e5a9cd ("dm verity: Add optional "try_verify_in_tasklet" feature")
Signed-off-by: Mike Snitzer <snitzer@kernel.org>
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git://git.kernel.org/pub/scm/linux/kernel/git/device-mapper/linux-dm
Pull more device mapper updates from Mike Snitzer:
- Add flags argument to dm_bufio_client_create and introduce
DM_BUFIO_CLIENT_NO_SLEEP flag to have dm-bufio use spinlock rather
than mutex for its locking.
- Add optional "try_verify_in_tasklet" feature to DM verity target.
This feature gives users the option to improve IO latency by using a
tasklet to verify, using hashes in bufio's cache, rather than wait to
schedule a work item via workqueue. But if there is a bufio cache
miss, or an error, then the tasklet will fallback to using workqueue.
- Incremental changes to both dm-bufio and the DM verity target to use
jump_label to minimize cost of branching associated with the niche
"try_verify_in_tasklet" feature. DM-bufio in particular is used by
quite a few other DM targets so it doesn't make sense to incur
additional bufio cost in those targets purely for the benefit of this
niche verity feature if the feature isn't ever used.
- Optimize verity_verify_io, which is used by both workqueue and
tasklet based verification, if FEC is not configured or tasklet based
verification isn't used.
- Remove DM verity target's verify_wq's use of the WQ_CPU_INTENSIVE
flag since it uses WQ_UNBOUND. Also, use the WQ_HIGHPRI flag if
"try_verify_in_tasklet" is specified.
* tag 'for-6.0/dm-changes-2' of git://git.kernel.org/pub/scm/linux/kernel/git/device-mapper/linux-dm:
dm verity: have verify_wq use WQ_HIGHPRI if "try_verify_in_tasklet"
dm verity: remove WQ_CPU_INTENSIVE flag since using WQ_UNBOUND
dm verity: only copy bvec_iter in verity_verify_io if in_tasklet
dm verity: optimize verity_verify_io if FEC not configured
dm verity: conditionally enable branching for "try_verify_in_tasklet"
dm bufio: conditionally enable branching for DM_BUFIO_CLIENT_NO_SLEEP
dm verity: allow optional args to alter primary args handling
dm verity: Add optional "try_verify_in_tasklet" feature
dm bufio: Add DM_BUFIO_CLIENT_NO_SLEEP flag
dm bufio: Add flags argument to dm_bufio_client_create
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Allow verify_wq to preempt softirq since verification in tasklet will
fall-back to using it for error handling (or if the bufio cache
doesn't have required hashes).
Suggested-by: Nathan Huckleberry <nhuck@google.com>
Signed-off-by: Mike Snitzer <snitzer@kernel.org>
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The documentation [1] says that WQ_CPU_INTENSIVE is "meaningless" for
unbound wq. So remove WQ_CPU_INTENSIVE from the verify_wq allocation.
1. https://www.kernel.org/doc/html/latest/core-api/workqueue.html#flags
Suggested-by: Maksym Planeta <mplaneta@os.inf.tu-dresden.de>
Signed-off-by: Mike Snitzer <snitzer@kernel.org>
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Avoid extra bvec_iter copy unless it is needed to allow retrying
verification, that failed from a tasklet, from a workqueue.
Signed-off-by: Mike Snitzer <snitzer@kernel.org>
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Only declare and copy bvec_iter if CONFIG_DM_VERITY_FEC is defined and
FEC enabled for the verity device.
Signed-off-by: Mike Snitzer <snitzer@kernel.org>
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Use jump_label to limit the need for branching unless the optional
"try_verify_in_tasklet" feature is used.
Signed-off-by: Mike Snitzer <snitzer@kernel.org>
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The previous commit ("dm verity: Add optional "try_verify_in_tasklet"
feature") imposed that CRYPTO_ALG_ASYNC mask be used even if the
optional "try_verify_in_tasklet" feature was not specified. This was
because verity_parse_opt_args() was called after handling the primary
args (due to it having data dependencies on having first parsed all
primary args).
Enhance verity_ctr() so that simple optional args, that don't have a
data dependency on primary args parsing, can alter how the primary
args are handled. In practice this means verity_parse_opt_args() gets
called twice. First with the new 'only_modifier_opts' arg set to true,
then again with it set to false _after_ parsing all primary args.
This allows the v->use_tasklet flag to be properly set and then used
when verity_ctr() parses the primary args and then calls
crypto_alloc_ahash() with CRYPTO_ALG_ASYNC conditionally set.
Signed-off-by: Mike Snitzer <snitzer@kernel.org>
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Using tasklets for disk verification can reduce IO latency. When there
are accelerated hash instructions it is often better to compute the
hash immediately using a tasklet rather than deferring verification to
a work-queue. This reduces time spent waiting to schedule work-queue
jobs, but requires spending slightly more time in interrupt context.
If the dm-bufio cache does not have the required hashes we fallback to
the work-queue implementation. FEC is only possible using work-queue
because code to support the FEC feature may sleep.
The following shows a speed comparison of random reads on a dm-verity
device. The dm-verity device uses a 1G ramdisk for data and a 1G
ramdisk for hashes. One test was run using tasklets and one test was
run using the existing work-queue solution. Both tests were run when
the dm-bufio cache was hot. The tasklet implementation performs
significantly better since there is no time spent waiting for
work-queue jobs to be scheduled.
READ: bw=181MiB/s (190MB/s), 181MiB/s-181MiB/s (190MB/s-190MB/s),
io=512MiB (537MB), run=2827-2827msec
READ: bw=23.6MiB/s (24.8MB/s), 23.6MiB/s-23.6MiB/s (24.8MB/s-24.8MB/s),
io=512MiB (537MB), run=21688-21688msec
Signed-off-by: Nathan Huckleberry <nhuck@google.com>
Signed-off-by: Mike Snitzer <snitzer@kernel.org>
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Add a flags argument to dm_bufio_client_create and update all the
callers. This is in preparation to add the DM_BUFIO_NO_SLEEP flag.
Signed-off-by: Nathan Huckleberry <nhuck@google.com>
Signed-off-by: Mike Snitzer <snitzer@kernel.org>
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git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux
Pull hardening updates from Kees Cook:
- Fix Sparse warnings with randomizd kstack (GONG, Ruiqi)
- Replace uintptr_t with unsigned long in usercopy (Jason A. Donenfeld)
- Fix Clang -Wforward warning in LKDTM (Justin Stitt)
- Fix comment to correctly refer to STRICT_DEVMEM (Lukas Bulwahn)
- Introduce dm-verity binding logic to LoadPin LSM (Matthias Kaehlcke)
- Clean up warnings and overflow and KASAN tests (Kees Cook)
* tag 'hardening-v5.20-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux:
dm: verity-loadpin: Drop use of dm_table_get_num_targets()
kasan: test: Silence GCC 12 warnings
drivers: lkdtm: fix clang -Wformat warning
x86: mm: refer to the intended config STRICT_DEVMEM in a comment
dm: verity-loadpin: Use CONFIG_SECURITY_LOADPIN_VERITY for conditional compilation
LoadPin: Enable loading from trusted dm-verity devices
dm: Add verity helpers for LoadPin
stack: Declare {randomize_,}kstack_offset to fix Sparse warnings
lib: overflow: Do not define 64-bit tests on 32-bit
MAINTAINERS: Add a general "kernel hardening" section
usercopy: use unsigned long instead of uintptr_t
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LoadPin limits loading of kernel modules, firmware and certain
other files to a 'pinned' file system (typically a read-only
rootfs). To provide more flexibility LoadPin is being extended
to also allow loading these files from trusted dm-verity
devices. For that purpose LoadPin can be provided with a list
of verity root digests that it should consider as trusted.
Add a bunch of helpers to allow LoadPin to check whether a DM
device is a trusted verity device. The new functions broadly
fall in two categories: those that need access to verity
internals (like the root digest), and the 'glue' between
LoadPin and verity. The new file dm-verity-loadpin.c contains
the glue functions.
Signed-off-by: Matthias Kaehlcke <mka@chromium.org>
Acked-by: Mike Snitzer <snitzer@kernel.org>
Link: https://lore.kernel.org/lkml/20220627083512.v7.1.I3e928575a23481121e73286874c4c2bdb403355d@changeid
Signed-off-by: Kees Cook <keescook@chromium.org>
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