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