1 /* $OpenBSD: sshpty.c,v 1.24 2006/07/17 01:31:10 stevesk Exp $ */
3 * Author: Tatu Ylonen <ylo@cs.hut.fi>
4 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
6 * Allocating a pseudo-terminal, and making it the controlling tty.
8 * As far as I am concerned, the code I have written for this software
9 * can be used freely for any purpose. Any derived versions of this
10 * software must be clearly marked as such, and if the derived work is
11 * incompatible with the protocol description in the RFC file, it must be
12 * called by a name other than "ssh" or "Secure Shell".
17 #include <sys/ioctl.h>
18 #include <sys/types.h>
32 #endif /* HAVE_UTIL_H */
48 * Allocates and opens a pty. Returns 0 if no pty could be allocated, or
49 * nonzero if a pty was successfully allocated. On success, open file
50 * descriptors for the pty and tty sides and the name of the tty side are
51 * returned (the buffer must be able to hold at least 64 characters).
55 pty_allocate(int *ptyfd, int *ttyfd, char *namebuf, size_t namebuflen)
57 /* openpty(3) exists in OSF/1 and some other os'es */
61 i = openpty(ptyfd, ttyfd, NULL, NULL, NULL);
63 error("openpty: %.100s", strerror(errno));
66 name = ttyname(*ttyfd);
68 fatal("openpty returns device for which ttyname fails.");
70 strlcpy(namebuf, name, namebuflen); /* possible truncation */
74 /* Releases the tty. Its ownership is returned to root, and permissions to 0666. */
77 pty_release(const char *tty)
79 if (chown(tty, (uid_t) 0, (gid_t) 0) < 0)
80 error("chown %.100s 0 0 failed: %.100s", tty, strerror(errno));
81 if (chmod(tty, (mode_t) 0666) < 0)
82 error("chmod %.100s 0666 failed: %.100s", tty, strerror(errno));
85 /* Makes the tty the process's controlling tty and sets it to sane modes. */
88 pty_make_controlling_tty(int *ttyfd, const char *tty)
93 #endif /* USE_VHANGUP */
97 error("setsid: %.100s", strerror(errno));
99 fd = open(tty, O_RDWR|O_NOCTTY);
101 signal(SIGHUP, SIG_IGN);
102 ioctl(fd, TCVHUP, (char *)NULL);
103 signal(SIGHUP, SIG_DFL);
107 error("Failed to disconnect from controlling tty.");
110 debug("Setting controlling tty using TCSETCTTY.");
111 ioctl(*ttyfd, TCSETCTTY, NULL);
112 fd = open("/dev/tty", O_RDWR);
114 error("%.100s: %.100s", tty, strerror(errno));
119 /* First disconnect from the old controlling tty. */
121 fd = open(_PATH_TTY, O_RDWR | O_NOCTTY);
123 (void) ioctl(fd, TIOCNOTTY, NULL);
126 #endif /* TIOCNOTTY */
128 error("setsid: %.100s", strerror(errno));
131 * Verify that we are successfully disconnected from the controlling
134 fd = open(_PATH_TTY, O_RDWR | O_NOCTTY);
136 error("Failed to disconnect from controlling tty.");
139 /* Make it our controlling tty. */
141 debug("Setting controlling tty using TIOCSCTTY.");
142 if (ioctl(*ttyfd, TIOCSCTTY, NULL) < 0)
143 error("ioctl(TIOCSCTTY): %.100s", strerror(errno));
144 #endif /* TIOCSCTTY */
146 if (setpgrp(0,0) < 0)
147 error("SETPGRP %s",strerror(errno));
148 #endif /* NEED_SETPGRP */
150 old = signal(SIGHUP, SIG_IGN);
153 #endif /* USE_VHANGUP */
154 fd = open(tty, O_RDWR);
156 error("%.100s: %.100s", tty, strerror(errno));
161 #else /* USE_VHANGUP */
163 #endif /* USE_VHANGUP */
165 /* Verify that we now have a controlling tty. */
166 fd = open(_PATH_TTY, O_WRONLY);
168 error("open /dev/tty failed - could not set controlling tty: %.100s",
175 /* Changes the window size associated with the pty. */
178 pty_change_window_size(int ptyfd, u_int row, u_int col,
179 u_int xpixel, u_int ypixel)
183 /* may truncate u_int -> u_short */
186 w.ws_xpixel = xpixel;
187 w.ws_ypixel = ypixel;
188 (void) ioctl(ptyfd, TIOCSWINSZ, &w);
192 pty_setowner(struct passwd *pw, const char *tty)
199 /* Determine the group to make the owner of the tty. */
200 grp = getgrnam("tty");
203 mode = S_IRUSR | S_IWUSR | S_IWGRP;
206 mode = S_IRUSR | S_IWUSR | S_IWGRP | S_IWOTH;
210 * Change owner and mode of the tty as required.
211 * Warn but continue if filesystem is read-only and the uids match/
212 * tty is owned by root.
215 fatal("stat(%.100s) failed: %.100s", tty,
219 ssh_selinux_setup_pty(pw->pw_name, tty);
222 if (st.st_uid != pw->pw_uid || st.st_gid != gid) {
223 if (chown(tty, pw->pw_uid, gid) < 0) {
224 if (errno == EROFS &&
225 (st.st_uid == pw->pw_uid || st.st_uid == 0))
226 debug("chown(%.100s, %u, %u) failed: %.100s",
227 tty, (u_int)pw->pw_uid, (u_int)gid,
230 fatal("chown(%.100s, %u, %u) failed: %.100s",
231 tty, (u_int)pw->pw_uid, (u_int)gid,
236 if ((st.st_mode & (S_IRWXU|S_IRWXG|S_IRWXO)) != mode) {
237 if (chmod(tty, mode) < 0) {
238 if (errno == EROFS &&
239 (st.st_mode & (S_IRGRP | S_IROTH)) == 0)
240 debug("chmod(%.100s, 0%o) failed: %.100s",
241 tty, (u_int)mode, strerror(errno));
243 fatal("chmod(%.100s, 0%o) failed: %.100s",
244 tty, (u_int)mode, strerror(errno));