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chfn.c

/*
 * Copyright 1989 - 1994, Julianne Frances Haugh
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of Julianne F. Haugh nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY JULIE HAUGH AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL JULIE HAUGH OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#include <config.h>

#include "rcsid.h"
RCSID (PKG_VER "$Id: chfn.c 6 2005-03-20 15:34:28Z bubulle $")
#include <sys/types.h>
#include <stdio.h>
#include <fcntl.h>
#include <signal.h>
#include "prototypes.h"
#include "defines.h"
#include <pwd.h>
#include "pwio.h"
#include "getdef.h"
#include "pwauth.h"
#ifdef HAVE_SHADOW_H
#include <shadow.h>
#endif
#ifdef USE_PAM
#include "pam_defs.h"
#endif
/*
 * Global variables.
 */
static char *Prog;
static char fullnm[BUFSIZ];
static char roomno[BUFSIZ];
static char workph[BUFSIZ];
static char homeph[BUFSIZ];
static char slop[BUFSIZ];
static int amroot;

/*
 * External identifiers
 */

#ifdef      NDBM
extern int pw_dbm_mode;
#endif

/* local function prototypes */
static void usage (void);
static int may_change_field (int);
static void new_fields (void);
static char *copy_field (char *, char *, char *);

/*
 * usage - print command line syntax and exit
 */

static void usage (void)
{
      if (amroot)
            fprintf (stderr,
                   _("Usage: %s [-f full_name] [-r room_no] "
                     "[-w work_ph]\n"
                     "\t[-h home_ph] [-o other] [user]\n"), Prog);
      else
            fprintf (stderr,
                   _("Usage: %s [-f full_name] [-r room_no] "
                     "[-w work_ph] [-h home_ph]\n"), Prog);
      exit (1);
}


static int may_change_field (int field)
{
      const char *cp;

      /*
       * CHFN_RESTRICT can now specify exactly which fields may be changed
       * by regular users, by using any combination of the following
       * letters:
       *  f - full name
       *  r - room number
       *  w - work phone
       *  h - home phone
       *
       * This makes it possible to disallow changing the room number
       * information, for example - this feature was suggested by Maciej
       * 'Tycoon' Majchrowski.
       *
       * For backward compatibility, "yes" is equivalent to "rwh",
       * "no" is equivalent to "frwh". Only root can change anything
       * if the string is empty or not defined at all.
       */
      if (amroot)
            return 1;
      cp = getdef_str ("CHFN_RESTRICT");
      if (!cp)
            cp = "";
      else if (strcmp (cp, "yes") == 0)
            cp = "rwh";
      else if (strcmp (cp, "no") == 0)
            cp = "frwh";
      if (strchr (cp, field))
            return 1;
      return 0;
}

/*
 * new_fields - change the user's GECOS information interactively
 *
 * prompt the user for each of the four fields and fill in the fields from
 * the user's response, or leave alone if nothing was entered.
 */

static void new_fields (void)
{
      printf (_
            ("Enter the new value, or press ENTER for the default\n"));

      if (may_change_field ('f'))
            change_field (fullnm, sizeof fullnm, _("Full Name"));
      else
            printf (_("\tFull Name: %s\n"), fullnm);

      if (may_change_field ('r'))
            change_field (roomno, sizeof roomno, _("Room Number"));
      else
            printf (_("\tRoom Number: %s\n"), roomno);

      if (may_change_field ('w'))
            change_field (workph, sizeof workph, _("Work Phone"));
      else
            printf (_("\tWork Phone: %s\n"), workph);

      if (may_change_field ('h'))
            change_field (homeph, sizeof homeph, _("Home Phone"));
      else
            printf (_("\tHome Phone: %s\n"), homeph);

      if (amroot)
            change_field (slop, sizeof slop, _("Other"));
}

/*
 * copy_field - get the next field from the gecos field
 *
 * copy_field copies the next field from the gecos field, returning a
 * pointer to the field which follows, or NULL if there are no more fields.
 *
 *    in - the current GECOS field
 *    out - where to copy the field to
 *    extra - fields with '=' get copied here
 */

static char *copy_field (char *in, char *out, char *extra)
{
      char *cp = NULL;

      while (in) {
            if ((cp = strchr (in, ',')))
                  *cp++ = '\0';

            if (!strchr (in, '='))
                  break;

            if (extra) {
                  if (extra[0])
                        strcat (extra, ",");

                  strcat (extra, in);
            }
            in = cp;
      }
      if (in && out)
            strcpy (out, in);

      return cp;
}


/*
 * chfn - change a user's password file information
 *
 *    This command controls the GECOS field information in the password
 *    file entry.
 *
 *    The valid options are
 *
 *    -f    full name
 *    -r    room number
 *    -w    work phone number
 *    -h    home phone number
 *    -o    other information (*)
 *
 *    (*) requires root permission to execute.
 */

int main (int argc, char **argv)
{
      char *cp;         /* temporary character pointer       */
      const struct passwd *pw;      /* password file entry               */
      struct passwd pwent;    /* modified password file entry      */
      char old_gecos[BUFSIZ]; /* buffer for old GECOS fields       */
      char new_gecos[BUFSIZ]; /* buffer for new GECOS fields       */
      int flag;         /* flag currently being processed    */
      int fflg = 0;           /* -f - set full name                */
      int rflg = 0;           /* -r - set room number              */
      int wflg = 0;           /* -w - set work phone number        */
      int hflg = 0;           /* -h - set home phone number        */
      int oflg = 0;           /* -o - set other information        */
      char *user;

      sanitize_env ();
      setlocale (LC_ALL, "");
      bindtextdomain (PACKAGE, LOCALEDIR);
      textdomain (PACKAGE);

      /*
       * This command behaves different for root and non-root
       * users.
       */

      amroot = (getuid () == 0);
#ifdef      NDBM
      pw_dbm_mode = O_RDWR;
#endif

      /*
       * Get the program name. The program name is used as a
       * prefix to most error messages.
       */

      Prog = Basename (argv[0]);

      OPENLOG ("chfn");

      /* 
       * The remaining arguments will be processed one by one and executed
       * by this command. The name is the last argument if it does not
       * begin with a "-", otherwise the name is determined from the
       * environment and must agree with the real UID. Also, the UID will
       * be checked for any commands which are restricted to root only.
       */

      while ((flag = getopt (argc, argv, "f:r:w:h:o:")) != EOF) {
            switch (flag) {
            case 'f':
                  if (!may_change_field ('f')) {
                        fprintf (stderr,
                               _("%s: Permission denied.\n"),
                               Prog);
                        exit (1);
                  }
                  fflg++;
                  STRFCPY (fullnm, optarg);
                  break;
            case 'r':
                  if (!may_change_field ('r')) {
                        fprintf (stderr,
                               _("%s: Permission denied.\n"),
                               Prog);
                        exit (1);
                  }
                  rflg++;
                  STRFCPY (roomno, optarg);
                  break;
            case 'w':
                  if (!may_change_field ('w')) {
                        fprintf (stderr,
                               _("%s: Permission denied.\n"),
                               Prog);
                        exit (1);
                  }
                  wflg++;
                  STRFCPY (workph, optarg);
                  break;
            case 'h':
                  if (!may_change_field ('h')) {
                        fprintf (stderr,
                               _("%s: Permission denied.\n"),
                               Prog);
                        exit (1);
                  }
                  hflg++;
                  STRFCPY (homeph, optarg);
                  break;
            case 'o':
                  if (!amroot) {
                        fprintf (stderr,
                               _("%s: Permission denied.\n"),
                               Prog);
                        exit (1);
                  }
                  oflg++;
                  STRFCPY (slop, optarg);
                  break;
            default:
                  usage ();
            }
      }

      /*
       * Get the name of the user to check. It is either the command line
       * name, or the name getlogin() returns.
       */

      if (optind < argc) {
            user = argv[optind];
            pw = getpwnam (user);
            if (!pw) {
                  fprintf (stderr, _("%s: Unknown user %s\n"), Prog,
                         user);
                  exit (1);
            }
      } else {
            pw = get_my_pwent ();
            if (!pw) {
                  fprintf (stderr,
                         _
                         ("%s: Cannot determine your user name.\n"),
                         Prog);
                  exit (1);
            }
            user = xstrdup (pw->pw_name);
      }

#ifdef      USE_NIS
      /*
       * Now we make sure this is a LOCAL password entry for this user ...
       */

      if (__ispwNIS ()) {
            char *nis_domain;
            char *nis_master;

            fprintf (stderr,
                   _("%s: cannot change user `%s' on NIS client.\n"),
                   Prog, user);

            if (!yp_get_default_domain (&nis_domain) &&
                !yp_master (nis_domain, "passwd.byname",
                        &nis_master)) {
                  fprintf (stderr,
                         _
                         ("%s: `%s' is the NIS master for this client.\n"),
                         Prog, nis_master);
            }
            exit (1);
      }
#endif

      /*
       * Non-privileged users are only allowed to change the gecos field
       * if the UID of the user matches the current real UID.
       */

      if (!amroot && pw->pw_uid != getuid ()) {
            fprintf (stderr, _("%s: Permission denied.\n"), Prog);
            closelog ();
            exit (1);
      }

      /*
       * Non-privileged users are optionally authenticated (must enter the
       * password of the user whose information is being changed) before
       * any changes can be made. Idea from util-linux chfn/chsh. 
       * --marekm
       */

      if (!amroot && getdef_bool ("CHFN_AUTH"))
            passwd_check (pw->pw_name, pw->pw_passwd, "chfn");

      /*
       * Now get the full name. It is the first comma separated field in
       * the GECOS field.
       */

      STRFCPY (old_gecos, pw->pw_gecos);
      cp = copy_field (old_gecos, fflg ? (char *) 0 : fullnm, slop);

      /*
       * Now get the room number. It is the next comma separated field,
       * if there is indeed one.
       */

      if (cp)
            cp = copy_field (cp, rflg ? (char *) 0 : roomno, slop);

      /*
       * Now get the work phone number. It is the third field.
       */

      if (cp)
            cp = copy_field (cp, wflg ? (char *) 0 : workph, slop);

      /*
       * Now get the home phone number. It is the fourth field.
       */

      if (cp)
            cp = copy_field (cp, hflg ? (char *) 0 : homeph, slop);

      /*
       * Anything left over is "slop".
       */

      if (cp && !oflg) {
            if (slop[0])
                  strcat (slop, ",");

            strcat (slop, cp);
      }

      /*
       * If none of the fields were changed from the command line, let the
       * user interactively change them.
       */

      if (!fflg && !rflg && !wflg && !hflg && !oflg) {
            printf (_("Changing the user information for %s\n"), user);
            new_fields ();
      }

      /*
       * Check all of the fields for valid information
       */

      if (valid_field (fullnm, ":,=")) {
            fprintf (stderr, _("%s: invalid name: \"%s\"\n"), Prog,
                   fullnm);
            closelog ();
            exit (1);
      }
      if (valid_field (roomno, ":,=")) {
            fprintf (stderr, _("%s: invalid room number: \"%s\"\n"),
                   Prog, roomno);
            closelog ();
            exit (1);
      }
      if (valid_field (workph, ":,=")) {
            fprintf (stderr, _("%s: invalid work phone: \"%s\"\n"),
                   Prog, workph);
            closelog ();
            exit (1);
      }
      if (valid_field (homeph, ":,=")) {
            fprintf (stderr, _("%s: invalid home phone: \"%s\"\n"),
                   Prog, homeph);
            closelog ();
            exit (1);
      }
      if (valid_field (slop, ":")) {
            fprintf (stderr,
                   _("%s: \"%s\" contains illegal characters\n"),
                   Prog, slop);
            closelog ();
            exit (1);
      }

      /*
       * Build the new GECOS field by plastering all the pieces together,
       * if they will fit ...
       */

      if (strlen (fullnm) + strlen (roomno) + strlen (workph) +
          strlen (homeph) + strlen (slop) > (unsigned int) 80) {
            fprintf (stderr, _("%s: fields too long\n"), Prog);
            closelog ();
            exit (1);
      }
      snprintf (new_gecos, sizeof new_gecos, "%s,%s,%s,%s%s%s",
              fullnm, roomno, workph, homeph, slop[0] ? "," : "",
              slop);

      /*
       * Before going any further, raise the ulimit to prevent colliding
       * into a lowered ulimit, and set the real UID to root to protect
       * against unexpected signals. Any keyboard signals are set to be
       * ignored.
       */

      if (setuid (0)) {
            fprintf (stderr, _("Cannot change ID to root.\n"));
            SYSLOG ((LOG_ERR, "can't setuid(0)"));
            closelog ();
            exit (1);
      }
      pwd_init ();

      /*
       * The passwd entry is now ready to be committed back to the
       * password file. Get a lock on the file and open it.
       */

      if (!pw_lock ()) {
            fprintf (stderr,
                   _
                   ("Cannot lock the password file; try again later.\n"));
            SYSLOG ((LOG_WARN, "can't lock /etc/passwd"));
            closelog ();
            exit (1);
      }
      if (!pw_open (O_RDWR)) {
            fprintf (stderr, _("Cannot open the password file.\n"));
            pw_unlock ();
            SYSLOG ((LOG_ERR, "can't open /etc/passwd"));
            closelog ();
            exit (1);
      }

      /*
       * Get the entry to update using pw_locate() - we want the real one
       * from /etc/passwd, not the one from getpwnam() which could contain
       * the shadow password if (despite the warnings) someone enables
       * AUTOSHADOW (or SHADOW_COMPAT in libc).  --marekm
       */
      pw = pw_locate (user);
      if (!pw) {
            pw_unlock ();
            fprintf (stderr,
                   _("%s: %s not found in /etc/passwd\n"), Prog,
                   user);
            exit (1);
      }

      /*
       * Make a copy of the entry, then change the gecos field. The other
       * fields remain unchanged.
       */
      pwent = *pw;
      pwent.pw_gecos = new_gecos;

      /*
       * Update the passwd file entry. If there is a DBM file, update that
       * entry as well.
       */

      if (!pw_update (&pwent)) {
            fprintf (stderr,
                   _("Error updating the password entry.\n"));
            pw_unlock ();
            SYSLOG ((LOG_ERR, "error updating passwd entry"));
            closelog ();
            exit (1);
      }
#ifdef NDBM
      if (pw_dbm_present () && !pw_dbm_update (&pwent)) {
            fprintf (stderr,
                   _("Error updating the DBM password entry.\n"));
            pw_unlock ();
            SYSLOG ((LOG_ERR, "error updating DBM passwd entry"));
            closelog ();
            exit (1);
      }
      endpwent ();
#endif

      /*
       * Changes have all been made, so commit them and unlock the file.
       */

      if (!pw_close ()) {
            fprintf (stderr,
                   _("Cannot commit password file changes.\n"));
            pw_unlock ();
            SYSLOG ((LOG_ERR, "can't rewrite /etc/passwd"));
            closelog ();
            exit (1);
      }
      if (!pw_unlock ()) {
            fprintf (stderr, _("Cannot unlock the password file.\n"));
            SYSLOG ((LOG_ERR, "can't unlock /etc/passwd"));
            closelog ();
            exit (1);
      }
      SYSLOG ((LOG_INFO, "changed user `%s' information", user));
      closelog ();
      exit (0);
}

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