usr/src/cmd/ssh/sshd/sshpty.c

   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 1.7 2002/06/24 17:57:20 deraadt Exp $");
  16
  17 #pragma ident   "%Z%%M% %I%     %E% SMI"
  18
  19 #ifdef HAVE_UTIL_H
  20 # include <util.h>
  21 #endif /* HAVE_UTIL_H */
  22
  23 #include "sshpty.h"
  24 #include "log.h"
  25 #include "misc.h"
  26
  27 /* Pty allocated with _getpty gets broken if we do I_PUSH:es to it. */
  28 #if defined(HAVE__GETPTY) || defined(HAVE_OPENPTY)
  29 #undef HAVE_DEV_PTMX
  30 #endif
  31
  32 #ifdef HAVE_PTY_H
  33 # include <pty.h>
  34 #endif
  35 #if defined(HAVE_DEV_PTMX) && defined(HAVE_SYS_STROPTS_H)
  36 # include <sys/stropts.h>
  37 #endif
  38
  39 #ifndef O_NOCTTY
  40 #define O_NOCTTY 0
  41 #endif
  42
  43 /*
  44  * Allocates and opens a pty.  Returns 0 if no pty could be allocated, or
  45  * nonzero if a pty was successfully allocated.  On success, open file
  46  * descriptors for the pty and tty sides and the name of the tty side are
  47  * returned (the buffer must be able to hold at least 64 characters).
  48  */
  49
  50 int
  51 pty_allocate(int *ptyfd, int *ttyfd, char *namebuf, int namebuflen)
  52 {
  53 #if defined(HAVE_OPENPTY) || defined(BSD4_4)
  54         /* openpty(3) exists in OSF/1 and some other os'es */
  55         char *name;
  56         int i;
  57
  58         i = openpty(ptyfd, ttyfd, NULL, NULL, NULL);
  59         if (i < 0) {
  60                 error("openpty: %.100s", strerror(errno));
  61                 return 0;
  62         }
  63         name = ttyname(*ttyfd);
  64         if (!name)
  65                 fatal("openpty returns device for which ttyname fails.");
  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                 error("_getpty: %.100s", strerror(errno));
  80                 return 0;
  81         }
  82         strlcpy(namebuf, slave, namebuflen);
  83         /* Open the slave side. */
  84         *ttyfd = open(namebuf, O_RDWR | O_NOCTTY);
  85         if (*ttyfd < 0) {
  86                 error("%.200s: %.100s", namebuf, strerror(errno));
  87                 close(*ptyfd);
  88                 return 0;
  89         }
  90         return 1;
  91 #else /* HAVE__GETPTY */
  92 #if defined(HAVE_DEV_PTMX)
  93         /*
  94          * This code is used e.g. on Solaris 2.x.  (Note that Solaris 2.3
  95          * also has bsd-style ptys, but they simply do not work.)
  96          */
  97         int ptm;
  98         char *pts;
  99         mysig_t old_signal;
 100
 101         ptm = open("/dev/ptmx", O_RDWR | O_NOCTTY);
 102         if (ptm < 0) {
 103                 error("/dev/ptmx: %.100s", strerror(errno));
 104                 return 0;
 105         }
 106         old_signal = mysignal(SIGCHLD, SIG_DFL);
 107         if (grantpt(ptm) < 0) {
 108                 error("grantpt: %.100s", strerror(errno));
 109                 return 0;
 110         }
 111         mysignal(SIGCHLD, old_signal);
 112         if (unlockpt(ptm) < 0) {
 113                 error("unlockpt: %.100s", strerror(errno));
 114                 return 0;
 115         }
 116         pts = ptsname(ptm);
 117         if (pts == NULL)
 118                 error("Slave pty side name could not be obtained.");
 119         strlcpy(namebuf, pts, namebuflen);
 120         *ptyfd = ptm;
 121
 122         /* Open the slave side. */
 123         *ttyfd = open(namebuf, O_RDWR | O_NOCTTY);
 124         if (*ttyfd < 0) {
 125                 error("%.100s: %.100s", namebuf, strerror(errno));
 126                 close(*ptyfd);
 127                 return 0;
 128         }
 129 #ifndef HAVE_CYGWIN
 130         /*
 131          * Push the appropriate streams modules, as described in Solaris pts(7).
 132          * HP-UX pts(7) doesn't have ttcompat module.
 133          */
 134         if (ioctl(*ttyfd, I_PUSH, "ptem") < 0)
 135                 error("ioctl I_PUSH ptem: %.100s", strerror(errno));
 136         if (ioctl(*ttyfd, I_PUSH, "ldterm") < 0)
 137                 error("ioctl I_PUSH ldterm: %.100s", strerror(errno));
 138 #ifndef __hpux
 139         if (ioctl(*ttyfd, I_PUSH, "ttcompat") < 0)
 140                 error("ioctl I_PUSH ttcompat: %.100s", strerror(errno));
 141 #endif
 142 #endif
 143         return 1;
 144 #else /* HAVE_DEV_PTMX */
 145 #ifdef HAVE_DEV_PTS_AND_PTC
 146         /* AIX-style pty code. */
 147         const char *name;
 148
 149         *ptyfd = open("/dev/ptc", O_RDWR | O_NOCTTY);
 150         if (*ptyfd < 0) {
 151                 error("Could not open /dev/ptc: %.100s", strerror(errno));
 152                 return 0;
 153         }
 154         name = ttyname(*ptyfd);
 155         if (!name)
 156                 fatal("Open of /dev/ptc returns device for which ttyname fails.");
 157         strlcpy(namebuf, name, namebuflen);
 158         *ttyfd = open(name, O_RDWR | O_NOCTTY);
 159         if (*ttyfd < 0) {
 160                 error("Could not open pty slave side %.100s: %.100s",
 161                     name, strerror(errno));
 162                 close(*ptyfd);
 163                 return 0;
 164         }
 165         return 1;
 166 #else /* HAVE_DEV_PTS_AND_PTC */
 167 #ifdef _UNICOS
 168         char buf[64];
 169         int i;
 170         int highpty;
 171
 172 #ifdef _SC_CRAY_NPTY
 173         highpty = sysconf(_SC_CRAY_NPTY);
 174         if (highpty == -1)
 175                 highpty = 128;
 176 #else
 177         highpty = 128;
 178 #endif
 179
 180         for (i = 0; i < highpty; i++) {
 181                 snprintf(buf, sizeof(buf), "/dev/pty/%03d", i);
 182                 *ptyfd = open(buf, O_RDWR|O_NOCTTY);
 183                 if (*ptyfd < 0)
 184                         continue;
 185                 snprintf(namebuf, namebuflen, "/dev/ttyp%03d", i);
 186                 /* Open the slave side. */
 187                 *ttyfd = open(namebuf, O_RDWR|O_NOCTTY);
 188                 if (*ttyfd < 0) {
 189                         error("%.100s: %.100s", namebuf, strerror(errno));
 190                         close(*ptyfd);
 191                         return 0;
 192                 }
 193                 return 1;
 194         }
 195         return 0;
 196 #else
 197         /* BSD-style pty code. */
 198         char buf[64];
 199         int i;
 200         const char *ptymajors = "pqrstuvwxyzabcdefghijklmnoABCDEFGHIJKLMNOPQRSTUVWXYZ";
 201         const char *ptyminors = "0123456789abcdef";
 202         int num_minors = strlen(ptyminors);
 203         int num_ptys = strlen(ptymajors) * num_minors;
 204         struct termios tio;
 205
 206         for (i = 0; i < num_ptys; i++) {
 207                 snprintf(buf, sizeof buf, "/dev/pty%c%c", ptymajors[i / num_minors],
 208                          ptyminors[i % num_minors]);
 209                 snprintf(namebuf, namebuflen, "/dev/tty%c%c",
 210                     ptymajors[i / num_minors], ptyminors[i % num_minors]);
 211
 212                 *ptyfd = open(buf, O_RDWR | O_NOCTTY);
 213                 if (*ptyfd < 0) {
 214                         /* Try SCO style naming */
 215                         snprintf(buf, sizeof buf, "/dev/ptyp%d", i);
 216                         snprintf(namebuf, namebuflen, "/dev/ttyp%d", i);
 217                         *ptyfd = open(buf, O_RDWR | O_NOCTTY);
 218                         if (*ptyfd < 0)
 219                                 continue;
 220                 }
 221
 222                 /* Open the slave side. */
 223                 *ttyfd = open(namebuf, O_RDWR | O_NOCTTY);
 224                 if (*ttyfd < 0) {
 225                         error("%.100s: %.100s", namebuf, strerror(errno));
 226                         close(*ptyfd);
 227                         return 0;
 228                 }
 229                 /* set tty modes to a sane state for broken clients */
 230                 if (tcgetattr(*ptyfd, &tio) < 0)
 231                         log("Getting tty modes for pty failed: %.100s", strerror(errno));
 232                 else {
 233                         tio.c_lflag |= (ECHO | ISIG | ICANON);
 234                         tio.c_oflag |= (OPOST | ONLCR);
 235                         tio.c_iflag |= ICRNL;
 236
 237                         /* Set the new modes for the terminal. */
 238                         if (tcsetattr(*ptyfd, TCSANOW, &tio) < 0)
 239                                 log("Setting tty modes for pty failed: %.100s", strerror(errno));
 240                 }
 241
 242                 return 1;
 243         }
 244         return 0;
 245 #endif /* CRAY */
 246 #endif /* HAVE_DEV_PTS_AND_PTC */
 247 #endif /* HAVE_DEV_PTMX */
 248 #endif /* HAVE__GETPTY */
 249 #endif /* HAVE_OPENPTY */
 250 }
 251
 252 /* Releases the tty.  Its ownership is returned to root, and permissions to 0666. */
 253
 254 void
 255 pty_release(const char *ttyname)
 256 {
 257         if (chown(ttyname, (uid_t) 0, (gid_t) 0) < 0)
 258                 error("chown %.100s 0 0 failed: %.100s", ttyname, strerror(errno));
 259         if (chmod(ttyname, (mode_t) 0666) < 0)
 260                 error("chmod %.100s 0666 failed: %.100s", ttyname, strerror(errno));
 261 }
 262
 263 /* Makes the tty the processes controlling tty and sets it to sane modes. */
 264
 265 void
 266 pty_make_controlling_tty(int *ttyfd, const char *ttyname)
 267 {
 268         int fd;
 269 #ifdef USE_VHANGUP
 270         void *old;
 271 #endif /* USE_VHANGUP */
 272
 273 #ifdef _UNICOS
 274         if (setsid() < 0)
 275                 error("setsid: %.100s", strerror(errno));
 276
 277         fd = open(ttyname, O_RDWR|O_NOCTTY);
 278         if (fd != -1) {
 279                 mysignal(SIGHUP, SIG_IGN);
 280                 ioctl(fd, TCVHUP, (char *)NULL);
 281                 mysignal(SIGHUP, SIG_DFL);
 282                 setpgid(0, 0);
 283                 close(fd);
 284         } else {
 285                 error("Failed to disconnect from controlling tty.");
 286         }
 287
 288         debug("Setting controlling tty using TCSETCTTY.");
 289         ioctl(*ttyfd, TCSETCTTY, NULL);
 290         fd = open("/dev/tty", O_RDWR);
 291         if (fd < 0)
 292                 error("%.100s: %.100s", ttyname, strerror(errno));
 293         close(*ttyfd);
 294         *ttyfd = fd;
 295 #else /* _UNICOS */
 296
 297         /* First disconnect from the old controlling tty. */
 298 #ifdef TIOCNOTTY
 299         fd = open(_PATH_TTY, O_RDWR | O_NOCTTY);
 300         if (fd >= 0) {
 301                 (void) ioctl(fd, TIOCNOTTY, NULL);
 302                 close(fd);
 303         }
 304 #endif /* TIOCNOTTY */
 305         if (setsid() < 0)
 306                 error("setsid: %.100s", strerror(errno));
 307
 308         /*
 309          * Verify that we are successfully disconnected from the controlling
 310          * tty.
 311          */
 312         fd = open(_PATH_TTY, O_RDWR | O_NOCTTY);
 313         if (fd >= 0) {
 314                 error("Failed to disconnect from controlling tty.");
 315                 close(fd);
 316         }
 317         /* Make it our controlling tty. */
 318 #ifdef TIOCSCTTY
 319         debug("Setting controlling tty using TIOCSCTTY.");
 320         if (ioctl(*ttyfd, TIOCSCTTY, NULL) < 0)
 321                 error("ioctl(TIOCSCTTY): %.100s", strerror(errno));
 322 #endif /* TIOCSCTTY */
 323 #ifdef HAVE_NEWS4
 324         if (setpgrp(0,0) < 0)
 325                 error("SETPGRP %s",strerror(errno));
 326 #endif /* HAVE_NEWS4 */
 327 #ifdef USE_VHANGUP
 328         old = mysignal(SIGHUP, SIG_IGN);
 329         vhangup();
 330         mysignal(SIGHUP, old);
 331 #endif /* USE_VHANGUP */
 332         fd = open(ttyname, O_RDWR);
 333         if (fd < 0) {
 334                 error("%.100s: %.100s", ttyname, strerror(errno));
 335         } else {
 336 #ifdef USE_VHANGUP
 337                 close(*ttyfd);
 338                 *ttyfd = fd;
 339 #else /* USE_VHANGUP */
 340                 close(fd);
 341 #endif /* USE_VHANGUP */
 342         }
 343         /* Verify that we now have a controlling tty. */
 344         fd = open(_PATH_TTY, O_WRONLY);
 345         if (fd < 0)
 346                 error("open /dev/tty failed - could not set controlling tty: %.100s",
 347                     strerror(errno));
 348         else
 349                 close(fd);
 350 #endif /* _UNICOS */
 351 }
 352
 353 /* Changes the window size associated with the pty. */
 354
 355 void
 356 pty_change_window_size(int ptyfd, int row, int col,
 357         int xpixel, int ypixel)
 358 {
 359         struct winsize w;
 360
 361         w.ws_row = row;
 362         w.ws_col = col;
 363         w.ws_xpixel = xpixel;
 364         w.ws_ypixel = ypixel;
 365         (void) ioctl(ptyfd, TIOCSWINSZ, &w);
 366 }
 367
 368 void
 369 pty_setowner(struct passwd *pw, const char *ttyname)
 370 {
 371         struct group *grp;
 372         gid_t gid;
 373         mode_t mode;
 374         struct stat st;
 375
 376         /* Determine the group to make the owner of the tty. */
 377         grp = getgrnam("tty");
 378         if (grp) {
 379                 gid = grp->gr_gid;
 380                 mode = S_IRUSR | S_IWUSR | S_IWGRP;
 381         } else {
 382                 gid = pw->pw_gid;
 383                 mode = S_IRUSR | S_IWUSR | S_IWGRP | S_IWOTH;
 384         }
 385
 386         /*
 387          * Change owner and mode of the tty as required.
 388          * Warn but continue if filesystem is read-only and the uids match/
 389          * tty is owned by root.
 390          */
 391         if (stat(ttyname, &st))
 392                 fatal("stat(%.100s) failed: %.100s", ttyname,
 393                     strerror(errno));
 394
 395         if (st.st_uid != pw->pw_uid || st.st_gid != gid) {
 396                 if (chown(ttyname, pw->pw_uid, gid) < 0) {
 397                         if (errno == EROFS &&
 398                             (st.st_uid == pw->pw_uid || st.st_uid == 0))
 399                                 error("chown(%.100s, %u, %u) failed: %.100s",
 400                                     ttyname, (u_int)pw->pw_uid, (u_int)gid,
 401                                     strerror(errno));
 402                         else
 403                                 fatal("chown(%.100s, %u, %u) failed: %.100s",
 404                                     ttyname, (u_int)pw->pw_uid, (u_int)gid,
 405                                     strerror(errno));
 406                 }
 407         }
 408
 409         if ((st.st_mode & (S_IRWXU|S_IRWXG|S_IRWXO)) != mode) {
 410                 if (chmod(ttyname, mode) < 0) {
 411                         if (errno == EROFS &&
 412                             (st.st_mode & (S_IRGRP | S_IROTH)) == 0)
 413                                 error("chmod(%.100s, 0%o) failed: %.100s",
 414                                     ttyname, (int)mode, strerror(errno));
 415                         else
 416                                 fatal("chmod(%.100s, 0%o) failed: %.100s",
 417                                     ttyname, (int)mode, strerror(errno));
 418                 }
 419         }
 420 }