crypto/engine/eng_dyn.c

   1 /*
   2  * Copyright 2001-2021 The OpenSSL Project Authors. All Rights Reserved.
   3  *
   4  * Licensed under the Apache License 2.0 (the "License").  You may not use
   5  * this file except in compliance with the License.  You can obtain a copy
   6  * in the file LICENSE in the source distribution or at
   7  * https://www.openssl.org/source/license.html
   8  */
   9
  10 /* We need to use some engine deprecated APIs */
  11 #define OPENSSL_SUPPRESS_DEPRECATED
  12
  13 #include "eng_local.h"
  14 #include "internal/dso.h"
  15 #include <openssl/crypto.h>
  16
  17 /*
  18  * Shared libraries implementing ENGINEs for use by the "dynamic" ENGINE
  19  * loader should implement the hook-up functions with the following
  20  * prototypes.
  21  */
  22
  23 /* Our ENGINE handlers */
  24 static int dynamic_init(ENGINE *e);
  25 static int dynamic_finish(ENGINE *e);
  26 static int dynamic_ctrl(ENGINE *e, int cmd, long i, void *p,
  27                         void (*f) (void));
  28 /* Predeclare our context type */
  29 typedef struct st_dynamic_data_ctx dynamic_data_ctx;
  30 /* The implementation for the important control command */
  31 static int dynamic_load(ENGINE *e, dynamic_data_ctx *ctx);
  32
  33 #define DYNAMIC_CMD_SO_PATH             ENGINE_CMD_BASE
  34 #define DYNAMIC_CMD_NO_VCHECK           (ENGINE_CMD_BASE + 1)
  35 #define DYNAMIC_CMD_ID                  (ENGINE_CMD_BASE + 2)
  36 #define DYNAMIC_CMD_LIST_ADD            (ENGINE_CMD_BASE + 3)
  37 #define DYNAMIC_CMD_DIR_LOAD            (ENGINE_CMD_BASE + 4)
  38 #define DYNAMIC_CMD_DIR_ADD             (ENGINE_CMD_BASE + 5)
  39 #define DYNAMIC_CMD_LOAD                (ENGINE_CMD_BASE + 6)
  40
  41 /* The constants used when creating the ENGINE */
  42 static const char *engine_dynamic_id = "dynamic";
  43 static const char *engine_dynamic_name = "Dynamic engine loading support";
  44 static const ENGINE_CMD_DEFN dynamic_cmd_defns[] = {
  45     {DYNAMIC_CMD_SO_PATH,
  46      "SO_PATH",
  47      "Specifies the path to the new ENGINE shared library",
  48      ENGINE_CMD_FLAG_STRING},
  49     {DYNAMIC_CMD_NO_VCHECK,
  50      "NO_VCHECK",
  51      "Specifies to continue even if version checking fails (boolean)",
  52      ENGINE_CMD_FLAG_NUMERIC},
  53     {DYNAMIC_CMD_ID,
  54      "ID",
  55      "Specifies an ENGINE id name for loading",
  56      ENGINE_CMD_FLAG_STRING},
  57     {DYNAMIC_CMD_LIST_ADD,
  58      "LIST_ADD",
  59      "Whether to add a loaded ENGINE to the internal list (0=no,1=yes,2=mandatory)",
  60      ENGINE_CMD_FLAG_NUMERIC},
  61     {DYNAMIC_CMD_DIR_LOAD,
  62      "DIR_LOAD",
  63      "Specifies whether to load from 'DIR_ADD' directories (0=no,1=yes,2=mandatory)",
  64      ENGINE_CMD_FLAG_NUMERIC},
  65     {DYNAMIC_CMD_DIR_ADD,
  66      "DIR_ADD",
  67      "Adds a directory from which ENGINEs can be loaded",
  68      ENGINE_CMD_FLAG_STRING},
  69     {DYNAMIC_CMD_LOAD,
  70      "LOAD",
  71      "Load up the ENGINE specified by other settings",
  72      ENGINE_CMD_FLAG_NO_INPUT},
  73     {0, NULL, NULL, 0}
  74 };
  75
  76 /*
  77  * Loading code stores state inside the ENGINE structure via the "ex_data"
  78  * element. We load all our state into a single structure and use that as a
  79  * single context in the "ex_data" stack.
  80  */
  81 struct st_dynamic_data_ctx {
  82     /* The DSO object we load that supplies the ENGINE code */
  83     DSO *dynamic_dso;
  84     /*
  85      * The function pointer to the version checking shared library function
  86      */
  87     dynamic_v_check_fn v_check;
  88     /*
  89      * The function pointer to the engine-binding shared library function
  90      */
  91     dynamic_bind_engine bind_engine;
  92     /* The default name/path for loading the shared library */
  93     char *DYNAMIC_LIBNAME;
  94     /* Whether to continue loading on a version check failure */
  95     int no_vcheck;
  96     /* If non-NULL, stipulates the 'id' of the ENGINE to be loaded */
  97     char *engine_id;
  98     /*
  99      * If non-zero, a successfully loaded ENGINE should be added to the
 100      * internal ENGINE list. If 2, the add must succeed or the entire load
 101      * should fail.
 102      */
 103     int list_add_value;
 104     /* The symbol name for the version checking function */
 105     const char *DYNAMIC_F1;
 106     /* The symbol name for the "initialise ENGINE structure" function */
 107     const char *DYNAMIC_F2;
 108     /*
 109      * Whether to never use 'dirs', use 'dirs' as a fallback, or only use
 110      * 'dirs' for loading. Default is to use 'dirs' as a fallback.
 111      */
 112     int dir_load;
 113     /* A stack of directories from which ENGINEs could be loaded */
 114     STACK_OF(OPENSSL_STRING) *dirs;
 115 };
 116
 117 /*
 118  * This is the "ex_data" index we obtain and reserve for use with our context
 119  * structure.
 120  */
 121 static int dynamic_ex_data_idx = -1;
 122
 123 static void int_free_str(char *s)
 124 {
 125     OPENSSL_free(s);
 126 }
 127
 128 /*
 129  * Because our ex_data element may or may not get allocated depending on
 130  * whether a "first-use" occurs before the ENGINE is freed, we have a memory
 131  * leak problem to solve. We can't declare a "new" handler for the ex_data as
 132  * we don't want a dynamic_data_ctx in *all* ENGINE structures of all types
 133  * (this is a bug in the design of CRYPTO_EX_DATA). As such, we just declare
 134  * a "free" handler and that will get called if an ENGINE is being destroyed
 135  * and there was an ex_data element corresponding to our context type.
 136  */
 137 static void dynamic_data_ctx_free_func(void *parent, void *ptr,
 138                                        CRYPTO_EX_DATA *ad, int idx, long argl,
 139                                        void *argp)
 140 {
 141     if (ptr) {
 142         dynamic_data_ctx *ctx = (dynamic_data_ctx *)ptr;
 143         DSO_free(ctx->dynamic_dso);
 144         OPENSSL_free(ctx->DYNAMIC_LIBNAME);
 145         OPENSSL_free(ctx->engine_id);
 146         sk_OPENSSL_STRING_pop_free(ctx->dirs, int_free_str);
 147         OPENSSL_free(ctx);
 148     }
 149 }
 150
 151 /*
 152  * Construct the per-ENGINE context. We create it blindly and then use a lock
 153  * to check for a race - if so, all but one of the threads "racing" will have
 154  * wasted their time. The alternative involves creating everything inside the
 155  * lock which is far worse.
 156  */
 157 static int dynamic_set_data_ctx(ENGINE *e, dynamic_data_ctx **ctx)
 158 {
 159     dynamic_data_ctx *c = OPENSSL_zalloc(sizeof(*c));
 160     int ret = 0;
 161
 162     if (c == NULL) {
 163         ERR_raise(ERR_LIB_ENGINE, ERR_R_MALLOC_FAILURE);
 164         return 0;
 165     }
 166     c->dirs = sk_OPENSSL_STRING_new_null();
 167     if (c->dirs == NULL) {
 168         ERR_raise(ERR_LIB_ENGINE, ERR_R_MALLOC_FAILURE);
 169         goto end;
 170     }
 171     c->DYNAMIC_F1 = "v_check";
 172     c->DYNAMIC_F2 = "bind_engine";
 173     c->dir_load = 1;
 174     if (!CRYPTO_THREAD_write_lock(global_engine_lock))
 175         goto end;
 176     if ((*ctx = (dynamic_data_ctx *)ENGINE_get_ex_data(e,
 177                                                        dynamic_ex_data_idx))
 178         == NULL) {
 179         /* Good, we're the first */
 180         ret = ENGINE_set_ex_data(e, dynamic_ex_data_idx, c);
 181         if (ret) {
 182             *ctx = c;
 183             c = NULL;
 184         }
 185     }
 186     CRYPTO_THREAD_unlock(global_engine_lock);
 187     ret = 1;
 188     /*
 189      * If we lost the race to set the context, c is non-NULL and *ctx is the
 190      * context of the thread that won.
 191      */
 192 end:
 193     if (c != NULL)
 194         sk_OPENSSL_STRING_free(c->dirs);
 195     OPENSSL_free(c);
 196     return ret;
 197 }
 198
 199 /*
 200  * This function retrieves the context structure from an ENGINE's "ex_data",
 201  * or if it doesn't exist yet, sets it up.
 202  */
 203 static dynamic_data_ctx *dynamic_get_data_ctx(ENGINE *e)
 204 {
 205     dynamic_data_ctx *ctx;
 206     if (dynamic_ex_data_idx < 0) {
 207         /*
 208          * Create and register the ENGINE ex_data, and associate our "free"
 209          * function with it to ensure any allocated contexts get freed when
 210          * an ENGINE goes underground.
 211          */
 212         int new_idx = ENGINE_get_ex_new_index(0, NULL, NULL, NULL,
 213                                               dynamic_data_ctx_free_func);
 214         if (new_idx == -1) {
 215             ERR_raise(ERR_LIB_ENGINE, ENGINE_R_NO_INDEX);
 216             return NULL;
 217         }
 218         if (!CRYPTO_THREAD_write_lock(global_engine_lock))
 219             return NULL;
 220         /* Avoid a race by checking again inside this lock */
 221         if (dynamic_ex_data_idx < 0) {
 222             /* Good, someone didn't beat us to it */
 223             dynamic_ex_data_idx = new_idx;
 224             new_idx = -1;
 225         }
 226         CRYPTO_THREAD_unlock(global_engine_lock);
 227         /*
 228          * In theory we could "give back" the index here if (new_idx>-1), but
 229          * it's not possible and wouldn't gain us much if it were.
 230          */
 231     }
 232     ctx = (dynamic_data_ctx *)ENGINE_get_ex_data(e, dynamic_ex_data_idx);
 233     /* Check if the context needs to be created */
 234     if ((ctx == NULL) && !dynamic_set_data_ctx(e, &ctx))
 235         /* "set_data" will set errors if necessary */
 236         return NULL;
 237     return ctx;
 238 }
 239
 240 static ENGINE *engine_dynamic(void)
 241 {
 242     ENGINE *ret = ENGINE_new();
 243     if (ret == NULL)
 244         return NULL;
 245     if (!ENGINE_set_id(ret, engine_dynamic_id) ||
 246         !ENGINE_set_name(ret, engine_dynamic_name) ||
 247         !ENGINE_set_init_function(ret, dynamic_init) ||
 248         !ENGINE_set_finish_function(ret, dynamic_finish) ||
 249         !ENGINE_set_ctrl_function(ret, dynamic_ctrl) ||
 250         !ENGINE_set_flags(ret, ENGINE_FLAGS_BY_ID_COPY) ||
 251         !ENGINE_set_cmd_defns(ret, dynamic_cmd_defns)) {
 252         ENGINE_free(ret);
 253         return NULL;
 254     }
 255     return ret;
 256 }
 257
 258 void engine_load_dynamic_int(void)
 259 {
 260     ENGINE *toadd = engine_dynamic();
 261     if (!toadd)
 262         return;
 263
 264     ERR_set_mark();
 265     ENGINE_add(toadd);
 266     /*
 267      * If the "add" worked, it gets a structural reference. So either way, we
 268      * release our just-created reference.
 269      */
 270     ENGINE_free(toadd);
 271     /*
 272      * If the "add" didn't work, it was probably a conflict because it was
 273      * already added (eg. someone calling ENGINE_load_blah then calling
 274      * ENGINE_load_builtin_engines() perhaps).
 275      */
 276     ERR_pop_to_mark();
 277 }
 278
 279 static int dynamic_init(ENGINE *e)
 280 {
 281     /*
 282      * We always return failure - the "dynamic" engine itself can't be used
 283      * for anything.
 284      */
 285     return 0;
 286 }
 287
 288 static int dynamic_finish(ENGINE *e)
 289 {
 290     /*
 291      * This should never be called on account of "dynamic_init" always
 292      * failing.
 293      */
 294     return 0;
 295 }
 296
 297 static int dynamic_ctrl(ENGINE *e, int cmd, long i, void *p, void (*f) (void))
 298 {
 299     dynamic_data_ctx *ctx = dynamic_get_data_ctx(e);
 300     int initialised;
 301
 302     if (!ctx) {
 303         ERR_raise(ERR_LIB_ENGINE, ENGINE_R_NOT_LOADED);
 304         return 0;
 305     }
 306     initialised = ((ctx->dynamic_dso == NULL) ? 0 : 1);
 307     /* All our control commands require the ENGINE to be uninitialised */
 308     if (initialised) {
 309         ERR_raise(ERR_LIB_ENGINE, ENGINE_R_ALREADY_LOADED);
 310         return 0;
 311     }
 312     switch (cmd) {
 313     case DYNAMIC_CMD_SO_PATH:
 314         /* a NULL 'p' or a string of zero-length is the same thing */
 315         if (p && (strlen((const char *)p) < 1))
 316             p = NULL;
 317         OPENSSL_free(ctx->DYNAMIC_LIBNAME);
 318         if (p)
 319             ctx->DYNAMIC_LIBNAME = OPENSSL_strdup(p);
 320         else
 321             ctx->DYNAMIC_LIBNAME = NULL;
 322         return (ctx->DYNAMIC_LIBNAME ? 1 : 0);
 323     case DYNAMIC_CMD_NO_VCHECK:
 324         ctx->no_vcheck = ((i == 0) ? 0 : 1);
 325         return 1;
 326     case DYNAMIC_CMD_ID:
 327         /* a NULL 'p' or a string of zero-length is the same thing */
 328         if (p && (strlen((const char *)p) < 1))
 329             p = NULL;
 330         OPENSSL_free(ctx->engine_id);
 331         if (p)
 332             ctx->engine_id = OPENSSL_strdup(p);
 333         else
 334             ctx->engine_id = NULL;
 335         return (ctx->engine_id ? 1 : 0);
 336     case DYNAMIC_CMD_LIST_ADD:
 337         if ((i < 0) || (i > 2)) {
 338             ERR_raise(ERR_LIB_ENGINE, ENGINE_R_INVALID_ARGUMENT);
 339             return 0;
 340         }
 341         ctx->list_add_value = (int)i;
 342         return 1;
 343     case DYNAMIC_CMD_LOAD:
 344         return dynamic_load(e, ctx);
 345     case DYNAMIC_CMD_DIR_LOAD:
 346         if ((i < 0) || (i > 2)) {
 347             ERR_raise(ERR_LIB_ENGINE, ENGINE_R_INVALID_ARGUMENT);
 348             return 0;
 349         }
 350         ctx->dir_load = (int)i;
 351         return 1;
 352     case DYNAMIC_CMD_DIR_ADD:
 353         /* a NULL 'p' or a string of zero-length is the same thing */
 354         if (p == NULL || (strlen((const char *)p) < 1)) {
 355             ERR_raise(ERR_LIB_ENGINE, ENGINE_R_INVALID_ARGUMENT);
 356             return 0;
 357         }
 358         {
 359             char *tmp_str = OPENSSL_strdup(p);
 360             if (tmp_str == NULL) {
 361                 ERR_raise(ERR_LIB_ENGINE, ERR_R_MALLOC_FAILURE);
 362                 return 0;
 363             }
 364             if (!sk_OPENSSL_STRING_push(ctx->dirs, tmp_str)) {
 365                 OPENSSL_free(tmp_str);
 366                 ERR_raise(ERR_LIB_ENGINE, ERR_R_MALLOC_FAILURE);
 367                 return 0;
 368             }
 369         }
 370         return 1;
 371     default:
 372         break;
 373     }
 374     ERR_raise(ERR_LIB_ENGINE, ENGINE_R_CTRL_COMMAND_NOT_IMPLEMENTED);
 375     return 0;
 376 }
 377
 378 static int int_load(dynamic_data_ctx *ctx)
 379 {
 380     int num, loop;
 381     /* Unless told not to, try a direct load */
 382     if ((ctx->dir_load != 2) && (DSO_load(ctx->dynamic_dso,
 383                                           ctx->DYNAMIC_LIBNAME, NULL,
 384                                           0)) != NULL)
 385         return 1;
 386     /* If we're not allowed to use 'dirs' or we have none, fail */
 387     if (!ctx->dir_load || (num = sk_OPENSSL_STRING_num(ctx->dirs)) < 1)
 388         return 0;
 389     for (loop = 0; loop < num; loop++) {
 390         const char *s = sk_OPENSSL_STRING_value(ctx->dirs, loop);
 391         char *merge = DSO_merge(ctx->dynamic_dso, ctx->DYNAMIC_LIBNAME, s);
 392         if (!merge)
 393             return 0;
 394         if (DSO_load(ctx->dynamic_dso, merge, NULL, 0)) {
 395             /* Found what we're looking for */
 396             OPENSSL_free(merge);
 397             return 1;
 398         }
 399         OPENSSL_free(merge);
 400     }
 401     return 0;
 402 }
 403
 404 static int dynamic_load(ENGINE *e, dynamic_data_ctx *ctx)
 405 {
 406     ENGINE cpy;
 407     dynamic_fns fns;
 408
 409     if (ctx->dynamic_dso == NULL)
 410         ctx->dynamic_dso = DSO_new();
 411     if (ctx->dynamic_dso == NULL)
 412         return 0;
 413     if (!ctx->DYNAMIC_LIBNAME) {
 414         if (!ctx->engine_id)
 415             return 0;
 416         DSO_ctrl(ctx->dynamic_dso, DSO_CTRL_SET_FLAGS,
 417                  DSO_FLAG_NAME_TRANSLATION_EXT_ONLY, NULL);
 418         ctx->DYNAMIC_LIBNAME =
 419             DSO_convert_filename(ctx->dynamic_dso, ctx->engine_id);
 420     }
 421     if (!int_load(ctx)) {
 422         ERR_raise(ERR_LIB_ENGINE, ENGINE_R_DSO_NOT_FOUND);
 423         DSO_free(ctx->dynamic_dso);
 424         ctx->dynamic_dso = NULL;
 425         return 0;
 426     }
 427     /* We have to find a bind function otherwise it'll always end badly */
 428     if (!
 429         (ctx->bind_engine =
 430          (dynamic_bind_engine) DSO_bind_func(ctx->dynamic_dso,
 431                                              ctx->DYNAMIC_F2))) {
 432         ctx->bind_engine = NULL;
 433         DSO_free(ctx->dynamic_dso);
 434         ctx->dynamic_dso = NULL;
 435         ERR_raise(ERR_LIB_ENGINE, ENGINE_R_DSO_FAILURE);
 436         return 0;
 437     }
 438     /* Do we perform version checking? */
 439     if (!ctx->no_vcheck) {
 440         unsigned long vcheck_res = 0;
 441         /*
 442          * Now we try to find a version checking function and decide how to
 443          * cope with failure if/when it fails.
 444          */
 445         ctx->v_check =
 446             (dynamic_v_check_fn) DSO_bind_func(ctx->dynamic_dso,
 447                                                ctx->DYNAMIC_F1);
 448         if (ctx->v_check)
 449             vcheck_res = ctx->v_check(OSSL_DYNAMIC_VERSION);
 450         /*
 451          * We fail if the version checker veto'd the load *or* if it is
 452          * deferring to us (by returning its version) and we think it is too
 453          * old.
 454          */
 455         if (vcheck_res < OSSL_DYNAMIC_OLDEST) {
 456             /* Fail */
 457             ctx->bind_engine = NULL;
 458             ctx->v_check = NULL;
 459             DSO_free(ctx->dynamic_dso);
 460             ctx->dynamic_dso = NULL;
 461             ERR_raise(ERR_LIB_ENGINE, ENGINE_R_VERSION_INCOMPATIBILITY);
 462             return 0;
 463         }
 464     }
 465     /*
 466      * First binary copy the ENGINE structure so that we can roll back if the
 467      * hand-over fails
 468      */
 469     memcpy(&cpy, e, sizeof(ENGINE));
 470     /*
 471      * Provide the ERR, "ex_data", memory, and locking callbacks so the
 472      * loaded library uses our state rather than its own. FIXME: As noted in
 473      * engine.h, much of this would be simplified if each area of code
 474      * provided its own "summary" structure of all related callbacks. It
 475      * would also increase opaqueness.
 476      */
 477     fns.static_state = ENGINE_get_static_state();
 478     CRYPTO_get_mem_functions(&fns.mem_fns.malloc_fn, &fns.mem_fns.realloc_fn,
 479                              &fns.mem_fns.free_fn);
 480     /*
 481      * Now that we've loaded the dynamic engine, make sure no "dynamic"
 482      * ENGINE elements will show through.
 483      */
 484     engine_set_all_null(e);
 485
 486     /* Try to bind the ENGINE onto our own ENGINE structure */
 487     if (!ctx->bind_engine(e, ctx->engine_id, &fns)) {
 488         ctx->bind_engine = NULL;
 489         ctx->v_check = NULL;
 490         DSO_free(ctx->dynamic_dso);
 491         ctx->dynamic_dso = NULL;
 492         ERR_raise(ERR_LIB_ENGINE, ENGINE_R_INIT_FAILED);
 493         /* Copy the original ENGINE structure back */
 494         memcpy(e, &cpy, sizeof(ENGINE));
 495         return 0;
 496     }
 497     /* Do we try to add this ENGINE to the internal list too? */
 498     if (ctx->list_add_value > 0) {
 499         if (!ENGINE_add(e)) {
 500             /* Do we tolerate this or fail? */
 501             if (ctx->list_add_value > 1) {
 502                 /*
 503                  * Fail - NB: By this time, it's too late to rollback, and
 504                  * trying to do so allows the bind_engine() code to have
 505                  * created leaks. We just have to fail where we are, after
 506                  * the ENGINE has changed.
 507                  */
 508                 ERR_raise(ERR_LIB_ENGINE, ENGINE_R_CONFLICTING_ENGINE_ID);
 509                 return 0;
 510             }
 511             /* Tolerate */
 512             ERR_clear_error();
 513         }
 514     }
 515     return 1;
 516 }