mirror of
https://sourceware.org/git/glibc.git
synced 2024-12-24 11:41:07 +00:00
a828c2f533
* sysdeps/generic/libc-start.c: For SUID binaries check whether the standard file descriptors are open. Reported by Chris Evans <chris@ferret.lmh.ox.ac.uk>.
121 lines
3.6 KiB
C
121 lines
3.6 KiB
C
/* Copyright (C) 1998, 1999 Free Software Foundation, Inc.
|
|
This file is part of the GNU C Library.
|
|
|
|
The GNU C Library is free software; you can redistribute it and/or
|
|
modify it under the terms of the GNU Library General Public License as
|
|
published by the Free Software Foundation; either version 2 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
|
|
Library General Public License for more details.
|
|
|
|
You should have received a copy of the GNU Library General Public
|
|
License along with the GNU C Library; see the file COPYING.LIB. If not,
|
|
write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
|
|
Boston, MA 02111-1307, USA. */
|
|
|
|
#include <errno.h>
|
|
#include <fcntl.h>
|
|
#include <paths.h>
|
|
#include <stdlib.h>
|
|
#include <unistd.h>
|
|
#include <sys/ioctl.h>
|
|
#include <elf/ldsodefs.h>
|
|
|
|
extern void __libc_init_first (int argc, char **argv, char **envp);
|
|
|
|
extern int _dl_starting_up;
|
|
weak_extern (_dl_starting_up)
|
|
extern int __libc_multiple_libcs;
|
|
extern void *__libc_stack_end;
|
|
|
|
/* Prototype for local function. */
|
|
static void check_standard_fds (void);
|
|
|
|
int
|
|
__libc_start_main (int (*main) (int, char **, char **), int argc,
|
|
char **argv, void (*init) (void), void (*fini) (void),
|
|
void (*rtld_fini) (void), void *stack_end)
|
|
{
|
|
#ifndef PIC
|
|
/* The next variable is only here to work around a bug in gcc <= 2.7.2.2.
|
|
If the address would be taken inside the expression the optimizer
|
|
would try to be too smart and throws it away. Grrr. */
|
|
int *dummy_addr = &_dl_starting_up;
|
|
|
|
__libc_multiple_libcs = dummy_addr && !_dl_starting_up;
|
|
#endif
|
|
|
|
/* Store the lowest stack address. */
|
|
__libc_stack_end = stack_end;
|
|
|
|
/* Set the global _environ variable correctly. */
|
|
__environ = &argv[argc + 1];
|
|
|
|
/* Some security at this point. Prevent starting a SUID binary where
|
|
the standard file descriptors are not opened. */
|
|
if (__libc_enable_secure)
|
|
check_standard_fds ();
|
|
|
|
/* Register the destructor of the dynamic linker if there is any. */
|
|
if (rtld_fini != NULL)
|
|
atexit (rtld_fini);
|
|
|
|
/* Call the initializer of the libc. */
|
|
#ifdef PIC
|
|
if (_dl_debug_impcalls)
|
|
_dl_debug_message (1, "\ninitialize libc\n\n", NULL);
|
|
#endif
|
|
__libc_init_first (argc, argv, __environ);
|
|
|
|
/* Register the destructor of the program, if any. */
|
|
if (fini)
|
|
atexit (fini);
|
|
|
|
/* Call the initializer of the program, if any. */
|
|
#ifdef PIC
|
|
if (_dl_debug_impcalls)
|
|
_dl_debug_message (1, "\ninitialize program: ", argv[0], "\n\n", NULL);
|
|
#endif
|
|
if (init)
|
|
(*init) ();
|
|
|
|
#ifdef PIC
|
|
if (_dl_debug_impcalls)
|
|
_dl_debug_message (1, "\ntransferring control: ", argv[0], "\n\n", NULL);
|
|
#endif
|
|
|
|
exit ((*main) (argc, argv, __environ));
|
|
}
|
|
|
|
|
|
/* Should other OSes (e.g., Hurd) have different versions which can
|
|
be written in a better way? */
|
|
static void
|
|
check_one_fd (int fd, int mode)
|
|
{
|
|
if (__fcntl (fd, F_GETFD) == -1 && errno == EBADF)
|
|
{
|
|
/* Something is wrong with this descriptor, it's probably not
|
|
opened. Open /dev/null so that the SUID program we are
|
|
about to start does not accidently use this descriptor. */
|
|
int nullfd = __open (_PATH_DEVNULL, mode);
|
|
if (nullfd == -1)
|
|
/* We cannot even given an error message here since it would
|
|
run into the same problems. */
|
|
abort ();
|
|
}
|
|
}
|
|
|
|
|
|
static void
|
|
check_standard_fds (void)
|
|
{
|
|
/* Check all three standard file descriptors. */
|
|
check_one_fd (STDIN_FILENO, O_RDONLY);
|
|
check_one_fd (STDOUT_FILENO, O_RDWR);
|
|
check_one_fd (STDERR_FILENO, O_RDWR);
|
|
}
|