Make BIGNUM rand functions available within the FIPS module

The BIGNUM rand functions were previously disabled for the FIPS module.
We can now re-enable them.

Reviewed-by: Matthias St. Pierre <Matthias.St.Pierre@ncp-e.com>
(Merged from https://github.com/openssl/openssl/pull/9193)

5 files changed, 78 insertions, 53 deletions

diff --git a/crypto/bn/bn_ctx.c b/crypto/bn/bn_ctx.c
index 476211411a..cc3c3034a4 100644
--- a/crypto/bn/bn_ctx.c
+++ b/crypto/bn/bn_ctx.c
@@ -247,6 +247,8 @@ BIGNUM *BN_CTX_get(BN_CTX *ctx)
 
 OPENSSL_CTX *bn_get_lib_ctx(BN_CTX *ctx)
 {
+    if (ctx == NULL)
+        return NULL;
     return ctx->libctx;
 }
 
diff --git a/crypto/bn/bn_rand.c b/crypto/bn/bn_rand.c
index 6967627732..a71e7d49d1 100644
--- a/crypto/bn/bn_rand.c
+++ b/crypto/bn/bn_rand.c
@@ -10,9 +10,9 @@
 #include <stdio.h>
 #include <time.h>
 #include "internal/cryptlib.h"
+#include "internal/rand_int.h"
 #include "bn_lcl.h"
 #include <openssl/rand.h>
-#include <openssl/rand_drbg.h>
 #include <openssl/sha.h>
 #include <openssl/evp.h>
 
@@ -20,10 +20,12 @@ typedef enum bnrand_flag_e {
     NORMAL, TESTING, PRIVATE
 } BNRAND_FLAG;
 
-static int bnrand(BNRAND_FLAG flag, BIGNUM *rnd, int bits, int top, int bottom)
+static int bnrand(BNRAND_FLAG flag, BIGNUM *rnd, int bits, int top, int bottom,
+                  BN_CTX *ctx)
 {
     unsigned char *buf = NULL;
     int b, ret = 0, bit, bytes, mask;
+    OPENSSL_CTX *libctx = bn_get_lib_ctx(ctx);
 
     if (bits == 0) {
         if (top != BN_RAND_TOP_ANY || bottom != BN_RAND_BOTTOM_ANY)
@@ -45,16 +47,8 @@ static int bnrand(BNRAND_FLAG flag, BIGNUM *rnd, int bits, int top, int bottom)
     }
 
     /* make a random number and set the top and bottom bits */
-    /*
-     * TODO(3.0): Temporarily disable RAND code in the FIPS module until we
-     * have made it available there.
-     */
-#if defined(FIPS_MODE)
-    BNerr(BN_F_BNRAND, ERR_R_INTERNAL_ERROR);
-    goto err;
-#else
-    b = flag == NORMAL ? RAND_bytes(buf, bytes) : RAND_priv_bytes(buf, bytes);
-#endif
+    b = flag == NORMAL ? rand_bytes_ex(libctx, buf, bytes)
+                       : rand_priv_bytes_ex(libctx, buf, bytes);
     if (b <= 0)
         goto err;
 
@@ -66,14 +60,8 @@ static int bnrand(BNRAND_FLAG flag, BIGNUM *rnd, int bits, int top, int bottom)
         unsigned char c;
 
         for (i = 0; i < bytes; i++) {
-    /*
-     * TODO(3.0): Temporarily disable RAND code in the FIPS module until we
-     * have made it available there.
-     */
-#if !defined(FIPS_MODE)
-            if (RAND_bytes(&c, 1) <= 0)
+            if (rand_bytes_ex(libctx, &c, 1) <= 0)
                 goto err;
-#endif
             if (c >= 128 && i > 0)
                 buf[i] = buf[i - 1];
             else if (c < 42)
@@ -111,23 +99,33 @@ toosmall:
     return 0;
 }
 
+int BN_rand_ex(BIGNUM *rnd, int bits, int top, int bottom, BN_CTX *ctx)
+{
+    return bnrand(NORMAL, rnd, bits, top, bottom, ctx);
+}
 int BN_rand(BIGNUM *rnd, int bits, int top, int bottom)
 {
-    return bnrand(NORMAL, rnd, bits, top, bottom);
+    return bnrand(NORMAL, rnd, bits, top, bottom, NULL);
 }
 
 int BN_bntest_rand(BIGNUM *rnd, int bits, int top, int bottom)
 {
-    return bnrand(TESTING, rnd, bits, top, bottom);
+    return bnrand(TESTING, rnd, bits, top, bottom, NULL);
+}
+
+int BN_priv_rand_ex(BIGNUM *rnd, int bits, int top, int bottom, BN_CTX *ctx)
+{
+    return bnrand(PRIVATE, rnd, bits, top, bottom, ctx);
 }
 
 int BN_priv_rand(BIGNUM *rnd, int bits, int top, int bottom)
 {
-    return bnrand(PRIVATE, rnd, bits, top, bottom);
+    return bnrand(PRIVATE, rnd, bits, top, bottom, NULL);
 }
 
 /* random number r:  0 <= r < range */
-static int bnrand_range(BNRAND_FLAG flag, BIGNUM *r, const BIGNUM *range)
+static int bnrand_range(BNRAND_FLAG flag, BIGNUM *r, const BIGNUM *range,
+                        BN_CTX *ctx)
 {
     int n;
     int count = 100;
@@ -149,7 +147,8 @@ static int bnrand_range(BNRAND_FLAG flag, BIGNUM *r, const BIGNUM *range)
          * than range
          */
         do {
-            if (!bnrand(flag, r, n + 1, BN_RAND_TOP_ANY, BN_RAND_BOTTOM_ANY))
+            if (!bnrand(flag, r, n + 1, BN_RAND_TOP_ANY, BN_RAND_BOTTOM_ANY,
+                        ctx))
                 return 0;
 
             /*
@@ -176,7 +175,7 @@ static int bnrand_range(BNRAND_FLAG flag, BIGNUM *r, const BIGNUM *range)
     } else {
         do {
             /* range = 11..._2  or  range = 101..._2 */
-            if (!bnrand(flag, r, n, BN_RAND_TOP_ANY, BN_RAND_BOTTOM_ANY))
+            if (!bnrand(flag, r, n, BN_RAND_TOP_ANY, BN_RAND_BOTTOM_ANY, ctx))
                 return 0;
 
             if (!--count) {
@@ -191,14 +190,24 @@ static int bnrand_range(BNRAND_FLAG flag, BIGNUM *r, const BIGNUM *range)
     return 1;
 }
 
+int BN_rand_range_ex(BIGNUM *r, const BIGNUM *range, BN_CTX *ctx)
+{
+    return bnrand_range(NORMAL, r, range, ctx);
+}
+
 int BN_rand_range(BIGNUM *r, const BIGNUM *range)
 {
-    return bnrand_range(NORMAL, r, range);
+    return bnrand_range(NORMAL, r, range, NULL);
+}
+
+int BN_priv_rand_range_ex(BIGNUM *r, const BIGNUM *range, BN_CTX *ctx)
+{
+    return bnrand_range(PRIVATE, r, range, ctx);
 }
 
 int BN_priv_rand_range(BIGNUM *r, const BIGNUM *range)
 {
-    return bnrand_range(PRIVATE, r, range);
+    return bnrand_range(PRIVATE, r, range, NULL);
 }
 
 int BN_pseudo_rand(BIGNUM *rnd, int bits, int top, int bottom)
@@ -237,18 +246,9 @@ int BN_generate_dsa_nonce(BIGNUM *out, const BIGNUM *range,
     unsigned char *k_bytes = NULL;
     int ret = 0;
     EVP_MD *md = NULL;
-    OPENSSL_CTX *libctx = (ctx != NULL) ? bn_get_lib_ctx(ctx) : NULL;
-    /*
-     * TODO(3.0): Temporarily disable RAND code in the FIPS module until we
-     * have made it available there.
-     */
-#ifdef FIPS_MODE
-    RAND_DRBG *privdrbg = NULL;
-#else
-    RAND_DRBG *privdrbg = OPENSSL_CTX_get0_private_drbg(libctx);
-#endif
+    OPENSSL_CTX *libctx = bn_get_lib_ctx(ctx);
 
-    if (mdctx == NULL || privdrbg == NULL)
+    if (mdctx == NULL)
         goto err;
 
     k_bytes = OPENSSL_malloc(num_k_bytes);
@@ -275,14 +275,8 @@ int BN_generate_dsa_nonce(BIGNUM *out, const BIGNUM *range,
         goto err;
     }
     for (done = 0; done < num_k_bytes;) {
-        /*
-         * TODO(3.0): Temporarily disable RAND code in the FIPS module until we
-         * have made it available there.
-         */
-#if !defined(FIPS_MODE)
-        if (!RAND_DRBG_bytes(privdrbg, random_bytes, sizeof(random_bytes)))
+        if (!rand_priv_bytes_ex(libctx, random_bytes, sizeof(random_bytes)))
             goto err;
-#endif
 
         if (!EVP_DigestInit_ex(mdctx, md, NULL)
                 || !EVP_DigestUpdate(mdctx, &done, sizeof(done))
diff --git a/doc/man3/BN_rand.pod b/doc/man3/BN_rand.pod
index 93e8c3f9d4..fc41322f8e 100644
--- a/doc/man3/BN_rand.pod
+++ b/doc/man3/BN_rand.pod
@@ -2,30 +2,37 @@
 
 =head1 NAME
 
-BN_rand, BN_priv_rand, BN_pseudo_rand,
-BN_rand_range, BN_priv_rand_range, BN_pseudo_rand_range
+BN_rand_ex, BN_rand, BN_priv_rand_ex, BN_priv_rand, BN_pseudo_rand,
+BN_rand_range_ex, BN_rand_range, BN_priv_rand_range_ex, BN_priv_rand_range,
+BN_pseudo_rand_range
 - generate pseudo-random number
 
 =head1 SYNOPSIS
 
  #include <openssl/bn.h>
 
+ int BN_rand_ex(BIGNUM *rnd, int bits, int top, int bottom, BN_CTX *ctx);
  int BN_rand(BIGNUM *rnd, int bits, int top, int bottom);
 
+ int BN_priv_rand_ex(BIGNUM *rnd, int bits, int top, int bottom, BN_CTX *ctx);
  int BN_priv_rand(BIGNUM *rnd, int bits, int top, int bottom);
 
  int BN_pseudo_rand(BIGNUM *rnd, int bits, int top, int bottom);
 
+ int BN_rand_range_ex(BIGNUM *rnd, BIGNUM *range, BN_CTX *ctx);
  int BN_rand_range(BIGNUM *rnd, BIGNUM *range);
 
+ int BN_priv_rand_range_ex(BIGNUM *rnd, BIGNUM *range, BN_CTX *ctx);
  int BN_priv_rand_range(BIGNUM *rnd, BIGNUM *range);
 
  int BN_pseudo_rand_range(BIGNUM *rnd, BIGNUM *range);
 
 =head1 DESCRIPTION
 
-BN_rand() generates a cryptographically strong pseudo-random number of
-B<bits> in length and stores it in B<rnd>.
+BN_rand_ex() generate a cryptographically strong pseudo-random
+number of B<bits> in length and stores it in B<rnd> using the random number
+generator for the library context associated with B<ctx>. The parameter B<ctx>
+may be NULL in which case the default library context is used.
 If B<bits> is less than zero, or too small to
 accommodate the requirements specified by the B<top> and B<bottom>
 parameters, an error is returned.
@@ -40,11 +47,20 @@ If B<bottom> is B<BN_RAND_BOTTOM_ODD>, the number will be odd; if it
 is B<BN_RAND_BOTTOM_ANY> it can be odd or even.
 If B<bits> is 1 then B<top> cannot also be B<BN_RAND_FLG_TOPTWO>.
 
-BN_rand_range() generates a cryptographically strong pseudo-random
-number B<rnd> in the range 0 E<lt>= B<rnd> E<lt> B<range>.
+BN_rand() is the same as BN_rand_ex() except that the default library context
+is always used.
 
-BN_priv_rand() and BN_priv_rand_range() have the same semantics as
-BN_rand() and BN_rand_range() respectively.  They are intended to be
+BN_rand_range_ex() generates a cryptographically strong pseudo-random
+number B<rnd> in the range 0 E<lt>= B<rnd> E<lt> B<range> using the random number
+generator for the library context associated with B<ctx>. The parameter B<ctx>
+may be NULL in which case the default library context is used.
+
+BN_rand_range() is the same as BN_rand_range_ex() except that the default
+library context is always used.
+
+BN_priv_rand_ex(), BN_priv_rand(), BN_priv_rand_rand_ex() and
+BN_priv_rand_range() have the same semantics as BN_rand_ex(), BN_rand(),
+BN_rand_range_ex() and BN_rand_range() respectively.  They are intended to be
 used for generating values that should remain private, and mirror the
 same difference between L<RAND_bytes(3)> and L<RAND_priv_bytes(3)>.
 
@@ -85,6 +101,11 @@ a future release.
 The
 BN_priv_rand() and BN_priv_rand_range() functions were added in OpenSSL 1.1.1.
 
+=item *
+
+The BN_rand_ex(), BN_priv_rand_ex(), BN_rand_range_ex() and
+BN_priv_rand_range_ex() functions were added in OpenSSL 3.0.
+
 =back
 
 =head1 COPYRIGHT
diff --git a/include/openssl/bn.h b/include/openssl/bn.h
index 377016062d..5c645d58d5 100644
--- a/include/openssl/bn.h
+++ b/include/openssl/bn.h
@@ -206,9 +206,13 @@ void BN_CTX_free(BN_CTX *c);
 void BN_CTX_start(BN_CTX *ctx);
 BIGNUM *BN_CTX_get(BN_CTX *ctx);
 void BN_CTX_end(BN_CTX *ctx);
+int BN_rand_ex(BIGNUM *rnd, int bits, int top, int bottom, BN_CTX *ctx);
 int BN_rand(BIGNUM *rnd, int bits, int top, int bottom);
+int BN_priv_rand_ex(BIGNUM *rnd, int bits, int top, int bottom, BN_CTX *ctx);
 int BN_priv_rand(BIGNUM *rnd, int bits, int top, int bottom);
+int BN_rand_range_ex(BIGNUM *r, const BIGNUM *range, BN_CTX *ctx);
 int BN_rand_range(BIGNUM *rnd, const BIGNUM *range);
+int BN_priv_rand_range_ex(BIGNUM *r, const BIGNUM *range, BN_CTX *ctx);
 int BN_priv_rand_range(BIGNUM *rnd, const BIGNUM *range);
 int BN_pseudo_rand(BIGNUM *rnd, int bits, int top, int bottom);
 int BN_pseudo_rand_range(BIGNUM *rnd, const BIGNUM *range);
diff --git a/util/libcrypto.num b/util/libcrypto.num
index d0031240dc..49d2f22588 100644
--- a/util/libcrypto.num
+++ b/util/libcrypto.num
@@ -4674,3 +4674,7 @@ OPENSSL_thread_stop_ex                  4779	3_0_0	EXIST::FUNCTION:
 OSSL_PARAM_locate_const                 4780	3_0_0	EXIST::FUNCTION:
 X509_REQ_set0_sm2_id                    4781	3_0_0	EXIST::FUNCTION:SM2
 X509_REQ_get0_sm2_id                    4782	3_0_0	EXIST::FUNCTION:SM2
+BN_rand_ex                              4783	3_0_0	EXIST::FUNCTION:
+BN_priv_rand_ex                         4784	3_0_0	EXIST::FUNCTION:
+BN_rand_range_ex                        4785	3_0_0	EXIST::FUNCTION:
+BN_priv_rand_range_ex                   4786	3_0_0	EXIST::FUNCTION: