1 /* $NetBSD: rexecd.c,v 1.26 2008/07/20 01:09:07 lukem Exp $ */ 2 3 /* 4 * Copyright (c) 1983, 1993 5 * The Regents of the University of California. All rights reserved. 6 * 7 * Redistribution and use in source and binary forms, with or without 8 * modification, are permitted provided that the following conditions 9 * are met: 10 * 1. Redistributions of source code must retain the above copyright 11 * notice, this list of conditions and the following disclaimer. 12 * 2. Redistributions in binary form must reproduce the above copyright 13 * notice, this list of conditions and the following disclaimer in the 14 * documentation and/or other materials provided with the distribution. 15 * 3. Neither the name of the University nor the names of its contributors 16 * may be used to endorse or promote products derived from this software 17 * without specific prior written permission. 18 * 19 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 20 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 21 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 22 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 23 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 24 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 25 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 26 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 27 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 28 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 29 * SUCH DAMAGE. 30 */ 31 32 #include <sys/cdefs.h> 33 #ifndef lint 34 __COPYRIGHT("@(#) Copyright (c) 1983, 1993\ 35 The Regents of the University of California. All rights reserved."); 36 #if 0 37 static char sccsid[] = "from: @(#)rexecd.c 8.1 (Berkeley) 6/4/93"; 38 #else 39 __RCSID("$NetBSD: rexecd.c,v 1.26 2008/07/20 01:09:07 lukem Exp $"); 40 #endif 41 #endif /* not lint */ 42 43 #include <sys/ioctl.h> 44 #include <sys/param.h> 45 #include <sys/socket.h> 46 #include <sys/syslog.h> 47 #include <sys/time.h> 48 49 #include <netinet/in.h> 50 51 #include <err.h> 52 #include <errno.h> 53 #include <netdb.h> 54 #include <paths.h> 55 #include <poll.h> 56 #include <pwd.h> 57 #include <signal.h> 58 #include <stdarg.h> 59 #include <stdio.h> 60 #include <stdlib.h> 61 #include <string.h> 62 #include <unistd.h> 63 64 #ifdef USE_PAM 65 #include <security/pam_appl.h> 66 #include <security/openpam.h> 67 #endif 68 69 int main(int, char *[]); 70 static void rexecd_errx(int, const char *, ...) 71 __attribute__((__noreturn__, __format__(__printf__, 2, 3))); 72 static void doit(struct sockaddr *) __dead; 73 static void getstr(char *, int, const char *); 74 static void usage(void) __dead; 75 76 #ifdef USE_PAM 77 static pam_handle_t *pamh; 78 static struct pam_conv pamc = { 79 openpam_nullconv, 80 NULL 81 }; 82 static int pam_flags = PAM_SILENT|PAM_DISALLOW_NULL_AUTHTOK; 83 static int pam_err; 84 #define pam_ok(err) ((pam_err = (err)) == PAM_SUCCESS) 85 #endif 86 87 extern char **environ; 88 static int dolog; 89 #ifndef USE_PAM 90 static char username[32 + 1] = "USER="; 91 static char logname[32 + 3 + 1] = "LOGNAME="; 92 static char homedir[PATH_MAX + 1] = "HOME="; 93 static char shell[PATH_MAX + 1] = "SHELL="; 94 static char path[sizeof(_PATH_DEFPATH) + sizeof("PATH=")] = "PATH="; 95 static char *envinit[] = { homedir, shell, path, username, logname, 0 }; 96 #endif 97 98 /* 99 * remote execute server: 100 * username\0 101 * password\0 102 * command\0 103 * data 104 */ 105 int 106 main(int argc, char *argv[]) 107 { 108 struct sockaddr_storage from; 109 socklen_t fromlen; 110 int ch; 111 112 while ((ch = getopt(argc, argv, "l")) != -1) 113 switch (ch) { 114 case 'l': 115 dolog = 1; 116 openlog("rexecd", LOG_PID, LOG_DAEMON); 117 break; 118 default: 119 usage(); 120 } 121 122 fromlen = sizeof(from); 123 if (getpeername(STDIN_FILENO, (struct sockaddr *)&from, &fromlen) < 0) 124 err(EXIT_FAILURE, "getpeername"); 125 126 if (((struct sockaddr *)&from)->sa_family == AF_INET6 && 127 IN6_IS_ADDR_V4MAPPED(&((struct sockaddr_in6 *)&from)->sin6_addr)) { 128 char hbuf[NI_MAXHOST]; 129 if (getnameinfo((struct sockaddr *)&from, fromlen, hbuf, 130 sizeof(hbuf), NULL, 0, NI_NUMERICHOST) != 0) { 131 (void)strlcpy(hbuf, "invalid", sizeof(hbuf)); 132 } 133 if (dolog) 134 syslog(LOG_ERR, 135 "malformed \"from\" address (v4 mapped, %s)", 136 hbuf); 137 return EXIT_FAILURE; 138 } 139 140 doit((struct sockaddr *)&from); 141 } 142 143 void 144 doit(struct sockaddr *fromp) 145 { 146 struct pollfd fds[2]; 147 char cmdbuf[NCARGS + 1]; 148 const char *cp; 149 char user[16], pass[16]; 150 char buf[BUFSIZ], sig; 151 struct passwd *pwd, pwres; 152 int s = -1; /* XXX gcc */ 153 int pv[2], pid, cc; 154 int one = 1; 155 in_port_t port; 156 char hostname[2 * MAXHOSTNAMELEN + 1]; 157 char pbuf[NI_MAXSERV]; 158 const int niflags = NI_NUMERICHOST | NI_NUMERICSERV; 159 #ifndef USE_PAM 160 char *namep; 161 #endif 162 char pwbuf[1024]; 163 164 (void)signal(SIGINT, SIG_DFL); 165 (void)signal(SIGQUIT, SIG_DFL); 166 (void)signal(SIGTERM, SIG_DFL); 167 (void)dup2(STDIN_FILENO, STDOUT_FILENO); 168 (void)dup2(STDIN_FILENO, STDERR_FILENO); 169 170 if (getnameinfo(fromp, fromp->sa_len, hostname, sizeof(hostname), 171 pbuf, sizeof(pbuf), niflags) != 0) { 172 if (dolog) 173 syslog(LOG_ERR, "malformed \"from\" address (af %d)", 174 fromp->sa_family); 175 exit(EXIT_FAILURE); 176 } 177 178 (void)alarm(60); 179 port = 0; 180 for (;;) { 181 char c; 182 if (read(STDIN_FILENO, &c, 1) != 1) { 183 if (dolog) 184 syslog(LOG_ERR, "initial read failed"); 185 exit(EXIT_FAILURE); 186 } 187 if (c == 0) 188 break; 189 port = port * 10 + c - '0'; 190 } 191 if (port != 0) { 192 s = socket(fromp->sa_family, SOCK_STREAM, 0); 193 if (s < 0) { 194 if (dolog) 195 syslog(LOG_ERR, "socket: %m"); 196 exit(EXIT_FAILURE); 197 } 198 (void)alarm(60); 199 switch (fromp->sa_family) { 200 case AF_INET: 201 ((struct sockaddr_in *)fromp)->sin_port = htons(port); 202 break; 203 case AF_INET6: 204 ((struct sockaddr_in6 *)fromp)->sin6_port = htons(port); 205 break; 206 default: 207 syslog(LOG_ERR, "unsupported address family"); 208 exit(EXIT_FAILURE); 209 } 210 if (connect(s, (struct sockaddr *)fromp, fromp->sa_len) < 0) { 211 if (dolog) 212 syslog(LOG_ERR, "connect: %m"); 213 exit(EXIT_FAILURE); 214 } 215 (void)alarm(0); 216 } 217 (void)alarm(60); 218 getstr(user, sizeof(user), "username"); 219 getstr(pass, sizeof(pass), "password"); 220 getstr(cmdbuf, sizeof(cmdbuf), "command"); 221 (void)alarm(0); 222 if (getpwnam_r(user, &pwres, pwbuf, sizeof(pwbuf), &pwd) != 0 || 223 pwd == NULL) { 224 if (dolog) 225 syslog(LOG_ERR, "no such user %s", user); 226 rexecd_errx(EXIT_FAILURE, "Login incorrect."); 227 } 228 #ifdef USE_PAM 229 if (!pam_ok(pam_start("rexecd", user, &pamc, &pamh)) || 230 !pam_ok(pam_set_item(pamh, PAM_RHOST, hostname)) || 231 !pam_ok(pam_set_item(pamh, PAM_AUTHTOK, pass))) { 232 if (dolog) 233 syslog(LOG_ERR, "PAM ERROR %s@%s (%s)", user, 234 hostname, pam_strerror(pamh, pam_err)); 235 rexecd_errx(EXIT_FAILURE, "Try again."); 236 } 237 if (!pam_ok(pam_authenticate(pamh, pam_flags)) || 238 !pam_ok(pam_acct_mgmt(pamh, pam_flags))) { 239 if (dolog) 240 syslog(LOG_ERR, "LOGIN REFUSED for %s@%s (%s)", user, 241 hostname, pam_strerror(pamh, pam_err)); 242 rexecd_errx(EXIT_FAILURE, "Password incorrect."); 243 } 244 #else 245 if (*pwd->pw_passwd != '\0') { 246 namep = crypt(pass, pwd->pw_passwd); 247 if (strcmp(namep, pwd->pw_passwd) != 0) { 248 if (dolog) 249 syslog(LOG_ERR, "incorrect password for %s", 250 user); 251 rexecd_errx(EXIT_FAILURE, 252 "Password incorrect.");/* XXX: wrong! */ 253 } 254 } else 255 (void)crypt("dummy password", "PA"); /* must always crypt */ 256 #endif 257 if (chdir(pwd->pw_dir) < 0) { 258 if (dolog) 259 syslog(LOG_ERR, "%s does not exist for %s", pwd->pw_dir, 260 user); 261 rexecd_errx(EXIT_FAILURE, "No remote directory."); 262 } 263 264 if (dolog) 265 syslog(LOG_INFO, "login from %s as %s", hostname, user); 266 (void)write(STDERR_FILENO, "\0", 1); 267 if (port) { 268 if (pipe(pv) < 0 || (pid = fork()) == -1) { 269 if (dolog) 270 syslog(LOG_ERR,"pipe or fork failed for %s: %m", 271 user); 272 rexecd_errx(EXIT_FAILURE, "Try again."); 273 } 274 if (pid) { 275 /* parent */ 276 #ifdef USE_PAM 277 (void)pam_end(pamh, pam_err); 278 #endif 279 (void)close(STDIN_FILENO); 280 (void)close(STDOUT_FILENO); 281 (void)close(STDERR_FILENO); 282 (void)close(pv[1]); 283 fds[0].fd = s; 284 fds[1].fd = pv[0]; 285 fds[0].events = fds[1].events = POLLIN; 286 if (ioctl(pv[1], FIONBIO, (char *)&one) < 0) 287 _exit(1); 288 /* should set s nbio! */ 289 do { 290 if (poll(fds, 2, 0) < 0) { 291 (void)close(s); 292 (void)close(pv[0]); 293 _exit(1); 294 } 295 if (fds[0].revents & POLLIN) { 296 if (read(s, &sig, 1) <= 0) 297 fds[0].events = 0; 298 else 299 (void)killpg(pid, sig); 300 } 301 if (fds[1].revents & POLLIN) { 302 cc = read(pv[0], buf, sizeof (buf)); 303 if (cc <= 0) { 304 (void)shutdown(s, SHUT_RDWR); 305 fds[1].events = 0; 306 } else 307 (void)write(s, buf, cc); 308 } 309 } while ((fds[0].events | fds[1].events) & POLLIN); 310 _exit(0); 311 } 312 /* child */ 313 (void)close(s); 314 (void)close(pv[0]); 315 if (dup2(pv[1], STDERR_FILENO) < 0) { 316 if (dolog) 317 syslog(LOG_ERR, "dup2 failed for %s", user); 318 rexecd_errx(EXIT_FAILURE, "Try again."); 319 } 320 } 321 if (*pwd->pw_shell == '\0') 322 pwd->pw_shell = __UNCONST(_PATH_BSHELL); 323 if (setsid() < 0 || 324 setlogin(pwd->pw_name) < 0 || 325 initgroups(pwd->pw_name, pwd->pw_gid) < 0 || 326 #ifdef USE_PAM 327 setgid((gid_t)pwd->pw_gid) < 0) { 328 #else 329 setgid((gid_t)pwd->pw_gid) < 0 || 330 setuid((uid_t)pwd->pw_uid) < 0) { 331 #endif 332 rexecd_errx(EXIT_FAILURE, "Try again."); 333 if (dolog) 334 syslog(LOG_ERR, "could not set permissions for %s: %m", 335 user); 336 exit(EXIT_FAILURE); 337 } 338 #ifdef USE_PAM 339 if (!pam_ok(pam_setcred(pamh, PAM_ESTABLISH_CRED))) 340 syslog(LOG_ERR, "pam_setcred() failed: %s", 341 pam_strerror(pamh, pam_err)); 342 (void)pam_setenv(pamh, "HOME", pwd->pw_dir, 1); 343 (void)pam_setenv(pamh, "SHELL", pwd->pw_shell, 1); 344 (void)pam_setenv(pamh, "USER", pwd->pw_name, 1); 345 (void)pam_setenv(pamh, "LOGNAME", pwd->pw_name, 1); 346 (void)pam_setenv(pamh, "PATH", _PATH_DEFPATH, 1); 347 environ = pam_getenvlist(pamh); 348 (void)pam_end(pamh, pam_err); 349 if (setuid((uid_t)pwd->pw_uid) < 0) { 350 if (dolog) 351 syslog(LOG_ERR, "could not set uid for %s: %m", 352 user); 353 rexecd_errx(EXIT_FAILURE, "Try again."); 354 } 355 #else 356 (void)strlcat(path, _PATH_DEFPATH, sizeof(path)); 357 environ = envinit; 358 (void)strlcat(homedir, pwd->pw_dir, sizeof(homedir)); 359 (void)strlcat(shell, pwd->pw_shell, sizeof(shell)); 360 (void)strlcat(username, pwd->pw_name, sizeof(username)); 361 (void)strlcat(logname, pwd->pw_name, sizeof(logname)); 362 #endif 363 364 cp = strrchr(pwd->pw_shell, '/'); 365 if (cp) 366 cp++; 367 else 368 cp = pwd->pw_shell; 369 if (dolog) 370 syslog(LOG_INFO, "running command for %s: %s", user, cmdbuf); 371 (void)execl(pwd->pw_shell, cp, "-c", cmdbuf, NULL); 372 if (dolog) 373 syslog(LOG_ERR, "execl failed for %s: %m", user); 374 err(EXIT_FAILURE, "%s", pwd->pw_shell); 375 } 376 377 void 378 rexecd_errx(int ex, const char *fmt, ...) 379 { 380 char buf[BUFSIZ]; 381 va_list ap; 382 ssize_t len; 383 384 va_start(ap, fmt); 385 buf[0] = 1; 386 len = vsnprintf(buf + 1, sizeof(buf) - 1, fmt, ap) + 1; 387 buf[len++] = '\n'; 388 (void)write(STDERR_FILENO, buf, len); 389 va_end(ap); 390 exit(ex); 391 } 392 393 void 394 getstr(char *buf, int cnt, const char *emsg) 395 { 396 char c; 397 398 do { 399 if (read(STDIN_FILENO, &c, 1) != 1) 400 exit(EXIT_FAILURE); 401 *buf++ = c; 402 if (--cnt == 0) 403 rexecd_errx(EXIT_FAILURE, "%s too long", emsg); 404 } while (c != 0); 405 } 406 407 static void 408 usage(void) 409 { 410 (void)fprintf(stderr, "Usage: %s [-l]\n", getprogname()); 411 exit(EXIT_FAILURE); 412 } 413