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random: Simplify implementation of php_random_generate_fallback_seed() #13761

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Merged
merged 1 commit into from
Mar 20, 2024
Merged

random: Simplify implementation of php_random_generate_fallback_seed() #13761

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66 changes: 28 additions & 38 deletions ext/random/random.c
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Original file line number Diff line number Diff line change
Expand Up @@ -614,30 +614,12 @@ PHP_FUNCTION(random_int)
}
/* }}} */

static void write_32(PHP_SHA1_CTX *c, uint32_t u)
{
unsigned char buf[4];
unsigned char *p = buf;
*(p++) = (u >> 0) & 0xff;
*(p++) = (u >> 8) & 0xff;
*(p++) = (u >> 16) & 0xff;
*(p++) = (u >> 24) & 0xff;
PHP_SHA1Update(c, buf, sizeof(buf));
}

static void write_64(PHP_SHA1_CTX *c, uint64_t u)
{
write_32(c, u);
write_32(c, u >> 32);
}

static void write_p(PHP_SHA1_CTX *c, uintptr_t p)
{
if (sizeof(p) == 4) {
write_32(c, p);
} else {
write_64(c, p);
}
static inline void fallback_seed_add(PHP_SHA1_CTX *c, void *p, size_t l){
/* Wrapper around PHP_SHA1Update allowing to pass
* arbitrary pointers without (unsigned char*) casts
* everywhere.
*/
PHP_SHA1Update(c, p, l);
}

uint64_t php_random_generate_fallback_seed(void)
Expand All @@ -650,47 +632,55 @@ uint64_t php_random_generate_fallback_seed(void)
*/
PHP_SHA1_CTX c;
struct timeval tv;
void *pointer;
pid_t pid;
#ifdef ZTS
THREAD_T tid;
#endif
char buf[64 + 1];

PHP_SHA1Init(&c);
if (!RANDOM_G(fallback_seed_initialized)) {
/* Current time. */
gettimeofday(&tv, NULL);
write_32(&c, tv.tv_sec);
write_32(&c, tv.tv_usec);
fallback_seed_add(&c, &tv, sizeof(tv));
/* Various PIDs. */
write_32(&c, getpid());
pid = getpid();
fallback_seed_add(&c, &pid, sizeof(pid));
#ifndef WIN32
write_32(&c, getppid());
pid = getppid();
fallback_seed_add(&c, &pid, sizeof(pid));
#endif
#ifdef ZTS
write_32(&c, tsrm_thread_id());
tid = tsrm_thread_id();
fallback_seed_add(&c, &tid, sizeof(tid));
#endif
/* Pointer values to benefit from ASLR. */
write_p(&c, (uintptr_t)&RANDOM_G(fallback_seed_initialized));
write_p(&c, (uintptr_t)&c);
pointer = &RANDOM_G(fallback_seed_initialized);
fallback_seed_add(&c, &pointer, sizeof(pointer));
pointer = &c;
fallback_seed_add(&c, &pointer, sizeof(pointer));
/* Updated time. */
gettimeofday(&tv, NULL);
write_32(&c, tv.tv_usec);
fallback_seed_add(&c, &tv, sizeof(tv));
/* Hostname. */
memset(buf, 0, sizeof(buf));
if (gethostname(buf, sizeof(buf) - 1) == 0) {
PHP_SHA1Update(&c, (unsigned char*)buf, strlen(buf));
fallback_seed_add(&c, buf, strlen(buf));
}
/* CSPRNG. */
if (php_random_bytes_silent(buf, 16) == SUCCESS) {
PHP_SHA1Update(&c, (unsigned char*)buf, 16);
fallback_seed_add(&c, buf, 16);
}
/* Updated time. */
gettimeofday(&tv, NULL);
write_32(&c, tv.tv_usec);
fallback_seed_add(&c, &tv, sizeof(tv));
} else {
/* Current time. */
gettimeofday(&tv, NULL);
write_32(&c, tv.tv_sec);
write_32(&c, tv.tv_usec);
fallback_seed_add(&c, &tv, sizeof(tv));
/* Previous state. */
PHP_SHA1Update(&c, RANDOM_G(fallback_seed), 20);
fallback_seed_add(&c, RANDOM_G(fallback_seed), 20);
}
PHP_SHA1Final(RANDOM_G(fallback_seed), &c);
RANDOM_G(fallback_seed_initialized) = true;
Expand Down