xref: /openssh-portable/ttymodes.c (revision 4ca6a1fa)
1 /* $OpenBSD: ttymodes.c,v 1.36 2021/01/27 09:26:54 djm Exp $ */
2 /*
3  * Author: Tatu Ylonen <ylo@cs.hut.fi>
4  * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
5  *                    All rights reserved
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 /*
15  * SSH2 tty modes support by Kevin Steves.
16  * Copyright (c) 2001 Kevin Steves.  All rights reserved.
17  *
18  * Redistribution and use in source and binary forms, with or without
19  * modification, are permitted provided that the following conditions
20  * are met:
21  * 1. Redistributions of source code must retain the above copyright
22  *    notice, this list of conditions and the following disclaimer.
23  * 2. Redistributions in binary form must reproduce the above copyright
24  *    notice, this list of conditions and the following disclaimer in the
25  *    documentation and/or other materials provided with the distribution.
26  *
27  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
28  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
29  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
30  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
31  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
32  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
33  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
34  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
35  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
36  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
37  */
38 
39 /*
40  * Encoding and decoding of terminal modes in a portable way.
41  * Much of the format is defined in ttymodes.h; it is included multiple times
42  * into this file with the appropriate macro definitions to generate the
43  * suitable code.
44  */
45 
46 #include "includes.h"
47 
48 #include <sys/types.h>
49 
50 #include <errno.h>
51 #include <string.h>
52 #include <termios.h>
53 #include <stdarg.h>
54 
55 #include "packet.h"
56 #include "log.h"
57 #include "compat.h"
58 #include "sshbuf.h"
59 #include "ssherr.h"
60 
61 #define TTY_OP_END		0
62 /*
63  * uint32 (u_int) follows speed.
64  */
65 #define TTY_OP_ISPEED	128
66 #define TTY_OP_OSPEED	129
67 
68 /*
69  * Converts POSIX speed_t to a baud rate.  The values of the
70  * constants for speed_t are not themselves portable.
71  */
72 static int
speed_to_baud(speed_t speed)73 speed_to_baud(speed_t speed)
74 {
75 	switch (speed) {
76 	case B0:
77 		return 0;
78 	case B50:
79 		return 50;
80 	case B75:
81 		return 75;
82 	case B110:
83 		return 110;
84 	case B134:
85 		return 134;
86 	case B150:
87 		return 150;
88 	case B200:
89 		return 200;
90 	case B300:
91 		return 300;
92 	case B600:
93 		return 600;
94 	case B1200:
95 		return 1200;
96 	case B1800:
97 		return 1800;
98 	case B2400:
99 		return 2400;
100 	case B4800:
101 		return 4800;
102 	case B9600:
103 		return 9600;
104 
105 #ifdef B19200
106 	case B19200:
107 		return 19200;
108 #else /* B19200 */
109 #ifdef EXTA
110 	case EXTA:
111 		return 19200;
112 #endif /* EXTA */
113 #endif /* B19200 */
114 
115 #ifdef B38400
116 	case B38400:
117 		return 38400;
118 #else /* B38400 */
119 #ifdef EXTB
120 	case EXTB:
121 		return 38400;
122 #endif /* EXTB */
123 #endif /* B38400 */
124 
125 #ifdef B7200
126 	case B7200:
127 		return 7200;
128 #endif /* B7200 */
129 #ifdef B14400
130 	case B14400:
131 		return 14400;
132 #endif /* B14400 */
133 #ifdef B28800
134 	case B28800:
135 		return 28800;
136 #endif /* B28800 */
137 #ifdef B57600
138 	case B57600:
139 		return 57600;
140 #endif /* B57600 */
141 #ifdef B76800
142 	case B76800:
143 		return 76800;
144 #endif /* B76800 */
145 #ifdef B115200
146 	case B115200:
147 		return 115200;
148 #endif /* B115200 */
149 #ifdef B230400
150 	case B230400:
151 		return 230400;
152 #endif /* B230400 */
153 	default:
154 		return 9600;
155 	}
156 }
157 
158 /*
159  * Converts a numeric baud rate to a POSIX speed_t.
160  */
161 static speed_t
baud_to_speed(int baud)162 baud_to_speed(int baud)
163 {
164 	switch (baud) {
165 	case 0:
166 		return B0;
167 	case 50:
168 		return B50;
169 	case 75:
170 		return B75;
171 	case 110:
172 		return B110;
173 	case 134:
174 		return B134;
175 	case 150:
176 		return B150;
177 	case 200:
178 		return B200;
179 	case 300:
180 		return B300;
181 	case 600:
182 		return B600;
183 	case 1200:
184 		return B1200;
185 	case 1800:
186 		return B1800;
187 	case 2400:
188 		return B2400;
189 	case 4800:
190 		return B4800;
191 	case 9600:
192 		return B9600;
193 
194 #ifdef B19200
195 	case 19200:
196 		return B19200;
197 #else /* B19200 */
198 #ifdef EXTA
199 	case 19200:
200 		return EXTA;
201 #endif /* EXTA */
202 #endif /* B19200 */
203 
204 #ifdef B38400
205 	case 38400:
206 		return B38400;
207 #else /* B38400 */
208 #ifdef EXTB
209 	case 38400:
210 		return EXTB;
211 #endif /* EXTB */
212 #endif /* B38400 */
213 
214 #ifdef B7200
215 	case 7200:
216 		return B7200;
217 #endif /* B7200 */
218 #ifdef B14400
219 	case 14400:
220 		return B14400;
221 #endif /* B14400 */
222 #ifdef B28800
223 	case 28800:
224 		return B28800;
225 #endif /* B28800 */
226 #ifdef B57600
227 	case 57600:
228 		return B57600;
229 #endif /* B57600 */
230 #ifdef B76800
231 	case 76800:
232 		return B76800;
233 #endif /* B76800 */
234 #ifdef B115200
235 	case 115200:
236 		return B115200;
237 #endif /* B115200 */
238 #ifdef B230400
239 	case 230400:
240 		return B230400;
241 #endif /* B230400 */
242 	default:
243 		return B9600;
244 	}
245 }
246 
247 /*
248  * Encode a special character into SSH line format.
249  */
250 static u_int
special_char_encode(cc_t c)251 special_char_encode(cc_t c)
252 {
253 #ifdef _POSIX_VDISABLE
254 	if (c == _POSIX_VDISABLE)
255 		return 255;
256 #endif /* _POSIX_VDISABLE */
257 	return c;
258 }
259 
260 /*
261  * Decode a special character from SSH line format.
262  */
263 static cc_t
special_char_decode(u_int c)264 special_char_decode(u_int c)
265 {
266 #ifdef _POSIX_VDISABLE
267 	if (c == 255)
268 		return _POSIX_VDISABLE;
269 #endif /* _POSIX_VDISABLE */
270 	return c;
271 }
272 
273 /*
274  * Encodes terminal modes for the terminal referenced by fd
275  * or tiop in a portable manner, and appends the modes to a packet
276  * being constructed.
277  */
278 void
ssh_tty_make_modes(struct ssh * ssh,int fd,struct termios * tiop)279 ssh_tty_make_modes(struct ssh *ssh, int fd, struct termios *tiop)
280 {
281 	struct termios tio;
282 	struct sshbuf *buf;
283 	int r, ibaud, obaud;
284 
285 	if ((buf = sshbuf_new()) == NULL)
286 		fatal_f("sshbuf_new failed");
287 
288 	if (tiop == NULL) {
289 		if (fd == -1) {
290 			debug_f("no fd or tio");
291 			goto end;
292 		}
293 		if (tcgetattr(fd, &tio) == -1) {
294 			logit("tcgetattr: %.100s", strerror(errno));
295 			goto end;
296 		}
297 	} else
298 		tio = *tiop;
299 
300 	/* Store input and output baud rates. */
301 	obaud = speed_to_baud(cfgetospeed(&tio));
302 	ibaud = speed_to_baud(cfgetispeed(&tio));
303 	if ((r = sshbuf_put_u8(buf, TTY_OP_OSPEED)) != 0 ||
304 	    (r = sshbuf_put_u32(buf, obaud)) != 0 ||
305 	    (r = sshbuf_put_u8(buf, TTY_OP_ISPEED)) != 0 ||
306 	    (r = sshbuf_put_u32(buf, ibaud)) != 0)
307 		fatal_fr(r, "compose");
308 
309 	/* Store values of mode flags. */
310 #define TTYCHAR(NAME, OP) \
311 	if ((r = sshbuf_put_u8(buf, OP)) != 0 || \
312 	    (r = sshbuf_put_u32(buf, \
313 	    special_char_encode(tio.c_cc[NAME]))) != 0) \
314 		fatal_fr(r, "compose %s", #NAME);
315 
316 #define SSH_TTYMODE_IUTF8 42  /* for SSH_BUG_UTF8TTYMODE */
317 
318 #define TTYMODE(NAME, FIELD, OP) \
319 	if (OP == SSH_TTYMODE_IUTF8 && (ssh->compat & SSH_BUG_UTF8TTYMODE)) { \
320 		debug3_f("SSH_BUG_UTF8TTYMODE"); \
321 	} else if ((r = sshbuf_put_u8(buf, OP)) != 0 || \
322 	    (r = sshbuf_put_u32(buf, ((tio.FIELD & NAME) != 0))) != 0) \
323 		fatal_fr(r, "compose %s", #NAME);
324 
325 #include "ttymodes.h"
326 
327 #undef TTYCHAR
328 #undef TTYMODE
329 
330 end:
331 	/* Mark end of mode data. */
332 	if ((r = sshbuf_put_u8(buf, TTY_OP_END)) != 0 ||
333 	    (r = sshpkt_put_stringb(ssh, buf)) != 0)
334 		fatal_fr(r, "compose end");
335 	sshbuf_free(buf);
336 }
337 
338 /*
339  * Decodes terminal modes for the terminal referenced by fd in a portable
340  * manner from a packet being read.
341  */
342 void
ssh_tty_parse_modes(struct ssh * ssh,int fd)343 ssh_tty_parse_modes(struct ssh *ssh, int fd)
344 {
345 	struct termios tio;
346 	struct sshbuf *buf;
347 	const u_char *data;
348 	u_char opcode;
349 	u_int baud, u;
350 	int r, failure = 0;
351 	size_t len;
352 
353 	if ((r = sshpkt_get_string_direct(ssh, &data, &len)) != 0)
354 		fatal_fr(r, "parse");
355 	if (len == 0)
356 		return;
357 	if ((buf = sshbuf_from(data, len)) == NULL) {
358 		error_f("sshbuf_from failed");
359 		return;
360 	}
361 
362 	/*
363 	 * Get old attributes for the terminal.  We will modify these
364 	 * flags. I am hoping that if there are any machine-specific
365 	 * modes, they will initially have reasonable values.
366 	 */
367 	if (tcgetattr(fd, &tio) == -1) {
368 		logit("tcgetattr: %.100s", strerror(errno));
369 		failure = -1;
370 	}
371 
372 	while (sshbuf_len(buf) > 0) {
373 		if ((r = sshbuf_get_u8(buf, &opcode)) != 0)
374 			fatal_fr(r, "parse opcode");
375 		switch (opcode) {
376 		case TTY_OP_END:
377 			goto set;
378 
379 		case TTY_OP_ISPEED:
380 			if ((r = sshbuf_get_u32(buf, &baud)) != 0)
381 				fatal_fr(r, "parse ispeed");
382 			if (failure != -1 &&
383 			    cfsetispeed(&tio, baud_to_speed(baud)) == -1)
384 				error("cfsetispeed failed for %d", baud);
385 			break;
386 
387 		case TTY_OP_OSPEED:
388 			if ((r = sshbuf_get_u32(buf, &baud)) != 0)
389 				fatal_fr(r, "parse ospeed");
390 			if (failure != -1 &&
391 			    cfsetospeed(&tio, baud_to_speed(baud)) == -1)
392 				error("cfsetospeed failed for %d", baud);
393 			break;
394 
395 #define TTYCHAR(NAME, OP) \
396 		case OP: \
397 			if ((r = sshbuf_get_u32(buf, &u)) != 0) \
398 				fatal_fr(r, "parse %s", #NAME); \
399 			tio.c_cc[NAME] = special_char_decode(u); \
400 			break;
401 #define TTYMODE(NAME, FIELD, OP) \
402 		case OP: \
403 			if ((r = sshbuf_get_u32(buf, &u)) != 0) \
404 				fatal_fr(r, "parse %s", #NAME); \
405 			if (u) \
406 				tio.FIELD |= NAME; \
407 			else \
408 				tio.FIELD &= ~NAME; \
409 			break;
410 
411 #include "ttymodes.h"
412 
413 #undef TTYCHAR
414 #undef TTYMODE
415 
416 		default:
417 			debug("Ignoring unsupported tty mode opcode %d (0x%x)",
418 			    opcode, opcode);
419 			/*
420 			 * SSH2:
421 			 * Opcodes 1 to 159 are defined to have a uint32
422 			 * argument.
423 			 * Opcodes 160 to 255 are undefined and cause parsing
424 			 * to stop.
425 			 */
426 			if (opcode > 0 && opcode < 160) {
427 				if ((r = sshbuf_get_u32(buf, NULL)) != 0)
428 					fatal_fr(r, "parse arg");
429 				break;
430 			} else {
431 				logit_f("unknown opcode %d", opcode);
432 				goto set;
433 			}
434 		}
435 	}
436 
437 set:
438 	len = sshbuf_len(buf);
439 	sshbuf_free(buf);
440 	if (len > 0) {
441 		logit_f("%zu bytes left", len);
442 		return;		/* Don't process bytes passed */
443 	}
444 	if (failure == -1)
445 		return;		/* Packet parsed ok but tcgetattr() failed */
446 
447 	/* Set the new modes for the terminal. */
448 	if (tcsetattr(fd, TCSANOW, &tio) == -1)
449 		logit("Setting tty modes failed: %.100s", strerror(errno));
450 }
451