2 * Author: Tatu Ylonen <ylo@cs.hut.fi>
3 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
5 * Allocating a pseudo-terminal, and making it the controlling tty.
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".
15 RCSID("$OpenBSD: sshpty.c,v 1.16 2006/02/20 17:19:54 stevesk Exp $");
17 #include <sys/ioctl.h>
18 #include <sys/types.h>
27 #endif /* HAVE_UTIL_H */
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).
49 pty_allocate(int *ptyfd, int *ttyfd, char *namebuf, int namebuflen)
51 /* openpty(3) exists in OSF/1 and some other os'es */
55 i = openpty(ptyfd, ttyfd, NULL, NULL, NULL);
57 error("openpty: %.100s", strerror(errno));
60 name = ttyname(*ttyfd);
62 fatal("openpty returns device for which ttyname fails.");
64 strlcpy(namebuf, name, namebuflen); /* possible truncation */
68 /* Releases the tty. Its ownership is returned to root, and permissions to 0666. */
71 pty_release(const char *tty)
73 if (chown(tty, (uid_t) 0, (gid_t) 0) < 0)
74 error("chown %.100s 0 0 failed: %.100s", tty, strerror(errno));
75 if (chmod(tty, (mode_t) 0666) < 0)
76 error("chmod %.100s 0666 failed: %.100s", tty, strerror(errno));
79 /* Makes the tty the process's controlling tty and sets it to sane modes. */
82 pty_make_controlling_tty(int *ttyfd, const char *tty)
87 #endif /* USE_VHANGUP */
91 error("setsid: %.100s", strerror(errno));
93 fd = open(tty, O_RDWR|O_NOCTTY);
95 signal(SIGHUP, SIG_IGN);
96 ioctl(fd, TCVHUP, (char *)NULL);
97 signal(SIGHUP, SIG_DFL);
101 error("Failed to disconnect from controlling tty.");
104 debug("Setting controlling tty using TCSETCTTY.");
105 ioctl(*ttyfd, TCSETCTTY, NULL);
106 fd = open("/dev/tty", O_RDWR);
108 error("%.100s: %.100s", tty, strerror(errno));
113 /* First disconnect from the old controlling tty. */
115 fd = open(_PATH_TTY, O_RDWR | O_NOCTTY);
117 (void) ioctl(fd, TIOCNOTTY, NULL);
120 #endif /* TIOCNOTTY */
122 error("setsid: %.100s", strerror(errno));
125 * Verify that we are successfully disconnected from the controlling
128 fd = open(_PATH_TTY, O_RDWR | O_NOCTTY);
130 error("Failed to disconnect from controlling tty.");
133 /* Make it our controlling tty. */
135 debug("Setting controlling tty using TIOCSCTTY.");
136 if (ioctl(*ttyfd, TIOCSCTTY, NULL) < 0)
137 error("ioctl(TIOCSCTTY): %.100s", strerror(errno));
138 #endif /* TIOCSCTTY */
140 if (setpgrp(0,0) < 0)
141 error("SETPGRP %s",strerror(errno));
142 #endif /* NEED_SETPGRP */
144 old = signal(SIGHUP, SIG_IGN);
147 #endif /* USE_VHANGUP */
148 fd = open(tty, O_RDWR);
150 error("%.100s: %.100s", tty, strerror(errno));
155 #else /* USE_VHANGUP */
157 #endif /* USE_VHANGUP */
159 /* Verify that we now have a controlling tty. */
160 fd = open(_PATH_TTY, O_WRONLY);
162 error("open /dev/tty failed - could not set controlling tty: %.100s",
169 /* Changes the window size associated with the pty. */
172 pty_change_window_size(int ptyfd, int row, int col,
173 int xpixel, int ypixel)
179 w.ws_xpixel = xpixel;
180 w.ws_ypixel = ypixel;
181 (void) ioctl(ptyfd, TIOCSWINSZ, &w);
185 pty_setowner(struct passwd *pw, const char *tty)
192 /* Determine the group to make the owner of the tty. */
193 grp = getgrnam("tty");
196 mode = S_IRUSR | S_IWUSR | S_IWGRP;
199 mode = S_IRUSR | S_IWUSR | S_IWGRP | S_IWOTH;
203 * Change owner and mode of the tty as required.
204 * Warn but continue if filesystem is read-only and the uids match/
205 * tty is owned by root.
208 fatal("stat(%.100s) failed: %.100s", tty,
211 if (st.st_uid != pw->pw_uid || st.st_gid != gid) {
212 if (chown(tty, pw->pw_uid, gid) < 0) {
213 if (errno == EROFS &&
214 (st.st_uid == pw->pw_uid || st.st_uid == 0))
215 debug("chown(%.100s, %u, %u) failed: %.100s",
216 tty, (u_int)pw->pw_uid, (u_int)gid,
219 fatal("chown(%.100s, %u, %u) failed: %.100s",
220 tty, (u_int)pw->pw_uid, (u_int)gid,
225 if ((st.st_mode & (S_IRWXU|S_IRWXG|S_IRWXO)) != mode) {
226 if (chmod(tty, mode) < 0) {
227 if (errno == EROFS &&
228 (st.st_mode & (S_IRGRP | S_IROTH)) == 0)
229 debug("chmod(%.100s, 0%o) failed: %.100s",
230 tty, (u_int)mode, strerror(errno));
232 fatal("chmod(%.100s, 0%o) failed: %.100s",
233 tty, (u_int)mode, strerror(errno));