crc-t10dif: clean up some more things

- Correctly compare the algorithm name in crc_t10dif_notify().

- Use proper NOTIFY_* status codes instead of 0.

- Consistently use CRC_T10DIF_STRING instead of "crct10dif" directly.

- Use a proper type for the shash_desc context.

- Use crypto_shash_driver_name() instead of open-coding it.

- Make crc_t10dif_transform_show() use snprintf() rather than sprintf().
This isn't actually necessary since the buffer has size PAGE_SIZE
and CRYPTO_MAX_ALG_NAME < PAGE_SIZE, but it's good practice.

- Give the "transform" sysfs file mode 0444 rather than 0644,
since it doesn't implement a setter method.

- Adjust the module description to not be the same as crct10dif-generic.

Cc: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

crc-t10dif: use fallback in initial state

Currently the crc-t10dif module starts out with the fallback disabled
and crct10dif_tfm == NULL. crc_t10dif_mod_init() tries to allocate
crct10dif_tfm, and if it fails it enables the fallback.

This is backwards because it means that any call to crc_t10dif() prior
to module_init (which could theoretically happen from built-in code)
will crash rather than use the fallback as expected. Also, it means
that if the initial tfm allocation fails, then the fallback stays
permanently enabled even if a crct10dif implementation is loaded later.

Change it to use the more logical solution of starting with the fallback
enabled, and disabling the fallback when a tfm gets allocated for the
first time. This change also ends up simplifying the code.

Also take the opportunity to convert the code to use the new static_key
API, which is much less confusing than the old and deprecated one.

Cc: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

crc-t10dif: Fix potential crypto notify dead-lock

The crypto notify call occurs with a read mutex held so you must
not do any substantial work directly. In particular, you cannot
call crypto_alloc_* as they may trigger further notifications
which may dead-lock in the presence of another writer.

This patch fixes this by postponing the work into a work queue and
taking the same lock in the module init function.

While we're at it this patch also ensures that all RCU accesses are
marked appropriately (tested with sparse).

Finally this also reveals a race condition in module param show
function as it may be called prior to the module init function.
It's fixed by testing whether crct10dif_tfm is NULL (this is true
iff the init function has not completed assuming fallback is false).

Fixes: 11dcb1037f40 ("crc-t10dif: Allow current transform to be...")
Fixes: b76377543b73 ("crc-t10dif: Pick better transform if one...")
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Reviewed-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 230

Based on 2 normalized pattern(s):

this source code is licensed under the gnu general public license
version 2 see the file copying for more details

this source code is licensed under general public license version 2
see

extracted by the scancode license scanner the SPDX license identifier

GPL-2.0-only

has been chosen to replace the boilerplate/reference in 52 file(s).

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Enrico Weigelt <info@metux.net>
Reviewed-by: Allison Randal <allison@lohutok.net>
Reviewed-by: Alexios Zavras <alexios.zavras@intel.com>
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190602204653.449021192@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

crypto: shash - remove shash_desc::flags

The flags field in 'struct shash_desc' never actually does anything.
The only ostensibly supported flag is CRYPTO_TFM_REQ_MAY_SLEEP.
However, no shash algorithm ever sleeps, making this flag a no-op.

With this being the case, inevitably some users who can't sleep wrongly
pass MAY_SLEEP. These would all need to be fixed if any shash algorithm
actually started sleeping. For example, the shash_ahash_*() functions,
which wrap a shash algorithm with the ahash API, pass through MAY_SLEEP
from the ahash API to the shash API. However, the shash functions are
called under kmap_atomic(), so actually they're assumed to never sleep.

Even if it turns out that some users do need preemption points while
hashing large buffers, we could easily provide a helper function
crypto_shash_update_large() which divides the data into smaller chunks
and calls crypto_shash_update() and cond_resched() for each chunk. It's
not necessary to have a flag in 'struct shash_desc', nor is it necessary
to make individual shash algorithms aware of this at all.

Therefore, remove shash_desc::flags, and document that the
crypto_shash_*() functions can be called from any context.

Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

crc-t10dif: crc_t10dif_mutex can be static

Fixes: b76377543b73 ("crc-t10dif: Pick better transform if one becomes available")
Signed-off-by: kbuild test robot <fengguang.wu@intel.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

crc-t10dif: Allow current transform to be inspected in sysfs

Add a way to print the currently active CRC algorithm in:

/sys/module/crc_t10dif/parameters/transform

Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

crc-t10dif: Pick better transform if one becomes available

T10 CRC library is linked into the kernel thanks to block and SCSI. The
crypto accelerators are typically loaded later as modules and are
therefore not available when the T10 CRC library is initialized.

Use the crypto notifier facility to trigger a switch to a better algorithm
if one becomes available after the initial hash has been registered. Use
RCU to protect the original transform while the new one is being set up.

Suggested-by: Ard Biesheuvel <ard.biesheuvel@linaro.org
Suggested-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

lib: introduce crc_t10dif_update()

This introduces crc_t10dif_update() which enables to calculate CRC
for a block which straddles multiple SG elements by calling multiple
times. This also converts crc_t10dif() to use crc_t10dif_update() as
they are almost same.

(remove extra function call in crc_t10dif() and crc_t10dif_update -
Tim + Herbert)

Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
Acked-by: Martin K. Petersen <martin.petersen@oracle.com>
Cc: Tim Chen <tim.c.chen@linux.intel.com>
Cc: Herbert Xu <herbert@gondor.apana.org.au>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: linux-crypto@vger.kernel.org
Cc: Nicholas Bellinger <nab@linux-iscsi.org>
Cc: Sagi Grimberg <sagig@mellanox.com>
Cc: "Martin K. Petersen" <martin.petersen@oracle.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: "James E.J. Bottomley" <James.Bottomley@HansenPartnership.com>
Cc: target-devel@vger.kernel.org
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>

crypto: crct10dif - Add fallback for broken initrds

Unfortunately, even with a softdep some distros fail to include
the necessary modules in the initrd. Therefore this patch adds
a fallback path to restore existing behaviour where we cannot
load the new crypto crct10dif algorithm.

In order to do this, the underlying crct10dif has been split out
from the crypto implementation so that it can be used on the
fallback path.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

Reinstate "crypto: crct10dif - Wrap crc_t10dif function all to use crypto transform framework"

This patch reinstates commits
67822649d7305caf3dd50ed46c27b99c94eff996
39761214eefc6b070f29402aa1165f24d789b3f7
0b95a7f85718adcbba36407ef88bba0a7379ed03
31d939625a9a20b1badd2d4e6bf6fd39fa523405
2d31e518a42828df7877bca23a958627d60408bc

Now that module softdeps are in the kernel we can use that to resolve
the boot issue which cause the revert.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

Revert "crypto: crct10dif - Wrap crc_t10dif function all to use crypto transform framework"

This reverts commits
67822649d7305caf3dd50ed46c27b99c94eff996
39761214eefc6b070f29402aa1165f24d789b3f7
0b95a7f85718adcbba36407ef88bba0a7379ed03
31d939625a9a20b1badd2d4e6bf6fd39fa523405
2d31e518a42828df7877bca23a958627d60408bc

Unfortunately this change broke boot on some systems that used an
initrd which does not include the newly created crct10dif modules.
As these modules are required by sd_mod under certain configurations
this is a serious problem.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

crypto: crct10dif - Use PTR_RET

lib/crc-t10dif.c:42:1-3: WARNING: PTR_RET can be used

Use PTR_RET rather than if(IS_ERR(...)) + PTR_ERR

Generated by: coccinelle/api/ptr_ret.cocci

Reported-by: Fengguang Wu <fengguang.wu@intel.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

crypto: crct10dif - Wrap crc_t10dif function all to use crypto transform framework

When CRC T10 DIF is calculated using the crypto transform framework, we
wrap the crc_t10dif function call to utilize it. This allows us to
take advantage of any accelerated CRC T10 DIF transform that is
plugged into the crypto framework.

Signed-off-by: Tim Chen <tim.c.chen@linux.intel.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

[SCSI] lib: Add support for the T10 (SCSI) Data Integrity Field CRC

The SCSI Block Protocol uses this 16-bit CRC to verify the integrity
of each data sector. crc_t10dif() is used by sd_dif.c when performing
I/O to or from disks formatted with protection information.

Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>