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"
15RCSID("$OpenBSD: sshpty.c,v 1.1 2001/03/04 01:46:30 djm Exp $");
16RCSID("$FreeBSD: head/crypto/openssh/sshpty.c 76262 2001-05-04 04:14:23Z green $");
17
18#include <libutil.h>
19#include "sshpty.h"
20#include "log.h"
21
22/* Pty allocated with _getpty gets broken if we do I_PUSH:es to it. */
23#if defined(HAVE__GETPTY) || defined(HAVE_OPENPTY)
24#undef HAVE_DEV_PTMX
25#endif
26
27#ifndef O_NOCTTY
28#define O_NOCTTY 0
29#endif
30
31/*
32 * Allocates and opens a pty. Returns 0 if no pty could be allocated, or
33 * nonzero if a pty was successfully allocated. On success, open file
34 * descriptors for the pty and tty sides and the name of the tty side are
35 * returned (the buffer must be able to hold at least 64 characters).
36 */
37
38int
39pty_allocate(int *ptyfd, int *ttyfd, char *namebuf, int namebuflen)
40{
41#if defined(HAVE_OPENPTY) || defined(BSD4_4)
42 /* openpty(3) exists in OSF/1 and some other os'es */
43 char buf[64];
44 int i;
45
46 i = openpty(ptyfd, ttyfd, buf, NULL, NULL);
47 if (i < 0) {
48 error("openpty: %.100s", strerror(errno));
49 return 0;
50 }
51 strlcpy(namebuf, buf, namebuflen); /* possible truncation */
52 return 1;
53#else /* HAVE_OPENPTY */
54#ifdef HAVE__GETPTY
55 /*
56 * _getpty(3) exists in SGI Irix 4.x, 5.x & 6.x -- it generates more
57 * pty's automagically when needed
58 */
59 char *slave;
60
61 slave = _getpty(ptyfd, O_RDWR, 0622, 0);
62 if (slave == NULL) {
63 error("_getpty: %.100s", strerror(errno));
64 return 0;
65 }
66 strlcpy(namebuf, slave, namebuflen);
67 /* Open the slave side. */
68 *ttyfd = open(namebuf, O_RDWR | O_NOCTTY);
69 if (*ttyfd < 0) {
70 error("%.200s: %.100s", namebuf, strerror(errno));
71 close(*ptyfd);
72 return 0;
73 }
74 return 1;
75#else /* HAVE__GETPTY */
76#ifdef HAVE_DEV_PTMX
77 /*
78 * This code is used e.g. on Solaris 2.x. (Note that Solaris 2.3
79 * also has bsd-style ptys, but they simply do not work.)
80 */
81 int ptm;
82 char *pts;
83
84 ptm = open("/dev/ptmx", O_RDWR | O_NOCTTY);
85 if (ptm < 0) {
86 error("/dev/ptmx: %.100s", strerror(errno));
87 return 0;
88 }
89 if (grantpt(ptm) < 0) {
90 error("grantpt: %.100s", strerror(errno));
91 return 0;
92 }
93 if (unlockpt(ptm) < 0) {
94 error("unlockpt: %.100s", strerror(errno));
95 return 0;
96 }
97 pts = ptsname(ptm);
98 if (pts == NULL)
99 error("Slave pty side name could not be obtained.");
100 strlcpy(namebuf, pts, namebuflen);
101 *ptyfd = ptm;
102
103 /* Open the slave side. */
104 *ttyfd = open(namebuf, O_RDWR | O_NOCTTY);
105 if (*ttyfd < 0) {
106 error("%.100s: %.100s", namebuf, strerror(errno));
107 close(*ptyfd);
108 return 0;
109 }
110 /* Push the appropriate streams modules, as described in Solaris pts(7). */
111 if (ioctl(*ttyfd, I_PUSH, "ptem") < 0)
112 error("ioctl I_PUSH ptem: %.100s", strerror(errno));
113 if (ioctl(*ttyfd, I_PUSH, "ldterm") < 0)
114 error("ioctl I_PUSH ldterm: %.100s", strerror(errno));
115 if (ioctl(*ttyfd, I_PUSH, "ttcompat") < 0)
116 error("ioctl I_PUSH ttcompat: %.100s", strerror(errno));
117 return 1;
118#else /* HAVE_DEV_PTMX */
119#ifdef HAVE_DEV_PTS_AND_PTC
120 /* AIX-style pty code. */
121 const char *name;
122
123 *ptyfd = open("/dev/ptc", O_RDWR | O_NOCTTY);
124 if (*ptyfd < 0) {
125 error("Could not open /dev/ptc: %.100s", strerror(errno));
126 return 0;
127 }
128 name = ttyname(*ptyfd);
129 if (!name)
130 fatal("Open of /dev/ptc returns device for which ttyname fails.");
131 strlcpy(namebuf, name, namebuflen);
132 *ttyfd = open(name, O_RDWR | O_NOCTTY);
133 if (*ttyfd < 0) {
134 error("Could not open pty slave side %.100s: %.100s",
135 name, strerror(errno));
136 close(*ptyfd);
137 return 0;
138 }
139 return 1;
140#else /* HAVE_DEV_PTS_AND_PTC */
141 /* BSD-style pty code. */
142 char buf[64];
143 int i;
144 const char *ptymajors = "pqrstuvwxyzabcdefghijklmnoABCDEFGHIJKLMNOPQRSTUVWXYZ";
145 const char *ptyminors = "0123456789abcdef";
146 int num_minors = strlen(ptyminors);
147 int num_ptys = strlen(ptymajors) * num_minors;
148
149 for (i = 0; i < num_ptys; i++) {
150 snprintf(buf, sizeof buf, "/dev/pty%c%c", ptymajors[i / num_minors],
151 ptyminors[i % num_minors]);
152 *ptyfd = open(buf, O_RDWR | O_NOCTTY);
153 if (*ptyfd < 0)
154 continue;
155 snprintf(namebuf, namebuflen, "/dev/tty%c%c",
156 ptymajors[i / num_minors], ptyminors[i % num_minors]);
157
158 /* Open the slave side. */
159 *ttyfd = open(namebuf, O_RDWR | O_NOCTTY);
160 if (*ttyfd < 0) {
161 error("%.100s: %.100s", namebuf, strerror(errno));
162 close(*ptyfd);
163 return 0;
164 }
165 return 1;
166 }
167 return 0;
168#endif /* HAVE_DEV_PTS_AND_PTC */
169#endif /* HAVE_DEV_PTMX */
170#endif /* HAVE__GETPTY */
171#endif /* HAVE_OPENPTY */
172}
173
174/* Releases the tty. Its ownership is returned to root, and permissions to 0666. */
175
176void
177pty_release(const char *ttyname)
178{
179 if (chown(ttyname, (uid_t) 0, (gid_t) 0) < 0)
180 error("chown %.100s 0 0 failed: %.100s", ttyname, strerror(errno));
181 if (chmod(ttyname, (mode_t) 0666) < 0)
182 error("chmod %.100s 0666 failed: %.100s", ttyname, strerror(errno));
183}
184
185/* Makes the tty the processes controlling tty and sets it to sane modes. */
186
187void
188pty_make_controlling_tty(int *ttyfd, const char *ttyname)
189{
190 int fd;
191
192 /* First disconnect from the old controlling tty. */
193#ifdef TIOCNOTTY
194 fd = open(_PATH_TTY, O_RDWR | O_NOCTTY);
195 if (fd >= 0) {
196 (void) ioctl(fd, TIOCNOTTY, NULL);
197 close(fd);
198 }
199#endif /* TIOCNOTTY */
200 if (setsid() < 0)
201 error("setsid: %.100s", strerror(errno));
202
203 /*
204 * Verify that we are successfully disconnected from the controlling
205 * tty.
206 */
207 fd = open(_PATH_TTY, O_RDWR | O_NOCTTY);
208 if (fd >= 0) {
209 error("Failed to disconnect from controlling tty.");
210 close(fd);
211 }
212 /* Make it our controlling tty. */
213#ifdef TIOCSCTTY
214 debug("Setting controlling tty using TIOCSCTTY.");
215 if (ioctl(*ttyfd, TIOCSCTTY, NULL) < 0)
216 error("ioctl(TIOCSCTTY): %.100s", strerror(errno));
217#endif /* TIOCSCTTY */
218 fd = open(ttyname, O_RDWR);
219 if (fd < 0)
220 error("%.100s: %.100s", ttyname, strerror(errno));
221 else
222 close(fd);
223
224 /* Verify that we now have a controlling tty. */
225 fd = open(_PATH_TTY, O_WRONLY);
226 if (fd < 0)
227 error("open /dev/tty failed - could not set controlling tty: %.100s",
228 strerror(errno));
229 else {
230 close(fd);
231 }
232}
233
234/* Changes the window size associated with the pty. */
235
236void
237pty_change_window_size(int ptyfd, int row, int col,
238 int xpixel, int ypixel)
239{
240 struct winsize w;
241 w.ws_row = row;
242 w.ws_col = col;
243 w.ws_xpixel = xpixel;
244 w.ws_ypixel = ypixel;
245 (void) ioctl(ptyfd, TIOCSWINSZ, &w);
246}
247
248void
249pty_setowner(struct passwd *pw, const char *ttyname)
250{
251 struct group *grp;
252 gid_t gid;
253 mode_t mode;
254 struct stat st;
255
256 /* Determine the group to make the owner of the tty. */
257 grp = getgrnam("tty");
258 if (grp) {
259 gid = grp->gr_gid;
260 mode = S_IRUSR | S_IWUSR | S_IWGRP;
261 } else {
262 gid = pw->pw_gid;
263 mode = S_IRUSR | S_IWUSR | S_IWGRP | S_IWOTH;
264 }
265
266 /*
267 * Change owner and mode of the tty as required.
268 * Warn but continue if filesystem is read-only and the uids match.
269 */
270 if (stat(ttyname, &st))
271 fatal("stat(%.100s) failed: %.100s", ttyname,
272 strerror(errno));
273
274 if (st.st_uid != pw->pw_uid || st.st_gid != gid) {
275 if (chown(ttyname, pw->pw_uid, gid) < 0) {
276 if (errno == EROFS && st.st_uid == pw->pw_uid)
277 error("chown(%.100s, %d, %d) failed: %.100s",
278 ttyname, pw->pw_uid, gid,
279 strerror(errno));
280 else
281 fatal("chown(%.100s, %d, %d) failed: %.100s",
282 ttyname, pw->pw_uid, gid,
283 strerror(errno));
284 }
285 }
286
287 if ((st.st_mode & (S_IRWXU|S_IRWXG|S_IRWXO)) != mode) {
288 if (chmod(ttyname, mode) < 0) {
289 if (errno == EROFS &&
290 (st.st_mode & (S_IRGRP | S_IROTH)) == 0)
291 error("chmod(%.100s, 0%o) failed: %.100s",
292 ttyname, mode, strerror(errno));
293 else
294 fatal("chmod(%.100s, 0%o) failed: %.100s",
295 ttyname, mode, strerror(errno));
296 }
297 }
298}