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3c0ef626 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"
6a9b3198 15RCSID("$OpenBSD: sshpty.c,v 1.8 2003/02/03 08:56:16 markus Exp $");
3c0ef626 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
48int
49pty_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",
e9a17296 159 name, strerror(errno));
3c0ef626 160 close(*ptyfd);
161 return 0;
162 }
163 return 1;
164#else /* HAVE_DEV_PTS_AND_PTC */
41b2f314 165#ifdef _UNICOS
3c0ef626 166 char buf[64];
f5799ae1 167 int i;
168 int highpty;
3c0ef626 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;
700318f3 202 struct termios tio;
3c0ef626 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 }
700318f3 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
3c0ef626 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
252void
253pty_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
263void
264pty_make_controlling_tty(int *ttyfd, const char *ttyname)
265{
266 int fd;
267#ifdef USE_VHANGUP
268 void *old;
269#endif /* USE_VHANGUP */
270
41b2f314 271#ifdef _UNICOS
3c0ef626 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);
f5799ae1 292 *ttyfd = fd;
41b2f314 293#else /* _UNICOS */
3c0ef626 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",
e9a17296 345 strerror(errno));
680cee3b 346 else
3c0ef626 347 close(fd);
41b2f314 348#endif /* _UNICOS */
3c0ef626 349}
350
351/* Changes the window size associated with the pty. */
352
353void
354pty_change_window_size(int ptyfd, int row, int col,
e9a17296 355 int xpixel, int ypixel)
3c0ef626 356{
357 struct winsize w;
680cee3b 358
3c0ef626 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
366void
367pty_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) {
e9a17296 395 if (errno == EROFS &&
680cee3b 396 (st.st_uid == pw->pw_uid || st.st_uid == 0))
6a9b3198 397 debug("chown(%.100s, %u, %u) failed: %.100s",
680cee3b 398 ttyname, (u_int)pw->pw_uid, (u_int)gid,
e9a17296 399 strerror(errno));
3c0ef626 400 else
680cee3b 401 fatal("chown(%.100s, %u, %u) failed: %.100s",
402 ttyname, (u_int)pw->pw_uid, (u_int)gid,
e9a17296 403 strerror(errno));
3c0ef626 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)
6a9b3198 411 debug("chmod(%.100s, 0%o) failed: %.100s",
e9a17296 412 ttyname, mode, strerror(errno));
3c0ef626 413 else
414 fatal("chmod(%.100s, 0%o) failed: %.100s",
e9a17296 415 ttyname, mode, strerror(errno));
3c0ef626 416 }
417 }
418}
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