lib/kadm5/password_quality.c

   1 /*
   2  * Copyright (c) 1997-2000, 2003-2005 Kungliga Tekniska Högskolan
   3  * (Royal Institute of Technology, Stockholm, Sweden).
   4  * All rights reserved.
   5  *
   6  * Redistribution and use in source and binary forms, with or without
   7  * modification, are permitted provided that the following conditions
   8  * are met:
   9  *
  10  * 1. Redistributions of source code must retain the above copyright
  11  *    notice, this list of conditions and the following disclaimer.
  12  *
  13  * 2. Redistributions in binary form must reproduce the above copyright
  14  *    notice, this list of conditions and the following disclaimer in the
  15  *    documentation and/or other materials provided with the distribution.
  16  *
  17  * 3. Neither the name of the Institute nor the names of its contributors
  18  *    may be used to endorse or promote products derived from this software
  19  *    without specific prior written permission.
  20  *
  21  * THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND
  22  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  23  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  24  * ARE DISCLAIMED.  IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE
  25  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  26  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  27  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  28  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  29  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  30  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  31  * SUCH DAMAGE.
  32  */
  33
  34 #include "kadm5_locl.h"
  35 #include "kadm5-pwcheck.h"
  36
  37 #ifdef HAVE_SYS_WAIT_H
  38 #include <sys/wait.h>
  39 #endif
  40 #ifdef HAVE_DLFCN_H
  41 #include <dlfcn.h>
  42 #endif
  43
  44 static int
  45 min_length_passwd_quality (krb5_context context,
  46                            krb5_principal principal,
  47                            krb5_data *pwd,
  48                            const char *opaque,
  49                            char *message,
  50                            size_t length)
  51 {
  52     uint32_t min_length = krb5_config_get_int_default(context, NULL, 6,
  53                                                       "password_quality",
  54                                                       "min_length",
  55                                                       NULL);
  56
  57     if (pwd->length < min_length) {
  58         strlcpy(message, "Password too short", length);
  59         return 1;
  60     } else
  61         return 0;
  62 }
  63
  64 static const char *
  65 min_length_passwd_quality_v0 (krb5_context context,
  66                               krb5_principal principal,
  67                               krb5_data *pwd)
  68 {
  69     static char message[1024];
  70     int ret;
  71
  72     message[0] = '\0';
  73
  74     ret = min_length_passwd_quality(context, principal, pwd, NULL,
  75                                     message, sizeof(message));
  76     if (ret)
  77         return message;
  78     return NULL;
  79 }
  80
  81
  82 static int
  83 char_class_passwd_quality (krb5_context context,
  84                            krb5_principal principal,
  85                            krb5_data *pwd,
  86                            const char *opaque,
  87                            char *message,
  88                            size_t length)
  89 {
  90     const char *classes[] = {
  91         "ABCDEFGHIJKLMNOPQRSTUVWXYZ",
  92         "abcdefghijklmnopqrstuvwxyz",
  93         "1234567890",
  94         "!@#$%^&*()/?<>,.{[]}\\|'~`\" "
  95     };
  96     int counter = 0, req_classes;
  97     size_t i, len;
  98     char *pw;
  99
 100     req_classes = krb5_config_get_int_default(context, NULL, 3,
 101                                               "password_quality",
 102                                               "min_classes",
 103                                               NULL);
 104
 105     len = pwd->length + 1;
 106     pw = malloc(len);
 107     if (pw == NULL) {
 108         strlcpy(message, "out of memory", length);
 109         return 1;
 110     }
 111     strlcpy(pw, pwd->data, len);
 112     len = strlen(pw);
 113
 114     for (i = 0; i < sizeof(classes)/sizeof(classes[0]); i++) {
 115         if (strcspn(pw, classes[i]) < len)
 116             counter++;
 117     }
 118     memset(pw, 0, pwd->length + 1);
 119     free(pw);
 120     if (counter < req_classes) {
 121         snprintf(message, length,
 122             "Password doesn't meet complexity requirement.\n"
 123             "Add more characters from the following classes:\n"
 124             "1. English uppercase characters (A through Z)\n"
 125             "2. English lowercase characters (a through z)\n"
 126             "3. Base 10 digits (0 through 9)\n"
 127             "4. Nonalphanumeric characters (e.g., !, $, #, %%)");
 128         return 1;
 129     }
 130     return 0;
 131 }
 132
 133 static int
 134 external_passwd_quality (krb5_context context,
 135                          krb5_principal principal,
 136                          krb5_data *pwd,
 137                          const char *opaque,
 138                          char *message,
 139                          size_t length)
 140 {
 141     krb5_error_code ret;
 142     const char *program;
 143     char *p;
 144     pid_t child;
 145     int status;
 146     char reply[1024];
 147     FILE *in = NULL, *out = NULL, *error = NULL;
 148
 149     if (memchr(pwd->data, '\n', pwd->length) != NULL) {
 150         snprintf(message, length, "password contains newline, "
 151                  "not valid for external test");
 152         return 1;
 153     }
 154
 155     program = krb5_config_get_string(context, NULL,
 156                                      "password_quality",
 157                                      "external_program",
 158                                      NULL);
 159     if (program == NULL) {
 160         snprintf(message, length, "external password quality "
 161                  "program not configured");
 162         return 1;
 163     }
 164
 165     ret = krb5_unparse_name(context, principal, &p);
 166     if (ret) {
 167         strlcpy(message, "out of memory", length);
 168         return 1;
 169     }
 170
 171     child = pipe_execv(&in, &out, &error, program, program, p, NULL);
 172     if (child < 0) {
 173         snprintf(message, length, "external password quality "
 174                  "program failed to execute for principal %s", p);
 175         free(p);
 176         return 1;
 177     }
 178
 179     fprintf(in, "principal: %s\n"
 180             "new-password: %.*s\n"
 181             "end\n",
 182             p, (int)pwd->length, (char *)pwd->data);
 183
 184     fclose(in);
 185
 186     if (fgets(reply, sizeof(reply), out) == NULL) {
 187
 188         if (fgets(reply, sizeof(reply), error) == NULL) {
 189             snprintf(message, length, "external password quality "
 190                      "program failed without error");
 191
 192         } else {
 193             reply[strcspn(reply, "\n")] = '\0';
 194             snprintf(message, length, "External password quality "
 195                      "program failed: %s", reply);
 196         }
 197
 198         fclose(out);
 199         fclose(error);
 200         wait_for_process(child);
 201         return 1;
 202     }
 203     reply[strcspn(reply, "\n")] = '\0';
 204
 205     fclose(out);
 206     fclose(error);
 207
 208     status = wait_for_process(child);
 209
 210     if (SE_IS_ERROR(status) || SE_PROCSTATUS(status) != 0) {
 211         snprintf(message, length, "external program failed: %s", reply);
 212         free(p);
 213         return 1;
 214     }
 215
 216     if (strcmp(reply, "APPROVED") != 0) {
 217         snprintf(message, length, "%s", reply);
 218         free(p);
 219         return 1;
 220     }
 221
 222     free(p);
 223
 224     return 0;
 225 }
 226
 227
 228 static kadm5_passwd_quality_check_func_v0 passwd_quality_check =
 229         min_length_passwd_quality_v0;
 230
 231 struct kadm5_pw_policy_check_func builtin_funcs[] = {
 232     { "minimum-length", min_length_passwd_quality },
 233     { "character-class", char_class_passwd_quality },
 234     { "external-check", external_passwd_quality },
 235     { NULL, NULL }
 236 };
 237 struct kadm5_pw_policy_verifier builtin_verifier = {
 238     "builtin",
 239     KADM5_PASSWD_VERSION_V1,
 240     "Heimdal builtin",
 241     builtin_funcs
 242 };
 243
 244 static struct kadm5_pw_policy_verifier **verifiers;
 245 static int num_verifiers;
 246
 247 /*
 248  * setup the password quality hook
 249  */
 250
 251 #ifndef RTLD_NOW
 252 #define RTLD_NOW 0
 253 #endif
 254
 255 void
 256 kadm5_setup_passwd_quality_check(krb5_context context,
 257                                  const char *check_library,
 258                                  const char *check_function)
 259 {
 260 #ifdef HAVE_DLOPEN
 261     void *handle;
 262     void *sym;
 263     int *version;
 264     const char *tmp;
 265
 266     if(check_library == NULL) {
 267         tmp = krb5_config_get_string(context, NULL,
 268                                      "password_quality",
 269                                      "check_library",
 270                                      NULL);
 271         if(tmp != NULL)
 272             check_library = tmp;
 273     }
 274     if(check_function == NULL) {
 275         tmp = krb5_config_get_string(context, NULL,
 276                                      "password_quality",
 277                                      "check_function",
 278                                      NULL);
 279         if(tmp != NULL)
 280             check_function = tmp;
 281     }
 282     if(check_library != NULL && check_function == NULL)
 283         check_function = "passwd_check";
 284
 285     if(check_library == NULL)
 286         return;
 287     handle = dlopen(check_library, RTLD_NOW);
 288     if(handle == NULL) {
 289         krb5_warnx(context, "failed to open `%s'", check_library);
 290         return;
 291     }
 292     version = (int *) dlsym(handle, "version");
 293     if(version == NULL) {
 294         krb5_warnx(context,
 295                    "didn't find `version' symbol in `%s'", check_library);
 296         dlclose(handle);
 297         return;
 298     }
 299     if(*version != KADM5_PASSWD_VERSION_V0) {
 300         krb5_warnx(context,
 301                    "version of loaded library is %d (expected %d)",
 302                    *version, KADM5_PASSWD_VERSION_V0);
 303         dlclose(handle);
 304         return;
 305     }
 306     sym = dlsym(handle, check_function);
 307     if(sym == NULL) {
 308         krb5_warnx(context,
 309                    "didn't find `%s' symbol in `%s'",
 310                    check_function, check_library);
 311         dlclose(handle);
 312         return;
 313     }
 314     passwd_quality_check = (kadm5_passwd_quality_check_func_v0) sym;
 315 #endif /* HAVE_DLOPEN */
 316 }
 317
 318 #ifdef HAVE_DLOPEN
 319
 320 static krb5_error_code
 321 add_verifier(krb5_context context, const char *check_library)
 322 {
 323     struct kadm5_pw_policy_verifier *v, **tmp;
 324     void *handle;
 325     int i;
 326
 327     handle = dlopen(check_library, RTLD_NOW);
 328     if(handle == NULL) {
 329         krb5_warnx(context, "failed to open `%s'", check_library);
 330         return ENOENT;
 331     }
 332     v = (struct kadm5_pw_policy_verifier *) dlsym(handle, "kadm5_password_verifier");
 333     if(v == NULL) {
 334         krb5_warnx(context,
 335                    "didn't find `kadm5_password_verifier' symbol "
 336                    "in `%s'", check_library);
 337         dlclose(handle);
 338         return ENOENT;
 339     }
 340     if(v->version != KADM5_PASSWD_VERSION_V1) {
 341         krb5_warnx(context,
 342                    "version of loaded library is %d (expected %d)",
 343                    v->version, KADM5_PASSWD_VERSION_V1);
 344         dlclose(handle);
 345         return EINVAL;
 346     }
 347     for (i = 0; i < num_verifiers; i++) {
 348         if (strcmp(v->name, verifiers[i]->name) == 0)
 349             break;
 350     }
 351     if (i < num_verifiers) {
 352         krb5_warnx(context, "password verifier library `%s' is already loaded",
 353                    v->name);
 354         dlclose(handle);
 355         return 0;
 356     }
 357
 358     tmp = realloc(verifiers, (num_verifiers + 1) * sizeof(*verifiers));
 359     if (tmp == NULL) {
 360         krb5_warnx(context, "out of memory");
 361         dlclose(handle);
 362         return 0;
 363     }
 364     verifiers = tmp;
 365     verifiers[num_verifiers] = v;
 366     num_verifiers++;
 367
 368     return 0;
 369 }
 370
 371 #endif
 372
 373 krb5_error_code
 374 kadm5_add_passwd_quality_verifier(krb5_context context,
 375                                   const char *check_library)
 376 {
 377 #ifdef HAVE_DLOPEN
 378
 379     if(check_library == NULL) {
 380         krb5_error_code ret;
 381         char **tmp;
 382
 383         tmp = krb5_config_get_strings(context, NULL,
 384                                       "password_quality",
 385                                       "policy_libraries",
 386                                       NULL);
 387         if(tmp == NULL || *tmp == NULL)
 388             return 0;
 389
 390         while (*tmp) {
 391             ret = add_verifier(context, *tmp);
 392             if (ret)
 393                 return ret;
 394             tmp++;
 395         }
 396         return 0;
 397     } else {
 398         return add_verifier(context, check_library);
 399     }
 400 #else
 401     return 0;
 402 #endif /* HAVE_DLOPEN */
 403 }
 404
 405 /*
 406  *
 407  */
 408
 409 static const struct kadm5_pw_policy_check_func *
 410 find_func(krb5_context context, const char *name)
 411 {
 412     const struct kadm5_pw_policy_check_func *f;
 413     char *module = NULL;
 414     const char *p, *func;
 415     int i;
 416
 417     p = strchr(name, ':');
 418     if (p) {
 419         size_t len = p - name + 1;
 420         func = p + 1;
 421         module = malloc(len);
 422         if (module == NULL)
 423             return NULL;
 424         strlcpy(module, name, len);
 425     } else
 426         func = name;
 427
 428     /* Find module in loaded modules first */
 429     for (i = 0; i < num_verifiers; i++) {
 430         if (module && strcmp(module, verifiers[i]->name) != 0)
 431             continue;
 432         for (f = verifiers[i]->funcs; f->name ; f++)
 433             if (strcmp(func, f->name) == 0) {
 434                 if (module)
 435                     free(module);
 436                 return f;
 437             }
 438     }
 439     /* Lets try try the builtin modules */
 440     if (module == NULL || strcmp(module, "builtin") == 0) {
 441         for (f = builtin_verifier.funcs; f->name ; f++)
 442             if (strcmp(func, f->name) == 0) {
 443                 if (module)
 444                     free(module);
 445                 return f;
 446             }
 447     }
 448     if (module)
 449         free(module);
 450     return NULL;
 451 }
 452
 453 const char *
 454 kadm5_check_password_quality (krb5_context context,
 455                               krb5_principal principal,
 456                               krb5_data *pwd_data)
 457 {
 458     const struct kadm5_pw_policy_check_func *proc;
 459     static char error_msg[1024];
 460     const char *msg;
 461     char **v, **vp;
 462     int ret;
 463
 464     /*
 465      * Check if we should use the old version of policy function.
 466      */
 467
 468     v = krb5_config_get_strings(context, NULL,
 469                                 "password_quality",
 470                                 "policies",
 471                                 NULL);
 472     if (v == NULL) {
 473         msg = (*passwd_quality_check) (context, principal, pwd_data);
 474         if (msg)
 475             krb5_set_error_message(context, 0, "password policy failed: %s", msg);
 476         return msg;
 477     }
 478
 479     error_msg[0] = '\0';
 480
 481     msg = NULL;
 482     for(vp = v; *vp; vp++) {
 483         proc = find_func(context, *vp);
 484         if (proc == NULL) {
 485             msg = "failed to find password verifier function";
 486             krb5_set_error_message(context, 0, "Failed to find password policy "
 487                                    "function: %s", *vp);
 488             break;
 489         }
 490         ret = (proc->func)(context, principal, pwd_data, NULL,
 491                            error_msg, sizeof(error_msg));
 492         if (ret) {
 493             krb5_set_error_message(context, 0, "Password policy "
 494                                    "%s failed with %s",
 495                                    proc->name, error_msg);
 496             msg = error_msg;
 497             break;
 498         }
 499     }
 500     krb5_config_free_strings(v);
 501
 502     /* If the default quality check isn't used, lets check that the
 503      * old quality function the user have set too */
 504     if (msg == NULL && passwd_quality_check != min_length_passwd_quality_v0) {
 505         msg = (*passwd_quality_check) (context, principal, pwd_data);
 506         if (msg)
 507             krb5_set_error_message(context, 0, "(old) password policy "
 508                                    "failed with %s", msg);
 509
 510     }
 511     return msg;
 512 }