ssh-pkcs11.c

   1 /* $OpenBSD: ssh-pkcs11.c,v 1.4 2010/02/24 06:12:53 djm Exp $ */
   2 /*
   3  * Copyright (c) 2010 Markus Friedl.  All rights reserved.
   4  *
   5  * Permission to use, copy, modify, and distribute this software for any
   6  * purpose with or without fee is hereby granted, provided that the above
   7  * copyright notice and this permission notice appear in all copies.
   8  *
   9  * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
  10  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
  11  * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
  12  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
  13  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
  14  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
  15  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  16  */
  17
  18 #include "includes.h"
  19
  20 #ifdef ENABLE_PKCS11
  21
  22 #include <sys/types.h>
  23 #ifdef HAVE_SYS_TIME_H
  24 # include <sys/time.h>
  25 #endif
  26 #include <stdarg.h>
  27 #include <stdio.h>
  28
  29 #include <string.h>
  30 #include <dlfcn.h>
  31
  32 #include "openbsd-compat/sys-queue.h"
  33
  34 #define CRYPTOKI_COMPAT
  35 #include "pkcs11.h"
  36
  37 #include "log.h"
  38 #include "misc.h"
  39 #include "key.h"
  40 #include "ssh-pkcs11.h"
  41 #include "xmalloc.h"
  42
  43 struct pkcs11_slotinfo {
  44         CK_TOKEN_INFO           token;
  45         CK_SESSION_HANDLE       session;
  46         int                     logged_in;
  47 };
  48
  49 struct pkcs11_provider {
  50         char                    *name;
  51         void                    *handle;
  52         CK_FUNCTION_LIST        *function_list;
  53         CK_INFO                 info;
  54         CK_ULONG                nslots;
  55         CK_SLOT_ID              *slotlist;
  56         struct pkcs11_slotinfo  *slotinfo;
  57         int                     valid;
  58         int                     refcount;
  59         TAILQ_ENTRY(pkcs11_provider) next;
  60 };
  61
  62 TAILQ_HEAD(, pkcs11_provider) pkcs11_providers;
  63
  64 struct pkcs11_key {
  65         struct pkcs11_provider  *provider;
  66         CK_ULONG                slotidx;
  67         int                     (*orig_finish)(RSA *rsa);
  68         RSA_METHOD              rsa_method;
  69         char                    *keyid;
  70         int                     keyid_len;
  71 };
  72
  73 int pkcs11_interactive = 0;
  74
  75 int
  76 pkcs11_init(int interactive)
  77 {
  78         pkcs11_interactive = interactive;
  79         TAILQ_INIT(&pkcs11_providers);
  80         return (0);
  81 }
  82
  83 /*
  84  * finalize a provider shared libarary, it's no longer usable.
  85  * however, there might still be keys referencing this provider,
  86  * so the actuall freeing of memory is handled by pkcs11_provider_unref().
  87  * this is called when a provider gets unregistered.
  88  */
  89 static void
  90 pkcs11_provider_finalize(struct pkcs11_provider *p)
  91 {
  92         CK_RV rv;
  93         CK_ULONG i;
  94
  95         debug("pkcs11_provider_finalize: %p refcount %d valid %d",
  96             p, p->refcount, p->valid);
  97         if (!p->valid)
  98                 return;
  99         for (i = 0; i < p->nslots; i++) {
 100                 if (p->slotinfo[i].session &&
 101                     (rv = p->function_list->C_CloseSession(
 102                     p->slotinfo[i].session)) != CKR_OK)
 103                         error("C_CloseSession failed: %lu", rv);
 104         }
 105         if ((rv = p->function_list->C_Finalize(NULL)) != CKR_OK)
 106                 error("C_Finalize failed: %lu", rv);
 107         p->valid = 0;
 108         p->function_list = NULL;
 109         dlclose(p->handle);
 110 }
 111
 112 /*
 113  * remove a reference to the provider.
 114  * called when a key gets destroyed or when the provider is unregistered.
 115  */
 116 static void
 117 pkcs11_provider_unref(struct pkcs11_provider *p)
 118 {
 119         debug("pkcs11_provider_unref: %p refcount %d", p, p->refcount);
 120         if (--p->refcount <= 0) {
 121                 if (p->valid)
 122                         error("pkcs11_provider_unref: %p still valid", p);
 123                 xfree(p->slotlist);
 124                 xfree(p->slotinfo);
 125                 xfree(p);
 126         }
 127 }
 128
 129 /* unregister all providers, keys might still point to the providers */
 130 void
 131 pkcs11_terminate(void)
 132 {
 133         struct pkcs11_provider *p;
 134
 135         while ((p = TAILQ_FIRST(&pkcs11_providers)) != NULL) {
 136                 TAILQ_REMOVE(&pkcs11_providers, p, next);
 137                 pkcs11_provider_finalize(p);
 138                 pkcs11_provider_unref(p);
 139         }
 140 }
 141
 142 /* lookup provider by name */
 143 static struct pkcs11_provider *
 144 pkcs11_provider_lookup(char *provider_id)
 145 {
 146         struct pkcs11_provider *p;
 147
 148         TAILQ_FOREACH(p, &pkcs11_providers, next) {
 149                 debug("check %p %s", p, p->name);
 150                 if (!strcmp(provider_id, p->name))
 151                         return (p);
 152         }
 153         return (NULL);
 154 }
 155
 156 /* unregister provider by name */
 157 int
 158 pkcs11_del_provider(char *provider_id)
 159 {
 160         struct pkcs11_provider *p;
 161
 162         if ((p = pkcs11_provider_lookup(provider_id)) != NULL) {
 163                 TAILQ_REMOVE(&pkcs11_providers, p, next);
 164                 pkcs11_provider_finalize(p);
 165                 pkcs11_provider_unref(p);
 166                 return (0);
 167         }
 168         return (-1);
 169 }
 170
 171 /* openssl callback for freeing an RSA key */
 172 static int
 173 pkcs11_rsa_finish(RSA *rsa)
 174 {
 175         struct pkcs11_key       *k11;
 176         int rv = -1;
 177
 178         if ((k11 = RSA_get_app_data(rsa)) != NULL) {
 179                 if (k11->orig_finish)
 180                         rv = k11->orig_finish(rsa);
 181                 if (k11->provider)
 182                         pkcs11_provider_unref(k11->provider);
 183                 if (k11->keyid)
 184                         xfree(k11->keyid);
 185                 xfree(k11);
 186         }
 187         return (rv);
 188 }
 189
 190 /* openssl callback doing the actual signing operation */
 191 static int
 192 pkcs11_rsa_private_encrypt(int flen, const u_char *from, u_char *to, RSA *rsa,
 193     int padding)
 194 {
 195         struct pkcs11_key       *k11;
 196         struct pkcs11_slotinfo  *si;
 197         CK_FUNCTION_LIST        *f;
 198         CK_OBJECT_HANDLE        obj;
 199         CK_ULONG                tlen = 0, nfound = 0;
 200         CK_RV                   rv;
 201         CK_OBJECT_CLASS         private_key_class = CKO_PRIVATE_KEY;
 202         CK_BBOOL                true_val = CK_TRUE;
 203         CK_MECHANISM            mech = {
 204                 CKM_RSA_PKCS, NULL_PTR, 0
 205         };
 206         CK_ATTRIBUTE            key_filter[] = {
 207                 {CKA_CLASS, NULL, sizeof(private_key_class) },
 208                 {CKA_ID, NULL, 0},
 209                 {CKA_SIGN, NULL, sizeof(true_val) }
 210         };
 211         char                    *pin, prompt[1024];
 212         int                     rval = -1;
 213
 214         /* some compilers complain about non-constant initializer so we
 215            use NULL in CK_ATTRIBUTE above and set the values here */
 216         key_filter[0].pValue = &private_key_class;
 217         key_filter[2].pValue = &true_val;
 218
 219         if ((k11 = RSA_get_app_data(rsa)) == NULL) {
 220                 error("RSA_get_app_data failed for rsa %p", rsa);
 221                 return (-1);
 222         }
 223         if (!k11->provider || !k11->provider->valid) {
 224                 error("no pkcs11 (valid) provider for rsa %p", rsa);
 225                 return (-1);
 226         }
 227         f = k11->provider->function_list;
 228         si = &k11->provider->slotinfo[k11->slotidx];
 229         if ((si->token.flags & CKF_LOGIN_REQUIRED) && !si->logged_in) {
 230                 if (!pkcs11_interactive) {
 231                         error("need pin");
 232                         return (-1);
 233                 }
 234                 snprintf(prompt, sizeof(prompt), "Enter PIN for '%s': ",
 235                     si->token.label);
 236                 pin = read_passphrase(prompt, RP_ALLOW_EOF);
 237                 if (pin == NULL)
 238                         return (-1);    /* bail out */
 239                 if ((rv = f->C_Login(si->session, CKU_USER, pin, strlen(pin)))
 240                     != CKR_OK) {
 241                         xfree(pin);
 242                         error("C_Login failed: %lu", rv);
 243                         return (-1);
 244                 }
 245                 xfree(pin);
 246                 si->logged_in = 1;
 247         }
 248         key_filter[1].pValue = k11->keyid;
 249         key_filter[1].ulValueLen = k11->keyid_len;
 250         if ((rv = f->C_FindObjectsInit(si->session, key_filter, 3)) != CKR_OK) {
 251                 error("C_FindObjectsInit failed: %lu", rv);
 252                 return (-1);
 253         }
 254         if ((rv = f->C_FindObjects(si->session, &obj, 1, &nfound)) != CKR_OK ||
 255             nfound != 1) {
 256                 error("C_FindObjects failed (%lu nfound): %lu", nfound, rv);
 257         } else if ((rv = f->C_SignInit(si->session, &mech, obj)) != CKR_OK) {
 258                 error("C_SignInit failed: %lu", rv);
 259         } else {
 260                 /* XXX handle CKR_BUFFER_TOO_SMALL */
 261                 tlen = RSA_size(rsa);
 262                 rv = f->C_Sign(si->session, (CK_BYTE *)from, flen, to, &tlen);
 263                 if (rv == CKR_OK)
 264                         rval = tlen;
 265                 else
 266                         error("C_Sign failed: %lu", rv);
 267         }
 268         if ((rv = f->C_FindObjectsFinal(si->session)) != CKR_OK)
 269                 error("C_FindObjectsFinal failed: %lu", rv);
 270         return (rval);
 271 }
 272
 273 static int
 274 pkcs11_rsa_private_decrypt(int flen, const u_char *from, u_char *to, RSA *rsa,
 275     int padding)
 276 {
 277         return (-1);
 278 }
 279
 280 /* redirect private key operations for rsa key to pkcs11 token */
 281 static int
 282 pkcs11_rsa_wrap(struct pkcs11_provider *provider, CK_ULONG slotidx,
 283     CK_ATTRIBUTE *keyid_attrib, RSA *rsa)
 284 {
 285         struct pkcs11_key       *k11;
 286         const RSA_METHOD        *def = RSA_get_default_method();
 287
 288         k11 = xcalloc(1, sizeof(*k11));
 289         k11->provider = provider;
 290         provider->refcount++;   /* provider referenced by RSA key */
 291         k11->slotidx = slotidx;
 292         /* identify key object on smartcard */
 293         k11->keyid_len = keyid_attrib->ulValueLen;
 294         k11->keyid = xmalloc(k11->keyid_len);
 295         memcpy(k11->keyid, keyid_attrib->pValue, k11->keyid_len);
 296         k11->orig_finish = def->finish;
 297         memcpy(&k11->rsa_method, def, sizeof(k11->rsa_method));
 298         k11->rsa_method.name = "pkcs11";
 299         k11->rsa_method.rsa_priv_enc = pkcs11_rsa_private_encrypt;
 300         k11->rsa_method.rsa_priv_dec = pkcs11_rsa_private_decrypt;
 301         k11->rsa_method.finish = pkcs11_rsa_finish;
 302         RSA_set_method(rsa, &k11->rsa_method);
 303         RSA_set_app_data(rsa, k11);
 304         return (0);
 305 }
 306
 307 /* remove trailing spaces */
 308 static void
 309 rmspace(char *buf, size_t len)
 310 {
 311         size_t i;
 312
 313         if (!len)
 314                 return;
 315         for (i = len - 1;  i > 0; i--)
 316                 if (i == len - 1 || buf[i] == ' ')
 317                         buf[i] = '\0';
 318                 else
 319                         break;
 320 }
 321
 322 /*
 323  * open a pkcs11 session and login if required.
 324  * if pin == NULL we delay login until key use
 325  */
 326 static int
 327 pkcs11_open_session(struct pkcs11_provider *p, CK_ULONG slotidx, char *pin)
 328 {
 329         CK_RV                   rv;
 330         CK_FUNCTION_LIST        *f;
 331         CK_SESSION_HANDLE       session;
 332         int                     login_required;
 333
 334         f = p->function_list;
 335         login_required = p->slotinfo[slotidx].token.flags & CKF_LOGIN_REQUIRED;
 336         if (pin && login_required && !strlen(pin)) {
 337                 error("pin required");
 338                 return (-1);
 339         }
 340         if ((rv = f->C_OpenSession(p->slotlist[slotidx], CKF_RW_SESSION|
 341             CKF_SERIAL_SESSION, NULL, NULL, &session))
 342             != CKR_OK) {
 343                 error("C_OpenSession failed: %lu", rv);
 344                 return (-1);
 345         }
 346         if (login_required && pin) {
 347                 if ((rv = f->C_Login(session, CKU_USER, pin, strlen(pin)))
 348                     != CKR_OK) {
 349                         error("C_Login failed: %lu", rv);
 350                         if ((rv = f->C_CloseSession(session)) != CKR_OK)
 351                                 error("C_CloseSession failed: %lu", rv);
 352                         return (-1);
 353                 }
 354                 p->slotinfo[slotidx].logged_in = 1;
 355         }
 356         p->slotinfo[slotidx].session = session;
 357         return (0);
 358 }
 359
 360 /*
 361  * lookup public keys for token in slot identified by slotidx,
 362  * add 'wrapped' public keys to the 'keysp' array and increment nkeys.
 363  * keysp points to an (possibly empty) array with *nkeys keys.
 364  */
 365 static int
 366 pkcs11_fetch_keys(struct pkcs11_provider *p, CK_ULONG slotidx, Key ***keysp,
 367     int *nkeys)
 368 {
 369         Key                     *key;
 370         RSA                     *rsa;
 371         int                     i;
 372         CK_RV                   rv;
 373         CK_OBJECT_HANDLE        obj;
 374         CK_ULONG                nfound;
 375         CK_SESSION_HANDLE       session;
 376         CK_FUNCTION_LIST        *f;
 377         CK_OBJECT_CLASS         pubkey_class = CKO_PUBLIC_KEY;
 378         CK_ATTRIBUTE            pubkey_filter[] = {
 379                 { CKA_CLASS, NULL, sizeof(pubkey_class) }
 380         };
 381         CK_ATTRIBUTE            attribs[] = {
 382                 { CKA_ID, NULL, 0 },
 383                 { CKA_MODULUS, NULL, 0 },
 384                 { CKA_PUBLIC_EXPONENT, NULL, 0 }
 385         };
 386
 387         /* some compilers complain about non-constant initializer so we
 388            use NULL in CK_ATTRIBUTE above and set the value here */
 389         pubkey_filter[0].pValue = &pubkey_class;
 390
 391         f = p->function_list;
 392         session = p->slotinfo[slotidx].session;
 393         /* setup a filter the looks for public keys */
 394         if ((rv = f->C_FindObjectsInit(session, pubkey_filter, 1)) != CKR_OK) {
 395                 error("C_FindObjectsInit failed: %lu", rv);
 396                 return (-1);
 397         }
 398         while (1) {
 399                 /* XXX 3 attributes in attribs[] */
 400                 for (i = 0; i < 3; i++) {
 401                         attribs[i].pValue = NULL;
 402                         attribs[i].ulValueLen = 0;
 403                 }
 404                 if ((rv = f->C_FindObjects(session, &obj, 1, &nfound)) != CKR_OK
 405                     || nfound == 0)
 406                         break;
 407                 /* found a key, so figure out size of the attributes */
 408                 if ((rv = f->C_GetAttributeValue(session, obj, attribs, 3))
 409                     != CKR_OK) {
 410                         error("C_GetAttributeValue failed: %lu", rv);
 411                         continue;
 412                 }
 413                 /* allocate buffers for attributes, XXX check ulValueLen? */
 414                 for (i = 0; i < 3; i++)
 415                         attribs[i].pValue = xmalloc(attribs[i].ulValueLen);
 416                 /* retrieve ID, modulus and public exponent of RSA key */
 417                 if ((rv = f->C_GetAttributeValue(session, obj, attribs, 3))
 418                     != CKR_OK) {
 419                         error("C_GetAttributeValue failed: %lu", rv);
 420                 } else if ((rsa = RSA_new()) == NULL) {
 421                         error("RSA_new failed");
 422                 } else {
 423                         rsa->n = BN_bin2bn(attribs[1].pValue,
 424                             attribs[1].ulValueLen, NULL);
 425                         rsa->e = BN_bin2bn(attribs[2].pValue,
 426                             attribs[2].ulValueLen, NULL);
 427                         if (rsa->n && rsa->e &&
 428                             pkcs11_rsa_wrap(p, slotidx, &attribs[0], rsa) == 0) {
 429                                 key = key_new(KEY_UNSPEC);
 430                                 key->rsa = rsa;
 431                                 key->type = KEY_RSA;
 432                                 key->flags |= KEY_FLAG_EXT;
 433                                 /* expand key array and add key */
 434                                 *keysp = xrealloc(*keysp, *nkeys + 1,
 435                                     sizeof(Key *));
 436                                 (*keysp)[*nkeys] = key;
 437                                 *nkeys = *nkeys + 1;
 438                                 debug("have %d keys", *nkeys);
 439                         } else {
 440                                 RSA_free(rsa);
 441                         }
 442                 }
 443                 for (i = 0; i < 3; i++)
 444                         xfree(attribs[i].pValue);
 445         }
 446         if ((rv = f->C_FindObjectsFinal(session)) != CKR_OK)
 447                 error("C_FindObjectsFinal failed: %lu", rv);
 448         return (0);
 449 }
 450
 451 /* register a new provider, fails if provider already exists */
 452 int
 453 pkcs11_add_provider(char *provider_id, char *pin, Key ***keyp)
 454 {
 455         int nkeys, need_finalize = 0;
 456         struct pkcs11_provider *p = NULL;
 457         void *handle = NULL;
 458         CK_RV (*getfunctionlist)(CK_FUNCTION_LIST **);
 459         CK_RV rv;
 460         CK_FUNCTION_LIST *f = NULL;
 461         CK_TOKEN_INFO *token;
 462         CK_ULONG i;
 463
 464         *keyp = NULL;
 465         if (pkcs11_provider_lookup(provider_id) != NULL) {
 466                 error("provider already registered: %s", provider_id);
 467                 goto fail;
 468         }
 469         /* open shared pkcs11-libarary */
 470         if ((handle = dlopen(provider_id, RTLD_NOW)) == NULL) {
 471                 error("dlopen %s failed: %s", provider_id, dlerror());
 472                 goto fail;
 473         }
 474         if ((getfunctionlist = dlsym(handle, "C_GetFunctionList")) == NULL) {
 475                 error("dlsym(C_GetFunctionList) failed: %s", dlerror());
 476                 goto fail;
 477         }
 478         p = xcalloc(1, sizeof(*p));
 479         p->name = xstrdup(provider_id);
 480         p->handle = handle;
 481         /* setup the pkcs11 callbacks */
 482         if ((rv = (*getfunctionlist)(&f)) != CKR_OK) {
 483                 error("C_GetFunctionList failed: %lu", rv);
 484                 goto fail;
 485         }
 486         p->function_list = f;
 487         if ((rv = f->C_Initialize(NULL)) != CKR_OK) {
 488                 error("C_Initialize failed: %lu", rv);
 489                 goto fail;
 490         }
 491         need_finalize = 1;
 492         if ((rv = f->C_GetInfo(&p->info)) != CKR_OK) {
 493                 error("C_GetInfo failed: %lu", rv);
 494                 goto fail;
 495         }
 496         rmspace(p->info.manufacturerID, sizeof(p->info.manufacturerID));
 497         rmspace(p->info.libraryDescription, sizeof(p->info.libraryDescription));
 498         debug("manufacturerID <%s> cryptokiVersion %d.%d"
 499             " libraryDescription <%s> libraryVersion %d.%d",
 500             p->info.manufacturerID,
 501             p->info.cryptokiVersion.major,
 502             p->info.cryptokiVersion.minor,
 503             p->info.libraryDescription,
 504             p->info.libraryVersion.major,
 505             p->info.libraryVersion.minor);
 506         if ((rv = f->C_GetSlotList(CK_TRUE, NULL, &p->nslots)) != CKR_OK) {
 507                 error("C_GetSlotList failed: %lu", rv);
 508                 goto fail;
 509         }
 510         if (p->nslots == 0) {
 511                 error("no slots");
 512                 goto fail;
 513         }
 514         p->slotlist = xcalloc(p->nslots, sizeof(CK_SLOT_ID));
 515         if ((rv = f->C_GetSlotList(CK_TRUE, p->slotlist, &p->nslots))
 516             != CKR_OK) {
 517                 error("C_GetSlotList failed: %lu", rv);
 518                 goto fail;
 519         }
 520         p->slotinfo = xcalloc(p->nslots, sizeof(struct pkcs11_slotinfo));
 521         p->valid = 1;
 522         nkeys = 0;
 523         for (i = 0; i < p->nslots; i++) {
 524                 token = &p->slotinfo[i].token;
 525                 if ((rv = f->C_GetTokenInfo(p->slotlist[i], token))
 526                     != CKR_OK) {
 527                         error("C_GetTokenInfo failed: %lu", rv);
 528                         continue;
 529                 }
 530                 rmspace(token->label, sizeof(token->label));
 531                 rmspace(token->manufacturerID, sizeof(token->manufacturerID));
 532                 rmspace(token->model, sizeof(token->model));
 533                 rmspace(token->serialNumber, sizeof(token->serialNumber));
 534                 debug("label <%s> manufacturerID <%s> model <%s> serial <%s>"
 535                     " flags 0x%lx",
 536                     token->label, token->manufacturerID, token->model,
 537                     token->serialNumber, token->flags);
 538                 /* open session, login with pin and retrieve public keys */
 539                 if (pkcs11_open_session(p, i, pin) == 0)
 540                         pkcs11_fetch_keys(p, i, keyp, &nkeys);
 541         }
 542         if (nkeys > 0) {
 543                 TAILQ_INSERT_TAIL(&pkcs11_providers, p, next);
 544                 p->refcount++;  /* add to provider list */
 545                 return (nkeys);
 546         }
 547         error("no keys");
 548         /* don't add the provider, since it does not have any keys */
 549 fail:
 550         if (need_finalize && (rv = f->C_Finalize(NULL)) != CKR_OK)
 551                 error("C_Finalize failed: %lu", rv);
 552         if (p) {
 553                 if (p->slotlist)
 554                         xfree(p->slotlist);
 555                 if (p->slotinfo)
 556                         xfree(p->slotinfo);
 557                 xfree(p);
 558         }
 559         if (handle)
 560                 dlclose(handle);
 561         return (-1);
 562 }
 563
 564 #endif /* ENABLE_PKCS11 */