libexec/rexecd/rexecd.c

   1 /*
   2  * Copyright (c) 1983, 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  * @(#) Copyright (c) 1983, 1993 The Regents of the University of California.  All rights reserved.
  34  * @(#)rexecd.c 8.1 (Berkeley) 6/4/93
  35  * $FreeBSD: src/libexec/rexecd/rexecd.c,v 1.18.2.3 2002/05/14 22:27:21 des Exp $
  36  * $DragonFly: src/libexec/rexecd/rexecd.c,v 1.5 2007/11/25 01:28:23 swildner Exp $
  37  */
  38
  39 #include <sys/param.h>
  40 #include <sys/ioctl.h>
  41 #include <sys/socket.h>
  42
  43 #include <netinet/in.h>
  44
  45 #include <err.h>
  46 #ifdef DEBUG
  47 #include <fcntl.h>
  48 #endif
  49 #include <libutil.h>
  50 #include <paths.h>
  51 #include <signal.h>
  52 #include <stdio.h>
  53 #include <stdlib.h>
  54 #include <skey.h>
  55 #include <string.h>
  56 #include <syslog.h>
  57 #include <unistd.h>
  58
  59 char    username[MAXLOGNAME + 5 + 1] = "USER=";
  60 char    homedir[MAXPATHLEN + 5 + 1] = "HOME=";
  61 char    shell[MAXPATHLEN + 6 + 1] = "SHELL=";
  62 char    path[sizeof(_PATH_DEFPATH) + sizeof("PATH=")] = "PATH=";
  63 char    *envinit[] =
  64             {homedir, shell, path, username, 0};
  65 char    **environ;
  66 char    remote[MAXHOSTNAMELEN];
  67
  68 struct  sockaddr_in asin = { AF_INET };
  69
  70 void doit (int, struct sockaddr_in *);
  71 void getstr (char *, int, char *);
  72 /*VARARGS1*/
  73 void error ();
  74
  75 int no_uid_0 = 1;
  76
  77 void
  78 usage(void)
  79 {
  80         syslog(LOG_ERR, "usage: rexecd [-i]");
  81         exit(1);
  82 }
  83
  84 /*
  85  * remote execute server:
  86  *      username\0
  87  *      password\0
  88  *      command\0
  89  *      data
  90  */
  91 /*ARGSUSED*/
  92 int
  93 main(argc, argv)
  94         int argc;
  95         char **argv;
  96 {
  97         struct sockaddr_in from;
  98         int fromlen;
  99         int ch;
 100
 101         openlog("rexecd", LOG_PID, LOG_AUTH);
 102
 103         while ((ch = getopt(argc, argv, "i")) != -1)
 104           switch (ch) {
 105           case 'i':
 106                 no_uid_0 = 0;
 107                 break;
 108           default:
 109                 usage();
 110           }
 111         argc -= optind;
 112         argv += optind;
 113
 114         fromlen = sizeof (from);
 115         if (getpeername(0, (struct sockaddr *)&from, &fromlen) < 0)
 116                 err(1, "getpeername");
 117
 118         realhostname(remote, sizeof(remote) - 1, &from.sin_addr);
 119
 120         doit(0, &from);
 121         return(0);
 122 }
 123
 124 void
 125 doit(f, fromp)
 126         int f;
 127         struct sockaddr_in *fromp;
 128 {
 129         FILE *fp;
 130         char cmdbuf[NCARGS+1], *cp, *namep;
 131 #ifdef SKEY
 132         char user[16], pass[100];
 133 #else /* SKEY */
 134         char user[16], pass[16];
 135 #endif /* SKEY */
 136         struct passwd *pwd;
 137         int s;
 138         u_short port;
 139         int pv[2], pid, ready, readfrom, cc;
 140         char buf[BUFSIZ], sig;
 141         int one = 1;
 142
 143         (void) signal(SIGINT, SIG_DFL);
 144         (void) signal(SIGQUIT, SIG_DFL);
 145         (void) signal(SIGTERM, SIG_DFL);
 146 #ifdef DEBUG
 147         { int t = open(_PATH_TTY, 2);
 148           if (t >= 0) {
 149                 ioctl(t, TIOCNOTTY, (char *)0);
 150                 (void) close(t);
 151           }
 152         }
 153 #endif
 154         dup2(f, 0);
 155         dup2(f, 1);
 156         dup2(f, 2);
 157         (void) alarm(60);
 158         port = 0;
 159         for (;;) {
 160                 char c;
 161                 if (read(f, &c, 1) != 1)
 162                         exit(1);
 163                 if (c == 0)
 164                         break;
 165                 port = port * 10 + c - '0';
 166         }
 167         (void) alarm(0);
 168         if (port != 0) {
 169                 s = socket(AF_INET, SOCK_STREAM, 0);
 170                 if (s < 0)
 171                         exit(1);
 172                 if (bind(s, (struct sockaddr *)&asin, sizeof (asin)) < 0)
 173                         exit(1);
 174                 (void) alarm(60);
 175                 fromp->sin_port = htons(port);
 176                 if (connect(s, (struct sockaddr *)fromp, sizeof (*fromp)) < 0)
 177                         exit(1);
 178                 (void) alarm(0);
 179         }
 180         (void) alarm(60);
 181         getstr(user, sizeof(user), "username");
 182         getstr(pass, sizeof(pass), "password");
 183         getstr(cmdbuf, sizeof(cmdbuf), "command");
 184         (void) alarm(0);
 185         setpwent();
 186         pwd = getpwnam(user);
 187         if (pwd == NULL) {
 188                 error("Login incorrect.\n");
 189                 exit(1);
 190         }
 191         endpwent();
 192         if (*pwd->pw_passwd != '\0') {
 193 #ifdef SKEY
 194                 namep = skey_crypt(pass, pwd->pw_passwd, pwd,
 195                                    skeyaccess(user, NULL, remote, NULL));
 196 #else /* SKEY */
 197                 namep = crypt(pass, pwd->pw_passwd);
 198 #endif /* SKEY */
 199                 if (strcmp(namep, pwd->pw_passwd)) {
 200                         syslog(LOG_ERR, "LOGIN FAILURE from %s, %s",
 201                                remote, user);
 202                         error("Login incorrect.\n");
 203                         exit(1);
 204                 }
 205         }
 206
 207         if ((pwd->pw_uid == 0 && no_uid_0) || *pwd->pw_passwd == '\0' ||
 208             (pwd->pw_expire && time(NULL) >= pwd->pw_expire)) {
 209                 syslog(LOG_ERR, "%s LOGIN REFUSED from %s", user, remote);
 210                 error("Login incorrect.\n");
 211                 exit(1);
 212         }
 213
 214         if ((fp = fopen(_PATH_FTPUSERS, "r")) != NULL) {
 215                 while (fgets(buf, sizeof(buf), fp) != NULL) {
 216                         if ((cp = index(buf, '\n')) != NULL)
 217                                 *cp = '\0';
 218                         if (strcmp(buf, pwd->pw_name) == 0) {
 219                                 syslog(LOG_ERR, "%s LOGIN REFUSED from %s",
 220                                        user, remote);
 221                                 error("Login incorrect.\n");
 222                                 exit(1);
 223                         }
 224                 }
 225         }
 226         (void) fclose(fp);
 227
 228         syslog(LOG_INFO, "login from %s as %s", remote, user);
 229
 230         (void) write(2, "\0", 1);
 231         if (port) {
 232                 (void) pipe(pv);
 233                 pid = fork();
 234                 if (pid == -1)  {
 235                         error("Try again.\n");
 236                         exit(1);
 237                 }
 238                 if (pid) {
 239                         (void) close(0); (void) close(1); (void) close(2);
 240                         (void) close(f); (void) close(pv[1]);
 241                         readfrom = (1<<s) | (1<<pv[0]);
 242                         ioctl(pv[1], FIONBIO, (char *)&one);
 243                         /* should set s nbio! */
 244                         do {
 245                                 ready = readfrom;
 246                                 (void) select(16, (fd_set *)&ready,
 247                                     (fd_set *)NULL, (fd_set *)NULL,
 248                                     (struct timeval *)NULL);
 249                                 if (ready & (1<<s)) {
 250                                         if (read(s, &sig, 1) <= 0)
 251                                                 readfrom &= ~(1<<s);
 252                                         else
 253                                                 killpg(pid, sig);
 254                                 }
 255                                 if (ready & (1<<pv[0])) {
 256                                         cc = read(pv[0], buf, sizeof (buf));
 257                                         if (cc <= 0) {
 258                                                 shutdown(s, SHUT_RDWR);
 259                                                 readfrom &= ~(1<<pv[0]);
 260                                         } else
 261                                                 (void) write(s, buf, cc);
 262                                 }
 263                         } while (readfrom);
 264                         exit(0);
 265                 }
 266                 setpgrp(0, getpid());
 267                 (void) close(s); (void)close(pv[0]);
 268                 dup2(pv[1], 2);
 269         }
 270         if (*pwd->pw_shell == '\0')
 271                 pwd->pw_shell = _PATH_BSHELL;
 272         if (f > 2)
 273                 (void) close(f);
 274         if (setlogin(pwd->pw_name) < 0)
 275                 syslog(LOG_ERR, "setlogin() failed: %m");
 276         (void) setgid((gid_t)pwd->pw_gid);
 277         initgroups(pwd->pw_name, pwd->pw_gid);
 278         (void) setuid((uid_t)pwd->pw_uid);
 279         (void)strcat(path, _PATH_DEFPATH);
 280         environ = envinit;
 281         strncat(homedir, pwd->pw_dir, sizeof(homedir)-6);
 282         strncat(shell, pwd->pw_shell, sizeof(shell)-7);
 283         strncat(username, pwd->pw_name, sizeof(username)-6);
 284         cp = strrchr(pwd->pw_shell, '/');
 285         if (cp)
 286                 cp++;
 287         else
 288                 cp = pwd->pw_shell;
 289         if (chdir(pwd->pw_dir) < 0) {
 290                 error("No remote directory.\n");
 291                 exit(1);
 292         }
 293         execl(pwd->pw_shell, cp, "-c", cmdbuf, 0);
 294         err(1, "%s", pwd->pw_shell);
 295 }
 296
 297 /*VARARGS1*/
 298 void
 299 error(fmt, a1, a2, a3)
 300         char *fmt;
 301         int a1, a2, a3;
 302 {
 303         char buf[BUFSIZ];
 304
 305         buf[0] = 1;
 306         (void) snprintf(buf+1, sizeof(buf) - 1, fmt, a1, a2, a3);
 307         (void) write(2, buf, strlen(buf));
 308 }
 309
 310 void
 311 getstr(buf, cnt, err)
 312         char *buf;
 313         int cnt;
 314         char *err;
 315 {
 316         char c;
 317
 318         do {
 319                 if (read(0, &c, 1) != 1)
 320                         exit(1);
 321                 *buf++ = c;
 322                 if (--cnt == 0) {
 323                         error("%s too long\n", err);
 324                         exit(1);
 325                 }
 326         } while (c != 0);
 327 }