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df94b6412e
global scope, wait for all lookups to finish afterwards. * elf/dl-open.c (add_to_global): When global scope array must grow, allocate a new one and free old array only after all lookups finish. * elf/dl-runtime.c (_dl_fixup): Protect using global scope. (_dl_lookup_symbol_x): Likewise. * elf/dl-support.c: Define _dl_wait_lookup_done. * sysdeps/generic/ldsodefs.h (struct rtld_global): Add _dl_wait_lookup_done.
461 lines
15 KiB
C
461 lines
15 KiB
C
/* On-demand PLT fixup for shared objects.
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Copyright (C) 1995-2006, 2007 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 Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the 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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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; if not, write to the Free
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Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
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02111-1307 USA. */
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#define IN_DL_RUNTIME 1 /* This can be tested in dl-machine.h. */
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#include <alloca.h>
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#include <stdlib.h>
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#include <unistd.h>
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#include <sys/param.h>
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#include <ldsodefs.h>
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#include <sysdep-cancel.h>
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#include "dynamic-link.h"
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#include <tls.h>
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#if (!defined ELF_MACHINE_NO_RELA && !defined ELF_MACHINE_PLT_REL) \
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|| ELF_MACHINE_NO_REL
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# define PLTREL ElfW(Rela)
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#else
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# define PLTREL ElfW(Rel)
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#endif
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#ifndef VERSYMIDX
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# define VERSYMIDX(sym) (DT_NUM + DT_THISPROCNUM + DT_VERSIONTAGIDX (sym))
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#endif
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/* The fixup functions might have need special attributes. If none
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are provided define the macro as empty. */
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#ifndef ARCH_FIXUP_ATTRIBUTE
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# define ARCH_FIXUP_ATTRIBUTE
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#endif
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/* This function is called through a special trampoline from the PLT the
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first time each PLT entry is called. We must perform the relocation
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specified in the PLT of the given shared object, and return the resolved
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function address to the trampoline, which will restart the original call
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to that address. Future calls will bounce directly from the PLT to the
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function. */
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#ifndef ELF_MACHINE_NO_PLT
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DL_FIXUP_VALUE_TYPE
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__attribute ((noinline)) ARCH_FIXUP_ATTRIBUTE
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_dl_fixup (
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# ifdef ELF_MACHINE_RUNTIME_FIXUP_ARGS
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ELF_MACHINE_RUNTIME_FIXUP_ARGS,
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# endif
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/* GKM FIXME: Fix trampoline to pass bounds so we can do
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without the `__unbounded' qualifier. */
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struct link_map *__unbounded l, ElfW(Word) reloc_offset)
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{
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const ElfW(Sym) *const symtab
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= (const void *) D_PTR (l, l_info[DT_SYMTAB]);
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const char *strtab = (const void *) D_PTR (l, l_info[DT_STRTAB]);
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const PLTREL *const reloc
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= (const void *) (D_PTR (l, l_info[DT_JMPREL]) + reloc_offset);
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const ElfW(Sym) *sym = &symtab[ELFW(R_SYM) (reloc->r_info)];
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void *const rel_addr = (void *)(l->l_addr + reloc->r_offset);
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lookup_t result;
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DL_FIXUP_VALUE_TYPE value;
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/* Sanity check that we're really looking at a PLT relocation. */
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assert (ELFW(R_TYPE)(reloc->r_info) == ELF_MACHINE_JMP_SLOT);
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/* Look up the target symbol. If the normal lookup rules are not
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used don't look in the global scope. */
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if (__builtin_expect (ELFW(ST_VISIBILITY) (sym->st_other), 0) == 0)
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{
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const struct r_found_version *version = NULL;
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if (l->l_info[VERSYMIDX (DT_VERSYM)] != NULL)
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{
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const ElfW(Half) *vernum =
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(const void *) D_PTR (l, l_info[VERSYMIDX (DT_VERSYM)]);
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ElfW(Half) ndx = vernum[ELFW(R_SYM) (reloc->r_info)] & 0x7fff;
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version = &l->l_versions[ndx];
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if (version->hash == 0)
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version = NULL;
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}
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/* We need to keep the scope around so do some locking. This is
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not necessary for objects which cannot be unloaded or when
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we are not using any threads (yet). */
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int flags = DL_LOOKUP_ADD_DEPENDENCY;
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if (!RTLD_SINGLE_THREAD_P)
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{
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THREAD_GSCOPE_SET_FLAG ();
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if (l->l_type == lt_loaded)
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{
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__rtld_mrlock_lock (l->l_scope_lock);
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flags |= DL_LOOKUP_SCOPE_LOCK;
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}
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}
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result = _dl_lookup_symbol_x (strtab + sym->st_name, l, &sym, l->l_scope,
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version, ELF_RTYPE_CLASS_PLT, flags, NULL);
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if ((flags & DL_LOOKUP_SCOPE_LOCK) != 0)
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__rtld_mrlock_unlock (l->l_scope_lock);
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/* We are done with the global scope. */
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if (!RTLD_SINGLE_THREAD_P)
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THREAD_GSCOPE_RESET_FLAG ();
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/* Currently result contains the base load address (or link map)
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of the object that defines sym. Now add in the symbol
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offset. */
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value = DL_FIXUP_MAKE_VALUE (result,
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sym ? (LOOKUP_VALUE_ADDRESS (result)
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+ sym->st_value) : 0);
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}
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else
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{
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/* We already found the symbol. The module (and therefore its load
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address) is also known. */
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value = DL_FIXUP_MAKE_VALUE (l, l->l_addr + sym->st_value);
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result = l;
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}
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/* And now perhaps the relocation addend. */
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value = elf_machine_plt_value (l, reloc, value);
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/* Finally, fix up the plt itself. */
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if (__builtin_expect (GLRO(dl_bind_not), 0))
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return value;
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return elf_machine_fixup_plt (l, result, reloc, rel_addr, value);
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}
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#endif
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#if !defined PROF && !defined ELF_MACHINE_NO_PLT && !__BOUNDED_POINTERS__
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DL_FIXUP_VALUE_TYPE
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__attribute ((noinline)) ARCH_FIXUP_ATTRIBUTE
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_dl_profile_fixup (
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#ifdef ELF_MACHINE_RUNTIME_FIXUP_ARGS
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ELF_MACHINE_RUNTIME_FIXUP_ARGS,
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#endif
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struct link_map *l, ElfW(Word) reloc_offset,
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ElfW(Addr) retaddr, void *regs, long int *framesizep)
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{
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void (*mcount_fct) (ElfW(Addr), ElfW(Addr)) = INTUSE(_dl_mcount);
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/* This is the address in the array where we store the result of previous
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relocations. */
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struct reloc_result *reloc_result
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= &l->l_reloc_result[reloc_offset / sizeof (PLTREL)];
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DL_FIXUP_VALUE_TYPE *resultp = &reloc_result->addr;
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DL_FIXUP_VALUE_TYPE value = *resultp;
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if (DL_FIXUP_VALUE_CODE_ADDR (value) == 0)
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{
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/* This is the first time we have to relocate this object. */
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const ElfW(Sym) *const symtab
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= (const void *) D_PTR (l, l_info[DT_SYMTAB]);
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const char *strtab = (const char *) D_PTR (l, l_info[DT_STRTAB]);
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const PLTREL *const reloc
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= (const void *) (D_PTR (l, l_info[DT_JMPREL]) + reloc_offset);
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const ElfW(Sym) *refsym = &symtab[ELFW(R_SYM) (reloc->r_info)];
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const ElfW(Sym) *defsym = refsym;
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lookup_t result;
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/* Sanity check that we're really looking at a PLT relocation. */
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assert (ELFW(R_TYPE)(reloc->r_info) == ELF_MACHINE_JMP_SLOT);
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/* Look up the target symbol. If the symbol is marked STV_PROTECTED
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don't look in the global scope. */
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if (__builtin_expect (ELFW(ST_VISIBILITY) (refsym->st_other), 0) == 0)
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{
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const struct r_found_version *version = NULL;
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if (l->l_info[VERSYMIDX (DT_VERSYM)] != NULL)
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{
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const ElfW(Half) *vernum =
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(const void *) D_PTR (l, l_info[VERSYMIDX (DT_VERSYM)]);
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ElfW(Half) ndx = vernum[ELFW(R_SYM) (reloc->r_info)] & 0x7fff;
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version = &l->l_versions[ndx];
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if (version->hash == 0)
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version = NULL;
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}
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/* We need to keep the scope around so do some locking. This is
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not necessary for objects which cannot be unloaded or when
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we are not using any threads (yet). */
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int flags = DL_LOOKUP_ADD_DEPENDENCY;
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if (!RTLD_SINGLE_THREAD_P)
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{
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THREAD_GSCOPE_SET_FLAG ();
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if (l->l_type == lt_loaded)
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{
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__rtld_mrlock_lock (l->l_scope_lock);
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flags |= DL_LOOKUP_SCOPE_LOCK;
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}
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}
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result = _dl_lookup_symbol_x (strtab + refsym->st_name, l,
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&defsym, l->l_scope, version,
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ELF_RTYPE_CLASS_PLT, flags, NULL);
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if ((flags & DL_LOOKUP_SCOPE_LOCK) != 0)
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__rtld_mrlock_unlock (l->l_scope_lock);
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/* We are done with the global scope. */
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if (!RTLD_SINGLE_THREAD_P)
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THREAD_GSCOPE_RESET_FLAG ();
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/* Currently result contains the base load address (or link map)
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of the object that defines sym. Now add in the symbol
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offset. */
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value = DL_FIXUP_MAKE_VALUE (result,
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defsym != NULL
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? LOOKUP_VALUE_ADDRESS (result)
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+ defsym->st_value : 0);
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}
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else
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{
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/* We already found the symbol. The module (and therefore its load
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address) is also known. */
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value = DL_FIXUP_MAKE_VALUE (l, l->l_addr + refsym->st_value);
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result = l;
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}
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/* And now perhaps the relocation addend. */
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value = elf_machine_plt_value (l, reloc, value);
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#ifdef SHARED
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/* Auditing checkpoint: we have a new binding. Provide the
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auditing libraries the possibility to change the value and
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tell us whether further auditing is wanted. */
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if (defsym != NULL && GLRO(dl_naudit) > 0)
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{
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reloc_result->bound = result;
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/* Compute index of the symbol entry in the symbol table of
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the DSO with the definition. */
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reloc_result->boundndx = (defsym
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- (ElfW(Sym) *) D_PTR (result,
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l_info[DT_SYMTAB]));
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/* Determine whether any of the two participating DSOs is
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interested in auditing. */
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if ((l->l_audit_any_plt | result->l_audit_any_plt) != 0)
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{
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unsigned int altvalue = 0;
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struct audit_ifaces *afct = GLRO(dl_audit);
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/* Synthesize a symbol record where the st_value field is
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the result. */
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ElfW(Sym) sym = *defsym;
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sym.st_value = DL_FIXUP_VALUE_ADDR (value);
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/* Keep track whether there is any interest in tracing
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the call in the lower two bits. */
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assert (DL_NNS * 2 <= sizeof (reloc_result->flags) * 8);
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assert ((LA_SYMB_NOPLTENTER | LA_SYMB_NOPLTEXIT) == 3);
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reloc_result->enterexit = LA_SYMB_NOPLTENTER | LA_SYMB_NOPLTEXIT;
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const char *strtab2 = (const void *) D_PTR (result,
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l_info[DT_STRTAB]);
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for (unsigned int cnt = 0; cnt < GLRO(dl_naudit); ++cnt)
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{
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/* XXX Check whether both DSOs must request action or
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only one */
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if ((l->l_audit[cnt].bindflags & LA_FLG_BINDFROM) != 0
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&& (result->l_audit[cnt].bindflags & LA_FLG_BINDTO) != 0)
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{
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unsigned int flags = altvalue;
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if (afct->symbind != NULL)
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{
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uintptr_t new_value
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= afct->symbind (&sym, reloc_result->boundndx,
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&l->l_audit[cnt].cookie,
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&result->l_audit[cnt].cookie,
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&flags,
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strtab2 + defsym->st_name);
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if (new_value != (uintptr_t) sym.st_value)
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{
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altvalue = LA_SYMB_ALTVALUE;
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sym.st_value = new_value;
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}
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}
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/* Remember the results for every audit library and
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store a summary in the first two bits. */
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reloc_result->enterexit
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&= flags & (LA_SYMB_NOPLTENTER | LA_SYMB_NOPLTEXIT);
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reloc_result->enterexit
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|= ((flags & (LA_SYMB_NOPLTENTER | LA_SYMB_NOPLTEXIT))
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<< ((cnt + 1) * 2));
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}
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else
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/* If the bind flags say this auditor is not interested,
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set the bits manually. */
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reloc_result->enterexit
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|= ((LA_SYMB_NOPLTENTER | LA_SYMB_NOPLTEXIT)
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<< ((cnt + 1) * 2));
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afct = afct->next;
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}
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reloc_result->flags = altvalue;
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value = DL_FIXUP_ADDR_VALUE (sym.st_value);
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}
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else
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/* Set all bits since this symbol binding is not interesting. */
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reloc_result->enterexit = (1u << DL_NNS) - 1;
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}
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#endif
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/* Store the result for later runs. */
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if (__builtin_expect (! GLRO(dl_bind_not), 1))
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*resultp = value;
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}
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/* By default we do not call the pltexit function. */
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long int framesize = -1;
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#ifdef SHARED
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/* Auditing checkpoint: report the PLT entering and allow the
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auditors to change the value. */
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if (DL_FIXUP_VALUE_CODE_ADDR (value) != 0 && GLRO(dl_naudit) > 0
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/* Don't do anything if no auditor wants to intercept this call. */
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&& (reloc_result->enterexit & LA_SYMB_NOPLTENTER) == 0)
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{
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ElfW(Sym) *defsym = ((ElfW(Sym) *) D_PTR (reloc_result->bound,
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l_info[DT_SYMTAB])
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+ reloc_result->boundndx);
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/* Set up the sym parameter. */
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ElfW(Sym) sym = *defsym;
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sym.st_value = DL_FIXUP_VALUE_ADDR (value);
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/* Get the symbol name. */
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const char *strtab = (const void *) D_PTR (reloc_result->bound,
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l_info[DT_STRTAB]);
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const char *symname = strtab + sym.st_name;
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/* Keep track of overwritten addresses. */
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unsigned int altvalue = reloc_result->flags;
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struct audit_ifaces *afct = GLRO(dl_audit);
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for (unsigned int cnt = 0; cnt < GLRO(dl_naudit); ++cnt)
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{
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if (afct->ARCH_LA_PLTENTER != NULL
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&& (reloc_result->enterexit
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& (LA_SYMB_NOPLTENTER << (2 * (cnt + 1)))) == 0)
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{
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unsigned int flags = altvalue;
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long int new_framesize = -1;
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uintptr_t new_value
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= afct->ARCH_LA_PLTENTER (&sym, reloc_result->boundndx,
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&l->l_audit[cnt].cookie,
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&reloc_result->bound->l_audit[cnt].cookie,
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regs, &flags, symname,
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&new_framesize);
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if (new_value != (uintptr_t) sym.st_value)
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{
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altvalue = LA_SYMB_ALTVALUE;
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sym.st_value = new_value;
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}
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/* Remember the results for every audit library and
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store a summary in the first two bits. */
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reloc_result->enterexit
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|= ((flags & (LA_SYMB_NOPLTENTER | LA_SYMB_NOPLTEXIT))
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<< (2 * (cnt + 1)));
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if ((reloc_result->enterexit & (LA_SYMB_NOPLTEXIT
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<< (2 * (cnt + 1))))
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== 0 && new_framesize != -1 && framesize != -2)
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{
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/* If this is the first call providing information,
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use it. */
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if (framesize == -1)
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framesize = new_framesize;
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/* If two pltenter calls provide conflicting information,
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use the larger value. */
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else if (new_framesize != framesize)
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framesize = MAX (new_framesize, framesize);
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}
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}
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afct = afct->next;
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}
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value = DL_FIXUP_ADDR_VALUE (sym.st_value);
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}
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#endif
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/* Store the frame size information. */
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*framesizep = framesize;
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(*mcount_fct) (retaddr, DL_FIXUP_VALUE_CODE_ADDR (value));
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return value;
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}
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#endif /* PROF && ELF_MACHINE_NO_PLT */
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#include <stdio.h>
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void
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ARCH_FIXUP_ATTRIBUTE
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_dl_call_pltexit (struct link_map *l, ElfW(Word) reloc_offset,
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const void *inregs, void *outregs)
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{
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#ifdef SHARED
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/* This is the address in the array where we store the result of previous
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relocations. */
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// XXX Maybe the bound information must be stored on the stack since
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// XXX with bind_not a new value could have been stored in the meantime.
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struct reloc_result *reloc_result
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= &l->l_reloc_result[reloc_offset / sizeof (PLTREL)];
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ElfW(Sym) *defsym = ((ElfW(Sym) *) D_PTR (reloc_result->bound,
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l_info[DT_SYMTAB])
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+ reloc_result->boundndx);
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/* Set up the sym parameter. */
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ElfW(Sym) sym = *defsym;
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/* Get the symbol name. */
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const char *strtab = (const void *) D_PTR (reloc_result->bound,
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l_info[DT_STRTAB]);
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const char *symname = strtab + sym.st_name;
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struct audit_ifaces *afct = GLRO(dl_audit);
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for (unsigned int cnt = 0; cnt < GLRO(dl_naudit); ++cnt)
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{
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if (afct->ARCH_LA_PLTEXIT != NULL
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&& (reloc_result->enterexit
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& (LA_SYMB_NOPLTEXIT >> (2 * cnt))) == 0)
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{
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afct->ARCH_LA_PLTEXIT (&sym, reloc_result->boundndx,
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&l->l_audit[cnt].cookie,
|
|
&reloc_result->bound->l_audit[cnt].cookie,
|
|
inregs, outregs, symname);
|
|
}
|
|
|
|
afct = afct->next;
|
|
}
|
|
#endif
|
|
}
|