/*- * 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 const 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 #if 0 static const char sccsid[] = "@(#)rshd.c 8.2 (Berkeley) 4/6/94"; #endif static const char rcsid[] = "$FreeBSD: head/libexec/rshd/rshd.c 91749 2002-03-06 15:23:18Z des $"; #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 #include #include #include #include #ifdef USE_PAM #include #include static int export_pam_environment(void); static int ok_to_export(const char *); static pam_handle_t *pamh; static char **environ_pam; #define PAM_END { \ if ((retcode = pam_setcred(pamh, PAM_DELETE_CRED)) != PAM_SUCCESS) \ syslog(LOG_ERR|LOG_AUTH, "pam_setcred: %s", pam_strerror(pamh, retcode)); \ if ((retcode = pam_close_session(pamh,0)) != PAM_SUCCESS) \ syslog(LOG_ERR|LOG_AUTH, "pam_close_session: %s", pam_strerror(pamh, retcode)); \ if ((retcode = pam_end(pamh, retcode)) != PAM_SUCCESS) \ syslog(LOG_ERR|LOG_AUTH, "pam_end: %s", pam_strerror(pamh, retcode)); \ } #endif /* USE_PAM */ /* wrapper for KAME-special getnameinfo() */ #ifndef NI_WITHSCOPEID #define NI_WITHSCOPEID 0 #endif int keepalive = 1; int log_success; /* If TRUE, log all successful accesses */ int sent_null; int no_delay; #ifdef CRYPT int doencrypt = 0; #endif union sockunion { struct sockinet { u_char si_len; u_char si_family; u_short si_port; } su_si; struct sockaddr_in su_sin; struct sockaddr_in6 su_sin6; }; #define su_len su_si.si_len #define su_family su_si.si_family #define su_port su_si.si_port void doit(union sockunion *); static void rshd_errx(int, const char *, ...) __printf0like(2, 3); void getstr(char *, int, const char *); int local_domain(char *); char *topdomain(char *); void usage(void); #define OPTIONS "alnDL" int main(int argc, char *argv[]) { extern int __check_rhosts_file; struct linger linger; int ch, on = 1, 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': /* ignored for compatibility */ break; case 'l': __check_rhosts_file = 0; break; case 'n': keepalive = 0; break; #ifdef CRYPT case 'x': doencrypt = 1; break; #endif case 'D': no_delay = 1; break; case 'L': log_success = 1; break; case '?': default: usage(); break; } argc -= optind; argv += optind; #ifdef CRYPT if (doencrypt) { syslog(LOG_ERR, "-k is required for -x"); exit(2); } #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"); if (no_delay && setsockopt(0, IPPROTO_TCP, TCP_NODELAY, &on, sizeof(on)) < 0) syslog(LOG_WARNING, "setsockopt (TCP_NODELAY): %m"); doit((union sockunion *)&from); /* NOTREACHED */ return(0); } #ifdef USE_PAM /* * We can't have a conversation with the client over the rsh connection. * You must use auth methods that don't require one, like pam_rhosts. */ static int null_conv(int num_msg __unused, const struct pam_message **msg __unused, struct pam_response **resp __unused, void *appdata_ptr __unused) { syslog(LOG_ERR, "PAM conversation is not supported"); return PAM_CONV_ERR; } #endif /* USE_PAM */ char username[20] = "USER="; char homedir[64] = "HOME="; char shell[64] = "SHELL="; char path[100] = "PATH="; char *envinit[] = {homedir, shell, path, username, 0}; char **environ; void doit(union sockunion *fromp) { extern char *__rcmd_errstr; /* syslog hook from libc/net/rcmd.c. */ struct passwd *pwd; u_short port; fd_set ready, readfrom; int cc, nfd, pv[2], pid, s; int one = 1; const char *errorstr; char *cp, sig, buf[BUFSIZ]; char cmdbuf[NCARGS+1], locuser[16], remuser[16]; char fromhost[2 * MAXHOSTNAMELEN + 1]; char numericname[INET6_ADDRSTRLEN]; int af = fromp->su_family, error; #ifdef CRYPT int rc; int pv1[2], pv2[2]; #endif login_cap_t *lc; #ifdef USE_PAM static struct pam_conv conv = { null_conv, NULL }; int retcode; #endif /* USE_PAM */ (void) signal(SIGINT, SIG_DFL); (void) signal(SIGQUIT, SIG_DFL); (void) signal(SIGTERM, SIG_DFL); fromp->su_port = ntohs((u_short)fromp->su_port); if (af != AF_INET #ifdef INET6 && af != AF_INET6 #endif ) { syslog(LOG_ERR, "malformed \"from\" address (af %d)", af); exit(1); } error = getnameinfo((struct sockaddr *)fromp, fromp->su_len, numericname, sizeof(numericname), NULL, 0, NI_NUMERICHOST|NI_WITHSCOPEID); /* XXX: do 'error' check */ #ifdef IP_OPTIONS if (af == AF_INET) { u_char optbuf[BUFSIZ/3]; int optsize = sizeof(optbuf), 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 *)optbuf, &optsize) && optsize != 0) { for (i = 0; i < optsize; ) { u_char c = optbuf[i]; if (c == IPOPT_LSRR || c == IPOPT_SSRR) { syslog(LOG_NOTICE, "connection refused from %s with IP option %s", numericname, c == IPOPT_LSRR ? "LSRR" : "SSRR"); exit(1); } if (c == IPOPT_EOL) break; i += (c == IPOPT_NOP) ? 1 : optbuf[i+1]; } } } #endif if (fromp->su_port >= IPPORT_RESERVED || fromp->su_port < IPPORT_RESERVED/2) { syslog(LOG_NOTICE|LOG_AUTH, "connection from %s on illegal port %u", numericname, fromp->su_port); exit(1); } (void) alarm(60); port = 0; s = 0; /* not set or used if 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_af(&lport, af); if (s < 0) { syslog(LOG_ERR, "can't get stderr port: %m"); exit(1); } if (port >= IPPORT_RESERVED || port < IPPORT_RESERVED/2) { syslog(LOG_NOTICE|LOG_AUTH, "2nd socket from %s on unreserved port %u", numericname, port); exit(1); } fromp->su_port = htons(port); if (connect(s, (struct sockaddr *)fromp, fromp->su_len) < 0) { syslog(LOG_INFO, "connect second port %d: %m", port); exit(1); } } errorstr = NULL; realhostname_sa(fromhost, sizeof(fromhost) - 1, (struct sockaddr *)fromp, fromp->su_len); fromhost[sizeof(fromhost) - 1] = '\0'; #ifdef CRYPT if (doencrypt && af == AF_INET) { struct sockaddr_in local_addr; rc = sizeof(local_addr); if (getsockname(0, (struct sockaddr *)&local_addr, &rc) < 0) { syslog(LOG_ERR, "getsockname: %m"); rshd_errx(1, "rlogind: getsockname: %m"); /* XXX */ } authopts = KOPT_DO_MUTUAL; rc = krb_recvauth(authopts, 0, ticket, "rcmd", instance, &fromaddr, &local_addr, kdata, "", schedule, version); des_set_key(&kdata->session, schedule); } #endif getstr(remuser, sizeof(remuser), "remuser"); getstr(locuser, sizeof(locuser), "locuser"); getstr(cmdbuf, sizeof(cmdbuf), "command"); #ifdef USE_PAM retcode = pam_start("rsh", locuser, &conv, &pamh); if (retcode != PAM_SUCCESS) { syslog(LOG_ERR|LOG_AUTH, "pam_start: %s", pam_strerror(pamh, retcode)); rshd_errx(1, "Login incorrect."); } retcode = pam_set_item (pamh, PAM_RUSER, remuser); if (retcode != PAM_SUCCESS) { syslog(LOG_ERR|LOG_AUTH, "pam_set_item(PAM_RUSER): %s", pam_strerror(pamh, retcode)); rshd_errx(1, "Login incorrect."); } retcode = pam_set_item (pamh, PAM_RHOST, fromhost); if (retcode != PAM_SUCCESS) { syslog(LOG_ERR|LOG_AUTH, "pam_set_item(PAM_RHOST): %s", pam_strerror(pamh, retcode)); rshd_errx(1, "Login incorrect."); } retcode = pam_set_item (pamh, PAM_TTY, "tty"); if (retcode != PAM_SUCCESS) { syslog(LOG_ERR|LOG_AUTH, "pam_set_item(PAM_TTY): %s", pam_strerror(pamh, retcode)); rshd_errx(1, "Login incorrect."); } retcode = pam_authenticate(pamh, 0); if (retcode == PAM_SUCCESS) { if ((retcode = pam_get_item(pamh, PAM_USER, (const void **) &cp)) == PAM_SUCCESS) { strncpy(locuser, cp, sizeof(locuser)); locuser[sizeof(locuser) - 1] = '\0'; } else syslog(LOG_ERR|LOG_AUTH, "pam_get_item(PAM_USER): %s", pam_strerror(pamh, retcode)); retcode = pam_acct_mgmt(pamh, 0); } if (retcode != PAM_SUCCESS) { syslog(LOG_INFO|LOG_AUTH, "%s@%s as %s: permission denied (%s). cmd='%.80s'", remuser, fromhost, locuser, pam_strerror(pamh, retcode), cmdbuf); rshd_errx(1, "Login incorrect."); } #endif /* USE_PAM */ setpwent(); pwd = getpwnam(locuser); if (pwd == NULL) { syslog(LOG_INFO|LOG_AUTH, "%s@%s as %s: unknown login. cmd='%.80s'", remuser, fromhost, locuser, cmdbuf); if (errorstr == NULL) errorstr = "Login incorrect."; rshd_errx(1, errorstr, fromhost); } #ifndef USE_PAM if (errorstr || (pwd->pw_expire && time(NULL) >= pwd->pw_expire) || iruserok_sa(fromp, fromp->su_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, fromhost, locuser, __rcmd_errstr, cmdbuf); else syslog(LOG_INFO|LOG_AUTH, "%s@%s as %s: permission denied. cmd='%.80s'", remuser, fromhost, locuser, cmdbuf); if (errorstr == NULL) errorstr = "Login incorrect."; rshd_errx(1, errorstr, fromhost); } #endif /* USE_PAM */ lc = login_getpwclass(pwd); if (pwd->pw_uid) auth_checknologin(lc); if (chdir(pwd->pw_dir) < 0) { if (chdir("/") < 0 || login_getcapbool(lc, "requirehome", !!pwd->pw_uid)) { syslog(LOG_INFO|LOG_AUTH, "%s@%s as %s: no home directory. cmd='%.80s'", remuser, fromhost, locuser, cmdbuf); rshd_errx(0, "No remote home directory."); } pwd->pw_dir = "/"; } if (lc != NULL && fromp->su_family == AF_INET) { /*XXX*/ char remote_ip[MAXHOSTNAMELEN]; strncpy(remote_ip, numericname, sizeof(remote_ip) - 1); remote_ip[sizeof(remote_ip) - 1] = 0; if (!auth_hostok(lc, fromhost, remote_ip)) { syslog(LOG_INFO|LOG_AUTH, "%s@%s as %s: permission denied (%s). cmd='%.80s'", remuser, fromhost, locuser, __rcmd_errstr, cmdbuf); rshd_errx(1, "Login incorrect."); } if (!auth_timeok(lc, time(NULL))) rshd_errx(1, "Logins not available right now"); } #if BSD > 43 /* before fork, while we're session leader */ if (setlogin(pwd->pw_name) < 0) syslog(LOG_ERR, "setlogin() failed: %m"); #endif /* * PAM modules might add supplementary groups in * pam_setcred(), so initialize them first. * But we need to open the session as root. */ if (setusercontext(lc, pwd, pwd->pw_uid, LOGIN_SETGROUP) != 0) { syslog(LOG_ERR, "setusercontext: %m"); exit(1); } #ifdef USE_PAM if ((retcode = pam_open_session(pamh, 0)) != PAM_SUCCESS) { syslog(LOG_ERR, "pam_open_session: %s", pam_strerror(pamh, retcode)); } else if ((retcode = pam_setcred(pamh, PAM_ESTABLISH_CRED)) != PAM_SUCCESS) { syslog(LOG_ERR, "pam_setcred: %s", pam_strerror(pamh, retcode)); } #endif /* USE_PAM */ (void) write(STDERR_FILENO, "\0", 1); sent_null = 1; if (port) { if (pipe(pv) < 0) rshd_errx(1, "Can't make pipe."); #ifdef CRYPT if (doencrypt) { if (pipe(pv1) < 0) rshd_errx(1, "Can't make 2nd pipe."); if (pipe(pv2) < 0) rshd_errx(1, "Can't make 3rd pipe."); } #endif pid = fork(); if (pid == -1) rshd_errx(1, "Can't fork; try again."); if (pid) { #ifdef CRYPT if (doencrypt) { static char msg[] = SECURE_MESSAGE; (void) close(pv1[1]); (void) close(pv2[1]); des_enc_write(s, msg, sizeof(msg) - 1, schedule, &kdata->session); } else #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 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 ioctl(pv[0], FIONBIO, (char *)&one); /* should set s nbio! */ nfd++; do { ready = readfrom; #ifdef CRYPT if (doencrypt) { wready = writeto; if (select(nfd, &ready, &wready, (fd_set *) 0, (struct timeval *) 0) < 0) break; } else #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 if (doencrypt) ret = des_enc_read(s, &sig, 1, schedule, &kdata->session); else #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 if (doencrypt) (void) des_enc_write(s, buf, cc, schedule, &kdata->session); else #endif (void) write(s, buf, cc); } } #ifdef CRYPT 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_enc_write(STDOUT_FILENO, buf, cc, schedule, &kdata->session); } if (doencrypt && FD_ISSET(pv2[0], &wready)) { errno = 0; cc = des_enc_read(STDIN_FILENO, buf, sizeof(buf), schedule, &kdata->session); if (cc <= 0) { shutdown(pv2[0], 1+1); FD_CLR(pv2[0], &writeto); } else (void) write(pv2[0], buf, cc); } #endif } while (FD_ISSET(s, &readfrom) || #ifdef CRYPT (doencrypt && FD_ISSET(pv1[0], &readfrom)) || #endif FD_ISSET(pv[0], &readfrom)); #ifdef USE_PAM PAM_END; #endif /* USE_PAM */ exit(0); } setpgrp(0, getpid()); (void) close(s); (void) close(pv[0]); #ifdef CRYPT if (doencrypt) { close(pv1[0]); close(pv2[0]); dup2(pv1[1], 1); dup2(pv2[1], 0); close(pv1[1]); close(pv2[1]); } #endif dup2(pv[1], 2); close(pv[1]); } #ifdef USE_PAM else { pid = fork(); if (pid == -1) rshd_errx(1, "Can't fork; try again."); if (pid) { /* Parent. */ wait(NULL); PAM_END; exit(0); } } #endif /* USE_PAM */ if (*pwd->pw_shell == '\0') pwd->pw_shell = _PATH_BSHELL; environ = envinit; #ifdef USE_PAM /* * Add any environmental variables that the * PAM modules may have set. */ environ_pam = pam_getenvlist(pamh); if (environ_pam) export_pam_environment(); if ((retcode = pam_end(pamh, 0)) != PAM_SUCCESS) syslog(LOG_ERR|LOG_AUTH, "pam_end: %s", pam_strerror(pamh, retcode)); #endif /* USE_PAM */ strncat(homedir, pwd->pw_dir, sizeof(homedir)-6); strcat(path, _PATH_DEFPATH); strncat(shell, pwd->pw_shell, sizeof(shell)-7); strncat(username, pwd->pw_name, sizeof(username)-6); cp = strrchr(pwd->pw_shell, '/'); if (cp) cp++; else cp = pwd->pw_shell; if (setusercontext(lc, pwd, pwd->pw_uid, LOGIN_SETALL & ~LOGIN_SETGROUP) != 0) { syslog(LOG_ERR, "setusercontext: %m"); exit(1); } login_close(lc); endpwent(); if (log_success || pwd->pw_uid == 0) { syslog(LOG_INFO|LOG_AUTH, "%s@%s as %s: cmd='%.80s'", remuser, fromhost, locuser, cmdbuf); } execl(pwd->pw_shell, cp, "-c", cmdbuf, (char *)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. */ static void rshd_errx(int errcode, const char *fmt, ...) { va_list ap; va_start(ap, fmt); if (sent_null == 0) write(STDERR_FILENO, "\1", 1); verrx(errcode, fmt, ap); /* NOTREACHED */ } void getstr(char *buf, int cnt, const char *error) { char c; do { if (read(STDIN_FILENO, &c, 1) != 1) exit(1); *buf++ = c; if (--cnt == 0) rshd_errx(1, "%s too long", error); } 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) - 1); localhost[sizeof(localhost) - 1] = '\0'; 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); } #ifdef USE_PAM static int export_pam_environment(void) { char **pp; for (pp = environ_pam; *pp != NULL; pp++) { if (ok_to_export(*pp)) (void) putenv(*pp); free(*pp); } return PAM_SUCCESS; } /* * Sanity checks on PAM environmental variables: * - Make sure there is an '=' in the string. * - Make sure the string doesn't run on too long. * - Do not export certain variables. This list was taken from the * Solaris pam_putenv(3) man page. */ static int ok_to_export(const char *s) { static const char *noexport[] = { "SHELL", "HOME", "LOGNAME", "MAIL", "CDPATH", "IFS", "PATH", NULL }; const char **pp; size_t n; if (strlen(s) > 1024 || strchr(s, '=') == NULL) return 0; if (strncmp(s, "LD_", 3) == 0) return 0; for (pp = noexport; *pp != NULL; pp++) { n = strlen(*pp); if (s[n] == '=' && strncmp(s, *pp, n) == 0) return 0; } return 1; } #endif /* USE_PAM */ void usage(void) { syslog(LOG_ERR, "usage: rshd [-%s]", OPTIONS); exit(2); }