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106 lines
3.0 KiB
C
106 lines
3.0 KiB
C
/* Copyright (C) 2000-2023 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; if not, see
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<https://www.gnu.org/licenses/>. */
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#include <fcntl.h>
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#include <paths.h>
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#include <unistd.h>
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#include <hurd.h>
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#include <hurd/fd.h>
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#include <set-hooks.h>
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/* Try to get a machine dependent instruction which will make the
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program crash. This is used in case everything else fails. */
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#include <abort-instr.h>
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#ifndef ABORT_INSTRUCTION
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/* No such instruction is available. */
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# define ABORT_INSTRUCTION
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#endif
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static void
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check_one_fd (int fd, int mode)
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{
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struct hurd_fd *d;
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d = _hurd_fd_get (fd);
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if (d == NULL)
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{
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/* This descriptor hasn't been opened. We try to allocate the
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descriptor and open /dev/null on it so that the SUID program
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we are about to start does not accidentally use this
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descriptor. */
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d = _hurd_alloc_fd (NULL, fd);
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if (d != NULL)
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{
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mach_port_t port;
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port = __file_name_lookup (_PATH_DEVNULL, mode, 0);
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if (port)
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{
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/* Since /dev/null isn't supposed to be a terminal, we
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avoid any ctty magic. */
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d->port.port = port;
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d->flags = 0;
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__spin_unlock (&d->port.lock);
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return;
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}
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}
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/* We cannot even give an error message here since it would run
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into the same problems. */
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while (1)
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/* Try for ever and ever. */
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ABORT_INSTRUCTION;
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}
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}
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static void
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check_standard_fds (void)
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{
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/* Check all three standard file descriptors. */
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check_one_fd (STDIN_FILENO, O_RDONLY);
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check_one_fd (STDOUT_FILENO, O_RDWR);
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check_one_fd (STDERR_FILENO, O_RDWR);
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}
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static void attribute_used_retain
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init_standard_fds (void)
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{
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/* Now that we have FDs, make sure that, if this is a SUID program,
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FDs 0, 1 and 2 are allocated. If necessary we'll set them up
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ourselves. If that's not possible we stop the program. */
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if (__builtin_expect (__libc_enable_secure, 0))
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check_standard_fds ();
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}
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SET_RELHOOK (_hurd_fd_subinit, init_standard_fds);
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#ifndef SHARED
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void
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__libc_check_standard_fds (void)
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{
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/* We don't check the standard file descriptors here. They will be
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checked when we initialize the file descriptor table, as part of
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the _hurd_fd_subinit hook.
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This function is only present to make sure that this module gets
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linked in when part of the static libc. */
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}
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#endif
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