/*

 * Copyright 2001-2022 The OpenSSL Project Authors. All Rights Reserved.

 *

 * Licensed under the OpenSSL license (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 "eng_local.h"

#include "internal/dso.h"

#include <openssl/crypto.h>

/*

 * Shared libraries implementing ENGINEs for use by the "dynamic" ENGINE

 * loader should implement the hook-up functions with the following

 * prototypes.

 */

/* Our ENGINE handlers */

static int dynamic_init(ENGINE *e);

static int dynamic_finish(ENGINE *e);

static int dynamic_ctrl(ENGINE *e, int cmd, long i, void *p,

                        void (*f) (void));

/* Predeclare our context type */

typedef struct st_dynamic_data_ctx dynamic_data_ctx;

/* The implementation for the important control command */

static int dynamic_load(ENGINE *e, dynamic_data_ctx *ctx);

#define DYNAMIC_CMD_SO_PATH             ENGINE_CMD_BASE

#define DYNAMIC_CMD_NO_VCHECK           (ENGINE_CMD_BASE + 1)

#define DYNAMIC_CMD_ID                  (ENGINE_CMD_BASE + 2)

#define DYNAMIC_CMD_LIST_ADD            (ENGINE_CMD_BASE + 3)

#define DYNAMIC_CMD_DIR_LOAD            (ENGINE_CMD_BASE + 4)

#define DYNAMIC_CMD_DIR_ADD             (ENGINE_CMD_BASE + 5)

#define DYNAMIC_CMD_LOAD                (ENGINE_CMD_BASE + 6)

/* The constants used when creating the ENGINE */

static const char *engine_dynamic_id = "dynamic";

static const char *engine_dynamic_name = "Dynamic engine loading support";

static const ENGINE_CMD_DEFN dynamic_cmd_defns[] = {

    {DYNAMIC_CMD_SO_PATH,

     "SO_PATH",

     "Specifies the path to the new ENGINE shared library",

     ENGINE_CMD_FLAG_STRING},

    {DYNAMIC_CMD_NO_VCHECK,

     "NO_VCHECK",

     "Specifies to continue even if version checking fails (boolean)",

     ENGINE_CMD_FLAG_NUMERIC},

    {DYNAMIC_CMD_ID,

     "ID",

     "Specifies an ENGINE id name for loading",

     ENGINE_CMD_FLAG_STRING},

    {DYNAMIC_CMD_LIST_ADD,

     "LIST_ADD",

     "Whether to add a loaded ENGINE to the internal list (0=no,1=yes,2=mandatory)",

     ENGINE_CMD_FLAG_NUMERIC},

    {DYNAMIC_CMD_DIR_LOAD,

     "DIR_LOAD",

     "Specifies whether to load from 'DIR_ADD' directories (0=no,1=yes,2=mandatory)",

     ENGINE_CMD_FLAG_NUMERIC},

    {DYNAMIC_CMD_DIR_ADD,

     "DIR_ADD",

     "Adds a directory from which ENGINEs can be loaded",

     ENGINE_CMD_FLAG_STRING},

    {DYNAMIC_CMD_LOAD,

     "LOAD",

     "Load up the ENGINE specified by other settings",

     ENGINE_CMD_FLAG_NO_INPUT},

    {0, NULL, NULL, 0}

};

/*

 * Loading code stores state inside the ENGINE structure via the "ex_data"

 * element. We load all our state into a single structure and use that as a

 * single context in the "ex_data" stack.

 */

struct st_dynamic_data_ctx {

    /* The DSO object we load that supplies the ENGINE code */

    DSO *dynamic_dso;

    /*

     * The function pointer to the version checking shared library function

     */

    dynamic_v_check_fn v_check;

    /*

     * The function pointer to the engine-binding shared library function

     */

    dynamic_bind_engine bind_engine;

    /* The default name/path for loading the shared library */

    char *DYNAMIC_LIBNAME;

    /* Whether to continue loading on a version check failure */

    int no_vcheck;

    /* If non-NULL, stipulates the 'id' of the ENGINE to be loaded */

    char *engine_id;

    /*

     * If non-zero, a successfully loaded ENGINE should be added to the

     * internal ENGINE list. If 2, the add must succeed or the entire load

     * should fail.

     */

    int list_add_value;

    /* The symbol name for the version checking function */

    const char *DYNAMIC_F1;

    /* The symbol name for the "initialise ENGINE structure" function */

    const char *DYNAMIC_F2;

    /*

     * Whether to never use 'dirs', use 'dirs' as a fallback, or only use

     * 'dirs' for loading. Default is to use 'dirs' as a fallback.

     */

    int dir_load;

    /* A stack of directories from which ENGINEs could be loaded */

    STACK_OF(OPENSSL_STRING) *dirs;

};

/*

 * This is the "ex_data" index we obtain and reserve for use with our context

 * structure.

 */

static int dynamic_ex_data_idx = -1;

static void int_free_str(char *s)

{

    OPENSSL_free(s);

}

/*

 * Because our ex_data element may or may not get allocated depending on

 * whether a "first-use" occurs before the ENGINE is freed, we have a memory

 * leak problem to solve. We can't declare a "new" handler for the ex_data as

 * we don't want a dynamic_data_ctx in *all* ENGINE structures of all types

 * (this is a bug in the design of CRYPTO_EX_DATA). As such, we just declare

 * a "free" handler and that will get called if an ENGINE is being destroyed

 * and there was an ex_data element corresponding to our context type.

 */

static void dynamic_data_ctx_free_func(void *parent, void *ptr,

                                       CRYPTO_EX_DATA *ad, int idx, long argl,

                                       void *argp)

{

    if (ptr) {

        dynamic_data_ctx *ctx = (dynamic_data_ctx *)ptr;

        DSO_free(ctx->dynamic_dso);

        OPENSSL_free(ctx->DYNAMIC_LIBNAME);

        OPENSSL_free(ctx->engine_id);

        sk_OPENSSL_STRING_pop_free(ctx->dirs, int_free_str);

        OPENSSL_free(ctx);

    }

}

/*

 * Construct the per-ENGINE context. We create it blindly and then use a lock

 * to check for a race - if so, all but one of the threads "racing" will have

 * wasted their time. The alternative involves creating everything inside the

 * lock which is far worse.

 */

static int dynamic_set_data_ctx(ENGINE *e, dynamic_data_ctx **ctx)

{

    dynamic_data_ctx *c = OPENSSL_zalloc(sizeof(*c));

    int ret = 1;

    if (c == NULL) {

        ENGINEerr(ENGINE_F_DYNAMIC_SET_DATA_CTX, ERR_R_MALLOC_FAILURE);

        return 0;

    }

    c->dirs = sk_OPENSSL_STRING_new_null();

    if (c->dirs == NULL) {

        ENGINEerr(ENGINE_F_DYNAMIC_SET_DATA_CTX, ERR_R_MALLOC_FAILURE);

        OPENSSL_free(c);

        return 0;

    }

    c->DYNAMIC_F1 = "v_check";

    c->DYNAMIC_F2 = "bind_engine";

    c->dir_load = 1;

    CRYPTO_THREAD_write_lock(global_engine_lock);

    if ((*ctx = (dynamic_data_ctx *)ENGINE_get_ex_data(e,

                                                       dynamic_ex_data_idx))

        == NULL) {

        /* Good, we're the first */

        ret = ENGINE_set_ex_data(e, dynamic_ex_data_idx, c);

        if (ret) {

            *ctx = c;

            c = NULL;

        }

    }

    CRYPTO_THREAD_unlock(global_engine_lock);

    /*

     * If we lost the race to set the context, c is non-NULL and *ctx is the

     * context of the thread that won.

     */

    if (c)

        sk_OPENSSL_STRING_free(c->dirs);

    OPENSSL_free(c);

    return ret;

}

/*

 * This function retrieves the context structure from an ENGINE's "ex_data",

 * or if it doesn't exist yet, sets it up.

 */

static dynamic_data_ctx *dynamic_get_data_ctx(ENGINE *e)

{

    dynamic_data_ctx *ctx;

    if (dynamic_ex_data_idx < 0) {

        /*

         * Create and register the ENGINE ex_data, and associate our "free"

         * function with it to ensure any allocated contexts get freed when

         * an ENGINE goes underground.

         */

        int new_idx = ENGINE_get_ex_new_index(0, NULL, NULL, NULL,

                                              dynamic_data_ctx_free_func);

        if (new_idx == -1) {

            ENGINEerr(ENGINE_F_DYNAMIC_GET_DATA_CTX, ENGINE_R_NO_INDEX);

            return NULL;

        }

        CRYPTO_THREAD_write_lock(global_engine_lock);

        /* Avoid a race by checking again inside this lock */

        if (dynamic_ex_data_idx < 0) {

            /* Good, someone didn't beat us to it */

            dynamic_ex_data_idx = new_idx;

            new_idx = -1;

        }

        CRYPTO_THREAD_unlock(global_engine_lock);

        /*

         * In theory we could "give back" the index here if (new_idx>-1), but

         * it's not possible and wouldn't gain us much if it were.

         */

    }

    ctx = (dynamic_data_ctx *)ENGINE_get_ex_data(e, dynamic_ex_data_idx);

    /* Check if the context needs to be created */

    if ((ctx == NULL) && !dynamic_set_data_ctx(e, &ctx))

        /* "set_data" will set errors if necessary */

        return NULL;

    return ctx;

}

static ENGINE *engine_dynamic(void)

{

    ENGINE *ret = ENGINE_new();

    if (ret == NULL)

        return NULL;

    if (!ENGINE_set_id(ret, engine_dynamic_id) ||

        !ENGINE_set_name(ret, engine_dynamic_name) ||

        !ENGINE_set_init_function(ret, dynamic_init) ||

        !ENGINE_set_finish_function(ret, dynamic_finish) ||

        !ENGINE_set_ctrl_function(ret, dynamic_ctrl) ||

        !ENGINE_set_flags(ret, ENGINE_FLAGS_BY_ID_COPY) ||

        !ENGINE_set_cmd_defns(ret, dynamic_cmd_defns)) {

        ENGINE_free(ret);

        return NULL;

    }

    return ret;

}

void engine_load_dynamic_int(void)

{

    ENGINE *toadd = engine_dynamic();

    if (!toadd)

        return;

    ENGINE_add(toadd);

    /*

     * If the "add" worked, it gets a structural reference. So either way, we

     * release our just-created reference.

     */

    ENGINE_free(toadd);

    /*

     * If the "add" didn't work, it was probably a conflict because it was

     * already added (eg. someone calling ENGINE_load_blah then calling

     * ENGINE_load_builtin_engines() perhaps).

     */

    ERR_clear_error();

}

static int dynamic_init(ENGINE *e)

{

    /*

     * We always return failure - the "dynamic" engine itself can't be used

     * for anything.

     */

    return 0;

}

static int dynamic_finish(ENGINE *e)

{

    /*

     * This should never be called on account of "dynamic_init" always

     * failing.

     */

    return 0;

}

static int dynamic_ctrl(ENGINE *e, int cmd, long i, void *p, void (*f) (void))

{

    dynamic_data_ctx *ctx = dynamic_get_data_ctx(e);

    int initialised;

    if (!ctx) {

        ENGINEerr(ENGINE_F_DYNAMIC_CTRL, ENGINE_R_NOT_LOADED);

        return 0;

    }

    initialised = ((ctx->dynamic_dso == NULL) ? 0 : 1);

    /* All our control commands require the ENGINE to be uninitialised */

    if (initialised) {

        ENGINEerr(ENGINE_F_DYNAMIC_CTRL, ENGINE_R_ALREADY_LOADED);

        return 0;

    }

    switch (cmd) {

    case DYNAMIC_CMD_SO_PATH:

        /* a NULL 'p' or a string of zero-length is the same thing */

        if (p && (strlen((const char *)p) < 1))

            p = NULL;

        OPENSSL_free(ctx->DYNAMIC_LIBNAME);

        if (p)

            ctx->DYNAMIC_LIBNAME = OPENSSL_strdup(p);

        else

            ctx->DYNAMIC_LIBNAME = NULL;

        return (ctx->DYNAMIC_LIBNAME ? 1 : 0);

    case DYNAMIC_CMD_NO_VCHECK:

        ctx->no_vcheck = ((i == 0) ? 0 : 1);

        return 1;

    case DYNAMIC_CMD_ID:

        /* a NULL 'p' or a string of zero-length is the same thing */

        if (p && (strlen((const char *)p) < 1))

            p = NULL;

        OPENSSL_free(ctx->engine_id);

        if (p)

            ctx->engine_id = OPENSSL_strdup(p);

        else

            ctx->engine_id = NULL;

        return (ctx->engine_id ? 1 : 0);

    case DYNAMIC_CMD_LIST_ADD:

        if ((i < 0) || (i > 2)) {

            ENGINEerr(ENGINE_F_DYNAMIC_CTRL, ENGINE_R_INVALID_ARGUMENT);

            return 0;

        }

        ctx->list_add_value = (int)i;

        return 1;

    case DYNAMIC_CMD_LOAD:

        return dynamic_load(e, ctx);

    case DYNAMIC_CMD_DIR_LOAD:

        if ((i < 0) || (i > 2)) {

            ENGINEerr(ENGINE_F_DYNAMIC_CTRL, ENGINE_R_INVALID_ARGUMENT);

            return 0;

        }

        ctx->dir_load = (int)i;

        return 1;

    case DYNAMIC_CMD_DIR_ADD:

        /* a NULL 'p' or a string of zero-length is the same thing */

        if (!p || (strlen((const char *)p) < 1)) {

            ENGINEerr(ENGINE_F_DYNAMIC_CTRL, ENGINE_R_INVALID_ARGUMENT);

            return 0;

        }

        {

            char *tmp_str = OPENSSL_strdup(p);

            if (tmp_str == NULL) {

                ENGINEerr(ENGINE_F_DYNAMIC_CTRL, ERR_R_MALLOC_FAILURE);

                return 0;

            }

            if (!sk_OPENSSL_STRING_push(ctx->dirs, tmp_str)) {

                OPENSSL_free(tmp_str);

                ENGINEerr(ENGINE_F_DYNAMIC_CTRL, ERR_R_MALLOC_FAILURE);

                return 0;

            }

        }

        return 1;

    default:

        break;

    }

    ENGINEerr(ENGINE_F_DYNAMIC_CTRL, ENGINE_R_CTRL_COMMAND_NOT_IMPLEMENTED);

    return 0;

}

static int int_load(dynamic_data_ctx *ctx)

{

    int num, loop;

    /* Unless told not to, try a direct load */

    if ((ctx->dir_load != 2) && (DSO_load(ctx->dynamic_dso,

                                          ctx->DYNAMIC_LIBNAME, NULL,

                                          0)) != NULL)

        return 1;

    /* If we're not allowed to use 'dirs' or we have none, fail */

    if (!ctx->dir_load || (num = sk_OPENSSL_STRING_num(ctx->dirs)) < 1)

        return 0;

    for (loop = 0; loop < num; loop++) {

        const char *s = sk_OPENSSL_STRING_value(ctx->dirs, loop);

        char *merge = DSO_merge(ctx->dynamic_dso, ctx->DYNAMIC_LIBNAME, s);

        if (!merge)

            return 0;

        if (DSO_load(ctx->dynamic_dso, merge, NULL, 0)) {

            /* Found what we're looking for */

            OPENSSL_free(merge);

            return 1;

        }

        OPENSSL_free(merge);

    }

    return 0;

}

/*

 * Unfortunately the version checker does not distinguish between

 * engines built for openssl 1.1.x and openssl 3.x, but loading

 * an engine that is built for openssl 3.x will cause a fatal

 * error.  Detect such engines, since EVP_PKEY_get_base_id is exported

 * as a function in openssl 3.x, while it is named EVP_PKEY_base_id

 * in openssl 1.1.x.  Therefore we take the presence of that symbol

 * as an indication that the engine will be incompatible.

 */

static int using_libcrypto_3(dynamic_data_ctx *ctx)

{

    int ret;

    ERR_set_mark();

    ret = DSO_bind_func(ctx->dynamic_dso, "EVP_PKEY_get_base_id") != NULL;

    ERR_pop_to_mark();

    return ret;

}

static int dynamic_load(ENGINE *e, dynamic_data_ctx *ctx)

{

    ENGINE cpy;

    dynamic_fns fns;

    if (ctx->dynamic_dso == NULL)

        ctx->dynamic_dso = DSO_new();

    if (ctx->dynamic_dso == NULL)

        return 0;

    if (!ctx->DYNAMIC_LIBNAME) {

        if (!ctx->engine_id)

            return 0;

        DSO_ctrl(ctx->dynamic_dso, DSO_CTRL_SET_FLAGS,

                 DSO_FLAG_NAME_TRANSLATION_EXT_ONLY, NULL);

        ctx->DYNAMIC_LIBNAME =

            DSO_convert_filename(ctx->dynamic_dso, ctx->engine_id);

    }

    if (!int_load(ctx)) {

        ENGINEerr(ENGINE_F_DYNAMIC_LOAD, ENGINE_R_DSO_NOT_FOUND);

        DSO_free(ctx->dynamic_dso);

        ctx->dynamic_dso = NULL;

        return 0;

    }

    /* We have to find a bind function otherwise it'll always end badly */

    if (!

        (ctx->bind_engine =

         (dynamic_bind_engine) DSO_bind_func(ctx->dynamic_dso,

                                             ctx->DYNAMIC_F2))) {

        ctx->bind_engine = NULL;

        DSO_free(ctx->dynamic_dso);

        ctx->dynamic_dso = NULL;

        ENGINEerr(ENGINE_F_DYNAMIC_LOAD, ENGINE_R_DSO_FAILURE);

        return 0;

    }

    /* Do we perform version checking? */

    if (!ctx->no_vcheck) {

        unsigned long vcheck_res = 0;

        /*

         * Now we try to find a version checking function and decide how to

         * cope with failure if/when it fails.

         */

        ctx->v_check =

            (dynamic_v_check_fn) DSO_bind_func(ctx->dynamic_dso,

                                               ctx->DYNAMIC_F1);

        if (ctx->v_check)

            vcheck_res = ctx->v_check(OSSL_DYNAMIC_VERSION);

        /*

         * We fail if the version checker veto'd the load *or* if it is

         * deferring to us (by returning its version) and we think it is too

         * old. Also fail if this is engine for openssl 3.x.

         */

        if (vcheck_res < OSSL_DYNAMIC_OLDEST || using_libcrypto_3(ctx)) {

            /* Fail */

            ctx->bind_engine = NULL;

            ctx->v_check = NULL;

            DSO_free(ctx->dynamic_dso);

            ctx->dynamic_dso = NULL;

            ENGINEerr(ENGINE_F_DYNAMIC_LOAD,

                      ENGINE_R_VERSION_INCOMPATIBILITY);

            return 0;

        }

    }

    /*

     * First binary copy the ENGINE structure so that we can roll back if the

     * hand-over fails

     */

    memcpy(&cpy, e, sizeof(ENGINE));

    /*

     * Provide the ERR, "ex_data", memory, and locking callbacks so the

     * loaded library uses our state rather than its own. FIXME: As noted in

     * engine.h, much of this would be simplified if each area of code

     * provided its own "summary" structure of all related callbacks. It

     * would also increase opaqueness.

     */

    fns.static_state = ENGINE_get_static_state();

    CRYPTO_get_mem_functions(&fns.mem_fns.malloc_fn, &fns.mem_fns.realloc_fn,

                             &fns.mem_fns.free_fn);

    /*

     * Now that we've loaded the dynamic engine, make sure no "dynamic"

     * ENGINE elements will show through.

     */

    engine_set_all_null(e);

    /* Try to bind the ENGINE onto our own ENGINE structure */

    if (!engine_add_dynamic_id(e, (ENGINE_DYNAMIC_ID)ctx->bind_engine, 1)

            || !ctx->bind_engine(e, ctx->engine_id, &fns)) {

        engine_remove_dynamic_id(e, 1);

        ctx->bind_engine = NULL;

        ctx->v_check = NULL;

        DSO_free(ctx->dynamic_dso);

        ctx->dynamic_dso = NULL;

        ENGINEerr(ENGINE_F_DYNAMIC_LOAD, ENGINE_R_INIT_FAILED);

        /* Copy the original ENGINE structure back */

        memcpy(e, &cpy, sizeof(ENGINE));

        return 0;

    }

    /* Do we try to add this ENGINE to the internal list too? */

    if (ctx->list_add_value > 0) {

        if (!ENGINE_add(e)) {

            /* Do we tolerate this or fail? */

            if (ctx->list_add_value > 1) {

                /*

                 * Fail - NB: By this time, it's too late to rollback, and

                 * trying to do so allows the bind_engine() code to have

                 * created leaks. We just have to fail where we are, after

                 * the ENGINE has changed.

                 */

                ENGINEerr(ENGINE_F_DYNAMIC_LOAD,

                          ENGINE_R_CONFLICTING_ENGINE_ID);

                return 0;

            }

            /* Tolerate */

            ERR_clear_error();

        }

    }

    return 1;

}