xref: /dragonfly/crypto/openssh/sshpty.c (revision 1de703da) 
1 /*
2  * Author: Tatu Ylonen <ylo@cs.hut.fi>
3  * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
4  *                    All rights reserved
5  * Allocating a pseudo-terminal, and making it the controlling tty.
6  *
7  * As far as I am concerned, the code I have written for this software
8  * can be used freely for any purpose.  Any derived versions of this
9  * software must be clearly marked as such, and if the derived work is
10  * incompatible with the protocol description in the RFC file, it must be
11  * called by a name other than "ssh" or "Secure Shell".
12  */
13 
14 #include "includes.h"
15 RCSID("$OpenBSD: sshpty.c,v 1.7 2002/06/24 17:57:20 deraadt Exp $");
16 RCSID("$FreeBSD: src/crypto/openssh/sshpty.c,v 1.2.2.3 2003/02/03 17:31:08 des Exp $");
17 RCSID("$DragonFly: src/crypto/openssh/Attic/sshpty.c,v 1.2 2003/06/17 04:24:36 dillon Exp $");
18 
19 #ifdef HAVE_UTIL_H
20 # include <util.h>
21 #endif /* HAVE_UTIL_H */
22 
23 #include "sshpty.h"
24 #include "log.h"
25 #include "misc.h"
26 
27 /* Pty allocated with _getpty gets broken if we do I_PUSH:es to it. */
28 #if defined(HAVE__GETPTY) || defined(HAVE_OPENPTY)
29 #undef HAVE_DEV_PTMX
30 #endif
31 
32 #ifdef HAVE_PTY_H
33 # include <pty.h>
34 #endif
35 #if defined(HAVE_DEV_PTMX) && defined(HAVE_SYS_STROPTS_H)
36 # include <sys/stropts.h>
37 #endif
38 
39 #ifndef O_NOCTTY
40 #define O_NOCTTY 0
41 #endif
42 
43 /*
44  * Allocates and opens a pty.  Returns 0 if no pty could be allocated, or
45  * nonzero if a pty was successfully allocated.  On success, open file
46  * descriptors for the pty and tty sides and the name of the tty side are
47  * returned (the buffer must be able to hold at least 64 characters).
48  */
49 
50 int
51 pty_allocate(int *ptyfd, int *ttyfd, char *namebuf, int namebuflen)
52 {
53 #if defined(HAVE_OPENPTY) || defined(BSD4_4)
54 	/* openpty(3) exists in OSF/1 and some other os'es */
55 	char *name;
56 	int i;
57 
58 	i = openpty(ptyfd, ttyfd, NULL, NULL, NULL);
59 	if (i < 0) {
60 		error("openpty: %.100s", strerror(errno));
61 		return 0;
62 	}
63 	name = ttyname(*ttyfd);
64 	if (!name)
65 		fatal("openpty returns device for which ttyname fails.");
66 
67 	strlcpy(namebuf, name, namebuflen);	/* possible truncation */
68 	return 1;
69 #else /* HAVE_OPENPTY */
70 #ifdef HAVE__GETPTY
71 	/*
72 	 * _getpty(3) exists in SGI Irix 4.x, 5.x & 6.x -- it generates more
73 	 * pty's automagically when needed
74 	 */
75 	char *slave;
76 
77 	slave = _getpty(ptyfd, O_RDWR, 0622, 0);
78 	if (slave == NULL) {
79 		error("_getpty: %.100s", strerror(errno));
80 		return 0;
81 	}
82 	strlcpy(namebuf, slave, namebuflen);
83 	/* Open the slave side. */
84 	*ttyfd = open(namebuf, O_RDWR | O_NOCTTY);
85 	if (*ttyfd < 0) {
86 		error("%.200s: %.100s", namebuf, strerror(errno));
87 		close(*ptyfd);
88 		return 0;
89 	}
90 	return 1;
91 #else /* HAVE__GETPTY */
92 #if defined(HAVE_DEV_PTMX)
93 	/*
94 	 * This code is used e.g. on Solaris 2.x.  (Note that Solaris 2.3
95 	 * also has bsd-style ptys, but they simply do not work.)
96 	 */
97 	int ptm;
98 	char *pts;
99 	mysig_t old_signal;
100 
101 	ptm = open("/dev/ptmx", O_RDWR | O_NOCTTY);
102 	if (ptm < 0) {
103 		error("/dev/ptmx: %.100s", strerror(errno));
104 		return 0;
105 	}
106 	old_signal = mysignal(SIGCHLD, SIG_DFL);
107 	if (grantpt(ptm) < 0) {
108 		error("grantpt: %.100s", strerror(errno));
109 		return 0;
110 	}
111 	mysignal(SIGCHLD, old_signal);
112 	if (unlockpt(ptm) < 0) {
113 		error("unlockpt: %.100s", strerror(errno));
114 		return 0;
115 	}
116 	pts = ptsname(ptm);
117 	if (pts == NULL)
118 		error("Slave pty side name could not be obtained.");
119 	strlcpy(namebuf, pts, namebuflen);
120 	*ptyfd = ptm;
121 
122 	/* Open the slave side. */
123 	*ttyfd = open(namebuf, O_RDWR | O_NOCTTY);
124 	if (*ttyfd < 0) {
125 		error("%.100s: %.100s", namebuf, strerror(errno));
126 		close(*ptyfd);
127 		return 0;
128 	}
129 #ifndef HAVE_CYGWIN
130 	/*
131 	 * Push the appropriate streams modules, as described in Solaris pts(7).
132 	 * HP-UX pts(7) doesn't have ttcompat module.
133 	 */
134 	if (ioctl(*ttyfd, I_PUSH, "ptem") < 0)
135 		error("ioctl I_PUSH ptem: %.100s", strerror(errno));
136 	if (ioctl(*ttyfd, I_PUSH, "ldterm") < 0)
137 		error("ioctl I_PUSH ldterm: %.100s", strerror(errno));
138 #ifndef __hpux
139 	if (ioctl(*ttyfd, I_PUSH, "ttcompat") < 0)
140 		error("ioctl I_PUSH ttcompat: %.100s", strerror(errno));
141 #endif
142 #endif
143 	return 1;
144 #else /* HAVE_DEV_PTMX */
145 #ifdef HAVE_DEV_PTS_AND_PTC
146 	/* AIX-style pty code. */
147 	const char *name;
148 
149 	*ptyfd = open("/dev/ptc", O_RDWR | O_NOCTTY);
150 	if (*ptyfd < 0) {
151 		error("Could not open /dev/ptc: %.100s", strerror(errno));
152 		return 0;
153 	}
154 	name = ttyname(*ptyfd);
155 	if (!name)
156 		fatal("Open of /dev/ptc returns device for which ttyname fails.");
157 	strlcpy(namebuf, name, namebuflen);
158 	*ttyfd = open(name, O_RDWR | O_NOCTTY);
159 	if (*ttyfd < 0) {
160 		error("Could not open pty slave side %.100s: %.100s",
161 		    name, strerror(errno));
162 		close(*ptyfd);
163 		return 0;
164 	}
165 	return 1;
166 #else /* HAVE_DEV_PTS_AND_PTC */
167 #ifdef _UNICOS
168 	char buf[64];
169 	int i;
170 	int highpty;
171 
172 #ifdef _SC_CRAY_NPTY
173 	highpty = sysconf(_SC_CRAY_NPTY);
174 	if (highpty == -1)
175 		highpty = 128;
176 #else
177 	highpty = 128;
178 #endif
179 
180 	for (i = 0; i < highpty; i++) {
181 		snprintf(buf, sizeof(buf), "/dev/pty/%03d", i);
182 		*ptyfd = open(buf, O_RDWR|O_NOCTTY);
183 		if (*ptyfd < 0)
184 			continue;
185 		snprintf(namebuf, namebuflen, "/dev/ttyp%03d", i);
186 		/* Open the slave side. */
187 		*ttyfd = open(namebuf, O_RDWR|O_NOCTTY);
188 		if (*ttyfd < 0) {
189 			error("%.100s: %.100s", namebuf, strerror(errno));
190 			close(*ptyfd);
191 			return 0;
192 		}
193 		return 1;
194 	}
195 	return 0;
196 #else
197 	/* BSD-style pty code. */
198 	char buf[64];
199 	int i;
200 	const char *ptymajors = "pqrstuvwxyzabcdefghijklmnoABCDEFGHIJKLMNOPQRSTUVWXYZ";
201 	const char *ptyminors = "0123456789abcdef";
202 	int num_minors = strlen(ptyminors);
203 	int num_ptys = strlen(ptymajors) * num_minors;
204 	struct termios tio;
205 
206 	for (i = 0; i < num_ptys; i++) {
207 		snprintf(buf, sizeof buf, "/dev/pty%c%c", ptymajors[i / num_minors],
208 			 ptyminors[i % num_minors]);
209 		snprintf(namebuf, namebuflen, "/dev/tty%c%c",
210 		    ptymajors[i / num_minors], ptyminors[i % num_minors]);
211 
212 		*ptyfd = open(buf, O_RDWR | O_NOCTTY);
213 		if (*ptyfd < 0) {
214 			/* Try SCO style naming */
215 			snprintf(buf, sizeof buf, "/dev/ptyp%d", i);
216 			snprintf(namebuf, namebuflen, "/dev/ttyp%d", i);
217 			*ptyfd = open(buf, O_RDWR | O_NOCTTY);
218 			if (*ptyfd < 0)
219 				continue;
220 		}
221 
222 		/* Open the slave side. */
223 		*ttyfd = open(namebuf, O_RDWR | O_NOCTTY);
224 		if (*ttyfd < 0) {
225 			error("%.100s: %.100s", namebuf, strerror(errno));
226 			close(*ptyfd);
227 			return 0;
228 		}
229 		/* set tty modes to a sane state for broken clients */
230 		if (tcgetattr(*ptyfd, &tio) < 0)
231 			log("Getting tty modes for pty failed: %.100s", strerror(errno));
232 		else {
233 			tio.c_lflag |= (ECHO | ISIG | ICANON);
234 			tio.c_oflag |= (OPOST | ONLCR);
235 			tio.c_iflag |= ICRNL;
236 
237 			/* Set the new modes for the terminal. */
238 			if (tcsetattr(*ptyfd, TCSANOW, &tio) < 0)
239 				log("Setting tty modes for pty failed: %.100s", strerror(errno));
240 		}
241 
242 		return 1;
243 	}
244 	return 0;
245 #endif /* CRAY */
246 #endif /* HAVE_DEV_PTS_AND_PTC */
247 #endif /* HAVE_DEV_PTMX */
248 #endif /* HAVE__GETPTY */
249 #endif /* HAVE_OPENPTY */
250 }
251 
252 /* Releases the tty.  Its ownership is returned to root, and permissions to 0666. */
253 
254 void
255 pty_release(const char *ttyname)
256 {
257 	if (chown(ttyname, (uid_t) 0, (gid_t) 0) < 0)
258 		error("chown %.100s 0 0 failed: %.100s", ttyname, strerror(errno));
259 	if (chmod(ttyname, (mode_t) 0666) < 0)
260 		error("chmod %.100s 0666 failed: %.100s", ttyname, strerror(errno));
261 }
262 
263 /* Makes the tty the processes controlling tty and sets it to sane modes. */
264 
265 void
266 pty_make_controlling_tty(int *ttyfd, const char *ttyname)
267 {
268 	int fd;
269 #ifdef USE_VHANGUP
270 	void *old;
271 #endif /* USE_VHANGUP */
272 
273 #ifdef _UNICOS
274 	if (setsid() < 0)
275 		error("setsid: %.100s", strerror(errno));
276 
277 	fd = open(ttyname, O_RDWR|O_NOCTTY);
278 	if (fd != -1) {
279 		mysignal(SIGHUP, SIG_IGN);
280 		ioctl(fd, TCVHUP, (char *)NULL);
281 		mysignal(SIGHUP, SIG_DFL);
282 		setpgid(0, 0);
283 		close(fd);
284 	} else {
285 		error("Failed to disconnect from controlling tty.");
286 	}
287 
288 	debug("Setting controlling tty using TCSETCTTY.");
289 	ioctl(*ttyfd, TCSETCTTY, NULL);
290 	fd = open("/dev/tty", O_RDWR);
291 	if (fd < 0)
292 		error("%.100s: %.100s", ttyname, strerror(errno));
293 	close(*ttyfd);
294 	*ttyfd = fd;
295 #else /* _UNICOS */
296 
297 	/* First disconnect from the old controlling tty. */
298 #ifdef TIOCNOTTY
299 	fd = open(_PATH_TTY, O_RDWR | O_NOCTTY);
300 	if (fd >= 0) {
301 		(void) ioctl(fd, TIOCNOTTY, NULL);
302 		close(fd);
303 	}
304 #endif /* TIOCNOTTY */
305 	if (setsid() < 0)
306 		error("setsid: %.100s", strerror(errno));
307 
308 	/*
309 	 * Verify that we are successfully disconnected from the controlling
310 	 * tty.
311 	 */
312 	fd = open(_PATH_TTY, O_RDWR | O_NOCTTY);
313 	if (fd >= 0) {
314 		error("Failed to disconnect from controlling tty.");
315 		close(fd);
316 	}
317 	/* Make it our controlling tty. */
318 #ifdef TIOCSCTTY
319 	debug("Setting controlling tty using TIOCSCTTY.");
320 	if (ioctl(*ttyfd, TIOCSCTTY, NULL) < 0)
321 		error("ioctl(TIOCSCTTY): %.100s", strerror(errno));
322 #endif /* TIOCSCTTY */
323 #ifdef HAVE_NEWS4
324 	if (setpgrp(0,0) < 0)
325 		error("SETPGRP %s",strerror(errno));
326 #endif /* HAVE_NEWS4 */
327 #ifdef USE_VHANGUP
328 	old = mysignal(SIGHUP, SIG_IGN);
329 	vhangup();
330 	mysignal(SIGHUP, old);
331 #endif /* USE_VHANGUP */
332 	fd = open(ttyname, O_RDWR);
333 	if (fd < 0) {
334 		error("%.100s: %.100s", ttyname, strerror(errno));
335 	} else {
336 #ifdef USE_VHANGUP
337 		close(*ttyfd);
338 		*ttyfd = fd;
339 #else /* USE_VHANGUP */
340 		close(fd);
341 #endif /* USE_VHANGUP */
342 	}
343 	/* Verify that we now have a controlling tty. */
344 	fd = open(_PATH_TTY, O_WRONLY);
345 	if (fd < 0)
346 		error("open /dev/tty failed - could not set controlling tty: %.100s",
347 		    strerror(errno));
348 	else
349 		close(fd);
350 #endif /* _UNICOS */
351 }
352 
353 /* Changes the window size associated with the pty. */
354 
355 void
356 pty_change_window_size(int ptyfd, int row, int col,
357 	int xpixel, int ypixel)
358 {
359 	struct winsize w;
360 
361 	w.ws_row = row;
362 	w.ws_col = col;
363 	w.ws_xpixel = xpixel;
364 	w.ws_ypixel = ypixel;
365 	(void) ioctl(ptyfd, TIOCSWINSZ, &w);
366 }
367 
368 void
369 pty_setowner(struct passwd *pw, const char *ttyname)
370 {
371 	struct group *grp;
372 	gid_t gid;
373 	mode_t mode;
374 	struct stat st;
375 
376 	/* Determine the group to make the owner of the tty. */
377 	grp = getgrnam("tty");
378 	if (grp) {
379 		gid = grp->gr_gid;
380 		mode = S_IRUSR | S_IWUSR | S_IWGRP;
381 	} else {
382 		gid = pw->pw_gid;
383 		mode = S_IRUSR | S_IWUSR | S_IWGRP | S_IWOTH;
384 	}
385 
386 	/*
387 	 * Change owner and mode of the tty as required.
388 	 * Warn but continue if filesystem is read-only and the uids match/
389 	 * tty is owned by root.
390 	 */
391 	if (stat(ttyname, &st))
392 		fatal("stat(%.100s) failed: %.100s", ttyname,
393 		    strerror(errno));
394 
395 	if (st.st_uid != pw->pw_uid || st.st_gid != gid) {
396 		if (chown(ttyname, pw->pw_uid, gid) < 0) {
397 			if (errno == EROFS &&
398 			    (st.st_uid == pw->pw_uid || st.st_uid == 0))
399 				error("chown(%.100s, %u, %u) failed: %.100s",
400 				    ttyname, (u_int)pw->pw_uid, (u_int)gid,
401 				    strerror(errno));
402 			else
403 				fatal("chown(%.100s, %u, %u) failed: %.100s",
404 				    ttyname, (u_int)pw->pw_uid, (u_int)gid,
405 				    strerror(errno));
406 		}
407 	}
408 
409 	if ((st.st_mode & (S_IRWXU|S_IRWXG|S_IRWXO)) != mode) {
410 		if (chmod(ttyname, mode) < 0) {
411 			if (errno == EROFS &&
412 			    (st.st_mode & (S_IRGRP | S_IROTH)) == 0)
413 				error("chmod(%.100s, 0%o) failed: %.100s",
414 				    ttyname, mode, strerror(errno));
415 			else
416 				fatal("chmod(%.100s, 0%o) failed: %.100s",
417 				    ttyname, mode, strerror(errno));
418 		}
419 	}
420 }
421