/* $NetBSD: rshd.c,v 1.32 2003/08/07 09:46:49 agc Exp $ */ /* * Copyright (C) 1998 WIDE Project. * 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 WIDE Project and * its contributors. * 4. Neither the name of the project 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 PROJECT 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 PROJECT 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. */ /*- * 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. */ #include #ifndef lint __COPYRIGHT("@(#) Copyright (c) 1988, 1989, 1992, 1993, 1994\n\ The Regents of the University of California. All rights reserved.\n"); #if 0 static char sccsid[] = "@(#)rshd.c 8.2 (Berkeley) 4/6/94"; #else __RCSID("$NetBSD: rshd.c,v 1.32 2003/08/07 09:46:49 agc Exp $"); #endif #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 #ifdef LOGIN_CAP #include #endif int keepalive = 1; int check_all; int log_success; /* If TRUE, log all successful accesses */ int sent_null; void doit __P((struct sockaddr *)); void error __P((const char *, ...)) __attribute__((__format__(__printf__, 1, 2))); void getstr __P((char *, int, char *)); int local_domain __P((char *)); char *topdomain __P((char *)); void usage __P((void)); int main __P((int, char *[])); #define OPTIONS "alnL" extern int __check_rhosts_file; extern char *__rcmd_errstr; /* syslog hook from libc/net/rcmd.c. */ int main(int argc, char *argv[]) { struct linger linger; int ch, on = 1, fromlen; struct sockaddr_storage from; struct protoent *proto; openlog("rshd", LOG_PID, 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; case 'L': log_success = 1; break; case '?': default: usage(); break; } argc -= optind; argv += optind; fromlen = sizeof (from); /* xxx */ if (getpeername(0, (struct sockaddr *)&from, &fromlen) < 0) { syslog(LOG_ERR, "getpeername: %m"); exit(1); } #if 0 if (((struct sockaddr *)&from)->sa_family == AF_INET6 && IN6_IS_ADDR_V4MAPPED(&((struct sockaddr_in6 *)&from)->sin6_addr) && sizeof(struct sockaddr_in) <= sizeof(from)) { struct sockaddr_in sin; struct sockaddr_in6 *sin6; const int off = sizeof(struct sockaddr_in6) - sizeof(struct sockaddr_in); sin6 = (struct sockaddr_in6 *)&from; memset(&sin, 0, sizeof(sin)); sin.sin_family = AF_INET; sin.sin_len = sizeof(struct sockaddr_in); memcpy(&sin.sin_addr, &sin6->sin6_addr.s6_addr[off], sizeof(sin.sin_addr)); memcpy(&from, &sin, sizeof(sin)); fromlen = sin.sin_len; } #else if (((struct sockaddr *)&from)->sa_family == AF_INET6 && IN6_IS_ADDR_V4MAPPED(&((struct sockaddr_in6 *)&from)->sin6_addr)) { char hbuf[NI_MAXHOST]; if (getnameinfo((struct sockaddr *)&from, fromlen, hbuf, sizeof(hbuf), NULL, 0, NI_NUMERICHOST) != 0) { strlcpy(hbuf, "invalid", sizeof(hbuf)); } syslog(LOG_ERR, "malformed \"from\" address (v4 mapped, %s)", hbuf); exit(1); } #endif 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"); proto = getprotobyname("tcp"); setsockopt(0, proto->p_proto, TCP_NODELAY, &on, sizeof(on)); doit((struct sockaddr *)&from); /* NOTREACHED */ #ifdef __GNUC__ exit(0); #endif } 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(struct sockaddr *fromp) { struct passwd *pwd; in_port_t port; struct pollfd set[2]; int cc, pv[2], pid, s = -1; /* XXX gcc */ int one = 1; char *hostname, *errorstr, *errorhost = NULL; /* XXX gcc */ const char *cp; char sig, buf[BUFSIZ]; char cmdbuf[NCARGS+1], locuser[16], remuser[16]; char remotehost[2 * MAXHOSTNAMELEN + 1]; char hostnamebuf[2 * MAXHOSTNAMELEN + 1]; #ifdef LOGIN_CAP login_cap_t *lc; #endif char naddr[NI_MAXHOST]; char saddr[NI_MAXHOST]; char raddr[NI_MAXHOST]; char pbuf[NI_MAXSERV]; int af = fromp->sa_family; u_int16_t *portp; struct addrinfo hints, *res, *res0; int gaierror; #ifdef NI_WITHSCOPEID const int niflags = NI_NUMERICHOST | NI_NUMERICSERV | NI_WITHSCOPEID; #else const int niflags = NI_NUMERICHOST | NI_NUMERICSERV; #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 (af) { case AF_INET: portp = &((struct sockaddr_in *)fromp)->sin_port; break; #ifdef INET6 case AF_INET6: portp = &((struct sockaddr_in6 *)fromp)->sin6_port; break; #endif default: syslog(LOG_ERR, "malformed \"from\" address (af %d)", af); exit(1); } if (getnameinfo(fromp, fromp->sa_len, naddr, sizeof(naddr), pbuf, sizeof(pbuf), niflags) != 0) { syslog(LOG_ERR, "malformed \"from\" address (af %d)", af); exit(1); } #ifdef IP_OPTIONS if (af == AF_INET) { u_char optbuf[BUFSIZ/3], *cp; char lbuf[BUFSIZ], *lp, *ep; int optsize = sizeof(optbuf), ipproto; 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) { lp = lbuf; ep = lbuf + sizeof(lbuf); for (cp = optbuf; optsize > 0; cp++, optsize--, lp += 3) snprintf(lp, ep - lp, " %2.2x", *cp); syslog(LOG_NOTICE, "Connection received from %s using IP options (ignored):%s", naddr, lbuf); if (setsockopt(0, ipproto, IP_OPTIONS, (char *)NULL, optsize) != 0) { syslog(LOG_ERR, "setsockopt IP_OPTIONS NULL: %m"); exit(1); } } } #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_ERR, "read: %m"); shutdown(0, SHUT_RDWR); 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) { syslog(LOG_ERR, "2nd port not reserved"); exit(1); } *portp = htons(port); if (connect(s, (struct sockaddr *)fromp, fromp->sa_len) < 0) { syslog(LOG_ERR, "connect second port %d: %m", port); exit(1); } } #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; 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_NOTICE, "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; } 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 = "Permission denied.\n"; goto fail; } #ifdef LOGIN_CAP lc = login_getclass(pwd ? pwd->pw_class : NULL); #endif if (chdir(pwd->pw_dir) < 0) { #ifdef LOGIN_CAP if (chdir("/") < 0 || login_getcapbool(lc, "requirehome", pwd->pw_uid ? 1 : 0)) { syslog(LOG_INFO|LOG_AUTH, "%s@%s as %s: no home directory. cmd='%.80s'", remuser, hostname, locuser, cmdbuf); error("No remote home directory.\n"); exit(0); } #else (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 /* notdef */ #endif /* LOGIN_CAP */ } 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 && !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); } pid = fork(); if (pid == -1) { error("Can't fork; try again.\n"); exit(1); } if (pid) { { (void) close(0); (void) close(1); } (void) close(2); (void) close(pv[1]); set[0].fd = s; set[0].events = POLLIN; set[1].fd = pv[0]; set[1].events = POLLIN; ioctl(pv[0], FIONBIO, (char *)&one); /* should set s nbio! */ do { if (poll(set, 2, INFTIM) < 0) break; if (set[0].revents & POLLIN) { int ret; ret = read(s, &sig, 1); if (ret <= 0) set[0].events = 0; else killpg(pid, sig); } if (set[1].revents & POLLIN) { errno = 0; cc = read(pv[0], buf, sizeof(buf)); if (cc <= 0) { shutdown(s, SHUT_RDWR); set[1].events = 0; } else { (void) write(s, buf, cc); } } } while ((set[0].revents | set[1].revents) & POLLIN); exit(0); } (void) close(s); (void) close(pv[0]); dup2(pv[1], 2); close(pv[1]); } setsid(); if (*pwd->pw_shell == '\0') pwd->pw_shell = _PATH_BSHELL; #ifdef LOGIN_CAP { char *sh; if((sh = login_getcapstr(lc, "shell", NULL, NULL))) { if(!(sh = strdup(sh))) { syslog(LOG_ERR, "Cannot alloc mem"); exit(1); } pwd->pw_shell = sh; } } #endif environ = envinit; strlcat(homedir, pwd->pw_dir, sizeof(homedir)); strlcat(path, _PATH_DEFPATH, sizeof(path)); strlcat(shell, pwd->pw_shell, sizeof(shell)); strlcat(username, pwd->pw_name, sizeof(username)); #ifdef LOGIN_CAP if (setusercontext(lc, pwd, pwd->pw_uid, LOGIN_SETALL) != 0) { syslog(LOG_ERR, "setusercontext: %m"); exit(1); } login_close(lc); #else (void) setgid((gid_t)pwd->pw_gid); initgroups(pwd->pw_name, pwd->pw_gid); (void) setuid((uid_t)pwd->pw_uid); #endif endpwent(); if (log_success || pwd->pw_uid == 0) { syslog(LOG_INFO|LOG_AUTH, "%s@%s as %s: cmd='%.80s'", remuser, hostname, locuser, cmdbuf); } cp = strrchr(pwd->pw_shell, '/'); if (cp) cp++; else cp = pwd->pw_shell; execl(pwd->pw_shell, cp, "-c", cmdbuf, 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. */ #include 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) - 1, 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 + 1]; char *p1, *p2; localhost[0] = 0; (void)gethostname(localhost, sizeof(localhost)); 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); } void usage(void) { syslog(LOG_ERR, "usage: rshd [-%s]", OPTIONS); exit(2); }