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