login-utils/chfn.c

   1 /*
   2  *   chfn.c -- change your finger information
   3  *   (c) 1994 by salvatore valente <svalente@athena.mit.edu>
   4  *   (c) 2012 by Cody Maloney <cmaloney@theoreticalchaos.com>
   5  *
   6  *   this program is free software.  you can redistribute it and
   7  *   modify it under the terms of the gnu general public license.
   8  *   there is no warranty.
   9  *
  10  *   $Author: aebr $
  11  *   $Revision: 1.18 $
  12  *   $Date: 1998/06/11 22:30:11 $
  13  *
  14  * Updated Thu Oct 12 09:19:26 1995 by faith@cs.unc.edu with security
  15  * patches from Zefram <A.Main@dcs.warwick.ac.uk>
  16  *
  17  * Hacked by Peter Breitenlohner, peb@mppmu.mpg.de,
  18  * to remove trailing empty fields.  Oct 5, 96.
  19  *
  20  *  1999-02-22 Arkadiusz Miśkiewicz <misiek@pld.ORG.PL>
  21  *  - added Native Language Support
  22  */
  23
  24 #include <ctype.h>
  25 #include <errno.h>
  26 #include <getopt.h>
  27 #include <pwd.h>
  28 #include <stdbool.h>
  29 #include <stdio.h>
  30 #include <stdlib.h>
  31 #include <string.h>
  32 #include <sys/types.h>
  33 #include <unistd.h>
  34
  35 #include "c.h"
  36 #include "env.h"
  37 #include "closestream.h"
  38 #include "islocal.h"
  39 #include "nls.h"
  40 #include "setpwnam.h"
  41 #include "strutils.h"
  42 #include "xalloc.h"
  43 #include "logindefs.h"
  44
  45 #include "ch-common.h"
  46
  47 #ifdef HAVE_LIBSELINUX
  48 # include <selinux/selinux.h>
  49 # include "selinux_utils.h"
  50 #endif
  51
  52 #ifdef HAVE_LIBUSER
  53 # include <libuser/user.h>
  54 # include "libuser.h"
  55 #elif CHFN_CHSH_PASSWORD
  56 # include "auth.h"
  57 #endif
  58
  59 struct finfo {
  60         char *full_name;
  61         char *office;
  62         char *office_phone;
  63         char *home_phone;
  64         char *other;
  65 };
  66
  67 struct chfn_control {
  68         struct passwd *pw;
  69         char *username;
  70         /*  "oldf"  Contains the users original finger information.
  71          *  "newf"  Contains the changed finger information, and contains
  72          *          NULL in fields that haven't been changed.
  73          *  In the end, "newf" is folded into "oldf".  */
  74         struct finfo oldf, newf;
  75         unsigned int
  76                 allow_fullname:1,       /* The login.defs restriction */
  77                 allow_room:1,              /* see: man login.defs(5) */
  78                 allow_work:1,              /* and look for CHFN_RESTRICT */
  79                 allow_home:1,              /* keyword for these four. */
  80                 changed:1,              /* is change requested */
  81                 interactive:1;          /* whether to prompt for fields or not */
  82 };
  83
  84 /* we do not accept gecos field sizes longer than MAX_FIELD_SIZE */
  85 #define MAX_FIELD_SIZE          256
  86
  87 static void __attribute__((__noreturn__)) usage(FILE *fp)
  88 {
  89         fputs(USAGE_HEADER, fp);
  90         fprintf(fp, _(" %s [options] [<username>]\n"), program_invocation_short_name);
  91
  92         fputs(USAGE_SEPARATOR, fp);
  93         fputs(_("Change your finger information.\n"), fp);
  94
  95         fputs(USAGE_OPTIONS, fp);
  96         fputs(_(" -f, --full-name <full-name>  real name\n"), fp);
  97         fputs(_(" -o, --office <office>        office number\n"), fp);
  98         fputs(_(" -p, --office-phone <phone>   office phone number\n"), fp);
  99         fputs(_(" -h, --home-phone <phone>     home phone number\n"), fp);
 100         fputs(USAGE_SEPARATOR, fp);
 101         fputs(_(" -u, --help     display this help and exit\n"), fp);
 102         fputs(_(" -v, --version  output version information and exit\n"), fp);
 103         fprintf(fp, USAGE_MAN_TAIL("chfn(1)"));
 104         exit(fp == stderr ? EXIT_FAILURE : EXIT_SUCCESS);
 105 }
 106
 107 /*
 108  *  check_gecos_string () --
 109  *      check that the given gecos string is legal.  if it's not legal,
 110  *      output "msg" followed by a description of the problem, and return (-1).
 111  */
 112 static int check_gecos_string(const char *msg, char *gecos)
 113 {
 114         const size_t len = strlen(gecos);
 115
 116         if (MAX_FIELD_SIZE < len) {
 117                 warnx(_("field %s is too long"), msg);
 118                 return -1;
 119         }
 120         if (illegal_passwd_chars(gecos)) {
 121                 warnx(_("%s: has illegal characters"), gecos);
 122                 return -1;
 123         }
 124         return 0;
 125 }
 126
 127 /*
 128  *  parse_argv () --
 129  *      parse the command line arguments.
 130  *      returns true if no information beyond the username was given.
 131  */
 132 static void parse_argv(struct chfn_control *ctl, int argc, char **argv)
 133 {
 134         int index, c, status = 0;
 135         static const struct option long_options[] = {
 136                 {"full-name", required_argument, 0, 'f'},
 137                 {"office", required_argument, 0, 'o'},
 138                 {"office-phone", required_argument, 0, 'p'},
 139                 {"home-phone", required_argument, 0, 'h'},
 140                 {"help", no_argument, 0, 'u'},
 141                 {"version", no_argument, 0, 'v'},
 142                 {NULL, no_argument, 0, '0'},
 143         };
 144
 145         while ((c = getopt_long(argc, argv, "f:r:p:h:o:uv", long_options,
 146                                 &index)) != -1) {
 147                 switch (c) {
 148                 case 'f':
 149                         if (!ctl->allow_fullname)
 150                                 errx(EXIT_FAILURE, _("login.defs forbids setting %s"), _("Name"));
 151                         ctl->newf.full_name = optarg;
 152                         status += check_gecos_string(_("Name"), optarg);
 153                         break;
 154                 case 'o':
 155                         if (!ctl->allow_room)
 156                                 errx(EXIT_FAILURE, _("login.defs forbids setting %s"), _("Office"));
 157                         ctl->newf.office = optarg;
 158                         status += check_gecos_string(_("Office"), optarg);
 159                         break;
 160                 case 'p':
 161                         if (!ctl->allow_work)
 162                                 errx(EXIT_FAILURE, _("login.defs forbids setting %s"), _("Office Phone"));
 163                         ctl->newf.office_phone = optarg;
 164                         status += check_gecos_string(_("Office Phone"), optarg);
 165                         break;
 166                 case 'h':
 167                         if (!ctl->allow_home)
 168                                 errx(EXIT_FAILURE, _("login.defs forbids setting %s"), _("Home Phone"));
 169                         ctl->newf.home_phone = optarg;
 170                         status += check_gecos_string(_("Home Phone"), optarg);
 171                         break;
 172                 case 'v':
 173                         printf(UTIL_LINUX_VERSION);
 174                         exit(EXIT_SUCCESS);
 175                 case 'u':
 176                         usage(stdout);
 177                 default:
 178                         usage(stderr);
 179                 }
 180                 ctl->changed = 1;
 181                 ctl->interactive = 0;
 182         }
 183         if (status != 0)
 184                 exit(EXIT_FAILURE);
 185         /* done parsing arguments.  check for a username. */
 186         if (optind < argc) {
 187                 if (optind + 1 < argc)
 188                         usage(stderr);
 189                 ctl->username = argv[optind];
 190         }
 191         return;
 192 }
 193
 194 /*
 195  *  parse_passwd () --
 196  *      take a struct password and fill in the fields of the struct finfo.
 197  */
 198 static void parse_passwd(struct chfn_control *ctl)
 199 {
 200         char *gecos;
 201
 202         if (!ctl->pw)
 203                 return;
 204         /* use pw_gecos - we take a copy since PAM destroys the original */
 205         gecos = xstrdup(ctl->pw->pw_gecos);
 206         /* extract known fields */
 207         ctl->oldf.full_name = strsep(&gecos, ",");
 208         ctl->oldf.office = strsep(&gecos, ",");
 209         ctl->oldf.office_phone = strsep(&gecos, ",");
 210         ctl->oldf.home_phone = strsep(&gecos, ",");
 211         /*  extra fields contain site-specific information, and can
 212          *  not be changed by this version of chfn.  */
 213         ctl->oldf.other = strsep(&gecos, ",");
 214 }
 215
 216 /*
 217  *  ask_new_field () --
 218  *      ask the user for a given field and check that the string is legal.
 219  */
 220 static char *ask_new_field(struct chfn_control *ctl, const char *question,
 221                            char *def_val)
 222 {
 223         int len;
 224         char *ans;
 225         char buf[MAX_FIELD_SIZE + 2];
 226
 227         if (!def_val)
 228                 def_val = "";
 229         while (true) {
 230                 printf("%s [%s]: ", question, def_val);
 231                 __fpurge(stdin);
 232                 if (fgets(buf, sizeof(buf), stdin) == NULL)
 233                         errx(EXIT_FAILURE, _("Aborted."));
 234                 ans = buf;
 235                 /* remove white spaces from string end */
 236                 ltrim_whitespace((unsigned char *) ans);
 237                 len = rtrim_whitespace((unsigned char *) ans);
 238                 if (len == 0)
 239                         return xstrdup(def_val);
 240                 if (!strcasecmp(ans, "none")) {
 241                         ctl->changed = 1;
 242                         return xstrdup("");
 243                 }
 244                 if (check_gecos_string(question, ans) >= 0)
 245                         break;
 246         }
 247         ctl->changed = 1;
 248         return xstrdup(ans);
 249 }
 250
 251 /*
 252  *  get_login_defs()
 253  *      find /etc/login.defs CHFN_RESTRICT and save restrictions to run time
 254  */
 255 static void get_login_defs(struct chfn_control *ctl)
 256 {
 257         const char *s;
 258         size_t i;
 259         int broken = 0;
 260
 261         /* real root does not have restrictions */
 262         if (geteuid() == getuid() && getuid() == 0) {
 263                 ctl->allow_fullname = ctl->allow_room = ctl->allow_work = ctl->allow_home = 1;
 264                 return;
 265         }
 266         s = getlogindefs_str("CHFN_RESTRICT", "");
 267         if (!strcmp(s, "yes")) {
 268                 ctl->allow_room = ctl->allow_work = ctl->allow_home = 1;
 269                 return;
 270         }
 271         if (!strcmp(s, "no")) {
 272                 ctl->allow_fullname = ctl->allow_room = ctl->allow_work = ctl->allow_home = 1;
 273                 return;
 274         }
 275         for (i = 0; s[i]; i++) {
 276                 switch (s[i]) {
 277                 case 'f':
 278                         ctl->allow_fullname = 1;
 279                         break;
 280                 case 'r':
 281                         ctl->allow_room = 1;
 282                         break;
 283                 case 'w':
 284                         ctl->allow_work = 1;
 285                         break;
 286                 case 'h':
 287                         ctl->allow_home = 1;
 288                         break;
 289                 default:
 290                         broken = 1;
 291                 }
 292         }
 293         if (broken)
 294                 warnx(_("%s: CHFN_RESTRICT has unexpected value: %s"), _PATH_LOGINDEFS, s);
 295         if (!ctl->allow_fullname && !ctl->allow_room && !ctl->allow_work && !ctl->allow_home)
 296                 errx(EXIT_FAILURE, _("%s: CHFN_RESTRICT does not allow any changes"), _PATH_LOGINDEFS);
 297         return;
 298 }
 299
 300 /*
 301  *  ask_info () --
 302  *      prompt the user for the finger information and store it.
 303  */
 304 static void ask_info(struct chfn_control *ctl)
 305 {
 306         if (ctl->allow_fullname)
 307                 ctl->newf.full_name = ask_new_field(ctl, _("Name"), ctl->oldf.full_name);
 308         if (ctl->allow_room)
 309                 ctl->newf.office = ask_new_field(ctl, _("Office"), ctl->oldf.office);
 310         if (ctl->allow_work)
 311                 ctl->newf.office_phone = ask_new_field(ctl, _("Office Phone"), ctl->oldf.office_phone);
 312         if (ctl->allow_home)
 313                 ctl->newf.home_phone = ask_new_field(ctl, _("Home Phone"), ctl->oldf.home_phone);
 314         putchar('\n');
 315 }
 316
 317 /*
 318  *  find_field () --
 319  *      find field value in uninteractive mode; can be new, old, or blank
 320  */
 321 static char *find_field(char *nf, char *of)
 322 {
 323         if (nf)
 324                 return nf;
 325         if (of)
 326                 return of;
 327         return xstrdup("");
 328 }
 329
 330 /*
 331  *  add_missing () --
 332  *      add not supplied field values when in uninteractive mode
 333  */
 334 static void add_missing(struct chfn_control *ctl)
 335 {
 336         ctl->newf.full_name = find_field(ctl->newf.full_name, ctl->oldf.full_name);
 337         ctl->newf.office = find_field(ctl->newf.office, ctl->oldf.office);
 338         ctl->newf.office_phone = find_field(ctl->newf.office_phone, ctl->oldf.office_phone);
 339         ctl->newf.home_phone = find_field(ctl->newf.home_phone, ctl->oldf.home_phone);
 340         ctl->newf.other = find_field(ctl->newf.other, ctl->oldf.other);
 341         printf("\n");
 342 }
 343
 344 /*
 345  *  save_new_data () --
 346  *      save the given finger info in /etc/passwd.
 347  *      return zero on success.
 348  */
 349 static int save_new_data(struct chfn_control *ctl)
 350 {
 351         char *gecos;
 352         int len;
 353
 354         /* create the new gecos string */
 355         len = xasprintf(&gecos, "%s,%s,%s,%s,%s",
 356                         ctl->newf.full_name,
 357                         ctl->newf.office,
 358                         ctl->newf.office_phone,
 359                         ctl->newf.home_phone,
 360                         ctl->newf.other);
 361
 362         /* remove trailing empty fields (but not subfields of ctl->newf.other) */
 363         if (!ctl->newf.other) {
 364                 while (len > 0 && gecos[len - 1] == ',')
 365                         len--;
 366                 gecos[len] = 0;
 367         }
 368
 369 #ifdef HAVE_LIBUSER
 370         if (set_value_libuser("chfn", ctl->username, ctl->pw->pw_uid,
 371                         LU_GECOS, gecos) < 0) {
 372 #else /* HAVE_LIBUSER */
 373         /* write the new struct passwd to the passwd file. */
 374         ctl->pw->pw_gecos = gecos;
 375         if (setpwnam(ctl->pw, ".chfn") < 0) {
 376                 warn("setpwnam failed");
 377 #endif
 378                 printf(_
 379                        ("Finger information *NOT* changed.  Try again later.\n"));
 380                 return -1;
 381         }
 382         free(gecos);
 383         printf(_("Finger information changed.\n"));
 384         return 0;
 385 }
 386
 387 int main(int argc, char **argv)
 388 {
 389         uid_t uid;
 390         struct chfn_control ctl = {
 391                 .interactive = 1
 392         };
 393
 394         sanitize_env();
 395         setlocale(LC_ALL, "");  /* both for messages and for iscntrl() below */
 396         bindtextdomain(PACKAGE, LOCALEDIR);
 397         textdomain(PACKAGE);
 398         atexit(close_stdout);
 399         uid = getuid();
 400
 401         /* check /etc/login.defs CHFN_RESTRICT */
 402         get_login_defs(&ctl);
 403
 404         parse_argv(&ctl, argc, argv);
 405         if (!ctl.username) {
 406                 ctl.pw = getpwuid(uid);
 407                 if (!ctl.pw)
 408                         errx(EXIT_FAILURE, _("you (user %d) don't exist."),
 409                              uid);
 410                 ctl.username = ctl.pw->pw_name;
 411         } else {
 412                 ctl.pw = getpwnam(ctl.username);
 413                 if (!ctl.pw)
 414                         errx(EXIT_FAILURE, _("user \"%s\" does not exist."),
 415                              ctl.username);
 416         }
 417         parse_passwd(&ctl);
 418 #ifndef HAVE_LIBUSER
 419         if (!(is_local(ctl.username)))
 420                 errx(EXIT_FAILURE, _("can only change local entries"));
 421 #endif
 422
 423 #ifdef HAVE_LIBSELINUX
 424         if (is_selinux_enabled() > 0) {
 425                 if (uid == 0) {
 426                         access_vector_t av = get_access_vector("passwd", "chfn");
 427
 428                         if (selinux_check_passwd_access(av) != 0) {
 429                                 security_context_t user_context;
 430                                 if (getprevcon(&user_context) < 0)
 431                                         user_context = NULL;
 432                                 errx(EXIT_FAILURE,
 433                                      _("%s is not authorized to change "
 434                                        "the finger info of %s"),
 435                                      user_context ? : _("Unknown user context"),
 436                                      ctl.username);
 437                         }
 438                 }
 439                 if (setupDefaultContext(_PATH_PASSWD))
 440                         errx(EXIT_FAILURE,
 441                              _("can't set default context for %s"), _PATH_PASSWD);
 442         }
 443 #endif
 444
 445 #ifdef HAVE_LIBUSER
 446         /* If we're setuid and not really root, disallow the password change. */
 447         if (geteuid() != getuid() && uid != ctl.pw->pw_uid) {
 448 #else
 449         if (uid != 0 && uid != ctl.pw->pw_uid) {
 450 #endif
 451                 errno = EACCES;
 452                 err(EXIT_FAILURE, _("running UID doesn't match UID of user we're "
 453                       "altering, change denied"));
 454         }
 455
 456         printf(_("Changing finger information for %s.\n"), ctl.username);
 457
 458 #if !defined(HAVE_LIBUSER) && defined(CHFN_CHSH_PASSWORD)
 459         if (!auth_pam("chfn", uid, ctl.username)) {
 460                 return EXIT_FAILURE;
 461         }
 462 #endif
 463
 464         if (ctl.interactive)
 465                 ask_info(&ctl);
 466
 467         add_missing(&ctl);
 468
 469         if (!ctl.changed) {
 470                 printf(_("Finger information not changed.\n"));
 471                 return EXIT_SUCCESS;
 472         }
 473
 474         return save_new_data(&ctl) == 0 ? EXIT_SUCCESS : EXIT_FAILURE;
 475 }