/* $OpenBSD: rshd.c,v 1.53 2009/10/27 23:59:31 deraadt Exp $ */ /*- * 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. 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. */ /* * 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 #include #include #include #include #include int keepalive = 1; int check_all; int log_success; /* If TRUE, log all successful accesses */ int sent_null; login_cap_t *lc; void doit(struct sockaddr *); void error(const char *, ...); void getstr(char *, int, char *); int local_domain(char *); char *topdomain(char *); void usage(void); #ifdef KERBEROS #include #include #define VERSION_SIZE 9 #define SECURE_MESSAGE "This rsh session is using DES encryption for all transmissions.\r\n" #ifdef CRYPT #define OPTIONS "alnkvxL" #else #define OPTIONS "alnkvL" #endif char authbuf[sizeof(AUTH_DAT)]; char tickbuf[sizeof(KTEXT_ST)]; int doencrypt, use_kerberos, vacuous; des_key_schedule schedule; #ifdef CRYPT int des_read(int, char *, int); int des_write(int, char *, int); void desrw_clear_key(); void desrw_set_key(des_cblock *, des_key_schedule *); #endif #else #define OPTIONS "alnL" #endif #define P_SOCKREAD 0 #define P_PIPEREAD 1 #define P_CRYPTREAD 2 #define P_CRYPTWRITE 3 int main(int argc, char *argv[]) { extern int __check_rhosts_file; struct linger linger; int ch, on = 1; socklen_t fromlen; struct sockaddr_storage 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(STDIN_FILENO, (struct sockaddr *)&from, &fromlen) < 0) { /* syslog(LOG_ERR, "getpeername: %m"); */ exit(1); } if (keepalive && setsockopt(STDIN_FILENO, 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(STDIN_FILENO, SOL_SOCKET, SO_LINGER, (char *)&linger, sizeof (linger)) < 0) syslog(LOG_WARNING, "setsockopt (SO_LINGER): %m"); doit((struct sockaddr *)&from); /* NOTREACHED */ exit(0); } char *envinit[1] = { 0 }; extern char **environ; void doit(struct sockaddr *fromp) { extern char *__rcmd_errstr; /* syslog hook from libc/net/rcmd.c. */ struct addrinfo hints, *res, *res0; int gaierror; struct passwd *pwd; u_short port; in_port_t *portp; struct pollfd pfd[4]; int cc, nfd, pv[2], s = 0, one = 1; pid_t pid; char *hostname, *errorstr, *errorhost = (char *) NULL; char *cp, sig, buf[BUFSIZ]; char cmdbuf[NCARGS+1], locuser[_PW_NAME_LEN+1], remuser[_PW_NAME_LEN+1]; char remotehost[2 * MAXHOSTNAMELEN + 1]; char hostnamebuf[2 * MAXHOSTNAMELEN + 1]; char naddr[NI_MAXHOST]; char saddr[NI_MAXHOST]; char raddr[NI_MAXHOST]; char pbuf[NI_MAXSERV]; auth_session_t *as; const int niflags = NI_NUMERICHOST | NI_NUMERICSERV; #ifdef KERBEROS AUTH_DAT *kdata = (AUTH_DAT *) NULL; KTEXT ticket = (KTEXT) NULL; char instance[INST_SZ], version[VERSION_SIZE]; struct sockaddr_storage fromaddr; int rc; long authopts; #ifdef CRYPT int pv1[2], pv2[2]; #endif if (sizeof(fromaddr) < fromp->sa_len) { syslog(LOG_ERR, "malformed \"from\" address (af %d)", fromp->sa_family); exit(1); } memcpy(&fromaddr, fromp, fromp->sa_len); #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 switch (fromp->sa_family) { case AF_INET: portp = &((struct sockaddr_in *)fromp)->sin_port; break; case AF_INET6: portp = &((struct sockaddr_in6 *)fromp)->sin6_port; break; default: syslog(LOG_ERR, "malformed \"from\" address (af %d)", fromp->sa_family); exit(1); } if (getnameinfo(fromp, fromp->sa_len, naddr, sizeof(naddr), pbuf, sizeof(pbuf), niflags) != 0) { syslog(LOG_ERR, "malformed \"from\" address (af %d)", fromp->sa_family); exit(1); } #ifdef IP_OPTIONS if (fromp->sa_family == AF_INET) { struct ipoption opts; socklen_t optsize = sizeof(opts); int ipproto, i; struct protoent *ip; if ((ip = getprotobyname("ip")) != NULL) ipproto = ip->p_proto; else ipproto = IPPROTO_IP; if (!getsockopt(STDIN_FILENO, 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 (ntohs(*portp) >= IPPORT_RESERVED || ntohs(*portp) < IPPORT_RESERVED/2) { syslog(LOG_NOTICE|LOG_AUTH, "Connection from %s on illegal port %u", naddr, ntohs(*portp)); 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(STDIN_FILENO, SHUT_RDWR); exit(1); } if (c == 0) break; port = port * 10 + c - '0'; } (void) alarm(0); if (port != 0) { int lport; #ifdef KERBEROS if (!use_kerberos) #endif if (port >= IPPORT_RESERVED || port < IPPORT_RESERVED/2) { syslog(LOG_ERR, "2nd port not reserved"); exit(1); } *portp = htons(port); lport = IPPORT_RESERVED - 1; s = rresvport_af(&lport, fromp->sa_family); if (s < 0) { syslog(LOG_ERR, "can't get stderr port: %m"); exit(1); } if (connect(s, (struct sockaddr *)fromp, fromp->sa_len) < 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; if (getnameinfo(fromp, fromp->sa_len, saddr, sizeof(saddr), NULL, 0, NI_NAMEREQD)== 0) { /* * If name returned by getnameinfo 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 = saddr; res0 = NULL; #ifdef KERBEROS if (!use_kerberos) #endif if (check_all || local_domain(saddr)) { strlcpy(remotehost, saddr, sizeof(remotehost)); errorhost = remotehost; memset(&hints, 0, sizeof(hints)); hints.ai_family = fromp->sa_family; hints.ai_socktype = SOCK_STREAM; hints.ai_flags = AI_CANONNAME; gaierror = getaddrinfo(remotehost, pbuf, &hints, &res0); if (gaierror) { syslog(LOG_INFO, "Couldn't look up address for %s: %s", remotehost, gai_strerror(gaierror)); errorstr = "Couldn't look up address for your host (%s)\n"; hostname = naddr; } else { for (res = res0; res; res = res->ai_next) { if (res->ai_family != fromp->sa_family) continue; if (res->ai_addrlen != fromp->sa_len) continue; if (getnameinfo(res->ai_addr, res->ai_addrlen, raddr, sizeof(raddr), NULL, 0, niflags) == 0 && strcmp(naddr, raddr) == 0) { hostname = res->ai_canonname ? res->ai_canonname : saddr; break; } } if (res == NULL) { syslog(LOG_NOTICE, "Host addr %s not listed for host %s", naddr, res0->ai_canonname ? res0->ai_canonname : saddr); errorstr = "Host address mismatch for %s\n"; hostname = naddr; } } } strlcpy(hostnamebuf, hostname, sizeof(hostnamebuf)); hostname = hostnamebuf; if (res0) freeaddrinfo(res0); } else strlcpy(hostnamebuf, naddr, sizeof(hostnamebuf)); errorhost = hostname = hostnamebuf; #ifdef KERBEROS if (use_kerberos) { kdata = (AUTH_DAT *) authbuf; ticket = (KTEXT) tickbuf; authopts = 0L; strlcpy(instance, "*", sizeof instance); version[VERSION_SIZE - 1] = '\0'; #ifdef CRYPT if (doencrypt) { struct sockaddr_in local_addr; rc = sizeof(local_addr); if (getsockname(STDIN_FILENO, (struct sockaddr *)&local_addr, &rc) < 0) { syslog(LOG_ERR, "getsockname: %m"); error("rshd: getsockname: %m"); exit(1); } authopts = KOPT_DO_MUTUAL; rc = krb_recvauth(authopts, 0, ticket, "rcmd", instance, (struct sockaddr_in *)&fromaddr, &local_addr, kdata, "", schedule, version); desrw_set_key(&kdata->session, &schedule); } else #endif rc = krb_recvauth(authopts, 0, ticket, "rcmd", instance, (struct sockaddr_in *)&fromaddr, NULL, kdata, "", NULL, version); if (rc != KSUCCESS) { error("Kerberos authentication failure: %s\n", krb_get_err_text(rc)); exit(1); } } else #endif getstr(remuser, sizeof(remuser), "remuser"); getstr(locuser, sizeof(locuser), "locuser"); getstr(cmdbuf, sizeof(cmdbuf), "command"); 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 = "Permission denied.\n"; goto fail; } lc = login_getclass(pwd->pw_class); if (lc == NULL) { syslog(LOG_INFO|LOG_AUTH, "%s@%s as %s: unknown class. cmd='%.80s'", remuser, hostname, locuser, cmdbuf); if (errorstr == NULL) errorstr = "Login incorrect.\n"; goto fail; } as = auth_open(); if (as == NULL || auth_setpwd(as, pwd) != 0) { syslog(LOG_INFO|LOG_AUTH, "%s@%s as %s: unable to allocate memory. cmd='%.80s'", remuser, hostname, locuser, cmdbuf); if (errorstr == NULL) errorstr = "Cannot allocate memory.\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_sa(fromp, fromp->sa_len, 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) auth_checknologin(lc); (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(STDIN_FILENO); (void) close(STDOUT_FILENO); } (void) close(STDERR_FILENO); (void) close(pv[1]); pfd[P_SOCKREAD].fd = s; pfd[P_SOCKREAD].events = POLLIN; pfd[P_PIPEREAD].fd = pv[0]; pfd[P_PIPEREAD].events = POLLIN; nfd = 2; #ifdef CRYPT #ifdef KERBEROS if (doencrypt) { pfd[P_CRYPTREAD].fd = pv1[0]; pfd[P_CRYPTREAD].events = POLLIN; pfd[P_CRYPTWRITE].fd = pv2[0]; pfd[P_CRYPTWRITE].events = POLLOUT; nfd += 2; } else #endif #endif ioctl(pv[0], FIONBIO, (char *)&one); /* should set s nbio! */ do { if (poll(pfd, nfd, INFTIM) < 0) break; if (pfd[P_SOCKREAD].revents & POLLIN) { 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) pfd[P_SOCKREAD].revents = 0; else killpg(pid, sig); } if (pfd[P_PIPEREAD].revents & POLLIN) { errno = 0; cc = read(pv[0], buf, sizeof(buf)); if (cc <= 0) { shutdown(s, SHUT_RDWR); pfd[P_PIPEREAD].revents = 0; } 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 && (pfd[P_CRYPTREAD].revents & POLLIN)) { errno = 0; cc = read(pv1[0], buf, sizeof(buf)); if (cc <= 0) { shutdown(pv1[0], SHUT_RDWR); pfd[P_CRYPTREAD].revents = 0; } else (void) des_write(STDOUT_FILENO, buf, cc); } if (doencrypt && (pfd[P_CRYPTWRITE].revents & POLLIN)) { errno = 0; cc = des_read(STDIN_FILENO, buf, sizeof(buf)); if (cc <= 0) { shutdown(pv2[0], SHUT_RDWR); pfd[P_CRYPTWRITE].revents = 0; } else (void) write(pv2[0], buf, cc); } #endif #endif } while ((pfd[P_SOCKREAD].revents & POLLIN) || #ifdef CRYPT #ifdef KERBEROS (doencrypt && (pfd[P_CRYPTREAD].revents & POLLIN)) || #endif #endif (pfd[P_PIPEREAD].revents & POLLIN)); exit(0); } setsid(); (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]); } else setsid(); if (*pwd->pw_shell == '\0') pwd->pw_shell = _PATH_BSHELL; environ = envinit; if (setenv("HOME", pwd->pw_dir, 1) == -1 || setenv("SHELL", pwd->pw_shell, 1) == -1 || setenv("USER", pwd->pw_name, 1) == -1 || setenv("LOGNAME", pwd->pw_name, 1) == -1) errx(1, "cannot setup environment"); if (setusercontext(lc, pwd, pwd->pw_uid, LOGIN_SETALL)) errx(1, "cannot set user context"); if (auth_approval(as, lc, pwd->pw_name, "rsh") <= 0) errx(1, "approval failure"); auth_close(as); login_close(lc); 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, (char *)NULL); 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. */ void error(const char *fmt, ...) { va_list ap; int len; char *bp, buf[BUFSIZ]; va_start(ap, fmt); bp = buf; if (sent_null == 0) { *bp++ = 1; len = 1; } else len = 0; (void)vsnprintf(bp, sizeof(buf) - len, fmt, ap); (void)write(STDERR_FILENO, buf, len + strlen(bp)); va_end(ap); } void getstr(char *buf, int cnt, char *err) { 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(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(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(void) { syslog(LOG_ERR, "usage: rshd [-%s]", OPTIONS); exit(2); }