kernel/linux.git/Documentation/crypto, branch v6.12.96

crypto: af_alg - Remove zero-copy support from skcipher and aead

2026-07-18T14:52:11+00:00

commit ffdd2bc378953b525aca61902534e753f1f8e734 upstream. The zero-copy support is one of the riskiest aspects of AF_ALG. It allows userspace to request cryptographic operations directly on pagecache pages of files like the 'su' binary. It also allows userspace to concurrently modify the memory which is being operated on, a recipe for TOCTOU vulnerabilities. While zero-copy support is more valuable in other areas of the kernel like the frequently used networking and file I/O code, it has far less value in AF_ALG, which is a niche UAPI. AF_ALG primarily just exists for backwards compatibility with a small set of userspace programs such as 'iwd' that haven't yet been fixed to use userspace crypto code. Originally AF_ALG was intended to be used to access hardware crypto accelerators. However, it isn't an efficient interface for that anyway, and it turned out to be rarely used in this way in practice. Thus, the risks of the zero-copy support in AF_ALG vastly outweigh its benefits. Let's just remove it. This commit removes it from the "skcipher" and "aead" algorithm types. "hash" will be handled separately. This is a soft break, not a hard break. Even after this commit, it still works to use splice() or sendfile() to transfer data to an AF_ALG request socket from a pipe or any file, respectively. What changes is just that the kernel now makes an internal, stable copy of the data before doing the crypto operation. So performance is slightly reduced, but the UAPI isn't broken. And, very importantly, it's much safer. Tested with libkcapi/test.sh. All its test cases still pass. I also verified that this would have prevented the copy.fail exploit as well. I also used a custom test program to verify that sendfile() still works. Fixes: 8ff590903d5f ("crypto: algif_skcipher - User-space interface for skcipher operations") Fixes: 400c40cf78da ("crypto: algif - add AEAD support") Reported-by: Taeyang Lee <0wn@theori.io> Link: https://copy.fail/ Reported-by: Feng Ning Closes: https://lore.kernel.org/r/afYcc-tZFwvZZo76@ans-MacBook-Pro.local Reviewed-by: Demi Marie Obenour Cc: stable@vger.kernel.org Signed-off-by: Eric Biggers Signed-off-by: Herbert Xu Signed-off-by: Greg Kroah-Hartman

docs: crypto: async-tx-api: fix broken code example

2024-06-12T21:41:09+00:00

The code example fails to compile: 1) addr_conv is defined twice, once as a VLA, which have been phased out 2) submit is not a pointer, but is still dereferenced with -> 3) The first call to async_xor() lacked the trailing semicolon Fix these issues and while at it, fix some code style nitpicks as well: 1) make the functions static as users are unlikely to export them 2) include the relevant header 3) Shorten the example a bit by removing a redundant variable definition Fixes: 04ce9ab385dc ("async_xor: permit callers to pass in a 'dma/page scribble' region") Signed-off-by: Ahmad Fatoum Reviewed-by: Andre Noll Signed-off-by: Jonathan Corbet Link: https://lore.kernel.org/r/20240529-async-dma-docs-v2-1-8faf87e72e6d@pengutronix.de

Merge tag 'docs-6.8' of git://git.lwn.net/linux

2024-01-12T03:46:52+00:00

Pull documentation update from Jonathan Corbet: "Another moderately busy cycle for documentation, including: - The minimum Sphinx requirement has been raised to 2.4.4, following a warning that was added in 6.2 - Some reworking of the Documentation/process front page to, hopefully, make it more useful - Various kernel-doc tweaks to, for example, make it deal properly with __counted_by annotations - We have also restored a warning for documentation of nonexistent structure members that disappeared a while back. That had the delightful consequence of adding some 600 warnings to the docs build. A sustained effort by Randy, Vegard, and myself has addressed almost all of those, bringing the documentation back into sync with the code. The fixes are going through the appropriate maintainer trees - Various improvements to the HTML rendered docs, including automatic links to Git revisions and a nice new pulldown to make translations easy to access - Speaking of translations, more of those for Spanish and Chinese ... plus the usual stream of documentation updates and typo fixes" * tag 'docs-6.8' of git://git.lwn.net/linux: (57 commits) MAINTAINERS: use tabs for indent of CONFIDENTIAL COMPUTING THREAT MODEL A reworked process/index.rst ring-buffer/Documentation: Add documentation on buffer_percent file Translated the RISC-V architecture boot documentation. Docs: remove mentions of fdformat from util-linux Docs/zh_CN: Fix the meaning of DEBUG to pr_debug() Documentation: move driver-api/dcdbas to userspace-api/ Documentation: move driver-api/isapnp to userspace-api/ Documentation/core-api : fix typo in workqueue Documentation/trace: Fixed typos in the ftrace FLAGS section kernel-doc: handle a void function without producing a warning scripts/get_abi.pl: ignore some temp files docs: kernel_abi.py: fix command injection scripts/get_abi: fix source path leak CREDITS, MAINTAINERS, docs/process/howto: Update man-pages' maintainer docs: translations: add translations links when they exist kernel-doc: Align quick help and the code MAINTAINERS: add reviewer for Spanish translations docs: ignore __counted_by attribute in structure definitions scripts: kernel-doc: Clarify missing struct member description ..

crypto: octeontx2 - add devlink option to set t106 mode

2023-12-29T03:25:38+00:00

On CN10KA B0/CN10KB, CPT scatter gather format has modified to support multi-seg in inline IPsec. Due to this CPT requires new firmware and doesn't work with CN10KA0/A1 firmware. To make HW works in backward compatibility mode or works with CN10KA0/A1 firmware, a bit(T106_MODE) is introduced in HW CSR. This patch adds devlink parameter for configuring T106_MODE. This patch also documents the devlink parameter under Documentation/crypto/device_drivers. Signed-off-by: Srujana Challa Signed-off-by: Herbert Xu

Merge branch 'vegard' into docs-mw

2023-11-17T20:07:51+00:00

Vegard Nossum writes: This patch series replaces some instances of 'class:: toc-title' with toctree's :caption: attribute, see the last patch in the series for some more rationale/explanation.

crypto: doc: properly format ToC headings

2023-11-17T20:05:26+00:00

"class:: toc-title" was a workaround for older Sphinx versions that are no longer supported. The canonical way to add a heading to the ToC is to use :caption:. Do that. Cc: Mauro Carvalho Chehab Cc: Stephan Mueller Signed-off-by: Vegard Nossum Signed-off-by: Jonathan Corbet Link: https://lore.kernel.org/r/20231027081830.195056-5-vegard.nossum@oracle.com

crypto: ahash - remove support for nonzero alignmask

2023-10-27T10:04:29+00:00

Currently, the ahash API checks the alignment of all key and result buffers against the algorithm's declared alignmask, and for any unaligned buffers it falls back to manually aligned temporary buffers. This is virtually useless, however. First, since it does not apply to the message, its effect is much more limited than e.g. is the case for the alignmask for "skcipher". Second, the key and result buffers are given as virtual addresses and cannot (in general) be DMA'ed into, so drivers end up having to copy to/from them in software anyway. As a result it's easy to use memcpy() or the unaligned access helpers. The crypto_hash_walk_*() helper functions do use the alignmask to align the message. But with one exception those are only used for shash algorithms being exposed via the ahash API, not for native ahashes, and aligning the message is not required in this case, especially now that alignmask support has been removed from shash. The exception is the n2_core driver, which doesn't set an alignmask. In any case, no ahash algorithms actually set a nonzero alignmask anymore. Therefore, remove support for it from ahash. The benefit is that all the code to handle "misaligned" buffers in the ahash API goes away, reducing the overhead of the ahash API. This follows the same change that was made to shash. Signed-off-by: Eric Biggers Signed-off-by: Herbert Xu

docs: crypto: async-tx-api: fix typo in struct name

2023-06-09T07:59:30+00:00

Add missing underscore. Signed-off-by: Baruch Siach Link: https://lore.kernel.org/r/2ef9dfaa33c1eff019e6fe43fe738700c2230b3d.1685342291.git.baruch@tkos.co.il Signed-off-by: Jonathan Corbet

Docs/subsystem-apis: Remove '[The ]Linux' prefixes from titles of listed documents

2023-01-24T22:27:08+00:00

Some documents that listed on subsystem-apis have 'Linux' or 'The Linux' title prefixes. It's duplicated information, and makes finding the document of interest with human eyes not easy. Remove the prefixes from the titles. Signed-off-by: SeongJae Park Acked-by: Iwona Winiarska Acked-by: Bjorn Helgaas Link: https://lore.kernel.org/r/20230122184834.181977-1-sj@kernel.org Signed-off-by: Jonathan Corbet

crypto: doc - use correct function name

2022-11-04T09:35:44+00:00

The hashing API does not have a function called .finish() Signed-off-by: Ralph Siemsen Signed-off-by: Herbert Xu