/* On-demand PLT fixup for shared objects.
- Copyright (C) 1995-1999, 2000 Free Software Foundation, Inc.
+ Copyright (C) 1995-2016 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 Library General Public License as
- published by the Free Software Foundation; either version 2 of the
- License, or (at your option) any later version.
+ 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
- Library General Public License for more details.
+ Lesser General Public License for more details.
- You should have received a copy of the GNU Library General Public
- License along with the GNU C Library; see the file COPYING.LIB. If not,
- write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
- Boston, MA 02111-1307, USA. */
+ You should have received a copy of the GNU Lesser General Public
+ License along with the GNU C Library; if not, see
+ <http://www.gnu.org/licenses/>. */
+
+#define IN_DL_RUNTIME 1 /* This can be tested in dl-machine.h. */
#include <alloca.h>
#include <stdlib.h>
#include <unistd.h>
+#include <sys/param.h>
#include <ldsodefs.h>
+#include <sysdep-cancel.h>
#include "dynamic-link.h"
+#include <tls.h>
+#include <dl-irel.h>
+
-#if !defined ELF_MACHINE_NO_RELA || ELF_MACHINE_NO_REL
+#if (!ELF_MACHINE_NO_RELA && !defined ELF_MACHINE_PLT_REL) \
+ || ELF_MACHINE_NO_REL
# define PLTREL ElfW(Rela)
#else
# define PLTREL ElfW(Rel)
#endif
-#ifndef VERSYMIDX
-# define VERSYMIDX(sym) (DT_NUM + DT_PROCNUM + DT_VERSIONTAGIDX (sym))
+/* The fixup functions might have need special attributes. If none
+ are provided define the macro as empty. */
+#ifndef ARCH_FIXUP_ATTRIBUTE
+# define ARCH_FIXUP_ATTRIBUTE
+#endif
+
+#ifndef reloc_offset
+# define reloc_offset reloc_arg
+# define reloc_index reloc_arg / sizeof (PLTREL)
#endif
+
/* This function is called through a special trampoline from the PLT the
first time each PLT entry is called. We must perform the relocation
specified in the PLT of the given shared object, and return the resolved
to that address. Future calls will bounce directly from the PLT to the
function. */
-#ifndef ELF_MACHINE_NO_PLT
-static ElfW(Addr) __attribute__ ((unused))
-fixup (
+DL_FIXUP_VALUE_TYPE
+attribute_hidden __attribute ((noinline)) ARCH_FIXUP_ATTRIBUTE
+_dl_fixup (
# ifdef ELF_MACHINE_RUNTIME_FIXUP_ARGS
- ELF_MACHINE_RUNTIME_FIXUP_ARGS,
+ ELF_MACHINE_RUNTIME_FIXUP_ARGS,
# endif
- struct link_map *l, ElfW(Word) reloc_offset)
+ struct link_map *l, ElfW(Word) reloc_arg)
{
const ElfW(Sym) *const symtab
= (const void *) D_PTR (l, l_info[DT_SYMTAB]);
= (const void *) (D_PTR (l, l_info[DT_JMPREL]) + reloc_offset);
const ElfW(Sym) *sym = &symtab[ELFW(R_SYM) (reloc->r_info)];
void *const rel_addr = (void *)(l->l_addr + reloc->r_offset);
- ElfW(Addr) value;
-
- /* The use of `alloca' here looks ridiculous but it helps. The goal is
- to prevent the function from being inlined and thus optimized out.
- There is no official way to do this so we use this trick. gcc never
- inlines functions which use `alloca'. */
- alloca (sizeof (int));
+ lookup_t result;
+ DL_FIXUP_VALUE_TYPE value;
/* Sanity check that we're really looking at a PLT relocation. */
assert (ELFW(R_TYPE)(reloc->r_info) == ELF_MACHINE_JMP_SLOT);
- /* Look up the target symbol. If the symbol is marked STV_PROTEXTED
- don't look in the global scope. */
- if (ELFW(ST_VISIBILITY) (sym->st_other) != STV_PROTECTED)
+ /* Look up the target symbol. If the normal lookup rules are not
+ used don't look in the global scope. */
+ if (__builtin_expect (ELFW(ST_VISIBILITY) (sym->st_other), 0) == 0)
{
- switch (l->l_info[VERSYMIDX (DT_VERSYM)] != NULL)
+ const struct r_found_version *version = NULL;
+
+ if (l->l_info[VERSYMIDX (DT_VERSYM)] != NULL)
+ {
+ const ElfW(Half) *vernum =
+ (const void *) D_PTR (l, l_info[VERSYMIDX (DT_VERSYM)]);
+ ElfW(Half) ndx = vernum[ELFW(R_SYM) (reloc->r_info)] & 0x7fff;
+ version = &l->l_versions[ndx];
+ if (version->hash == 0)
+ version = NULL;
+ }
+
+ /* We need to keep the scope around so do some locking. This is
+ not necessary for objects which cannot be unloaded or when
+ we are not using any threads (yet). */
+ int flags = DL_LOOKUP_ADD_DEPENDENCY;
+ if (!RTLD_SINGLE_THREAD_P)
{
- default:
- {
- const ElfW(Half) *vernum =
- (const void *) D_PTR (l, l_info[VERSYMIDX (DT_VERSYM)]);
- ElfW(Half) ndx = vernum[ELFW(R_SYM) (reloc->r_info)];
- const struct r_found_version *version = &l->l_versions[ndx];
-
- if (version->hash != 0)
- {
- value = _dl_lookup_versioned_symbol(strtab + sym->st_name, l,
- &sym, l->l_scope, version,
- ELF_MACHINE_JMP_SLOT);
- break;
- }
- }
- case 0:
- value = _dl_lookup_symbol (strtab + sym->st_name, l, &sym,
- l->l_scope, ELF_MACHINE_JMP_SLOT);
+ THREAD_GSCOPE_SET_FLAG ();
+ flags |= DL_LOOKUP_GSCOPE_LOCK;
}
- /* Currently value contains the base load address of the object
- that defines sym. Now add in the symbol offset. */
- value = (sym ? value + sym->st_value : 0);
+#ifdef RTLD_ENABLE_FOREIGN_CALL
+ RTLD_ENABLE_FOREIGN_CALL;
+#endif
+
+ result = _dl_lookup_symbol_x (strtab + sym->st_name, l, &sym, l->l_scope,
+ version, ELF_RTYPE_CLASS_PLT, flags, NULL);
+
+ /* We are done with the global scope. */
+ if (!RTLD_SINGLE_THREAD_P)
+ THREAD_GSCOPE_RESET_FLAG ();
+
+#ifdef RTLD_FINALIZE_FOREIGN_CALL
+ RTLD_FINALIZE_FOREIGN_CALL;
+#endif
+
+ /* Currently result contains the base load address (or link map)
+ of the object that defines sym. Now add in the symbol
+ offset. */
+ value = DL_FIXUP_MAKE_VALUE (result,
+ sym ? (LOOKUP_VALUE_ADDRESS (result)
+ + sym->st_value) : 0);
}
else
- /* We already found the symbol. The module (and therefore its load
- address) is also known. */
- value = l->l_addr + sym->st_value;
+ {
+ /* We already found the symbol. The module (and therefore its load
+ address) is also known. */
+ value = DL_FIXUP_MAKE_VALUE (l, l->l_addr + sym->st_value);
+ result = l;
+ }
/* And now perhaps the relocation addend. */
value = elf_machine_plt_value (l, reloc, value);
+ if (sym != NULL
+ && __builtin_expect (ELFW(ST_TYPE) (sym->st_info) == STT_GNU_IFUNC, 0))
+ value = elf_ifunc_invoke (DL_FIXUP_VALUE_ADDR (value));
+
/* Finally, fix up the plt itself. */
- elf_machine_fixup_plt (l, reloc, rel_addr, value);
+ if (__glibc_unlikely (GLRO(dl_bind_not)))
+ return value;
- return value;
+ return elf_machine_fixup_plt (l, result, reloc, rel_addr, value);
}
-#endif
-
-#if !defined PROF && !defined ELF_MACHINE_NO_PLT
-static ElfW(Addr) __attribute__ ((unused))
-profile_fixup (
+#ifndef PROF
+DL_FIXUP_VALUE_TYPE
+__attribute ((noinline)) ARCH_FIXUP_ATTRIBUTE
+_dl_profile_fixup (
#ifdef ELF_MACHINE_RUNTIME_FIXUP_ARGS
- ELF_MACHINE_RUNTIME_FIXUP_ARGS,
+ ELF_MACHINE_RUNTIME_FIXUP_ARGS,
#endif
- struct link_map *l, ElfW(Word) reloc_offset, ElfW(Addr) retaddr)
+ struct link_map *l, ElfW(Word) reloc_arg,
+ ElfW(Addr) retaddr, void *regs, long int *framesizep)
{
void (*mcount_fct) (ElfW(Addr), ElfW(Addr)) = _dl_mcount;
- ElfW(Addr) *resultp;
- ElfW(Addr) value;
- /* The use of `alloca' here looks ridiculous but it helps. The goal is
- to prevent the function from being inlined, and thus optimized out.
- There is no official way to do this so we use this trick. gcc never
- inlines functions which use `alloca'. */
- alloca (sizeof (int));
+ if (l->l_reloc_result == NULL)
+ {
+ /* BZ #14843: ELF_DYNAMIC_RELOCATE is called before l_reloc_result
+ is allocated. We will get here if ELF_DYNAMIC_RELOCATE calls a
+ resolver function to resolve an IRELATIVE relocation and that
+ resolver calls a function that is not yet resolved (lazy). For
+ example, the resolver in x86-64 libm.so calls __get_cpu_features
+ defined in libc.so. Skip audit and resolve the external function
+ in this case. */
+ *framesizep = -1;
+ return _dl_fixup (
+# ifdef ELF_MACHINE_RUNTIME_FIXUP_ARGS
+# ifndef ELF_MACHINE_RUNTIME_FIXUP_PARAMS
+# error Please define ELF_MACHINE_RUNTIME_FIXUP_PARAMS.
+# endif
+ ELF_MACHINE_RUNTIME_FIXUP_PARAMS,
+# endif
+ l, reloc_arg);
+ }
/* This is the address in the array where we store the result of previous
relocations. */
- resultp = &l->l_reloc_result[reloc_offset / sizeof (PLTREL)];
+ struct reloc_result *reloc_result = &l->l_reloc_result[reloc_index];
+ DL_FIXUP_VALUE_TYPE *resultp = &reloc_result->addr;
- value = *resultp;
- if (value == 0)
+ DL_FIXUP_VALUE_TYPE value = *resultp;
+ if (DL_FIXUP_VALUE_CODE_ADDR (value) == 0)
{
/* This is the first time we have to relocate this object. */
const ElfW(Sym) *const symtab
= (const void *) D_PTR (l, l_info[DT_SYMTAB]);
- const char *strtab = (const void *) D_PTR (l, l_info[DT_STRTAB]);
+ const char *strtab = (const char *) D_PTR (l, l_info[DT_STRTAB]);
const PLTREL *const reloc
= (const void *) (D_PTR (l, l_info[DT_JMPREL]) + reloc_offset);
- const ElfW(Sym) *sym = &symtab[ELFW(R_SYM) (reloc->r_info)];
+ const ElfW(Sym) *refsym = &symtab[ELFW(R_SYM) (reloc->r_info)];
+ const ElfW(Sym) *defsym = refsym;
+ lookup_t result;
/* Sanity check that we're really looking at a PLT relocation. */
assert (ELFW(R_TYPE)(reloc->r_info) == ELF_MACHINE_JMP_SLOT);
- /* Look up the target symbol. If the symbol is marked STV_PROTEXTED
+ /* Look up the target symbol. If the symbol is marked STV_PROTECTED
don't look in the global scope. */
- if (ELFW(ST_VISIBILITY) (sym->st_other) != STV_PROTECTED)
+ if (__builtin_expect (ELFW(ST_VISIBILITY) (refsym->st_other), 0) == 0)
{
- switch (l->l_info[VERSYMIDX (DT_VERSYM)] != NULL)
+ const struct r_found_version *version = NULL;
+
+ if (l->l_info[VERSYMIDX (DT_VERSYM)] != NULL)
+ {
+ const ElfW(Half) *vernum =
+ (const void *) D_PTR (l, l_info[VERSYMIDX (DT_VERSYM)]);
+ ElfW(Half) ndx = vernum[ELFW(R_SYM) (reloc->r_info)] & 0x7fff;
+ version = &l->l_versions[ndx];
+ if (version->hash == 0)
+ version = NULL;
+ }
+
+ /* We need to keep the scope around so do some locking. This is
+ not necessary for objects which cannot be unloaded or when
+ we are not using any threads (yet). */
+ int flags = DL_LOOKUP_ADD_DEPENDENCY;
+ if (!RTLD_SINGLE_THREAD_P)
{
- default:
- {
- const ElfW(Half) *vernum =
- (const void *) D_PTR (l,l_info[VERSYMIDX (DT_VERSYM)]);
- ElfW(Half) ndx = vernum[ELFW(R_SYM) (reloc->r_info)];
- const struct r_found_version *version = &l->l_versions[ndx];
-
- if (version->hash != 0)
- {
- value = _dl_lookup_versioned_symbol(strtab + sym->st_name,
- l, &sym, l->l_scope,
- version,
- ELF_MACHINE_JMP_SLOT);
- break;
- }
- }
- case 0:
- value = _dl_lookup_symbol (strtab + sym->st_name, l, &sym,
- l->l_scope, ELF_MACHINE_JMP_SLOT);
+ THREAD_GSCOPE_SET_FLAG ();
+ flags |= DL_LOOKUP_GSCOPE_LOCK;
}
- /* Currently value contains the base load address of the object
- that defines sym. Now add in the symbol offset. */
- value = (sym ? value + sym->st_value : 0);
+ result = _dl_lookup_symbol_x (strtab + refsym->st_name, l,
+ &defsym, l->l_scope, version,
+ ELF_RTYPE_CLASS_PLT, flags, NULL);
+
+ /* We are done with the global scope. */
+ if (!RTLD_SINGLE_THREAD_P)
+ THREAD_GSCOPE_RESET_FLAG ();
+
+ /* Currently result contains the base load address (or link map)
+ of the object that defines sym. Now add in the symbol
+ offset. */
+ value = DL_FIXUP_MAKE_VALUE (result,
+ defsym != NULL
+ ? LOOKUP_VALUE_ADDRESS (result)
+ + defsym->st_value : 0);
+
+ if (defsym != NULL
+ && __builtin_expect (ELFW(ST_TYPE) (defsym->st_info)
+ == STT_GNU_IFUNC, 0))
+ value = elf_ifunc_invoke (DL_FIXUP_VALUE_ADDR (value));
}
else
- /* We already found the symbol. The module (and therefore its load
- address) is also known. */
- value = l->l_addr + sym->st_value;
+ {
+ /* We already found the symbol. The module (and therefore its load
+ address) is also known. */
+ value = DL_FIXUP_MAKE_VALUE (l, l->l_addr + refsym->st_value);
+
+ if (__builtin_expect (ELFW(ST_TYPE) (refsym->st_info)
+ == STT_GNU_IFUNC, 0))
+ value = elf_ifunc_invoke (DL_FIXUP_VALUE_ADDR (value));
+ result = l;
+ }
/* And now perhaps the relocation addend. */
value = elf_machine_plt_value (l, reloc, value);
+#ifdef SHARED
+ /* Auditing checkpoint: we have a new binding. Provide the
+ auditing libraries the possibility to change the value and
+ tell us whether further auditing is wanted. */
+ if (defsym != NULL && GLRO(dl_naudit) > 0)
+ {
+ reloc_result->bound = result;
+ /* Compute index of the symbol entry in the symbol table of
+ the DSO with the definition. */
+ reloc_result->boundndx = (defsym
+ - (ElfW(Sym) *) D_PTR (result,
+ l_info[DT_SYMTAB]));
+
+ /* Determine whether any of the two participating DSOs is
+ interested in auditing. */
+ if ((l->l_audit_any_plt | result->l_audit_any_plt) != 0)
+ {
+ unsigned int flags = 0;
+ struct audit_ifaces *afct = GLRO(dl_audit);
+ /* Synthesize a symbol record where the st_value field is
+ the result. */
+ ElfW(Sym) sym = *defsym;
+ sym.st_value = DL_FIXUP_VALUE_ADDR (value);
+
+ /* Keep track whether there is any interest in tracing
+ the call in the lower two bits. */
+ assert (DL_NNS * 2 <= sizeof (reloc_result->flags) * 8);
+ assert ((LA_SYMB_NOPLTENTER | LA_SYMB_NOPLTEXIT) == 3);
+ reloc_result->enterexit = LA_SYMB_NOPLTENTER | LA_SYMB_NOPLTEXIT;
+
+ const char *strtab2 = (const void *) D_PTR (result,
+ l_info[DT_STRTAB]);
+
+ for (unsigned int cnt = 0; cnt < GLRO(dl_naudit); ++cnt)
+ {
+ /* XXX Check whether both DSOs must request action or
+ only one */
+ if ((l->l_audit[cnt].bindflags & LA_FLG_BINDFROM) != 0
+ && (result->l_audit[cnt].bindflags & LA_FLG_BINDTO) != 0)
+ {
+ if (afct->symbind != NULL)
+ {
+ uintptr_t new_value
+ = afct->symbind (&sym, reloc_result->boundndx,
+ &l->l_audit[cnt].cookie,
+ &result->l_audit[cnt].cookie,
+ &flags,
+ strtab2 + defsym->st_name);
+ if (new_value != (uintptr_t) sym.st_value)
+ {
+ flags |= LA_SYMB_ALTVALUE;
+ sym.st_value = new_value;
+ }
+ }
+
+ /* Remember the results for every audit library and
+ store a summary in the first two bits. */
+ reloc_result->enterexit
+ &= flags & (LA_SYMB_NOPLTENTER | LA_SYMB_NOPLTEXIT);
+ reloc_result->enterexit
+ |= ((flags & (LA_SYMB_NOPLTENTER | LA_SYMB_NOPLTEXIT))
+ << ((cnt + 1) * 2));
+ }
+ else
+ /* If the bind flags say this auditor is not interested,
+ set the bits manually. */
+ reloc_result->enterexit
+ |= ((LA_SYMB_NOPLTENTER | LA_SYMB_NOPLTEXIT)
+ << ((cnt + 1) * 2));
+
+ afct = afct->next;
+ }
+
+ reloc_result->flags = flags;
+ value = DL_FIXUP_ADDR_VALUE (sym.st_value);
+ }
+ else
+ /* Set all bits since this symbol binding is not interesting. */
+ reloc_result->enterexit = (1u << DL_NNS) - 1;
+ }
+#endif
+
/* Store the result for later runs. */
- *resultp = value;
+ if (__glibc_likely (! GLRO(dl_bind_not)))
+ *resultp = value;
+ }
+
+ /* By default we do not call the pltexit function. */
+ long int framesize = -1;
+
+#ifdef SHARED
+ /* Auditing checkpoint: report the PLT entering and allow the
+ auditors to change the value. */
+ if (DL_FIXUP_VALUE_CODE_ADDR (value) != 0 && GLRO(dl_naudit) > 0
+ /* Don't do anything if no auditor wants to intercept this call. */
+ && (reloc_result->enterexit & LA_SYMB_NOPLTENTER) == 0)
+ {
+ ElfW(Sym) *defsym = ((ElfW(Sym) *) D_PTR (reloc_result->bound,
+ l_info[DT_SYMTAB])
+ + reloc_result->boundndx);
+
+ /* Set up the sym parameter. */
+ ElfW(Sym) sym = *defsym;
+ sym.st_value = DL_FIXUP_VALUE_ADDR (value);
+
+ /* Get the symbol name. */
+ const char *strtab = (const void *) D_PTR (reloc_result->bound,
+ l_info[DT_STRTAB]);
+ const char *symname = strtab + sym.st_name;
+
+ /* Keep track of overwritten addresses. */
+ unsigned int flags = reloc_result->flags;
+
+ struct audit_ifaces *afct = GLRO(dl_audit);
+ for (unsigned int cnt = 0; cnt < GLRO(dl_naudit); ++cnt)
+ {
+ if (afct->ARCH_LA_PLTENTER != NULL
+ && (reloc_result->enterexit
+ & (LA_SYMB_NOPLTENTER << (2 * (cnt + 1)))) == 0)
+ {
+ long int new_framesize = -1;
+ uintptr_t new_value
+ = afct->ARCH_LA_PLTENTER (&sym, reloc_result->boundndx,
+ &l->l_audit[cnt].cookie,
+ &reloc_result->bound->l_audit[cnt].cookie,
+ regs, &flags, symname,
+ &new_framesize);
+ if (new_value != (uintptr_t) sym.st_value)
+ {
+ flags |= LA_SYMB_ALTVALUE;
+ sym.st_value = new_value;
+ }
+
+ /* Remember the results for every audit library and
+ store a summary in the first two bits. */
+ reloc_result->enterexit
+ |= ((flags & (LA_SYMB_NOPLTENTER | LA_SYMB_NOPLTEXIT))
+ << (2 * (cnt + 1)));
+
+ if ((reloc_result->enterexit & (LA_SYMB_NOPLTEXIT
+ << (2 * (cnt + 1))))
+ == 0 && new_framesize != -1 && framesize != -2)
+ {
+ /* If this is the first call providing information,
+ use it. */
+ if (framesize == -1)
+ framesize = new_framesize;
+ /* If two pltenter calls provide conflicting information,
+ use the larger value. */
+ else if (new_framesize != framesize)
+ framesize = MAX (new_framesize, framesize);
+ }
+ }
+
+ afct = afct->next;
+ }
+
+ value = DL_FIXUP_ADDR_VALUE (sym.st_value);
}
+#endif
- (*mcount_fct) (retaddr, value);
+ /* Store the frame size information. */
+ *framesizep = framesize;
+
+ (*mcount_fct) (retaddr, DL_FIXUP_VALUE_CODE_ADDR (value));
return value;
}
-#endif /* PROF && ELF_MACHINE_NO_PLT */
+#endif /* PROF */
-/* This macro is defined in dl-machine.h to define the entry point called
- by the PLT. The `fixup' function above does the real work, but a little
- more twiddling is needed to get the stack right and jump to the address
- finally resolved. */
+#include <stdio.h>
+void
+ARCH_FIXUP_ATTRIBUTE
+_dl_call_pltexit (struct link_map *l, ElfW(Word) reloc_arg,
+ const void *inregs, void *outregs)
+{
+#ifdef SHARED
+ /* This is the address in the array where we store the result of previous
+ relocations. */
+ // XXX Maybe the bound information must be stored on the stack since
+ // XXX with bind_not a new value could have been stored in the meantime.
+ struct reloc_result *reloc_result = &l->l_reloc_result[reloc_index];
+ ElfW(Sym) *defsym = ((ElfW(Sym) *) D_PTR (reloc_result->bound,
+ l_info[DT_SYMTAB])
+ + reloc_result->boundndx);
+
+ /* Set up the sym parameter. */
+ ElfW(Sym) sym = *defsym;
+ sym.st_value = DL_FIXUP_VALUE_ADDR (reloc_result->addr);
+
+ /* Get the symbol name. */
+ const char *strtab = (const void *) D_PTR (reloc_result->bound,
+ l_info[DT_STRTAB]);
+ const char *symname = strtab + sym.st_name;
+
+ struct audit_ifaces *afct = GLRO(dl_audit);
+ for (unsigned int cnt = 0; cnt < GLRO(dl_naudit); ++cnt)
+ {
+ if (afct->ARCH_LA_PLTEXIT != NULL
+ && (reloc_result->enterexit
+ & (LA_SYMB_NOPLTEXIT >> (2 * cnt))) == 0)
+ {
+ afct->ARCH_LA_PLTEXIT (&sym, reloc_result->boundndx,
+ &l->l_audit[cnt].cookie,
+ &reloc_result->bound->l_audit[cnt].cookie,
+ inregs, outregs, symname);
+ }
-ELF_MACHINE_RUNTIME_TRAMPOLINE
+ afct = afct->next;
+ }
+#endif
+}
projects / thirdparty / glibc.git / blobdiff