/*- * Copyright (c) 1988, 1989, 1992, 1993, 1994 * The Regents of the University of California. All rights reserved. * Copyright (c) 2002 Networks Associates Technology, Inc. * All rights reserved. * * Portions of this software were developed for the FreeBSD Project by * ThinkSec AS and NAI Labs, the Security Research Division of Network * Associates, Inc. under DARPA/SPAWAR contract N66001-01-C-8035 * ("CBOSS"), as part of the DARPA CHATS research program. * * 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. */ #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 #endif /* not lint */ #include <sys/cdefs.h> __FBSDID("$FreeBSD$"); /* * remote shell server: * [port]\0 * ruser\0 * luser\0 * command\0 * data */ #include <sys/param.h> #include <sys/ioctl.h> #include <sys/time.h> #include <sys/socket.h> #include <netinet/in_systm.h> #include <netinet/in.h> #include <netinet/ip.h> #include <netinet/tcp.h> #include <arpa/inet.h> #include <netdb.h> #include <err.h> #include <errno.h> #include <fcntl.h> #include <libutil.h> #include <paths.h> #include <pwd.h> #include <signal.h> #include <stdarg.h> #include <stdio.h> #include <stdlib.h> #include <string.h> #include <syslog.h> #include <unistd.h> #include <login_cap.h> #include <security/pam_appl.h> #include <security/openpam.h> #include <sys/wait.h> #ifdef USE_BLACKLIST #include <blacklist.h> #endif static struct pam_conv pamc = { openpam_nullconv, NULL }; static pam_handle_t *pamh; static int pam_err; #define PAM_END { \ if ((pam_err = pam_setcred(pamh, PAM_DELETE_CRED)) != PAM_SUCCESS) \ syslog(LOG_ERR|LOG_AUTH, "pam_setcred(): %s", pam_strerror(pamh, pam_err)); \ if ((pam_err = pam_close_session(pamh,0)) != PAM_SUCCESS) \ syslog(LOG_ERR|LOG_AUTH, "pam_close_session(): %s", pam_strerror(pamh, pam_err)); \ if ((pam_err = pam_end(pamh, pam_err)) != PAM_SUCCESS) \ syslog(LOG_ERR|LOG_AUTH, "pam_end(): %s", pam_strerror(pamh, pam_err)); \ } int keepalive = 1; int log_success; /* If TRUE, log all successful accesses */ int sent_null; int no_delay; void doit(struct sockaddr *); 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); char slash[] = "/"; char bshell[] = _PATH_BSHELL; #define OPTIONS "aDLln" int main(int argc, char *argv[]) { extern int __check_rhosts_file; struct linger linger; socklen_t fromlen; int ch, on = 1; struct sockaddr_storage from; openlog("rshd", LOG_PID, 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; case 'D': no_delay = 1; break; case 'L': log_success = 1; break; case '?': default: usage(); break; } argc -= optind; argv += optind; 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((struct sockaddr *)&from); /* NOTREACHED */ return(0); } extern char **environ; void doit(struct sockaddr *fromp) { extern char *__rcmd_errstr; /* syslog hook from libc/net/rcmd.c. */ struct passwd *pwd; u_short port; fd_set ready, readfrom; int cc, fd, nfd, pv[2], pid, s; int one = 1; const char *cp, *errorstr; char sig, buf[BUFSIZ]; char *cmdbuf, luser[16], ruser[16]; char rhost[2 * MAXHOSTNAMELEN + 1]; char numericname[INET6_ADDRSTRLEN]; int af, srcport; int maxcmdlen; login_cap_t *lc; maxcmdlen = (int)sysconf(_SC_ARG_MAX); if (maxcmdlen <= 0 || (cmdbuf = malloc(maxcmdlen)) == NULL) exit(1); (void) signal(SIGINT, SIG_DFL); (void) signal(SIGQUIT, SIG_DFL); (void) signal(SIGTERM, SIG_DFL); af = fromp->sa_family; srcport = ntohs(*((in_port_t *)&fromp->sa_data)); if (af == AF_INET) { inet_ntop(af, &((struct sockaddr_in *)fromp)->sin_addr, numericname, sizeof numericname); } else if (af == AF_INET6) { inet_ntop(af, &((struct sockaddr_in6 *)fromp)->sin6_addr, numericname, sizeof numericname); } else { syslog(LOG_ERR, "malformed \"from\" address (af %d)", af); exit(1); } #ifdef IP_OPTIONS if (af == AF_INET) { u_char optbuf[BUFSIZ/3]; socklen_t 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, 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 (srcport >= IPPORT_RESERVED || srcport < IPPORT_RESERVED/2) { syslog(LOG_NOTICE|LOG_AUTH, "connection from %s on illegal port %u", numericname, srcport); #ifdef USE_BLACKLIST blacklist(1, STDIN_FILENO, "illegal port"); #endif 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, 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 || port < IPPORT_RESERVED/2) { syslog(LOG_NOTICE|LOG_AUTH, "2nd socket from %s on unreserved port %u", numericname, port); #ifdef USE_BLACKLIST blacklist(1, STDIN_FILENO, "unreserved port"); #endif exit(1); } *((in_port_t *)&fromp->sa_data) = htons(port); if (connect(s, fromp, fromp->sa_len) < 0) { syslog(LOG_INFO, "connect second port %d: %m", port); exit(1); } } errorstr = NULL; realhostname_sa(rhost, sizeof(rhost) - 1, fromp, fromp->sa_len); rhost[sizeof(rhost) - 1] = '\0'; /* XXX truncation! */ (void) alarm(60); getstr(ruser, sizeof(ruser), "ruser"); getstr(luser, sizeof(luser), "luser"); getstr(cmdbuf, maxcmdlen, "command"); (void) alarm(0); pam_err = pam_start("rsh", luser, &pamc, &pamh); if (pam_err != PAM_SUCCESS) { syslog(LOG_ERR|LOG_AUTH, "pam_start(): %s", pam_strerror(pamh, pam_err)); #ifdef USE_BLACKLIST blacklist(1, STDIN_FILENO, "login incorrect"); #endif rshd_errx(1, "Login incorrect."); } if ((pam_err = pam_set_item(pamh, PAM_RUSER, ruser)) != PAM_SUCCESS || (pam_err = pam_set_item(pamh, PAM_RHOST, rhost)) != PAM_SUCCESS) { syslog(LOG_ERR|LOG_AUTH, "pam_set_item(): %s", pam_strerror(pamh, pam_err)); #ifdef USE_BLACKLIST blacklist(1, STDIN_FILENO, "login incorrect"); #endif rshd_errx(1, "Login incorrect."); } pam_err = pam_authenticate(pamh, 0); if (pam_err == PAM_SUCCESS) { if ((pam_err = pam_get_user(pamh, &cp, NULL)) == PAM_SUCCESS) { strncpy(luser, cp, sizeof(luser)); luser[sizeof(luser) - 1] = '\0'; /* XXX truncation! */ } pam_err = pam_acct_mgmt(pamh, 0); } if (pam_err != PAM_SUCCESS) { syslog(LOG_INFO|LOG_AUTH, "%s@%s as %s: permission denied (%s). cmd='%.80s'", ruser, rhost, luser, pam_strerror(pamh, pam_err), cmdbuf); #ifdef USE_BLACKLIST blacklist(1, STDIN_FILENO, "permission denied"); #endif rshd_errx(1, "Login incorrect."); } setpwent(); pwd = getpwnam(luser); if (pwd == NULL) { syslog(LOG_INFO|LOG_AUTH, "%s@%s as %s: unknown login. cmd='%.80s'", ruser, rhost, luser, cmdbuf); #ifdef USE_BLACKLIST blacklist(1, STDIN_FILENO, "unknown login"); #endif if (errorstr == NULL) errorstr = "Login incorrect."; rshd_errx(1, errorstr, rhost); } 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'", ruser, rhost, luser, cmdbuf); rshd_errx(0, "No remote home directory."); } pwd->pw_dir = slash; } if (lc != NULL && fromp->sa_family == AF_INET) { /*XXX*/ char remote_ip[MAXHOSTNAMELEN]; strncpy(remote_ip, numericname, sizeof(remote_ip) - 1); remote_ip[sizeof(remote_ip) - 1] = 0; /* XXX truncation! */ if (!auth_hostok(lc, rhost, remote_ip)) { syslog(LOG_INFO|LOG_AUTH, "%s@%s as %s: permission denied (%s). cmd='%.80s'", ruser, rhost, luser, __rcmd_errstr, cmdbuf); #ifdef USE_BLACKLIST blacklist(1, STDIN_FILENO, "permission denied"); #endif rshd_errx(1, "Login incorrect."); } if (!auth_timeok(lc, time(NULL))) rshd_errx(1, "Logins not available right now"); } /* * 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); } if ((pam_err = pam_open_session(pamh, 0)) != PAM_SUCCESS) { syslog(LOG_ERR, "pam_open_session: %s", pam_strerror(pamh, pam_err)); } else if ((pam_err = pam_setcred(pamh, PAM_ESTABLISH_CRED)) != PAM_SUCCESS) { syslog(LOG_ERR, "pam_setcred: %s", pam_strerror(pamh, pam_err)); } (void) write(STDERR_FILENO, "\0", 1); sent_null = 1; if (port) { if (pipe(pv) < 0) rshd_errx(1, "Can't make pipe."); pid = fork(); if (pid == -1) rshd_errx(1, "Can't fork; try again."); if (pid) { (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; ioctl(pv[0], FIONBIO, (char *)&one); /* should set s nbio! */ nfd++; do { ready = readfrom; if (select(nfd, &ready, (fd_set *)0, (fd_set *)0, (struct timeval *)0) < 0) break; if (FD_ISSET(s, &ready)) { int ret; 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, SHUT_RDWR); FD_CLR(pv[0], &readfrom); } else { (void)write(s, buf, cc); } } } while (FD_ISSET(s, &readfrom) || FD_ISSET(pv[0], &readfrom)); PAM_END; exit(0); } (void) close(s); (void) close(pv[0]); dup2(pv[1], 2); close(pv[1]); } else { pid = fork(); if (pid == -1) rshd_errx(1, "Can't fork; try again."); if (pid) { /* Parent. */ while (wait(NULL) > 0 || errno == EINTR) /* nothing */ ; PAM_END; exit(0); } } #ifdef USE_BLACKLIST blacklist(0, STDIN_FILENO, "success"); #endif for (fd = getdtablesize(); fd > 2; fd--) (void) close(fd); if (setsid() == -1) syslog(LOG_ERR, "setsid() failed: %m"); if (setlogin(pwd->pw_name) < 0) syslog(LOG_ERR, "setlogin() failed: %m"); if (*pwd->pw_shell == '\0') pwd->pw_shell = bshell; (void) pam_setenv(pamh, "HOME", pwd->pw_dir, 1); (void) pam_setenv(pamh, "SHELL", pwd->pw_shell, 1); (void) pam_setenv(pamh, "USER", pwd->pw_name, 1); (void) pam_setenv(pamh, "PATH", _PATH_DEFPATH, 1); environ = pam_getenvlist(pamh); (void) pam_end(pamh, pam_err); 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'", ruser, rhost, luser, cmdbuf); } execl(pwd->pw_shell, cp, "-c", cmdbuf, (char *)NULL); err(1, "%s", 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) { #ifdef USE_BLACKLIST blacklist(1, STDIN_FILENO, "buffer overflow"); #endif 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'; /* XXX truncation! */ 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); }