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openssh/pty.c

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/*
* Author: Tatu Ylonen <ylo@cs.hut.fi>
* Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
* All rights reserved
* Allocating a pseudo-terminal, and making it the controlling tty.
*
* As far as I am concerned, the code I have written for this software
* can be used freely for any purpose. Any derived versions of this
* software must be clearly marked as such, and if the derived work is
* incompatible with the protocol description in the RFC file, it must be
* called by a name other than "ssh" or "Secure Shell".
*/
#include "includes.h"
RCSID("$OpenBSD: pty.c,v 1.16 2000/09/07 21:13:37 markus Exp $");
#ifdef HAVE_UTIL_H
# include <util.h>
#endif /* HAVE_UTIL_H */
#include "pty.h"
#include "ssh.h"
/* Pty allocated with _getpty gets broken if we do I_PUSH:es to it. */
#if defined(HAVE__GETPTY) || defined(HAVE_OPENPTY)
#undef HAVE_DEV_PTMX
#endif
#ifdef HAVE_PTY_H
# include <pty.h>
#endif
#if defined(HAVE_DEV_PTMX) && defined(HAVE_SYS_STROPTS_H)
# include <sys/stropts.h>
#endif
#ifndef O_NOCTTY
#define O_NOCTTY 0
#endif
/*
* Allocates and opens a pty. Returns 0 if no pty could be allocated, or
* nonzero if a pty was successfully allocated. On success, open file
* descriptors for the pty and tty sides and the name of the tty side are
* returned (the buffer must be able to hold at least 64 characters).
*/
int
pty_allocate(int *ptyfd, int *ttyfd, char *namebuf, int namebuflen)
{
#if defined(HAVE_OPENPTY) || defined(BSD4_4)
/* openpty(3) exists in OSF/1 and some other os'es */
char buf[64];
int i;
i = openpty(ptyfd, ttyfd, buf, NULL, NULL);
if (i < 0) {
error("openpty: %.100s", strerror(errno));
return 0;
}
strlcpy(namebuf, buf, namebuflen); /* possible truncation */
return 1;
#else /* HAVE_OPENPTY */
#ifdef HAVE__GETPTY
/*
* _getpty(3) exists in SGI Irix 4.x, 5.x & 6.x -- it generates more
* pty's automagically when needed
*/
char *slave;
slave = _getpty(ptyfd, O_RDWR, 0622, 0);
if (slave == NULL) {
error("_getpty: %.100s", strerror(errno));
return 0;
}
strlcpy(namebuf, slave, namebuflen);
/* Open the slave side. */
*ttyfd = open(namebuf, O_RDWR | O_NOCTTY);
if (*ttyfd < 0) {
error("%.200s: %.100s", namebuf, strerror(errno));
close(*ptyfd);
return 0;
}
return 1;
#else /* HAVE__GETPTY */
#if defined(HAVE_DEV_PTMX)
/*
* This code is used e.g. on Solaris 2.x. (Note that Solaris 2.3
* also has bsd-style ptys, but they simply do not work.)
*/
int ptm;
char *pts;
ptm = open("/dev/ptmx", O_RDWR | O_NOCTTY);
if (ptm < 0) {
error("/dev/ptmx: %.100s", strerror(errno));
return 0;
}
if (grantpt(ptm) < 0) {
error("grantpt: %.100s", strerror(errno));
return 0;
}
if (unlockpt(ptm) < 0) {
error("unlockpt: %.100s", strerror(errno));
return 0;
}
pts = ptsname(ptm);
if (pts == NULL)
error("Slave pty side name could not be obtained.");
strlcpy(namebuf, pts, namebuflen);
*ptyfd = ptm;
/* Open the slave side. */
*ttyfd = open(namebuf, O_RDWR | O_NOCTTY);
if (*ttyfd < 0) {
error("%.100s: %.100s", namebuf, strerror(errno));
close(*ptyfd);
return 0;
}
#ifndef HAVE_CYGWIN
/*
* Push the appropriate streams modules, as described in Solaris pts(7).
* HP-UX pts(7) doesn't have ttcompat module.
*/
if (ioctl(*ttyfd, I_PUSH, "ptem") < 0)
error("ioctl I_PUSH ptem: %.100s", strerror(errno));
if (ioctl(*ttyfd, I_PUSH, "ldterm") < 0)
error("ioctl I_PUSH ldterm: %.100s", strerror(errno));
#ifndef __hpux
if (ioctl(*ttyfd, I_PUSH, "ttcompat") < 0)
error("ioctl I_PUSH ttcompat: %.100s", strerror(errno));
#endif
#endif
return 1;
#else /* HAVE_DEV_PTMX */
#ifdef HAVE_DEV_PTS_AND_PTC
/* AIX-style pty code. */
const char *name;
*ptyfd = open("/dev/ptc", O_RDWR | O_NOCTTY);
if (*ptyfd < 0) {
error("Could not open /dev/ptc: %.100s", strerror(errno));
return 0;
}
name = ttyname(*ptyfd);
if (!name)
fatal("Open of /dev/ptc returns device for which ttyname fails.");
strlcpy(namebuf, name, namebuflen);
*ttyfd = open(name, O_RDWR | O_NOCTTY);
if (*ttyfd < 0) {
error("Could not open pty slave side %.100s: %.100s",
name, strerror(errno));
close(*ptyfd);
return 0;
}
return 1;
#else /* HAVE_DEV_PTS_AND_PTC */
/* BSD-style pty code. */
char buf[64];
int i;
const char *ptymajors = "pqrstuvwxyzabcdefghijklmnoABCDEFGHIJKLMNOPQRSTUVWXYZ";
const char *ptyminors = "0123456789abcdef";
int num_minors = strlen(ptyminors);
int num_ptys = strlen(ptymajors) * num_minors;
for (i = 0; i < num_ptys; i++) {
snprintf(buf, sizeof buf, "/dev/pty%c%c", ptymajors[i / num_minors],
ptyminors[i % num_minors]);
snprintf(namebuf, namebuflen, "/dev/tty%c%c",
ptymajors[i / num_minors], ptyminors[i % num_minors]);
*ptyfd = open(buf, O_RDWR | O_NOCTTY);
if (*ptyfd < 0) {
/* Try SCO style naming */
snprintf(buf, sizeof buf, "/dev/ptyp%d", i);
snprintf(namebuf, namebuflen, "/dev/ttyp%d", i);
*ptyfd = open(buf, O_RDWR | O_NOCTTY);
if (*ptyfd < 0)
continue;
}
/* Open the slave side. */
*ttyfd = open(namebuf, O_RDWR | O_NOCTTY);
if (*ttyfd < 0) {
error("%.100s: %.100s", namebuf, strerror(errno));
close(*ptyfd);
return 0;
}
return 1;
}
return 0;
#endif /* HAVE_DEV_PTS_AND_PTC */
#endif /* HAVE_DEV_PTMX */
#endif /* HAVE__GETPTY */
#endif /* HAVE_OPENPTY */
}
/* Releases the tty. Its ownership is returned to root, and permissions to 0666. */
void
pty_release(const char *ttyname)
{
if (chown(ttyname, (uid_t) 0, (gid_t) 0) < 0)
error("chown %.100s 0 0 failed: %.100s", ttyname, strerror(errno));
if (chmod(ttyname, (mode_t) 0666) < 0)
error("chmod %.100s 0666 failed: %.100s", ttyname, strerror(errno));
}
/* Makes the tty the processes controlling tty and sets it to sane modes. */
void
pty_make_controlling_tty(int *ttyfd, const char *ttyname)
{
int fd;
#ifdef USE_VHANGUP
void *old;
#endif /* USE_VHANGUP */
/* First disconnect from the old controlling tty. */
#ifdef TIOCNOTTY
fd = open("/dev/tty", O_RDWR | O_NOCTTY);
if (fd >= 0) {
(void) ioctl(fd, TIOCNOTTY, NULL);
close(fd);
}
#endif /* TIOCNOTTY */
if (setsid() < 0)
error("setsid: %.100s", strerror(errno));
/*
* Verify that we are successfully disconnected from the controlling
* tty.
*/
fd = open("/dev/tty", O_RDWR | O_NOCTTY);
if (fd >= 0) {
error("Failed to disconnect from controlling tty.");
close(fd);
}
/* Make it our controlling tty. */
#ifdef TIOCSCTTY
debug("Setting controlling tty using TIOCSCTTY.");
/*
* We ignore errors from this, because HPSUX defines TIOCSCTTY, but
* returns EINVAL with these arguments, and there is absolutely no
* documentation.
*/
ioctl(*ttyfd, TIOCSCTTY, NULL);
#endif /* TIOCSCTTY */
#ifdef HAVE_NEWS4
if (setpgrp(0,0) < 0)
error("SETPGRP %s",strerror(errno));
#endif /* HAVE_NEWS4 */
#ifdef USE_VHANGUP
old = signal(SIGHUP, SIG_IGN);
vhangup();
signal(SIGHUP, old);
#endif /* USE_VHANGUP */
fd = open(ttyname, O_RDWR);
if (fd < 0) {
error("%.100s: %.100s", ttyname, strerror(errno));
} else {
#ifdef USE_VHANGUP
close(*ttyfd);
*ttyfd = fd;
#else /* USE_VHANGUP */
close(fd);
#endif /* USE_VHANGUP */
}
/* Verify that we now have a controlling tty. */
fd = open("/dev/tty", O_WRONLY);
if (fd < 0)
error("open /dev/tty failed - could not set controlling tty: %.100s",
strerror(errno));
else {
close(fd);
}
}
/* Changes the window size associated with the pty. */
void
pty_change_window_size(int ptyfd, int row, int col,
int xpixel, int ypixel)
{
struct winsize w;
w.ws_row = row;
w.ws_col = col;
w.ws_xpixel = xpixel;
w.ws_ypixel = ypixel;
(void) ioctl(ptyfd, TIOCSWINSZ, &w);
}
void
pty_setowner(struct passwd *pw, const char *ttyname)
{
struct group *grp;
gid_t gid;
mode_t mode;
/* Determine the group to make the owner of the tty. */
grp = getgrnam("tty");
if (grp) {
gid = grp->gr_gid;
mode = S_IRUSR | S_IWUSR | S_IWGRP;
} else {
gid = pw->pw_gid;
mode = S_IRUSR | S_IWUSR | S_IWGRP | S_IWOTH;
}
/* Change ownership of the tty. */
if (chown(ttyname, pw->pw_uid, gid) < 0)
fatal("chown(%.100s, %d, %d) failed: %.100s",
ttyname, pw->pw_uid, gid, strerror(errno));
if (chmod(ttyname, mode) < 0)
fatal("chmod(%.100s, 0%o) failed: %.100s",
ttyname, mode, strerror(errno));
}
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