kernel/linux.git/crypto/af_alg.c, branch v7.2-rc1

crypto: af_alg - Drop support for off-CPU cryptography

2026-05-29T06:05:30+00:00

AF_ALG is deprecated and exposed to unprivileged userspace. Only use the least buggy algorithm implementations: the pure software ones. This removes one of the main advantages of AF_ALG, which is the ability to use it with off-CPU accelerators. However, using off-CPU accelerators has huge overheads, both in performance and attack surface. I have yet to see real-world, performance-critical workloads where using an accelerator via AF_ALG is actually a win over doing cryptography in userspace. If using an off-CPU accelerator really does turn out to be a win, a new API should be developed that is actually a good fit for it. Signed-off-by: Demi Marie Obenour Signed-off-by: Herbert Xu

net: Remove support for AIO on sockets

2026-05-29T06:05:30+00:00

The only user of msg->msg_iocb was AF_ALG, but that's deprecated. It can be removed entirely at the cost of only supporting synchronous operations. This doesn't break userspace, which will silently block (for a bounded amount of time) in io_submit instead of operating asynchronously. This also makes struct msghdr smaller, helping every other caller of sendmsg(). Signed-off-by: Demi Marie Obenour Acked-by: Jakub Kicinski Signed-off-by: Herbert Xu

crypto: af_alg - Cap AEAD AD length to 0x80000000

2026-05-15T10:08:37+00:00

In order to prevent arithmetic overflows when checking the TX buffer size, cap the associated data length to 0x80000000. Reported-by: Yiming Qian Fixes: 400c40cf78da ("crypto: algif - add AEAD support") Signed-off-by: Herbert Xu

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

2026-05-15T10:08:37+00:00

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

Merge tag 'v7.1-p1' of git://git.kernel.org/pub/scm/linux/kernel/git/herbert/crypto-2.6

2026-04-15T22:22:26+00:00

Pull crypto update from Herbert Xu: "API: - Replace crypto_get_default_rng with crypto_stdrng_get_bytes - Remove simd skcipher support - Allow algorithm types to be disabled when CRYPTO_SELFTESTS is off Algorithms: - Remove CPU-based des/3des acceleration - Add test vectors for authenc(hmac(md5),cbc({aes,des})) and authenc(hmac({md5,sha1,sha224,sha256,sha384,sha512}),rfc3686(ctr(aes))) - Replace spin lock with mutex in jitterentropy Drivers: - Add authenc algorithms to safexcel - Add support for zstd in qat - Add wireless mode support for QAT GEN6 - Add anti-rollback support for QAT GEN6 - Add support for ctr(aes), gcm(aes), and ccm(aes) in dthev2" * tag 'v7.1-p1' of git://git.kernel.org/pub/scm/linux/kernel/git/herbert/crypto-2.6: (129 commits) crypto: af_alg - use sock_kmemdup in alg_setkey_by_key_serial crypto: vmx - remove CRYPTO_DEV_VMX from Kconfig crypto: omap - convert reqctx buffer to fixed-size array crypto: atmel-sha204a - add Thorsten Blum as maintainer crypto: atmel-ecc - add Thorsten Blum as maintainer crypto: qat - fix IRQ cleanup on 6xxx probe failure crypto: geniv - Remove unused spinlock from struct aead_geniv_ctx crypto: qce - simplify qce_xts_swapiv() crypto: hisilicon - Fix dma_unmap_single() direction crypto: talitos - rename first/last to first_desc/last_desc crypto: talitos - fix SEC1 32k ahash request limitation crypto: jitterentropy - replace long-held spinlock with mutex crypto: hisilicon - remove unused and non-public APIs for qm and sec crypto: hisilicon/qm - drop redundant variable initialization crypto: hisilicon/qm - remove else after return crypto: hisilicon/qm - add const qualifier to info_name in struct qm_cmd_dump_item crypto: hisilicon - fix the format string type error crypto: ccree - fix a memory leak in cc_mac_digest() crypto: qat - add support for zstd crypto: qat - use swab32 macro ...

crypto: af_alg - use sock_kmemdup in alg_setkey_by_key_serial

2026-04-12T08:47:10+00:00

Replace sock_kmalloc() followed by memcpy() with sock_kmemdup() to simplify alg_setkey_by_key_serial(). Signed-off-by: Thorsten Blum Signed-off-by: Herbert Xu

crypto: af_alg - Fix page reassignment overflow in af_alg_pull_tsgl

2026-04-12T05:38:19+00:00

When page reassignment was added to af_alg_pull_tsgl the original loop wasn't updated so it may try to reassign one more page than necessary. Add the check to the reassignment so that this does not happen. Also update the comment which still refers to the obsolete offset argument. Reported-by: syzbot+d23888375c2737c17ba5@syzkaller.appspotmail.com Fixes: e870456d8e7c ("crypto: algif_skcipher - overhaul memory management") Signed-off-by: Herbert Xu

crypto: af_alg - limit RX SG extraction by receive buffer budget

2026-04-03T00:54:14+00:00

Make af_alg_get_rsgl() limit each RX scatterlist extraction to the remaining receive buffer budget. af_alg_get_rsgl() currently uses af_alg_readable() only as a gate before extracting data into the RX scatterlist. Limit each extraction to the remaining af_alg_rcvbuf(sk) budget so that receive-side accounting matches the amount of data attached to the request. If skcipher cannot obtain enough RX space for at least one chunk while more data remains to be processed, reject the recvmsg call instead of rounding the request length down to zero. Fixes: e870456d8e7c8d57c059ea479b5aadbb55ff4c3a ("crypto: algif_skcipher - overhaul memory management") Reported-by: Yifan Wu Reported-by: Juefei Pu Co-developed-by: Yuan Tan Signed-off-by: Yuan Tan Suggested-by: Xin Liu Signed-off-by: Douya Le Signed-off-by: Ren Wei Signed-off-by: Herbert Xu

crypto: algif_aead - Revert to operating out-of-place

2026-03-31T08:11:47+00:00

This mostly reverts commit 72548b093ee3 except for the copying of the associated data. There is no benefit in operating in-place in algif_aead since the source and destination come from different mappings. Get rid of all the complexity added for in-place operation and just copy the AD directly. Fixes: 72548b093ee3 ("crypto: algif_aead - copy AAD from src to dst") Reported-by: Taeyang Lee <0wn@theori.io> Signed-off-by: Herbert Xu

crypto: af-alg - fix NULL pointer dereference in scatterwalk

2026-03-26T09:10:58+00:00

The AF_ALG interface fails to unmark the end of a Scatter/Gather List (SGL) when chaining a new af_alg_tsgl structure. If a sendmsg() fills an SGL exactly to MAX_SGL_ENTS, the last entry is marked as the end. A subsequent sendmsg() allocates a new SGL and chains it, but fails to clear the end marker on the previous SGL's last data entry. This causes the crypto scatterwalk to hit a premature end, returning NULL on sg_next() and leading to a kernel panic during dereference. Fix this by explicitly unmarking the end of the previous SGL when performing sg_chain() in af_alg_alloc_tsgl(). Fixes: 8ff590903d5f ("crypto: algif_skcipher - User-space interface for skcipher operations") Signed-off-by: Norbert Szetei Signed-off-by: Herbert Xu