boringssl/crypto/rand_extra/forkunsafe.c
Adam Langley 8e8f250422 Use thread-local storage for PRNG states if fork-unsafe buffering is enabled.
We switched from thread-local storage to a mutex-pool in 82639e6f53
because, for highly-threaded processes, the memory used by all the
states could be quite large. I had judged that a mutex-pool should be
fine, but had underestimated the PRNG requirements of some of our jobs.

This change makes rand.c support using either thread-locals or a
mutex-pool. Thread-locals are used if fork-unsafe buffering is enabled.
While not strictly related to fork-safety, we already have the
fork-unsafe control, and it's already set by jobs that care a lot about
PRNG performance, so fits quite nicely here.

Change-Id: Iaf1e0171c70d4c8dbe1e42283ea13df5b613cb2d
Reviewed-on: https://boringssl-review.googlesource.com/c/31564
Commit-Queue: Adam Langley <agl@google.com>
Reviewed-by: David Benjamin <davidben@google.com>
2018-12-28 18:05:18 +00:00

51 lines
1.7 KiB
C

/* Copyright (c) 2017, Google Inc.
*
* Permission to use, copy, modify, and/or distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
* SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION
* OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
* CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. */
#include <openssl/rand.h>
#include <stdlib.h>
#include "../fipsmodule/rand/internal.h"
// g_buffering_enabled is true if fork-unsafe buffering has been enabled.
static int g_buffering_enabled = 0;
static CRYPTO_once_t g_buffering_enabled_once = CRYPTO_ONCE_INIT;
static int g_buffering_enabled_pending = 0;
static void g_buffer_enabled_init(void) {
g_buffering_enabled = g_buffering_enabled_pending;
}
#if !defined(OPENSSL_WINDOWS)
void RAND_enable_fork_unsafe_buffering(int fd) {
// We no longer support setting the file-descriptor with this function.
if (fd != -1) {
abort();
}
g_buffering_enabled_pending = 1;
CRYPTO_once(&g_buffering_enabled_once, g_buffer_enabled_init);
if (g_buffering_enabled != 1) {
// RAND_bytes has been called before this function.
abort();
}
}
#endif
int rand_fork_unsafe_buffering_enabled(void) {
CRYPTO_once(&g_buffering_enabled_once, g_buffer_enabled_init);
return g_buffering_enabled;
}