Remove support for the "Crypto usage statistics" feature
(CONFIG_CRYPTO_STATS). This feature does not appear to have ever been
used, and it is harmful because it significantly reduces performance and
is a large maintenance burden.
Covering each of these points in detail:
1. Feature is not being used
Since these generic crypto statistics are only readable using netlink,
it's fairly straightforward to look for programs that use them. I'm
unable to find any evidence that any such programs exist. For example,
Debian Code Search returns no hits except the kernel header and kernel
code itself and translations of the kernel header:
https://codesearch.debian.net/search?q=CRYPTOCFGA_STAT&literal=1&perpkg=1
The patch series that added this feature in 2018
(https://lore.kernel.org/linux-crypto/1537351855-16618-1-git-send-email-clabbe@baylibre.com/)
said "The goal is to have an ifconfig for crypto device." This doesn't
appear to have happened.
It's not clear that there is real demand for crypto statistics. Just
because the kernel provides other types of statistics such as I/O and
networking statistics and some people find those useful does not mean
that crypto statistics are useful too.
Further evidence that programs are not using CONFIG_CRYPTO_STATS is that
it was able to be disabled in RHEL and Fedora as a bug fix
(https://gitlab.com/redhat/centos-stream/src/kernel/centos-stream-9/-/merge_requests/2947).
Even further evidence comes from the fact that there are and have been
bugs in how the stats work, but they were never reported. For example,
before Linux v6.7 hash stats were double-counted in most cases.
There has also never been any documentation for this feature, so it
might be hard to use even if someone wanted to.
2. CONFIG_CRYPTO_STATS significantly reduces performance
Enabling CONFIG_CRYPTO_STATS significantly reduces the performance of
the crypto API, even if no program ever retrieves the statistics. This
primarily affects systems with a large number of CPUs. For example,
https://bugs.launchpad.net/ubuntu/+source/linux/+bug/2039576 reported
that Lustre client encryption performance improved from 21.7GB/s to
48.2GB/s by disabling CONFIG_CRYPTO_STATS.
It can be argued that this means that CONFIG_CRYPTO_STATS should be
optimized with per-cpu counters similar to many of the networking
counters. But no one has done this in 5+ years. This is consistent
with the fact that the feature appears to be unused, so there seems to
be little interest in improving it as opposed to just disabling it.
It can be argued that because CONFIG_CRYPTO_STATS is off by default,
performance doesn't matter. But Linux distros tend to error on the side
of enabling options. The option is enabled in Ubuntu and Arch Linux,
and until recently was enabled in RHEL and Fedora (see above). So, even
just having the option available is harmful to users.
3. CONFIG_CRYPTO_STATS is a large maintenance burden
There are over 1000 lines of code associated with CONFIG_CRYPTO_STATS,
spread among 32 files. It significantly complicates much of the
implementation of the crypto API. After the initial submission, many
fixes and refactorings have consumed effort of multiple people to keep
this feature "working". We should be spending this effort elsewhere.
Acked-by: Ard Biesheuvel <ardb@kernel.org>
Acked-by: Corentin Labbe <clabbe@baylibre.com>
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
acomp's users might want to know if acomp is really async to optimize
themselves. One typical user which can benefit from exposed async stat is
zswap.
In zswap, zsmalloc is the most commonly used allocator for (and perhaps
the only one). For zsmalloc, we cannot sleep while we map the compressed
memory, so we copy it to a temporary buffer. By knowing the alg won't
sleep can help zswap to avoid the need for a buffer. This shows
noticeable improvement in load/store latency of zswap.
Link: https://lkml.kernel.org/r/20240222081135.173040-2-21cnbao@gmail.com
Signed-off-by: Barry Song <v-songbaohua@oppo.com>
Acked-by: Herbert Xu <herbert@gondor.apana.org.au>
Acked-by: Chris Li <chrisl@kernel.org>
Cc: Chengming Zhou <zhouchengming@bytedance.com>
Cc: Dan Streetman <ddstreet@ieee.org>
Cc: David S. Miller <davem@davemloft.net>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Nhat Pham <nphamcs@gmail.com>
Cc: Seth Jennings <sjenning@redhat.com>
Cc: Vitaly Wool <vitaly.wool@konsulko.com>
Cc: Yosry Ahmed <yosryahmed@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Move all stat code specific to acomp into the acomp code.
While we're at it, change the stats so that bytes and counts
are always incremented even in case of error. This allows the
reference counting to be removed as we can now increment the
counters prior to the operation.
After the operation we simply increase the error count if necessary.
This is safe as errors can only occur synchronously (or rather,
the existing code already ignored asynchronous errors which are
only visible to the callback function).
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
The request flags for acompress is split into two parts. Part of
it may be set by the user while the other part (ALLOC_OUTPUT) is
managed by the API.
This patch makes the split more explicit by not touching the other
bits at all in the two "set" functions that let the user modify the
flags.
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
The acomp API allows to send requests with a NULL destination buffer. In
this case, the algorithm implementation needs to allocate the
destination scatter list, perform the operation and return the buffer to
the user. For decompression, data is likely to expand and be bigger
than the allocated buffer.
Define the maximum size (128KB) that acomp implementations will allocate
for decompression operations as destination buffer when they receive a
request with a NULL destination buffer.
Suggested-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: Giovanni Cabiddu <giovanni.cabiddu@intel.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Given that crypto_alloc_tfm() may return ERR pointers, and to avoid
crashes on obscure error paths where such pointers are presented to
crypto_destroy_tfm() (such as [0]), add an ERR_PTR check there
before dereferencing the second argument as a struct crypto_tfm
pointer.
[0] https://lore.kernel.org/linux-crypto/000000000000de949705bc59e0f6@google.com/
Reported-by: syzbot+12cf5fbfdeba210a89dd@syzkaller.appspotmail.com
Reviewed-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
For a Linux server with NUMA, there are possibly multiple (de)compressors
which are either local or remote to some NUMA node. Some drivers will
automatically use the (de)compressor near the CPU calling acomp_alloc().
However, it is not necessarily correct because users who send acomp_req
could be from different NUMA node with the CPU which allocates acomp.
Just like kernel has kmalloc() and kmalloc_node(), here crypto can have
same support.
Cc: Seth Jennings <sjenning@redhat.com>
Cc: Dan Streetman <ddstreet@ieee.org>
Cc: Vitaly Wool <vitaly.wool@konsulko.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Signed-off-by: Barry Song <song.bao.hua@hisilicon.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
users may call crypto_has_acomp to confirm the existence of acomp before using
crypto_acomp APIs. Right now, many acomp have scomp backend, for example, lz4,
lzo, deflate etc. crypto_has_acomp will return false for them even though they
support acomp APIs.
Signed-off-by: Barry Song <song.bao.hua@hisilicon.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Based on 1 normalized pattern(s):
this program is free software you can redistribute it and or modify
it under the terms of the gnu general public license as published by
the free software foundation either version 2 of the license or at
your option any later version
extracted by the scancode license scanner the SPDX license identifier
GPL-2.0-or-later
has been chosen to replace the boilerplate/reference in 3029 file(s).
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Allison Randal <allison@lohutok.net>
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190527070032.746973796@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
All crypto_stats functions use the struct xxx_request for feeding stats,
but in some case this structure could already be freed.
For fixing this, the needed parameters (len and alg) will be stored
before the request being executed.
Fixes: cac5818c25d0 ("crypto: user - Implement a generic crypto statistics")
Reported-by: syzbot <syzbot+6939a606a5305e9e9799@syzkaller.appspotmail.com>
Signed-off-by: Corentin Labbe <clabbe@baylibre.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
All the 32-bit fields need to be 64-bit. In some cases, UINT32_MAX crypto
operations can be done in seconds.
Reported-by: Eric Biggers <ebiggers@kernel.org>
Signed-off-by: Corentin Labbe <clabbe@baylibre.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
This patch implement a generic way to get statistics about all crypto
usages.
Signed-off-by: Corentin Labbe <clabbe@baylibre.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Add a synchronous back-end (scomp) to acomp. This allows to easily
expose the already present compression algorithms in LKCF via acomp.
Signed-off-by: Giovanni Cabiddu <giovanni.cabiddu@intel.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Add acomp, an asynchronous compression api that uses scatterlist
buffers.
Signed-off-by: Giovanni Cabiddu <giovanni.cabiddu@intel.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
