kernel/linux.git/crypto/skcipher.c, branch v6.12.80

crypto: skcipher - Zap type in crypto_alloc_sync_skcipher

2025-05-29T09:02:40+00:00

[ Upstream commit ee509efc74ddbc59bb5d6fd6e050f9ef25f74bff ] The type needs to be zeroed as otherwise the user could use it to allocate an asynchronous sync skcipher. Signed-off-by: Herbert Xu Signed-off-by: Sasha Levin

crypto: remove CONFIG_CRYPTO_STATS

2024-04-02T02:49:38+00:00

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 Acked-by: Corentin Labbe Signed-off-by: Eric Biggers Signed-off-by: Herbert Xu

crypto: skcipher - Make use of internal state

2023-12-08T03:59:46+00:00

This patch adds code to the skcipher/lskcipher API to make use of the internal state if present. In particular, the skcipher lskcipher wrapper will allocate a buffer for the IV/state and feed that to the underlying lskcipher algorithm. Signed-off-by: Herbert Xu

crypto: skcipher - fix weak key check for lskciphers

2023-10-20T05:39:26+00:00

When an algorithm of the new "lskcipher" type is exposed through the "skcipher" API, calls to crypto_skcipher_setkey() don't pass on the CRYPTO_TFM_REQ_FORBID_WEAK_KEYS flag to the lskcipher. This causes self-test failures for ecb(des), as weak keys are not rejected anymore. Fix this. Fixes: 31865c4c4db2 ("crypto: skcipher - Add lskcipher") Signed-off-by: Eric Biggers Signed-off-by: Herbert Xu

crypto: skcipher - Add lskcipher

2023-09-20T05:15:29+00:00

Add a new API type lskcipher designed for taking straight kernel pointers instead of SG lists. Its relationship to skcipher will be analogous to that between shash and ahash. Signed-off-by: Herbert Xu

crypto: api - Fix CRYPTO_USER checks for report function

2023-05-02T10:22:24+00:00

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 Signed-off-by: Herbert Xu

crypto: api - Check CRYPTO_USER instead of NET for report

2023-03-14T09:06:42+00:00

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

crypto: skcipher - Count error stats differently

2023-03-14T09:06:42+00:00

Move all stat code specific to skcipher into the skcipher 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

crypto: skcipher - Use scatterwalk (un)map interface for dst and src buffers

2023-01-13T04:11:18+00:00

The skcipher walk API implementation avoids scatterwalk_map() for mapping the source and destination buffers, and invokes kmap_atomic() directly if the buffer in question is not in low memory (which can only happen on 32-bit architectures). This avoids some overhead on 64-bit architectures, and most notably, permits the skcipher code to run with preemption enabled. Now that scatterwalk_map() has been updated to use kmap_local(), none of this is needed, so we can simply use scatterwalk_map/unmap instead. Signed-off-by: Ard Biesheuvel Signed-off-by: Herbert Xu

crypto: skcipher - Allow sync algorithms with large request contexts

2022-11-18T08:59:34+00:00

Some sync algorithms may require a large amount of temporary space during its operations. There is no reason why they should be limited just because some legacy users want to place all temporary data on the stack. Such algorithms can now set a flag to indicate that they need extra request context, which will cause them to be invisible to users that go through the sync_skcipher interface. Signed-off-by: Herbert Xu