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 i, counter = 0, req_classes;
  99     size_t 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, pwd->length, '\n') != 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, 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         waitpid(child, &status, 0);
 203         return 1;
 204     }
 205     reply[strcspn(reply, "\n")] = '\0';
 206
 207     fclose(out);
 208     fclose(error);
 209
 210     if (waitpid(child, &status, 0) < 0) {
 211         snprintf(message, length, "external program failed: %s", reply);
 212         free(p);
 213         return 1;
 214     }
 215     if (!WIFEXITED(status) || WEXITSTATUS(status) != 0) {
 216         snprintf(message, length, "external program failed: %s", reply);
 217         free(p);
 218         return 1;
 219     }
 220
 221     if (strcmp(reply, "APPROVED") != 0) {
 222         snprintf(message, length, "%s", reply);
 223         free(p);
 224         return 1;
 225     }
 226
 227     free(p);
 228
 229     return 0;
 230 }
 231
 232
 233 static kadm5_passwd_quality_check_func_v0 passwd_quality_check =
 234         min_length_passwd_quality_v0;
 235
 236 struct kadm5_pw_policy_check_func builtin_funcs[] = {
 237     { "minimum-length", min_length_passwd_quality },
 238     { "character-class", char_class_passwd_quality },
 239     { "external-check", external_passwd_quality },
 240     { NULL }
 241 };
 242 struct kadm5_pw_policy_verifier builtin_verifier = {
 243     "builtin",
 244     KADM5_PASSWD_VERSION_V1,
 245     "Heimdal builtin",
 246     builtin_funcs
 247 };
 248
 249 static struct kadm5_pw_policy_verifier **verifiers;
 250 static int num_verifiers;
 251
 252 /*
 253  * setup the password quality hook
 254  */
 255
 256 #ifndef RTLD_NOW
 257 #define RTLD_NOW 0
 258 #endif
 259
 260 void
 261 kadm5_setup_passwd_quality_check(krb5_context context,
 262                                  const char *check_library,
 263                                  const char *check_function)
 264 {
 265 #ifdef HAVE_DLOPEN
 266     void *handle;
 267     void *sym;
 268     int *version;
 269     const char *tmp;
 270
 271     if(check_library == NULL) {
 272         tmp = krb5_config_get_string(context, NULL,
 273                                      "password_quality",
 274                                      "check_library",
 275                                      NULL);
 276         if(tmp != NULL)
 277             check_library = tmp;
 278     }
 279     if(check_function == NULL) {
 280         tmp = krb5_config_get_string(context, NULL,
 281                                      "password_quality",
 282                                      "check_function",
 283                                      NULL);
 284         if(tmp != NULL)
 285             check_function = tmp;
 286     }
 287     if(check_library != NULL && check_function == NULL)
 288         check_function = "passwd_check";
 289
 290     if(check_library == NULL)
 291         return;
 292     handle = dlopen(check_library, RTLD_NOW);
 293     if(handle == NULL) {
 294         krb5_warnx(context, "failed to open `%s'", check_library);
 295         return;
 296     }
 297     version = dlsym(handle, "version");
 298     if(version == NULL) {
 299         krb5_warnx(context,
 300                    "didn't find `version' symbol in `%s'", check_library);
 301         dlclose(handle);
 302         return;
 303     }
 304     if(*version != KADM5_PASSWD_VERSION_V0) {
 305         krb5_warnx(context,
 306                    "version of loaded library is %d (expected %d)",
 307                    *version, KADM5_PASSWD_VERSION_V0);
 308         dlclose(handle);
 309         return;
 310     }
 311     sym = dlsym(handle, check_function);
 312     if(sym == NULL) {
 313         krb5_warnx(context,
 314                    "didn't find `%s' symbol in `%s'",
 315                    check_function, check_library);
 316         dlclose(handle);
 317         return;
 318     }
 319     passwd_quality_check = (kadm5_passwd_quality_check_func_v0) sym;
 320 #endif /* HAVE_DLOPEN */
 321 }
 322
 323 #ifdef HAVE_DLOPEN
 324
 325 static krb5_error_code
 326 add_verifier(krb5_context context, const char *check_library)
 327 {
 328     struct kadm5_pw_policy_verifier *v, **tmp;
 329     void *handle;
 330     int i;
 331
 332     handle = dlopen(check_library, RTLD_NOW);
 333     if(handle == NULL) {
 334         krb5_warnx(context, "failed to open `%s'", check_library);
 335         return ENOENT;
 336     }
 337     v = dlsym(handle, "kadm5_password_verifier");
 338     if(v == NULL) {
 339         krb5_warnx(context,
 340                    "didn't find `kadm5_password_verifier' symbol "
 341                    "in `%s'", check_library);
 342         dlclose(handle);
 343         return ENOENT;
 344     }
 345     if(v->version != KADM5_PASSWD_VERSION_V1) {
 346         krb5_warnx(context,
 347                    "version of loaded library is %d (expected %d)",
 348                    v->version, KADM5_PASSWD_VERSION_V1);
 349         dlclose(handle);
 350         return EINVAL;
 351     }
 352     for (i = 0; i < num_verifiers; i++) {
 353         if (strcmp(v->name, verifiers[i]->name) == 0)
 354             break;
 355     }
 356     if (i < num_verifiers) {
 357         krb5_warnx(context, "password verifier library `%s' is already loaded",
 358                    v->name);
 359         dlclose(handle);
 360         return 0;
 361     }
 362
 363     tmp = realloc(verifiers, (num_verifiers + 1) * sizeof(*verifiers));
 364     if (tmp == NULL) {
 365         krb5_warnx(context, "out of memory");
 366         dlclose(handle);
 367         return 0;
 368     }
 369     verifiers = tmp;
 370     verifiers[num_verifiers] = v;
 371     num_verifiers++;
 372
 373     return 0;
 374 }
 375
 376 #endif
 377
 378 krb5_error_code
 379 kadm5_add_passwd_quality_verifier(krb5_context context,
 380                                   const char *check_library)
 381 {
 382 #ifdef HAVE_DLOPEN
 383
 384     if(check_library == NULL) {
 385         krb5_error_code ret;
 386         char **tmp;
 387
 388         tmp = krb5_config_get_strings(context, NULL,
 389                                       "password_quality",
 390                                       "policy_libraries",
 391                                       NULL);
 392         if(tmp == NULL)
 393             return 0;
 394
 395         while(tmp) {
 396             ret = add_verifier(context, *tmp);
 397             if (ret)
 398                 return ret;
 399             tmp++;
 400         }
 401     }
 402     return add_verifier(context, check_library);
 403 #else
 404     return 0;
 405 #endif /* HAVE_DLOPEN */
 406 }
 407
 408 /*
 409  *
 410  */
 411
 412 static const struct kadm5_pw_policy_check_func *
 413 find_func(krb5_context context, const char *name)
 414 {
 415     const struct kadm5_pw_policy_check_func *f;
 416     char *module = NULL;
 417     const char *p, *func;
 418     int i;
 419
 420     p = strchr(name, ':');
 421     if (p) {
 422         size_t len = p - name + 1;
 423         func = p + 1;
 424         module = malloc(len);
 425         if (module == NULL)
 426             return NULL;
 427         strlcpy(module, name, len);
 428     } else
 429         func = name;
 430
 431     /* Find module in loaded modules first */
 432     for (i = 0; i < num_verifiers; i++) {
 433         if (module && strcmp(module, verifiers[i]->name) != 0)
 434             continue;
 435         for (f = verifiers[i]->funcs; f->name ; f++)
 436             if (strcmp(name, f->name) == 0) {
 437                 if (module)
 438                     free(module);
 439                 return f;
 440             }
 441     }
 442     /* Lets try try the builtin modules */
 443     if (module == NULL || strcmp(module, "builtin") == 0) {
 444         for (f = builtin_verifier.funcs; f->name ; f++)
 445             if (strcmp(func, f->name) == 0) {
 446                 if (module)
 447                     free(module);
 448                 return f;
 449             }
 450     }
 451     if (module)
 452         free(module);
 453     return NULL;
 454 }
 455
 456 const char *
 457 kadm5_check_password_quality (krb5_context context,
 458                               krb5_principal principal,
 459                               krb5_data *pwd_data)
 460 {
 461     const struct kadm5_pw_policy_check_func *proc;
 462     static char error_msg[1024];
 463     const char *msg;
 464     char **v, **vp;
 465     int ret;
 466
 467     /*
 468      * Check if we should use the old version of policy function.
 469      */
 470
 471     v = krb5_config_get_strings(context, NULL,
 472                                 "password_quality",
 473                                 "policies",
 474                                 NULL);
 475     if (v == NULL) {
 476         msg = (*passwd_quality_check) (context, principal, pwd_data);
 477         krb5_set_error_message(context, 0, "password policy failed: %s", msg);
 478         return msg;
 479     }
 480
 481     error_msg[0] = '\0';
 482
 483     msg = NULL;
 484     for(vp = v; *vp; vp++) {
 485         proc = find_func(context, *vp);
 486         if (proc == NULL) {
 487             msg = "failed to find password verifier function";
 488             krb5_set_error_message(context, 0, "Failed to find password policy "
 489                                    "function: %s", *vp);
 490             break;
 491         }
 492         ret = (proc->func)(context, principal, pwd_data, NULL,
 493                            error_msg, sizeof(error_msg));
 494         if (ret) {
 495             krb5_set_error_message(context, 0, "Password policy "
 496                                    "%s failed with %s",
 497                                    proc->name, error_msg);
 498             msg = error_msg;
 499             break;
 500         }
 501     }
 502     krb5_config_free_strings(v);
 503
 504     /* If the default quality check isn't used, lets check that the
 505      * old quality function the user have set too */
 506     if (msg == NULL && passwd_quality_check != min_length_passwd_quality_v0) {
 507         msg = (*passwd_quality_check) (context, principal, pwd_data);
 508         if (msg)
 509             krb5_set_error_message(context, 0, "(old) password policy "
 510                                    "failed with %s", msg);
 511
 512     }
 513     return msg;
 514 }