contrib/pam_modules/pam_passwdqc/pam_passwdqc.c

   1 /*
   2  * Copyright (c) 2000-2002 by Solar Designer. See LICENSE.
   3  */
   4
   5 #define _XOPEN_SOURCE 500
   6 #define _XOPEN_SOURCE_EXTENDED
   7 #define _XOPEN_VERSION 500
   8 #include <stdio.h>
   9 #include <stdlib.h>
  10 #include <stdarg.h>
  11 #include <string.h>
  12 #include <limits.h>
  13 #include <unistd.h>
  14 #include <pwd.h>
  15 #ifdef HAVE_SHADOW
  16 #include <shadow.h>
  17 #endif
  18
  19 #define PAM_SM_PASSWORD
  20 #ifndef LINUX_PAM
  21 #include <security/pam_appl.h>
  22 #endif
  23 #include <security/pam_modules.h>
  24
  25 #include "pam_macros.h"
  26
  27 #if !defined(PAM_EXTERN) && !defined(PAM_STATIC)
  28 #define PAM_EXTERN                      extern
  29 #endif
  30
  31 #if !defined(PAM_AUTHTOK_RECOVERY_ERR) && defined(PAM_AUTHTOK_RECOVER_ERR)
  32 #define PAM_AUTHTOK_RECOVERY_ERR        PAM_AUTHTOK_RECOVER_ERR
  33 #endif
  34
  35 #if defined(__sun__) && !defined(LINUX_PAM) && !defined(_OPENPAM)
  36 /* Sun's PAM doesn't use const here */
  37 #define lo_const
  38 #else
  39 #define lo_const                        const
  40 #endif
  41 typedef lo_const void *pam_item_t;
  42
  43 #include "passwdqc.h"
  44
  45 #define F_ENFORCE_MASK                  0x00000003
  46 #define F_ENFORCE_USERS                 0x00000001
  47 #define F_ENFORCE_ROOT                  0x00000002
  48 #define F_ENFORCE_EVERYONE              F_ENFORCE_MASK
  49 #define F_NON_UNIX                      0x00000004
  50 #define F_ASK_OLDAUTHTOK_MASK           0x00000030
  51 #define F_ASK_OLDAUTHTOK_PRELIM         0x00000010
  52 #define F_ASK_OLDAUTHTOK_UPDATE         0x00000020
  53 #define F_CHECK_OLDAUTHTOK              0x00000040
  54 #define F_USE_FIRST_PASS                0x00000100
  55 #define F_USE_AUTHTOK                   0x00000200
  56
  57 typedef struct {
  58         passwdqc_params_t qc;
  59         int flags;
  60         int retry;
  61 } params_t;
  62
  63 static params_t defaults = {
  64         {
  65                 {INT_MAX, 24, 12, 8, 7},        /* min */
  66                 40,                             /* max */
  67                 3,                              /* passphrase_words */
  68                 4,                              /* match_length */
  69                 1,                              /* similar_deny */
  70                 42                              /* random_bits */
  71         },
  72         F_ENFORCE_EVERYONE,                     /* flags */
  73         3                                       /* retry */
  74 };
  75
  76 #define PROMPT_OLDPASS \
  77         "Enter current password: "
  78 #define PROMPT_NEWPASS1 \
  79         "Enter new password: "
  80 #define PROMPT_NEWPASS2 \
  81         "Re-type new password: "
  82
  83 #define MESSAGE_MISCONFIGURED \
  84         "System configuration error.  Please contact your administrator."
  85 #define MESSAGE_INVALID_OPTION \
  86         "pam_passwdqc: Invalid option: \"%s\"."
  87 #define MESSAGE_INTRO_PASSWORD \
  88         "\nYou can now choose the new password.\n"
  89 #define MESSAGE_INTRO_BOTH \
  90         "\nYou can now choose the new password or passphrase.\n"
  91 #define MESSAGE_EXPLAIN_PASSWORD_1 \
  92         "A valid password should be a mix of upper and lower case letters,\n" \
  93         "digits and other characters.  You can use a%s %d character long\n" \
  94         "password with characters from at least 3 of these 4 classes.\n" \
  95         "Characters that form a common pattern are discarded by the check.\n"
  96 #define MESSAGE_EXPLAIN_PASSWORD_2 \
  97         "A valid password should be a mix of upper and lower case letters,\n" \
  98         "digits and other characters.  You can use a%s %d character long\n" \
  99         "password with characters from at least 3 of these 4 classes, or\n" \
 100         "a%s %d character long password containing characters from all the\n" \
 101         "classes.  Characters that form a common pattern are discarded by\n" \
 102         "the check.\n"
 103 #define MESSAGE_EXPLAIN_PASSPHRASE \
 104         "A passphrase should be of at least %d words, %d to %d characters\n" \
 105         "long and contain enough different characters.\n"
 106 #define MESSAGE_RANDOM \
 107         "Alternatively, if noone else can see your terminal now, you can\n" \
 108         "pick this as your password: \"%s\".\n"
 109 #define MESSAGE_RANDOMONLY \
 110         "This system is configured to permit randomly generated passwords\n" \
 111         "only.  If noone else can see your terminal now, you can pick this\n" \
 112         "as your password: \"%s\".  Otherwise, come back later.\n"
 113 #define MESSAGE_RANDOMFAILED \
 114         "This system is configured to use randomly generated passwords\n" \
 115         "only, but the attempt to generate a password has failed.  This\n" \
 116         "could happen for a number of reasons: you could have requested\n" \
 117         "an impossible password length, or the access to kernel random\n" \
 118         "number pool could have failed."
 119 #define MESSAGE_TOOLONG \
 120         "This password may be too long for some services.  Choose another."
 121 #define MESSAGE_TRUNCATED \
 122         "Warning: your longer password will be truncated to 8 characters."
 123 #define MESSAGE_WEAKPASS \
 124         "Weak password: %s."
 125 #define MESSAGE_NOTRANDOM \
 126         "Sorry, you've mistyped the password that was generated for you."
 127 #define MESSAGE_MISTYPED \
 128         "Sorry, passwords do not match."
 129 #define MESSAGE_RETRY \
 130         "Try again."
 131
 132 static int converse(pam_handle_t *pamh, int style, lo_const char *text,
 133     struct pam_response **resp)
 134 {
 135         struct pam_conv *conv;
 136         struct pam_message msg, *pmsg;
 137         int status;
 138
 139         status = pam_get_item(pamh, PAM_CONV, (pam_item_t *)&conv);
 140         if (status != PAM_SUCCESS)
 141                 return status;
 142
 143         pmsg = &msg;
 144         msg.msg_style = style;
 145         msg.msg = text;
 146
 147         *resp = NULL;
 148         return conv->conv(1, (lo_const struct pam_message **)&pmsg, resp,
 149             conv->appdata_ptr);
 150 }
 151
 152 #ifdef __GNUC__
 153 __attribute__ ((format (printf, 3, 4)))
 154 #endif
 155 static int say(pam_handle_t *pamh, int style, const char *format, ...)
 156 {
 157         va_list args;
 158         char buffer[0x800];
 159         int needed;
 160         struct pam_response *resp;
 161         int status;
 162
 163         va_start(args, format);
 164         needed = vsnprintf(buffer, sizeof(buffer), format, args);
 165         va_end(args);
 166
 167         if ((unsigned int)needed < sizeof(buffer)) {
 168                 status = converse(pamh, style, buffer, &resp);
 169                 _pam_overwrite(buffer);
 170         } else {
 171                 status = PAM_ABORT;
 172                 memset(buffer, 0, sizeof(buffer));
 173         }
 174
 175         return status;
 176 }
 177
 178 static int check_max(params_t *params, pam_handle_t *pamh, const char *newpass)
 179 {
 180         if ((int)strlen(newpass) > params->qc.max) {
 181                 if (params->qc.max != 8) {
 182                         say(pamh, PAM_ERROR_MSG, MESSAGE_TOOLONG);
 183                         return -1;
 184                 }
 185                 say(pamh, PAM_TEXT_INFO, MESSAGE_TRUNCATED);
 186         }
 187
 188         return 0;
 189 }
 190
 191 static int parse(params_t *params, pam_handle_t *pamh,
 192     int argc, const char **argv)
 193 {
 194         const char *p;
 195         char *e;
 196         int i;
 197         unsigned long v;
 198
 199         while (argc) {
 200                 if (!strncmp(*argv, "min=", 4)) {
 201                         p = *argv + 4;
 202                         for (i = 0; i < 5; i++) {
 203                                 if (!strncmp(p, "disabled", 8)) {
 204                                         v = INT_MAX;
 205                                         p += 8;
 206                                 } else {
 207                                         v = strtoul(p, &e, 10);
 208                                         p = e;
 209                                 }
 210                                 if (i < 4 && *p++ != ',') break;
 211                                 if (v > INT_MAX) break;
 212                                 if (i && (int)v > params->qc.min[i - 1]) break;
 213                                 params->qc.min[i] = v;
 214                         }
 215                         if (*p) break;
 216                 } else
 217                 if (!strncmp(*argv, "max=", 4)) {
 218                         v = strtoul(*argv + 4, &e, 10);
 219                         if (*e || v < 8 || v > INT_MAX) break;
 220                         params->qc.max = v;
 221                 } else
 222                 if (!strncmp(*argv, "passphrase=", 11)) {
 223                         v = strtoul(*argv + 11, &e, 10);
 224                         if (*e || v > INT_MAX) break;
 225                         params->qc.passphrase_words = v;
 226                 } else
 227                 if (!strncmp(*argv, "match=", 6)) {
 228                         v = strtoul(*argv + 6, &e, 10);
 229                         if (*e || v > INT_MAX) break;
 230                         params->qc.match_length = v;
 231                 } else
 232                 if (!strncmp(*argv, "similar=", 8)) {
 233                         if (!strcmp(*argv + 8, "permit"))
 234                                 params->qc.similar_deny = 0;
 235                         else
 236                         if (!strcmp(*argv + 8, "deny"))
 237                                 params->qc.similar_deny = 1;
 238                         else
 239                                 break;
 240                 } else
 241                 if (!strncmp(*argv, "random=", 7)) {
 242                         v = strtoul(*argv + 7, &e, 10);
 243                         if (!strcmp(e, ",only")) {
 244                                 e += 5;
 245                                 params->qc.min[4] = INT_MAX;
 246                         }
 247                         if (*e || v > INT_MAX) break;
 248                         params->qc.random_bits = v;
 249                 } else
 250                 if (!strncmp(*argv, "enforce=", 8)) {
 251                         params->flags &= ~F_ENFORCE_MASK;
 252                         if (!strcmp(*argv + 8, "users"))
 253                                 params->flags |= F_ENFORCE_USERS;
 254                         else
 255                         if (!strcmp(*argv + 8, "everyone"))
 256                                 params->flags |= F_ENFORCE_EVERYONE;
 257                         else
 258                         if (strcmp(*argv + 8, "none"))
 259                                 break;
 260                 } else
 261                 if (!strcmp(*argv, "non-unix")) {
 262                         if (params->flags & F_CHECK_OLDAUTHTOK) break;
 263                         params->flags |= F_NON_UNIX;
 264                 } else
 265                 if (!strncmp(*argv, "retry=", 6)) {
 266                         v = strtoul(*argv + 6, &e, 10);
 267                         if (*e || v > INT_MAX) break;
 268                         params->retry = v;
 269                 } else
 270                 if (!strncmp(*argv, "ask_oldauthtok", 14)) {
 271                         params->flags &= ~F_ASK_OLDAUTHTOK_MASK;
 272                         if (params->flags & F_USE_FIRST_PASS) break;
 273                         if (!strcmp(*argv + 14, "=update"))
 274                                 params->flags |= F_ASK_OLDAUTHTOK_UPDATE;
 275                         else
 276                         if (!(*argv)[14])
 277                                 params->flags |= F_ASK_OLDAUTHTOK_PRELIM;
 278                         else
 279                                 break;
 280                 } else
 281                 if (!strcmp(*argv, "check_oldauthtok")) {
 282                         if (params->flags & F_NON_UNIX) break;
 283                         params->flags |= F_CHECK_OLDAUTHTOK;
 284                 } else
 285                 if (!strcmp(*argv, "use_first_pass")) {
 286                         if (params->flags & F_ASK_OLDAUTHTOK_MASK) break;
 287                         params->flags |= F_USE_FIRST_PASS | F_USE_AUTHTOK;
 288                 } else
 289                 if (!strcmp(*argv, "use_authtok")) {
 290                         params->flags |= F_USE_AUTHTOK;
 291                 } else
 292                         break;
 293                 argc--; argv++;
 294         }
 295
 296         if (argc) {
 297                 say(pamh, PAM_ERROR_MSG, getuid() != 0 ?
 298                     MESSAGE_MISCONFIGURED : MESSAGE_INVALID_OPTION, *argv);
 299                 return PAM_ABORT;
 300         }
 301
 302         return PAM_SUCCESS;
 303 }
 304
 305 PAM_EXTERN int pam_sm_chauthtok(pam_handle_t *pamh, int flags,
 306     int argc, const char **argv)
 307 {
 308         params_t params;
 309         struct pam_response *resp;
 310         struct passwd *pw, fake_pw;
 311 #ifdef HAVE_SHADOW
 312         struct spwd *spw;
 313 #endif
 314         char *user, *oldpass, *newpass, *randompass;
 315         const char *reason;
 316         int ask_oldauthtok;
 317         int randomonly, enforce, retries_left, retry_wanted;
 318         int status;
 319
 320         params = defaults;
 321         status = parse(&params, pamh, argc, argv);
 322         if (status != PAM_SUCCESS)
 323                 return status;
 324
 325         ask_oldauthtok = 0;
 326         if (flags & PAM_PRELIM_CHECK) {
 327                 if (params.flags & F_ASK_OLDAUTHTOK_PRELIM)
 328                         ask_oldauthtok = 1;
 329         } else
 330         if (flags & PAM_UPDATE_AUTHTOK) {
 331                 if (params.flags & F_ASK_OLDAUTHTOK_UPDATE)
 332                         ask_oldauthtok = 1;
 333         } else
 334                 return PAM_SERVICE_ERR;
 335
 336         if (ask_oldauthtok && getuid() != 0) {
 337                 status = converse(pamh, PAM_PROMPT_ECHO_OFF,
 338                     PROMPT_OLDPASS, &resp);
 339
 340                 if (status == PAM_SUCCESS) {
 341                         if (resp && resp->resp) {
 342                                 status = pam_set_item(pamh,
 343                                     PAM_OLDAUTHTOK, resp->resp);
 344                                 _pam_drop_reply(resp, 1);
 345                         } else
 346                                 status = PAM_AUTHTOK_RECOVERY_ERR;
 347                 }
 348
 349                 if (status != PAM_SUCCESS)
 350                         return status;
 351         }
 352
 353         if (flags & PAM_PRELIM_CHECK)
 354                 return status;
 355
 356         status = pam_get_item(pamh, PAM_USER, (pam_item_t *)&user);
 357         if (status != PAM_SUCCESS)
 358                 return status;
 359
 360         status = pam_get_item(pamh, PAM_OLDAUTHTOK, (pam_item_t *)&oldpass);
 361         if (status != PAM_SUCCESS)
 362                 return status;
 363
 364         if (params.flags & F_NON_UNIX) {
 365                 pw = &fake_pw;
 366                 pw->pw_name = user;
 367                 pw->pw_gecos = "";
 368         } else {
 369                 pw = getpwnam(user);
 370                 endpwent();
 371                 if (!pw)
 372                         return PAM_USER_UNKNOWN;
 373                 if ((params.flags & F_CHECK_OLDAUTHTOK) && getuid() != 0) {
 374                         if (!oldpass)
 375                                 status = PAM_AUTH_ERR;
 376                         else
 377 #ifdef HAVE_SHADOW
 378                         if (!strcmp(pw->pw_passwd, "x")) {
 379                                 spw = getspnam(user);
 380                                 endspent();
 381                                 if (spw) {
 382                                         if (strcmp(crypt(oldpass, spw->sp_pwdp),
 383                                             spw->sp_pwdp))
 384                                                 status = PAM_AUTH_ERR;
 385                                         memset(spw->sp_pwdp, 0,
 386                                             strlen(spw->sp_pwdp));
 387                                 } else
 388                                         status = PAM_AUTH_ERR;
 389                         } else
 390 #endif
 391                         if (strcmp(crypt(oldpass, pw->pw_passwd),
 392                             pw->pw_passwd))
 393                                 status = PAM_AUTH_ERR;
 394                 }
 395                 memset(pw->pw_passwd, 0, strlen(pw->pw_passwd));
 396                 if (status != PAM_SUCCESS)
 397                         return status;
 398         }
 399
 400         randomonly = params.qc.min[4] > params.qc.max;
 401
 402         if (getuid() != 0)
 403                 enforce = params.flags & F_ENFORCE_USERS;
 404         else
 405                 enforce = params.flags & F_ENFORCE_ROOT;
 406
 407         if (params.flags & F_USE_AUTHTOK) {
 408                 status = pam_get_item(pamh, PAM_AUTHTOK,
 409                     (pam_item_t *)&newpass);
 410                 if (status != PAM_SUCCESS)
 411                         return status;
 412                 if (!newpass || (check_max(&params, pamh, newpass) && enforce))
 413                         return PAM_AUTHTOK_ERR;
 414                 reason = _passwdqc_check(&params.qc, newpass, oldpass, pw);
 415                 if (reason) {
 416                         say(pamh, PAM_ERROR_MSG, MESSAGE_WEAKPASS, reason);
 417                         if (enforce)
 418                                 status = PAM_AUTHTOK_ERR;
 419                 }
 420                 return status;
 421         }
 422
 423         retries_left = params.retry;
 424
 425 retry:
 426         retry_wanted = 0;
 427
 428         if (!randomonly &&
 429             params.qc.passphrase_words && params.qc.min[2] <= params.qc.max)
 430                 status = say(pamh, PAM_TEXT_INFO, MESSAGE_INTRO_BOTH);
 431         else
 432                 status = say(pamh, PAM_TEXT_INFO, MESSAGE_INTRO_PASSWORD);
 433         if (status != PAM_SUCCESS)
 434                 return status;
 435
 436         if (!randomonly && params.qc.min[3] <= params.qc.min[4])
 437                 status = say(pamh, PAM_TEXT_INFO, MESSAGE_EXPLAIN_PASSWORD_1,
 438                     params.qc.min[3] == 8 || params.qc.min[3] == 11 ? "n" : "",
 439                     params.qc.min[3]);
 440         else
 441         if (!randomonly)
 442                 status = say(pamh, PAM_TEXT_INFO, MESSAGE_EXPLAIN_PASSWORD_2,
 443                     params.qc.min[3] == 8 || params.qc.min[3] == 11 ? "n" : "",
 444                     params.qc.min[3],
 445                     params.qc.min[4] == 8 || params.qc.min[4] == 11 ? "n" : "",
 446                     params.qc.min[4]);
 447         if (status != PAM_SUCCESS)
 448                 return status;
 449
 450         if (!randomonly &&
 451             params.qc.passphrase_words &&
 452             params.qc.min[2] <= params.qc.max) {
 453                 status = say(pamh, PAM_TEXT_INFO, MESSAGE_EXPLAIN_PASSPHRASE,
 454                     params.qc.passphrase_words,
 455                     params.qc.min[2], params.qc.max);
 456                 if (status != PAM_SUCCESS)
 457                         return status;
 458         }
 459
 460         randompass = _passwdqc_random(&params.qc);
 461         if (randompass) {
 462                 status = say(pamh, PAM_TEXT_INFO, randomonly ?
 463                     MESSAGE_RANDOMONLY : MESSAGE_RANDOM, randompass);
 464                 if (status != PAM_SUCCESS) {
 465                         _pam_overwrite(randompass);
 466                         randompass = NULL;
 467                 }
 468         } else
 469         if (randomonly) {
 470                 say(pamh, PAM_ERROR_MSG, getuid() != 0 ?
 471                     MESSAGE_MISCONFIGURED : MESSAGE_RANDOMFAILED);
 472                 return PAM_AUTHTOK_ERR;
 473         }
 474
 475         status = converse(pamh, PAM_PROMPT_ECHO_OFF, PROMPT_NEWPASS1, &resp);
 476         if (status == PAM_SUCCESS && (!resp || !resp->resp))
 477                 status = PAM_AUTHTOK_ERR;
 478
 479         if (status != PAM_SUCCESS) {
 480                 if (randompass) _pam_overwrite(randompass);
 481                 return status;
 482         }
 483
 484         newpass = strdup(resp->resp);
 485
 486         _pam_drop_reply(resp, 1);
 487
 488         if (!newpass) {
 489                 if (randompass) _pam_overwrite(randompass);
 490                 return PAM_AUTHTOK_ERR;
 491         }
 492
 493         if (check_max(&params, pamh, newpass) && enforce) {
 494                 status = PAM_AUTHTOK_ERR;
 495                 retry_wanted = 1;
 496         }
 497
 498         reason = NULL;
 499         if (status == PAM_SUCCESS &&
 500             (!randompass || !strstr(newpass, randompass)) &&
 501             (randomonly ||
 502             (reason = _passwdqc_check(&params.qc, newpass, oldpass, pw)))) {
 503                 if (randomonly)
 504                         say(pamh, PAM_ERROR_MSG, MESSAGE_NOTRANDOM);
 505                 else
 506                         say(pamh, PAM_ERROR_MSG, MESSAGE_WEAKPASS, reason);
 507                 if (enforce) {
 508                         status = PAM_AUTHTOK_ERR;
 509                         retry_wanted = 1;
 510                 }
 511         }
 512
 513         if (status == PAM_SUCCESS)
 514                 status = converse(pamh, PAM_PROMPT_ECHO_OFF,
 515                     PROMPT_NEWPASS2, &resp);
 516         if (status == PAM_SUCCESS) {
 517                 if (resp && resp->resp) {
 518                         if (strcmp(newpass, resp->resp)) {
 519                                 status = say(pamh,
 520                                     PAM_ERROR_MSG, MESSAGE_MISTYPED);
 521                                 if (status == PAM_SUCCESS) {
 522                                         status = PAM_AUTHTOK_ERR;
 523                                         retry_wanted = 1;
 524                                 }
 525                         }
 526                         _pam_drop_reply(resp, 1);
 527                 } else
 528                         status = PAM_AUTHTOK_ERR;
 529         }
 530
 531         if (status == PAM_SUCCESS)
 532                 status = pam_set_item(pamh, PAM_AUTHTOK, newpass);
 533
 534         if (randompass) _pam_overwrite(randompass);
 535         _pam_overwrite(newpass);
 536         free(newpass);
 537
 538         if (retry_wanted && --retries_left > 0) {
 539                 status = say(pamh, PAM_TEXT_INFO, MESSAGE_RETRY);
 540                 if (status == PAM_SUCCESS)
 541                         goto retry;
 542         }
 543
 544         return status;
 545 }
 546
 547 #ifdef PAM_MODULE_ENTRY
 548 PAM_MODULE_ENTRY("pam_passwdqc");
 549 #elif defined(PAM_STATIC)
 550 struct pam_module _pam_passwdqc_modstruct = {
 551         "pam_passwdqc",
 552         NULL,
 553         NULL,
 554         NULL,
 555         NULL,
 556         NULL,
 557         pam_sm_chauthtok
 558 };
 559 #endif