kernel/linux.git/crypto/rng.c, branch v7.2-rc2

crypto: rng - Free default RNG on module exit

2026-06-12T01:56:45+00:00

When the rng module is removed the default RNG will be leaked. Call crypto_del_default_rng to free it if possible. Fixes: 7cecadb7cca8 ("crypto: rng - Do not free default RNG when it becomes unused") Signed-off-by: Herbert Xu

crypto: api - use designated initializers for report structs

2026-05-15T10:08:48+00:00

Use designated initializers for the report structs instead of clearing the struct with memset() and then copying fixed strings with strscpy() at runtime. This keeps the structs zero-initialized, lets the compiler diagnose oversized string literals, and makes the code easier to read. Signed-off-by: Thorsten Blum Signed-off-by: Herbert Xu

crypto: rng - Make crypto_stdrng_get_bytes() use normal RNG in non-FIPS mode

2026-04-03T00:56:12+00:00

"stdrng" is needed only in "FIPS mode". Therefore, make crypto_stdrng_get_bytes() delegate to either the normal Linux RNG or to "stdrng", depending on the current mode. This will eliminate the need to built the SP800-90A DRBG and its dependencies into CRYPTO_FIPS=n kernels. Signed-off-by: Eric Biggers Signed-off-by: Herbert Xu

crypto: rng - Unexport "default RNG" symbols

2026-04-03T00:56:12+00:00

Now that crypto_default_rng, crypto_get_default_rng(), and crypto_put_default_rng() have no users outside crypto/rng.c itself, unexport them and make them static. Signed-off-by: Eric Biggers Signed-off-by: Herbert Xu

crypto: rng - Add crypto_stdrng_get_bytes()

2026-04-03T00:56:11+00:00

All callers of crypto_get_default_rng() use the following sequence: crypto_get_default_rng() crypto_rng_get_bytes(crypto_default_rng, ...) crypto_put_default_rng() While it may have been intended that callers amortize the cost of getting and putting the "default RNG" (i.e. "stdrng") over multiple calls, in practice that optimization is never used. The callers just want a function that gets random bytes from the "stdrng". Therefore, add such a function: crypto_stdrng_get_bytes(). Importantly, this decouples the callers from the crypto_rng API. That allows a later commit to make this function simply call get_random_bytes_wait() unless the kernel is in "FIPS mode". Signed-off-by: Eric Biggers Signed-off-by: Herbert Xu

crypto: rng - Use unregister_rngs in register_rngs

2026-02-06T10:52:22+00:00

Replace the for loop with a call to crypto_unregister_rngs(). Return 'ret' immediately and remove the goto statement to simplify the error handling code. No functional changes. Signed-off-by: Thorsten Blum Signed-off-by: Herbert Xu

crypto: api - remove unnecessary forward declarations

2026-01-23T05:48:43+00:00

Add the __maybe_unused attribute to the function definitions and remove the now-unnecessary forward declarations. Signed-off-by: Thorsten Blum Signed-off-by: Herbert Xu

crypto: rng - Ensure set_ent is always present

2025-10-06T02:17:07+00:00

Ensure that set_ent is always set since only drbg provides it. Fixes: 77ebdabe8de7 ("crypto: af_alg - add extra parameters for DRBG interface") Reported-by: Yiqi Sun Signed-off-by: Herbert Xu

crypto: api - Add support for duplicating algorithms before registration

2025-04-16T07:36:24+00:00

If the bit CRYPTO_ALG_DUP_FIRST is set, an algorithm will be duplicated by kmemdup before registration. This is inteded for hardware-based algorithms that may be unplugged at will. Do not use this if the algorithm data structure is embedded in a bigger data structure. Perform the duplication in the driver instead. Signed-off-by: Herbert Xu

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