1 /* $OpenBSD: sshpty.c,v 1.29 2014/09/03 18:55:07 djm 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));
76 /* Android does not have a working ttyname() */
79 name = ttyname(*ttyfd);
81 fatal("openpty returns device for which ttyname fails.");
84 strlcpy(namebuf, name, namebuflen); /* possible truncation */
88 /* Releases the tty. Its ownership is returned to root, and permissions to 0666. */
91 pty_release(const char *tty)
93 #ifndef __APPLE_PRIVPTY__
94 if (chown(tty, (uid_t) 0, (gid_t) 0) < 0)
95 error("chown %.100s 0 0 failed: %.100s", tty, strerror(errno));
96 if (chmod(tty, (mode_t) 0666) < 0)
97 error("chmod %.100s 0666 failed: %.100s", tty, strerror(errno));
98 #endif /* __APPLE_PRIVPTY__ */
101 /* Makes the tty the process's controlling tty and sets it to sane modes. */
104 pty_make_controlling_tty(int *ttyfd, const char *tty)
110 error("setsid: %.100s", strerror(errno));
112 fd = open(tty, O_RDWR|O_NOCTTY);
114 signal(SIGHUP, SIG_IGN);
115 ioctl(fd, TCVHUP, (char *)NULL);
116 signal(SIGHUP, SIG_DFL);
120 error("Failed to disconnect from controlling tty.");
123 debug("Setting controlling tty using TCSETCTTY.");
124 ioctl(*ttyfd, TCSETCTTY, NULL);
125 fd = open("/dev/tty", O_RDWR);
127 error("%.100s: %.100s", tty, strerror(errno));
132 /* First disconnect from the old controlling tty. */
134 fd = open(_PATH_TTY, O_RDWR | O_NOCTTY);
136 (void) ioctl(fd, TIOCNOTTY, NULL);
139 #endif /* TIOCNOTTY */
141 error("setsid: %.100s", strerror(errno));
144 * Verify that we are successfully disconnected from the controlling
147 fd = open(_PATH_TTY, O_RDWR | O_NOCTTY);
149 error("Failed to disconnect from controlling tty.");
152 /* Make it our controlling tty. */
154 debug("Setting controlling tty using TIOCSCTTY.");
155 if (ioctl(*ttyfd, TIOCSCTTY, NULL) < 0)
156 error("ioctl(TIOCSCTTY): %.100s", strerror(errno));
157 #endif /* TIOCSCTTY */
159 if (setpgrp(0,0) < 0)
160 error("SETPGRP %s",strerror(errno));
161 #endif /* NEED_SETPGRP */
162 fd = open(tty, O_RDWR);
164 error("%.100s: %.100s", tty, strerror(errno));
168 /* Verify that we now have a controlling tty. */
169 fd = open(_PATH_TTY, O_WRONLY);
171 error("open /dev/tty failed - could not set controlling tty: %.100s",
178 /* Changes the window size associated with the pty. */
181 pty_change_window_size(int ptyfd, u_int row, u_int col,
182 u_int xpixel, u_int ypixel)
186 /* may truncate u_int -> u_short */
189 w.ws_xpixel = xpixel;
190 w.ws_ypixel = ypixel;
191 (void) ioctl(ptyfd, TIOCSWINSZ, &w);
195 pty_setowner(struct passwd *pw, const char *tty)
202 /* Determine the group to make the owner of the tty. */
203 grp = getgrnam("tty");
204 gid = (grp != NULL) ? grp->gr_gid : pw->pw_gid;
205 mode = (grp != NULL) ? 0622 : 0600;
208 * Change owner and mode of the tty as required.
209 * Warn but continue if filesystem is read-only and the uids match/
210 * tty is owned by root.
213 fatal("stat(%.100s) failed: %.100s", tty,
217 ssh_selinux_setup_pty(pw->pw_name, tty);
220 if (st.st_uid != pw->pw_uid || st.st_gid != gid) {
221 if (chown(tty, pw->pw_uid, gid) < 0) {
222 if (errno == EROFS &&
223 (st.st_uid == pw->pw_uid || st.st_uid == 0))
224 debug("chown(%.100s, %u, %u) failed: %.100s",
225 tty, (u_int)pw->pw_uid, (u_int)gid,
228 fatal("chown(%.100s, %u, %u) failed: %.100s",
229 tty, (u_int)pw->pw_uid, (u_int)gid,
234 if ((st.st_mode & (S_IRWXU|S_IRWXG|S_IRWXO)) != mode) {
235 if (chmod(tty, mode) < 0) {
236 if (errno == EROFS &&
237 (st.st_mode & (S_IRGRP | S_IROTH)) == 0)
238 debug("chmod(%.100s, 0%o) failed: %.100s",
239 tty, (u_int)mode, strerror(errno));
241 fatal("chmod(%.100s, 0%o) failed: %.100s",
242 tty, (u_int)mode, strerror(errno));