Refactor OSSL_LIB_CTX to avoid using CRYPTO_EX_DATA

This refactors OSSL_LIB_CTX to avoid using CRYPTO_EX_DATA. The assorted
objects to be managed by OSSL_LIB_CTX are hardcoded and are initialized
eagerly rather than lazily, which avoids the need for locking on access
in most cases.

Fixes #17116.

Reviewed-by: Matt Caswell <matt@openssl.org>
Reviewed-by: Paul Dale <pauli@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/17881)

(cherry picked from commit 927d0566ded0dff9d6c5abc8a40bb84068446b76)

1 files changed, 12 insertions, 69 deletions

diff --git a/doc/internal/man3/ossl_lib_ctx_get_data.pod b/doc/internal/man3/ossl_lib_ctx_get_data.pod
index faedf7275f..2ffd000da1 100644
--- a/doc/internal/man3/ossl_lib_ctx_get_data.pod
+++ b/doc/internal/man3/ossl_lib_ctx_get_data.pod
@@ -11,14 +11,7 @@ ossl_lib_ctx_is_child
  #include <openssl/types.h>
  #include "internal/cryptlib.h"
 
- typedef struct ossl_lib_ctx_method {
-     int priority;
-     void *(*new_func)(OSSL_LIB_CTX *ctx);
-     void (*free_func)(void *);
- } OSSL_LIB_CTX_METHOD;
-
- void *ossl_lib_ctx_get_data(OSSL_LIB_CTX *ctx, int index,
-                             const OSSL_LIB_CTX_METHOD *meth);
+ void *ossl_lib_ctx_get_data(OSSL_LIB_CTX *ctx, int index);
 
  int ossl_lib_ctx_run_once(OSSL_LIB_CTX *ctx, unsigned int idx,
                            ossl_lib_ctx_run_once_fn run_once_fn);
@@ -28,38 +21,24 @@ ossl_lib_ctx_is_child
 
 =head1 DESCRIPTION
 
-Internally, the OpenSSL library context B<OSSL_LIB_CTX> is implemented
-as a B<CRYPTO_EX_DATA>, which allows data from diverse parts of the
-library to be added and removed dynamically.
-Each such data item must have a corresponding CRYPTO_EX_DATA index
-associated with it. Unlike normal CRYPTO_EX_DATA objects we use static indexes
-to identify data items. These are mapped transparently to CRYPTO_EX_DATA dynamic
-indexes internally to the implementation.
-See the example further down to see how that's done.
-
-ossl_lib_ctx_get_data() is used to retrieve a pointer to the data in
-the library context I<ctx> associated with the given I<index>. An
-OSSL_LIB_CTX_METHOD must be defined and given in the I<meth> parameter. The index
-for it should be defined in cryptlib.h. The functions through the method are
-used to create or free items that are stored at that index whenever a library
-context is created or freed, meaning that the code that use a data item of that
-index doesn't have to worry about that, just use the data available.
-
-Deallocation of an index happens automatically when the library
-context is freed.
-
-ossl_lib_ctx_run_once is used to run some initialisation routine I<run_once_fn>
+ossl_lib_ctx_run_once() is used to run some initialisation routine I<run_once_fn>
 exactly once per library context I<ctx> object. Each initialisation routine
 should be allocate a unique run once index in cryptlib.h.
 
 Any resources allocated via a run once initialisation routine can be cleaned up
-using ossl_lib_ctx_onfree. This associates an "on free" routine I<onfreefn> with
+using ossl_lib_ctx_onfree(). This associates an "on free" routine I<onfreefn> with
 the library context I<ctx>. When I<ctx> is freed all associated "on free"
 routines are called.
 
 ossl_lib_ctx_is_child() returns 1 if this library context is a child and 0
 otherwise.
 
+ossl_lib_ctx_get_data() allows different parts of the library to retrieve
+pointers to structures used in diverse parts of the library. The lifetime of
+these structures is managed by B<OSSL_LIB_CTX>. The different objects which can
+be retrieved are specified with the given argument I<index>. The valid values of
+I<index> are specified in cryptlib.h.
+
 =head1 RETURN VALUES
 
 ossl_lib_ctx_get_data() returns a pointer on success, or NULL on
@@ -67,51 +46,15 @@ failure.
 
 =head1 EXAMPLES
 
-=head2 Initialization
-
-For a type C<FOO> that should end up in the OpenSSL library context, a
-small bit of initialization is needed, i.e. to associate a constructor
-and a destructor to an index.
-
- typedef struct foo_st {
-     int i;
-     void *data;
- } FOO;
-
- static void *foo_new(OSSL_LIB_CTX *ctx)
- {
-     FOO *ptr = OPENSSL_zalloc(sizeof(*foo));
-     if (ptr != NULL)
-         ptr->i = 42;
-     return ptr;
- }
- static void foo_free(void *ptr)
- {
-     OPENSSL_free(ptr);
- }
-
- /*
-  * Include a reference to this in the methods table in context.c
-  * OSSL_LIB_CTX_FOO_INDEX should be added to internal/cryptlib.h
-  * Priorities can be OSSL_LIB_CTX_METHOD_DEFAULT_PRIORITY,
-  * OSSL_LIB_CTX_METHOD_PRIORITY_1, OSSL_LIB_CTX_METHOD_PRIORITY_2, etc.
-  * Default priority is low (0). The higher the priority the earlier the
-  * method's destructor will be called when the library context is cleaned up.
-  */
- const OSSL_LIB_CTX_METHOD foo_method = {
-     OSSL_LIB_CTX_METHOD_DEFAULT_PRIORITY,
-     foo_new,
-     foo_free
- };
-
 =head2 Usage
 
-To get and use the data stored in the library context, simply do this:
+To obtain a pointer for an object managed by the library context, simply do
+this:
 
  /*
   * ctx is received from a caller,
   */
- FOO *data = ossl_lib_ctx_get_data(ctx, OSSL_LIB_CTX_FOO_INDEX, &foo_method);
+ FOO *data = ossl_lib_ctx_get_data(ctx, OSSL_LIB_CTX_FOO_INDEX);
 
 =head2 Run Once