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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>
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Checking the config via ifdef incorrectly compiles out the report
functions when CRYPTO_USER is set to =m. Fix it by using IS_ENABLED()
instead.
Fixes: c0f9e01dd266 ("crypto: api - Check CRYPTO_USER instead of NET for report")
Signed-off-by: Ondrej Mosnacek <omosnace@redhat.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
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The report function is currently conditionalised on CONFIG_NET.
As it's only used by CONFIG_CRYPTO_USER, conditionalising on that
instead of CONFIG_NET makes more sense.
This gets rid of a rarely used code-path.
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
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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>
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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>
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Some of the algorithm unregistration functions return -ENOENT when asked
to unregister a non-registered algorithm, while others always return 0
or always return void. But no users check the return value, except for
two of the bulk unregistration functions which print a message on error
but still always return 0 to their caller, and crypto_del_alg() which
calls crypto_unregister_instance() which always returns 0.
Since unregistering a non-registered algorithm is always a kernel bug
but there isn't anything callers should do to handle this situation at
runtime, let's simplify things by making all the unregistration
functions return void, and moving the error message into
crypto_unregister_alg() and upgrading it to a WARN().
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
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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>
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There have been a pretty ridiculous number of issues with initializing
the report structures that are copied to userspace by NETLINK_CRYPTO.
Commit 4473710df1f8 ("crypto: user - Prepare for CRYPTO_MAX_ALG_NAME
expansion") replaced some strncpy()s with strlcpy()s, thereby
introducing information leaks. Later two other people tried to replace
other strncpy()s with strlcpy() too, which would have introduced even
more information leaks:
- https://lore.kernel.org/patchwork/patch/954991/
- https://patchwork.kernel.org/patch/10434351/
Commit cac5818c25d0 ("crypto: user - Implement a generic crypto
statistics") also uses the buggy strlcpy() approach and therefore leaks
uninitialized memory to userspace. A fix was proposed, but it was
originally incomplete.
Seeing as how apparently no one can get this right with the current
approach, change all the reporting functions to:
- Start by memsetting the report structure to 0. This guarantees it's
always initialized, regardless of what happens later.
- Initialize all strings using strscpy(). This is safe after the
memset, ensures null termination of long strings, avoids unnecessary
work, and avoids the -Wstringop-truncation warnings from gcc.
- Use sizeof(var) instead of sizeof(type). This is more robust against
copy+paste errors.
For simplicity, also reuse the -EMSGSIZE return value from nla_put().
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
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Add crypto_register_acomps and crypto_unregister_acomps to allow
the registration of multiple implementations with one call.
Signed-off-by: Giovanni Cabiddu <giovanni.cabiddu@intel.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
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Continuing from this commit: 52f5684c8e1e
("kernel: use macros from compiler.h instead of __attribute__((...))")
I submitted 4 total patches. They are part of task I've taken up to
increase compiler portability in the kernel. I've cleaned up the
subsystems under /kernel /mm /block and /security, this patch targets
/crypto.
There is <linux/compiler.h> which provides macros for various gcc specific
constructs. Eg: __weak for __attribute__((weak)). I've cleaned all
instances of gcc specific attributes with the right macros for the crypto
subsystem.
I had to make one additional change into compiler-gcc.h for the case when
one wants to use this: __attribute__((aligned) and not specify an alignment
factor. From the gcc docs, this will result in the largest alignment for
that data type on the target machine so I've named the macro
__aligned_largest. Please advise if another name is more appropriate.
Signed-off-by: Gideon Israel Dsouza <gidisrael@gmail.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
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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>
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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>
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Eric Biggers
Ondrej Mosnacek
Herbert Xu
Barry Song
Thomas Gleixner
Giovanni Cabiddu
Gideon Israel Dsouza
