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Update.
* csu/Makefile (routines): Add check_fds. * elf/rtld.c (dl_main): Call __libc_check_standard_fds for SUID binaries. Add various __builtin_expect. * sysdeps/generic/libc-start.c: Move check_fds and helper functions... * sysdeps/generic/check_fds.c: ...here. New file. * malloc/malloc.c (ptmalloc_init): Only enable debugging for SUID binaries if file /etc/suid-debug is available.
This commit is contained in:
Ulrich Drepper
parent
acb5ee2e56
commit
db33f7d4ae
@ -1,5 +1,14 @@
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2000-05-24 Ulrich Drepper <drepper@redhat.com>
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* csu/Makefile (routines): Add check_fds.
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* elf/rtld.c (dl_main): Call __libc_check_standard_fds for SUID
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binaries. Add various __builtin_expect.
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* sysdeps/generic/libc-start.c: Move check_fds and helper functions...
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* sysdeps/generic/check_fds.c: ...here. New file.
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* malloc/malloc.c (ptmalloc_init): Only enable debugging for SUID
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binaries if file /etc/suid-debug is available.
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* locale/programs/ld-collate.c (struct element_t): Add mbseqorder
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and wcseqorder members.
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(struct locale_collate_t): Likewise.
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@ -27,7 +27,7 @@
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subdir := csu
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routines = init-first libc-start $(libc-init) sysdep version
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routines = init-first libc-start $(libc-init) sysdep version check_fds
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csu-dummies = $(filter-out $(start-installed-name),crt1.o Mcrt1.o)
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extra-objs = start.o gmon-start.o \
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$(start-installed-name) g$(start-installed-name) \
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20
elf/rtld.c
20
elf/rtld.c
@ -52,6 +52,9 @@ extern void *_dl_sysdep_read_whole_file (const char *filename,
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size_t *filesize_ptr,
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int mmap_prot);
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/* Protec SUID program against misuse of file descriptors. */
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extern void __libc_check_standard_fds (void);
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/* Helper function to handle errors while resolving symbols. */
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static void print_unresolved (int errcode, const char *objname,
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const char *errsting);
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@ -396,6 +399,12 @@ dl_main (const ElfW(Phdr) *phdr,
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hp_timing_t diff;
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#endif
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/* First thing, if this is a SUID program we make sure that FDs 0,
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1, and 2 are allocated. If necessary we are doing it ourself.
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If it is not possible we stop the program. */
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if (__builtin_expect (__libc_enable_secure, 0))
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__libc_check_standard_fds ();
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/* Process the environment variable which control the behaviour. */
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process_envvars (&mode, &_dl_lazy);
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@ -673,7 +682,7 @@ of this helper program; chances are you did not intend to run this program.\n\
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preloads = NULL;
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npreloads = 0;
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if (preloadlist)
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if (__builtin_expect (preloadlist != NULL, 0))
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{
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/* The LD_PRELOAD environment variable gives list of libraries
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separated by white space or colons that are loaded before the
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@ -687,7 +696,8 @@ of this helper program; chances are you did not intend to run this program.\n\
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while ((p = strsep (&list, " :")) != NULL)
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if (p[0] != '\0'
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&& (! __libc_enable_secure || strchr (p, '/') == NULL))
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&& (__builtin_expect (! __libc_enable_secure, 1)
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|| strchr (p, '/') == NULL))
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{
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struct link_map *new_map = _dl_map_object (_dl_loaded, p, 1,
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lt_library, 0);
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@ -704,7 +714,7 @@ of this helper program; chances are you did not intend to run this program.\n\
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/* Read the contents of the file. */
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file = _dl_sysdep_read_whole_file ("/etc/ld.so.preload", &file_size,
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PROT_READ | PROT_WRITE);
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if (file)
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if (__builtin_expect (file != NULL, 0))
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{
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/* Parse the file. It contains names of libraries to be loaded,
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separated by white spaces or `:'. It may also contain
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@ -783,7 +793,7 @@ of this helper program; chances are you did not intend to run this program.\n\
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__munmap (file, file_size);
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}
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if (npreloads != 0)
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if (__builtin_expect (npreloads, 0) != 0)
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{
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/* Set up PRELOADS with a vector of the preloaded libraries. */
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struct link_map *l;
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@ -1072,7 +1082,7 @@ of this helper program; chances are you did not intend to run this program.\n\
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this has to go here because the calls it makes should use the
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rtld versions of the functions (particularly calloc()), but it
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needs to have _dl_profile_map set up by the relocator. */
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if (_dl_profile_map != NULL)
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if (__builtin_expect (_dl_profile_map != NULL, 0))
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/* We must prepare the profiling. */
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_dl_start_profile (_dl_profile_map, _dl_profile_output);
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@ -1722,7 +1722,7 @@ ptmalloc_init __MALLOC_P((void))
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__malloc_hook = save_malloc_hook;
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__free_hook = save_free_hook;
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#endif
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if(s) {
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if(s && (! __libc_enable_secure || access ("/etc/suid-debug", F_OK) == 0)) {
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if(s[0]) mALLOPt(M_CHECK_ACTION, (int)(s[0] - '0'));
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__malloc_check_init();
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}
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62
sysdeps/generic/check_fds.c
Normal file
62
sysdeps/generic/check_fds.c
Normal file
@ -0,0 +1,62 @@
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/* Copyright (C) 2000 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 Library General Public License as
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published by the Free Software Foundation; either version 2 of the
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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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Library General Public License for more details.
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You should have received a copy of the GNU Library General Public
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License along with the GNU C Library; see the file COPYING.LIB. If not,
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write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
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Boston, MA 02111-1307, USA. */
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#include <errno.h>
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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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/* 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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/* Should other OSes (e.g., Hurd) have different versions which can
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be written in a better way? */
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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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if (__builtin_expect (__libc_fcntl (fd, F_GETFD), 0) == -1
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&& errno == EBADF)
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{
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/* Something is wrong with this descriptor, it's probably not
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opened. Open /dev/null so that the SUID program we are
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about to start does not accidently use this descriptor. */
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int nullfd = __libc_open (_PATH_DEVNULL, mode);
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if (__builtin_expect (nullfd, 0) == -1)
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/* We cannot even give an error message here since it would
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run 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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void
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__libc_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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@ -16,12 +16,8 @@
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write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
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Boston, MA 02111-1307, USA. */
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#include <errno.h>
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#include <fcntl.h>
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#include <paths.h>
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#include <stdlib.h>
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#include <unistd.h>
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#include <sys/ioctl.h>
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#include <ldsodefs.h>
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extern void __libc_init_first (int argc, char **argv, char **envp);
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@ -32,7 +28,7 @@ extern int __libc_multiple_libcs;
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extern void *__libc_stack_end;
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/* Prototype for local function. */
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static void check_standard_fds (void);
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extern void __libc_check_standard_fds (void);
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int
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__libc_start_main (int (*main) (int, char **, char **), int argc,
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@ -54,10 +50,14 @@ __libc_start_main (int (*main) (int, char **, char **), int argc,
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/* Set the global _environ variable correctly. */
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__environ = &argv[argc + 1];
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#ifndef SHARED
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/* Some security at this point. Prevent starting a SUID binary where
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the standard file descriptors are not opened. */
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the standard file descriptors are not opened. We have to do this
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only for statically linked applications since otherwise the dynamic
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loader did the work already. */
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if (__builtin_expect (__libc_enable_secure, 0))
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check_standard_fds ();
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__libc_check_standard_fds ();
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#endif
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/* Register the destructor of the dynamic linker if there is any. */
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if (__builtin_expect (rtld_fini != NULL, 1))
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@ -89,32 +89,3 @@ __libc_start_main (int (*main) (int, char **, char **), int argc,
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exit ((*main) (argc, argv, __environ));
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}
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/* Should other OSes (e.g., Hurd) have different versions which can
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be written in a better way? */
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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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if (__libc_fcntl (fd, F_GETFD) == -1 && errno == EBADF)
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{
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/* Something is wrong with this descriptor, it's probably not
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opened. Open /dev/null so that the SUID program we are
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about to start does not accidently use this descriptor. */
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int nullfd = __libc_open (_PATH_DEVNULL, mode);
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if (nullfd == -1)
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/* We cannot even give an error message here since it would
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run into the same problems. */
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abort ();
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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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