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property: make cache flushing slight less deterministic

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If there is no timer available to seed the stochastic flushing, revert to a
global seed that gets updated each flush.

Reviewed-by: Tomas Mraz <tomas@openssl.org>
Reviewed-by: Matt Caswell <matt@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/18906)
This commit is contained in:
Pauli 2022-07-29 11:00:50 +10:00 committed by Matt Caswell
parent cd854f225b
commit 56d4ff6cd7
1 changed files with 12 additions and 2 deletions
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14
crypto/property/property.c
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@ -15,6 +15,7 @@
#include "internal/core.h"
#include "internal/property.h"
#include "internal/provider.h"
#include "internal/tsan_assist.h"
#include "crypto/ctype.h"
#include <openssl/lhash.h>
#include <openssl/rand.h>
@ -90,6 +91,7 @@ typedef struct {
LHASH_OF(QUERY) *cache;
size_t nelem;
uint32_t seed;
unsigned char using_global_seed;
} IMPL_CACHE_FLUSH;
DEFINE_SPARSE_ARRAY_OF(ALGORITHM);
@ -649,13 +651,21 @@ static void impl_cache_flush_one_alg(ossl_uintmax_t idx, ALGORITHM *alg,
static void ossl_method_cache_flush_some(OSSL_METHOD_STORE *store)
{
IMPL_CACHE_FLUSH state;
static TSAN_QUALIFIER uint32_t global_seed = 1;
state.nelem = 0;
if ((state.seed = OPENSSL_rdtsc()) == 0)
state.seed = 1;
state.using_global_seed = 0;
if ((state.seed = OPENSSL_rdtsc()) == 0) {
/* If there is no timer available, seed another way */
state.using_global_seed = 1;
state.seed = tsan_load(&global_seed);
}
store->cache_need_flush = 0;
ossl_sa_ALGORITHM_doall_arg(store->algs, &impl_cache_flush_one_alg, &state);
store->cache_nelem = state.nelem;
/* Without a timer, update the global seed */
if (state.using_global_seed)
tsan_add(&global_seed, state.seed);
}
int ossl_method_store_cache_get(OSSL_METHOD_STORE *store, OSSL_PROVIDER *prov,