term-utils/wall.c

   1 /*
   2  * Copyright (c) 1988, 1990, 1993
   3  *      The Regents of the University of California.  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  * Modified Sun Mar 12 10:34:34 1995, faith@cs.unc.edu, for Linux
  34  */
  35
  36 /*
  37  * This program is not related to David Wall, whose Stanford Ph.D. thesis
  38  * is entitled "Mechanisms for Broadcast and Selective Broadcast".
  39  *
  40  * 1999-02-22 Arkadiusz Miśkiewicz <misiek@pld.ORG.PL>
  41  * - added Native Language Support
  42  *
  43  */
  44
  45 #include <sys/param.h>
  46 #include <sys/stat.h>
  47 #include <sys/time.h>
  48 #include <sys/uio.h>
  49
  50 #include <errno.h>
  51 #include <paths.h>
  52 #include <ctype.h>
  53 #include <pwd.h>
  54 #include <stdio.h>
  55 #include <stdlib.h>
  56 #include <string.h>
  57 #include <time.h>
  58 #include <unistd.h>
  59 #include <utmpx.h>
  60 #include <getopt.h>
  61 #include <sys/types.h>
  62 #include <grp.h>
  63
  64 #if defined(USE_SYSTEMD) && HAVE_DECL_SD_SESSION_GET_USERNAME == 1
  65 # include <systemd/sd-login.h>
  66 # include <systemd/sd-daemon.h>
  67 #endif
  68
  69 #include "nls.h"
  70 #include "xalloc.h"
  71 #include "strutils.h"
  72 #include "ttymsg.h"
  73 #include "pathnames.h"
  74 #include "carefulputc.h"
  75 #include "c.h"
  76 #include "cctype.h"
  77 #include "fileutils.h"
  78 #include "closestream.h"
  79 #include "timeutils.h"
  80 #include "pwdutils.h"
  81 #include "strv.h"
  82
  83 #define TERM_WIDTH      79
  84 #define WRITE_TIME_OUT  300             /* in seconds */
  85
  86 /* Function prototypes */
  87 static char *makemsg(char *fname, char **mvec, int mvecsz,
  88                     size_t *mbufsize, int print_banner);
  89
  90 static void __attribute__((__noreturn__)) usage(void)
  91 {
  92         FILE *out = stdout;
  93         fputs(USAGE_HEADER, out);
  94         fprintf(out,
  95               _(" %s [options] [<file> | <message>]\n"), program_invocation_short_name);
  96
  97         fputs(USAGE_SEPARATOR, out);
  98         fputs(_("Write a message to all users.\n"), out);
  99
 100         fputs(USAGE_OPTIONS, out);
 101         fputs(_(" -g, --group <group>     only send message to group\n"), out);
 102         fputs(_(" -n, --nobanner          do not print banner, works only for root\n"), out);
 103         fputs(_(" -t, --timeout <timeout> write timeout in seconds\n"), out);
 104         fputs(USAGE_SEPARATOR, out);
 105         fprintf(out, USAGE_HELP_OPTIONS(25));
 106         fprintf(out, USAGE_MAN_TAIL("wall(1)"));
 107
 108         exit(EXIT_SUCCESS);
 109 }
 110
 111 struct group_workspace {
 112         gid_t   requested_group;
 113         int     ngroups;
 114
 115 /* getgrouplist() on OSX takes int* not gid_t* */
 116 #ifdef __APPLE__
 117         int     *groups;
 118 #else
 119         gid_t   *groups;
 120 #endif
 121 };
 122
 123 static gid_t get_group_gid(const char *group)
 124 {
 125         struct group *gr;
 126         gid_t gid;
 127
 128         if ((gr = getgrnam(group)))
 129                 return gr->gr_gid;
 130
 131         gid = strtou32_or_err(group, _("invalid group argument"));
 132         if (!getgrgid(gid))
 133                 errx(EXIT_FAILURE, _("%s: unknown gid"), group);
 134
 135         return gid;
 136 }
 137
 138 static struct group_workspace *init_group_workspace(const char *group)
 139 {
 140         struct group_workspace *buf;
 141         long n;
 142
 143         n = sysconf(_SC_NGROUPS_MAX);
 144         if (n < 0 || n > INT_MAX - 1)
 145                 return NULL;
 146
 147         buf = xmalloc(sizeof(struct group_workspace));
 148         buf->ngroups = n + 1;   /* room for the primary gid */
 149
 150         buf->requested_group = get_group_gid(group);
 151         buf->groups = xcalloc(buf->ngroups, sizeof(*buf->groups));
 152
 153         return buf;
 154 }
 155
 156 static void free_group_workspace(struct group_workspace *buf)
 157 {
 158         if (!buf)
 159                 return;
 160
 161         free(buf->groups);
 162         free(buf);
 163 }
 164
 165 static int is_gr_member(const char *login, const struct group_workspace *buf)
 166 {
 167         struct passwd *pw;
 168         int ngroups = buf->ngroups;
 169         int rc;
 170
 171         pw = getpwnam(login);
 172         if (!pw)
 173                 return 0;
 174
 175         if (buf->requested_group == pw->pw_gid)
 176                 return 1;
 177
 178         rc = getgrouplist(login, pw->pw_gid, buf->groups, &ngroups);
 179         if (rc < 0) {
 180                 /* buffer too small, not sure how this can happen, since
 181                    we used sysconf to get the size... */
 182                 errx(EXIT_FAILURE,
 183                         _("getgrouplist found more groups than sysconf allows"));
 184         }
 185
 186         for (; ngroups >= 0; --ngroups) {
 187                 if (buf->requested_group == (gid_t) buf->groups[ngroups])
 188                         return 1;
 189         }
 190
 191         return 0;
 192 }
 193
 194 static int has_tty(char **ttys, char *name)
 195 {
 196         char **str;
 197
 198         UL_STRV_FOREACH(str, ttys) {
 199                 if (strcmp(*str, name) == 0)
 200                         return 1;
 201         }
 202
 203         return 0;
 204 }
 205
 206 int main(int argc, char **argv)
 207 {
 208         int ch;
 209         struct iovec iov;
 210         struct utmpx *utmpptr;
 211         char line[sizeof(utmpptr->ut_line) + 1];
 212         int print_banner = TRUE;
 213         struct group_workspace *group_buf = NULL;
 214         char *mbuf, *fname = NULL;
 215         size_t mbufsize;
 216         unsigned timeout = WRITE_TIME_OUT;
 217         char **mvec = NULL, **ttys = NULL, **str;
 218         int mvecsz = 0;
 219
 220         static const struct option longopts[] = {
 221                 { "nobanner",   no_argument,            NULL, 'n' },
 222                 { "timeout",    required_argument,      NULL, 't' },
 223                 { "group",      required_argument,      NULL, 'g' },
 224                 { "version",    no_argument,            NULL, 'V' },
 225                 { "help",       no_argument,            NULL, 'h' },
 226                 { NULL, 0, NULL, 0 }
 227         };
 228
 229         setlocale(LC_ALL, "");
 230         bindtextdomain(PACKAGE, LOCALEDIR);
 231         textdomain(PACKAGE);
 232         close_stdout_atexit();
 233
 234         while ((ch = getopt_long(argc, argv, "nt:g:Vh", longopts, NULL)) != -1) {
 235                 switch (ch) {
 236                 case 'n':
 237                         if (geteuid() == 0)
 238                                 print_banner = FALSE;
 239                         else
 240                                 warnx(_("--nobanner is available only for root"));
 241                         break;
 242                 case 't':
 243                         timeout = strtou32_or_err(optarg, _("invalid timeout argument"));
 244                         if (timeout < 1)
 245                                 errx(EXIT_FAILURE, _("invalid timeout argument: %s"), optarg);
 246                         break;
 247                 case 'g':
 248                         group_buf = init_group_workspace(optarg);
 249                         break;
 250
 251                 case 'V':
 252                         print_version(EXIT_SUCCESS);
 253                 case 'h':
 254                         usage();
 255                 default:
 256                         errtryhelp(EXIT_FAILURE);
 257                 }
 258         }
 259         argc -= optind;
 260         argv += optind;
 261
 262         if (argc == 1 && access(argv[0], F_OK) == 0)
 263                 fname = argv[0];
 264         else if (argc >= 1) {
 265                 mvec = argv;
 266                 mvecsz = argc;
 267         }
 268
 269         mbuf = makemsg(fname, mvec, mvecsz, &mbufsize, print_banner);
 270
 271         iov.iov_base = mbuf;
 272         iov.iov_len = mbufsize;
 273
 274 #if defined(USE_SYSTEMD) && HAVE_DECL_SD_SESSION_GET_USERNAME == 1
 275         if (sd_booted() > 0) {
 276                 char **sessions_list;
 277                 int sessions;
 278
 279                 sessions = sd_get_sessions(&sessions_list);
 280                 if (sessions < 0) {
 281                         warnx(_("error getting sessions: %s"), strerror(-sessions));
 282                         goto utmp;
 283                 }
 284
 285                 for (int i = 0; i < sessions; i++) {
 286                         char *name, *tty;
 287                         int r;
 288
 289                         if ((r = sd_session_get_username(sessions_list[i], &name)) < 0) {
 290                                 warnx(_("get user name failed: %s"), strerror (-r));
 291                                 goto utmp;
 292                         }
 293                         if (!(group_buf && !is_gr_member(name, group_buf))
 294                             && sd_session_get_tty(sessions_list[i], &tty) >= 0
 295                             && ul_strv_consume(&ttys, tty) < 0)
 296                                 err(EXIT_FAILURE, _("failed to allocate lines list"));
 297
 298                         free(name);
 299                         free(sessions_list[i]);
 300                 }
 301                 free(sessions_list);
 302         }
 303 utmp:
 304 #endif
 305         {
 306                 while ((utmpptr = getutxent())) {
 307                         if (!utmpptr->ut_user[0])
 308                                 continue;
 309 #ifdef USER_PROCESS
 310                         if (utmpptr->ut_type != USER_PROCESS)
 311                                 continue;
 312 #endif
 313                         /* Joey Hess reports that use-sessreg in /etc/X11/wdm/ produces
 314                          * ut_line entries like :0, and a write to /dev/:0 fails.
 315                          *
 316                          * It also seems that some login manager may produce empty ut_line.
 317                          */
 318                         if (!*utmpptr->ut_line || *utmpptr->ut_line == ':')
 319                                 continue;
 320
 321                         if (group_buf && !is_gr_member(utmpptr->ut_user, group_buf))
 322                                 continue;
 323
 324                         mem2strcpy(line, utmpptr->ut_line, sizeof(utmpptr->ut_line), sizeof(line));
 325                         if (has_tty(ttys, line))
 326                                 continue;
 327                         if (ul_strv_extend(&ttys, line) < 0)
 328                                 err(EXIT_FAILURE, _("failed to allocate lines list"));
 329                 }
 330                 endutxent();
 331         }
 332
 333         UL_STRV_FOREACH(str, ttys) {
 334                 char *er = ttymsg(&iov, 1, *str, timeout);
 335                 if (er)
 336                          warnx("%s", er);
 337         }
 338
 339         ul_strv_free(ttys);
 340         free(mbuf);
 341         free_group_workspace(group_buf);
 342         exit(EXIT_SUCCESS);
 343 }
 344
 345 static char *makemsg(char *fname, char **mvec, int mvecsz,
 346                      size_t *mbufsize, int print_banner)
 347 {
 348         char *lbuf, *retbuf;
 349         FILE * fs = open_memstream(&retbuf, mbufsize);
 350         size_t lbuflen = 512;
 351         lbuf = xmalloc(lbuflen);
 352
 353         if (print_banner == TRUE) {
 354                 char *hostname = xgethostname();
 355                 char *whombuf, *whom, *where, date[CTIME_BUFSIZ];
 356                 time_t now;
 357
 358                 whombuf = whom = xgetlogin();
 359                 if (!whom) {
 360                         whom = "<someone>";
 361                         warn(_("cannot get passwd uid"));
 362                 }
 363                 where = ttyname(STDOUT_FILENO);
 364                 if (!where) {
 365                         where = "somewhere";
 366                 } else if (strncmp(where, "/dev/", 5) == 0)
 367                         where += 5;
 368
 369                 time(&now);
 370                 ctime_r(&now, date);
 371                 date[strlen(date) - 1] = '\0';
 372
 373                 /*
 374                  * all this stuff is to blank out a square for the message;
 375                  * we wrap message lines at column 79, not 80, because some
 376                  * terminals wrap after 79, some do not, and we can't tell.
 377                  * Which means that we may leave a non-blank character
 378                  * in column 80, but that can't be helped.
 379                  */
 380                 /* snprintf is not always available, but the sprintf's here
 381                    will not overflow as long as %d takes at most 100 chars */
 382                 fprintf(fs, "\r%*s\r\n", TERM_WIDTH, " ");
 383
 384                 snprintf(lbuf, lbuflen,
 385                                 _("Broadcast message from %s@%s (%s) (%s):"),
 386                                 whom, hostname, where, date);
 387                 fprintf(fs, "%-*.*s\007\007\r\n", TERM_WIDTH, TERM_WIDTH, lbuf);
 388                 free(hostname);
 389                 free(whombuf);
 390         }
 391         fprintf(fs, "%*s\r\n", TERM_WIDTH, " ");
 392
 393          if (mvec) {
 394                 /*
 395                  * Read message from argv[]
 396                  */
 397                 int i;
 398
 399                 for (i = 0; i < mvecsz; i++) {
 400                         fputs_careful(mvec[i], fs, '^', true, TERM_WIDTH);
 401                         if (i < mvecsz - 1)
 402                                 fputc(' ', fs);
 403                 }
 404                 fputs("\r\n", fs);
 405         } else {
 406                 /*
 407                  * read message from <file>
 408                  */
 409                 if (fname) {
 410                         /*
 411                          * When we are not root, but suid or sgid, refuse to read files
 412                          * (e.g. device files) that the user may not have access to.
 413                          * After all, our invoker can easily do "wall < file"
 414                          * instead of "wall file".
 415                          */
 416                         if (getuid() && is_privileged_execution())
 417                                 errx(EXIT_FAILURE, _("will not read %s - use stdin."),
 418                                      fname);
 419
 420                         if (!freopen(fname, "r", stdin))
 421                                 err(EXIT_FAILURE, _("cannot open %s"), fname);
 422
 423                 }
 424
 425                 /*
 426                  * Read message from stdin.
 427                  */
 428                 while (getline(&lbuf, &lbuflen, stdin) >= 0)
 429                         fputs_careful(lbuf, fs, '^', true, TERM_WIDTH);
 430         }
 431         fprintf(fs, "%*s\r\n", TERM_WIDTH, " ");
 432
 433         free(lbuf);
 434
 435         fclose(fs);
 436         return retbuf;
 437 }