Maintain strict type discipline between the core and providers

A provider could be linked against a different version of libcrypto than
the version of libcrypto that loaded the provider. Different versions of
libcrypto could define opaque types differently. It must never occur that
a type created in one libcrypto is used directly by the other libcrypto.
This will cause crashes.

We can "cheat" for "built-in" providers that are part of libcrypto itself,
because we know that the two libcrypto versions are the same - but not for
other providers.

To ensure this does not occur we use different types names for the handful
of opaque types that are passed between the core and providers.

Reviewed-by: Richard Levitte <levitte@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/11758)

1 files changed, 13 insertions, 6 deletions

diff --git a/providers/defltprov.c b/providers/defltprov.c
index cedbddb80e..4b15a21c0b 100644
--- a/providers/defltprov.c
+++ b/providers/defltprov.c
@@ -552,6 +552,7 @@ static const OSSL_ALGORITHM *deflt_query(void *provctx, int operation_id,
 
 static void deflt_teardown(void *provctx)
 {
+    BIO_meth_free(PROV_CTX_get0_core_bio_method(provctx));
     PROV_CTX_free(provctx);
 }
 
@@ -566,12 +567,13 @@ static const OSSL_DISPATCH deflt_dispatch_table[] = {
 
 OSSL_provider_init_fn ossl_default_provider_init;
 
-int ossl_default_provider_init(const OSSL_PROVIDER *provider,
+int ossl_default_provider_init(const OSSL_CORE_HANDLE *handle,
                                const OSSL_DISPATCH *in,
                                const OSSL_DISPATCH **out,
                                void **provctx)
 {
     OSSL_core_get_library_context_fn *c_get_libctx = NULL;
+    BIO_METHOD *corebiometh;
 
     if (!ossl_prov_bio_from_dispatch(in))
         return 0;
@@ -598,15 +600,20 @@ int ossl_default_provider_init(const OSSL_PROVIDER *provider,
     /*
      * We want to make sure that all calls from this provider that requires
      * a library context use the same context as the one used to call our
-     * functions.  We do that by passing it along as the provider context.
+     * functions.  We do that by passing it along in the provider context.
      *
-     * This is special for built-in providers.  External providers should
+     * This only works for built-in providers.  Most providers should
      * create their own library context.
      */
-    if ((*provctx = PROV_CTX_new()) == NULL)
+    if ((*provctx = PROV_CTX_new()) == NULL
+            || (corebiometh = bio_prov_init_bio_method()) == NULL) {
+        PROV_CTX_free(*provctx);
+        *provctx = NULL;
         return 0;
-    PROV_CTX_set0_library_context(*provctx, c_get_libctx(provider));
-    PROV_CTX_set0_provider(*provctx, provider);
+    }
+    PROV_CTX_set0_library_context(*provctx, (OPENSSL_CTX *)c_get_libctx(handle));
+    PROV_CTX_set0_handle(*provctx, handle);
+    PROV_CTX_set0_core_bio_method(*provctx, corebiometh);
 
     *out = deflt_dispatch_table;