path: root/crypto/evp/evp_fetch.c

/*
 * Copyright 2019-2020 The OpenSSL Project Authors. All Rights Reserved.
 *
 * Licensed under the Apache License 2.0 (the "License").  You may not use
 * this file except in compliance with the License.  You can obtain a copy
 * in the file LICENSE in the source distribution or at
 * https://www.openssl.org/source/license.html
 */

#include <stddef.h>
#include <openssl/types.h>
#include <openssl/evp.h>
#include <openssl/core.h>
#include "internal/cryptlib.h"
#include "internal/thread_once.h"
#include "internal/property.h"
#include "internal/core.h"
#include "internal/provider.h"
#include "internal/namemap.h"
#include "crypto/evp.h"    /* evp_local.h needs it */
#include "evp_local.h"

#define NAME_SEPARATOR ':'

static void evp_method_store_free(void *vstore)
{
    ossl_method_store_free(vstore);
}

static void *evp_method_store_new(OPENSSL_CTX *ctx)
{
    return ossl_method_store_new(ctx);
}


static const OPENSSL_CTX_METHOD evp_method_store_method = {
    evp_method_store_new,
    evp_method_store_free,
};

/* Data to be passed through ossl_method_construct() */
struct evp_method_data_st {
    OPENSSL_CTX *libctx;
    OSSL_METHOD_CONSTRUCT_METHOD *mcm;
    int operation_id;            /* For get_evp_method_from_store() */
    int name_id;                 /* For get_evp_method_from_store() */
    const char *names;           /* For get_evp_method_from_store() */
    const char *propquery;       /* For get_evp_method_from_store() */
    void *(*method_from_dispatch)(int name_id, const OSSL_DISPATCH *,
                                  OSSL_PROVIDER *);
    int (*refcnt_up_method)(void *method);
    void (*destruct_method)(void *method);
};

/*
 * Generic routines to fetch / create EVP methods with ossl_method_construct()
 */
static void *alloc_tmp_evp_method_store(OPENSSL_CTX *ctx)
{
    return ossl_method_store_new(ctx);
}

 static void dealloc_tmp_evp_method_store(void *store)
{
    if (store != NULL)
        ossl_method_store_free(store);
}

static OSSL_METHOD_STORE *get_evp_method_store(OPENSSL_CTX *libctx)
{
    return openssl_ctx_get_data(libctx, OPENSSL_CTX_EVP_METHOD_STORE_INDEX,
                                &evp_method_store_method);
}

/*
 * To identify the method in the EVP method store, we mix the name identity
 * with the operation identity, under the assumption that we don't have more
 * than 2^24 names or more than 2^8 operation types.
 *
 * The resulting identity is a 32-bit integer, composed like this:
 *
 * +---------24 bits--------+-8 bits-+
 * |      name identity     | op id  |
 * +------------------------+--------+
 */
static uint32_t evp_method_id(int name_id, unsigned int operation_id)
{
    if (!ossl_assert(name_id > 0 && name_id < (1 << 24))
        || !ossl_assert(operation_id > 0 && operation_id < (1 << 8)))
        return 0;
    return ((name_id << 8) & 0xFFFFFF00) | (operation_id & 0x000000FF);
}

static void *get_evp_method_from_store(OPENSSL_CTX *libctx, void *store,
                                       void *data)
{
    struct evp_method_data_st *methdata = data;
    void *method = NULL;
    int name_id;
    uint32_t meth_id;

    /*
     * get_evp_method_from_store() is only called to try and get the method
     * that evp_generic_fetch() is asking for, and the operation id as well
     * as the name or name id are passed via methdata.
     */
    if ((name_id = methdata->name_id) == 0) {
        OSSL_NAMEMAP *namemap = ossl_namemap_stored(libctx);
        const char *names = methdata->names;
        const char *q = strchr(names, NAME_SEPARATOR);
        size_t l = (q == NULL ? strlen(names) : (size_t)(q - names));

        if (namemap == 0)
            return NULL;
        name_id = ossl_namemap_name2num_n(namemap, names, l);
    }

    if (name_id == 0
        || (meth_id = evp_method_id(name_id, methdata->operation_id)) == 0)
        return NULL;

    if (store == NULL
        && (store = get_evp_method_store(libctx)) == NULL)
        return NULL;

    if (!ossl_method_store_fetch(store, meth_id, methdata->propquery,
                                 &method))
        return NULL;
    return method;
}

static int put_evp_method_in_store(OPENSSL_CTX *libctx, void *store,
                                   void *method, const OSSL_PROVIDER *prov,
                                   int operation_id, const char *names,
                                   const char *propdef, void *data)
{
    struct evp_method_data_st *methdata = data;
    OSSL_NAMEMAP *namemap;
    int name_id;
    uint32_t meth_id;
    size_t l = 0;

    /*
     * put_evp_method_in_store() is only called with an EVP method that was
     * successfully created by construct_method() below, which means that
     * all the names should already be stored in the namemap with the same
     * numeric identity, so just use the first to get that identity.
     */
    if (names != NULL) {
        const char *q = strchr(names, NAME_SEPARATOR);

        l = (q == NULL ? strlen(names) : (size_t)(q - names));
    }

    if ((namemap = ossl_namemap_stored(libctx)) == NULL
        || (name_id = ossl_namemap_name2num_n(namemap, names, l)) == 0
        || (meth_id = evp_method_id(name_id, operation_id)) == 0)
        return 0;

    if (store == NULL
        && (store = get_evp_method_store(libctx)) == NULL)
        return 0;

    return ossl_method_store_add(store, prov, meth_id, propdef, method,
                                 methdata->refcnt_up_method,
                                 methdata->destruct_method);
}

/*
 * The core fetching functionality passes the name of the implementation.
 * This function is responsible to getting an identity number for it.
 */
static void *construct_evp_method(const OSSL_ALGORITHM *algodef,
                                  OSSL_PROVIDER *prov, void *data)
{
    /*
     * This function is only called if get_evp_method_from_store() returned
     * NULL, so it's safe to say that of all the spots to create a new
     * namemap entry, this is it.  Should the name already exist there, we
     * know that ossl_namemap_add_name() will return its corresponding
     * number.
     */
    struct evp_method_data_st *methdata = data;
    OPENSSL_CTX *libctx = ossl_provider_library_context(prov);
    OSSL_NAMEMAP *namemap = ossl_namemap_stored(libctx);
    const char *names = algodef->algorithm_names;
    int name_id = ossl_namemap_add_names(namemap, 0, names, NAME_SEPARATOR);

    if (name_id == 0)
        return NULL;
    return methdata->method_from_dispatch(name_id, algodef->implementation,
                                          prov);
}

static void destruct_evp_method(void *method, void *data)
{
    struct evp_method_data_st *methdata = data;

    methdata->destruct_method(method);
}

static void *
inner_evp_generic_fetch(OPENSSL_CTX *libctx, int operation_id,
                        int name_id, const char *name,
                        const char *properties,
                        void *(*new_method)(int name_id,
                                            const OSSL_DISPATCH *fns,
                                            OSSL_PROVIDER *prov),
                        int (*up_ref_method)(void *),
                        void (*free_method)(void *))
{
    OSSL_METHOD_STORE *store = get_evp_method_store(libctx);
    OSSL_NAMEMAP *namemap = ossl_namemap_stored(libctx);
    uint32_t meth_id = 0;
    void *method = NULL;

    if (store ==