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 #include <errno.h>
  48 #include <fcntl.h>
  49 #include <paths.h>
  50 #include <pwd.h>
  51 #include <shadow.h>
  52 #include <signal.h>
  53 #include <stdio.h>
  54 #include <stdlib.h>
  55 #include <string.h>
  56 #include <sys/file.h>
  57 #include <sys/param.h>
  58 #include <sys/resource.h>
  59 #include <sys/stat.h>
  60 #include <sys/time.h>
  61 #include <sys/types.h>
  62 #include <sys/wait.h>
  63 #include <unistd.h>
  64 #include <getopt.h>
  65
  66 #include "c.h"
  67 #include "fileutils.h"
  68 #include "closestream.h"
  69 #include "nls.h"
  70 #include "setpwnam.h"
  71 #include "strutils.h"
  72 #include "xalloc.h"
  73 #include "rpmatch.h"
  74
  75 #ifdef HAVE_LIBSELINUX
  76 # include <selinux/selinux.h>
  77 #endif
  78
  79 #define FILENAMELEN 67
  80
  81 enum {
  82         VIPW,
  83         VIGR
  84 };
  85 static int program;
  86 static char orig_file[FILENAMELEN];     /* original file /etc/passwd or /etc/group */
  87 static char *tmp_file;                  /* tmp file */
  88
  89 void pw_error (char *, int, int);
  90
  91 static void copyfile(int from, int to)
  92 {
  93         int nr, nw, off;
  94         char buf[8 * 1024];
  95
  96         while ((nr = read(from, buf, sizeof(buf))) > 0)
  97                 for (off = 0; off < nr; nr -= nw, off += nw)
  98                         if ((nw = write(to, buf + off, nr)) < 0)
  99                                 pw_error(tmp_file, 1, 1);
 100
 101         if (nr < 0)
 102                 pw_error(orig_file, 1, 1);
 103 #ifdef HAVE_EXPLICIT_BZERO
 104         explicit_bzero(buf, sizeof(buf));
 105 #endif
 106 }
 107
 108 static void pw_init(void)
 109 {
 110         struct rlimit rlim;
 111
 112         /* Unlimited resource limits. */
 113         rlim.rlim_cur = rlim.rlim_max = RLIM_INFINITY;
 114         (void)setrlimit(RLIMIT_CPU, &rlim);
 115         (void)setrlimit(RLIMIT_FSIZE, &rlim);
 116         (void)setrlimit(RLIMIT_STACK, &rlim);
 117         (void)setrlimit(RLIMIT_DATA, &rlim);
 118         (void)setrlimit(RLIMIT_RSS, &rlim);
 119
 120         /* Don't drop core (not really necessary, but GP's). */
 121         rlim.rlim_cur = rlim.rlim_max = 0;
 122         (void)setrlimit(RLIMIT_CORE, &rlim);
 123
 124         /* Turn off signals. */
 125         (void)signal(SIGALRM, SIG_IGN);
 126         (void)signal(SIGHUP, SIG_IGN);
 127         (void)signal(SIGINT, SIG_IGN);
 128         (void)signal(SIGPIPE, SIG_IGN);
 129         (void)signal(SIGQUIT, SIG_IGN);
 130         (void)signal(SIGTERM, SIG_IGN);
 131         (void)signal(SIGTSTP, SIG_IGN);
 132         (void)signal(SIGTTOU, SIG_IGN);
 133
 134         /* Create with exact permissions. */
 135         (void)umask(0);
 136 }
 137
 138 static FILE * pw_tmpfile(int lockfd)
 139 {
 140         FILE *fd;
 141         char *tmpname = NULL;
 142
 143         if ((fd = xfmkstemp(&tmpname, "/etc", ".vipw")) == NULL) {
 144                 ulckpwdf();
 145                 err(EXIT_FAILURE, _("can't open temporary file"));
 146         }
 147
 148         copyfile(lockfd, fileno(fd));
 149         tmp_file = tmpname;
 150         return fd;
 151 }
 152
 153 static void pw_write(void)
 154 {
 155         char tmp[FILENAMELEN + 4];
 156
 157         sprintf(tmp, "%s%s", orig_file, ".OLD");
 158         unlink(tmp);
 159
 160         if (link(orig_file, tmp))
 161                 warn(_("%s: create a link to %s failed"), orig_file, tmp);
 162
 163 #ifdef HAVE_LIBSELINUX
 164         if (is_selinux_enabled() > 0) {
 165                 security_context_t passwd_context = NULL;
 166                 int ret = 0;
 167                 if (getfilecon(orig_file, &passwd_context) < 0) {
 168                         warnx(_("Can't get context for %s"), orig_file);
 169                         pw_error(orig_file, 1, 1);
 170                 }
 171                 ret = setfilecon(tmp_file, passwd_context);
 172                 freecon(passwd_context);
 173                 if (ret != 0) {
 174                         warnx(_("Can't set context for %s"), tmp_file);
 175                         pw_error(tmp_file, 1, 1);
 176                 }
 177         }
 178 #endif
 179
 180         if (rename(tmp_file, orig_file) == -1) {
 181                 int errsv = errno;
 182                 errx(EXIT_FAILURE,
 183                      ("cannot write %s: %s (your changes are still in %s)"),
 184                      orig_file, strerror(errsv), tmp_file);
 185         }
 186         unlink(tmp_file);
 187         free(tmp_file);
 188         tmp_file = NULL;
 189 }
 190
 191 static void pw_edit(void)
 192 {
 193         int pstat;
 194         pid_t pid;
 195         char *p, *editor, *tk;
 196
 197         editor = getenv("EDITOR");
 198         editor = xstrdup(editor ? editor : _PATH_VI);
 199
 200         tk = strtok(editor, " \t");
 201         if (tk && (p = strrchr(tk, '/')) != NULL)
 202                 ++p;
 203         else
 204                 p = editor;
 205
 206         pid = fork();
 207         if (pid < 0)
 208                 err(EXIT_FAILURE, _("fork failed"));
 209
 210         if (!pid) {
 211                 execlp(editor, p, tmp_file, NULL);
 212                 errexec(editor);
 213         }
 214         for (;;) {
 215                 pid = waitpid(pid, &pstat, WUNTRACED);
 216                 if (WIFSTOPPED(pstat)) {
 217                         /* the editor suspended, so suspend us as well */
 218                         kill(getpid(), SIGSTOP);
 219                         kill(pid, SIGCONT);
 220                 } else {
 221                         break;
 222                 }
 223         }
 224         if (pid == -1 || !WIFEXITED(pstat) || WEXITSTATUS(pstat) != 0)
 225                 pw_error(editor, 1, 1);
 226
 227         free(editor);
 228 }
 229
 230 void __attribute__((__noreturn__))
 231 pw_error(char *name, int err, int eval)
 232 {
 233         if (err) {
 234                 if (name)
 235                         warn("%s: ", name);
 236                 else
 237                         warn(NULL);
 238         }
 239         warnx(_("%s unchanged"), orig_file);
 240
 241         if (tmp_file)
 242                 unlink(tmp_file);
 243         ulckpwdf();
 244         exit(eval);
 245 }
 246
 247 static void edit_file(int is_shadow)
 248 {
 249         struct stat begin, end;
 250         int passwd_file, ch_ret;
 251         FILE *tmp_fd;
 252
 253         pw_init();
 254
 255         /* acquire exclusive lock */
 256         if (lckpwdf() < 0)
 257                 err(EXIT_FAILURE, _("cannot get lock"));
 258
 259         passwd_file = open(orig_file, O_RDONLY | O_CLOEXEC, 0);
 260         if (passwd_file < 0)
 261                 err(EXIT_FAILURE, _("cannot open %s"), orig_file);
 262         tmp_fd = pw_tmpfile(passwd_file);
 263
 264         if (fstat(fileno(tmp_fd), &begin))
 265                 pw_error(tmp_file, 1, 1);
 266
 267         pw_edit();
 268
 269         if (fstat(fileno(tmp_fd), &end))
 270                 pw_error(tmp_file, 1, 1);
 271         /* Some editors, such as Vim with 'writebackup' mode enabled,
 272          * use "atomic save" in which the old file is deleted and a new
 273          * one with the same name created in its place.  */
 274         if (end.st_nlink == 0) {
 275                 if (close_stream(tmp_fd) != 0)
 276                         err(EXIT_FAILURE, _("write error"));
 277                 tmp_fd = fopen(tmp_file, "r" UL_CLOEXECSTR);
 278                 if (!tmp_fd)
 279                         err(EXIT_FAILURE, _("cannot open %s"), tmp_file);
 280                 if (fstat(fileno(tmp_fd), &end))
 281                         pw_error(tmp_file, 1, 1);
 282         }
 283         if (begin.st_mtime == end.st_mtime) {
 284                 warnx(_("no changes made"));
 285                 pw_error((char *)NULL, 0, 0);
 286         }
 287         /* pw_tmpfile() will create the file with mode 600 */
 288         if (!is_shadow)
 289                 ch_ret = fchmod(fileno(tmp_fd), 0644);
 290         else
 291                 ch_ret = fchmod(fileno(tmp_fd), 0400);
 292         if (ch_ret < 0)
 293                 err(EXIT_FAILURE, "%s: %s", _("cannot chmod file"), orig_file);
 294         if (close_stream(tmp_fd) != 0)
 295                 err(EXIT_FAILURE, _("write error"));
 296         pw_write();
 297         close(passwd_file);
 298         ulckpwdf();
 299 }
 300
 301 static void __attribute__((__noreturn__)) usage(void)
 302 {
 303         FILE *out = stdout;
 304         fputs(USAGE_HEADER, out);
 305         fprintf(out, " %s\n", program_invocation_short_name);
 306
 307         fputs(USAGE_SEPARATOR, out);
 308         fputs(_("Edit the password or group file.\n"), out);
 309
 310         fputs(USAGE_OPTIONS, out);
 311         printf(USAGE_HELP_OPTIONS(16));
 312         printf(USAGE_MAN_TAIL("vipw(8)"));
 313         exit(EXIT_SUCCESS);
 314 }
 315
 316 int main(int argc, char *argv[])
 317 {
 318         int c;
 319         static const struct option longopts[] = {
 320                 {"version", no_argument, NULL, 'V'},
 321                 {"help", no_argument, NULL, 'h'},
 322                 {NULL, 0, NULL, 0}
 323         };
 324
 325         setlocale(LC_ALL, "");
 326         bindtextdomain(PACKAGE, LOCALEDIR);
 327         textdomain(PACKAGE);
 328         close_stdout_atexit();
 329
 330         if (!strcmp(program_invocation_short_name, "vigr")) {
 331                 program = VIGR;
 332                 xstrncpy(orig_file, GROUP_FILE, sizeof(orig_file));
 333         } else {
 334                 program = VIPW;
 335                 xstrncpy(orig_file, PASSWD_FILE, sizeof(orig_file));
 336         }
 337
 338         while ((c = getopt_long(argc, argv, "Vh", longopts, NULL)) != -1) {
 339                 switch (c) {
 340                 case 'V':
 341                         print_version(EXIT_SUCCESS);
 342                 case 'h':
 343                         usage();
 344                 default:
 345                         errtryhelp(EXIT_FAILURE);
 346                 }
 347         }
 348
 349         edit_file(0);
 350
 351         if (program == VIGR)
 352                 xstrncpy(orig_file, SGROUP_FILE, sizeof(orig_file));
 353         else
 354                 xstrncpy(orig_file, SHADOW_FILE, sizeof(orig_file));
 355
 356         if (access(orig_file, F_OK) == 0) {
 357                 char response[80];
 358
 359                 fputs((program == VIGR)
 360                        ? _("You are using shadow groups on this system.\n")
 361                        : _("You are using shadow passwords on this system.\n"), stdout);
 362
 363                 /* TRANSLATORS: this program uses for y and n rpmatch(3),
 364                  * which means they can be translated. */
 365                 printf(_("Would you like to edit %s now [y/n]? "), orig_file);
 366
 367                 if (fgets(response, sizeof(response), stdin) &&
 368                     rpmatch(response) == RPMATCH_YES)
 369                         edit_file(1);
 370         }
 371         exit(EXIT_SUCCESS);
 372 }