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

crypto: ahash - Set default reqsize from ahash_alg

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

[ Upstream commit 9e01aaa1033d6e40f8d7cf4f20931a61ce9e3f04 ] Add a reqsize field to struct ahash_alg and use it to set the default reqsize so that algorithms with a static reqsize are not forced to create an init_tfm function. 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

Revert "crypto: remove CONFIG_CRYPTO_STATS"

2024-03-13T01:49:37+00:00

This reverts commit 2beb81fbf0c01a62515a1bcef326168494ee2bd0. While removing CONFIG_CRYPTO_STATS is a worthy goal, this also removed unrelated infrastructure such as crypto_comp_alg_common. Signed-off-by: Herbert Xu

crypto: remove CONFIG_CRYPTO_STATS

2024-03-01T10:35:40+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 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. Cc: Corentin Labbe Signed-off-by: Eric Biggers Acked-by: Ard Biesheuvel Acked-by: Corentin Labbe Signed-off-by: Herbert Xu

crypto: ahash - unexport crypto_hash_alg_has_setkey()

2024-02-02T10:10:05+00:00

Since crypto_hash_alg_has_setkey() is only called from ahash.c itself, make it a static function. Signed-off-by: Eric Biggers Signed-off-by: Herbert Xu

crypto: ahash - Set using_shash for cloned ahash wrapper over shash

2023-11-07T08:44:36+00:00

The cloned child of ahash that uses shash under the hood should use shash helpers (like crypto_shash_setkey()). The following panic may be observed on TCP-AO selftests: > ================================================================== > BUG: KASAN: wild-memory-access in crypto_mod_get+0x1b/0x60 > Write of size 4 at addr 5d5be0ff5c415e14 by task connect_ipv4/1397 > > CPU: 0 PID: 1397 Comm: connect_ipv4 Tainted: G W 6.6.0+ #47 > Call Trace: > > dump_stack_lvl+0x46/0x70 > kasan_report+0xc3/0xf0 > kasan_check_range+0xec/0x190 > crypto_mod_get+0x1b/0x60 > crypto_spawn_alg+0x53/0x140 > crypto_spawn_tfm2+0x13/0x60 > hmac_init_tfm+0x25/0x60 > crypto_ahash_setkey+0x8b/0x100 > tcp_ao_add_cmd+0xe7a/0x1120 > do_tcp_setsockopt+0x5ed/0x12a0 > do_sock_setsockopt+0x82/0x100 > __sys_setsockopt+0xe9/0x160 > __x64_sys_setsockopt+0x60/0x70 > do_syscall_64+0x3c/0xe0 > entry_SYSCALL_64_after_hwframe+0x46/0x4e > ================================================================== > general protection fault, probably for non-canonical address 0x5d5be0ff5c415e14: 0000 [#1] PREEMPT SMP KASAN > CPU: 0 PID: 1397 Comm: connect_ipv4 Tainted: G B W 6.6.0+ #47 > Call Trace: > > ? die_addr+0x3c/0xa0 > ? exc_general_protection+0x144/0x210 > ? asm_exc_general_protection+0x22/0x30 > ? add_taint+0x26/0x90 > ? crypto_mod_get+0x20/0x60 > ? crypto_mod_get+0x1b/0x60 > ? ahash_def_finup_done1+0x58/0x80 > crypto_spawn_alg+0x53/0x140 > crypto_spawn_tfm2+0x13/0x60 > hmac_init_tfm+0x25/0x60 > crypto_ahash_setkey+0x8b/0x100 > tcp_ao_add_cmd+0xe7a/0x1120 > do_tcp_setsockopt+0x5ed/0x12a0 > do_sock_setsockopt+0x82/0x100 > __sys_setsockopt+0xe9/0x160 > __x64_sys_setsockopt+0x60/0x70 > do_syscall_64+0x3c/0xe0 > entry_SYSCALL_64_after_hwframe+0x46/0x4e > > RIP: 0010:crypto_mod_get+0x20/0x60 Make sure that the child/clone has using_shash set when parent is an shash user. Fixes: 2f1f34c1bf7b ("crypto: ahash - optimize performance when wrapping shash") Cc: David Ahern Cc: "David S. Miller" Cc: Dmitry Safonov <0x7f454c46@gmail.com> Cc: Eric Biggers Cc: Eric Dumazet Cc: Francesco Ruggeri To: Herbert Xu Cc: Jakub Kicinski Cc: Paolo Abeni Cc: Salam Noureddine Cc: netdev@vger.kernel.org Cc: linux-crypto@vger.kernel.org Cc: linux-kernel@vger.kernel.org Signed-off-by: Dmitry Safonov Reviewed-by: Eric Biggers Signed-off-by: Herbert Xu

crypto: ahash - optimize performance when wrapping shash

2023-10-27T10:04:30+00:00

The "ahash" API provides access to both CPU-based and hardware offload- based implementations of hash algorithms. Typically the former are implemented as "shash" algorithms under the hood, while the latter are implemented as "ahash" algorithms. The "ahash" API provides access to both. Various kernel subsystems use the ahash API because they want to support hashing hardware offload without using a separate API for it. Yet, the common case is that a crypto accelerator is not actually being used, and ahash is just wrapping a CPU-based shash algorithm. This patch optimizes the ahash API for that common case by eliminating the extra indirect call for each ahash operation on top of shash. It also fixes the double-counting of crypto stats in this scenario (though CONFIG_CRYPTO_STATS should *not* be enabled by anyone interested in performance anyway...), and it eliminates redundant checking of CRYPTO_TFM_NEED_KEY. As a bonus, it also shrinks struct crypto_ahash. Signed-off-by: Eric Biggers Signed-off-by: Herbert Xu

crypto: ahash - check for shash type instead of not ahash type

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

Since the previous patch made crypto_shash_type visible to ahash.c, change checks for '->cra_type != &crypto_ahash_type' to '->cra_type == &crypto_shash_type'. This makes more sense and avoids having to forward-declare crypto_ahash_type. The result is still the same, since the type is either shash or ahash here. Signed-off-by: Eric Biggers Signed-off-by: Herbert Xu

crypto: hash - move "ahash wrapping shash" functions to ahash.c

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

The functions that are involved in implementing the ahash API on top of an shash algorithm belong better in ahash.c, not in shash.c where they currently are. Move them. Signed-off-by: Eric Biggers Signed-off-by: Herbert Xu

crypto: ahash - improve file comment

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

Improve the file comment for crypto/ahash.c. Signed-off-by: Eric Biggers Signed-off-by: Herbert Xu