mirror of
https://sourceware.org/git/glibc.git
synced 2024-12-15 23:50:13 +00:00
261 lines
6.6 KiB
C
261 lines
6.6 KiB
C
/* Copyright (C) 1998-2020 Free Software Foundation, Inc.
|
|
This file is part of the GNU C Library.
|
|
Contributed by Zack Weinberg <zack@rabi.phys.columbia.edu>, 1998.
|
|
|
|
The GNU C Library is free software; you can redistribute it and/or
|
|
modify it under the terms of the GNU Lesser General Public
|
|
License as published by the Free Software Foundation; either
|
|
version 2.1 of the License, or (at your option) any later version.
|
|
|
|
The GNU C Library is distributed in the hope that it will be useful,
|
|
but WITHOUT ANY WARRANTY; without even the implied warranty of
|
|
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
|
|
Lesser General Public License for more details.
|
|
|
|
You should have received a copy of the GNU Lesser General Public
|
|
License along with the GNU C Library; if not, see
|
|
<https://www.gnu.org/licenses/>. */
|
|
|
|
#include <assert.h>
|
|
#include <errno.h>
|
|
#include <fcntl.h>
|
|
#include <grp.h>
|
|
#include <limits.h>
|
|
#include <stdlib.h>
|
|
#include <string.h>
|
|
#include <sys/resource.h>
|
|
#include <sys/stat.h>
|
|
#include <sys/types.h>
|
|
#include <sys/wait.h>
|
|
#include <unistd.h>
|
|
|
|
#include "pty-private.h"
|
|
|
|
|
|
/* Return the result of ptsname_r in the buffer pointed to by PTS,
|
|
which should be of length BUF_LEN. If it is too long to fit in
|
|
this buffer, a sufficiently long buffer is allocated using malloc,
|
|
and returned in PTS. 0 is returned upon success, -1 otherwise. */
|
|
static int
|
|
pts_name (int fd, char **pts, size_t buf_len, struct stat64 *stp)
|
|
{
|
|
int rv;
|
|
char *buf = *pts;
|
|
|
|
for (;;)
|
|
{
|
|
char *new_buf;
|
|
|
|
if (buf_len)
|
|
{
|
|
rv = __ptsname_internal (fd, buf, buf_len, stp);
|
|
if (rv != 0)
|
|
{
|
|
if (rv == ENOTTY)
|
|
/* ptsname_r returns with ENOTTY to indicate
|
|
a descriptor not referring to a pty master.
|
|
For this condition, grantpt must return EINVAL. */
|
|
rv = EINVAL;
|
|
errno = rv; /* Not necessarily set by __ptsname_r. */
|
|
break;
|
|
}
|
|
|
|
if (memchr (buf, '\0', buf_len))
|
|
/* We succeeded and the returned name fit in the buffer. */
|
|
break;
|
|
|
|
/* Try again with a longer buffer. */
|
|
buf_len += buf_len; /* Double it */
|
|
}
|
|
else
|
|
/* No initial buffer; start out by mallocing one. */
|
|
buf_len = 128; /* First time guess. */
|
|
|
|
if (buf != *pts)
|
|
/* We've already malloced another buffer at least once. */
|
|
new_buf = (char *) realloc (buf, buf_len);
|
|
else
|
|
new_buf = (char *) malloc (buf_len);
|
|
if (! new_buf)
|
|
{
|
|
rv = -1;
|
|
__set_errno (ENOMEM);
|
|
break;
|
|
}
|
|
buf = new_buf;
|
|
}
|
|
|
|
if (rv == 0)
|
|
*pts = buf; /* Return buffer to the user. */
|
|
else if (buf != *pts)
|
|
free (buf); /* Free what we malloced when returning an error. */
|
|
|
|
return rv;
|
|
}
|
|
|
|
/* Change the ownership and access permission of the slave pseudo
|
|
terminal associated with the master pseudo terminal specified
|
|
by FD. */
|
|
int
|
|
grantpt (int fd)
|
|
{
|
|
int retval = -1;
|
|
#ifdef PATH_MAX
|
|
char _buf[PATH_MAX];
|
|
#else
|
|
char _buf[512];
|
|
#endif
|
|
char *buf = _buf;
|
|
struct stat64 st;
|
|
|
|
if (__glibc_unlikely (pts_name (fd, &buf, sizeof (_buf), &st)))
|
|
{
|
|
int save_errno = errno;
|
|
|
|
/* Check, if the file descriptor is valid. pts_name returns the
|
|
wrong errno number, so we cannot use that. */
|
|
if (__libc_fcntl (fd, F_GETFD) == -1 && errno == EBADF)
|
|
return -1;
|
|
|
|
/* If the filedescriptor is no TTY, grantpt has to set errno
|
|
to EINVAL. */
|
|
if (save_errno == ENOTTY)
|
|
__set_errno (EINVAL);
|
|
else
|
|
__set_errno (save_errno);
|
|
|
|
return -1;
|
|
}
|
|
|
|
/* Make sure that we own the device. */
|
|
uid_t uid = __getuid ();
|
|
if (st.st_uid != uid)
|
|
{
|
|
if (__chown (buf, uid, st.st_gid) < 0)
|
|
goto helper;
|
|
}
|
|
|
|
static int tty_gid = -1;
|
|
if (__glibc_unlikely (tty_gid == -1))
|
|
{
|
|
char *grtmpbuf;
|
|
struct group grbuf;
|
|
size_t grbuflen = __sysconf (_SC_GETGR_R_SIZE_MAX);
|
|
struct group *p;
|
|
|
|
/* Get the group ID of the special `tty' group. */
|
|
if (grbuflen == (size_t) -1L)
|
|
/* `sysconf' does not support _SC_GETGR_R_SIZE_MAX.
|
|
Try a moderate value. */
|
|
grbuflen = 1024;
|
|
grtmpbuf = (char *) __alloca (grbuflen);
|
|
__getgrnam_r (TTY_GROUP, &grbuf, grtmpbuf, grbuflen, &p);
|
|
if (p != NULL)
|
|
tty_gid = p->gr_gid;
|
|
}
|
|
gid_t gid = tty_gid == -1 ? __getgid () : tty_gid;
|
|
|
|
#if HAVE_PT_CHOWN
|
|
/* Make sure the group of the device is that special group. */
|
|
if (st.st_gid != gid)
|
|
{
|
|
if (__chown (buf, uid, gid) < 0)
|
|
goto helper;
|
|
}
|
|
|
|
/* Make sure the permission mode is set to readable and writable by
|
|
the owner, and writable by the group. */
|
|
mode_t mode = S_IRUSR|S_IWUSR|S_IWGRP;
|
|
#else
|
|
/* When built without pt_chown, we have delegated the creation of the
|
|
pty node with the right group and permission mode to the kernel, and
|
|
non-root users are unlikely to be able to change it. Therefore let's
|
|
consider that POSIX enforcement is the responsibility of the whole
|
|
system and not only the GNU libc. Thus accept different group or
|
|
permission mode. */
|
|
|
|
/* Make sure the permission is set to readable and writable by the
|
|
owner. For security reasons, make it writable by the group only
|
|
when originally writable and when the group of the device is that
|
|
special group. */
|
|
mode_t mode = S_IRUSR|S_IWUSR
|
|
|((st.st_gid == gid) ? (st.st_mode & S_IWGRP) : 0);
|
|
#endif
|
|
|
|
if ((st.st_mode & ACCESSPERMS) != mode)
|
|
{
|
|
if (__chmod (buf, mode) < 0)
|
|
goto helper;
|
|
}
|
|
|
|
retval = 0;
|
|
goto cleanup;
|
|
|
|
/* We have to use the helper program if it is available. */
|
|
helper:;
|
|
|
|
#if HAVE_PT_CHOWN
|
|
pid_t pid = __fork ();
|
|
if (pid == -1)
|
|
goto cleanup;
|
|
else if (pid == 0)
|
|
{
|
|
/* Disable core dumps. */
|
|
struct rlimit rl = { 0, 0 };
|
|
__setrlimit (RLIMIT_CORE, &rl);
|
|
|
|
/* We pass the master pseudo terminal as file descriptor PTY_FILENO. */
|
|
if (fd != PTY_FILENO)
|
|
if (__dup2 (fd, PTY_FILENO) < 0)
|
|
_exit (FAIL_EBADF);
|
|
|
|
# ifdef CLOSE_ALL_FDS
|
|
CLOSE_ALL_FDS ();
|
|
# endif
|
|
|
|
execle (_PATH_PT_CHOWN, __basename (_PATH_PT_CHOWN), NULL, NULL);
|
|
_exit (FAIL_EXEC);
|
|
}
|
|
else
|
|
{
|
|
int w;
|
|
|
|
if (__waitpid (pid, &w, 0) == -1)
|
|
goto cleanup;
|
|
if (!WIFEXITED (w))
|
|
__set_errno (ENOEXEC);
|
|
else
|
|
switch (WEXITSTATUS (w))
|
|
{
|
|
case 0:
|
|
retval = 0;
|
|
break;
|
|
case FAIL_EBADF:
|
|
__set_errno (EBADF);
|
|
break;
|
|
case FAIL_EINVAL:
|
|
__set_errno (EINVAL);
|
|
break;
|
|
case FAIL_EACCES:
|
|
__set_errno (EACCES);
|
|
break;
|
|
case FAIL_EXEC:
|
|
__set_errno (ENOEXEC);
|
|
break;
|
|
case FAIL_ENOMEM:
|
|
__set_errno (ENOMEM);
|
|
break;
|
|
|
|
default:
|
|
assert(! "grantpt: internal error: invalid exit code from pt_chown");
|
|
}
|
|
}
|
|
#endif
|
|
|
|
cleanup:
|
|
if (buf != _buf)
|
|
free (buf);
|
|
|
|
return retval;
|
|
}
|