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eng_dyn.c

/* crypto/engine/eng_dyn.c */
/* Written by Geoff Thorpe (geoff@geoffthorpe.net) for the OpenSSL
 * project 2001.
 */
/* ====================================================================
 * Copyright (c) 1999-2001 The OpenSSL Project.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer. 
 *
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 *
 * 3. All advertising materials mentioning features or use of this
 *    software must display the following acknowledgment:
 *    "This product includes software developed by the OpenSSL Project
 *    for use in the OpenSSL Toolkit. (http://www.OpenSSL.org/)"
 *
 * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to
 *    endorse or promote products derived from this software without
 *    prior written permission. For written permission, please contact
 *    licensing@OpenSSL.org.
 *
 * 5. Products derived from this software may not be called "OpenSSL"
 *    nor may "OpenSSL" appear in their names without prior written
 *    permission of the OpenSSL Project.
 *
 * 6. Redistributions of any form whatsoever must retain the following
 *    acknowledgment:
 *    "This product includes software developed by the OpenSSL Project
 *    for use in the OpenSSL Toolkit (http://www.OpenSSL.org/)"
 *
 * THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY
 * EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE OpenSSL PROJECT OR
 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
 * OF THE POSSIBILITY OF SUCH DAMAGE.
 * ====================================================================
 *
 * This product includes cryptographic software written by Eric Young
 * (eay@cryptsoft.com).  This product includes software written by Tim
 * Hudson (tjh@cryptsoft.com).
 *
 */


#include "eng_int.h"
#include <openssl/dso.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}
      };
static const ENGINE_CMD_DEFN dynamic_cmd_defns_empty[] = {
      {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 */
      const 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 */
      const 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 *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(void *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;
            if(ctx->dynamic_dso)
                  DSO_free(ctx->dynamic_dso);
            if(ctx->DYNAMIC_LIBNAME)
                  OPENSSL_free((void*)ctx->DYNAMIC_LIBNAME);
            if(ctx->engine_id)
                  OPENSSL_free((void*)ctx->engine_id);
            if(ctx->dirs)
                  sk_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;
      c = OPENSSL_malloc(sizeof(dynamic_data_ctx));
      if(!c)
            {
            ENGINEerr(ENGINE_F_DYNAMIC_SET_DATA_CTX,ERR_R_MALLOC_FAILURE);
            return 0;
            }
      memset(c, 0, sizeof(dynamic_data_ctx));
      c->dynamic_dso = NULL;
      c->v_check = NULL;
      c->bind_engine = NULL;
      c->DYNAMIC_LIBNAME = NULL;
      c->no_vcheck = 0;
      c->engine_id = NULL;
      c->list_add_value = 0;
      c->DYNAMIC_F1 = "v_check";
      c->DYNAMIC_F2 = "bind_engine";
      c->dir_load = 1;
      c->dirs = sk_new_null();
      if(!c->dirs)
            {
            ENGINEerr(ENGINE_F_DYNAMIC_SET_DATA_CTX,ERR_R_MALLOC_FAILURE);
            OPENSSL_free(c);
            return 0;
            }
      CRYPTO_w_lock(CRYPTO_LOCK_ENGINE);
      if((*ctx = (dynamic_data_ctx *)ENGINE_get_ex_data(e,
                        dynamic_ex_data_idx)) == NULL)
            {
            /* Good, we're the first */
            ENGINE_set_ex_data(e, dynamic_ex_data_idx, c);
            *ctx = c;
            c = NULL;
            }
      CRYPTO_w_unlock(CRYPTO_LOCK_ENGINE);
      /* 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)
            OPENSSL_free(c);
      return 1;
      }

/* 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_w_lock(CRYPTO_LOCK_ENGINE);
            /* 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_w_unlock(CRYPTO_LOCK_ENGINE);
            /* 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)
            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(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 "dyanamic" 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;
            if(ctx->DYNAMIC_LIBNAME)
                  OPENSSL_free((void*)ctx->DYNAMIC_LIBNAME);
            if(p)
                  ctx->DYNAMIC_LIBNAME = BUF_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;
            if(ctx->engine_id)
                  OPENSSL_free((void*)ctx->engine_id);
            if(p)
                  ctx->engine_id = BUF_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 = BUF_strdup(p);
            if(!tmp_str)
                  {
                  ENGINEerr(ENGINE_F_DYNAMIC_CTRL,
                        ERR_R_MALLOC_FAILURE);
                  return 0;
                  }
            sk_insert(ctx->dirs, tmp_str, -1);
            }
            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_num(ctx->dirs)) < 1))
            return 0;
      for(loop = 0; loop < num; loop++)
            {
            const char *s = sk_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;
      }

static int dynamic_load(ENGINE *e, dynamic_data_ctx *ctx)
      {
      ENGINE cpy;
      dynamic_fns fns;

      if(!ctx->dynamic_dso)
            ctx->dynamic_dso = DSO_new();
      if(!ctx->DYNAMIC_LIBNAME)
            {
            if(!ctx->engine_id)
                  return 0;
            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. */
            if(vcheck_res < OSSL_DYNAMIC_OLDEST)
                  {
                  /* 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();
      fns.err_fns = ERR_get_implementation();
      fns.ex_data_fns = CRYPTO_get_ex_data_implementation();
      CRYPTO_get_mem_functions(&fns.mem_fns.malloc_cb,
                        &fns.mem_fns.realloc_cb,
                        &fns.mem_fns.free_cb);
      fns.lock_fns.lock_locking_cb = CRYPTO_get_locking_callback();
      fns.lock_fns.lock_add_lock_cb = CRYPTO_get_add_lock_callback();
      fns.lock_fns.dynlock_create_cb = CRYPTO_get_dynlock_create_callback();
      fns.lock_fns.dynlock_lock_cb = CRYPTO_get_dynlock_lock_callback();
      fns.lock_fns.dynlock_destroy_cb = CRYPTO_get_dynlock_destroy_callback();
      /* 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(!ctx->bind_engine(e, ctx->engine_id, &fns))
            {
            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;
      }

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