#include <u.h>#include <libc.h>#include <ip.h>#include <auth.h> void newchannel(int, char *, int);char *get_string(char *, char *);char *confine(char *, char *);void runcmd(int, int, char *, char *, char *, char *); int errfd, slfd, toppid, sflag, tflag, prevent;char *shell;char *restdir;char *srvpt;char *nsfile = nil;char *uname; voidusage(void){	fprint(2, "usage: sshsession [-s shell] [-r restdir] [-R restdir] [-S srvpt] [-n namespace] [-t]\n");	exits("usage");} main(int argc, char *argv[]){	char *netdir, *filnam, *p, *q;	int ctlfd, fd, n;	char buf[128]; 	rfork(RFNOTEG);	toppid = getpid();	errfd = create("/tmp/ssh.err", OWRITE, 0664);	slfd = open("/dev/syslog", OWRITE);	shell = "/bin/rc -il";	ARGBEGIN {	case 'n':		nsfile = EARGF(usage());		break;	case 'R':		prevent = 1;	case 'r':		restdir = EARGF(usage());		break;	case 's':		sflag = 1;		shell = EARGF(usage());		break;	case 't':		tflag = 1;		break;	case 'S':		srvpt = EARGF(usage());		break;	default:		usage();		break;	} ARGEND; 	uname = getenv("user");	if (uname == nil)		uname = "none";	netdir = getenv("net");	fprint(errfd, "net is %s\n", netdir);	filnam = smprint("%s/clone", netdir);	ctlfd = open(filnam, ORDWR);	if (ctlfd < 0) {		fprint(errfd, "could not clone: %s: %r\n", filnam);		exits(nil);	}	free(filnam);	filnam = smprint("%s/data", netdir);	fd = open(filnam, OREAD);	if (fd < 0) {		fprint(errfd, "Couldn't open data: %r\n");		fprint(ctlfd, "hangup");		exits(nil);	}	n = read(fd, buf, 128);	close(fd);	free(filnam);	if (n < 0) {		fprint(errfd, "Read error for cap: %r\n");		fprint(ctlfd, "hangup");		exits(nil);	}	else if (n > 0) {		buf[n] = '\0';		if (strcmp(buf, "n/a") != 0) {			fd = open("#¤/capuse", OWRITE);			if (fd < 0) {				fprint(errfd, "Couldn't open capuse: %r\n");				fprint(ctlfd, "hangup");				exits(nil);			}			if (write(fd, buf, n) < 0) {				fprint(errfd, "Write to capuse failed: %r\n");				fprint(ctlfd, "hangup");				exits(nil);			}			close(fd);			p = strchr(buf, '@');			if (p) {				++p;				q = strchr(p, '@');				if (q) {					*q = '\0';					uname = strdup(p);				}				if (!tflag) {					if (newns(p, nsfile) < 0)						fprint(errfd, "newns failed: %r\n");				}			}		}	}	n = read(ctlfd, buf, 128);	buf[n] = '\0';	fprint(ctlfd, "announce session");	filnam = smprint("%s/%s/listen", netdir, buf);	fprint(errfd, "listen is %s\n", filnam);	if (access(netdir, AEXIST) < 0) {		p = smprint("/srv/%s", srvpt ? srvpt : "sshtun");		fd = open(p, ORDWR);		if (fd < 0) {			fprint(errfd, "srv open failed; %r\n");			fprint(ctlfd, "hangup");			exits(nil);		}		mount(fd, -1, "/net", MBEFORE, "");	}	while (1) {		fd = open(filnam, ORDWR);		if (fd < 0) {			fprint(errfd, "listen failed: %r\n");			fprint(ctlfd, "hangup");			exits(nil);		}		n = read(fd, buf, 128);		fprint(errfd, "read from listen file returned %d\n", n);		if (n <= 0) {			fprint(errfd, "read on listen failed: %r\n");			fprint(ctlfd, "hangup");			exits(nil);		}		buf[n] = '\0';		fprint(errfd, "read %s\n", buf);		switch (fork()) {		case 0:			close(ctlfd);			newchannel(fd, netdir, atoi(buf));			break;		case -1:			fprint(errfd, "fork failed: %r\n");			fprint(ctlfd, "hangup");			exits(nil);			break;		default:			close(fd);			break;		}	}} voidnewchannel(int fd, char *conndir, int channum){	char *p, *q, *reqfile, *datafile;	int n, reqfd, datafd, motdfd, want_reply, already_done;	char buf[32768], buf2[10240], cmd[1024]; 	close(fd);	already_done = 0;	reqfile = smprint("%s/%d/request", conndir, channum);	reqfd = open(reqfile, ORDWR);	if (reqfd < 0) {		fprint(errfd, "Couldn't open request file: %r\n");		exits(nil);	}	datafile = smprint("%s/%d/data", conndir, channum);	datafd = open(datafile, ORDWR);	if (datafd < 0) {		fprint(errfd, "Couldn't open data file: %r\n");		exits(nil);	}	while (1) {		n = read(reqfd, buf, 32768);		fprint(errfd, "read from request file returned %d\n", n);		if (n == 0) {			exits(nil);		}		else if (n < 0) {			fprint(errfd, "Read failed: %r\n");			exits(nil);		}		for (p = buf; p < buf + n && *p != ' '; ++p) ;		*p = '\0';		++p;		want_reply = (*p == 't');		if (strcmp(buf, "pty-req") == 0) {			if (want_reply)				fprint(reqfd, "success");		}		else if (strcmp(buf, "x11-req") == 0) {			if (want_reply)				fprint(reqfd, "failure");		}		else if (strcmp(buf, "env") == 0) {			if (want_reply)				fprint(reqfd, "failure");		}		else if (strcmp(buf, "shell") == 0) {			if (already_done) {				if (want_reply)					fprint(reqfd, "failure");				continue;			}			switch (fork()) {			case 0:				if (sflag)					snprint(cmd, 1024, "-s%s", shell);				else					snprint(cmd, 1024, "");				if (slfd > 0)					fprint(slfd, "starting ssh shell for %s\n", uname);				else					syslog(1, "ssh", "starting ssh shell for %s", uname);				motdfd = open("/sys/lib/motd", OREAD);				if (motdfd >= 0) {					while ((n = read(motdfd, buf, 8192)) > 0) {						p = buf2;						for (q = buf; q < buf+n; ++q) {							if (*q == '\n')								*p++ = '\r';							*p++ = *q;						}						write(datafd, buf2, p-buf2);					}					close(motdfd);				}//				runcmd(reqfd, datafd, "con", "/bin/conssim", cmd, nil);				runcmd(reqfd, datafd, "con", "/bin/ip/telnetd", "-nt", nil);				exits(nil);			case -1:				if (want_reply)					fprint(reqfd, "failure");				fprint(2, "Cannot fork: %r\n");				exits(nil);				break;			default:				already_done = 1;				if (want_reply)					fprint(reqfd, "success");				break;			}		}		else if (strcmp(buf, "exec") == 0) {			if (already_done) {				if (want_reply)					fprint(reqfd, "failure");				continue;			}			switch (fork()) {			case 0:				if (restdir)					chdir(restdir);				if (!prevent || (q = getenv("sshsession")) && strcmp(q, "allow") == 0)					get_string(p+1, cmd);				else					confine(p+1, cmd);				if (slfd > 0)					fprint(slfd, "running %s for %s\n", cmd, uname);				else					syslog(1, "ssh", "running %s for %s", cmd, uname);				runcmd(reqfd, datafd, "rx", "/bin/rc", "-lc", cmd);				exits(nil);			case -1:				if (want_reply)					fprint(reqfd, "failure");				fprint(errfd, "Cannot fork: %r\n");				exits(nil);				break;			default:				already_done = 1;				if (want_reply)					fprint(reqfd, "success");				break;			}		}		else if (strcmp(buf, "subsystem") == 0) {			if (want_reply)				fprint(reqfd, "failure");		}		else if (strcmp(buf, "window-change") == 0) {			if (want_reply)				fprint(reqfd, "success");		}		else if (strcmp(buf, "xon-xoff") == 0) {		}		else if (strcmp(buf, "signal") == 0) {		}		else if (strcmp(buf, "exit-status") == 0) {		}		else if (strcmp(buf, "exit-signal") == 0) {		}		else			fprint(errfd, "Unknown channel request: %s\n", buf);		}} char *get_string(char *q, char *s){	int n; 	n = nhgetl(q);	q += 4;	memmove(s, q, n);	s[n] = '\0';	q += n;	return q;} char *confine(char *q, char *s){	int i, n, m;	char *p, *e, *r, *buf, *toks[32]; 	n = nhgetl(q);	q += 4;	buf = malloc(n+1);	memmove(buf, q, n);	buf[n]  = 0;	m = tokenize(buf, toks, 32);	e = s + n + 1;	for (i = 0, r = s; i < m; ++i) {		p = strrchr(toks[i], '/');		if (p) {			if (*(p+1))				r = seprint(r, e, "%s ", p+1);			else				r = seprint(r, e, ". ");		}		else			r = seprint(r, e, "%s ", toks[i]);	}	free(buf);	q += n;	return q;} voidruncmd(int reqfd, int datafd, char *svc, char *cmd, char *arg1, char *arg2){	char *p;	int fd, cmdpid, child; 	cmdpid = rfork(RFPROC|RFMEM|RFNOTEG|RFFDG);	switch (cmdpid) {	case -1:		fprint(errfd, "fork failed: %r\n");		break;	case 0:		if (restdir == nil) {			p = smprint("/usr/%s", uname);			if (access(p, AREAD) == 0)				chdir(p);			free(p);		}		p = strrchr(cmd, '/');		if (p)			++p;		else			p = cmd;		dup(datafd, 0);		dup(datafd, 1);		dup(datafd, 2);		close(datafd);		putenv("service", svc);		fprint(errfd, "starting %s\n", cmd);		execl(cmd, p, arg1, arg2, nil);		fprint(errfd, "cannot exec %s: %r\n", cmd);		break;	default:		close(datafd);		while (1) {			fprint(errfd, "waiting for child %d\n", cmdpid);			child = waitpid();			fprint(errfd, "child %d passed\n", child);			if (child == cmdpid || child == -1)				break;		}		if (child == -1)			fprint(errfd, "wait failed: %r\n");		if (slfd > 0)			fprint(slfd, "closing ssh session for %s\n", uname);		else			syslog(1, "ssh", "closing ssh session for %s", uname);		fprint(errfd, "closing connection\n");		write(reqfd, "close", 5);		p = smprint("/proc/%d/notepg", toppid);		fd = open(p, OWRITE);		write(fd, "interrupt", 3);		close(fd);		break;	}	exits(nil);}