glibc/csu/elf-init.c
Ulrich Drepper 1c3c269b55 Fix startup to security-relevant statically linked binaries.
Before the change they crash on startup.  Perform IREL relocations
earlier to prevent this.
2009-11-24 11:17:06 -08:00

141 lines
4.6 KiB
C

/* Startup support for ELF initializers/finalizers in the main executable.
Copyright (C) 2002, 2003, 2004, 2005, 2009 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 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.
In addition to the permissions in the GNU Lesser General Public
License, the Free Software Foundation gives you unlimited
permission to link the compiled version of this file with other
programs, and to distribute those programs without any restriction
coming from the use of this file. (The GNU Lesser General Public
License restrictions do apply in other respects; for example, they
cover modification of the file, and distribution when not linked
into another program.)
Note that people who make modified versions of this file are not
obligated to grant this special exception for their modified
versions; it is their choice whether to do so. The GNU Lesser
General Public License gives permission to release a modified
version without this exception; this exception also makes it
possible to release a modified version which carries forward this
exception.
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, write to the Free
Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
02111-1307 USA. */
#include <stddef.h>
#if defined USE_MULTIARCH && !defined LIBC_NONSHARED
# include <link.h>
# include <dl-irel.h>
# ifdef ELF_MACHINE_IRELA
extern const ElfW(Rela) __rela_iplt_start [];
extern const ElfW(Rela) __rela_iplt_end [];
# endif
# ifdef ELF_MACHINE_IREL
extern const ElfW(Rel) __rel_iplt_start [];
extern const ElfW(Rel) __rel_iplt_end [];
# endif
#endif /* LIBC_NONSHARED */
/* These magic symbols are provided by the linker. */
extern void (*__preinit_array_start []) (int, char **, char **)
attribute_hidden;
extern void (*__preinit_array_end []) (int, char **, char **)
attribute_hidden;
extern void (*__init_array_start []) (int, char **, char **)
attribute_hidden;
extern void (*__init_array_end []) (int, char **, char **)
attribute_hidden;
extern void (*__fini_array_start []) (void) attribute_hidden;
extern void (*__fini_array_end []) (void) attribute_hidden;
/* These function symbols are provided for the .init/.fini section entry
points automagically by the linker. */
extern void _init (void);
extern void _fini (void);
/* These functions are passed to __libc_start_main by the startup code.
These get statically linked into each program. For dynamically linked
programs, this module will come from libc_nonshared.a and differs from
the libc.a module in that it doesn't call the preinit array and performs
explicit IREL{,A} relocations. */
#ifndef LIBC_NONSHARED
void
__libc_csu_irel (void)
{
# ifdef USE_MULTIARCH
# ifdef ELF_MACHINE_IRELA
{
const size_t size = __rela_iplt_end - __rela_iplt_start;
for (size_t i = 0; i < size; i++)
elf_irela (&__rela_iplt_start [i]);
}
# endif
# ifdef ELF_MACHINE_IREL
{
const size_t size = __rel_iplt_end - __rel_iplt_start;
for (size_t i = 0; i < size; i++)
elf_irel (&__rel_iplt_start [i]);
}
# endif
# endif
}
#endif
void
__libc_csu_init (int argc, char **argv, char **envp)
{
/* For dynamically linked executables the preinit array is executed by
the dynamic linker (before initializing any shared object. */
#ifndef LIBC_NONSHARED
/* For static executables, preinit happens right before init. */
{
const size_t size = __preinit_array_end - __preinit_array_start;
size_t i;
for (i = 0; i < size; i++)
(*__preinit_array_start [i]) (argc, argv, envp);
}
#endif
_init ();
const size_t size = __init_array_end - __init_array_start;
for (size_t i = 0; i < size; i++)
(*__init_array_start [i]) (argc, argv, envp);
}
/* This function should not be used anymore. We run the executable's
destructor now just like any other. We cannot remove the function,
though. */
void
__libc_csu_fini (void)
{
#ifndef LIBC_NONSHARED
size_t i = __fini_array_end - __fini_array_start;
while (i-- > 0)
(*__fini_array_start [i]) ();
_fini ();
#endif
}