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wolfcrypt/src/rng_bank.c:

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* refactor rng_bank.refcount management using wolfSSL_RefInc_IfAtLeast() and wolfSSL_RefDec_IfEquals(), to mitigate deallocation races.
* in wc_rng_bank_init(), fail fast for non-retryable errors.
* in wc_rng_bank_init(), wc_rng_bank_checkout(), and wc_rng_bank_inst_reinit(), consistently treat timeout_secs==0 as dont-wait, and timeout_secs<0 as wait-forever if wc_rng_bank_init() or flags & WC_RNG_BANK_FLAG_CAN_WAIT.
* in wc_rng_bank_checkout(), fix affinity dynamics to recompute after possible sleep, or drop affinity attempts entirely if using WC_RNG_BANK_FLAG_CAN_FAIL_OVER_INST strategy.
This commit is contained in:
Daniel Pouzzner
2026-07-07 00:18:42 -05:00
parent 0fdceafe6b
commit 5cee8bec39
1 changed files with 211 additions and 98 deletions
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wolfcrypt/src/rng_bank.c
+211 -98
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@@ -71,6 +71,10 @@
((rng_ptr)->drbg == NULL)
#endif
/* To disable retry looping in wc_rng_bank_init(), pass timeout_secs=0, and to
* retry indefinitely, pass negative timeout_secs -- the flags arg here is only
* used to initialize the flags in the new bank.
*/
WOLFSSL_API int wc_rng_bank_init(
struct wc_rng_bank *ctx,
int n_rngs,
@@ -133,6 +137,22 @@ WOLFSSL_API int wc_rng_bank_init(
WC_RELAX_LONG_LOOP();
if (ret == 0)
break;
/* Several plausible error codes are non-retryable -- fail early
* for these.
*/
switch (ret) {
case WC_NO_ERR_TRACE(BAD_MUTEX_E):
case WC_NO_ERR_TRACE(BAD_FUNC_ARG):
case WC_NO_ERR_TRACE(MEMORY_E):
case WC_NO_ERR_TRACE(NOT_COMPILED_IN):
case WC_NO_ERR_TRACE(MISSING_RNG_E):
case WC_NO_ERR_TRACE(BUFFER_E):
case WC_NO_ERR_TRACE(OPEN_RAN_E):
case WC_NO_ERR_TRACE(FIPS_NOT_ALLOWED_E):
goto out;
}
/* Allow interrupt only if we're stuck spinning retries -- i.e.,
* don't allow an untimely user signal to derail an
* initialization that is proceeding expeditiously.
@@ -141,7 +161,7 @@ WOLFSSL_API int wc_rng_bank_init(
if (ret == WC_NO_ERR_TRACE(INTERRUPTED_E))
break;
ts2 = XTIME(0);
if (ts2 - ts1 > timeout_secs) {
if ((timeout_secs >= 0) && (ts2 - ts1 > timeout_secs)) {
ret = WC_TIMEOUT_E;
break;
}
@@ -160,6 +180,8 @@ WOLFSSL_API int wc_rng_bank_init(
}
}
out:
if (ret != 0)
(void)wc_rng_bank_fini(ctx);
@@ -220,6 +242,8 @@ WOLFSSL_API int wc_rng_bank_set_affinity_handlers(
WOLFSSL_API int wc_rng_bank_fini(struct wc_rng_bank *ctx) {
int i;
int ret;
WC_ATOMIC_INT_ARG new_refcount;
if (ctx == NULL)
return BAD_FUNC_ARG;
@@ -235,6 +259,18 @@ WOLFSSL_API int wc_rng_bank_fini(struct wc_rng_bank *ctx) {
else if (wolfSSL_RefCur(ctx->refcount) < 1)
return BAD_STATE_E;
wolfSSL_RefDec_IfEquals(&ctx->refcount, 1, &new_refcount, &ret);
if (ret != 0) {
#ifdef WC_VERBOSE_RNG
WOLFSSL_DEBUG_PRINTF(
"WARNING: wc_rng_bank_fini() called with refcount %d.", new_refcount);
#endif
if (new_refcount > 1)
return BUSY_E;
else
return ret;
}
#ifndef WC_RNG_BANK_STATIC
if (ctx->rngs)
#endif
@@ -247,7 +283,13 @@ WOLFSSL_API int wc_rng_bank_fini(struct wc_rng_bank *ctx) {
"BUG: wc_rng_bank_fini() called with RNG #%d still "
"locked.\n", i);
#endif
return BUSY_E;
wolfSSL_RefInc2(&ctx->refcount, &new_refcount, &ret);
/* Always return BAD_STATE_E here -- a locked rng with a zero
* refcount on the bank is always a corruption.
*/
(void)new_refcount;
(void)ret;
return BAD_STATE_E;
}
}
@@ -313,22 +355,19 @@ WOLFSSL_API int wc_rng_bank_default_set(struct wc_rng_bank *bank) {
if (bank == NULL)
return BAD_FUNC_ARG;
if ((! (bank->flags & WC_RNG_BANK_FLAG_INITED)) ||
(wolfSSL_RefCur(bank->refcount) < 1))
{
if (! (bank->flags & WC_RNG_BANK_FLAG_INITED))
return BAD_STATE_E;
}
wolfSSL_RefInc2(&bank->refcount, &new_refcount, &ret);
if (ret != 0)
return ret;
wolfSSL_RefInc_IfAtLeast(&bank->refcount, 1, &new_refcount, &ret);
if (ret != 0) {
#ifdef WC_VERBOSE_RNG
if (new_refcount < 2)
WOLFSSL_DEBUG_PRINTF(
"BUG: wc_rng_bank_default_set() new_refcount %d.\n", new_refcount);
"BUG: wc_rng_bank_default_set() with refcount %d.\n", new_refcount);
#else
(void)new_refcount;
(void)new_refcount;
#endif
return ret;
}
if (wolfSSL_Atomic_Ptr_CompareExchange((void * volatile *)&default_rng_bank, (void **)&cur_default_rng_bank, bank))
return 0;
else {
@@ -351,13 +390,19 @@ WOLFSSL_API int wc_rng_bank_default_set(struct wc_rng_bank *bank) {
WOLFSSL_API int wc_rng_bank_default_checkout(struct wc_rng_bank **bank) {
int ret;
struct wc_rng_bank *cur_default_rng_bank = default_rng_bank;
WC_ATOMIC_INT_ARG new_refcount;
if (bank == NULL)
return BAD_FUNC_ARG;
if (cur_default_rng_bank == NULL)
return BAD_STATE_E;
wolfSSL_RefInc(&cur_default_rng_bank->refcount, &ret);
if (ret == 0)
*bank = cur_default_rng_bank;
wolfSSL_RefInc_IfAtLeast(&cur_default_rng_bank->refcount, 2, &new_refcount, &ret);
if (ret != 0)
return ret;
*bank = cur_default_rng_bank;
return ret;
}
@@ -431,6 +476,7 @@ WOLFSSL_API int wc_rng_bank_checkout(
int ret = 0;
time_t ts1, ts2;
int n_rngs_tried = 0;
WC_ATOMIC_INT_ARG new_refcount;
#ifdef WC_RNG_BANK_DEFAULT_SUPPORT
if (bank == NULL)
@@ -460,45 +506,16 @@ WOLFSSL_API int wc_rng_bank_checkout(
return BAD_FUNC_ARG;
}
if (flags & WC_RNG_BANK_FLAG_AFFINITY_LOCK) {
if ((bank->affinity_lock_cb == NULL) ||
(bank->affinity_unlock_cb == NULL))
{
/* Increment bank->refcount here speculatively, and assert on the resulting
* refcount, to mitigate races with bank deallocation.
*/
wolfSSL_RefInc_IfAtLeast(&bank->refcount, 1, &new_refcount, &ret);
if (ret != 0) {
#ifdef WC_VERBOSE_RNG
WOLFSSL_DEBUG_PRINTF(
"BUG: wc_rng_bank_checkout() called with _AFFINITY_LOCK but "
"missing _lock_cb.\n");
WOLFSSL_DEBUG_PRINTF(
"wc_rng_bank_checkout() called with refcount %d.\n", new_refcount);
#endif
return BAD_FUNC_ARG;
}
ret = bank->affinity_lock_cb(bank->cb_arg);
if (ret == 0)
new_lock_value |= WC_RNG_BANK_INST_LOCK_AFFINITY_LOCKED;
else if (ret != WC_NO_ERR_TRACE(ALREADY_E))
return ret;
}
if (flags & WC_RNG_BANK_FLAG_PREFER_AFFINITY_INST) {
preferred_inst_offset = -1;
ret = bank->affinity_get_id_cb(bank->cb_arg, &preferred_inst_offset);
if (ret != 0) {
#ifdef WC_VERBOSE_RNG
WOLFSSL_DEBUG_PRINTF(
"BUG: bank->affinity_get_id_cb() returned err %d.\n", ret);
#endif
}
else if (((preferred_inst_offset < 0) ||
(preferred_inst_offset >= bank->n_rngs)))
{
ret = BAD_INDEX_E;
}
}
else {
if ((preferred_inst_offset < 0) ||
(preferred_inst_offset >= bank->n_rngs))
{
ret = BAD_INDEX_E;
}
return ret;
}
if ((timeout_secs > 0) && (flags & WC_RNG_BANK_FLAG_CAN_WAIT))
@@ -509,6 +526,46 @@ WOLFSSL_API int wc_rng_bank_checkout(
for (; ret == 0;) {
int expected = 0;
if (flags & WC_RNG_BANK_FLAG_AFFINITY_LOCK) {
if ((bank->affinity_lock_cb == NULL) ||
(bank->affinity_unlock_cb == NULL))
{
#ifdef WC_VERBOSE_RNG
WOLFSSL_DEBUG_PRINTF(
"BUG: wc_rng_bank_checkout() called with _AFFINITY_LOCK but "
"missing _lock_cb.\n");
#endif
ret = BAD_FUNC_ARG;
break;
}
ret = bank->affinity_lock_cb(bank->cb_arg);
if (ret == 0)
new_lock_value |= WC_RNG_BANK_INST_LOCK_AFFINITY_LOCKED;
else if (ret == WC_NO_ERR_TRACE(ALREADY_E))
ret = 0;
else
break;
}
if (flags & WC_RNG_BANK_FLAG_PREFER_AFFINITY_INST) {
preferred_inst_offset = -1;
ret = bank->affinity_get_id_cb(bank->cb_arg, &preferred_inst_offset);
if (ret != 0) {
#ifdef WC_VERBOSE_RNG
WOLFSSL_DEBUG_PRINTF(
"BUG: bank->affinity_get_id_cb() returned err %d.\n", ret);
#endif
break;
}
}
if ((preferred_inst_offset < 0) ||
(preferred_inst_offset >= bank->n_rngs))
{
ret = BAD_INDEX_E;
break;
}
if (wolfSSL_Atomic_Int_CompareExchange(
&bank->rngs[preferred_inst_offset].lock,
&expected,
@@ -523,6 +580,7 @@ WOLFSSL_API int wc_rng_bank_checkout(
(n_rngs_tried < bank->n_rngs))
{
WOLFSSL_ATOMIC_STORE((*rng_inst)->lock, WC_RNG_BANK_INST_LOCK_FREE);
*rng_inst = NULL;
}
else {
#ifdef WC_VERBOSE_RNG
@@ -544,65 +602,102 @@ WOLFSSL_API int wc_rng_bank_checkout(
*/
#endif
#ifdef WOLFSSL_USE_SAVE_VECTOR_REGISTERS
if ((flags | bank->flags) & WC_RNG_BANK_FLAG_NO_VECTOR_OPS) {
if (DISABLE_VECTOR_REGISTERS() == 0)
ret = DISABLE_VECTOR_REGISTERS();
if (ret == 0)
WOLFSSL_ATOMIC_STORE((*rng_inst)->lock, new_lock_value |
WC_RNG_BANK_INST_LOCK_VEC_OPS_INH);
else if (ret == WC_NO_ERR_TRACE(WC_ACCEL_INHIBIT_E))
ret = 0;
else {
WOLFSSL_ATOMIC_STORE((*rng_inst)->lock, WC_RNG_BANK_INST_LOCK_FREE);
*rng_inst = NULL;
break;
}
}
#endif /* WOLFSSL_USE_SAVE_VECTOR_REGISTERS */
return 0; /* Short-circuit return, holding onto RNG and affinity
* locks and vector register inhibition.
return 0; /* Short-circuit return, holding onto bank refcount,
* RNG lock, affinity locks, and (if applicable)
* vector register inhibition.
*/
}
}
if (flags & WC_RNG_BANK_FLAG_CAN_FAIL_OVER_INST) {
if ((! (flags & WC_RNG_BANK_FLAG_CAN_WAIT)) &&
(n_rngs_tried >= bank->n_rngs))
if ((n_rngs_tried >= bank->n_rngs) &&
((! (flags & WC_RNG_BANK_FLAG_CAN_WAIT)) ||
(timeout_secs == 0)))
{
ret = BUSY_E;
break; /* jump to cleanup. */
}
/* There's no longer any consistent connection between the CPU ID
* and the instance -- no point getting an affinity lock.
*/
flags &= ~(word32)WC_RNG_BANK_FLAG_AFFINITY_LOCK;
flags &= ~(word32)WC_RNG_BANK_FLAG_PREFER_AFFINITY_INST;
++preferred_inst_offset;
if (preferred_inst_offset >= bank->n_rngs)
preferred_inst_offset = 0;
++n_rngs_tried;
}
else {
if (! (flags & WC_RNG_BANK_FLAG_CAN_WAIT)) {
if ((! (flags & WC_RNG_BANK_FLAG_CAN_WAIT)) ||
(timeout_secs == 0))
{
ret = BUSY_E;
break; /* jump to cleanup. */
}
}
if (flags & WC_RNG_BANK_FLAG_AFFINITY_LOCK)
if (new_lock_value & WC_RNG_BANK_INST_LOCK_AFFINITY_LOCKED) {
(void)bank->affinity_unlock_cb(bank->cb_arg);
ret = WC_CHECK_FOR_INTR_SIGNALS();
if (ret == WC_NO_ERR_TRACE(INTERRUPTED_E))
return ret; /* immediate return -- no locks held */
if (timeout_secs > 0) {
ts2 = XTIME(0);
if (ts2 - ts1 >= timeout_secs)
return WC_TIMEOUT_E; /* immediate return -- no locks held */
}
WC_RELAX_LONG_LOOP();
if (flags & WC_RNG_BANK_FLAG_AFFINITY_LOCK) {
ret = bank->affinity_lock_cb(bank->cb_arg);
if (ret)
return ret; /* immediate return -- no locks held */
new_lock_value &= ~WC_RNG_BANK_INST_LOCK_AFFINITY_LOCKED;
}
/* Note that we may have been migrated at this point, but it doesn't
* matter -- we only reach this point if we have to retry/iterate.
*/
if ((flags & WC_RNG_BANK_FLAG_CAN_WAIT) && (timeout_secs != 0)) {
ret = WC_CHECK_FOR_INTR_SIGNALS();
if (ret == WC_NO_ERR_TRACE(INTERRUPTED_E))
break;
if (timeout_secs > 0) {
ts2 = XTIME(0);
if (ts2 - ts1 >= timeout_secs) {
ret = WC_TIMEOUT_E;
break;
}
}
WC_RELAX_LONG_LOOP();
}
}
if (flags & WC_RNG_BANK_FLAG_AFFINITY_LOCK)
if (ret == 0)
ret = RNG_FAILURE_E;
if (new_lock_value & WC_RNG_BANK_INST_LOCK_AFFINITY_LOCKED)
(void)bank->affinity_unlock_cb(bank->cb_arg);
/* Decrement the speculative refcount increment. */
{
int refdec_err;
wolfSSL_RefDec2(&bank->refcount, &new_refcount, &refdec_err);
#ifdef WC_VERBOSE_RNG
if (refdec_err != 0)
WOLFSSL_DEBUG_PRINTF(
"WARNING: wc_rng_bank_checkout() cleanup wolfSSL_RefDec2 returned %d.", refdec_err);
else if (new_refcount <= 0)
WOLFSSL_DEBUG_PRINTF(
"WARNING: wc_rng_bank_checkout() bank refcount after wolfSSL_RefDec2() is %d.", new_refcount);
#else
(void)new_refcount;
(void)refdec_err;
#endif
}
return ret;
}
@@ -670,9 +765,28 @@ WOLFSSL_API int wc_rng_bank_checkin(
REENABLE_VECTOR_REGISTERS();
if (lockval & WC_RNG_BANK_INST_LOCK_AFFINITY_LOCKED)
return bank->affinity_unlock_cb(bank->cb_arg);
ret = bank->affinity_unlock_cb(bank->cb_arg);
else
return 0;
ret = 0;
{
WC_ATOMIC_INT_ARG new_refcount;
int refdec_err;
wolfSSL_RefDec2(&bank->refcount, &new_refcount, &refdec_err);
#ifdef WC_VERBOSE_RNG
if (refdec_err != 0)
WOLFSSL_DEBUG_PRINTF(
"WARNING: wc_rng_bank_checkin() wolfSSL_RefDec2 returned %d.", refdec_err);
else if (new_refcount <= 0)
WOLFSSL_DEBUG_PRINTF(
"WARNING: wc_rng_bank_checkin() bank refcount after wolfSSL_RefDec2() is %d.", new_refcount);
#else
(void)new_refcount;
(void)refdec_err;
#endif
}
return ret;
}
/* note the rng_inst passed to wc_rng_bank_inst_reinit() must have been obtained
@@ -720,7 +834,7 @@ WOLFSSL_API int wc_rng_bank_inst_reinit(
bank->heap, devId);
if (ret == 0)
break;
if (! (flags & WC_RNG_BANK_FLAG_CAN_WAIT)) {
if ((! (flags & WC_RNG_BANK_FLAG_CAN_WAIT)) || (timeout_secs == 0)) {
#ifdef WC_VERBOSE_RNG
WOLFSSL_DEBUG_PRINTF(
"WARNING: wc_rng_bank_inst_reinit() returning err %d.\n", ret);
@@ -849,20 +963,22 @@ WOLFSSL_API int wc_rng_bank_reseed(struct wc_rng_bank *bank,
(word32)sizeof(scratch));
if (ret == 0)
break;
if ((timeout_secs <= 0) ||
if ((timeout_secs == 0) ||
(! (flags & WC_RNG_BANK_FLAG_CAN_WAIT)))
{
break;
}
ts2 = XTIME(0);
if (ts2 - ts1 > timeout_secs) {
if (timeout_secs > 0) {
ts2 = XTIME(0);
if (ts2 - ts1 > timeout_secs) {
#ifdef WC_VERBOSE_RNG
WOLFSSL_DEBUG_PRINTF(
"ERROR: timeout after attempted reseed by "
"wc_RNG_GenerateBlock() for DRBG #%d, err %d.", n, ret);
WOLFSSL_DEBUG_PRINTF(
"ERROR: timeout after attempted reseed by "
"wc_RNG_GenerateBlock() for DRBG #%d, err %d.", n, ret);
#endif
ret = WC_TIMEOUT_E;
break;
ret = WC_TIMEOUT_E;
break;
}
}
}
#ifdef WC_VERBOSE_RNG
@@ -892,6 +1008,7 @@ WOLFSSL_API int wc_rng_bank_reseed(struct wc_rng_bank *bank,
WOLFSSL_API int wc_InitRng_BankRef(struct wc_rng_bank *bank, WC_RNG *rng)
{
int ret;
WC_ATOMIC_INT_ARG new_refcount;
#ifdef WC_RNG_BANK_DEFAULT_SUPPORT
if (bank == NULL)
@@ -904,19 +1021,15 @@ WOLFSSL_API int wc_InitRng_BankRef(struct wc_rng_bank *bank, WC_RNG *rng)
return BAD_FUNC_ARG;
}
if ((! (bank->flags & WC_RNG_BANK_FLAG_INITED)) ||
(wolfSSL_RefCur(bank->refcount) < 1))
{
if (! (bank->flags & WC_RNG_BANK_FLAG_INITED))
return BAD_STATE_E;
}
XMEMSET(rng, 0, sizeof(*rng));
wolfSSL_RefInc(&bank->refcount, &ret);
wolfSSL_RefInc_IfAtLeast(&bank->refcount, 1, &new_refcount, &ret);
(void)new_refcount;
if (ret != 0)
return ret;
XMEMSET(rng, 0, sizeof(*rng));
rng->heap = bank->heap;
rng->status = WC_DRBG_BANKREF;
rng->bankref = bank;