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