1 /* $OpenBSD: sshpty.c,v 1.31 2016/11/29 03:54:50 dtucker 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/types.h>
18 #include <sys/ioctl.h>
50 # include <AvailabilityMacros.h>
51 # if (MAC_OS_X_VERSION_MAX_ALLOWED >= MAC_OS_X_VERSION_10_5)
52 # define __APPLE_PRIVPTY__
57 * Allocates and opens a pty. Returns 0 if no pty could be allocated, or
58 * nonzero if a pty was successfully allocated. On success, open file
59 * descriptors for the pty and tty sides and the name of the tty side are
60 * returned (the buffer must be able to hold at least 64 characters).
64 pty_allocate(int *ptyfd, int *ttyfd, char *namebuf, size_t namebuflen)
66 /* openpty(3) exists in OSF/1 and some other os'es */
70 i = openpty(ptyfd, ttyfd, NULL, NULL, NULL);
72 error("openpty: %.100s", strerror(errno));
75 name = ttyname(*ttyfd);
77 fatal("openpty returns device for which ttyname fails.");
79 strlcpy(namebuf, name, namebuflen); /* possible truncation */
83 /* Releases the tty. Its ownership is returned to root, and permissions to 0666. */
86 pty_release(const char *tty)
88 #if !defined(__APPLE_PRIVPTY__) && !defined(HAVE_OPENPTY)
89 if (chown(tty, (uid_t) 0, (gid_t) 0) < 0)
90 error("chown %.100s 0 0 failed: %.100s", tty, strerror(errno));
91 if (chmod(tty, (mode_t) 0666) < 0)
92 error("chmod %.100s 0666 failed: %.100s", tty, strerror(errno));
93 #endif /* !__APPLE_PRIVPTY__ && !HAVE_OPENPTY */
96 /* Makes the tty the process's controlling tty and sets it to sane modes. */
99 pty_make_controlling_tty(int *ttyfd, const char *tty)
103 /* First disconnect from the old controlling tty. */
105 fd = open(_PATH_TTY, O_RDWR | O_NOCTTY);
107 (void) ioctl(fd, TIOCNOTTY, NULL);
110 #endif /* TIOCNOTTY */
112 error("setsid: %.100s", strerror(errno));
115 * Verify that we are successfully disconnected from the controlling
118 fd = open(_PATH_TTY, O_RDWR | O_NOCTTY);
120 error("Failed to disconnect from controlling tty.");
123 /* Make it our controlling tty. */
125 debug("Setting controlling tty using TIOCSCTTY.");
126 if (ioctl(*ttyfd, TIOCSCTTY, NULL) < 0)
127 error("ioctl(TIOCSCTTY): %.100s", strerror(errno));
128 #endif /* TIOCSCTTY */
130 if (setpgrp(0,0) < 0)
131 error("SETPGRP %s",strerror(errno));
132 #endif /* NEED_SETPGRP */
133 fd = open(tty, O_RDWR);
135 error("%.100s: %.100s", tty, strerror(errno));
139 /* Verify that we now have a controlling tty. */
140 fd = open(_PATH_TTY, O_WRONLY);
142 error("open /dev/tty failed - could not set controlling tty: %.100s",
148 /* Changes the window size associated with the pty. */
151 pty_change_window_size(int ptyfd, u_int row, u_int col,
152 u_int xpixel, u_int ypixel)
156 /* may truncate u_int -> u_short */
159 w.ws_xpixel = xpixel;
160 w.ws_ypixel = ypixel;
161 (void) ioctl(ptyfd, TIOCSWINSZ, &w);
165 pty_setowner(struct passwd *pw, const char *tty)
172 /* Determine the group to make the owner of the tty. */
173 grp = getgrnam("tty");
174 gid = (grp != NULL) ? grp->gr_gid : pw->pw_gid;
175 mode = (grp != NULL) ? 0620 : 0600;
178 * Change owner and mode of the tty as required.
179 * Warn but continue if filesystem is read-only and the uids match/
180 * tty is owned by root.
183 fatal("stat(%.100s) failed: %.100s", tty,
187 ssh_selinux_setup_pty(pw->pw_name, tty);
190 if (st.st_uid != pw->pw_uid || st.st_gid != gid) {
191 if (chown(tty, pw->pw_uid, gid) < 0) {
192 if (errno == EROFS &&
193 (st.st_uid == pw->pw_uid || st.st_uid == 0))
194 debug("chown(%.100s, %u, %u) failed: %.100s",
195 tty, (u_int)pw->pw_uid, (u_int)gid,
198 fatal("chown(%.100s, %u, %u) failed: %.100s",
199 tty, (u_int)pw->pw_uid, (u_int)gid,
204 if ((st.st_mode & (S_IRWXU|S_IRWXG|S_IRWXO)) != mode) {
205 if (chmod(tty, mode) < 0) {
206 if (errno == EROFS &&
207 (st.st_mode & (S_IRGRP | S_IROTH)) == 0)
208 debug("chmod(%.100s, 0%o) failed: %.100s",
209 tty, (u_int)mode, strerror(errno));
211 fatal("chmod(%.100s, 0%o) failed: %.100s",
212 tty, (u_int)mode, strerror(errno));
217 /* Disconnect from the controlling tty. */
219 disconnect_controlling_tty(void)
224 if ((fd = open(_PATH_TTY, O_RDWR | O_NOCTTY)) >= 0) {
225 (void) ioctl(fd, TIOCNOTTY, NULL);
228 #endif /* TIOCNOTTY */