crypto/engine/eng_dyn.c

   1 /*
   2  * Copyright 2001-2016 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 #include "eng_local.h"
  11 #include "internal/dso.h"
  12 #include <openssl/crypto.h>
  13
  14 /*
  15  * Shared libraries implementing ENGINEs for use by the "dynamic" ENGINE
  16  * loader should implement the hook-up functions with the following
  17  * prototypes.
  18  */
  19
  20 /* Our ENGINE handlers */
  21 static int dynamic_init(ENGINE *e);
  22 static int dynamic_finish(ENGINE *e);
  23 static int dynamic_ctrl(ENGINE *e, int cmd, long i, void *p,
  24                         void (*f) (void));
  25 /* Predeclare our context type */
  26 typedef struct st_dynamic_data_ctx dynamic_data_ctx;
  27 /* The implementation for the important control command */
  28 static int dynamic_load(ENGINE *e, dynamic_data_ctx *ctx);
  29
  30 #define DYNAMIC_CMD_SO_PATH             ENGINE_CMD_BASE
  31 #define DYNAMIC_CMD_NO_VCHECK           (ENGINE_CMD_BASE + 1)
  32 #define DYNAMIC_CMD_ID                  (ENGINE_CMD_BASE + 2)
  33 #define DYNAMIC_CMD_LIST_ADD            (ENGINE_CMD_BASE + 3)
  34 #define DYNAMIC_CMD_DIR_LOAD            (ENGINE_CMD_BASE + 4)
  35 #define DYNAMIC_CMD_DIR_ADD             (ENGINE_CMD_BASE + 5)
  36 #define DYNAMIC_CMD_LOAD                (ENGINE_CMD_BASE + 6)
  37
  38 /* The constants used when creating the ENGINE */
  39 static const char *engine_dynamic_id = "dynamic";
  40 static const char *engine_dynamic_name = "Dynamic engine loading support";
  41 static const ENGINE_CMD_DEFN dynamic_cmd_defns[] = {
  42     {DYNAMIC_CMD_SO_PATH,
  43      "SO_PATH",
  44      "Specifies the path to the new ENGINE shared library",
  45      ENGINE_CMD_FLAG_STRING},
  46     {DYNAMIC_CMD_NO_VCHECK,
  47      "NO_VCHECK",
  48      "Specifies to continue even if version checking fails (boolean)",
  49      ENGINE_CMD_FLAG_NUMERIC},
  50     {DYNAMIC_CMD_ID,
  51      "ID",
  52      "Specifies an ENGINE id name for loading",
  53      ENGINE_CMD_FLAG_STRING},
  54     {DYNAMIC_CMD_LIST_ADD,
  55      "LIST_ADD",
  56      "Whether to add a loaded ENGINE to the internal list (0=no,1=yes,2=mandatory)",
  57      ENGINE_CMD_FLAG_NUMERIC},
  58     {DYNAMIC_CMD_DIR_LOAD,
  59      "DIR_LOAD",
  60      "Specifies whether to load from 'DIR_ADD' directories (0=no,1=yes,2=mandatory)",
  61      ENGINE_CMD_FLAG_NUMERIC},
  62     {DYNAMIC_CMD_DIR_ADD,
  63      "DIR_ADD",
  64      "Adds a directory from which ENGINEs can be loaded",
  65      ENGINE_CMD_FLAG_STRING},
  66     {DYNAMIC_CMD_LOAD,
  67      "LOAD",
  68      "Load up the ENGINE specified by other settings",
  69      ENGINE_CMD_FLAG_NO_INPUT},
  70     {0, NULL, NULL, 0}
  71 };
  72
  73 /*
  74  * Loading code stores state inside the ENGINE structure via the "ex_data"
  75  * element. We load all our state into a single structure and use that as a
  76  * single context in the "ex_data" stack.
  77  */
  78 struct st_dynamic_data_ctx {
  79     /* The DSO object we load that supplies the ENGINE code */
  80     DSO *dynamic_dso;
  81     /*
  82      * The function pointer to the version checking shared library function
  83      */
  84     dynamic_v_check_fn v_check;
  85     /*
  86      * The function pointer to the engine-binding shared library function
  87      */
  88     dynamic_bind_engine bind_engine;
  89     /* The default name/path for loading the shared library */
  90     char *DYNAMIC_LIBNAME;
  91     /* Whether to continue loading on a version check failure */
  92     int no_vcheck;
  93     /* If non-NULL, stipulates the 'id' of the ENGINE to be loaded */
  94     char *engine_id;
  95     /*
  96      * If non-zero, a successfully loaded ENGINE should be added to the
  97      * internal ENGINE list. If 2, the add must succeed or the entire load
  98      * should fail.
  99      */
 100     int list_add_value;
 101     /* The symbol name for the version checking function */
 102     const char *DYNAMIC_F1;
 103     /* The symbol name for the "initialise ENGINE structure" function */
 104     const char *DYNAMIC_F2;
 105     /*
 106      * Whether to never use 'dirs', use 'dirs' as a fallback, or only use
 107      * 'dirs' for loading. Default is to use 'dirs' as a fallback.
 108      */
 109     int dir_load;
 110     /* A stack of directories from which ENGINEs could be loaded */
 111     STACK_OF(OPENSSL_STRING) *dirs;
 112 };
 113
 114 /*
 115  * This is the "ex_data" index we obtain and reserve for use with our context
 116  * structure.
 117  */
 118 static int dynamic_ex_data_idx = -1;
 119
 120 static void int_free_str(char *s)
 121 {
 122     OPENSSL_free(s);
 123 }
 124
 125 /*
 126  * Because our ex_data element may or may not get allocated depending on
 127  * whether a "first-use" occurs before the ENGINE is freed, we have a memory
 128  * leak problem to solve. We can't declare a "new" handler for the ex_data as
 129  * we don't want a dynamic_data_ctx in *all* ENGINE structures of all types
 130  * (this is a bug in the design of CRYPTO_EX_DATA). As such, we just declare
 131  * a "free" handler and that will get called if an ENGINE is being destroyed
 132  * and there was an ex_data element corresponding to our context type.
 133  */
 134 static void dynamic_data_ctx_free_func(void *parent, void *ptr,
 135                                        CRYPTO_EX_DATA *ad, int idx, long argl,
 136                                        void *argp)
 137 {
 138     if (ptr) {
 139         dynamic_data_ctx *ctx = (dynamic_data_ctx *)ptr;
 140         DSO_free(ctx->dynamic_dso);
 141         OPENSSL_free(ctx->DYNAMIC_LIBNAME);
 142         OPENSSL_free(ctx->engine_id);
 143         sk_OPENSSL_STRING_pop_free(ctx->dirs, int_free_str);
 144         OPENSSL_free(ctx);
 145     }
 146 }
 147
 148 /*
 149  * Construct the per-ENGINE context. We create it blindly and then use a lock
 150  * to check for a race - if so, all but one of the threads "racing" will have
 151  * wasted their time. The alternative involves creating everything inside the
 152  * lock which is far worse.
 153  */
 154 static int dynamic_set_data_ctx(ENGINE *e, dynamic_data_ctx **ctx)
 155 {
 156     dynamic_data_ctx *c = OPENSSL_zalloc(sizeof(*c));
 157     int ret = 1;
 158
 159     if (c == NULL) {
 160         ENGINEerr(ENGINE_F_DYNAMIC_SET_DATA_CTX, ERR_R_MALLOC_FAILURE);
 161         return 0;
 162     }
 163     c->dirs = sk_OPENSSL_STRING_new_null();
 164     if (c->dirs == NULL) {
 165         ENGINEerr(ENGINE_F_DYNAMIC_SET_DATA_CTX, ERR_R_MALLOC_FAILURE);
 166         OPENSSL_free(c);
 167         return 0;
 168     }
 169     c->DYNAMIC_F1 = "v_check";
 170     c->DYNAMIC_F2 = "bind_engine";
 171     c->dir_load = 1;
 172     CRYPTO_THREAD_write_lock(global_engine_lock);
 173     if ((*ctx = (dynamic_data_ctx *)ENGINE_get_ex_data(e,
 174                                                        dynamic_ex_data_idx))
 175         == NULL) {
 176         /* Good, we're the first */
 177         ret = ENGINE_set_ex_data(e, dynamic_ex_data_idx, c);
 178         if (ret) {
 179             *ctx = c;
 180             c = NULL;
 181         }
 182     }
 183     CRYPTO_THREAD_unlock(global_engine_lock);
 184     /*
 185      * If we lost the race to set the context, c is non-NULL and *ctx is the
 186      * context of the thread that won.
 187      */
 188     if (c)
 189         sk_OPENSSL_STRING_free(c->dirs);
 190     OPENSSL_free(c);
 191     return ret;
 192 }
 193
 194 /*
 195  * This function retrieves the context structure from an ENGINE's "ex_data",
 196  * or if it doesn't exist yet, sets it up.
 197  */
 198 static dynamic_data_ctx *dynamic_get_data_ctx(ENGINE *e)
 199 {
 200     dynamic_data_ctx *ctx;
 201     if (dynamic_ex_data_idx < 0) {
 202         /*
 203          * Create and register the ENGINE ex_data, and associate our "free"
 204          * function with it to ensure any allocated contexts get freed when
 205          * an ENGINE goes underground.
 206          */
 207         int new_idx = ENGINE_get_ex_new_index(0, NULL, NULL, NULL,
 208                                               dynamic_data_ctx_free_func);
 209         if (new_idx == -1) {
 210             ENGINEerr(ENGINE_F_DYNAMIC_GET_DATA_CTX, ENGINE_R_NO_INDEX);
 211             return NULL;
 212         }
 213         CRYPTO_THREAD_write_lock(global_engine_lock);
 214         /* Avoid a race by checking again inside this lock */
 215         if (dynamic_ex_data_idx < 0) {
 216             /* Good, someone didn't beat us to it */
 217             dynamic_ex_data_idx = new_idx;
 218             new_idx = -1;
 219         }
 220         CRYPTO_THREAD_unlock(global_engine_lock);
 221         /*
 222          * In theory we could "give back" the index here if (new_idx>-1), but
 223          * it's not possible and wouldn't gain us much if it were.
 224          */
 225     }
 226     ctx = (dynamic_data_ctx *)ENGINE_get_ex_data(e, dynamic_ex_data_idx);
 227     /* Check if the context needs to be created */
 228     if ((ctx == NULL) && !dynamic_set_data_ctx(e, &ctx))
 229         /* "set_data" will set errors if necessary */
 230         return NULL;
 231     return ctx;
 232 }
 233
 234 static ENGINE *engine_dynamic(void)
 235 {
 236     ENGINE *ret = ENGINE_new();
 237     if (ret == NULL)
 238         return NULL;
 239     if (!ENGINE_set_id(ret, engine_dynamic_id) ||
 240         !ENGINE_set_name(ret, engine_dynamic_name) ||
 241         !ENGINE_set_init_function(ret, dynamic_init) ||
 242         !ENGINE_set_finish_function(ret, dynamic_finish) ||
 243         !ENGINE_set_ctrl_function(ret, dynamic_ctrl) ||
 244         !ENGINE_set_flags(ret, ENGINE_FLAGS_BY_ID_COPY) ||
 245         !ENGINE_set_cmd_defns(ret, dynamic_cmd_defns)) {
 246         ENGINE_free(ret);
 247         return NULL;
 248     }
 249     return ret;
 250 }
 251
 252 void engine_load_dynamic_int(void)
 253 {
 254     ENGINE *toadd = engine_dynamic();
 255     if (!toadd)
 256         return;
 257     ENGINE_add(toadd);
 258     /*
 259      * If the "add" worked, it gets a structural reference. So either way, we
 260      * release our just-created reference.
 261      */
 262     ENGINE_free(toadd);
 263     /*
 264      * If the "add" didn't work, it was probably a conflict because it was
 265      * already added (eg. someone calling ENGINE_load_blah then calling
 266      * ENGINE_load_builtin_engines() perhaps).
 267      */
 268     ERR_clear_error();
 269 }
 270
 271 static int dynamic_init(ENGINE *e)
 272 {
 273     /*
 274      * We always return failure - the "dynamic" engine itself can't be used
 275      * for anything.
 276      */
 277     return 0;
 278 }
 279
 280 static int dynamic_finish(ENGINE *e)
 281 {
 282     /*
 283      * This should never be called on account of "dynamic_init" always
 284      * failing.
 285      */
 286     return 0;
 287 }
 288
 289 static int dynamic_ctrl(ENGINE *e, int cmd, long i, void *p, void (*f) (void))
 290 {
 291     dynamic_data_ctx *ctx = dynamic_get_data_ctx(e);
 292     int initialised;
 293
 294     if (!ctx) {
 295         ENGINEerr(ENGINE_F_DYNAMIC_CTRL, ENGINE_R_NOT_LOADED);
 296         return 0;
 297     }
 298     initialised = ((ctx->dynamic_dso == NULL) ? 0 : 1);
 299     /* All our control commands require the ENGINE to be uninitialised */
 300     if (initialised) {
 301         ENGINEerr(ENGINE_F_DYNAMIC_CTRL, ENGINE_R_ALREADY_LOADED);
 302         return 0;
 303     }
 304     switch (cmd) {
 305     case DYNAMIC_CMD_SO_PATH:
 306         /* a NULL 'p' or a string of zero-length is the same thing */
 307         if (p && (strlen((const char *)p) < 1))
 308             p = NULL;
 309         OPENSSL_free(ctx->DYNAMIC_LIBNAME);
 310         if (p)
 311             ctx->DYNAMIC_LIBNAME = OPENSSL_strdup(p);
 312         else
 313             ctx->DYNAMIC_LIBNAME = NULL;
 314         return (ctx->DYNAMIC_LIBNAME ? 1 : 0);
 315     case DYNAMIC_CMD_NO_VCHECK:
 316         ctx->no_vcheck = ((i == 0) ? 0 : 1);
 317         return 1;
 318     case DYNAMIC_CMD_ID:
 319         /* a NULL 'p' or a string of zero-length is the same thing */
 320         if (p && (strlen((const char *)p) < 1))
 321             p = NULL;
 322         OPENSSL_free(ctx->engine_id);
 323         if (p)
 324             ctx->engine_id = OPENSSL_strdup(p);
 325         else
 326             ctx->engine_id = NULL;
 327         return (ctx->engine_id ? 1 : 0);
 328     case DYNAMIC_CMD_LIST_ADD:
 329         if ((i < 0) || (i > 2)) {
 330             ENGINEerr(ENGINE_F_DYNAMIC_CTRL, ENGINE_R_INVALID_ARGUMENT);
 331             return 0;
 332         }
 333         ctx->list_add_value = (int)i;
 334         return 1;
 335     case DYNAMIC_CMD_LOAD:
 336         return dynamic_load(e, ctx);
 337     case DYNAMIC_CMD_DIR_LOAD:
 338         if ((i < 0) || (i > 2)) {
 339             ENGINEerr(ENGINE_F_DYNAMIC_CTRL, ENGINE_R_INVALID_ARGUMENT);
 340             return 0;
 341         }
 342         ctx->dir_load = (int)i;
 343         return 1;
 344     case DYNAMIC_CMD_DIR_ADD:
 345         /* a NULL 'p' or a string of zero-length is the same thing */
 346         if (!p || (strlen((const char *)p) < 1)) {
 347             ENGINEerr(ENGINE_F_DYNAMIC_CTRL, ENGINE_R_INVALID_ARGUMENT);
 348             return 0;
 349         }
 350         {
 351             char *tmp_str = OPENSSL_strdup(p);
 352             if (tmp_str == NULL) {
 353                 ENGINEerr(ENGINE_F_DYNAMIC_CTRL, ERR_R_MALLOC_FAILURE);
 354                 return 0;
 355             }
 356             if (!sk_OPENSSL_STRING_push(ctx->dirs, tmp_str)) {
 357                 OPENSSL_free(tmp_str);
 358                 ENGINEerr(ENGINE_F_DYNAMIC_CTRL, ERR_R_MALLOC_FAILURE);
 359                 return 0;
 360             }
 361         }
 362         return 1;
 363     default:
 364         break;
 365     }
 366     ENGINEerr(ENGINE_F_DYNAMIC_CTRL, ENGINE_R_CTRL_COMMAND_NOT_IMPLEMENTED);
 367     return 0;
 368 }
 369
 370 static int int_load(dynamic_data_ctx *ctx)
 371 {
 372     int num, loop;
 373     /* Unless told not to, try a direct load */
 374     if ((ctx->dir_load != 2) && (DSO_load(ctx->dynamic_dso,
 375                                           ctx->DYNAMIC_LIBNAME, NULL,
 376                                           0)) != NULL)
 377         return 1;
 378     /* If we're not allowed to use 'dirs' or we have none, fail */
 379     if (!ctx->dir_load || (num = sk_OPENSSL_STRING_num(ctx->dirs)) < 1)
 380         return 0;
 381     for (loop = 0; loop < num; loop++) {
 382         const char *s = sk_OPENSSL_STRING_value(ctx->dirs, loop);
 383         char *merge = DSO_merge(ctx->dynamic_dso, ctx->DYNAMIC_LIBNAME, s);
 384         if (!merge)
 385             return 0;
 386         if (DSO_load(ctx->dynamic_dso, merge, NULL, 0)) {
 387             /* Found what we're looking for */
 388             OPENSSL_free(merge);
 389             return 1;
 390         }
 391         OPENSSL_free(merge);
 392     }
 393     return 0;
 394 }
 395
 396 static int dynamic_load(ENGINE *e, dynamic_data_ctx *ctx)
 397 {
 398     ENGINE cpy;
 399     dynamic_fns fns;
 400
 401     if (ctx->dynamic_dso == NULL)
 402         ctx->dynamic_dso = DSO_new();
 403     if (ctx->dynamic_dso == NULL)
 404         return 0;
 405     if (!ctx->DYNAMIC_LIBNAME) {
 406         if (!ctx->engine_id)
 407             return 0;
 408         DSO_ctrl(ctx->dynamic_dso, DSO_CTRL_SET_FLAGS,
 409                  DSO_FLAG_NAME_TRANSLATION_EXT_ONLY, NULL);
 410         ctx->DYNAMIC_LIBNAME =
 411             DSO_convert_filename(ctx->dynamic_dso, ctx->engine_id);
 412     }
 413     if (!int_load(ctx)) {
 414         ENGINEerr(ENGINE_F_DYNAMIC_LOAD, ENGINE_R_DSO_NOT_FOUND);
 415         DSO_free(ctx->dynamic_dso);
 416         ctx->dynamic_dso = NULL;
 417         return 0;
 418     }
 419     /* We have to find a bind function otherwise it'll always end badly */
 420     if (!
 421         (ctx->bind_engine =
 422          (dynamic_bind_engine) DSO_bind_func(ctx->dynamic_dso,
 423                                              ctx->DYNAMIC_F2))) {
 424         ctx->bind_engine = NULL;
 425         DSO_free(ctx->dynamic_dso);
 426         ctx->dynamic_dso = NULL;
 427         ENGINEerr(ENGINE_F_DYNAMIC_LOAD, ENGINE_R_DSO_FAILURE);
 428         return 0;
 429     }
 430     /* Do we perform version checking? */
 431     if (!ctx->no_vcheck) {
 432         unsigned long vcheck_res = 0;
 433         /*
 434          * Now we try to find a version checking function and decide how to
 435          * cope with failure if/when it fails.
 436          */
 437         ctx->v_check =
 438             (dynamic_v_check_fn) DSO_bind_func(ctx->dynamic_dso,
 439                                                ctx->DYNAMIC_F1);
 440         if (ctx->v_check)
 441             vcheck_res = ctx->v_check(OSSL_DYNAMIC_VERSION);
 442         /*
 443          * We fail if the version checker veto'd the load *or* if it is
 444          * deferring to us (by returning its version) and we think it is too
 445          * old.
 446          */
 447         if (vcheck_res < OSSL_DYNAMIC_OLDEST) {
 448             /* Fail */
 449             ctx->bind_engine = NULL;
 450             ctx->v_check = NULL;
 451             DSO_free(ctx->dynamic_dso);
 452             ctx->dynamic_dso = NULL;
 453             ENGINEerr(ENGINE_F_DYNAMIC_LOAD,
 454                       ENGINE_R_VERSION_INCOMPATIBILITY);
 455             return 0;
 456         }
 457     }
 458     /*
 459      * First binary copy the ENGINE structure so that we can roll back if the
 460      * hand-over fails
 461      */
 462     memcpy(&cpy, e, sizeof(ENGINE));
 463     /*
 464      * Provide the ERR, "ex_data", memory, and locking callbacks so the
 465      * loaded library uses our state rather than its own. FIXME: As noted in
 466      * engine.h, much of this would be simplified if each area of code
 467      * provided its own "summary" structure of all related callbacks. It
 468      * would also increase opaqueness.
 469      */
 470     fns.static_state = ENGINE_get_static_state();
 471     CRYPTO_get_mem_functions(&fns.mem_fns.malloc_fn, &fns.mem_fns.realloc_fn,
 472                              &fns.mem_fns.free_fn);
 473     /*
 474      * Now that we've loaded the dynamic engine, make sure no "dynamic"
 475      * ENGINE elements will show through.
 476      */
 477     engine_set_all_null(e);
 478
 479     /* Try to bind the ENGINE onto our own ENGINE structure */
 480     if (!ctx->bind_engine(e, ctx->engine_id, &fns)) {
 481         ctx->bind_engine = NULL;
 482         ctx->v_check = NULL;
 483         DSO_free(ctx->dynamic_dso);
 484         ctx->dynamic_dso = NULL;
 485         ENGINEerr(ENGINE_F_DYNAMIC_LOAD, ENGINE_R_INIT_FAILED);
 486         /* Copy the original ENGINE structure back */
 487         memcpy(e, &cpy, sizeof(ENGINE));
 488         return 0;
 489     }
 490     /* Do we try to add this ENGINE to the internal list too? */
 491     if (ctx->list_add_value > 0) {
 492         if (!ENGINE_add(e)) {
 493             /* Do we tolerate this or fail? */
 494             if (ctx->list_add_value > 1) {
 495                 /*
 496                  * Fail - NB: By this time, it's too late to rollback, and
 497                  * trying to do so allows the bind_engine() code to have
 498                  * created leaks. We just have to fail where we are, after
 499                  * the ENGINE has changed.
 500                  */
 501                 ENGINEerr(ENGINE_F_DYNAMIC_LOAD,
 502                           ENGINE_R_CONFLICTING_ENGINE_ID);
 503                 return 0;
 504             }
 505             /* Tolerate */
 506             ERR_clear_error();
 507         }
 508     }
 509     return 1;
 510 }