prov: move the entropy source out of the FIPS provider

Reviewed-by: Matt Caswell <matt@openssl.org>
Reviewed-by: Matthias St. Pierre <Matthias.St.Pierre@ncp-e.com>
(Merged from https://github.com/openssl/openssl/pull/13226)

19 files changed, 276 insertions, 233 deletions

diff --git a/providers/common/build.info b/providers/common/build.info
index b6d56682a9..8de65f3fa8 100644
--- a/providers/common/build.info
+++ b/providers/common/build.info
@@ -2,6 +2,6 @@ SUBDIRS=der
 
 SOURCE[../libcommon.a]=provider_err.c provider_ctx.c
 $FIPSCOMMON=provider_util.c capabilities.c bio_prov.c digest_to_nid.c\
-            securitycheck.c
+            securitycheck.c provider_seeding.c
 SOURCE[../libnonfips.a]=$FIPSCOMMON securitycheck_default.c
 SOURCE[../libfips.a]=$FIPSCOMMON securitycheck_fips.c
diff --git a/providers/common/include/prov/providercommonerr.h b/providers/common/include/prov/providercommonerr.h
index 05ca8abef0..86a3667641 100644
--- a/providers/common/include/prov/providercommonerr.h
+++ b/providers/common/include/prov/providercommonerr.h
@@ -141,6 +141,7 @@ int ERR_load_PROV_strings(void);
 # define PROV_R_NO_PARAMETERS_SET                         177
 # define PROV_R_OPERATION_NOT_SUPPORTED_FOR_THIS_KEYTYPE  178
 # define PROV_R_OUTPUT_BUFFER_TOO_SMALL                   106
+# define PROV_R_PARENT_CANNOT_GENERATE_RANDOM_NUMBERS     228
 # define PROV_R_PARENT_LOCKING_NOT_ENABLED                182
 # define PROV_R_PARENT_STRENGTH_TOO_WEAK                  194
 # define PROV_R_PATH_MUST_BE_ABSOLUTE                     219
@@ -158,7 +159,6 @@ int ERR_load_PROV_strings(void);
 # define PROV_R_UNABLE_TO_FIND_CIPHERS                    207
 # define PROV_R_UNABLE_TO_GET_ENTROPY                     202
 # define PROV_R_UNABLE_TO_GET_NONCE                       203
-# define PROV_R_UNABLE_TO_GET_PARENT_RESEED_PROP_COUNTER  198
 # define PROV_R_UNABLE_TO_GET_PARENT_STRENGTH             199
 # define PROV_R_UNABLE_TO_INITIALISE_CIPHERS              208
 # define PROV_R_UNABLE_TO_LOAD_SHA1                       143
diff --git a/providers/common/provider_err.c b/providers/common/provider_err.c
index 2b65903a31..2915330b86 100644
--- a/providers/common/provider_err.c
+++ b/providers/common/provider_err.c
@@ -152,6 +152,8 @@ static const ERR_STRING_DATA PROV_str_reasons[] = {
     "operation not supported for this keytype"},
     {ERR_PACK(ERR_LIB_PROV, 0, PROV_R_OUTPUT_BUFFER_TOO_SMALL),
     "output buffer too small"},
+    {ERR_PACK(ERR_LIB_PROV, 0, PROV_R_PARENT_CANNOT_GENERATE_RANDOM_NUMBERS),
+    "parent cannot generate random numbers"},
     {ERR_PACK(ERR_LIB_PROV, 0, PROV_R_PARENT_LOCKING_NOT_ENABLED),
     "parent locking not enabled"},
     {ERR_PACK(ERR_LIB_PROV, 0, PROV_R_PARENT_STRENGTH_TOO_WEAK),
@@ -182,8 +184,6 @@ static const ERR_STRING_DATA PROV_str_reasons[] = {
     "unable to get entropy"},
     {ERR_PACK(ERR_LIB_PROV, 0, PROV_R_UNABLE_TO_GET_NONCE),
     "unable to get nonce"},
-    {ERR_PACK(ERR_LIB_PROV, 0, PROV_R_UNABLE_TO_GET_PARENT_RESEED_PROP_COUNTER),
-    "unable to get parent reseed prop counter"},
     {ERR_PACK(ERR_LIB_PROV, 0, PROV_R_UNABLE_TO_GET_PARENT_STRENGTH),
     "unable to get parent strength"},
     {ERR_PACK(ERR_LIB_PROV, 0, PROV_R_UNABLE_TO_INITIALISE_CIPHERS),
diff --git a/providers/common/provider_seeding.c b/providers/common/provider_seeding.c
new file mode 100644
index 0000000000..98704a2cdf
--- /dev/null
+++ b/providers/common/provider_seeding.c
@@ -0,0 +1,73 @@
+/*
+ * Copyright 2020 The OpenSSL Project Authors. All Rights Reserved.
+ *
+ * Licensed under the Apache License 2.0 (the "License").  You may not use
+ * this file except in compliance with the License.  You can obtain a copy
+ * in the file LICENSE in the source distribution or at
+ * https://www.openssl.org/source/license.html
+ */
+
+#include <openssl/core_dispatch.h>
+#include "prov/seeding.h"
+
+static OSSL_FUNC_get_entropy_fn *c_get_entropy = NULL;
+static OSSL_FUNC_cleanup_entropy_fn *c_cleanup_entropy = NULL;
+static OSSL_FUNC_get_nonce_fn *c_get_nonce = NULL;
+static OSSL_FUNC_cleanup_nonce_fn *c_cleanup_nonce = NULL;
+
+int ossl_prov_seeding_from_dispatch(const OSSL_DISPATCH *fns)
+{
+    for (; fns->function_id != 0; fns++) {
+        switch (fns->function_id) {
+        case OSSL_FUNC_GET_ENTROPY:
+            if (c_get_entropy == NULL)
+                c_get_entropy = OSSL_FUNC_get_entropy(fns);
+            break;
+        case OSSL_FUNC_CLEANUP_ENTROPY:
+            if (c_cleanup_entropy == NULL)
+                c_cleanup_entropy = OSSL_FUNC_cleanup_entropy(fns);
+            break;
+        case OSSL_FUNC_GET_NONCE:
+            if (c_get_nonce == NULL)
+                c_get_nonce = OSSL_FUNC_get_nonce(fns);
+            break;
+        case OSSL_FUNC_CLEANUP_NONCE:
+            if (c_cleanup_nonce == NULL)
+                c_cleanup_nonce = OSSL_FUNC_cleanup_nonce(fns);
+            break;
+        }
+    }
+    return 1;
+}
+
+size_t ossl_prov_get_entropy(PROV_CTX *prov_ctx, unsigned char **pout,
+                             int entropy, size_t min_len, size_t max_len)
+{
+    if (c_get_entropy == NULL)
+        return 0;
+    return c_get_entropy(ossl_prov_ctx_get0_handle(prov_ctx),
+                         pout, entropy, min_len, max_len);
+}
+
+void ossl_prov_cleanup_entropy(PROV_CTX *prov_ctx, unsigned char *buf,
+                               size_t len)
+{
+    if (c_cleanup_entropy != NULL)
+        c_cleanup_entropy(ossl_prov_ctx_get0_handle(prov_ctx), buf, len);
+}
+
+size_t ossl_prov_get_nonce(PROV_CTX *prov_ctx, unsigned char **pout,
+                           size_t min_len, size_t max_len,
+                           const void *salt,size_t salt_len)
+{
+    if (c_get_nonce == NULL)
+        return 0;
+    return c_get_nonce(ossl_prov_ctx_get0_handle(prov_ctx), pout,
+                       min_len, max_len, salt, salt_len);
+}
+
+void ossl_prov_cleanup_nonce(PROV_CTX *prov_ctx, unsigned char *buf, size_t len)
+{
+    if (c_cleanup_nonce != NULL)
+        c_cleanup_nonce(ossl_prov_ctx_get0_handle(prov_ctx), buf, len);
+}
diff --git a/providers/defltprov.c b/providers/defltprov.c
index b309ba798c..e5d7fe4877 100644
--- a/providers/defltprov.c
+++ b/providers/defltprov.c
@@ -19,6 +19,7 @@
 #include "prov/providercommon.h"
 #include "prov/implementations.h"
 #include "prov/provider_util.h"
+#include "prov/seeding.h"
 #include "internal/nelem.h"
 
 /*
@@ -527,7 +528,8 @@ int ossl_default_provider_init(const OSSL_CORE_HANDLE *handle,
     OSSL_FUNC_core_get_libctx_fn *c_get_libctx = NULL;
     BIO_METHOD *corebiometh;
 
-    if (!ossl_prov_bio_from_dispatch(in))
+    if (!ossl_prov_bio_from_dispatch(in)
+            || !ossl_prov_seeding_from_dispatch(in))
         return 0;
     for (; in->function_id != 0; in++) {
         switch (in->function_id) {
diff --git a/providers/fips/fipsprov.c b/providers/fips/fipsprov.c
index 33b2f0213e..ffb7510054 100644
--- a/providers/fips/fipsprov.c
+++ b/providers/fips/fipsprov.c
@@ -18,6 +18,7 @@
 #include "prov/providercommon.h"
 #include "prov/providercommonerr.h"
 #include "prov/provider_util.h"
+#include "prov/seeding.h"
 #include "self_test.h"
 
 static const char FIPS_DEFAULT_PROPERTIES[] = "provider=fips,fips=yes";
@@ -495,6 +496,8 @@ int OSSL_provider_init(const OSSL_CORE_HANDLE *handle,
     FIPS_GLOBAL *fgbl;
     OSSL_LIB_CTX *libctx = NULL;
 
+    if (!ossl_prov_seeding_from_dispatch(in))
+        return 0;
     for (; in->function_id != 0; in++) {
         switch (in->function_id) {
         case OSSL_FUNC_CORE_GET_LIBCTX:
@@ -575,10 +578,9 @@ int OSSL_provider_init(const OSSL_CORE_HANDLE *handle,
         case OSSL_FUNC_BIO_VSNPRINTF:
             c_BIO_vsnprintf = OSSL_FUNC_BIO_vsnprintf(in);
             break;
-        case OSSL_FUNC_SELF_TEST_CB: {
+        case OSSL_FUNC_SELF_TEST_CB:
             c_stcbfn = OSSL_FUNC_self_test_cb(in);
             break;
-        }
         default:
             /* Just ignore anything we don't understand */
             break;
diff --git a/providers/implementations/include/prov/seeding.h b/providers/implementations/include/prov/seeding.h
index ec69040606..448ff0366b 100644
--- a/providers/implementations/include/prov/seeding.h
+++ b/providers/implementations/include/prov/seeding.h
@@ -7,7 +7,8 @@
  * https://www.openssl.org/source/license.html
  */
 
-#include "prov/rand_pool.h"
+#include "prov/provider_ctx.h"
+#include "crypto/rand_pool.h"
 
 /* Hardware-based seeding functions. */
 size_t prov_acquire_entropy_from_tsc(RAND_POOL *pool);
@@ -18,9 +19,6 @@ size_t prov_drbg_get_additional_data(RAND_POOL *pool, unsigned char **pout);
 
 void prov_drbg_cleanup_additional_data(RAND_POOL *pool, unsigned char *out);
 
-size_t ossl_pool_acquire_entropy(RAND_POOL *pool);
-int ossl_pool_add_nonce_data(RAND_POOL *pool);
-
 /*
  * Add some platform specific additional data
  *
@@ -32,3 +30,17 @@ int ossl_pool_add_nonce_data(RAND_POOL *pool);
  */
 int rand_pool_add_additional_data(RAND_POOL *pool);
 
+/*
+ * External seeding functions from the core dispatch table.
+ */
+int ossl_prov_seeding_from_dispatch(const OSSL_DISPATCH *fns);
+
+size_t ossl_prov_get_entropy(PROV_CTX *prov_ctx, unsigned char **pout,
+                             int entropy, size_t min_len, size_t max_len);
+void ossl_prov_cleanup_entropy(PROV_CTX *prov_ctx, unsigned char *buf,
+                               size_t len);
+size_t ossl_prov_get_nonce(PROV_CTX *prov_ctx, unsigned char **pout,
+                           size_t min_len, size_t max_len,
+                           const void *salt, size_t salt_len);
+void ossl_prov_cleanup_nonce(PROV_CTX *prov_ctx, unsigned char *buf,
+                             size_t len);
diff --git a/providers/implementations/rands/build.info b/providers/implementations/rands/build.info
index 1e710bb510..2ca0cdadc7 100644
--- a/providers/implementations/rands/build.info
+++ b/providers/implementations/rands/build.info
@@ -1,6 +1,6 @@
 SUBDIRS=seeding
 
-$COMMON=drbg.c test_rng.c drbg_ctr.c drbg_hash.c drbg_hmac.c crngt.c rand_pool.c
+$COMMON=drbg.c test_rng.c drbg_ctr.c drbg_hash.c drbg_hmac.c crngt.c
 
 SOURCE[../../libfips.a]=$COMMON
 SOURCE[../../libnonfips.a]=$COMMON
diff --git a/providers/implementations/rands/crngt.c b/providers/implementations/rands/crngt.c
index 72907b5a88..f1b31df101 100644
--- a/providers/implementations/rands/crngt.c
+++ b/providers/implementations/rands/crngt.c
@@ -20,40 +20,35 @@
 #include "prov/providercommon.h"
 #include "prov/provider_ctx.h"
 #include "internal/cryptlib.h"
-#include "prov/rand_pool.h"
+#include "crypto/rand_pool.h"
 #include "drbg_local.h"
 #include "prov/seeding.h"
 
 typedef struct crng_test_global_st {
     unsigned char crngt_prev[EVP_MAX_MD_SIZE];
-    RAND_POOL *crngt_pool;
+    EVP_MD *md;
+    int preloaded;
+    CRYPTO_RWLOCK *lock;
 } CRNG_TEST_GLOBAL;
 
-static int crngt_get_entropy(OSSL_LIB_CTX *ctx, RAND_POOL *pool,
+static int crngt_get_entropy(PROV_CTX *provctx, const EVP_MD *digest,
                              unsigned char *buf, unsigned char *md,
                              unsigned int *md_size)
 {
     int r;
     size_t n;
     unsigned char *p;
-    EVP_MD *fmd;
 
-    if (pool == NULL)
-        return 0;
-
-    n = ossl_pool_acquire_entropy(pool);
-    if (n >= CRNGT_BUFSIZ) {
-        fmd = EVP_MD_fetch(ctx, "SHA256", "");
-        if (fmd == NULL)
-            return 0;
-        p = rand_pool_detach(pool);
-        r = EVP_Digest(p, CRNGT_BUFSIZ, md, md_size, fmd, NULL);
+    n = ossl_prov_get_entropy(provctx, &p, 0, CRNGT_BUFSIZ, CRNGT_BUFSIZ);
+    if (n == CRNGT_BUFSIZ) {
+        r = EVP_Digest(p, CRNGT_BUFSIZ, md, md_size, digest, NULL);
         if (r != 0)
             memcpy(buf, p, CRNGT_BUFSIZ);
-        rand_pool_reattach(pool, p);
-        EVP_MD_free(fmd);
-        return r;
+        ossl_prov_cleanup_entropy(provctx, p, n);
+        return r != 0;
     }
+    if (n != 0)
+        ossl_prov_cleanup_entropy(provctx, p, n);
     return 0;
 }
 
@@ -61,31 +56,30 @@ static void rand_crng_ossl_ctx_free(void *vcrngt_glob)
 {
     CRNG_TEST_GLOBAL *crngt_glob = vcrngt_glob;
 
-    rand_pool_free(crngt_glob->crngt_pool);
+    CRYPTO_THREAD_lock_free(crngt_glob->lock);
+    EVP_MD_free(crngt_glob->md);
     OPENSSL_free(crngt_glob);
 }
 
 static void *rand_crng_ossl_ctx_new(OSSL_LIB_CTX *ctx)
 {
-    unsigned char buf[CRNGT_BUFSIZ];
     CRNG_TEST_GLOBAL *crngt_glob = OPENSSL_zalloc(sizeof(*crngt_glob));
 
     if (crngt_glob == NULL)
         return NULL;
 
-    if ((crngt_glob->crngt_pool
-         = rand_pool_new(0, 1, CRNGT_BUFSIZ, CRNGT_BUFSIZ)) == NULL) {
+    if ((crngt_glob->md = EVP_MD_fetch(ctx, "SHA256", "")) == NULL) {
         OPENSSL_free(crngt_glob);
         return NULL;
     }
-    if (crngt_get_entropy(ctx, crngt_glob->crngt_pool, buf,
-                          crngt_glob->crngt_prev, NULL)) {
-        OPENSSL_cleanse(buf, sizeof(buf));
-        return crngt_glob;
+
+    if ((crngt_glob->lock = CRYPTO_THREAD_lock_new()) == NULL) {
+        EVP_MD_free(crngt_glob->md);
+        OPENSSL_free(crngt_glob);
+        return NULL;
     }
-    rand_pool_free(crngt_glob->crngt_pool);
-    OPENSSL_free(crngt_glob);
-    return NULL;
+
+    return crngt_glob;
 }
 
 static const OSSL_LIB_CTX_METHOD rand_crng_ossl_ctx_method = {
@@ -109,12 +103,14 @@ size_t ossl_crngt_get_entropy(PROV_DRBG *drbg,
                               int entropy, size_t min_len, size_t max_len,
                               int prediction_resistance)
 {
-    unsigned char buf[CRNGT_BUFSIZ], md[EVP_MAX_MD_SIZE];
+    unsigned char md[EVP_MAX_MD_SIZE];
+    unsigned char buf[CRNGT_BUFSIZ];
+    unsigned char *ent, *entp, *entbuf;
     unsigned int sz;
-    RAND_POOL *pool;
-    size_t q, r = 0, s, t = 0;
-    int attempts = 3, crng_test_pass = 1;
-    OSSL_LIB_CTX *libctx = PROV_LIBCTX_OF(drbg->provctx);
+    size_t bytes_needed;
+    size_t r = 0, s, t;
+    int crng_test_pass = 1;
+    OSSL_LIB_CTX *libctx = ossl_prov_ctx_get0_libctx(drbg->provctx);
     CRNG_TEST_GLOBAL *crngt_glob
         = ossl_lib_ctx_get_data(libctx, OSSL_LIB_CTX_RAND_CRNGT_INDEX,
                                 &rand_crng_ossl_ctx_method);
@@ -125,9 +121,32 @@ size_t ossl_crngt_get_entropy(PROV_DRBG *drbg,
     if (crngt_glob == NULL)
         return 0;
 
-    if ((pool = rand_pool_new(entropy, 1, min_len, max_len)) == NULL)
+    if (!CRYPTO_THREAD_write_lock(crngt_glob->lock))
         return 0;
 
+    if (!crngt_glob->preloaded) {
+        if (!crngt_get_entropy(drbg->provctx, crngt_glob->md, buf,
+                               crngt_glob->crngt_prev, NULL)) {
+            OPENSSL_cleanse(buf, sizeof(buf));
+            goto unlock_return;
+        }
+        crngt_glob->preloaded = 1;
+    }
+
+    /*
+     * Calculate how many bytes of seed material we require, rounded up
+     * to the nearest byte.  If the entropy is of less than full quality,
+     * the amount required should be scaled up appropriately here.
+     */
+    bytes_needed = (entropy + 7) / 8;
+    if (bytes_needed < min_len)
+        bytes_needed = min_len;
+    if (bytes_needed > max_len)
+        goto unlock_return;
+    entp = ent = OPENSSL_secure_malloc(bytes_needed);
+    if (ent == NULL)
+        goto unlock_return;
+
     OSSL_SELF_TEST_get_callback(libctx, &stcb, &stcbarg);
     if (stcb != NULL) {
         st = OSSL_SELF_TEST_new(stcb, stcbarg);
@@ -137,10 +156,14 @@ size_t ossl_crngt_get_entropy(PROV_DRBG *drbg,
                                OSSL_SELF_TEST_DESC_RNG);
     }
 
-    while ((q = rand_pool_bytes_needed(pool, 1)) > 0 && attempts-- > 0) {
-        s = q > sizeof(buf) ? sizeof(buf) : q;
-        if (!crngt_get_entropy(libctx, crngt_glob->crngt_pool, buf, md, &sz))
+    for (t = bytes_needed; t > 0;) {
+        /* Care needs to be taken to avoid overrunning the buffer */
+        s = t >= CRNGT_BUFSIZ ? CRNGT_BUFSIZ : t;
+        entbuf = t >= CRNGT_BUFSIZ ? entp : buf;
+        if (!crngt_get_entropy(drbg->provctx, crngt_glob->md, entbuf, md, &sz))
             goto err;
+        if (t < CRNGT_BUFSIZ)
+            memcpy(entp, buf, t);
         /* Force a failure here if the callback returns 1 */
         if (OSSL_SELF_TEST_oncorrupt_byte(st, md))
             memcpy(md, crngt_glob->crngt_prev, sz);
@@ -148,23 +171,26 @@ size_t ossl_crngt_get_entropy(PROV_DRBG *drbg,
             crng_test_pass = 0;
             goto err;
         }
-        if (!rand_pool_add(pool, buf, s, s * 8))
-            goto err;
+        /* Update for next block */
         memcpy(crngt_glob->crngt_prev, md, sz);
-        t += s;
-        attempts++;
+        entp += s;
+        t -= s;
     }
-    r = t;
-    *pout = rand_pool_detach(pool);
-err:
+    r = bytes_needed;
+    *pout = ent;
+    ent = NULL;
+
+ err:
     OSSL_SELF_TEST_onend(st, crng_test_pass);
     OSSL_SELF_TEST_free(st);
-    OPENSSL_cleanse(buf, sizeof(buf));
-    rand_pool_free(pool);
+    OPENSSL_secure_clear_free(ent, bytes_needed);
+
+ unlock_return:
+    CRYPTO_THREAD_unlock(crngt_glob->lock);
     return r;
 }
 
-void ossl_crngt_cleanup_entropy(PROV_DRBG *drbg,
+void ossl_crngt_cleanup_entropy(ossl_unused PROV_DRBG *drbg,
                                 unsigned char *out, size_t outlen)
 {
     OPENSSL_secure_clear_free(out, outlen);
diff --git a/providers/implementations/rands/drbg.c b/providers/implementations/rands/drbg.c
index a294ed7f1d..cc965c9bc0 100644
--- a/providers/implementations/rands/drbg.c
+++ b/providers/implementations/rands/drbg.c
@@ -17,7 +17,7 @@
 #include "internal/thread_once.h"
 #include "crypto/cryptlib.h"
 #include "prov/seeding.h"
-#include "prov/rand_pool.h"
+#include "crypto/rand_pool.h"
 #include "prov/provider_ctx.h"
 #include "prov/providercommonerr.h"
 #include "prov/providercommon.h"
@@ -110,18 +110,15 @@ static unsigned int get_parent_reseed_count(PROV_DRBG *drbg)
 {
     OSSL_PARAM params[2] = { OSSL_PARAM_END, OSSL_PARAM_END };
     void *parent = drbg->parent;
-    unsigned int r;
+    unsigned int r = 0;
 
     *params = OSSL_PARAM_construct_uint(OSSL_DRBG_PARAM_RESEED_COUNTER, &r);
     if (!ossl_drbg_lock_parent(drbg)) {
         ERR_raise(ERR_LIB_PROV, PROV_R_UNABLE_TO_LOCK_PARENT);
         goto err;
     }
-    if (!drbg->parent_get_ctx_params(parent, params)) {
-        ossl_drbg_unlock_parent(drbg);
-        ERR_raise(ERR_LIB_PROV, PROV_R_UNABLE_TO_GET_RESEED_PROP_CTR);
-        goto err;
-    }
+    if (!drbg->parent_get_ctx_params(parent, params))
+        r = 0;
     ossl_drbg_unlock_parent(drbg);
     return r;
 
@@ -148,106 +145,90 @@ static size_t prov_drbg_get_entropy(PROV_DRBG *drbg, unsigned char **pout,
                                     int entropy, size_t min_len,
                                     size_t max_len, int prediction_resistance)
 {
-    size_t ret = 0;
-    size_t entropy_available = 0;
-    RAND_POOL *pool;
     unsigned int p_str;
+    size_t r, bytes_needed;
+    unsigned char *buffer;
 
-    if (drbg->parent != NULL) {
-        if (!get_parent_strength(drbg, &p_str))
-            return 0;
-        if (drbg->strength > p_str) {
-            /*
-             * We currently don't support the algorithm from NIST SP 800-90C
-             * 10.1.2 to use a weaker DRBG as source
-             */
-            ERR_raise(ERR_LIB_RAND, PROV_R_PARENT_STRENGTH_TOO_WEAK);
-            return 0;
-        }
+    if (!get_parent_strength(drbg, &p_str))
+        return 0;
+    if (drbg->strength > p_str) {
+        /*
+         * We currently don't support the algorithm from NIST SP 800-90C
+         * 10.1.2 to use a weaker DRBG as source
+         */
+        ERR_raise(ERR_LIB_PROV, PROV_R_PARENT_STRENGTH_TOO_WEAK);
+        return 0;
     }
 
-    if (drbg->seed_pool != NULL) {
-        pool = drbg->seed_pool;
-        pool->entropy_requested = entropy;
-    } else {
-        pool = rand_pool_new(entropy, 1, min_len, max_len);
-        if (pool == NULL) {
-            ERR_raise(ERR_LIB_PROV, ERR_R_MALLOC_FAILURE);
-            return 0;
-        }
+    if (drbg->parent_generate == NULL) {
+        ERR_raise(ERR_LIB_PROV, PROV_R_PARENT_CANNOT_GENERATE_RANDOM_NUMBERS);
+        return 0;
     }
 
-    if (drbg->parent != NULL) {
-        size_t bytes_needed = rand_pool_bytes_needed(pool, 1 /*entropy_factor*/);
-        unsigned char *buffer = rand_pool_add_begin(pool, bytes_needed);
+    /* Figure out how many bytes we need */
+    bytes_needed = entropy >= 0 ? (entropy + 7) / 8 : 0;
+    if (bytes_needed < min_len)
+        bytes_needed = min_len;
+    if (bytes_needed > max_len)
+        bytes_needed = max_len;
 
-        if (buffer != NULL) {
-            size_t bytes = 0;
-
-            if (drbg->parent_generate == NULL)
-                goto err;
-            /*
-             * Our lock is already held, but we need to lock our parent before
-             * generating bits from it. (Note: taking the lock will be a no-op
-             * if locking if drbg->parent->lock == NULL.)
-             */
-            ossl_drbg_lock_parent(drbg);
-            /*
-             * Get random data from parent.  Include our DRBG address as
-             * additional input, in order to provide a distinction between
-             * different DRBG child instances.
-             *
-             * Note: using the sizeof() operator on a pointer triggers
-             *       a warning in some static code analyzers, but it's
-             *       intentional and correct here.
-             */
-            if (drbg->parent_generate(drbg->parent, buffer, bytes_needed,
-                                      drbg->strength, prediction_resistance,
-                                      (unsigned char *)&drbg,
-                                      sizeof(drbg)) != 0)
-                bytes = bytes_needed;
-            ossl_drbg_unlock_parent(drbg);
-            drbg->parent_reseed_counter = get_parent_reseed_count(drbg);
-
-            rand_pool_add_end(pool, bytes, 8 * bytes);
-            entropy_available = rand_pool_entropy_available(pool);
-        }
-    } else {
-        /* Get entropy by polling system entropy sources. */
-        entropy_available = ossl_pool_acquire_entropy(pool);
+    /* Allocate storage */
+    buffer = OPENSSL_secure_malloc(bytes_needed);
+    if (buffer == NULL) {
+        ERR_raise(ERR_LIB_PROV, ERR_R_MALLOC_FAILURE);
+        return 0;
     }
 
-    if (entropy_available > 0) {
-        ret   = rand_pool_length(pool);
-        *pout = rand_pool_detach(pool);
+    /*
+     * Our lock is already held, but we need to lock our parent before
+     * generating bits from it.  Note: taking the lock will be a no-op
+     * if locking is not required (while drbg->parent->lock == NULL).
+     */
+    ossl_drbg_lock_parent(drbg);
+    /*
+     * Get random data from parent.  Include our DRBG address as
+     * additional input, in order to provide a distinction between
+     * different DRBG child instances.
+     *
+     * Note: using the sizeof() operator on a pointer triggers
+     *       a warning in some static code analyzers, but it's
+     *       intentional and correct here.
+     */
+    r = drbg->parent_generate(drbg->parent, buffer, bytes_needed,
+                              drbg->strength, prediction_resistance,
+                              (unsigned char *)&drbg,
+                              sizeof(drbg));
+    ossl_drbg_unlock_parent(drbg);
+    if (r == 0) {
+        OPENSSL_secure_clear_free(buffer, bytes_needed);
+        ERR_raise(ERR_LIB_PROV, PROV_R_GENERATE_ERROR);
+        return 0;
     }
-
-err:
-    if (drbg->seed_pool == NULL)
-        rand_pool_free(pool);
-    return ret;
+    *pout = buffer;
+    return bytes_needed;
 }
 
 /*
  * Implements the cleanup_entropy() callback
  *
  */
-static void prov_drbg_cleanup_entropy(PROV_DRBG *drbg,
+static void prov_drbg_cleanup_entropy(ossl_unused PROV_DRBG *drbg,
                                       unsigned char *out, size_t outlen)
 {
-    if (drbg->seed_pool == NULL) {
-        OPENSSL_secure_clear_free(out, outlen);
-    }
+    OPENSSL_secure_clear_free(out, outlen);
 }
 
 static size_t get_entropy(PROV_DRBG *drbg, unsigned char **pout, int entropy,
                           size_t min_len, size_t max_len,
                           int prediction_resistance)
 {
-#ifdef FIPS_MODULE
     if (drbg->parent == NULL)
+#ifdef FIPS_MODULE
         return ossl_crngt_get_entropy(drbg, pout, entropy, min_len, max_len,
                                       prediction_resistance);
+#else
+        return ossl_prov_get_entropy(drbg->provctx, pout, entropy, min_len,
+                                     max_len);
 #endif
 
     return prov_drbg_get_entropy(drbg, pout, entropy, min_len, max_len,
@@ -256,12 +237,15 @@ static size_t get_entropy(PROV_DRBG *drbg, unsigned char **pout, int entropy,
 
 static void cleanup_entropy(PROV_DRBG *drbg, unsigned char *out, size_t outlen)
 {
+    if (drbg->parent == NULL) {
 #ifdef FIPS_MODULE
-    if (drbg->parent == NULL)
         ossl_crngt_cleanup_entropy(drbg, out, outlen);
-    else
+#else
+        ossl_prov_cleanup_entropy(drbg->provctx, out, outlen);
 #endif
+    } else {
         prov_drbg_cleanup_entropy(drbg, out, outlen);
+    }
 }
 
 #ifndef PROV_RAND_GET_RANDOM_NONCE
@@ -311,75 +295,45 @@ static const OSSL_LIB_CTX_METHOD drbg_nonce_ossl_ctx_method = {
 };
 
 /* Get a nonce from the operating system */
-static size_t prov_drbg_get_nonce(PROV_DRBG *drbg,
-                                  unsigned char **pout,
-                                  int entropy, size_t min_len, size_t max_len)
+static size_t prov_drbg_get_nonce(PROV_DRBG *drbg, unsigned char **pout,
+                                  size_t min_len, size_t max_len)
 {
     size_t ret = 0, n;
-    RAND_POOL *pool;
     unsigned char *buf = NULL;
-    OSSL_LIB_CTX *libctx = PROV_LIBCTX_OF(drbg->provctx);
+    OSSL_LIB_CTX *libctx = ossl_prov_ctx_get0_libctx(drbg->provctx);
     PROV_DRBG_NONCE_GLOBAL *dngbl
         = ossl_lib_ctx_get_data(libctx, OSSL_LIB_CTX_DRBG_NONCE_INDEX,
                                 &drbg_nonce_ossl_ctx_method);
     struct {
-        void *instance;
+        void *drbg;
         int count;
     } data;
-    
+
     if (dngbl == NULL)
         return 0;
 
-    if (drbg->parent != NULL) {
-        if (drbg->parent_nonce != NULL) {
-            n = drbg->parent_nonce(drbg->parent, NULL, 0, drbg->min_noncelen,
-                                   drbg->max_noncelen);
-            if (n > 0 && (buf = OPENSSL_malloc(n)) != NULL) {
-                ret = drbg->parent_nonce(drbg->parent, buf, 0,
-                                         drbg->min_noncelen,
-                                         drbg->max_noncelen);
-                if (ret == n) {
-                    *pout = buf;
-                    return ret;
-                }
-                OPENSSL_free(buf);
+    if (drbg->parent != NULL && drbg->parent_nonce != NULL) {
+        n = drbg->parent_nonce(drbg->parent, NULL, 0, drbg->min_noncelen,
+                               drbg->max_noncelen);
+        if (n > 0 && (buf = OPENSSL_malloc(n)) != NULL) {
+            ret = drbg->parent_nonce(drbg->parent, buf, 0,
+                                     drbg->min_noncelen, drbg->max_noncelen);
+            if (ret == n) {
+                *pout = buf;
+                return ret;
             }
+            OPENSSL_free(buf);
         }
     }
 
-    /* Use the built in nonce source */
+    /* Use the built in nonce source plus some of our specifics */
     memset(&data, 0, sizeof(data));
-    pool = rand_pool_new(0, 0, min_len, max_len);
-    if (pool == NULL)
-        return 0;
-
-    if (ossl_pool_add_nonce_data(pool) == 0)
-        goto err;
-
-    data.instance = drbg;
+    data.drbg = drbg;
     CRYPTO_atomic_add(&dngbl->rand_nonce_count, 1, &data.count,
                       dngbl->rand_nonce_lock);
-
-    if (rand_pool_add(pool, (unsigned char *)&data, sizeof(data), 0) == 0)
-        goto err;
-
-    ret   = rand_pool_length(pool);
-    *pout = rand_pool_detach(pool);
-
- err:
-    rand_pool_free(pool);
-
-    return ret;
+    return ossl_prov_get_nonce(drbg->provctx, pout, min_len, max_len,
+                               &data, sizeof(data));
 }
-
-static void prov_drbg_clear_nonce(PROV_DRBG *drbg, unsigned char *nonce,
-                                  size_t noncelen)
-{
-    OPENSSL_clear_free(nonce, noncelen);
-}
-#else
-# define prov_drbg_clear_nonce(drbg, nonce, len) \
-    OPENSSL_clear_free((nonce), (len))
 #endif /* PROV_RAND_GET_RANDOM_NONCE */
 
 /*
@@ -465,8 +419,7 @@ int ossl_prov_drbg_instantiate(PROV_DRBG *drbg, unsigned int strength,
         }
 #ifndef PROV_RAND_GET_RANDOM_NONCE
         else { /* parent == NULL */
-            noncelen = prov_drbg_get_nonce(drbg, &nonce, drbg->strength / 2,
-                                           drbg->min_noncelen, 
+            noncelen = prov_drbg_get_nonce(drbg, &nonce, drbg->min_noncelen, 
                                            drbg->max_noncelen);
             if (noncelen < drbg->min_noncelen
                     || noncelen > drbg->max_noncelen) {
@@ -507,7 +460,8 @@ int ossl_prov_drbg_instantiate(PROV_DRBG *drbg, unsigned int strength,
  end:
     if (entropy != NULL)
         cleanup_entropy(drbg, entropy, entropylen);
-    prov_drbg_clear_nonce(drbg, nonce, noncelen);
+    if (nonce != NULL)
+        ossl_prov_cleanup_nonce(drbg->provctx, nonce, noncelen);
     if (drbg->state == EVP_RAND_STATE_READY)
         return 1;
     return 0;
@@ -745,14 +699,6 @@ int ossl_prov_drbg_generate(PROV_DRBG *drbg, unsigned char *out, size_t outlen,
  */
 static int rand_drbg_restart(PROV_DRBG *drbg)
 {
-    if (drbg->seed_pool != NULL) {
-        drbg->state = EVP_RAND_STATE_ERROR;
-        rand_pool_free(drbg->seed_pool);
-        drbg->seed_pool = NULL;
-        ERR_raise(ERR_LIB_RAND, ERR_R_INTERNAL_ERROR);
-        return 0;
-    }
-
     /* repair error state */
     if (drbg->state == EVP_RAND_STATE_ERROR)
         drbg->uninstantiate(drbg);
@@ -762,8 +708,6 @@ static int rand_drbg_restart(PROV_DRBG *drbg)
         /* reinstantiate drbg */
         ossl_prov_drbg_instantiate(drbg, drb