/* $OpenBSD: rsh.c,v 1.38 2005/07/04 01:54:10 djm Exp $ */ /*- * Copyright (c) 1983, 1990 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. */ #ifndef lint static const char copyright[] = "@(#) Copyright (c) 1983, 1990 The Regents of the University of California.\n\ All rights reserved.\n"; #endif /* not lint */ #ifndef lint /*static const char sccsid[] = "from: @(#)rsh.c 5.24 (Berkeley) 7/1/91";*/ static const char rcsid[] = "$OpenBSD: rsh.c,v 1.38 2005/07/04 01:54:10 djm Exp $"; #endif /* not lint */ #include <sys/types.h> #include <sys/socket.h> #include <sys/ioctl.h> #include <sys/file.h> #include <netinet/in.h> #include <err.h> #include <errno.h> #include <netdb.h> #include <poll.h> #include <pwd.h> #include <signal.h> #include <stdarg.h> #include <stdio.h> #include <stdlib.h> #include <string.h> #include <unistd.h> #include "pathnames.h" __dead void usage(void); void sendsig(int); char *copyargs(char **argv); void talk(int, sigset_t *, int, int); /* * rsh - remote shell */ int rfd2; int main(int argc, char *argv[]) { struct passwd *pw; struct servent *sp; sigset_t mask, omask; int argoff = 0, asrsh = 0, ch, dflag = 0, nflag = 0, one = 1, rem; char *args, *host = NULL, *user = NULL; pid_t pid = 0; extern char *__progname; uid_t uid; /* if called as something other than "rsh", use it as the host name */ if (strcmp(__progname, "rsh") != 0) host = __progname; else asrsh = 1; /* handle "rsh host flags" */ if (!host && argc > 2 && argv[1][0] != '-') { host = argv[1]; argoff = 1; } while ((ch = getopt(argc - argoff, argv + argoff, "8KLdel:nw")) != -1) switch(ch) { case '8': /* -8KLew are ignored to allow rlogin aliases */ case 'K': case 'L': case 'e': case 'w': break; case 'd': dflag = 1; break; case 'l': user = optarg; break; case 'n': nflag = 1; break; default: usage(); } optind += argoff; uid = getuid(); /* if haven't gotten a host yet, do so */ if (!host && !(host = argv[optind++])) usage(); /* if no command, login to remote host via ssh. */ if (!argv[optind]) { if (setresuid(uid, uid, uid) == -1) err(1, "setresuid"); if (asrsh) *argv = "ssh"; execv(_PATH_SSH, argv); errx(1, "can't exec %s", _PATH_SSH); } argc -= optind; argv += optind; if (geteuid() != 0) errx(1, "must be setuid root"); if ((pw = getpwuid(uid)) == NULL) errx(1, "unknown user ID %u", uid); if (user == NULL) user = pw->pw_name; args = copyargs(argv); if ((sp = getservbyname("shell", "tcp")) == NULL) errx(1, "shell/tcp: unknown service"); (void)unsetenv("RSH"); /* no tricks with rcmd(3) */ rem = rcmd_af(&host, sp->s_port, pw->pw_name, user, args, &rfd2, PF_UNSPEC); if (rem < 0) exit(1); if (rfd2 < 0) errx(1, "can't establish stderr"); if (setresuid(uid, uid, uid) == -1) err(1, "setresuid"); if (dflag) { if (setsockopt(rem, SOL_SOCKET, SO_DEBUG, &one, sizeof(one)) < 0) warn("setsockopt"); if (setsockopt(rfd2, SOL_SOCKET, SO_DEBUG, &one, sizeof(one)) < 0) warn("setsockopt"); } sigemptyset(&mask); sigaddset(&mask, SIGINT); sigaddset(&mask, SIGQUIT); sigaddset(&mask, SIGTERM); sigprocmask(SIG_BLOCK, &mask, &omask); if (signal(SIGINT, SIG_IGN) != SIG_IGN) (void)signal(SIGINT, sendsig); if (signal(SIGQUIT, SIG_IGN) != SIG_IGN) (void)signal(SIGQUIT, sendsig); if (signal(SIGTERM, SIG_IGN) != SIG_IGN) (void)signal(SIGTERM, sendsig); if (!nflag) { if ((pid = fork()) < 0) err(1, "fork"); } (void)ioctl(rfd2, FIONBIO, &one); (void)ioctl(rem, FIONBIO, &one); talk(nflag, &omask, pid, rem); if (!nflag) (void)kill(pid, SIGKILL); return 0; } void talk(int nflag, sigset_t *omask, pid_t pid, int rem) { int cc, wc; char *bp; struct pollfd pfd[2]; char buf[BUFSIZ]; if (!nflag && pid == 0) { (void)close(rfd2); reread: errno = 0; if ((cc = read(STDIN_FILENO, buf, sizeof buf)) <= 0) goto done; bp = buf; pfd[0].fd = rem; pfd[0].events = POLLOUT; rewrite: if (poll(pfd, 1, INFTIM) < 0) { if (errno != EINTR) err(1, "poll"); goto rewrite; } if (pfd[0].revents & (POLLERR|POLLHUP|POLLNVAL)) err(1, "poll"); wc = write(rem, bp, cc); if (wc < 0) { if (errno == EWOULDBLOCK) goto rewrite; goto done; } bp += wc; cc -= wc; if (cc == 0) goto reread; goto rewrite; done: (void)shutdown(rem, 1); exit(0); } sigprocmask(SIG_SETMASK, omask, NULL); pfd[1].fd = rfd2; pfd[1].events = POLLIN; pfd[0].fd = rem; pfd[0].events = POLLIN; do { if (poll(pfd, 2, INFTIM) < 0) { if (errno != EINTR) err(1, "poll"); continue; } if ((pfd[0].revents & (POLLERR|POLLHUP|POLLNVAL)) || (pfd[1].revents & (POLLERR|POLLHUP|POLLNVAL))) err(1, "poll"); if (pfd[1].revents & POLLIN) { errno = 0; cc = read(rfd2, buf, sizeof buf); if (cc <= 0) { if (errno != EWOULDBLOCK) pfd[1].revents = 0; } else (void)write(STDERR_FILENO, buf, cc); } if (pfd[0].revents & POLLIN) { errno = 0; cc = read(rem, buf, sizeof buf); if (cc <= 0) { if (errno != EWOULDBLOCK) pfd[0].revents = 0; } else (void)write(STDOUT_FILENO, buf, cc); } } while ((pfd[0].revents & POLLIN) || (pfd[1].revents & POLLIN)); } void sendsig(int signo) { int save_errno = errno; (void)write(rfd2, &signo, 1); errno = save_errno; } char * copyargs(char **argv) { char **ap, *p, *args; size_t cc, len; cc = 0; for (ap = argv; *ap; ++ap) cc += strlen(*ap) + 1; if ((args = malloc(cc)) == NULL) err(1, NULL); for (p = args, ap = argv; *ap; ++ap) { len = strlcpy(p, *ap, cc); if (len >= cc) errx(1, "copyargs overflow"); p += len; cc -= len; if (ap[1]) { *p++ = ' '; cc--; } } return(args); } __dead void usage(void) { (void)fprintf(stderr, "usage: rsh [-Kdn] [-l username] hostname [command]\n"); exit(1); }