rand: add callbacks to cleanup the user entropy resp. nonce

The `get_user_{entropy,nonce}` callbacks were add recently to the
dispatch table in commit 4cde7585ce. Instead of adding corresponding
`cleanup_user_{entropy,nonce}` callbacks, the `cleanup_{entropy,nonce}`
callbacks were reused. This can cause a problem in the case where the
seed source is replaced by a provider: the buffer gets allocated by
the provider but cleared by the core.

Reviewed-by: Tomas Mraz <tomas@openssl.org>
Reviewed-by: Matt Caswell <matt@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/22423)

crypto/provider_core.c

@@ -1930,12 +1930,14 @@ OSSL_FUNC_BIO_free_fn ossl_core_bio_free;
 OSSL_FUNC_BIO_vprintf_fn ossl_core_bio_vprintf;
 OSSL_FUNC_BIO_vsnprintf_fn BIO_vsnprintf;
 static OSSL_FUNC_self_test_cb_fn core_self_test_get_callback;
-static OSSL_FUNC_get_user_entropy_fn rand_get_user_entropy;
 static OSSL_FUNC_get_entropy_fn rand_get_entropy;
+static OSSL_FUNC_get_user_entropy_fn rand_get_user_entropy;
 static OSSL_FUNC_cleanup_entropy_fn rand_cleanup_entropy;
-static OSSL_FUNC_get_user_nonce_fn rand_get_user_nonce;
+static OSSL_FUNC_cleanup_user_entropy_fn rand_cleanup_user_entropy;
 static OSSL_FUNC_get_nonce_fn rand_get_nonce;
+static OSSL_FUNC_get_user_nonce_fn rand_get_user_nonce;
 static OSSL_FUNC_cleanup_nonce_fn rand_cleanup_nonce;
+static OSSL_FUNC_cleanup_user_nonce_fn rand_cleanup_user_nonce;
 #endif
 OSSL_FUNC_CRYPTO_malloc_fn CRYPTO_malloc;
 OSSL_FUNC_CRYPTO_zalloc_fn CRYPTO_zalloc;
@@ -2119,6 +2121,13 @@ static void rand_cleanup_entropy(const OSSL_CORE_HANDLE *handle,
                               buf, len);
 }
 
+static void rand_cleanup_user_entropy(const OSSL_CORE_HANDLE *handle,
+                                      unsigned char *buf, size_t len)
+{
+    ossl_rand_cleanup_user_entropy((OSSL_LIB_CTX *)core_get_libctx(handle),
+                                   buf, len);
+}
+
 static size_t rand_get_nonce(const OSSL_CORE_HANDLE *handle,
                              unsigned char **pout,
                              size_t min_len, size_t max_len,
@@ -2144,6 +2153,13 @@ static void rand_cleanup_nonce(const OSSL_CORE_HANDLE *handle,
                             buf, len);
 }
 
+static void rand_cleanup_user_nonce(const OSSL_CORE_HANDLE *handle,
+                               unsigned char *buf, size_t len)
+{
+    ossl_rand_cleanup_user_nonce((OSSL_LIB_CTX *)core_get_libctx(handle),
+                                 buf, len);
+}
+
 static const char *core_provider_get0_name(const OSSL_CORE_HANDLE *prov)
 {
     return OSSL_PROVIDER_get0_name((const OSSL_PROVIDER *)prov);
@@ -2238,11 +2254,13 @@ static const OSSL_DISPATCH core_dispatch_[] = {
     { OSSL_FUNC_BIO_VSNPRINTF, (void (*)(void))BIO_vsnprintf },
     { OSSL_FUNC_SELF_TEST_CB, (void (*)(void))core_self_test_get_callback },
     { OSSL_FUNC_GET_ENTROPY, (void (*)(void))rand_get_entropy },
-    { OSSL_FUNC_CLEANUP_ENTROPY, (void (*)(void))rand_cleanup_entropy },
-    { OSSL_FUNC_GET_NONCE, (void (*)(void))rand_get_nonce },
-    { OSSL_FUNC_CLEANUP_NONCE, (void (*)(void))rand_cleanup_nonce },
     { OSSL_FUNC_GET_USER_ENTROPY, (void (*)(void))rand_get_user_entropy },
+    { OSSL_FUNC_CLEANUP_ENTROPY, (void (*)(void))rand_cleanup_entropy },
+    { OSSL_FUNC_CLEANUP_USER_ENTROPY, (void (*)(void))rand_cleanup_user_entropy },
+    { OSSL_FUNC_GET_NONCE, (void (*)(void))rand_get_nonce },
     { OSSL_FUNC_GET_USER_NONCE, (void (*)(void))rand_get_user_nonce },
+    { OSSL_FUNC_CLEANUP_NONCE, (void (*)(void))rand_cleanup_nonce },
+    { OSSL_FUNC_CLEANUP_USER_NONCE, (void (*)(void))rand_cleanup_user_nonce },
 #endif
     { OSSL_FUNC_CRYPTO_MALLOC, (void (*)(void))CRYPTO_malloc },
     { OSSL_FUNC_CRYPTO_ZALLOC, (void (*)(void))CRYPTO_zalloc },

crypto/rand/prov_seed.c

@@ -77,6 +77,12 @@ void ossl_rand_cleanup_entropy(ossl_unused OSSL_LIB_CTX *ctx,
     OPENSSL_secure_clear_free(buf, len);
 }
 
+void ossl_rand_cleanup_user_entropy(OSSL_LIB_CTX *ctx,
+                                    unsigned char *buf, size_t len)
+{
+    OPENSSL_secure_clear_free(buf, len);
+}
+
 size_t ossl_rand_get_nonce(ossl_unused OSSL_LIB_CTX *ctx,
                            unsigned char **pout,
                            size_t min_len, ossl_unused size_t max_len,
@@ -130,3 +136,9 @@ void ossl_rand_cleanup_nonce(ossl_unused OSSL_LIB_CTX *ctx,
 {
     OPENSSL_clear_free(buf, len);
 }
+
+void ossl_rand_cleanup_user_nonce(ossl_unused OSSL_LIB_CTX *ctx,
+                                  unsigned char *buf, size_t len)
+{
+    OPENSSL_clear_free(buf, len);
+}

doc/internal/man3/ossl_rand_get_entropy.pod

@@ -2,8 +2,10 @@
 
 =head1 NAME
 
-ossl_rand_get_entropy, ossl_rand_get_user_entropy, ossl_rand_cleanup_entropy,
+ossl_rand_get_entropy, ossl_rand_get_user_entropy,
-ossl_rand_get_nonce, ossl_rand_get_user_nonce, ossl_rand_cleanup_nonce
+ossl_rand_cleanup_entropy, ossl_rand_cleanup_user_entropy,
+ossl_rand_get_nonce, ossl_rand_get_user_nonce,
+ossl_rand_cleanup_nonce, ossl_rand_cleanup_user_nonce
 - get seed material from the operating system
 
 =head1 SYNOPSIS
@@ -18,6 +20,8 @@ ossl_rand_get_nonce, ossl_rand_get_user_nonce, ossl_rand_cleanup_nonce
                                    size_t min_len, size_t max_len);
  void ossl_rand_cleanup_entropy(OSSL_CORE_HANDLE *handle,
                                 unsigned char *buf, size_t len);
+ void ossl_rand_cleanup_user_entropy(OSSL_CORE_HANDLE *handle,
+                                     unsigned char *buf, size_t len);
  size_t ossl_rand_get_nonce(OSSL_CORE_HANDLE *handle,
                             unsigned char **pout, size_t min_len,
                             size_t max_len, const void *salt, size_t salt_len);
@@ -26,6 +30,8 @@ ossl_rand_get_nonce, ossl_rand_get_user_nonce, ossl_rand_cleanup_nonce
                                  const void *salt, size_t salt_len);
  void ossl_rand_cleanup_nonce(OSSL_CORE_HANDLE *handle,
                               unsigned char *buf, size_t len);
+ void ossl_rand_cleanup_user_nonce(OSSL_CORE_HANDLE *handle,
+                                   unsigned char *buf, size_t len);
 
 =head1 DESCRIPTION
 
@@ -41,8 +47,12 @@ DRBG seed source.  By default this is the operating system but it can
 be changed by calling L<RAND_set_seed_source_type(3)>.
 
 ossl_rand_cleanup_entropy() cleanses and frees any storage allocated by
-ossl_rand_get_entropy() or ossl_rand_get_user_entropy().  The entropy
+ossl_rand_get_entropy().  The entropy buffer is pointed to by I<buf>
-buffer is pointed to by I<buf> and is of length I<len> bytes.
+and is of length I<len> bytes.
+
+ossl_rand_cleanup_user_entropy() cleanses and frees any storage allocated by
+ossl_rand_get_user_entropy().  The entropy buffer is pointed to by I<buf>
+and is of length I<len> bytes.
 
 ossl_rand_get_nonce() retrieves a nonce using the passed I<salt> parameter
 of length I<salt_len> and operating system specific information.
@@ -76,8 +86,9 @@ of bytes in I<*pout> or 0 on error.
 
 =head1 HISTORY
 
-The functions ossl_rand_get_user_entropy() and ossl_rand_get_user_nonce()
+The functions ossl_rand_get_user_entropy(), ossl_rand_get_user_nonce(),
-were added in OpenSSL 3.0.12, 3.1.4 and 3.2.0.
+ossl_rand_cleanup_user_entropy(), and ossl_rand_cleanup_user_nonce()
+were added in OpenSSL 3.1.4 and 3.2.0.
 
 The remaining functions described here were all added in OpenSSL 3.0.
 

doc/man7/provider-base.pod

@@ -81,6 +81,8 @@ provider-base
                          size_t min_len, size_t max_len);
  void cleanup_entropy(const OSSL_CORE_HANDLE *handle,
                       unsigned char *buf, size_t len);
+ void cleanup_user_entropy(const OSSL_CORE_HANDLE *handle,
+                           unsigned char *buf, size_t len);
  size_t get_nonce(const OSSL_CORE_HANDLE *handle,
                   unsigned char **pout, size_t min_len, size_t max_len,
                   const void *salt, size_t salt_len);
@@ -89,6 +91,8 @@ provider-base
                        const void *salt, size_t salt_len);
  void cleanup_nonce(const OSSL_CORE_HANDLE *handle,
                     unsigned char *buf, size_t len);
+ void cleanup_user_nonce(const OSSL_CORE_HANDLE *handle,
+                         unsigned char *buf, size_t len);
 
  /* Functions for querying the providers in the application library context */
  int provider_register_child_cb(const OSSL_CORE_HANDLE *handle,
@@ -179,9 +183,11 @@ provider):
  ossl_rand_get_entropy          OSSL_FUNC_GET_ENTROPY
  ossl_rand_get_user_entropy     OSSL_FUNC_GET_USER_ENTROPY
  ossl_rand_cleanup_entropy      OSSL_FUNC_CLEANUP_ENTROPY
+ ossl_rand_cleanup_user_entropy OSSL_FUNC_CLEANUP_USER_ENTROPY
  ossl_rand_get_nonce            OSSL_FUNC_GET_NONCE
  ossl_rand_get_user_nonce       OSSL_FUNC_GET_USER_NONCE
  ossl_rand_cleanup_nonce        OSSL_FUNC_CLEANUP_NONCE
+ ossl_rand_cleanup_user_nonce   OSSL_FUNC_CLEANUP_USER_NONCE
  provider_register_child_cb     OSSL_FUNC_PROVIDER_REGISTER_CHILD_CB
  provider_deregister_child_cb   OSSL_FUNC_PROVIDER_DEREGISTER_CHILD_CB
  provider_name                  OSSL_FUNC_PROVIDER_NAME
@@ -315,9 +321,12 @@ attempt to gather seed material via the seed source specified by a call to
 L<RAND_set_seed_source_type(3)> or via L<config(5)/Random Configuration>.
 
 cleanup_entropy() is used to clean up and free the buffer returned by
-get_entropy() or get_user_entropy().  The entropy pointer returned by
+get_entropy().  The entropy pointer returned by get_entropy()
-get_entropy() or get_user_entropy() is passed in B<buf> and its length
+is passed in B<buf> and its length in B<len>.
-in B<len>.
+
+cleanup_user_entropy() is used to clean up and free the buffer returned by
+get_user_entropy().  The entropy pointer returned by get_user_entropy()
+is passed in B<buf> and its length in B<len>.
 
 get_nonce() retrieves a nonce using the passed I<salt> parameter
 of length I<salt_len> and operating system specific information.
@@ -331,10 +340,13 @@ get_user_nonce() is the same as get_nonce() except that it will attempt
 to gather seed material via the seed source specified by a call to
 L<RAND_set_seed_source_type(3)> or via L<config(5)/Random Configuration>.
 
-cleanup_nonce() is used to clean up and free the buffer returned
+cleanup_nonce() is used to clean up and free the buffer returned by
-by get_nonce() or get_user_nonce().  The nonce pointer returned by
+get_nonce().  The nonce pointer returned by get_nonce()
-get_nonce() or get_user_nonce() is passed in B<buf> and its length
+is passed in B<buf> and its length in B<len>.
-in B<len>.
+
+cleanup_user_nonce() is used to clean up and free the buffer returned by
+get_user_nonce().  The nonce pointer returned by get_user_nonce()
+is passed in B<buf> and its length in B<len>.
 
 provider_register_child_cb() registers callbacks for being informed about the
 loading and unloading of providers in the application's library context.

include/crypto/rand.h

@@ -116,6 +116,8 @@ size_t ossl_rand_get_user_entropy(OSSL_LIB_CTX *ctx,
                                   size_t min_len, size_t max_len);
 void ossl_rand_cleanup_entropy(OSSL_LIB_CTX *ctx,
                                unsigned char *buf, size_t len);
+void ossl_rand_cleanup_user_entropy(OSSL_LIB_CTX *ctx,
+                                    unsigned char *buf, size_t len);
 size_t ossl_rand_get_nonce(OSSL_LIB_CTX *ctx,
                            unsigned char **pout, size_t min_len, size_t max_len,
                            const void *salt, size_t salt_len);
@@ -124,6 +126,8 @@ size_t ossl_rand_get_user_nonce(OSSL_LIB_CTX *ctx, unsigned char **pout,
                                 const void *salt, size_t salt_len);
 void ossl_rand_cleanup_nonce(OSSL_LIB_CTX *ctx,
                              unsigned char *buf, size_t len);
+void ossl_rand_cleanup_user_nonce(OSSL_LIB_CTX *ctx,
+                                  unsigned char *buf, size_t len);
 
 /*
  * Get seeding material from the operating system sources.

include/openssl/core_dispatch.h

@@ -177,6 +177,8 @@ OSSL_CORE_MAKE_FUNC(int, BIO_ctrl, (OSSL_CORE_BIO *bio,
                                     int cmd, long num, void *ptr))
 
 /* New seeding functions prototypes with the 101-104 series */
+#define OSSL_FUNC_CLEANUP_USER_ENTROPY        96
+#define OSSL_FUNC_CLEANUP_USER_NONCE          97
 #define OSSL_FUNC_GET_USER_ENTROPY            98
 #define OSSL_FUNC_GET_USER_NONCE              99
 
@@ -197,6 +199,8 @@ OSSL_CORE_MAKE_FUNC(size_t, get_user_entropy, (const OSSL_CORE_HANDLE *handle,
                                                size_t min_len, size_t max_len))
 OSSL_CORE_MAKE_FUNC(void, cleanup_entropy, (const OSSL_CORE_HANDLE *handle,
                                             unsigned char *buf, size_t len))
+OSSL_CORE_MAKE_FUNC(void, cleanup_user_entropy, (const OSSL_CORE_HANDLE *handle,
+                                                 unsigned char *buf, size_t len))
 OSSL_CORE_MAKE_FUNC(size_t, get_nonce, (const OSSL_CORE_HANDLE *handle,
                                         unsigned char **pout, size_t min_len,
                                         size_t max_len, const void *salt,
@@ -207,6 +211,8 @@ OSSL_CORE_MAKE_FUNC(size_t, get_user_nonce, (const OSSL_CORE_HANDLE *handle,
                                              size_t salt_len))
 OSSL_CORE_MAKE_FUNC(void, cleanup_nonce, (const OSSL_CORE_HANDLE *handle,
                                           unsigned char *buf, size_t len))
+OSSL_CORE_MAKE_FUNC(void, cleanup_user_nonce, (const OSSL_CORE_HANDLE *handle,
+                                               unsigned char *buf, size_t len))
 
 /* Functions to access the core's providers */
 #define OSSL_FUNC_PROVIDER_REGISTER_CHILD_CB   105

providers/common/provider_seeding.c

@@ -14,9 +14,11 @@
 static OSSL_FUNC_get_entropy_fn *c_get_entropy = NULL;
 static OSSL_FUNC_get_user_entropy_fn *c_get_user_entropy = NULL;
 static OSSL_FUNC_cleanup_entropy_fn *c_cleanup_entropy = NULL;
+static OSSL_FUNC_cleanup_user_entropy_fn *c_cleanup_user_entropy = NULL;
 static OSSL_FUNC_get_nonce_fn *c_get_nonce = NULL;
 static OSSL_FUNC_get_user_nonce_fn *c_get_user_nonce = NULL;
 static OSSL_FUNC_cleanup_nonce_fn *c_cleanup_nonce = NULL;
+static OSSL_FUNC_cleanup_user_nonce_fn *c_cleanup_user_nonce = NULL;
 
 #ifdef FIPS_MODULE
 /*
@@ -56,6 +58,9 @@ int ossl_prov_seeding_from_dispatch(const OSSL_DISPATCH *fns)
         case OSSL_FUNC_CLEANUP_ENTROPY:
             set_func(c_cleanup_entropy, OSSL_FUNC_cleanup_entropy(fns));
             break;
+        case OSSL_FUNC_CLEANUP_USER_ENTROPY:
+            set_func(c_cleanup_user_entropy, OSSL_FUNC_cleanup_user_entropy(fns));
+            break;
         case OSSL_FUNC_GET_NONCE:
             set_func(c_get_nonce, OSSL_FUNC_get_nonce(fns));
             break;
@@ -65,6 +70,9 @@ int ossl_prov_seeding_from_dispatch(const OSSL_DISPATCH *fns)
         case OSSL_FUNC_CLEANUP_NONCE:
             set_func(c_cleanup_nonce, OSSL_FUNC_cleanup_nonce(fns));
             break;
+        case OSSL_FUNC_CLEANUP_USER_NONCE:
+            set_func(c_cleanup_user_nonce, OSSL_FUNC_cleanup_user_nonce(fns));
+            break;
         }
 #undef set_func
     }
@@ -86,8 +94,12 @@ size_t ossl_prov_get_entropy(PROV_CTX *prov_ctx, unsigned char **pout,
 void ossl_prov_cleanup_entropy(PROV_CTX *prov_ctx, unsigned char *buf,
                                size_t len)
 {
-    if (c_cleanup_entropy != NULL)
+    const OSSL_CORE_HANDLE *handle = CORE_HANDLE(prov_ctx);
-        c_cleanup_entropy(CORE_HANDLE(prov_ctx), buf, len);
+
+    if (c_cleanup_user_entropy != NULL)
+        c_cleanup_user_entropy(handle, buf, len);
+    else if (c_cleanup_entropy != NULL)
+        c_cleanup_entropy(handle, buf, len);
 }
 
 size_t ossl_prov_get_nonce(PROV_CTX *prov_ctx, unsigned char **pout,
@@ -105,6 +117,10 @@ size_t ossl_prov_get_nonce(PROV_CTX *prov_ctx, unsigned char **pout,
 
 void ossl_prov_cleanup_nonce(PROV_CTX *prov_ctx, unsigned char *buf, size_t len)
 {
-    if (c_cleanup_nonce != NULL)
+    const OSSL_CORE_HANDLE *handle = CORE_HANDLE(prov_ctx);
-        c_cleanup_nonce(CORE_HANDLE(prov_ctx), buf, len);
+
+    if (c_cleanup_user_nonce != NULL)
+        c_cleanup_user_nonce(handle, buf, len);
+    else if (c_cleanup_nonce != NULL)
+        c_cleanup_nonce(handle, buf, len);
 }