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 1.4 2007/05/18 17:05:12 dillon 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 <skey.h>
  54 #include <string.h>
  55 #include <syslog.h>
  56 #include <unistd.h>
  57
  58 char    username[MAXLOGNAME + 5 + 1] = "USER=";
  59 char    homedir[MAXPATHLEN + 5 + 1] = "HOME=";
  60 char    shell[MAXPATHLEN + 6 + 1] = "SHELL=";
  61 char    path[sizeof(_PATH_DEFPATH) + sizeof("PATH=")] = "PATH=";
  62 char    *envinit[] =
  63             {homedir, shell, path, username, 0};
  64 char    **environ;
  65 char    remote[MAXHOSTNAMELEN];
  66
  67 struct  sockaddr_in asin = { AF_INET };
  68
  69 void doit (int, struct sockaddr_in *);
  70 void getstr (char *, int, char *);
  71 /*VARARGS1*/
  72 void error ();
  73
  74 int no_uid_0 = 1;
  75
  76 void
  77 usage(void)
  78 {
  79         syslog(LOG_ERR, "usage: rexecd [-i]");
  80         exit(1);
  81 }
  82
  83 /*
  84  * remote execute server:
  85  *      username\0
  86  *      password\0
  87  *      command\0
  88  *      data
  89  */
  90 /*ARGSUSED*/
  91 int
  92 main(argc, argv)
  93         int argc;
  94         char **argv;
  95 {
  96         struct sockaddr_in from;
  97         int fromlen;
  98         int ch;
  99
 100         openlog("rexecd", LOG_PID, LOG_AUTH);
 101
 102         while ((ch = getopt(argc, argv, "i")) != -1)
 103           switch (ch) {
 104           case 'i':
 105                 no_uid_0 = 0;
 106                 break;
 107           default:
 108                 usage();
 109           }
 110         argc -= optind;
 111         argv += optind;
 112
 113         fromlen = sizeof (from);
 114         if (getpeername(0, (struct sockaddr *)&from, &fromlen) < 0)
 115                 err(1, "getpeername");
 116
 117         realhostname(remote, sizeof(remote) - 1, &from.sin_addr);
 118
 119         doit(0, &from);
 120         return(0);
 121 }
 122
 123 void
 124 doit(f, fromp)
 125         int f;
 126         struct sockaddr_in *fromp;
 127 {
 128         FILE *fp;
 129         char cmdbuf[NCARGS+1], *cp, *namep;
 130 #ifdef SKEY
 131         char user[16], pass[100];
 132 #else /* SKEY */
 133         char user[16], pass[16];
 134 #endif /* SKEY */
 135         struct passwd *pwd;
 136         int s;
 137         u_short port;
 138         int pv[2], pid, ready, readfrom, cc;
 139         char buf[BUFSIZ], sig;
 140         int one = 1;
 141
 142         (void) signal(SIGINT, SIG_DFL);
 143         (void) signal(SIGQUIT, SIG_DFL);
 144         (void) signal(SIGTERM, SIG_DFL);
 145 #ifdef DEBUG
 146         { int t = open(_PATH_TTY, 2);
 147           if (t >= 0) {
 148                 ioctl(t, TIOCNOTTY, (char *)0);
 149                 (void) close(t);
 150           }
 151         }
 152 #endif
 153         dup2(f, 0);
 154         dup2(f, 1);
 155         dup2(f, 2);
 156         (void) alarm(60);
 157         port = 0;
 158         for (;;) {
 159                 char c;
 160                 if (read(f, &c, 1) != 1)
 161                         exit(1);
 162                 if (c == 0)
 163                         break;
 164                 port = port * 10 + c - '0';
 165         }
 166         (void) alarm(0);
 167         if (port != 0) {
 168                 s = socket(AF_INET, SOCK_STREAM, 0);
 169                 if (s < 0)
 170                         exit(1);
 171                 if (bind(s, (struct sockaddr *)&asin, sizeof (asin)) < 0)
 172                         exit(1);
 173                 (void) alarm(60);
 174                 fromp->sin_port = htons(port);
 175                 if (connect(s, (struct sockaddr *)fromp, sizeof (*fromp)) < 0)
 176                         exit(1);
 177                 (void) alarm(0);
 178         }
 179         (void) alarm(60);
 180         getstr(user, sizeof(user), "username");
 181         getstr(pass, sizeof(pass), "password");
 182         getstr(cmdbuf, sizeof(cmdbuf), "command");
 183         (void) alarm(0);
 184         setpwent();
 185         pwd = getpwnam(user);
 186         if (pwd == NULL) {
 187                 error("Login incorrect.\n");
 188                 exit(1);
 189         }
 190         endpwent();
 191         if (*pwd->pw_passwd != '\0') {
 192 #ifdef SKEY
 193                 namep = skey_crypt(pass, pwd->pw_passwd, pwd,
 194                                    skeyaccess(user, NULL, remote, NULL));
 195 #else /* SKEY */
 196                 namep = crypt(pass, pwd->pw_passwd);
 197 #endif /* SKEY */
 198                 if (strcmp(namep, pwd->pw_passwd)) {
 199                         syslog(LOG_ERR, "LOGIN FAILURE from %s, %s",
 200                                remote, user);
 201                         error("Login incorrect.\n");
 202                         exit(1);
 203                 }
 204         }
 205
 206         if ((pwd->pw_uid == 0 && no_uid_0) || *pwd->pw_passwd == '\0' ||
 207             (pwd->pw_expire && time(NULL) >= pwd->pw_expire)) {
 208                 syslog(LOG_ERR, "%s LOGIN REFUSED from %s", user, remote);
 209                 error("Login incorrect.\n");
 210                 exit(1);
 211         }
 212
 213         if ((fp = fopen(_PATH_FTPUSERS, "r")) != NULL) {
 214                 while (fgets(buf, sizeof(buf), fp) != NULL) {
 215                         if ((cp = index(buf, '\n')) != NULL)
 216                                 *cp = '\0';
 217                         if (strcmp(buf, pwd->pw_name) == 0) {
 218                                 syslog(LOG_ERR, "%s LOGIN REFUSED from %s",
 219                                        user, remote);
 220                                 error("Login incorrect.\n");
 221                                 exit(1);
 222                         }
 223                 }
 224         }
 225         (void) fclose(fp);
 226
 227         syslog(LOG_INFO, "login from %s as %s", remote, user);
 228
 229         (void) write(2, "\0", 1);
 230         if (port) {
 231                 (void) pipe(pv);
 232                 pid = fork();
 233                 if (pid == -1)  {
 234                         error("Try again.\n");
 235                         exit(1);
 236                 }
 237                 if (pid) {
 238                         (void) close(0); (void) close(1); (void) close(2);
 239                         (void) close(f); (void) close(pv[1]);
 240                         readfrom = (1<<s) | (1<<pv[0]);
 241                         ioctl(pv[1], FIONBIO, (char *)&one);
 242                         /* should set s nbio! */
 243                         do {
 244                                 ready = readfrom;
 245                                 (void) select(16, (fd_set *)&ready,
 246                                     (fd_set *)NULL, (fd_set *)NULL,
 247                                     (struct timeval *)NULL);
 248                                 if (ready & (1<<s)) {
 249                                         if (read(s, &sig, 1) <= 0)
 250                                                 readfrom &= ~(1<<s);
 251                                         else
 252                                                 killpg(pid, sig);
 253                                 }
 254                                 if (ready & (1<<pv[0])) {
 255                                         cc = read(pv[0], buf, sizeof (buf));
 256                                         if (cc <= 0) {
 257                                                 shutdown(s, SHUT_RDWR);
 258                                                 readfrom &= ~(1<<pv[0]);
 259                                         } else
 260                                                 (void) write(s, buf, cc);
 261                                 }
 262                         } while (readfrom);
 263                         exit(0);
 264                 }
 265                 setpgrp(0, getpid());
 266                 (void) close(s); (void)close(pv[0]);
 267                 dup2(pv[1], 2);
 268         }
 269         if (*pwd->pw_shell == '\0')
 270                 pwd->pw_shell = _PATH_BSHELL;
 271         if (f > 2)
 272                 (void) close(f);
 273         if (setlogin(pwd->pw_name) < 0)
 274                 syslog(LOG_ERR, "setlogin() failed: %m");
 275         (void) setgid((gid_t)pwd->pw_gid);
 276         initgroups(pwd->pw_name, pwd->pw_gid);
 277         (void) setuid((uid_t)pwd->pw_uid);
 278         (void)strcat(path, _PATH_DEFPATH);
 279         environ = envinit;
 280         strncat(homedir, pwd->pw_dir, sizeof(homedir)-6);
 281         strncat(shell, pwd->pw_shell, sizeof(shell)-7);
 282         strncat(username, pwd->pw_name, sizeof(username)-6);
 283         cp = strrchr(pwd->pw_shell, '/');
 284         if (cp)
 285                 cp++;
 286         else
 287                 cp = pwd->pw_shell;
 288         if (chdir(pwd->pw_dir) < 0) {
 289                 error("No remote directory.\n");
 290                 exit(1);
 291         }
 292         execl(pwd->pw_shell, cp, "-c", cmdbuf, 0);
 293         err(1, "%s", pwd->pw_shell);
 294 }
 295
 296 /*VARARGS1*/
 297 void
 298 error(fmt, a1, a2, a3)
 299         char *fmt;
 300         int a1, a2, a3;
 301 {
 302         char buf[BUFSIZ];
 303
 304         buf[0] = 1;
 305         (void) snprintf(buf+1, sizeof(buf) - 1, fmt, a1, a2, a3);
 306         (void) write(2, buf, strlen(buf));
 307 }
 308
 309 void
 310 getstr(buf, cnt, err)
 311         char *buf;
 312         int cnt;
 313         char *err;
 314 {
 315         char c;
 316
 317         do {
 318                 if (read(0, &c, 1) != 1)
 319                         exit(1);
 320                 *buf++ = c;
 321                 if (--cnt == 0) {
 322                         error("%s too long\n", err);
 323                         exit(1);
 324                 }
 325         } while (c != 0);
 326 }