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 1.8 2003/02/03 08:56:16 markus Exp $"); 16 17 #ifdef HAVE_UTIL_H 18 # include <util.h> 19 #endif /* HAVE_UTIL_H */ 20 21 #include "sshpty.h" 22 #include "log.h" 23 #include "misc.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(HAVE_DEV_PTMX) && defined(HAVE_SYS_STROPTS_H) 34 # include <sys/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) || defined(BSD4_4) 52 /* openpty(3) exists in OSF/1 and some other os'es */ 53 char *name; 54 int i; 55 56 i = openpty(ptyfd, ttyfd, NULL, NULL, NULL); 57 if (i < 0) { 58 error("openpty: %.100s", strerror(errno)); 59 return 0; 60 } 61 name = ttyname(*ttyfd); 62 if (!name) 63 fatal("openpty returns device for which ttyname fails."); 64 65 strlcpy(namebuf, name, namebuflen); /* possible truncation */ 66 return 1; 67 #else /* HAVE_OPENPTY */ 68 #ifdef HAVE__GETPTY 69 /* 70 * _getpty(3) exists in SGI Irix 4.x, 5.x & 6.x -- it generates more 71 * pty's automagically when needed 72 */ 73 char *slave; 74 75 slave = _getpty(ptyfd, O_RDWR, 0622, 0); 76 if (slave == NULL) { 77 error("_getpty: %.100s", strerror(errno)); 78 return 0; 79 } 80 strlcpy(namebuf, slave, namebuflen); 81 /* Open the slave side. */ 82 *ttyfd = open(namebuf, O_RDWR | O_NOCTTY); 83 if (*ttyfd < 0) { 84 error("%.200s: %.100s", namebuf, strerror(errno)); 85 close(*ptyfd); 86 return 0; 87 } 88 return 1; 89 #else /* HAVE__GETPTY */ 90 #if defined(HAVE_DEV_PTMX) 91 /* 92 * This code is used e.g. on Solaris 2.x. (Note that Solaris 2.3 93 * also has bsd-style ptys, but they simply do not work.) 94 */ 95 int ptm; 96 char *pts; 97 mysig_t old_signal; 98 99 ptm = open("/dev/ptmx", O_RDWR | O_NOCTTY); 100 if (ptm < 0) { 101 error("/dev/ptmx: %.100s", strerror(errno)); 102 return 0; 103 } 104 old_signal = mysignal(SIGCHLD, SIG_DFL); 105 if (grantpt(ptm) < 0) { 106 error("grantpt: %.100s", strerror(errno)); 107 return 0; 108 } 109 mysignal(SIGCHLD, old_signal); 110 if (unlockpt(ptm) < 0) { 111 error("unlockpt: %.100s", strerror(errno)); 112 return 0; 113 } 114 pts = ptsname(ptm); 115 if (pts == NULL) 116 error("Slave pty side name could not be obtained."); 117 strlcpy(namebuf, pts, namebuflen); 118 *ptyfd = ptm; 119 120 /* Open the slave side. */ 121 *ttyfd = open(namebuf, O_RDWR | O_NOCTTY); 122 if (*ttyfd < 0) { 123 error("%.100s: %.100s", namebuf, strerror(errno)); 124 close(*ptyfd); 125 return 0; 126 } 127 #ifndef HAVE_CYGWIN 128 /* 129 * Push the appropriate streams modules, as described in Solaris pts(7). 130 * HP-UX pts(7) doesn't have ttcompat module. 131 */ 132 if (ioctl(*ttyfd, I_PUSH, "ptem") < 0) 133 error("ioctl I_PUSH ptem: %.100s", strerror(errno)); 134 if (ioctl(*ttyfd, I_PUSH, "ldterm") < 0) 135 error("ioctl I_PUSH ldterm: %.100s", strerror(errno)); 136 #ifndef __hpux 137 if (ioctl(*ttyfd, I_PUSH, "ttcompat") < 0) 138 error("ioctl I_PUSH ttcompat: %.100s", strerror(errno)); 139 #endif 140 #endif 141 return 1; 142 #else /* HAVE_DEV_PTMX */ 143 #ifdef HAVE_DEV_PTS_AND_PTC 144 /* AIX-style pty code. */ 145 const char *name; 146 147 *ptyfd = open("/dev/ptc", O_RDWR | O_NOCTTY); 148 if (*ptyfd < 0) { 149 error("Could not open /dev/ptc: %.100s", strerror(errno)); 150 return 0; 151 } 152 name = ttyname(*ptyfd); 153 if (!name) 154 fatal("Open of /dev/ptc returns device for which ttyname fails."); 155 strlcpy(namebuf, name, namebuflen); 156 *ttyfd = open(name, O_RDWR | O_NOCTTY); 157 if (*ttyfd < 0) { 158 error("Could not open pty slave side %.100s: %.100s", 159 name, strerror(errno)); 160 close(*ptyfd); 161 return 0; 162 } 163 return 1; 164 #else /* HAVE_DEV_PTS_AND_PTC */ 165 #ifdef _UNICOS 166 char buf[64]; 167 int i; 168 int highpty; 169 170 #ifdef _SC_CRAY_NPTY 171 highpty = sysconf(_SC_CRAY_NPTY); 172 if (highpty == -1) 173 highpty = 128; 174 #else 175 highpty = 128; 176 #endif 177 178 for (i = 0; i < highpty; i++) { 179 snprintf(buf, sizeof(buf), "/dev/pty/%03d", i); 180 *ptyfd = open(buf, O_RDWR|O_NOCTTY); 181 if (*ptyfd < 0) 182 continue; 183 snprintf(namebuf, namebuflen, "/dev/ttyp%03d", i); 184 /* Open the slave side. */ 185 *ttyfd = open(namebuf, O_RDWR|O_NOCTTY); 186 if (*ttyfd < 0) { 187 error("%.100s: %.100s", namebuf, strerror(errno)); 188 close(*ptyfd); 189 return 0; 190 } 191 return 1; 192 } 193 return 0; 194 #else 195 /* BSD-style pty code. */ 196 char buf[64]; 197 int i; 198 const char *ptymajors = "pqrstuvwxyzabcdefghijklmnoABCDEFGHIJKLMNOPQRSTUVWXYZ"; 199 const char *ptyminors = "0123456789abcdef"; 200 int num_minors = strlen(ptyminors); 201 int num_ptys = strlen(ptymajors) * num_minors; 202 struct termios tio; 203 204 for (i = 0; i < num_ptys; i++) { 205 snprintf(buf, sizeof buf, "/dev/pty%c%c", ptymajors[i / num_minors], 206 ptyminors[i % num_minors]); 207 snprintf(namebuf, namebuflen, "/dev/tty%c%c", 208 ptymajors[i / num_minors], ptyminors[i % num_minors]); 209 210 *ptyfd = open(buf, O_RDWR | O_NOCTTY); 211 if (*ptyfd < 0) { 212 /* Try SCO style naming */ 213 snprintf(buf, sizeof buf, "/dev/ptyp%d", i); 214 snprintf(namebuf, namebuflen, "/dev/ttyp%d", i); 215 *ptyfd = open(buf, O_RDWR | O_NOCTTY); 216 if (*ptyfd < 0) 217 continue; 218 } 219 220 /* Open the slave side. */ 221 *ttyfd = open(namebuf, O_RDWR | O_NOCTTY); 222 if (*ttyfd < 0) { 223 error("%.100s: %.100s", namebuf, strerror(errno)); 224 close(*ptyfd); 225 return 0; 226 } 227 /* set tty modes to a sane state for broken clients */ 228 if (tcgetattr(*ptyfd, &tio) < 0) 229 log("Getting tty modes for pty failed: %.100s", strerror(errno)); 230 else { 231 tio.c_lflag |= (ECHO | ISIG | ICANON); 232 tio.c_oflag |= (OPOST | ONLCR); 233 tio.c_iflag |= ICRNL; 234 235 /* Set the new modes for the terminal. */ 236 if (tcsetattr(*ptyfd, TCSANOW, &tio) < 0) 237 log("Setting tty modes for pty failed: %.100s", strerror(errno)); 238 } 239 240 return 1; 241 } 242 return 0; 243 #endif /* CRAY */ 244 #endif /* HAVE_DEV_PTS_AND_PTC */ 245 #endif /* HAVE_DEV_PTMX */ 246 #endif /* HAVE__GETPTY */ 247 #endif /* HAVE_OPENPTY */ 248 } 249 250 /* Releases the tty. Its ownership is returned to root, and permissions to 0666. */ 251 252 void 253 pty_release(const char *ttyname) 254 { 255 if (chown(ttyname, (uid_t) 0, (gid_t) 0) < 0) 256 error("chown %.100s 0 0 failed: %.100s", ttyname, strerror(errno)); 257 if (chmod(ttyname, (mode_t) 0666) < 0) 258 error("chmod %.100s 0666 failed: %.100s", ttyname, strerror(errno)); 259 } 260 261 /* Makes the tty the processes controlling tty and sets it to sane modes. */ 262 263 void 264 pty_make_controlling_tty(int *ttyfd, const char *ttyname) 265 { 266 int fd; 267 #ifdef USE_VHANGUP 268 void *old; 269 #endif /* USE_VHANGUP */ 270 271 #ifdef _UNICOS 272 if (setsid() < 0) 273 error("setsid: %.100s", strerror(errno)); 274 275 fd = open(ttyname, O_RDWR|O_NOCTTY); 276 if (fd != -1) { 277 mysignal(SIGHUP, SIG_IGN); 278 ioctl(fd, TCVHUP, (char *)NULL); 279 mysignal(SIGHUP, SIG_DFL); 280 setpgid(0, 0); 281 close(fd); 282 } else { 283 error("Failed to disconnect from controlling tty."); 284 } 285 286 debug("Setting controlling tty using TCSETCTTY."); 287 ioctl(*ttyfd, TCSETCTTY, NULL); 288 fd = open("/dev/tty", O_RDWR); 289 if (fd < 0) 290 error("%.100s: %.100s", ttyname, strerror(errno)); 291 close(*ttyfd); 292 *ttyfd = fd; 293 #else /* _UNICOS */ 294 295 /* First disconnect from the old controlling tty. */ 296 #ifdef TIOCNOTTY 297 fd = open(_PATH_TTY, O_RDWR | O_NOCTTY); 298 if (fd >= 0) { 299 (void) ioctl(fd, TIOCNOTTY, NULL); 300 close(fd); 301 } 302 #endif /* TIOCNOTTY */ 303 if (setsid() < 0) 304 error("setsid: %.100s", strerror(errno)); 305 306 /* 307 * Verify that we are successfully disconnected from the controlling 308 * tty. 309 */ 310 fd = open(_PATH_TTY, O_RDWR | O_NOCTTY); 311 if (fd >= 0) { 312 error("Failed to disconnect from controlling tty."); 313 close(fd); 314 } 315 /* Make it our controlling tty. */ 316 #ifdef TIOCSCTTY 317 debug("Setting controlling tty using TIOCSCTTY."); 318 if (ioctl(*ttyfd, TIOCSCTTY, NULL) < 0) 319 error("ioctl(TIOCSCTTY): %.100s", strerror(errno)); 320 #endif /* TIOCSCTTY */ 321 #ifdef HAVE_NEWS4 322 if (setpgrp(0,0) < 0) 323 error("SETPGRP %s",strerror(errno)); 324 #endif /* HAVE_NEWS4 */ 325 #ifdef USE_VHANGUP 326 old = mysignal(SIGHUP, SIG_IGN); 327 vhangup(); 328 mysignal(SIGHUP, old); 329 #endif /* USE_VHANGUP */ 330 fd = open(ttyname, O_RDWR); 331 if (fd < 0) { 332 error("%.100s: %.100s", ttyname, strerror(errno)); 333 } else { 334 #ifdef USE_VHANGUP 335 close(*ttyfd); 336 *ttyfd = fd; 337 #else /* USE_VHANGUP */ 338 close(fd); 339 #endif /* USE_VHANGUP */ 340 } 341 /* Verify that we now have a controlling tty. */ 342 fd = open(_PATH_TTY, O_WRONLY); 343 if (fd < 0) 344 error("open /dev/tty failed - could not set controlling tty: %.100s", 345 strerror(errno)); 346 else 347 close(fd); 348 #endif /* _UNICOS */ 349 } 350 351 /* Changes the window size associated with the pty. */ 352 353 void 354 pty_change_window_size(int ptyfd, int row, int col, 355 int xpixel, int ypixel) 356 { 357 struct winsize w; 358 359 w.ws_row = row; 360 w.ws_col = col; 361 w.ws_xpixel = xpixel; 362 w.ws_ypixel = ypixel; 363 (void) ioctl(ptyfd, TIOCSWINSZ, &w); 364 } 365 366 void 367 pty_setowner(struct passwd *pw, const char *ttyname) 368 { 369 struct group *grp; 370 gid_t gid; 371 mode_t mode; 372 struct stat st; 373 374 /* Determine the group to make the owner of the tty. */ 375 grp = getgrnam("tty"); 376 if (grp) { 377 gid = grp->gr_gid; 378 mode = S_IRUSR | S_IWUSR | S_IWGRP; 379 } else { 380 gid = pw->pw_gid; 381 mode = S_IRUSR | S_IWUSR | S_IWGRP | S_IWOTH; 382 } 383 384 /* 385 * Change owner and mode of the tty as required. 386 * Warn but continue if filesystem is read-only and the uids match/ 387 * tty is owned by root. 388 */ 389 if (stat(ttyname, &st)) 390 fatal("stat(%.100s) failed: %.100s", ttyname, 391 strerror(errno)); 392 393 if (st.st_uid != pw->pw_uid || st.st_gid != gid) { 394 if (chown(ttyname, pw->pw_uid, gid) < 0) { 395 if (errno == EROFS && 396 (st.st_uid == pw->pw_uid || st.st_uid == 0)) 397 debug("chown(%.100s, %u, %u) failed: %.100s", 398 ttyname, (u_int)pw->pw_uid, (u_int)gid, 399 strerror(errno)); 400 else 401 fatal("chown(%.100s, %u, %u) failed: %.100s", 402 ttyname, (u_int)pw->pw_uid, (u_int)gid, 403 strerror(errno)); 404 } 405 } 406 407 if ((st.st_mode & (S_IRWXU|S_IRWXG|S_IRWXO)) != mode) { 408 if (chmod(ttyname, mode) < 0) { 409 if (errno == EROFS && 410 (st.st_mode & (S_IRGRP | S_IROTH)) == 0) 411 debug("chmod(%.100s, 0%o) failed: %.100s", 412 ttyname, mode, strerror(errno)); 413 else 414 fatal("chmod(%.100s, 0%o) failed: %.100s", 415 ttyname, mode, strerror(errno)); 416 } 417 } 418 } 419