login-utils/vipw.c

   1 /*
   2  * Copyright (c) 1987 Regents of the University of California.
   3  * All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions
   7  * are met:
   8  * 1. Redistributions of source code must retain the above copyright
   9  *    notice, this list of conditions and the following disclaimer.
  10  * 2. Redistributions in binary form must reproduce the above copyright
  11  *    notice, this list of conditions and the following disclaimer in the
  12  *    documentation and/or other materials provided with the distribution.
  13  * 3. All advertising materials mentioning features or use of this software
  14  *    must display the following acknowledgement:
  15  *      This product includes software developed by the University of
  16  *      California, Berkeley and its contributors.
  17  * 4. Neither the name of the University 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 REGENTS 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 REGENTS 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  * Updated Thu Oct 12 09:56:55 1995 by faith@cs.unc.edu with security
  34  * patches from Zefram <A.Main@dcs.warwick.ac.uk>
  35  *
  36  * Updated Thu Nov  9 21:58:53 1995 by Martin Schulze
  37  * <joey@finlandia.infodrom.north.de>.  Support for vigr.
  38  *
  39  * Martin Schulze's patches adapted to Util-Linux by Nicolai Langfeldt.
  40  *
  41  * 1999-02-22 Arkadiusz Miśkiewicz <misiek@pld.ORG.PL>
  42  * - added Native Language Support
  43  * Sun Mar 21 1999 - Arnaldo Carvalho de Melo <acme@conectiva.com.br>
  44  * - fixed strerr(errno) in gettext calls
  45  */
  46
  47 /*
  48  * This command is deprecated.  The utility is in maintenance mode,
  49  * meaning we keep them in source tree for backward compatibility
  50  * only.  Do not waste time making this command better, unless the
  51  * fix is about security or other very critical issue.
  52  *
  53  * See Documentation/deprecated.txt for more information.
  54  */
  55
  56 #include <errno.h>
  57 #include <fcntl.h>
  58 #include <paths.h>
  59 #include <pwd.h>
  60 #include <shadow.h>
  61 #include <signal.h>
  62 #include <stdio.h>
  63 #include <stdlib.h>
  64 #include <string.h>
  65 #include <sys/file.h>
  66 #include <sys/param.h>
  67 #include <sys/resource.h>
  68 #include <sys/stat.h>
  69 #include <sys/time.h>
  70 #include <sys/types.h>
  71 #include <sys/wait.h>
  72 #include <unistd.h>
  73
  74 #include "c.h"
  75 #include "fileutils.h"
  76 #include "closestream.h"
  77 #include "nls.h"
  78 #include "setpwnam.h"
  79 #include "strutils.h"
  80 #include "xalloc.h"
  81
  82 #ifdef HAVE_LIBSELINUX
  83 # include <selinux/selinux.h>
  84 #endif
  85
  86 #define FILENAMELEN 67
  87
  88 enum {
  89         VIPW,
  90         VIGR
  91 };
  92 int program;
  93 char orig_file[FILENAMELEN];    /* original file /etc/passwd or /etc/group */
  94 char *tmp_file;                 /* tmp file */
  95
  96 void pw_error __P((char *, int, int));
  97
  98 static void copyfile(int from, int to)
  99 {
 100         int nr, nw, off;
 101         char buf[8 * 1024];
 102
 103         while ((nr = read(from, buf, sizeof(buf))) > 0)
 104                 for (off = 0; off < nr; nr -= nw, off += nw)
 105                         if ((nw = write(to, buf + off, nr)) < 0)
 106                                 pw_error(tmp_file, 1, 1);
 107
 108         if (nr < 0)
 109                 pw_error(orig_file, 1, 1);
 110 }
 111
 112 static void pw_init(void)
 113 {
 114         struct rlimit rlim;
 115
 116         /* Unlimited resource limits. */
 117         rlim.rlim_cur = rlim.rlim_max = RLIM_INFINITY;
 118         (void)setrlimit(RLIMIT_CPU, &rlim);
 119         (void)setrlimit(RLIMIT_FSIZE, &rlim);
 120         (void)setrlimit(RLIMIT_STACK, &rlim);
 121         (void)setrlimit(RLIMIT_DATA, &rlim);
 122         (void)setrlimit(RLIMIT_RSS, &rlim);
 123
 124         /* Don't drop core (not really necessary, but GP's). */
 125         rlim.rlim_cur = rlim.rlim_max = 0;
 126         (void)setrlimit(RLIMIT_CORE, &rlim);
 127
 128         /* Turn off signals. */
 129         (void)signal(SIGALRM, SIG_IGN);
 130         (void)signal(SIGHUP, SIG_IGN);
 131         (void)signal(SIGINT, SIG_IGN);
 132         (void)signal(SIGPIPE, SIG_IGN);
 133         (void)signal(SIGQUIT, SIG_IGN);
 134         (void)signal(SIGTERM, SIG_IGN);
 135         (void)signal(SIGTSTP, SIG_IGN);
 136         (void)signal(SIGTTOU, SIG_IGN);
 137
 138         /* Create with exact permissions. */
 139         (void)umask(0);
 140 }
 141
 142 static FILE * pw_tmpfile(int lockfd)
 143 {
 144         FILE *fd;
 145         char *tmpname = NULL;
 146         char *dir = "/etc";
 147
 148         if ((fd = xfmkstemp(&tmpname, dir)) == NULL) {
 149                 ulckpwdf();
 150                 err(EXIT_FAILURE, _("can't open temporary file"));
 151         }
 152
 153         copyfile(lockfd, fileno(fd));
 154         tmp_file = tmpname;
 155         return fd;
 156 }
 157
 158 static void pw_write(void)
 159 {
 160         char tmp[FILENAMELEN + 4];
 161
 162         sprintf(tmp, "%s%s", orig_file, ".OLD");
 163         unlink(tmp);
 164
 165         if (link(orig_file, tmp))
 166                 warn(_("%s: create a link to %s failed"), orig_file, tmp);
 167
 168 #ifdef HAVE_LIBSELINUX
 169         if (is_selinux_enabled() > 0) {
 170                 security_context_t passwd_context = NULL;
 171                 int ret = 0;
 172                 if (getfilecon(orig_file, &passwd_context) < 0) {
 173                         warnx(_("Can't get context for %s"), orig_file);
 174                         pw_error(orig_file, 1, 1);
 175                 }
 176                 ret = setfilecon(tmp_file, passwd_context);
 177                 freecon(passwd_context);
 178                 if (ret != 0) {
 179                         warnx(_("Can't set context for %s"), tmp_file);
 180                         pw_error(tmp_file, 1, 1);
 181                 }
 182         }
 183 #endif
 184
 185         if (rename(tmp_file, orig_file) == -1) {
 186                 int errsv = errno;
 187                 errx(EXIT_FAILURE,
 188                      ("cannot write %s: %s (your changes are still in %s)"),
 189                      orig_file, strerror(errsv), tmp_file);
 190         }
 191         unlink(tmp_file);
 192         free(tmp_file);
 193 }
 194
 195 static void pw_edit(void)
 196 {
 197         int pstat;
 198         pid_t pid;
 199         char *p, *editor, *tk;
 200
 201         editor = getenv("EDITOR");
 202         editor = xstrdup(editor ? editor : _PATH_VI);
 203
 204         tk = strtok(editor, " \t");
 205         if (tk && (p = strrchr(tk, '/')) != NULL)
 206                 ++p;
 207         else
 208                 p = editor;
 209
 210         pid = fork();
 211         if (pid < 0)
 212                 err(EXIT_FAILURE, _("fork failed"));
 213
 214         if (!pid) {
 215                 execlp(editor, p, tmp_file, NULL);
 216                 /* Shouldn't get here */
 217                 _exit(EXIT_FAILURE);
 218         }
 219         for (;;) {
 220                 pid = waitpid(pid, &pstat, WUNTRACED);
 221                 if (WIFSTOPPED(pstat)) {
 222                         /* the editor suspended, so suspend us as well */
 223                         kill(getpid(), SIGSTOP);
 224                         kill(pid, SIGCONT);
 225                 } else {
 226                         break;
 227                 }
 228         }
 229         if (pid == -1 || !WIFEXITED(pstat) || WEXITSTATUS(pstat) != 0)
 230                 pw_error(editor, 1, 1);
 231
 232         free(editor);
 233 }
 234
 235 void __attribute__((__noreturn__))
 236 pw_error(char *name, int err, int eval)
 237 {
 238         if (err) {
 239                 if (name)
 240                         warn("%s: ", name);
 241                 else
 242                         warn(NULL);
 243         }
 244         warnx(_("%s unchanged"), orig_file);
 245         unlink(tmp_file);
 246         ulckpwdf();
 247         exit(eval);
 248 }
 249
 250 static void edit_file(int is_shadow)
 251 {
 252         struct stat begin, end;
 253         int passwd_file, ch_ret;
 254         FILE *tmp_fd;
 255
 256         pw_init();
 257
 258         /* acquire exclusive lock */
 259         if (lckpwdf() < 0)
 260                 err(EXIT_FAILURE, _("cannot get lock"));
 261
 262         passwd_file = open(orig_file, O_RDONLY, 0);
 263         if (passwd_file < 0)
 264                 err(EXIT_FAILURE, _("cannot open %s"), orig_file);
 265         tmp_fd = pw_tmpfile(passwd_file);
 266
 267         if (fstat(fileno(tmp_fd), &begin))
 268                 pw_error(tmp_file, 1, 1);
 269
 270         pw_edit();
 271
 272         if (fstat(fileno(tmp_fd), &end))
 273                 pw_error(tmp_file, 1, 1);
 274         /* Some editors, such as Vim with 'writebackup' mode enabled,
 275          * use "atomic save" in which the old file is deleted and a new
 276          * one with the same name created in its place.  */
 277         if (end.st_nlink == 0) {
 278                 if (close_stream(tmp_fd) != 0)
 279                         err(EXIT_FAILURE, _("write error"));
 280                 tmp_fd = fopen(tmp_file, "r");
 281                 if (!tmp_file)
 282                         err(EXIT_FAILURE, _("cannot open %s"), tmp_file);
 283                 if (fstat(fileno(tmp_fd), &end))
 284                         pw_error(tmp_file, 1, 1);
 285         }
 286         if (begin.st_mtime == end.st_mtime) {
 287                 warnx(_("no changes made"));
 288                 pw_error((char *)NULL, 0, 0);
 289         }
 290         /* pw_tmpfile() will create the file with mode 600 */
 291         if (!is_shadow)
 292                 ch_ret = fchmod(fileno(tmp_fd), 0644);
 293         else
 294                 ch_ret = fchmod(fileno(tmp_fd), 0400);
 295         if (ch_ret < 0)
 296                 err(EXIT_FAILURE, "%s: %s", _("cannot chmod file"), orig_file);
 297         if (close_stream(tmp_fd) != 0)
 298                 err(EXIT_FAILURE, _("write error"));
 299         pw_write();
 300         close(passwd_file);
 301         ulckpwdf();
 302 }
 303
 304 int main(int argc, char *argv[])
 305 {
 306         setlocale(LC_ALL, "");
 307         bindtextdomain(PACKAGE, LOCALEDIR);
 308         textdomain(PACKAGE);
 309         atexit(close_stdout);
 310
 311         if (!strcmp(program_invocation_short_name, "vigr")) {
 312                 program = VIGR;
 313                 xstrncpy(orig_file, GROUP_FILE, sizeof(orig_file));
 314         } else {
 315                 program = VIPW;
 316                 xstrncpy(orig_file, PASSWD_FILE, sizeof(orig_file));
 317         }
 318
 319         if ((argc > 1) &&
 320             (!strcmp(argv[1], "-V") || !strcmp(argv[1], "--version"))) {
 321                 printf(UTIL_LINUX_VERSION);
 322                 exit(EXIT_SUCCESS);
 323         }
 324
 325         edit_file(0);
 326
 327         if (program == VIGR) {
 328                 strncpy(orig_file, SGROUP_FILE, FILENAMELEN - 1);
 329         } else {
 330                 strncpy(orig_file, SHADOW_FILE, FILENAMELEN - 1);
 331         }
 332
 333         if (access(orig_file, F_OK) == 0) {
 334                 char response[80];
 335
 336                 printf((program == VIGR)
 337                        ? _("You are using shadow groups on this system.\n")
 338                        : _("You are using shadow passwords on this system.\n"));
 339                 /* TRANSLATORS: this program uses for y and n rpmatch(3),
 340                  * which means they can be translated. */
 341                 printf(_("Would you like to edit %s now [y/n]? "), orig_file);
 342
 343                 if (fgets(response, sizeof(response), stdin)) {
 344                         if (rpmatch(response) == 1)
 345                                 edit_file(1);
 346                 }
 347         }
 348         exit(EXIT_SUCCESS);
 349 }