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 #ifdef HAVE_LIBREADLINE
  60 # define _FUNCTION_DEF
  61 # include <readline/readline.h>
  62 #endif
  63
  64 struct finfo {
  65         char *full_name;
  66         char *office;
  67         char *office_phone;
  68         char *home_phone;
  69         char *other;
  70 };
  71
  72 struct chfn_control {
  73         struct passwd *pw;
  74         char *username;
  75         /*  "oldf"  Contains the users original finger information.
  76          *  "newf"  Contains the changed finger information, and contains
  77          *          NULL in fields that haven't been changed.
  78          *  In the end, "newf" is folded into "oldf".  */
  79         struct finfo oldf, newf;
  80         unsigned int
  81                 allow_fullname:1,       /* The login.defs restriction */
  82                 allow_room:1,              /* see: man login.defs(5) */
  83                 allow_work:1,              /* and look for CHFN_RESTRICT */
  84                 allow_home:1,              /* keyword for these four. */
  85                 changed:1,              /* is change requested */
  86                 interactive:1;          /* whether to prompt for fields or not */
  87 };
  88
  89 /* we do not accept gecos field sizes longer than MAX_FIELD_SIZE */
  90 #define MAX_FIELD_SIZE          256
  91
  92 static void __attribute__((__noreturn__)) usage(FILE *fp)
  93 {
  94         fputs(USAGE_HEADER, fp);
  95         fprintf(fp, _(" %s [options] [<username>]\n"), program_invocation_short_name);
  96
  97         fputs(USAGE_SEPARATOR, fp);
  98         fputs(_("Change your finger information.\n"), fp);
  99
 100         fputs(USAGE_OPTIONS, fp);
 101         fputs(_(" -f, --full-name <full-name>  real name\n"), fp);
 102         fputs(_(" -o, --office <office>        office number\n"), fp);
 103         fputs(_(" -p, --office-phone <phone>   office phone number\n"), fp);
 104         fputs(_(" -h, --home-phone <phone>     home phone number\n"), fp);
 105         fputs(USAGE_SEPARATOR, fp);
 106         fputs(_(" -u, --help     display this help and exit\n"), fp);
 107         fputs(_(" -v, --version  output version information and exit\n"), fp);
 108         fprintf(fp, USAGE_MAN_TAIL("chfn(1)"));
 109         exit(fp == stderr ? EXIT_FAILURE : EXIT_SUCCESS);
 110 }
 111
 112 /*
 113  *  check_gecos_string () --
 114  *      check that the given gecos string is legal.  if it's not legal,
 115  *      output "msg" followed by a description of the problem, and return (-1).
 116  */
 117 static int check_gecos_string(const char *msg, char *gecos)
 118 {
 119         const size_t len = strlen(gecos);
 120
 121         if (MAX_FIELD_SIZE < len) {
 122                 warnx(_("field %s is too long"), msg);
 123                 return -1;
 124         }
 125         if (illegal_passwd_chars(gecos)) {
 126                 warnx(_("%s: has illegal characters"), gecos);
 127                 return -1;
 128         }
 129         return 0;
 130 }
 131
 132 /*
 133  *  parse_argv () --
 134  *      parse the command line arguments.
 135  *      returns true if no information beyond the username was given.
 136  */
 137 static void parse_argv(struct chfn_control *ctl, int argc, char **argv)
 138 {
 139         int index, c, status = 0;
 140         static const struct option long_options[] = {
 141                 { "full-name",    required_argument, NULL, 'f' },
 142                 { "office",       required_argument, NULL, 'o' },
 143                 { "office-phone", required_argument, NULL, 'p' },
 144                 { "home-phone",   required_argument, NULL, 'h' },
 145                 { "help",         no_argument,       NULL, 'u' },
 146                 { "version",      no_argument,       NULL, 'v' },
 147                 { NULL, 0, NULL, 0 },
 148         };
 149
 150         while ((c = getopt_long(argc, argv, "f:r:p:h:o:uv", long_options,
 151                                 &index)) != -1) {
 152                 switch (c) {
 153                 case 'f':
 154                         if (!ctl->allow_fullname)
 155                                 errx(EXIT_FAILURE, _("login.defs forbids setting %s"), _("Name"));
 156                         ctl->newf.full_name = optarg;
 157                         status += check_gecos_string(_("Name"), optarg);
 158                         break;
 159                 case 'o':
 160                         if (!ctl->allow_room)
 161                                 errx(EXIT_FAILURE, _("login.defs forbids setting %s"), _("Office"));
 162                         ctl->newf.office = optarg;
 163                         status += check_gecos_string(_("Office"), optarg);
 164                         break;
 165                 case 'p':
 166                         if (!ctl->allow_work)
 167                                 errx(EXIT_FAILURE, _("login.defs forbids setting %s"), _("Office Phone"));
 168                         ctl->newf.office_phone = optarg;
 169                         status += check_gecos_string(_("Office Phone"), optarg);
 170                         break;
 171                 case 'h':
 172                         if (!ctl->allow_home)
 173                                 errx(EXIT_FAILURE, _("login.defs forbids setting %s"), _("Home Phone"));
 174                         ctl->newf.home_phone = optarg;
 175                         status += check_gecos_string(_("Home Phone"), optarg);
 176                         break;
 177                 case 'v':
 178                         printf(UTIL_LINUX_VERSION);
 179                         exit(EXIT_SUCCESS);
 180                 case 'u':
 181                         usage(stdout);
 182                 default:
 183                         errtryhelp(EXIT_FAILURE);
 184                 }
 185                 ctl->changed = 1;
 186                 ctl->interactive = 0;
 187         }
 188         if (status != 0)
 189                 exit(EXIT_FAILURE);
 190         /* done parsing arguments.  check for a username. */
 191         if (optind < argc) {
 192                 if (optind + 1 < argc)
 193                         usage(stderr);
 194                 ctl->username = argv[optind];
 195         }
 196         return;
 197 }
 198
 199 /*
 200  *  parse_passwd () --
 201  *      take a struct password and fill in the fields of the struct finfo.
 202  */
 203 static void parse_passwd(struct chfn_control *ctl)
 204 {
 205         char *gecos;
 206
 207         if (!ctl->pw)
 208                 return;
 209         /* use pw_gecos - we take a copy since PAM destroys the original */
 210         gecos = xstrdup(ctl->pw->pw_gecos);
 211         /* extract known fields */
 212         ctl->oldf.full_name = strsep(&gecos, ",");
 213         ctl->oldf.office = strsep(&gecos, ",");
 214         ctl->oldf.office_phone = strsep(&gecos, ",");
 215         ctl->oldf.home_phone = strsep(&gecos, ",");
 216         /*  extra fields contain site-specific information, and can
 217          *  not be changed by this version of chfn.  */
 218         ctl->oldf.other = strsep(&gecos, ",");
 219 }
 220
 221 /*
 222  *  ask_new_field () --
 223  *      ask the user for a given field and check that the string is legal.
 224  */
 225 static char *ask_new_field(struct chfn_control *ctl, const char *question,
 226                            char *def_val)
 227 {
 228         int len;
 229         char *buf;
 230 #ifndef HAVE_LIBREADLINE
 231         size_t dummy = 0;
 232 #endif
 233
 234         if (!def_val)
 235                 def_val = "";
 236         while (true) {
 237                 printf("%s [%s]: ", question, def_val);
 238                 __fpurge(stdin);
 239 #ifdef HAVE_LIBREADLINE
 240                 rl_bind_key('\t', rl_insert);
 241                 if ((buf = readline(NULL)) == NULL)
 242 #else
 243                 if (getline(&buf, &dummy, stdin) < 0)
 244 #endif
 245                         errx(EXIT_FAILURE, _("Aborted."));
 246                 /* remove white spaces from string end */
 247                 ltrim_whitespace((unsigned char *) buf);
 248                 len = rtrim_whitespace((unsigned char *) buf);
 249                 if (len == 0) {
 250                         free(buf);
 251                         return xstrdup(def_val);
 252                 }
 253                 if (!strcasecmp(buf, "none")) {
 254                         free(buf);
 255                         ctl->changed = 1;
 256                         return xstrdup("");
 257                 }
 258                 if (check_gecos_string(question, buf) >= 0)
 259                         break;
 260         }
 261         ctl->changed = 1;
 262         return buf;
 263 }
 264
 265 /*
 266  *  get_login_defs()
 267  *      find /etc/login.defs CHFN_RESTRICT and save restrictions to run time
 268  */
 269 static void get_login_defs(struct chfn_control *ctl)
 270 {
 271         const char *s;
 272         size_t i;
 273         int broken = 0;
 274
 275         /* real root does not have restrictions */
 276         if (geteuid() == getuid() && getuid() == 0) {
 277                 ctl->allow_fullname = ctl->allow_room = ctl->allow_work = ctl->allow_home = 1;
 278                 return;
 279         }
 280         s = getlogindefs_str("CHFN_RESTRICT", "");
 281         if (!strcmp(s, "yes")) {
 282                 ctl->allow_room = ctl->allow_work = ctl->allow_home = 1;
 283                 return;
 284         }
 285         if (!strcmp(s, "no")) {
 286                 ctl->allow_fullname = ctl->allow_room = ctl->allow_work = ctl->allow_home = 1;
 287                 return;
 288         }
 289         for (i = 0; s[i]; i++) {
 290                 switch (s[i]) {
 291                 case 'f':
 292                         ctl->allow_fullname = 1;
 293                         break;
 294                 case 'r':
 295                         ctl->allow_room = 1;
 296                         break;
 297                 case 'w':
 298                         ctl->allow_work = 1;
 299                         break;
 300                 case 'h':
 301                         ctl->allow_home = 1;
 302                         break;
 303                 default:
 304                         broken = 1;
 305                 }
 306         }
 307         if (broken)
 308                 warnx(_("%s: CHFN_RESTRICT has unexpected value: %s"), _PATH_LOGINDEFS, s);
 309         if (!ctl->allow_fullname && !ctl->allow_room && !ctl->allow_work && !ctl->allow_home)
 310                 errx(EXIT_FAILURE, _("%s: CHFN_RESTRICT does not allow any changes"), _PATH_LOGINDEFS);
 311         return;
 312 }
 313
 314 /*
 315  *  ask_info () --
 316  *      prompt the user for the finger information and store it.
 317  */
 318 static void ask_info(struct chfn_control *ctl)
 319 {
 320         if (ctl->allow_fullname)
 321                 ctl->newf.full_name = ask_new_field(ctl, _("Name"), ctl->oldf.full_name);
 322         if (ctl->allow_room)
 323                 ctl->newf.office = ask_new_field(ctl, _("Office"), ctl->oldf.office);
 324         if (ctl->allow_work)
 325                 ctl->newf.office_phone = ask_new_field(ctl, _("Office Phone"), ctl->oldf.office_phone);
 326         if (ctl->allow_home)
 327                 ctl->newf.home_phone = ask_new_field(ctl, _("Home Phone"), ctl->oldf.home_phone);
 328         putchar('\n');
 329 }
 330
 331 /*
 332  *  find_field () --
 333  *      find field value in uninteractive mode; can be new, old, or blank
 334  */
 335 static char *find_field(char *nf, char *of)
 336 {
 337         if (nf)
 338                 return nf;
 339         if (of)
 340                 return of;
 341         return xstrdup("");
 342 }
 343
 344 /*
 345  *  add_missing () --
 346  *      add not supplied field values when in uninteractive mode
 347  */
 348 static void add_missing(struct chfn_control *ctl)
 349 {
 350         ctl->newf.full_name = find_field(ctl->newf.full_name, ctl->oldf.full_name);
 351         ctl->newf.office = find_field(ctl->newf.office, ctl->oldf.office);
 352         ctl->newf.office_phone = find_field(ctl->newf.office_phone, ctl->oldf.office_phone);
 353         ctl->newf.home_phone = find_field(ctl->newf.home_phone, ctl->oldf.home_phone);
 354         ctl->newf.other = find_field(ctl->newf.other, ctl->oldf.other);
 355         printf("\n");
 356 }
 357
 358 /*
 359  *  save_new_data () --
 360  *      save the given finger info in /etc/passwd.
 361  *      return zero on success.
 362  */
 363 static int save_new_data(struct chfn_control *ctl)
 364 {
 365         char *gecos;
 366         int len;
 367
 368         /* create the new gecos string */
 369         len = xasprintf(&gecos, "%s,%s,%s,%s,%s",
 370                         ctl->newf.full_name,
 371                         ctl->newf.office,
 372                         ctl->newf.office_phone,
 373                         ctl->newf.home_phone,
 374                         ctl->newf.other);
 375
 376         /* remove trailing empty fields (but not subfields of ctl->newf.other) */
 377         if (!ctl->newf.other) {
 378                 while (len > 0 && gecos[len - 1] == ',')
 379                         len--;
 380                 gecos[len] = 0;
 381         }
 382
 383 #ifdef HAVE_LIBUSER
 384         if (set_value_libuser("chfn", ctl->username, ctl->pw->pw_uid,
 385                         LU_GECOS, gecos) < 0) {
 386 #else /* HAVE_LIBUSER */
 387         /* write the new struct passwd to the passwd file. */
 388         ctl->pw->pw_gecos = gecos;
 389         if (setpwnam(ctl->pw, ".chfn") < 0) {
 390                 warn("setpwnam failed");
 391 #endif
 392                 printf(_
 393                        ("Finger information *NOT* changed.  Try again later.\n"));
 394                 return -1;
 395         }
 396         free(gecos);
 397         printf(_("Finger information changed.\n"));
 398         return 0;
 399 }
 400
 401 int main(int argc, char **argv)
 402 {
 403         uid_t uid;
 404         struct chfn_control ctl = {
 405                 .interactive = 1
 406         };
 407
 408         sanitize_env();
 409         setlocale(LC_ALL, "");  /* both for messages and for iscntrl() below */
 410         bindtextdomain(PACKAGE, LOCALEDIR);
 411         textdomain(PACKAGE);
 412         atexit(close_stdout);
 413         uid = getuid();
 414
 415         /* check /etc/login.defs CHFN_RESTRICT */
 416         get_login_defs(&ctl);
 417
 418         parse_argv(&ctl, argc, argv);
 419         if (!ctl.username) {
 420                 ctl.pw = getpwuid(uid);
 421                 if (!ctl.pw)
 422                         errx(EXIT_FAILURE, _("you (user %d) don't exist."),
 423                              uid);
 424                 ctl.username = ctl.pw->pw_name;
 425         } else {
 426                 ctl.pw = getpwnam(ctl.username);
 427                 if (!ctl.pw)
 428                         errx(EXIT_FAILURE, _("user \"%s\" does not exist."),
 429                              ctl.username);
 430         }
 431         parse_passwd(&ctl);
 432 #ifndef HAVE_LIBUSER
 433         if (!(is_local(ctl.username)))
 434                 errx(EXIT_FAILURE, _("can only change local entries"));
 435 #endif
 436
 437 #ifdef HAVE_LIBSELINUX
 438         if (is_selinux_enabled() > 0) {
 439                 if (uid == 0) {
 440                         access_vector_t av = get_access_vector("passwd", "chfn");
 441
 442                         if (selinux_check_passwd_access(av) != 0) {
 443                                 security_context_t user_context;
 444                                 if (getprevcon(&user_context) < 0)
 445                                         user_context = NULL;
 446                                 errx(EXIT_FAILURE,
 447                                      _("%s is not authorized to change "
 448                                        "the finger info of %s"),
 449                                      user_context ? : _("Unknown user context"),
 450                                      ctl.username);
 451                         }
 452                 }
 453                 if (setupDefaultContext(_PATH_PASSWD))
 454                         errx(EXIT_FAILURE,
 455                              _("can't set default context for %s"), _PATH_PASSWD);
 456         }
 457 #endif
 458
 459 #ifdef HAVE_LIBUSER
 460         /* If we're setuid and not really root, disallow the password change. */
 461         if (geteuid() != getuid() && uid != ctl.pw->pw_uid) {
 462 #else
 463         if (uid != 0 && uid != ctl.pw->pw_uid) {
 464 #endif
 465                 errno = EACCES;
 466                 err(EXIT_FAILURE, _("running UID doesn't match UID of user we're "
 467                       "altering, change denied"));
 468         }
 469
 470         printf(_("Changing finger information for %s.\n"), ctl.username);
 471
 472 #if !defined(HAVE_LIBUSER) && defined(CHFN_CHSH_PASSWORD)
 473         if (!auth_pam("chfn", uid, ctl.username)) {
 474                 return EXIT_FAILURE;
 475         }
 476 #endif
 477
 478         if (ctl.interactive)
 479                 ask_info(&ctl);
 480
 481         add_missing(&ctl);
 482
 483         if (!ctl.changed) {
 484                 printf(_("Finger information not changed.\n"));
 485                 return EXIT_SUCCESS;
 486         }
 487
 488         return save_new_data(&ctl) == 0 ? EXIT_SUCCESS : EXIT_FAILURE;
 489 }