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glibc/elf/do-rel.h
Adhemerval Zanella 32612615c5 elf: Issue la_symbind for bind-now (BZ #23734) 
The audit symbind callback is not called for binaries built with
-Wl,-z,now or when LD_BIND_NOW=1 is used, nor the PLT tracking callbacks
(plt_enter and plt_exit) since this would change the expected
program semantics (where no PLT is expected) and would have performance
implications (such as for BZ#15533).

LAV_CURRENT is also bumped to indicate the audit ABI change (where
la_symbind flags are set by the loader to indicate no possible PLT
trace).

To handle powerpc64 ELFv1 function descriptor, _dl_audit_symbind
requires to know whether bind-now is used so the symbol value is
updated to function text segment instead of the OPD (for lazy binding
this is done by PPC64_LOAD_FUNCPTR on _dl_runtime_resolve).

Checked on x86_64-linux-gnu, i686-linux-gnu, aarch64-linux-gnu,
powerpc64-linux-gnu.

Reviewed-by: Carlos O'Donell <carlos@redhat.com>
Tested-by: Carlos O'Donell <carlos@redhat.com>
2022-02-01 14:49:46 -03:00

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/* Do relocations for ELF dynamic linking.
Copyright (C) 1995-2022 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/>. */
#include <ldsodefs.h>
/* This file may be included twice, to define both
`elf_dynamic_do_rel' and `elf_dynamic_do_rela'. */
#ifdef DO_RELA
# define elf_dynamic_do_Rel elf_dynamic_do_Rela
# define Rel Rela
# define elf_machine_rel elf_machine_rela
# define elf_machine_rel_relative elf_machine_rela_relative
#endif
#ifndef DO_ELF_MACHINE_REL_RELATIVE
# define DO_ELF_MACHINE_REL_RELATIVE(map, l_addr, relative) \
elf_machine_rel_relative (l_addr, relative, \
(void *) (l_addr + relative->r_offset))
#endif
/* Perform the relocations in MAP on the running program image as specified
by RELTAG, SZTAG. If LAZY is nonzero, this is the first pass on PLT
relocations; they should be set up to call _dl_runtime_resolve, rather
than fully resolved now. */
static inline void __attribute__ ((always_inline))
elf_dynamic_do_Rel (struct link_map *map, struct r_scope_elem *scope[],
ElfW(Addr) reladdr, ElfW(Addr) relsize,
__typeof (((ElfW(Dyn) *) 0)->d_un.d_val) nrelative,
int lazy, int skip_ifunc)
{
const ElfW(Rel) *r = (const void *) reladdr;
const ElfW(Rel) *end = (const void *) (reladdr + relsize);
ElfW(Addr) l_addr = map->l_addr;
# if defined ELF_MACHINE_IRELATIVE && !defined RTLD_BOOTSTRAP
const ElfW(Rel) *r2 = NULL;
const ElfW(Rel) *end2 = NULL;
# endif
#if (!defined DO_RELA || !defined ELF_MACHINE_PLT_REL) && !defined RTLD_BOOTSTRAP
/* We never bind lazily during ld.so bootstrap. Unfortunately gcc is
not clever enough to see through all the function calls to realize
that. */
if (lazy)
{
/* Doing lazy PLT relocations; they need very little info. */
for (; r < end; ++r)
# ifdef ELF_MACHINE_IRELATIVE
if (ELFW(R_TYPE) (r->r_info) == ELF_MACHINE_IRELATIVE)
{
if (r2 == NULL)
r2 = r;
end2 = r;
}
else
# endif
elf_machine_lazy_rel (map, scope, l_addr, r, skip_ifunc);
# ifdef ELF_MACHINE_IRELATIVE
if (r2 != NULL)
for (; r2 <= end2; ++r2)
if (ELFW(R_TYPE) (r2->r_info) == ELF_MACHINE_IRELATIVE)
elf_machine_lazy_rel (map, scope, l_addr, r2, skip_ifunc);
# endif
}
else
#endif
{
const ElfW(Sym) *const symtab =
(const void *) D_PTR (map, l_info[DT_SYMTAB]);
const ElfW(Rel) *relative = r;
r += nrelative;
#ifndef RTLD_BOOTSTRAP
/* This is defined in rtld.c, but nowhere in the static libc.a; make
the reference weak so static programs can still link. This
declaration cannot be done when compiling rtld.c (i.e. #ifdef
RTLD_BOOTSTRAP) because rtld.c contains the common defn for
_dl_rtld_map, which is incompatible with a weak decl in the same
file. */
# ifndef SHARED
weak_extern (GL(dl_rtld_map));
# endif
if (map != &GL(dl_rtld_map)) /* Already done in rtld itself. */
# if !defined DO_RELA || defined ELF_MACHINE_REL_RELATIVE
/* Rela platforms get the offset from r_addend and this must
be copied in the relocation address. Therefore we can skip
the relative relocations only if this is for rel
relocations or rela relocations if they are computed as
memory_loc += l_addr... */
if (l_addr != 0)
# else
/* ...or we know the object has been prelinked. */
if (l_addr != 0 || ! map->l_info[VALIDX(DT_GNU_PRELINKED)])
# endif
#endif
for (; relative < r; ++relative)
DO_ELF_MACHINE_REL_RELATIVE (map, l_addr, relative);
#ifdef RTLD_BOOTSTRAP
/* The dynamic linker always uses versioning. */
assert (map->l_info[VERSYMIDX (DT_VERSYM)] != NULL);
#else
if (map->l_info[VERSYMIDX (DT_VERSYM)])
#endif
{
const ElfW(Half) *const version =
(const void *) D_PTR (map, l_info[VERSYMIDX (DT_VERSYM)]);
for (; r < end; ++r)
{
ElfW(Half) ndx = version[ELFW(R_SYM) (r->r_info)] & 0x7fff;
const ElfW(Sym) *sym = &symtab[ELFW(R_SYM) (r->r_info)];
void *const r_addr_arg = (void *) (l_addr + r->r_offset);
const struct r_found_version *rversion = &map->l_versions[ndx];
#if defined ELF_MACHINE_IRELATIVE && !defined RTLD_BOOTSTRAP
if (ELFW(R_TYPE) (r->r_info) == ELF_MACHINE_IRELATIVE)
{
if (r2 == NULL)
r2 = r;
end2 = r;
continue;
}
#endif
elf_machine_rel (map, scope, r, sym, rversion, r_addr_arg,
skip_ifunc);
#if defined SHARED && !defined RTLD_BOOTSTRAP
if (ELFW(R_TYPE) (r->r_info) == ELF_MACHINE_JMP_SLOT
&& GLRO(dl_naudit) > 0)
{
struct link_map *sym_map
= RESOLVE_MAP (map, scope, &sym, rversion,
ELF_MACHINE_JMP_SLOT);
if (sym != NULL)
_dl_audit_symbind (map, NULL, sym, r_addr_arg, sym_map);
}
#endif
}
#if defined ELF_MACHINE_IRELATIVE && !defined RTLD_BOOTSTRAP
if (r2 != NULL)
for (; r2 <= end2; ++r2)
if (ELFW(R_TYPE) (r2->r_info) == ELF_MACHINE_IRELATIVE)
{
ElfW(Half) ndx
= version[ELFW(R_SYM) (r2->r_info)] & 0x7fff;
elf_machine_rel (map, scope, r2,
&symtab[ELFW(R_SYM) (r2->r_info)],
&map->l_versions[ndx],
(void *) (l_addr + r2->r_offset),
skip_ifunc);
}
#endif
}
#ifndef RTLD_BOOTSTRAP
else
{
for (; r < end; ++r)
{
const ElfW(Sym) *sym = &symtab[ELFW(R_SYM) (r->r_info)];
void *const r_addr_arg = (void *) (l_addr + r->r_offset);
# ifdef ELF_MACHINE_IRELATIVE
if (ELFW(R_TYPE) (r->r_info) == ELF_MACHINE_IRELATIVE)
{
if (r2 == NULL)
r2 = r;
end2 = r;
continue;
}
# endif
elf_machine_rel (map, scope, r, sym, NULL, r_addr_arg,
skip_ifunc);
# if defined SHARED && !defined RTLD_BOOTSTRAP
if (ELFW(R_TYPE) (r->r_info) == ELF_MACHINE_JMP_SLOT
&& GLRO(dl_naudit) > 0)
{
struct link_map *sym_map
= RESOLVE_MAP (map, scope, &sym,
(struct r_found_version *) NULL,
ELF_MACHINE_JMP_SLOT);
if (sym != NULL)
_dl_audit_symbind (map, NULL , sym,r_addr_arg, sym_map);
}
# endif
}
# ifdef ELF_MACHINE_IRELATIVE
if (r2 != NULL)
for (; r2 <= end2; ++r2)
if (ELFW(R_TYPE) (r2->r_info) == ELF_MACHINE_IRELATIVE)
elf_machine_rel (map, scope, r2, &symtab[ELFW(R_SYM) (r2->r_info)],
NULL, (void *) (l_addr + r2->r_offset),
skip_ifunc);
# endif
}
#endif
}
}
#undef elf_dynamic_do_Rel
#undef Rel
#undef elf_machine_rel
#undef elf_machine_rel_relative
#undef DO_ELF_MACHINE_REL_RELATIVE
#undef DO_RELA
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