glibc/elf/dl-support.c
Paul Pluzhnikov 630da022cb Fix misspellings in elf/ -- BZ 25337
Applying this commit results in bit-identical libc.so.6.
The elf/ld-linux-x86-64.so.2 does change, but only in .note.gnu.build-id

Reviewed-by: Carlos O'Donell <carlos@redhat.com>
2023-05-29 23:00:12 +00:00

374 lines
11 KiB
C

/* Support for dynamic linking code in static libc.
Copyright (C) 1996-2023 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.
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/>. */
/* This file defines some things that for the dynamic linker are defined in
rtld.c and dl-sysdep.c in ways appropriate to bootstrap dynamic linking. */
#include <string.h>
/* Mark symbols hidden in static PIE for early self relocation to work.
Note: string.h may have ifuncs which cannot be hidden on i686. */
#if BUILD_PIE_DEFAULT
# pragma GCC visibility push(hidden)
#endif
#include <errno.h>
#include <libintl.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/param.h>
#include <stdint.h>
#include <ldsodefs.h>
#include <dl-machine.h>
#include <libc-lock.h>
#include <dl-cache.h>
#include <dl-procinfo.h>
#include <unsecvars.h>
#include <hp-timing.h>
#include <stackinfo.h>
#include <dl-vdso.h>
#include <dl-vdso-setup.h>
#include <dl-auxv.h>
#include <dl-find_object.h>
#include <array_length.h>
#include <dl-symbol-redir-ifunc.h>
extern char *__progname;
char **_dl_argv = &__progname; /* This is checked for some error messages. */
/* Name of the architecture. */
const char *_dl_platform;
size_t _dl_platformlen;
int _dl_debug_mask;
int _dl_lazy;
int _dl_dynamic_weak;
/* If nonzero print warnings about problematic situations. */
int _dl_verbose;
/* We never do profiling. */
const char *_dl_profile;
const char *_dl_profile_output;
/* Names of shared object for which the RUNPATHs and RPATHs should be
ignored. */
const char *_dl_inhibit_rpath;
/* The map for the object we will profile. */
struct link_map *_dl_profile_map;
/* This is the address of the last stack address ever used. */
void *__libc_stack_end;
/* Path where the binary is found. */
const char *_dl_origin_path;
/* Nonzero if runtime lookup should not update the .got/.plt. */
int _dl_bind_not;
/* A dummy link map for the executable, used by dlopen to access the global
scope. We don't export any symbols ourselves, so this can be minimal. */
static struct link_map _dl_main_map =
{
.l_name = (char *) "",
.l_real = &_dl_main_map,
.l_ns = LM_ID_BASE,
.l_libname = &(struct libname_list) { .name = "", .dont_free = 1 },
.l_searchlist =
{
.r_list = &(struct link_map *) { &_dl_main_map },
.r_nlist = 1,
},
.l_symbolic_searchlist = { .r_list = &(struct link_map *) { NULL } },
.l_type = lt_executable,
.l_scope_mem = { &_dl_main_map.l_searchlist },
.l_scope_max = (sizeof (_dl_main_map.l_scope_mem)
/ sizeof (_dl_main_map.l_scope_mem[0])),
.l_scope = _dl_main_map.l_scope_mem,
.l_local_scope = { &_dl_main_map.l_searchlist },
.l_used = 1,
.l_tls_offset = NO_TLS_OFFSET,
.l_serial = 1,
};
/* Namespace information. */
struct link_namespaces _dl_ns[DL_NNS] =
{
[LM_ID_BASE] =
{
._ns_loaded = &_dl_main_map,
._ns_nloaded = 1,
._ns_main_searchlist = &_dl_main_map.l_searchlist,
}
};
size_t _dl_nns = 1;
/* Incremented whenever something may have been added to dl_loaded. */
unsigned long long _dl_load_adds = 1;
/* Fake scope of the main application. */
struct r_scope_elem _dl_initial_searchlist =
{
.r_list = &(struct link_map *) { &_dl_main_map },
.r_nlist = 1,
};
#ifndef HAVE_INLINED_SYSCALLS
/* Nonzero during startup. */
int _dl_starting_up = 1;
#endif
/* Random data provided by the kernel. */
void *_dl_random;
/* Get architecture specific initializer. */
#include <dl-procruntime.c>
#include <dl-procinfo.c>
size_t _dl_pagesize = EXEC_PAGESIZE;
size_t _dl_minsigstacksize = CONSTANT_MINSIGSTKSZ;
int _dl_inhibit_cache;
/* All known directories in sorted order. */
struct r_search_path_elem *_dl_all_dirs;
/* All directories after startup. */
struct r_search_path_elem *_dl_init_all_dirs;
/* The object to be initialized first. */
struct link_map *_dl_initfirst;
/* Descriptor to write debug messages to. */
int _dl_debug_fd = STDERR_FILENO;
ElfW(auxv_t) *_dl_auxv;
const ElfW(Phdr) *_dl_phdr;
size_t _dl_phnum;
uint64_t _dl_hwcap;
uint64_t _dl_hwcap2;
enum dso_sort_algorithm _dl_dso_sort_algo;
/* The value of the FPU control word the kernel will preset in hardware. */
fpu_control_t _dl_fpu_control = _FPU_DEFAULT;
/* Prevailing state of the stack. Generally this includes PF_X, indicating it's
* executable but this isn't true for all platforms. */
ElfW(Word) _dl_stack_flags = DEFAULT_STACK_PERMS;
#if PTHREAD_IN_LIBC
list_t _dl_stack_used;
list_t _dl_stack_user;
list_t _dl_stack_cache;
size_t _dl_stack_cache_actsize;
uintptr_t _dl_in_flight_stack;
int _dl_stack_cache_lock;
#else
/* If loading a shared object requires that we make the stack executable
when it was not, we do it by calling this function.
It returns an errno code or zero on success. */
int (*_dl_make_stack_executable_hook) (void **) = _dl_make_stack_executable;
void (*_dl_init_static_tls) (struct link_map *) = &_dl_nothread_init_static_tls;
#endif
struct dl_scope_free_list *_dl_scope_free_list;
#ifdef NEED_DL_SYSINFO
/* Needed for improved syscall handling on at least x86/Linux. NB: Don't
initialize it here to avoid RELATIVE relocation in static PIE. */
uintptr_t _dl_sysinfo;
#endif
#ifdef NEED_DL_SYSINFO_DSO
/* Address of the ELF headers in the vsyscall page. */
const ElfW(Ehdr) *_dl_sysinfo_dso;
struct link_map *_dl_sysinfo_map;
# include "get-dynamic-info.h"
#endif
#include "setup-vdso.h"
/* Define the vDSO function pointers. */
#include <dl-vdso-setup.c>
/* During the program run we must not modify the global data of
loaded shared object simultaneously in two threads. Therefore we
protect `_dl_open' and `_dl_close' in dl-close.c.
This must be a recursive lock since the initializer function of
the loaded object might as well require a call to this function.
At this time it is not anymore a problem to modify the tables. */
__rtld_lock_define_initialized_recursive (, _dl_load_lock)
/* This lock is used to keep __dl_iterate_phdr from inspecting the
list of loaded objects while an object is added to or removed from
that list. */
__rtld_lock_define_initialized_recursive (, _dl_load_write_lock)
/* This lock protects global and module specific TLS related data.
E.g. it is held in dlopen and dlclose when GL(dl_tls_generation),
GL(dl_tls_max_dtv_idx) or GL(dl_tls_dtv_slotinfo_list) are
accessed and when TLS related relocations are processed for a
module. It was introduced to keep pthread_create accessing TLS
state that is being set up. */
__rtld_lock_define_initialized_recursive (, _dl_load_tls_lock)
#ifdef HAVE_AUX_VECTOR
#include <dl-parse_auxv.h>
int _dl_clktck;
void
_dl_aux_init (ElfW(auxv_t) *av)
{
#ifdef NEED_DL_SYSINFO
/* NB: Avoid RELATIVE relocation in static PIE. */
GL(dl_sysinfo) = DL_SYSINFO_DEFAULT;
#endif
_dl_auxv = av;
dl_parse_auxv_t auxv_values;
/* Use an explicit initialization loop here because memset may not
be available yet. */
for (int i = 0; i < array_length (auxv_values); ++i)
auxv_values[i] = 0;
_dl_parse_auxv (av, auxv_values);
_dl_phdr = (void*) auxv_values[AT_PHDR];
_dl_phnum = auxv_values[AT_PHNUM];
if (_dl_phdr == NULL)
{
/* Starting from binutils-2.23, the linker will define the
magic symbol __ehdr_start to point to our own ELF header
if it is visible in a segment that also includes the phdrs.
So we can set up _dl_phdr and _dl_phnum even without any
information from auxv. */
extern const ElfW(Ehdr) __ehdr_start attribute_hidden;
assert (__ehdr_start.e_phentsize == sizeof *GL(dl_phdr));
_dl_phdr = (const void *) &__ehdr_start + __ehdr_start.e_phoff;
_dl_phnum = __ehdr_start.e_phnum;
}
assert (_dl_phdr != NULL);
}
#endif
void
_dl_non_dynamic_init (void)
{
_dl_main_map.l_origin = _dl_get_origin ();
_dl_main_map.l_phdr = GL(dl_phdr);
_dl_main_map.l_phnum = GL(dl_phnum);
_dl_verbose = *(getenv ("LD_WARN") ?: "") == '\0' ? 0 : 1;
/* Set up the data structures for the system-supplied DSO early,
so they can influence _dl_init_paths. */
setup_vdso (NULL, NULL);
/* With vDSO setup we can initialize the function pointers. */
setup_vdso_pointers ();
/* Initialize the data structures for the search paths for shared
objects. */
_dl_init_paths (getenv ("LD_LIBRARY_PATH"), "LD_LIBRARY_PATH",
/* No glibc-hwcaps selection support in statically
linked binaries. */
NULL, NULL);
/* Remember the last search directory added at startup. */
_dl_init_all_dirs = GL(dl_all_dirs);
_dl_lazy = *(getenv ("LD_BIND_NOW") ?: "") == '\0';
_dl_bind_not = *(getenv ("LD_BIND_NOT") ?: "") != '\0';
_dl_dynamic_weak = *(getenv ("LD_DYNAMIC_WEAK") ?: "") == '\0';
_dl_profile_output = getenv ("LD_PROFILE_OUTPUT");
if (_dl_profile_output == NULL || _dl_profile_output[0] == '\0')
_dl_profile_output
= &"/var/tmp\0/var/profile"[__libc_enable_secure ? 9 : 0];
if (__libc_enable_secure)
{
static const char unsecure_envvars[] =
UNSECURE_ENVVARS
;
const char *cp = unsecure_envvars;
while (cp < unsecure_envvars + sizeof (unsecure_envvars))
{
__unsetenv (cp);
cp = strchr (cp, '\0') + 1;
}
}
#ifdef DL_PLATFORM_INIT
DL_PLATFORM_INIT;
#endif
/* Now determine the length of the platform string. */
if (_dl_platform != NULL)
_dl_platformlen = strlen (_dl_platform);
for (const ElfW(Phdr) *ph = _dl_phdr; ph < &_dl_phdr[_dl_phnum]; ++ph)
switch (ph->p_type)
{
/* Check if the stack is nonexecutable. */
case PT_GNU_STACK:
_dl_stack_flags = ph->p_flags;
break;
case PT_GNU_RELRO:
_dl_main_map.l_relro_addr = ph->p_vaddr;
_dl_main_map.l_relro_size = ph->p_memsz;
break;
}
call_function_static_weak (_dl_find_object_init);
/* Setup relro on the binary itself. */
if (_dl_main_map.l_relro_size != 0)
_dl_protect_relro (&_dl_main_map);
}
#ifdef DL_SYSINFO_IMPLEMENTATION
DL_SYSINFO_IMPLEMENTATION
#endif
#if ENABLE_STATIC_PIE
/* Since relocation to hidden _dl_main_map causes relocation overflow on
aarch64, a function is used to get the address of _dl_main_map. */
struct link_map *
_dl_get_dl_main_map (void)
{
return &_dl_main_map;
}
#endif
/* This is used by _dl_runtime_profile, not used on static code. */
void
DL_ARCH_FIXUP_ATTRIBUTE
_dl_audit_pltexit (struct link_map *l, ElfW(Word) reloc_arg,
const void *inregs, void *outregs)
{
}