ttymodes.c

   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
  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
 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
 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
 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
 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
 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 }