Add the concept of a child OSSL_LIB_CTX

Add a child OSSL_LIB_CTX that will mirror the providers loaded into the
parent libctx. This is useful for providers that want to use algorithms
from other providers and just need to inherit the providers used by the
application.

Fixes #14925

Reviewed-by: Paul Dale <pauli@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/14991)

1 files changed, 40 insertions, 6 deletions

diff --git a/crypto/provider_core.c b/crypto/provider_core.c
index db8763d50d..3e2e2ac335 100644
--- a/crypto/provider_core.c
+++ b/crypto/provider_core.c
@@ -22,6 +22,7 @@
 #include "internal/provider.h"
 #include "internal/refcount.h"
 #include "internal/bio.h"
+#include "internal/core.h"
 #include "provider_local.h"
 #ifndef FIPS_MODULE
 # include <openssl/self_test.h>
@@ -91,8 +92,12 @@ struct ossl_provider_st {
     size_t operation_bits_sz;
     CRYPTO_RWLOCK *opbits_lock;
 
+    /* Whether this provider is the child of some other provider */
+    unsigned int ischild:1;
+
     /* Provider side data */
     void *provctx;
+    const OSSL_DISPATCH *dispatch;
 };
 DEFINE_STACK_OF(OSSL_PROVIDER)
 
@@ -234,8 +239,13 @@ OSSL_PROVIDER *ossl_provider_find(OSSL_LIB_CTX *libctx, const char *name,
          * Make sure any providers are loaded from config before we try to find
          * them.
          */
-        if (!noconfig && ossl_lib_ctx_is_default(libctx))
-            OPENSSL_init_crypto(OPENSSL_INIT_LOAD_CONFIG, NULL);
+        if (!noconfig) {
+            if (ossl_lib_ctx_is_default(libctx))
+                OPENSSL_init_crypto(OPENSSL_INIT_LOAD_CONFIG, NULL);
+            if (ossl_lib_ctx_is_child(libctx)
+                    && !ossl_provider_init_child_providers(libctx))
+                return NULL;
+        }
 #endif
 
         tmpl.name = (char *)name;
@@ -362,8 +372,7 @@ void ossl_provider_free(OSSL_PROVIDER *prov)
          */
         if (ref == 0) {
             if (prov->flag_initialized) {
-                if (prov->teardown != NULL)
-                    prov->teardown(prov->provctx);
+                ossl_provider_teardown(prov);
 #ifndef OPENSSL_NO_ERR
 # ifndef FIPS_MODULE
                 if (prov->error_strings != NULL) {
@@ -581,6 +590,7 @@ static int provider_init(OSSL_PROVIDER *prov, int flag_lock)
         goto end;
     }
     prov->provctx = tmp_provctx;
+    prov->dispatch = provider_dispatch;
 
     for (; provider_dispatch->function_id != 0; provider_dispatch++) {
         switch (provider_dispatch->function_id) {
@@ -845,6 +855,9 @@ int ossl_provider_doall_activated(OSSL_LIB_CTX *ctx,
      */
     if (ossl_lib_ctx_is_default(ctx))
         OPENSSL_init_crypto(OPENSSL_INIT_LOAD_CONFIG, NULL);
+    if (ossl_lib_ctx_is_child(ctx)
+            && !ossl_provider_init_child_providers(ctx))
+        return 0;
 #endif
 
     if (store == NULL)
@@ -990,6 +1003,14 @@ void *ossl_provider_prov_ctx(const OSSL_PROVIDER *prov)
     return NULL;
 }
 
+const OSSL_DISPATCH *ossl_provider_get0_dispatch(const OSSL_PROVIDER *prov)
+{
+    if (prov != NULL)
+        return prov->dispatch;
+
+    return NULL;
+}
+
 OSSL_LIB_CTX *ossl_provider_libctx(const OSSL_PROVIDER *prov)
 {
     return prov != NULL ? prov->libctx : NULL;
@@ -998,7 +1019,7 @@ OSSL_LIB_CTX *ossl_provider_libctx(const OSSL_PROVIDER *prov)
 /* Wrappers around calls to the provider */
 void ossl_provider_teardown(const OSSL_PROVIDER *prov)
 {
-    if (prov->teardown != NULL)
+    if (prov->teardown != NULL && !prov->ischild)
         prov->teardown(prov->provctx);
 }
 
@@ -1133,6 +1154,11 @@ int ossl_provider_test_operation_bit(OSSL_PROVIDER *provider, size_t bitnum,
     return 1;
 }
 
+void ossl_provider_set_child(OSSL_PROVIDER *prov)
+{
+    prov->ischild = 1;
+}
+
 /*-
  * Core functions for the provider
  * ===============================
@@ -1350,7 +1376,15 @@ static const OSSL_DISPATCH core_dispatch_[] = {
     { OSSL_FUNC_CRYPTO_SECURE_ALLOCATED,
         (void (*)(void))CRYPTO_secure_allocated },
     { OSSL_FUNC_OPENSSL_CLEANSE, (void (*)(void))OPENSSL_cleanse },
-
+#ifndef FIPS_MODULE
+    { OSSL_FUNC_CORE_PROVIDER_DO_ALL, (void (*)(void))OSSL_PROVIDER_do_all },
+    { OSSL_FUNC_CORE_PROVIDER_NAME,
+        (void (*)(void))OSSL_PROVIDER_name },
+    { OSSL_FUNC_CORE_PROVIDER_GET0_PROVIDER_CTX,
+        (void (*)(void))OSSL_PROVIDER_get0_provider_ctx },
+    { OSSL_FUNC_CORE_PROVIDER_GET0_DISPATCH,
+        (void (*)(void))OSSL_PROVIDER_get0_dispatch },
+#endif
     { 0, NULL }
 };
 static const OSSL_DISPATCH *core_dispatch = core_dispatch_;