1 /* $OpenBSD: sshpty.c,v 1.28 2007/09/11 23:49:09 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/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 #ifndef __APPLE_PRIVPTY__
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__ */
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
)
105 error("setsid: %.100s", strerror(errno
));
107 fd
= open(tty
, O_RDWR
|O_NOCTTY
);
109 signal(SIGHUP
, SIG_IGN
);
110 ioctl(fd
, TCVHUP
, (char *)NULL
);
111 signal(SIGHUP
, SIG_DFL
);
115 error("Failed to disconnect from controlling tty.");
118 debug("Setting controlling tty using TCSETCTTY.");
119 ioctl(*ttyfd
, TCSETCTTY
, NULL
);
120 fd
= open("/dev/tty", O_RDWR
);
122 error("%.100s: %.100s", tty
, strerror(errno
));
127 /* First disconnect from the old controlling tty. */
129 fd
= open(_PATH_TTY
, O_RDWR
| O_NOCTTY
);
131 (void) ioctl(fd
, TIOCNOTTY
, NULL
);
134 #endif /* TIOCNOTTY */
136 error("setsid: %.100s", strerror(errno
));
139 * Verify that we are successfully disconnected from the controlling
142 fd
= open(_PATH_TTY
, O_RDWR
| O_NOCTTY
);
144 error("Failed to disconnect from controlling tty.");
147 /* Make it our controlling tty. */
149 debug("Setting controlling tty using TIOCSCTTY.");
150 if (ioctl(*ttyfd
, TIOCSCTTY
, NULL
) < 0)
151 error("ioctl(TIOCSCTTY): %.100s", strerror(errno
));
152 #endif /* TIOCSCTTY */
154 if (setpgrp(0,0) < 0)
155 error("SETPGRP %s",strerror(errno
));
156 #endif /* NEED_SETPGRP */
157 fd
= open(tty
, O_RDWR
);
159 error("%.100s: %.100s", tty
, strerror(errno
));
163 /* Verify that we now have a controlling tty. */
164 fd
= open(_PATH_TTY
, O_WRONLY
);
166 error("open /dev/tty failed - could not set controlling tty: %.100s",
173 /* Changes the window size associated with the pty. */
176 pty_change_window_size(int ptyfd
, u_int row
, u_int col
,
177 u_int xpixel
, u_int ypixel
)
181 /* may truncate u_int -> u_short */
184 w
.ws_xpixel
= xpixel
;
185 w
.ws_ypixel
= ypixel
;
186 (void) ioctl(ptyfd
, TIOCSWINSZ
, &w
);
190 pty_setowner(struct passwd
*pw
, const char *tty
)
197 /* Determine the group to make the owner of the tty. */
198 grp
= getgrnam("tty");
201 mode
= S_IRUSR
| S_IWUSR
| S_IWGRP
;
204 mode
= S_IRUSR
| S_IWUSR
| S_IWGRP
| S_IWOTH
;
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
));