1 /* 2 * Dropbear - a SSH2 server 3 * 4 * Copied from OpenSSH-3.5p1 source, modified by Matt Johnston 2003 5 * 6 * Author: Tatu Ylonen <ylo (at) cs.hut.fi> 7 * Copyright (c) 1995 Tatu Ylonen <ylo (at) cs.hut.fi>, Espoo, Finland 8 * All rights reserved 9 * Allocating a pseudo-terminal, and making it the controlling tty. 10 * 11 * As far as I am concerned, the code I have written for this software 12 * can be used freely for any purpose. Any derived versions of this 13 * software must be clearly marked as such, and if the derived work is 14 * incompatible with the protocol description in the RFC file, it must be 15 * called by a name other than "ssh" or "Secure Shell". 16 */ 17 18 /*RCSID("OpenBSD: sshpty.c,v 1.7 2002/06/24 17:57:20 deraadt Exp ");*/ 19 20 #include "includes.h" 21 #include "dbutil.h" 22 #include "errno.h" 23 #include "sshpty.h" 24 25 /* Pty allocated with _getpty gets broken if we do I_PUSH:es to it. */ 26 #if defined(HAVE__GETPTY) || defined(HAVE_OPENPTY) 27 #undef HAVE_DEV_PTMX 28 #endif 29 30 #ifdef HAVE_PTY_H 31 # include <pty.h> 32 #endif 33 #if defined(USE_DEV_PTMX) && defined(HAVE_STROPTS_H) 34 # include <stropts.h> 35 #endif 36 37 #ifndef O_NOCTTY 38 #define O_NOCTTY 0 39 #endif 40 41 /* 42 * Allocates and opens a pty. Returns 0 if no pty could be allocated, or 43 * nonzero if a pty was successfully allocated. On success, open file 44 * descriptors for the pty and tty sides and the name of the tty side are 45 * returned (the buffer must be able to hold at least 64 characters). 46 */ 47 48 int 49 pty_allocate(int *ptyfd, int *ttyfd, char *namebuf, int namebuflen) 50 { 51 #if defined(HAVE_OPENPTY) 52 /* exists in recent (4.4) BSDs and OSF/1 */ 53 char *name; 54 int i; 55 56 i = openpty(ptyfd, ttyfd, NULL, NULL, NULL); 57 if (i < 0) { 58 dropbear_log(LOG_WARNING, 59 "pty_allocate: openpty: %.100s", strerror(errno)); 60 return 0; 61 } 62 name = ttyname(*ttyfd); 63 if (!name) { 64 dropbear_exit("ttyname fails for openpty device"); 65 } 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 dropbear_log(LOG_WARNING, 80 "pty_allocate: _getpty: %.100s", strerror(errno)); 81 return 0; 82 } 83 strlcpy(namebuf, slave, namebuflen); 84 /* Open the slave side. */ 85 *ttyfd = open(namebuf, O_RDWR | O_NOCTTY); 86 if (*ttyfd < 0) { 87 dropbear_log(LOG_WARNING, 88 "pty_allocate error: ttyftd open error"); 89 close(*ptyfd); 90 return 0; 91 } 92 return 1; 93 #else /* HAVE__GETPTY */ 94 #if defined(USE_DEV_PTMX) 95 /* 96 * This code is used e.g. on Solaris 2.x. (Note that Solaris 2.3 97 * also has bsd-style ptys, but they simply do not work.) 98 * 99 * Linux systems may have the /dev/ptmx device, but this code won't work. 100 */ 101 int ptm; 102 char *pts; 103 104 ptm = open("/dev/ptmx", O_RDWR | O_NOCTTY); 105 if (ptm < 0) { 106 dropbear_log(LOG_WARNING, 107 "pty_allocate: /dev/ptmx: %.100s", strerror(errno)); 108 return 0; 109 } 110 if (grantpt(ptm) < 0) { 111 dropbear_log(LOG_WARNING, 112 "grantpt: %.100s", strerror(errno)); 113 return 0; 114 } 115 if (unlockpt(ptm) < 0) { 116 dropbear_log(LOG_WARNING, 117 "unlockpt: %.100s", strerror(errno)); 118 return 0; 119 } 120 pts = ptsname(ptm); 121 if (pts == NULL) { 122 dropbear_log(LOG_WARNING, 123 "Slave pty side name could not be obtained."); 124 } 125 strlcpy(namebuf, pts, namebuflen); 126 *ptyfd = ptm; 127 128 /* Open the slave side. */ 129 *ttyfd = open(namebuf, O_RDWR | O_NOCTTY); 130 if (*ttyfd < 0) { 131 dropbear_log(LOG_ERR, 132 "error opening pts %.100s: %.100s", namebuf, strerror(errno)); 133 close(*ptyfd); 134 return 0; 135 } 136 #ifndef HAVE_CYGWIN 137 /* 138 * Push the appropriate streams modules, as described in Solaris pts(7). 139 * HP-UX pts(7) doesn't have ttcompat module. 140 */ 141 if (ioctl(*ttyfd, I_PUSH, "ptem") < 0) { 142 dropbear_log(LOG_WARNING, 143 "ioctl I_PUSH ptem: %.100s", strerror(errno)); 144 } 145 if (ioctl(*ttyfd, I_PUSH, "ldterm") < 0) { 146 dropbear_log(LOG_WARNING, 147 "ioctl I_PUSH ldterm: %.100s", strerror(errno)); 148 } 149 #ifndef __hpux 150 if (ioctl(*ttyfd, I_PUSH, "ttcompat") < 0) { 151 dropbear_log(LOG_WARNING, 152 "ioctl I_PUSH ttcompat: %.100s", strerror(errno)); 153 } 154 #endif 155 #endif 156 return 1; 157 #else /* USE_DEV_PTMX */ 158 #ifdef HAVE_DEV_PTS_AND_PTC 159 /* AIX-style pty code. */ 160 const char *name; 161 162 *ptyfd = open("/dev/ptc", O_RDWR | O_NOCTTY); 163 if (*ptyfd < 0) { 164 dropbear_log(LOG_ERR, 165 "Could not open /dev/ptc: %.100s", strerror(errno)); 166 return 0; 167 } 168 name = ttyname(*ptyfd); 169 if (!name) { 170 dropbear_exit("ttyname fails for /dev/ptc device"); 171 } 172 strlcpy(namebuf, name, namebuflen); 173 *ttyfd = open(name, O_RDWR | O_NOCTTY); 174 if (*ttyfd < 0) { 175 dropbear_log(LOG_ERR, 176 "Could not open pty slave side %.100s: %.100s", 177 name, strerror(errno)); 178 close(*ptyfd); 179 return 0; 180 } 181 return 1; 182 #else /* HAVE_DEV_PTS_AND_PTC */ 183 184 /* BSD-style pty code. */ 185 char buf[64]; 186 int i; 187 const char *ptymajors = "pqrstuvwxyzabcdefghijklmnoABCDEFGHIJKLMNOPQRSTUVWXYZ"; 188 const char *ptyminors = "0123456789abcdef"; 189 int num_minors = strlen(ptyminors); 190 int num_ptys = strlen(ptymajors) * num_minors; 191 struct termios tio; 192 193 for (i = 0; i < num_ptys; i++) { 194 snprintf(buf, sizeof buf, "/dev/pty%c%c", ptymajors[i / num_minors], 195 ptyminors[i % num_minors]); 196 snprintf(namebuf, namebuflen, "/dev/tty%c%c", 197 ptymajors[i / num_minors], ptyminors[i % num_minors]); 198 199 *ptyfd = open(buf, O_RDWR | O_NOCTTY); 200 if (*ptyfd < 0) { 201 /* Try SCO style naming */ 202 snprintf(buf, sizeof buf, "/dev/ptyp%d", i); 203 snprintf(namebuf, namebuflen, "/dev/ttyp%d", i); 204 *ptyfd = open(buf, O_RDWR | O_NOCTTY); 205 if (*ptyfd < 0) { 206 continue; 207 } 208 } 209 210 /* Open the slave side. */ 211 *ttyfd = open(namebuf, O_RDWR | O_NOCTTY); 212 if (*ttyfd < 0) { 213 dropbear_log(LOG_ERR, 214 "pty_allocate: %.100s: %.100s", namebuf, strerror(errno)); 215 close(*ptyfd); 216 return 0; 217 } 218 /* set tty modes to a sane state for broken clients */ 219 if (tcgetattr(*ptyfd, &tio) < 0) { 220 dropbear_log(LOG_WARNING, 221 "ptyallocate: tty modes failed: %.100s", strerror(errno)); 222 } else { 223 tio.c_lflag |= (ECHO | ISIG | ICANON); 224 tio.c_oflag |= (OPOST | ONLCR); 225 tio.c_iflag |= ICRNL; 226 227 /* Set the new modes for the terminal. */ 228 if (tcsetattr(*ptyfd, TCSANOW, &tio) < 0) { 229 dropbear_log(LOG_WARNING, 230 "Setting tty modes for pty failed: %.100s", 231 strerror(errno)); 232 } 233 } 234 235 return 1; 236 } 237 dropbear_log(LOG_WARNING, "failed to open any /dev/pty?? devices"); 238 return 0; 239 #endif /* HAVE_DEV_PTS_AND_PTC */ 240 #endif /* USE_DEV_PTMX */ 241 #endif /* HAVE__GETPTY */ 242 #endif /* HAVE_OPENPTY */ 243 } 244 245 /* Releases the tty. Its ownership is returned to root, and permissions to 0666. */ 246 247 void 248 pty_release(const char *tty_name) 249 { 250 if (chown(tty_name, (uid_t) 0, (gid_t) 0) < 0 251 && (errno != ENOENT)) { 252 dropbear_log(LOG_ERR, 253 "chown %.100s 0 0 failed: %.100s", tty_name, strerror(errno)); 254 } 255 if (chmod(tty_name, (mode_t) 0666) < 0 256 && (errno != ENOENT)) { 257 dropbear_log(LOG_ERR, 258 "chmod %.100s 0666 failed: %.100s", tty_name, strerror(errno)); 259 } 260 } 261 262 /* Makes the tty the processes controlling tty and sets it to sane modes. */ 263 264 void 265 pty_make_controlling_tty(int *ttyfd, const char *tty_name) 266 { 267 int fd; 268 #ifdef USE_VHANGUP 269 void *old; 270 #endif /* USE_VHANGUP */ 271 272 /* Solaris has a problem with TIOCNOTTY for a bg process, so 273 * we disable the signal which would STOP the process - matt */ 274 signal(SIGTTOU, SIG_IGN); 275 276 /* First disconnect from the old controlling tty. */ 277 #ifdef TIOCNOTTY 278 fd = open(_PATH_TTY, O_RDWR | O_NOCTTY); 279 if (fd >= 0) { 280 (void) ioctl(fd, TIOCNOTTY, NULL); 281 close(fd); 282 } 283 #endif /* TIOCNOTTY */ 284 if (setsid() < 0) { 285 dropbear_log(LOG_ERR, 286 "setsid: %.100s", strerror(errno)); 287 } 288 289 /* 290 * Verify that we are successfully disconnected from the controlling 291 * tty. 292 */ 293 fd = open(_PATH_TTY, O_RDWR | O_NOCTTY); 294 if (fd >= 0) { 295 dropbear_log(LOG_ERR, 296 "Failed to disconnect from controlling tty.\n"); 297 close(fd); 298 } 299 /* Make it our controlling tty. */ 300 #ifdef TIOCSCTTY 301 if (ioctl(*ttyfd, TIOCSCTTY, NULL) < 0) { 302 dropbear_log(LOG_ERR, 303 "ioctl(TIOCSCTTY): %.100s", strerror(errno)); 304 } 305 #endif /* TIOCSCTTY */ 306 #ifdef HAVE_NEWS4 307 if (setpgrp(0,0) < 0) { 308 dropbear_log(LOG_ERR, 309 error("SETPGRP %s",strerror(errno))); 310 } 311 #endif /* HAVE_NEWS4 */ 312 #ifdef USE_VHANGUP 313 old = mysignal(SIGHUP, SIG_IGN); 314 vhangup(); 315 mysignal(SIGHUP, old); 316 #endif /* USE_VHANGUP */ 317 fd = open(tty_name, O_RDWR); 318 if (fd < 0) { 319 dropbear_log(LOG_ERR, 320 "%.100s: %.100s", tty_name, strerror(errno)); 321 } else { 322 #ifdef USE_VHANGUP 323 close(*ttyfd); 324 *ttyfd = fd; 325 #else /* USE_VHANGUP */ 326 close(fd); 327 #endif /* USE_VHANGUP */ 328 } 329 /* Verify that we now have a controlling tty. */ 330 fd = open(_PATH_TTY, O_WRONLY); 331 if (fd < 0) { 332 dropbear_log(LOG_ERR, 333 "open /dev/tty failed - could not set controlling tty: %.100s", 334 strerror(errno)); 335 } else { 336 close(fd); 337 } 338 } 339 340 /* Changes the window size associated with the pty. */ 341 342 void 343 pty_change_window_size(int ptyfd, int row, int col, 344 int xpixel, int ypixel) 345 { 346 struct winsize w; 347 348 w.ws_row = row; 349 w.ws_col = col; 350 w.ws_xpixel = xpixel; 351 w.ws_ypixel = ypixel; 352 (void) ioctl(ptyfd, TIOCSWINSZ, &w); 353 } 354 355 void 356 pty_setowner(struct passwd *pw, const char *tty_name) 357 { 358 struct group *grp; 359 gid_t gid; 360 mode_t mode; 361 struct stat st; 362 363 /* Determine the group to make the owner of the tty. */ 364 grp = getgrnam("tty"); 365 if (grp) { 366 gid = grp->gr_gid; 367 mode = S_IRUSR | S_IWUSR | S_IWGRP; 368 } else { 369 gid = pw->pw_gid; 370 mode = S_IRUSR | S_IWUSR | S_IWGRP | S_IWOTH; 371 } 372 373 /* 374 * Change owner and mode of the tty as required. 375 * Warn but continue if filesystem is read-only and the uids match/ 376 * tty is owned by root. 377 */ 378 if (stat(tty_name, &st)) { 379 dropbear_exit("pty_setowner: stat(%.101s) failed: %.100s", 380 tty_name, strerror(errno)); 381 } 382 383 if (st.st_uid != pw->pw_uid || st.st_gid != gid) { 384 if (chown(tty_name, pw->pw_uid, gid) < 0) { 385 if (errno == EROFS && 386 (st.st_uid == pw->pw_uid || st.st_uid == 0)) { 387 dropbear_log(LOG_ERR, 388 "chown(%.100s, %u, %u) failed: %.100s", 389 tty_name, (unsigned int)pw->pw_uid, (unsigned int)gid, 390 strerror(errno)); 391 } else { 392 dropbear_exit("chown(%.100s, %u, %u) failed: %.100s", 393 tty_name, (unsigned int)pw->pw_uid, (unsigned int)gid, 394 strerror(errno)); 395 } 396 } 397 } 398 399 if ((st.st_mode & (S_IRWXU|S_IRWXG|S_IRWXO)) != mode) { 400 if (chmod(tty_name, mode) < 0) { 401 if (errno == EROFS && 402 (st.st_mode & (S_IRGRP | S_IROTH)) == 0) { 403 dropbear_log(LOG_ERR, 404 "chmod(%.100s, 0%o) failed: %.100s", 405 tty_name, mode, strerror(errno)); 406 } else { 407 dropbear_exit("chmod(%.100s, 0%o) failed: %.100s", 408 tty_name, mode, strerror(errno)); 409 } 410 } 411 } 412 } 413
