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, 30 insertions, 1 deletions

diff --git a/crypto/context.c b/crypto/context.c
index b21fdf077d..1e0dfa8e01 100644
--- a/crypto/context.c
+++ b/crypto/context.c
@@ -13,6 +13,7 @@
 #include "internal/property.h"
 #include "internal/core.h"
 #include "internal/bio.h"
+#include "internal/provider.h"
 
 struct ossl_lib_ctx_onfree_list_st {
     ossl_lib_ctx_onfree_fn *fn;
@@ -39,6 +40,7 @@ struct ossl_lib_ctx_st {
     int run_once_done[OSSL_LIB_CTX_MAX_RUN_ONCE];
     int run_once_ret[OSSL_LIB_CTX_MAX_RUN_ONCE];
     struct ossl_lib_ctx_onfree_list_st *onfreelist;
+    unsigned int ischild:1;
 };
 
 int ossl_lib_ctx_write_lock(OSSL_LIB_CTX *ctx)
@@ -56,6 +58,15 @@ int ossl_lib_ctx_unlock(OSSL_LIB_CTX *ctx)
     return CRYPTO_THREAD_unlock(ossl_lib_ctx_get_concrete(ctx)->lock);
 }
 
+int ossl_lib_ctx_is_child(OSSL_LIB_CTX *ctx)
+{
+    ctx = ossl_lib_ctx_get_concrete(ctx);
+
+    if (ctx == NULL)
+        return 0;
+    return ctx->ischild;
+}
+
 static int context_init(OSSL_LIB_CTX *ctx)
 {
     size_t i;
@@ -185,7 +196,8 @@ OSSL_LIB_CTX *OSSL_LIB_CTX_new(void)
 }
 
 #ifndef FIPS_MODULE
-OSSL_LIB_CTX *OSSL_LIB_CTX_new_from_dispatch(const OSSL_DISPATCH *in)
+OSSL_LIB_CTX *OSSL_LIB_CTX_new_from_dispatch(const OSSL_CORE_HANDLE *handle,
+                                             const OSSL_DISPATCH *in)
 {
     OSSL_LIB_CTX *ctx = OSSL_LIB_CTX_new();
 
@@ -200,6 +212,23 @@ OSSL_LIB_CTX *OSSL_LIB_CTX_new_from_dispatch(const OSSL_DISPATCH *in)
     return ctx;
 }
 
+OSSL_LIB_CTX *OSSL_LIB_CTX_new_child(const OSSL_CORE_HANDLE *handle,
+                                     const OSSL_DISPATCH *in)
+{
+    OSSL_LIB_CTX *ctx = OSSL_LIB_CTX_new_from_dispatch(handle, in);
+
+    if (ctx == NULL)
+        return NULL;
+
+    if (!ossl_provider_init_as_child(ctx, handle, in)) {
+        OSSL_LIB_CTX_free(ctx);
+        return NULL;
+    }
+    ctx->ischild = 1;
+
+    return ctx;
+}
+
 int OSSL_LIB_CTX_load_config(OSSL_LIB_CTX *ctx, const char *config_file)
 {
     return CONF_modules_load_file_ex(ctx, config_file, NULL, 0) > 0;