Add selftest callback to CRNG output test

Reviewed-by: Matt Caswell <matt@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/12795)

5 files changed, 46 insertions, 11 deletions

diff --git a/crypto/self_test_core.c b/crypto/self_test_core.c
index 1a6f828c1d..ca8925abe5 100644
--- a/crypto/self_test_core.c
+++ b/crypto/self_test_core.c
@@ -157,12 +157,15 @@ void OSSL_SELF_TEST_onend(OSSL_SELF_TEST *st, int ret)
  * is modified (corrupted). This is used to modify output signatures or
  * ciphertext before they are verified or decrypted.
  */
-void OSSL_SELF_TEST_oncorrupt_byte(OSSL_SELF_TEST *st, unsigned char *bytes)
+int OSSL_SELF_TEST_oncorrupt_byte(OSSL_SELF_TEST *st, unsigned char *bytes)
 {
     if (st != NULL && st->cb != NULL) {
         st->phase = OSSL_SELF_TEST_PHASE_CORRUPT;
         self_test_setparams(st);
-        if (!st->cb(st->params, st->cb_arg))
+        if (!st->cb(st->params, st->cb_arg)) {
             bytes[0] ^= 1;
+            return 1;
+        }
     }
+    return 0;
 }
diff --git a/doc/man3/OSSL_SELF_TEST_new.pod b/doc/man3/OSSL_SELF_TEST_new.pod
index b2c4f5ccce..744c82e204 100644
--- a/doc/man3/OSSL_SELF_TEST_new.pod
+++ b/doc/man3/OSSL_SELF_TEST_new.pod
@@ -17,7 +17,7 @@ OSSL_SELF_TEST_onend - functionality to trigger a callback during a self test
 
  void OSSL_SELF_TEST_onbegin(OSSL_SELF_TEST *st, const char *type,
                              const char *desc);
- void OSSL_SELF_TEST_oncorrupt_byte(OSSL_SELF_TEST *st, unsigned char *bytes);
+ int OSSL_SELF_TEST_oncorrupt_byte(OSSL_SELF_TEST *st, unsigned char *bytes);
  void OSSL_SELF_TEST_onend(OSSL_SELF_TEST *st, int ret);
 
 =head1 DESCRIPTION
@@ -104,6 +104,9 @@ This allows the callback to identify the sub category of the test being run.
 OSSL_SELF_TEST_new() returns the allocated B<OSSL_SELF_TEST> object, or NULL if
 it fails.
 
+OSSL_SELF_TEST_oncorrupt_byte() returns 1 if corruption occurs, otherwise it
+returns 0.
+
 =head1 EXAMPLES
 
 A single self test could be set up in the following way:
diff --git a/doc/man7/OSSL_PROVIDER-FIPS.pod b/doc/man7/OSSL_PROVIDER-FIPS.pod
index 2ae999e023..98c6079d72 100644
--- a/doc/man7/OSSL_PROVIDER-FIPS.pod
+++ b/doc/man7/OSSL_PROVIDER-FIPS.pod
@@ -212,6 +212,10 @@ Known answer test for a Deterministic Random Bit Generator.
 
 Conditional test that is run during the generation of key pairs.
 
+=item "Continuous_RNG_Test" (B<OSSL_SELF_TEST_TYPE_CRNG>)
+
+Continuous random number generator test.
+
 =back
 
 The "Module_Integrity" self test is always run at startup.
@@ -289,6 +293,10 @@ Key Derivation Function tests used with the "KAT_KDF" type.
 
 DRBG tests used with the "DRBG" type.
 
+= item "RNG" (B<OSSL_SELF_TEST_DESC_RNG>)
+
+"Continuous_RNG_Test" uses this.
+
 =back
 
 =head1 EXAMPLES
diff --git a/include/openssl/self_test.h b/include/openssl/self_test.h
index 4d99aaa4e3..be375c9469 100644
--- a/include/openssl/self_test.h
+++ b/include/openssl/self_test.h
@@ -60,6 +60,7 @@ extern "C" {
 # define OSSL_SELF_TEST_DESC_KA_ECDH        "ECDH"
 # define OSSL_SELF_TEST_DESC_KDF_HKDF       "HKDF"
 # define OSSL_SELF_TEST_DESC_KDF_SSKDF      "SSKDF"
+# define OSSL_SELF_TEST_DESC_RNG            "RNG"
 
 # ifdef __cplusplus
 }
@@ -75,7 +76,7 @@ void OSSL_SELF_TEST_free(OSSL_SELF_TEST *st);
 
 void OSSL_SELF_TEST_onbegin(OSSL_SELF_TEST *st, const char *type,
                             const char *desc);
-void OSSL_SELF_TEST_oncorrupt_byte(OSSL_SELF_TEST *st, unsigned char *bytes);
+int OSSL_SELF_TEST_oncorrupt_byte(OSSL_SELF_TEST *st, unsigned char *bytes);
 void OSSL_SELF_TEST_onend(OSSL_SELF_TEST *st, int ret);
 
 #endif /* OPENSSL_SELF_TEST_H */
diff --git a/providers/implementations/rands/crngt.c b/providers/implementations/rands/crngt.c
index e23485291b..c6874f8916 100644
--- a/providers/implementations/rands/crngt.c
+++ b/providers/implementations/rands/crngt.c
@@ -94,8 +94,8 @@ static const OPENSSL_CTX_METHOD rand_crng_ossl_ctx_method = {
 };
 
 static int prov_crngt_compare_previous(const unsigned char *prev,
-                                        const unsigned char *cur,
-                                        size_t sz)
+                                       const unsigned char *cur,
+                                       size_t sz)
 {
     const int res = memcmp(prev, cur, sz) != 0;
 
@@ -113,11 +113,14 @@ size_t prov_crngt_get_entropy(PROV_DRBG *drbg,
     unsigned int sz;
     RAND_POOL *pool;
     size_t q, r = 0, s, t = 0;
-    int attempts = 3;
+    int attempts = 3, crng_test_pass = 1;
     OPENSSL_CTX *libctx = PROV_LIBRARY_CONTEXT_OF(drbg->provctx);
     CRNG_TEST_GLOBAL *crngt_glob
         = openssl_ctx_get_data(libctx, OPENSSL_CTX_RAND_CRNGT_INDEX,
                                &rand_crng_ossl_ctx_method);
+    OSSL_CALLBACK *stcb = NULL;
+    void *stcbarg = NULL;
+    OSSL_SELF_TEST *st = NULL;
 
     if (crngt_glob == NULL)
         return 0;
@@ -125,12 +128,27 @@ size_t prov_crngt_get_entropy(PROV_DRBG *drbg,
     if ((pool = rand_pool_new(entropy, 1, min_len, max_len)) == NULL)
         return 0;
 
+    OSSL_SELF_TEST_get_callback(libctx, &stcb, &stcbarg);
+    if (stcb != NULL) {
+        st = OSSL_SELF_TEST_new(stcb, stcbarg);
+        if (st == NULL)
+            goto err;
+        OSSL_SELF_TEST_onbegin(st, OSSL_SELF_TEST_TYPE_CRNG,
+                               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)
-            || !prov_crngt_compare_previous(crngt_glob->crngt_prev, md, sz)
-            || !rand_pool_add(pool, buf, s, s * 8))
+        if (!crngt_get_entropy(libctx, crngt_glob->crngt_pool, buf, md, &sz))
+            goto err;
+        /* Force a failure here if the callback returns 1 */
+        if (OSSL_SELF_TEST_oncorrupt_byte(st, md))
+            memcpy(md, crngt_glob->crngt_prev, sz);
+        if (!prov_crngt_compare_previous(crngt_glob->crngt_prev, md, sz)) {
+            crng_test_pass = 0;
+            goto err;
+        }
+        if (!rand_pool_add(pool, buf, s, s * 8))
             goto err;
         memcpy(crngt_glob->crngt_prev, md, sz);
         t += s;
@@ -139,6 +157,8 @@ size_t prov_crngt_get_entropy(PROV_DRBG *drbg,
     r = t;
     *pout = rand_pool_detach(pool);
 err:
+    OSSL_SELF_TEST_onend(st, crng_test_pass);
+    OSSL_SELF_TEST_free(st);
     OPENSSL_cleanse(buf, sizeof(buf));
     rand_pool_free(pool);
     return r;