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Adhemerval Zanella Netto 6f4e0fcfa2 stdlib: Add arc4random, arc4random_buf, and arc4random_uniform (BZ #4417) 
The implementation is based on scalar Chacha20 with per-thread cache.
It uses getrandom or /dev/urandom as fallback to get the initial entropy,
and reseeds the internal state on every 16MB of consumed buffer.

To improve performance and lower memory consumption the per-thread cache
is allocated lazily on first arc4random functions call, and if the
memory allocation fails getentropy or /dev/urandom is used as fallback.
The cache is also cleared on thread exit iff it was initialized (so if
arc4random is not called it is not touched).

Although it is lock-free, arc4random is still not async-signal-safe
(the per thread state is not updated atomically).

The ChaCha20 implementation is based on RFC8439 [1], omitting the final
XOR of the keystream with the plaintext because the plaintext is a
stream of zeros.  This strategy is similar to what OpenBSD arc4random
does.

The arc4random_uniform is based on previous work by Florian Weimer,
where the algorithm is based on Jérémie Lumbroso paper Optimal Discrete
Uniform Generation from Coin Flips, and Applications (2013) [2], who
credits Donald E. Knuth and Andrew C. Yao, The complexity of nonuniform
random number generation (1976), for solving the general case.

The main advantage of this method is the that the unit of randomness is not
the uniform random variable (uint32_t), but a random bit.  It optimizes the
internal buffer sampling by initially consuming a 32-bit random variable
and then sampling byte per byte.  Depending of the upper bound requested,
it might lead to better CPU utilization.

Checked on x86_64-linux-gnu, aarch64-linux, and powerpc64le-linux-gnu.

Co-authored-by: Florian Weimer <fweimer@redhat.com>
Reviewed-by: Yann Droneaud <ydroneaud@opteya.com>

[1] https://datatracker.ietf.org/doc/html/rfc8439
[2] https://arxiv.org/pdf/1304.1916.pdf
2022-07-22 11:58:27 -03:00
..
alloc_buffer_alloc_array.c Update copyright dates with scripts/update-copyrights 2022-01-01 11:40:24 -08:00
alloc_buffer_allocate.c Update copyright dates with scripts/update-copyrights 2022-01-01 11:40:24 -08:00
alloc_buffer_copy_bytes.c Update copyright dates with scripts/update-copyrights 2022-01-01 11:40:24 -08:00
alloc_buffer_copy_string.c Update copyright dates with scripts/update-copyrights 2022-01-01 11:40:24 -08:00
alloc_buffer_create_failure.c Update copyright dates with scripts/update-copyrights 2022-01-01 11:40:24 -08:00
arena.c Update copyright dates with scripts/update-copyrights 2022-01-01 11:40:24 -08:00
Depend added rt to malloc/Depend [BZ #27132] 2021-02-23 10:04:45 +01:00
dynarray-skeleton.c Update copyright dates with scripts/update-copyrights 2022-01-01 11:40:24 -08:00
dynarray.h Update copyright dates with scripts/update-copyrights 2022-01-01 11:40:24 -08:00
dynarray_at_failure.c Update copyright dates with scripts/update-copyrights 2022-01-01 11:40:24 -08:00
dynarray_emplace_enlarge.c Update copyright dates with scripts/update-copyrights 2022-01-01 11:40:24 -08:00
dynarray_finalize.c Update copyright dates with scripts/update-copyrights 2022-01-01 11:40:24 -08:00
dynarray_resize.c Update copyright dates with scripts/update-copyrights 2022-01-01 11:40:24 -08:00
dynarray_resize_clear.c Update copyright dates with scripts/update-copyrights 2022-01-01 11:40:24 -08:00
hooks.c Update copyright dates with scripts/update-copyrights 2022-01-01 11:40:24 -08:00
Makefile build: Properly generate .d dependency files [BZ #28922] 2022-02-25 10:35:45 -08:00
malloc-check.c malloc: Simplify checked_request2size interface 2022-07-05 11:04:45 +02:00
malloc-debug.c Update copyright dates with scripts/update-copyrights 2022-01-01 11:40:24 -08:00
malloc-internal.h Update copyright dates with scripts/update-copyrights 2022-01-01 11:40:24 -08:00
malloc.c malloc: Simplify implementation of __malloc_assert 2022-07-21 16:33:04 +02:00
malloc.h Update copyright dates with scripts/update-copyrights 2022-01-01 11:40:24 -08:00
mallocbug.c Reformat malloc to gnu style. 2014-01-02 09:40:10 +01:00
mcheck-impl.c Update copyright dates with scripts/update-copyrights 2022-01-01 11:40:24 -08:00
mcheck-init.c Update copyright dates with scripts/update-copyrights 2022-01-01 11:40:24 -08:00
mcheck.c Update copyright dates with scripts/update-copyrights 2022-01-01 11:40:24 -08:00
mcheck.h Update copyright dates with scripts/update-copyrights 2022-01-01 11:40:24 -08:00
memusage.c Update copyright dates with scripts/update-copyrights 2022-01-01 11:40:24 -08:00
memusage.sh Update copyright dates not handled by scripts/update-copyrights. 2022-01-01 11:42:26 -08:00
memusagestat.c Update copyright dates not handled by scripts/update-copyrights. 2022-01-01 11:42:26 -08:00
morecore.c Update copyright dates with scripts/update-copyrights 2022-01-01 11:40:24 -08:00
mtrace-impl.c Update copyright dates with scripts/update-copyrights 2022-01-01 11:40:24 -08:00
mtrace.c Update copyright dates with scripts/update-copyrights 2022-01-01 11:40:24 -08:00
mtrace.pl malloc: Remove LD_TRACE_PRELINKING usage from mtrace 2022-02-10 09:16:13 -03:00
obstack.c Update copyright dates with scripts/update-copyrights 2022-01-01 11:40:24 -08:00
obstack.h Update copyright dates with scripts/update-copyrights 2022-01-01 11:40:24 -08:00
reallocarray.c Update copyright dates with scripts/update-copyrights 2022-01-01 11:40:24 -08:00
scratch_buffer_dupfree.c Update copyright dates with scripts/update-copyrights 2022-01-01 11:40:24 -08:00
scratch_buffer_grow.c Update copyright dates with scripts/update-copyrights 2022-01-01 11:40:24 -08:00
scratch_buffer_grow_preserve.c Update copyright dates with scripts/update-copyrights 2022-01-01 11:40:24 -08:00
scratch_buffer_set_array_size.c Update copyright dates with scripts/update-copyrights 2022-01-01 11:40:24 -08:00
set-freeres.c Update copyright dates with scripts/update-copyrights 2022-01-01 11:40:24 -08:00
thread-freeres.c stdlib: Add arc4random, arc4random_buf, and arc4random_uniform (BZ #4417) 2022-07-22 11:58:27 -03:00
tst-alloc_buffer.c Update copyright dates with scripts/update-copyrights 2022-01-01 11:40:24 -08:00
tst-calloc.c Update copyright dates with scripts/update-copyrights 2022-01-01 11:40:24 -08:00
tst-compathooks-off.c Update copyright dates with scripts/update-copyrights 2022-01-01 11:40:24 -08:00
tst-compathooks-on.c Move malloc hooks into a compat DSO 2021-07-22 18:37:59 +05:30
tst-dynarray-at-fail.c Update copyright dates with scripts/update-copyrights 2022-01-01 11:40:24 -08:00
tst-dynarray-fail.c Update copyright dates with scripts/update-copyrights 2022-01-01 11:40:24 -08:00
tst-dynarray-shared.h Update copyright dates with scripts/update-copyrights 2022-01-01 11:40:24 -08:00
tst-dynarray.c Update copyright dates with scripts/update-copyrights 2022-01-01 11:40:24 -08:00
tst-free-errno.c Update copyright dates with scripts/update-copyrights 2022-01-01 11:40:24 -08:00
tst-interpose-aux-nothread.c Update copyright dates with scripts/update-copyrights 2022-01-01 11:40:24 -08:00
tst-interpose-aux-thread.c Update copyright dates with scripts/update-copyrights 2022-01-01 11:40:24 -08:00
tst-interpose-aux.c Update copyright dates with scripts/update-copyrights 2022-01-01 11:40:24 -08:00
tst-interpose-aux.h Update copyright dates with scripts/update-copyrights 2022-01-01 11:40:24 -08:00
tst-interpose-nothread.c Update copyright dates with scripts/update-copyrights 2022-01-01 11:40:24 -08:00
tst-interpose-skeleton.c Update copyright dates with scripts/update-copyrights 2022-01-01 11:40:24 -08:00
tst-interpose-static-nothread.c Update copyright dates with scripts/update-copyrights 2022-01-01 11:40:24 -08:00
tst-interpose-static-thread.c Update copyright dates with scripts/update-copyrights 2022-01-01 11:40:24 -08:00
tst-interpose-thread.c Update copyright dates with scripts/update-copyrights 2022-01-01 11:40:24 -08:00
tst-mallinfo2.c Update copyright dates with scripts/update-copyrights 2022-01-01 11:40:24 -08:00
tst-malloc-backtrace.c Avoid -Wuse-after-free in tests [BZ #26779]. 2022-01-26 10:38:23 -07:00
tst-malloc-check.c Avoid -Wuse-after-free in tests [BZ #26779]. 2022-01-26 10:38:23 -07:00
tst-malloc-fork-deadlock.c Update copyright dates with scripts/update-copyrights 2022-01-01 11:40:24 -08:00
tst-malloc-stats-cancellation.c malloc: Run tst-malloc-stats-cancellation via test-driver.c 2021-04-07 02:35:50 +02:00
tst-malloc-tcache-leak.c Update copyright dates with scripts/update-copyrights 2022-01-01 11:40:24 -08:00
tst-malloc-thread-exit.c Update copyright dates with scripts/update-copyrights 2022-01-01 11:40:24 -08:00
tst-malloc-thread-fail.c Update copyright dates with scripts/update-copyrights 2022-01-01 11:40:24 -08:00
tst-malloc-too-large.c Avoid -Wuse-after-free in tests [BZ #26779]. 2022-01-26 10:38:23 -07:00
tst-malloc-usable-tunables.c Initialize tunable list with the GLIBC_TUNABLES environment variable 2016-12-31 23:49:24 +05:30
tst-malloc-usable.c Update copyright dates with scripts/update-copyrights 2022-01-01 11:40:24 -08:00
tst-malloc.c Update copyright dates with scripts/update-copyrights 2022-01-01 11:40:24 -08:00
tst-malloc_info.c Update copyright dates with scripts/update-copyrights 2022-01-01 11:40:24 -08:00
tst-mallocalign1.c malloc: Fix tst-mallocalign1 macro spacing. 2022-02-01 11:05:26 -05:00
tst-mallocfork.c Fix malloc tests build with GCC 10. 2019-06-10 22:12:08 +00:00
tst-mallocfork2.c Update copyright dates with scripts/update-copyrights 2022-01-01 11:40:24 -08:00
tst-mallocfork3.c Update copyright dates with scripts/update-copyrights 2022-01-01 11:40:24 -08:00
tst-mallocstate.c Update copyright dates with scripts/update-copyrights 2022-01-01 11:40:24 -08:00
tst-mallopt.c Update copyright dates with scripts/update-copyrights 2022-01-01 11:40:24 -08:00
tst-memalign.c Update copyright dates with scripts/update-copyrights 2022-01-01 11:40:24 -08:00
tst-mtrace.c Update copyright dates with scripts/update-copyrights 2022-01-01 11:40:24 -08:00
tst-mtrace.sh Update copyright dates with scripts/update-copyrights 2022-01-01 11:40:24 -08:00
tst-mxfast.c Update copyright dates with scripts/update-copyrights 2022-01-01 11:40:24 -08:00
tst-obstack.c Avoid -Wuse-after-free in tests [BZ #26779]. 2022-01-26 10:38:23 -07:00
tst-posix_memalign.c Update copyright dates with scripts/update-copyrights 2022-01-01 11:40:24 -08:00
tst-pvalloc-fortify.c Update copyright dates with scripts/update-copyrights 2022-01-01 11:40:24 -08:00
tst-pvalloc.c Update copyright dates with scripts/update-copyrights 2022-01-01 11:40:24 -08:00
tst-realloc.c malloc: Exit early on test failure in tst-realloc 2022-03-10 08:50:51 +01:00
tst-reallocarray.c Update copyright dates with scripts/update-copyrights 2022-01-01 11:40:24 -08:00
tst-safe-linking.c Update copyright dates with scripts/update-copyrights 2022-01-01 11:40:24 -08:00
tst-scratch_buffer.c Update copyright dates with scripts/update-copyrights 2022-01-01 11:40:24 -08:00
tst-tcfree1.c Update copyright dates with scripts/update-copyrights 2022-01-01 11:40:24 -08:00
tst-tcfree2.c Update copyright dates with scripts/update-copyrights 2022-01-01 11:40:24 -08:00
tst-tcfree3.c Update copyright dates with scripts/update-copyrights 2022-01-01 11:40:24 -08:00
tst-trim1.c * malloc/tst-trim1.c: New file. 2007-12-16 22:57:57 +00:00
tst-valloc.c Update copyright dates with scripts/update-copyrights 2022-01-01 11:40:24 -08:00
Versions Move malloc_{g,s}et_state to libc_malloc_debug 2021-07-22 18:38:10 +05:30