/*- * Copyright (c) 1988, 1989, 1992, 1993, 1994 * The Regents of the University of California. All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * 3. All advertising materials mentioning features or use of this software * must display the following acknowledgement: * This product includes software developed by the University of * California, Berkeley and its contributors. * 4. Neither the name of the University nor the names of its contributors * may be used to endorse or promote products derived from this software * without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF * SUCH DAMAGE. */ #ifndef lint static char copyright[] = "@(#) Copyright (c) 1988, 1989, 1992, 1993, 1994\n\ The Regents of the University of California. All rights reserved.\n"; #endif /* not lint */ #ifndef lint /* from: static char sccsid[] = "@(#)rshd.c 8.2 (Berkeley) 4/6/94"; */ static char *rcsid = "$Id: rshd.c,v 1.16 1997/02/13 22:32:46 deraadt Exp $"; #endif /* not lint */ /* * remote shell server: * [port]\0 * remuser\0 * locuser\0 * command\0 * data */ #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include int keepalive = 1; int check_all; int log_success; /* If TRUE, log all successful accesses */ int sent_null; void doit __P((struct sockaddr_in *)); void error __P((const char *, ...)); void getstr __P((char *, int, char *)); int local_domain __P((char *)); char *topdomain __P((char *)); void usage __P((void)); #ifdef KERBEROS #include #include #define VERSION_SIZE 9 #define SECURE_MESSAGE "This rsh session is using DES encryption for all transmissions.\r\n" #define OPTIONS "alnkvxL" char authbuf[sizeof(AUTH_DAT)]; char tickbuf[sizeof(KTEXT_ST)]; int doencrypt, use_kerberos, vacuous; Key_schedule schedule; #else #define OPTIONS "alnL" #endif int main(argc, argv) int argc; char *argv[]; { extern int __check_rhosts_file; struct linger linger; int ch, on = 1, fromlen; struct sockaddr_in from; openlog("rshd", LOG_PID | LOG_ODELAY, LOG_DAEMON); opterr = 0; while ((ch = getopt(argc, argv, OPTIONS)) != -1) switch (ch) { case 'a': check_all = 1; break; case 'l': __check_rhosts_file = 0; break; case 'n': keepalive = 0; break; #ifdef KERBEROS case 'k': use_kerberos = 1; break; case 'v': vacuous = 1; break; #ifdef CRYPT case 'x': doencrypt = 1; break; #endif #endif case 'L': log_success = 1; break; case '?': default: usage(); break; } argc -= optind; argv += optind; #ifdef KERBEROS if (use_kerberos && vacuous) { syslog(LOG_ERR, "only one of -k and -v allowed"); exit(2); } #ifdef CRYPT if (doencrypt && !use_kerberos) { syslog(LOG_ERR, "-k is required for -x"); exit(2); } #endif #endif fromlen = sizeof (from); if (getpeername(0, (struct sockaddr *)&from, &fromlen) < 0) { syslog(LOG_ERR, "getpeername: %m"); _exit(1); } if (keepalive && setsockopt(0, SOL_SOCKET, SO_KEEPALIVE, (char *)&on, sizeof(on)) < 0) syslog(LOG_WARNING, "setsockopt (SO_KEEPALIVE): %m"); linger.l_onoff = 1; linger.l_linger = 60; /* XXX */ if (setsockopt(0, SOL_SOCKET, SO_LINGER, (char *)&linger, sizeof (linger)) < 0) syslog(LOG_WARNING, "setsockopt (SO_LINGER): %m"); doit(&from); /* NOTREACHED */ } char username[20] = "USER="; char logname[23] = "LOGNAME="; char homedir[64] = "HOME="; char shell[64] = "SHELL="; char path[100] = "PATH="; char *envinit[] = {homedir, shell, path, logname, username, 0}; char **environ; void doit(fromp) struct sockaddr_in *fromp; { extern char *__rcmd_errstr; /* syslog hook from libc/net/rcmd.c. */ struct hostent *hp; struct passwd *pwd; u_short port; fd_set ready, readfrom; int cc, nfd, pv[2], pid, s; int one = 1; char *hostname, *errorstr, *errorhost; char *cp, sig, buf[BUFSIZ]; char cmdbuf[NCARGS+1], locuser[16], remuser[16]; char remotehost[2 * MAXHOSTNAMELEN + 1]; char hostnamebuf[2 * MAXHOSTNAMELEN + 1]; #ifdef KERBEROS AUTH_DAT *kdata = (AUTH_DAT *) NULL; KTEXT ticket = (KTEXT) NULL; char instance[INST_SZ], version[VERSION_SIZE]; struct sockaddr_in fromaddr; int rc; long authopts; int pv1[2], pv2[2]; fd_set wready, writeto; fromaddr = *fromp; #endif (void) signal(SIGINT, SIG_DFL); (void) signal(SIGQUIT, SIG_DFL); (void) signal(SIGTERM, SIG_DFL); #ifdef DEBUG { int t = open(_PATH_TTY, 2); if (t >= 0) { ioctl(t, TIOCNOTTY, (char *)0); (void) close(t); } } #endif fromp->sin_port = ntohs((u_short)fromp->sin_port); if (fromp->sin_family != AF_INET) { syslog(LOG_ERR, "malformed \"from\" address (af %d)\n", fromp->sin_family); exit(1); } #ifdef IP_OPTIONS { struct ipoption opts; int optsize = sizeof(opts), ipproto, i; struct protoent *ip; if ((ip = getprotobyname("ip")) != NULL) ipproto = ip->p_proto; else ipproto = IPPROTO_IP; if (!getsockopt(0, ipproto, IP_OPTIONS, (char *)&opts, &optsize) && optsize != 0) { for (i = 0; (void *)&opts.ipopt_list[i] - (void *)&opts < optsize; ) { u_char c = (u_char)opts.ipopt_list[i]; if (c == IPOPT_LSRR || c == IPOPT_SSRR) exit(1); if (c == IPOPT_EOL) break; i += (c == IPOPT_NOP) ? 1 : (u_char)opts.ipopt_list[i+1]; } } } #endif #ifdef KERBEROS if (!use_kerberos) #endif if (fromp->sin_port >= IPPORT_RESERVED || fromp->sin_port < IPPORT_RESERVED/2) { syslog(LOG_NOTICE|LOG_AUTH, "Connection from %s on illegal port %u", inet_ntoa(fromp->sin_addr), fromp->sin_port); exit(1); } (void) alarm(60); port = 0; for (;;) { char c; if ((cc = read(STDIN_FILENO, &c, 1)) != 1) { if (cc < 0) syslog(LOG_NOTICE, "read: %m"); shutdown(0, 1+1); exit(1); } if (c== 0) break; port = port * 10 + c - '0'; } (void) alarm(0); if (port != 0) { int lport = IPPORT_RESERVED - 1; s = rresvport(&lport); if (s < 0) { syslog(LOG_ERR, "can't get stderr port: %m"); exit(1); } #ifdef KERBEROS if (!use_kerberos) #endif if (port >= IPPORT_RESERVED || port < IPPORT_RESERVED/2) { syslog(LOG_ERR, "2nd port not reserved\n"); exit(1); } fromp->sin_port = htons(port); if (connect(s, (struct sockaddr *)fromp, sizeof (*fromp)) < 0) { syslog(LOG_INFO, "connect second port %d: %m", port); exit(1); } } #ifdef KERBEROS if (vacuous) { error("rshd: remote host requires Kerberos authentication\n"); exit(1); } #endif #ifdef notdef /* from inetd, socket is already on 0, 1, 2 */ dup2(f, 0); dup2(f, 1); dup2(f, 2); #endif errorstr = NULL; hp = gethostbyaddr((char *)&fromp->sin_addr, sizeof (struct in_addr), fromp->sin_family); if (hp) { /* * If name returned by gethostbyaddr is in our domain, * attempt to verify that we haven't been fooled by someone * in a remote net; look up the name and check that this * address corresponds to the name. */ hostname = hp->h_name; #ifdef KERBEROS if (!use_kerberos) #endif if (check_all || local_domain(hp->h_name)) { strncpy(remotehost, hp->h_name, sizeof(remotehost) - 1); remotehost[sizeof(remotehost) - 1] = 0; errorhost = remotehost; hp = gethostbyname(remotehost); if (hp == NULL) { syslog(LOG_INFO, "Couldn't look up address for %s", remotehost); errorstr = "Couldn't look up address for your host (%s)\n"; hostname = inet_ntoa(fromp->sin_addr); } else for (; ; hp->h_addr_list++) { if (hp->h_addr_list[0] == NULL) { syslog(LOG_NOTICE, "Host addr %s not listed for host %s", inet_ntoa(fromp->sin_addr), hp->h_name); errorstr = "Host address mismatch for %s\n"; hostname = inet_ntoa(fromp->sin_addr); break; } if (!bcmp(hp->h_addr_list[0], (caddr_t)&fromp->sin_addr, sizeof(fromp->sin_addr))) { hostname = hp->h_name; break; } } } hostname = strncpy(hostnamebuf, hostname, sizeof(hostnamebuf) - 1); } else errorhost = hostname = strncpy(hostnamebuf, inet_ntoa(fromp->sin_addr), sizeof(hostnamebuf) - 1); hostnamebuf[sizeof(hostnamebuf) - 1] = '\0'; #ifdef KERBEROS if (use_kerberos) { kdata = (AUTH_DAT *) authbuf; ticket = (KTEXT) tickbuf; authopts = 0L; strcpy(instance, "*"); version[VERSION_SIZE - 1] = '\0'; #ifdef CRYPT if (doencrypt) { struct sockaddr_in local_addr; rc = sizeof(local_addr); if (getsockname(0, (struct sockaddr *)&local_addr, &rc) < 0) { syslog(LOG_ERR, "getsockname: %m"); error("rlogind: getsockname: %m"); exit(1); } authopts = KOPT_DO_MUTUAL; rc = krb_recvauth(authopts, 0, ticket, "rcmd", instance, &fromaddr, &local_addr, kdata, "", schedule, version); desrw_set_key(kdata->session, schedule); } else #endif rc = krb_recvauth(authopts, 0, ticket, "rcmd", instance, &fromaddr, (struct sockaddr_in *) 0, kdata, "", (struct des_ks_struct *) 0, version); if (rc != KSUCCESS) { error("Kerberos authentication failure: %s\n", krb_err_txt[rc]); exit(1); } } else #endif getstr(remuser, sizeof(remuser), "remuser"); getstr(locuser, sizeof(locuser), "locuser"); getstr(cmdbuf, sizeof(cmdbuf), "command"); setpwent(); pwd = getpwnam(locuser); if (pwd == NULL) { syslog(LOG_INFO|LOG_AUTH, "%s@%s as %s: unknown login. cmd='%.80s'", remuser, hostname, locuser, cmdbuf); if (errorstr == NULL) errorstr = "Login incorrect.\n"; goto fail; } setegid(pwd->pw_gid); seteuid(pwd->pw_uid); if (chdir(pwd->pw_dir) < 0) { (void) chdir("/"); #ifdef notdef syslog(LOG_INFO|LOG_AUTH, "%s@%s as %s: no home directory. cmd='%.80s'", remuser, hostname, locuser, cmdbuf); error("No remote directory.\n"); exit(1); #endif } seteuid(0); setegid(0); /* XXX use a saved gid instead? */ #ifdef KERBEROS if (use_kerberos) { if (pwd->pw_passwd != 0 && *pwd->pw_passwd != '\0') { if (kuserok(kdata, locuser) != 0) { syslog(LOG_INFO|LOG_AUTH, "Kerberos rsh denied to %s.%s@%s", kdata->pname, kdata->pinst, kdata->prealm); error("Permission denied.\n"); exit(1); } } } else #endif if (errorstr || pwd->pw_passwd != 0 && *pwd->pw_passwd != '\0' && iruserok(fromp->sin_addr.s_addr, pwd->pw_uid == 0, remuser, locuser) < 0) { if (__rcmd_errstr) syslog(LOG_INFO|LOG_AUTH, "%s@%s as %s: permission denied (%s). cmd='%.80s'", remuser, hostname, locuser, __rcmd_errstr, cmdbuf); else syslog(LOG_INFO|LOG_AUTH, "%s@%s as %s: permission denied. cmd='%.80s'", remuser, hostname, locuser, cmdbuf); fail: if (errorstr == NULL) errorstr = "Permission denied.\n"; error(errorstr, errorhost); exit(1); } if (pwd->pw_uid && !access(_PATH_NOLOGIN, F_OK)) { error("Logins currently disabled.\n"); exit(1); } (void) write(STDERR_FILENO, "\0", 1); sent_null = 1; if (port) { if (pipe(pv) < 0) { error("Can't make pipe.\n"); exit(1); } #ifdef CRYPT #ifdef KERBEROS if (doencrypt) { if (pipe(pv1) < 0) { error("Can't make 2nd pipe.\n"); exit(1); } if (pipe(pv2) < 0) { error("Can't make 3rd pipe.\n"); exit(1); } } #endif #endif pid = fork(); if (pid == -1) { error("Can't fork; try again.\n"); exit(1); } if (pid) { #ifdef CRYPT #ifdef KERBEROS if (doencrypt) { static char msg[] = SECURE_MESSAGE; (void) close(pv1[1]); (void) close(pv2[1]); des_write(s, msg, sizeof(msg) - 1); } else #endif #endif { (void) close(0); (void) close(1); } (void) close(2); (void) close(pv[1]); FD_ZERO(&readfrom); FD_SET(s, &readfrom); FD_SET(pv[0], &readfrom); if (pv[0] > s) nfd = pv[0]; else nfd = s; #ifdef CRYPT #ifdef KERBEROS if (doencrypt) { FD_ZERO(&writeto); FD_SET(pv2[0], &writeto); FD_SET(pv1[0], &readfrom); nfd = MAX(nfd, pv2[0]); nfd = MAX(nfd, pv1[0]); } else #endif #endif ioctl(pv[0], FIONBIO, (char *)&one); /* should set s nbio! */ nfd++; do { ready = readfrom; #ifdef CRYPT #ifdef KERBEROS if (doencrypt) { wready = writeto; if (select(nfd, &ready, &wready, (fd_set *) 0, (struct timeval *) 0) < 0) break; } else #endif #endif if (select(nfd, &ready, (fd_set *)0, (fd_set *)0, (struct timeval *)0) < 0) break; if (FD_ISSET(s, &ready)) { int ret; #ifdef CRYPT #ifdef KERBEROS if (doencrypt) ret = des_read(s, &sig, 1); else #endif #endif ret = read(s, &sig, 1); if (ret <= 0) FD_CLR(s, &readfrom); else killpg(pid, sig); } if (FD_ISSET(pv[0], &ready)) { errno = 0; cc = read(pv[0], buf, sizeof(buf)); if (cc <= 0) { shutdown(s, 1+1); FD_CLR(pv[0], &readfrom); } else { #ifdef CRYPT #ifdef KERBEROS if (doencrypt) (void) des_write(s, buf, cc); else #endif #endif (void) write(s, buf, cc); } } #ifdef CRYPT #ifdef KERBEROS if (doencrypt && FD_ISSET(pv1[0], &ready)) { errno = 0; cc = read(pv1[0], buf, sizeof(buf)); if (cc <= 0) { shutdown(pv1[0], 1+1); FD_CLR(pv1[0], &readfrom); } else (void) des_write(STDOUT_FILENO, buf, cc); } if (doencrypt && FD_ISSET(pv2[0], &wready)) { errno = 0; cc = des_read(STDIN_FILENO, buf, sizeof(buf)); if (cc <= 0) { shutdown(pv2[0], 1+1); FD_CLR(pv2[0], &writeto); } else (void) write(pv2[0], buf, cc); } #endif #endif } while (FD_ISSET(s, &readfrom) || #ifdef CRYPT #ifdef KERBEROS (doencrypt && FD_ISSET(pv1[0], &readfrom)) || #endif #endif FD_ISSET(pv[0], &readfrom)); exit(0); } setpgrp(0, getpid()); (void) close(s); (void) close(pv[0]); #ifdef CRYPT #ifdef KERBEROS if (doencrypt) { close(pv1[0]); close(pv2[0]); dup2(pv1[1], 1); dup2(pv2[1], 0); close(pv1[1]); close(pv2[1]); } #endif #endif dup2(pv[1], 2); close(pv[1]); } if (*pwd->pw_shell == '\0') pwd->pw_shell = _PATH_BSHELL; #if BSD > 43 if (setlogin(pwd->pw_name) < 0) syslog(LOG_ERR, "setlogin() failed: %m"); #endif (void) setegid((gid_t)pwd->pw_gid); (void) setgid((gid_t)pwd->pw_gid); initgroups(pwd->pw_name, pwd->pw_gid); (void) seteuid((uid_t)pwd->pw_uid); (void) setuid((uid_t)pwd->pw_uid); environ = envinit; strncat(homedir, pwd->pw_dir, sizeof(homedir)-6); strcat(path, _PATH_DEFPATH); strncat(shell, pwd->pw_shell, sizeof(shell)-7); strncat(logname, pwd->pw_name, sizeof(logname)-9); strncat(username, pwd->pw_name, sizeof(username)-6); cp = strrchr(pwd->pw_shell, '/'); if (cp) cp++; else cp = pwd->pw_shell; endpwent(); if (log_success || pwd->pw_uid == 0) { #ifdef KERBEROS if (use_kerberos) syslog(LOG_INFO|LOG_AUTH, "Kerberos shell from %s.%s@%s on %s as %s, cmd='%.80s'", kdata->pname, kdata->pinst, kdata->prealm, hostname, locuser, cmdbuf); else #endif syslog(LOG_INFO|LOG_AUTH, "%s@%s as %s: cmd='%.80s'", remuser, hostname, locuser, cmdbuf); } execl(pwd->pw_shell, cp, "-c", cmdbuf, 0); perror(pwd->pw_shell); exit(1); } /* * Report error to client. Note: can't be used until second socket has * connected to client, or older clients will hang waiting for that * connection first. */ #if __STDC__ #include #else #include #endif void #if __STDC__ error(const char *fmt, ...) #else error(fmt, va_alist) char *fmt; va_dcl #endif { va_list ap; int len; char *bp, buf[BUFSIZ]; #if __STDC__ va_start(ap, fmt); #else va_start(ap); #endif bp = buf; if (sent_null == 0) { *bp++ = 1; len = 1; } else len = 0; (void)vsnprintf(bp, sizeof(buf) - 1, fmt, ap); (void)write(STDERR_FILENO, buf, len + strlen(bp)); } void getstr(buf, cnt, err) char *buf, *err; int cnt; { char c; do { if (read(STDIN_FILENO, &c, 1) != 1) exit(1); *buf++ = c; if (--cnt == 0) { error("%s too long\n", err); exit(1); } } while (c != 0); } /* * Check whether host h is in our local domain, * defined as sharing the last two components of the domain part, * or the entire domain part if the local domain has only one component. * If either name is unqualified (contains no '.'), * assume that the host is local, as it will be * interpreted as such. */ int local_domain(h) char *h; { char localhost[MAXHOSTNAMELEN]; char *p1, *p2; localhost[0] = 0; (void) gethostname(localhost, sizeof(localhost)); p1 = topdomain(localhost); p2 = topdomain(h); if (p1 == NULL || p2 == NULL || !strcasecmp(p1, p2)) return (1); return (0); } char * topdomain(h) char *h; { char *p, *maybe = NULL; int dots = 0; for (p = h + strlen(h); p >= h; p--) { if (*p == '.') { if (++dots == 2) return (p); maybe = p; } } return (maybe); } void usage() { syslog(LOG_ERR, "usage: rshd [-%s]", OPTIONS); exit(2); }