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 RCSID("$Id$");
  38
  39 #ifdef HAVE_SYS_WAIT_H
  40 #include <sys/wait.h>
  41 #endif
  42 #ifdef HAVE_DLFCN_H
  43 #include <dlfcn.h>
  44 #endif
  45
  46 static int
  47 min_length_passwd_quality (krb5_context context,
  48                            krb5_principal principal,
  49                            krb5_data *pwd,
  50                            const char *opaque,
  51                            char *message,
  52                            size_t length)
  53 {
  54     uint32_t min_length = krb5_config_get_int_default(context, NULL, 6,
  55                                                       "password_quality",
  56                                                       "min_length",
  57                                                       NULL);
  58
  59     if (pwd->length < min_length) {
  60         strlcpy(message, "Password too short", length);
  61         return 1;
  62     } else
  63         return 0;
  64 }
  65
  66 static const char *
  67 min_length_passwd_quality_v0 (krb5_context context,
  68                               krb5_principal principal,
  69                               krb5_data *pwd)
  70 {
  71     static char message[1024];
  72     int ret;
  73
  74     message[0] = '\0';
  75
  76     ret = min_length_passwd_quality(context, principal, pwd, NULL,
  77                                     message, sizeof(message));
  78     if (ret)
  79         return message;
  80     return NULL;
  81 }
  82
  83
  84 static int
  85 char_class_passwd_quality (krb5_context context,
  86                            krb5_principal principal,
  87                            krb5_data *pwd,
  88                            const char *opaque,
  89                            char *message,
  90                            size_t length)
  91 {
  92     const char *classes[] = {
  93         "ABCDEFGHIJKLMNOPQRSTUVWXYZ",
  94         "abcdefghijklmnopqrstuvwxyz",
  95         "1234567890",
  96         "!@#$%^&*()/?<>,.{[]}\\|'~`\" "
  97     };
  98     int counter = 0, req_classes;
  99     size_t i, len;
 100     char *pw;
 101
 102     req_classes = krb5_config_get_int_default(context, NULL, 3,
 103                                               "password_quality",
 104                                               "min_classes",
 105                                               NULL);
 106
 107     len = pwd->length + 1;
 108     pw = malloc(len);
 109     if (pw == NULL) {
 110         strlcpy(message, "out of memory", length);
 111         return 1;
 112     }
 113     strlcpy(pw, pwd->data, len);
 114     len = strlen(pw);
 115
 116     for (i = 0; i < sizeof(classes)/sizeof(classes[0]); i++) {
 117         if (strcspn(pw, classes[i]) < len)
 118             counter++;
 119     }
 120     memset(pw, 0, pwd->length + 1);
 121     free(pw);
 122     if (counter < req_classes) {
 123         snprintf(message, length,
 124             "Password doesn't meet complexity requirement.\n"
 125             "Add more characters from the following classes:\n"
 126             "1. English uppercase characters (A through Z)\n"
 127             "2. English lowercase characters (a through z)\n"
 128             "3. Base 10 digits (0 through 9)\n"
 129             "4. Nonalphanumeric characters (e.g., !, $, #, %%)");
 130         return 1;
 131     }
 132     return 0;
 133 }
 134
 135 static int
 136 external_passwd_quality (krb5_context context,
 137                          krb5_principal principal,
 138                          krb5_data *pwd,
 139                          const char *opaque,
 140                          char *message,
 141                          size_t length)
 142 {
 143     krb5_error_code ret;
 144     const char *program;
 145     char *p;
 146     pid_t child;
 147     int status;
 148     char reply[1024];
 149     FILE *in = NULL, *out = NULL, *error = NULL;
 150
 151     if (memchr(pwd->data, '\n', pwd->length) != NULL) {
 152         snprintf(message, length, "password contains newline, "
 153                  "not valid for external test");
 154         return 1;
 155     }
 156
 157     program = krb5_config_get_string(context, NULL,
 158                                      "password_quality",
 159                                      "external_program",
 160                                      NULL);
 161     if (program == NULL) {
 162         snprintf(message, length, "external password quality "
 163                  "program not configured");
 164         return 1;
 165     }
 166
 167     ret = krb5_unparse_name(context, principal, &p);
 168     if (ret) {
 169         strlcpy(message, "out of memory", length);
 170         return 1;
 171     }
 172
 173     child = pipe_execv(&in, &out, &error, program, program, p, NULL);
 174     if (child < 0) {
 175         snprintf(message, length, "external password quality "
 176                  "program failed to execute for principal %s", p);
 177         free(p);
 178         return 1;
 179     }
 180
 181     fprintf(in, "principal: %s\n"
 182             "new-password: %.*s\n"
 183             "end\n",
 184             p, (int)pwd->length, (char *)pwd->data);
 185
 186     fclose(in);
 187
 188     if (fgets(reply, sizeof(reply), out) == NULL) {
 189
 190         if (fgets(reply, sizeof(reply), error) == NULL) {
 191             snprintf(message, length, "external password quality "
 192                      "program failed without error");
 193
 194         } else {
 195             reply[strcspn(reply, "\n")] = '\0';
 196             snprintf(message, length, "External password quality "
 197                      "program failed: %s", reply);
 198         }
 199
 200         fclose(out);
 201         fclose(error);
 202         wait_for_process(child);
 203         return 1;
 204     }
 205     reply[strcspn(reply, "\n")] = '\0';
 206
 207     fclose(out);
 208     fclose(error);
 209
 210     status = wait_for_process(child);
 211
 212     if (SE_IS_ERROR(status) || SE_PROCSTATUS(status) != 0) {
 213         snprintf(message, length, "external program failed: %s", reply);
 214         free(p);
 215         return 1;
 216     }
 217
 218     if (strcmp(reply, "APPROVED") != 0) {
 219         snprintf(message, length, "%s", reply);
 220         free(p);
 221         return 1;
 222     }
 223
 224     free(p);
 225
 226     return 0;
 227 }
 228
 229
 230 static kadm5_passwd_quality_check_func_v0 passwd_quality_check =
 231         min_length_passwd_quality_v0;
 232
 233 struct kadm5_pw_policy_check_func builtin_funcs[] = {
 234     { "minimum-length", min_length_passwd_quality },
 235     { "character-class", char_class_passwd_quality },
 236     { "external-check", external_passwd_quality },
 237     { NULL, NULL }
 238 };
 239 struct kadm5_pw_policy_verifier builtin_verifier = {
 240     "builtin",
 241     KADM5_PASSWD_VERSION_V1,
 242     "Heimdal builtin",
 243     builtin_funcs
 244 };
 245
 246 static struct kadm5_pw_policy_verifier **verifiers;
 247 static int num_verifiers;
 248
 249 /*
 250  * setup the password quality hook
 251  */
 252
 253 #ifndef RTLD_NOW
 254 #define RTLD_NOW 0
 255 #endif
 256
 257 void
 258 kadm5_setup_passwd_quality_check(krb5_context context,
 259                                  const char *check_library,
 260                                  const char *check_function)
 261 {
 262 #ifdef HAVE_DLOPEN
 263     void *handle;
 264     void *sym;
 265     int *version;
 266     const char *tmp;
 267
 268     if(check_library == NULL) {
 269         tmp = krb5_config_get_string(context, NULL,
 270                                      "password_quality",
 271                                      "check_library",
 272                                      NULL);
 273         if(tmp != NULL)
 274             check_library = tmp;
 275     }
 276     if(check_function == NULL) {
 277         tmp = krb5_config_get_string(context, NULL,
 278                                      "password_quality",
 279                                      "check_function",
 280                                      NULL);
 281         if(tmp != NULL)
 282             check_function = tmp;
 283     }
 284     if(check_library != NULL && check_function == NULL)
 285         check_function = "passwd_check";
 286
 287     if(check_library == NULL)
 288         return;
 289     handle = dlopen(check_library, RTLD_NOW);
 290     if(handle == NULL) {
 291         krb5_warnx(context, "failed to open `%s'", check_library);
 292         return;
 293     }
 294     version = (int *) dlsym(handle, "version");
 295     if(version == NULL) {
 296         krb5_warnx(context,
 297                    "didn't find `version' symbol in `%s'", check_library);
 298         dlclose(handle);
 299         return;
 300     }
 301     if(*version != KADM5_PASSWD_VERSION_V0) {
 302         krb5_warnx(context,
 303                    "version of loaded library is %d (expected %d)",
 304                    *version, KADM5_PASSWD_VERSION_V0);
 305         dlclose(handle);
 306         return;
 307     }
 308     sym = dlsym(handle, check_function);
 309     if(sym == NULL) {
 310         krb5_warnx(context,
 311                    "didn't find `%s' symbol in `%s'",
 312                    check_function, check_library);
 313         dlclose(handle);
 314         return;
 315     }
 316     passwd_quality_check = (kadm5_passwd_quality_check_func_v0) sym;
 317 #endif /* HAVE_DLOPEN */
 318 }
 319
 320 #ifdef HAVE_DLOPEN
 321
 322 static krb5_error_code
 323 add_verifier(krb5_context context, const char *check_library)
 324 {
 325     struct kadm5_pw_policy_verifier *v, **tmp;
 326     void *handle;
 327     int i;
 328
 329     handle = dlopen(check_library, RTLD_NOW);
 330     if(handle == NULL) {
 331         krb5_warnx(context, "failed to open `%s'", check_library);
 332         return ENOENT;
 333     }
 334     v = (struct kadm5_pw_policy_verifier *) dlsym(handle, "kadm5_password_verifier");
 335     if(v == NULL) {
 336         krb5_warnx(context,
 337                    "didn't find `kadm5_password_verifier' symbol "
 338                    "in `%s'", check_library);
 339         dlclose(handle);
 340         return ENOENT;
 341     }
 342     if(v->version != KADM5_PASSWD_VERSION_V1) {
 343         krb5_warnx(context,
 344                    "version of loaded library is %d (expected %d)",
 345                    v->version, KADM5_PASSWD_VERSION_V1);
 346         dlclose(handle);
 347         return EINVAL;
 348     }
 349     for (i = 0; i < num_verifiers; i++) {
 350         if (strcmp(v->name, verifiers[i]->name) == 0)
 351             break;
 352     }
 353     if (i < num_verifiers) {
 354         krb5_warnx(context, "password verifier library `%s' is already loaded",
 355                    v->name);
 356         dlclose(handle);
 357         return 0;
 358     }
 359
 360     tmp = realloc(verifiers, (num_verifiers + 1) * sizeof(*verifiers));
 361     if (tmp == NULL) {
 362         krb5_warnx(context, "out of memory");
 363         dlclose(handle);
 364         return 0;
 365     }
 366     verifiers = tmp;
 367     verifiers[num_verifiers] = v;
 368     num_verifiers++;
 369
 370     return 0;
 371 }
 372
 373 #endif
 374
 375 krb5_error_code
 376 kadm5_add_passwd_quality_verifier(krb5_context context,
 377                                   const char *check_library)
 378 {
 379 #ifdef HAVE_DLOPEN
 380
 381     if(check_library == NULL) {
 382         krb5_error_code ret;
 383         char **tmp;
 384
 385         tmp = krb5_config_get_strings(context, NULL,
 386                                       "password_quality",
 387                                       "policy_libraries",
 388                                       NULL);
 389         if(tmp == NULL || *tmp == NULL)
 390             return 0;
 391
 392         while (*tmp) {
 393             ret = add_verifier(context, *tmp);
 394             if (ret)
 395                 return ret;
 396             tmp++;
 397         }
 398         return 0;
 399     } else {
 400         return add_verifier(context, check_library);
 401     }
 402 #else
 403     return 0;
 404 #endif /* HAVE_DLOPEN */
 405 }
 406
 407 /*
 408  *
 409  */
 410
 411 static const struct kadm5_pw_policy_check_func *
 412 find_func(krb5_context context, const char *name)
 413 {
 414     const struct kadm5_pw_policy_check_func *f;
 415     char *module = NULL;
 416     const char *p, *func;
 417     int i;
 418
 419     p = strchr(name, ':');
 420     if (p) {
 421         size_t len = p - name + 1;
 422         func = p + 1;
 423         module = malloc(len);
 424         if (module == NULL)
 425             return NULL;
 426         strlcpy(module, name, len);
 427     } else
 428         func = name;
 429
 430     /* Find module in loaded modules first */
 431     for (i = 0; i < num_verifiers; i++) {
 432         if (module && strcmp(module, verifiers[i]->name) != 0)
 433             continue;
 434         for (f = verifiers[i]->funcs; f->name ; f++)
 435             if (strcmp(func, f->name) == 0) {
 436                 if (module)
 437                     free(module);
 438                 return f;
 439             }
 440     }
 441     /* Lets try try the builtin modules */
 442     if (module == NULL || strcmp(module, "builtin") == 0) {
 443         for (f = builtin_verifier.funcs; f->name ; f++)
 444             if (strcmp(func, f->name) == 0) {
 445                 if (module)
 446                     free(module);
 447                 return f;
 448             }
 449     }
 450     if (module)
 451         free(module);
 452     return NULL;
 453 }
 454
 455 const char *
 456 kadm5_check_password_quality (krb5_context context,
 457                               krb5_principal principal,
 458                               krb5_data *pwd_data)
 459 {
 460     const struct kadm5_pw_policy_check_func *proc;
 461     static char error_msg[1024];
 462     const char *msg;
 463     char **v, **vp;
 464     int ret;
 465
 466     /*
 467      * Check if we should use the old version of policy function.
 468      */
 469
 470     v = krb5_config_get_strings(context, NULL,
 471                                 "password_quality",
 472                                 "policies",
 473                                 NULL);
 474     if (v == NULL) {
 475         msg = (*passwd_quality_check) (context, principal, pwd_data);
 476         krb5_set_error_message(context, 0, "password policy failed: %s", msg);
 477         return msg;
 478     }
 479
 480     error_msg[0] = '\0';
 481
 482     msg = NULL;
 483     for(vp = v; *vp; vp++) {
 484         proc = find_func(context, *vp);
 485         if (proc == NULL) {
 486             msg = "failed to find password verifier function";
 487             krb5_set_error_message(context, 0, "Failed to find password policy "
 488                                    "function: %s", *vp);
 489             break;
 490         }
 491         ret = (proc->func)(context, principal, pwd_data, NULL,
 492                            error_msg, sizeof(error_msg));
 493         if (ret) {
 494             krb5_set_error_message(context, 0, "Password policy "
 495                                    "%s failed with %s",
 496                                    proc->name, error_msg);
 497             msg = error_msg;
 498             break;
 499         }
 500     }
 501     krb5_config_free_strings(v);
 502
 503     /* If the default quality check isn't used, lets check that the
 504      * old quality function the user have set too */
 505     if (msg == NULL && passwd_quality_check != min_length_passwd_quality_v0) {
 506         msg = (*passwd_quality_check) (context, principal, pwd_data);
 507         if (msg)
 508             krb5_set_error_message(context, 0, "(old) password policy "
 509                                    "failed with %s", msg);
 510
 511     }
 512     return msg;
 513 }