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authorH.J. Lu <hjl.tools@gmail.com>2015-03-31 05:15:43 -0700
committerH.J. Lu <hjl.tools@gmail.com>2015-03-31 17:05:21 -0700
commitd817d6f3d6f3bde4b7e2d85a8d6dccd418d701c7 (patch)
treed25ddddec6b48a63cece69a0526d74cb94570262
parent4d54424420c6300efbf57a7b9aa8635a8b8c1942 (diff)
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Add ELF_RTYPE_CLASS_EXTERN_PROTECTED_DATA to x86
With copy relocation, address of protected data defined in the shared library may be external. When there is a relocation against the protected data symbol within the shared library, we need to check if we should skip the definition in the executable copied from the protected data. This patch adds ELF_RTYPE_CLASS_EXTERN_PROTECTED_DATA and defines it for x86. If ELF_RTYPE_CLASS_EXTERN_PROTECTED_DATA isn't 0, do_lookup_x will skip the data definition in the executable from copy reloc. Cherry-pick from master: 62da1e3b00b51383ffa7efc89d8addda0502e107 [BZ #17711] * elf/dl-lookup.c (do_lookup_x): When UNDEF_MAP is NULL, which indicates it is called from do_lookup_x on relocation against protected data, skip the data definion in the executable from copy reloc. (_dl_lookup_symbol_x): Pass ELF_RTYPE_CLASS_EXTERN_PROTECTED_DATA, instead of ELF_RTYPE_CLASS_PLT, to do_lookup_x for EXTERN_PROTECTED_DATA relocation against STT_OBJECT symbol. * sysdeps/generic/ldsodefs.h * (ELF_RTYPE_CLASS_EXTERN_PROTECTED_DATA): New. Defined to 4 if DL_EXTERN_PROTECTED_DATA is defined, otherwise to 0. * sysdeps/i386/dl-lookupcfg.h (DL_EXTERN_PROTECTED_DATA): New. * sysdeps/i386/dl-machine.h (elf_machine_type_class): Set class to ELF_RTYPE_CLASS_EXTERN_PROTECTED_DATA for R_386_GLOB_DAT. * sysdeps/x86_64/dl-lookupcfg.h (DL_EXTERN_PROTECTED_DATA): New. * sysdeps/x86_64/dl-machine.h (elf_machine_type_class): Set class to ELF_RTYPE_CLASS_EXTERN_PROTECTED_DATA for R_X86_64_GLOB_DAT.
-rw-r--r--elf/dl-lookup.c61
-rw-r--r--sysdeps/generic/ldsodefs.h12
-rw-r--r--sysdeps/i386/dl-lookupcfg.h4
-rw-r--r--sysdeps/i386/dl-machine.h8
-rw-r--r--sysdeps/x86_64/dl-lookupcfg.h4
-rw-r--r--sysdeps/x86_64/dl-machine.h8
6 files changed, 91 insertions, 6 deletions
diff --git a/elf/dl-lookup.c b/elf/dl-lookup.c
index 7c32830a301..42c3054e55b 100644
--- a/elf/dl-lookup.c
+++ b/elf/dl-lookup.c
@@ -460,6 +460,59 @@ do_lookup_x (const char *undef_name, uint_fast32_t new_hash,
if (sym != NULL)
{
found_it:
+ /* When UNDEF_MAP is NULL, which indicates we are called from
+ do_lookup_x on relocation against protected data, we skip
+ the data definion in the executable from copy reloc. */
+ if (ELF_RTYPE_CLASS_EXTERN_PROTECTED_DATA
+ && undef_map == NULL
+ && map->l_type == lt_executable
+ && type_class == ELF_RTYPE_CLASS_EXTERN_PROTECTED_DATA)
+ {
+ const ElfW(Sym) *s;
+ unsigned int i;
+
+#if ! ELF_MACHINE_NO_RELA
+ if (map->l_info[DT_RELA] != NULL
+ && map->l_info[DT_RELASZ] != NULL
+ && map->l_info[DT_RELASZ]->d_un.d_val != 0)
+ {
+ const ElfW(Rela) *rela
+ = (const ElfW(Rela) *) D_PTR (map, l_info[DT_RELA]);
+ unsigned int rela_count
+ = map->l_info[DT_RELASZ]->d_un.d_val / sizeof (*rela);
+
+ for (i = 0; i < rela_count; i++, rela++)
+ if (elf_machine_type_class (ELFW(R_TYPE) (rela->r_info))
+ == ELF_RTYPE_CLASS_COPY)
+ {
+ s = &symtab[ELFW(R_SYM) (rela->r_info)];
+ if (!strcmp (strtab + s->st_name, undef_name))
+ goto skip;
+ }
+ }
+#endif
+#if ! ELF_MACHINE_NO_REL
+ if (map->l_info[DT_REL] != NULL
+ && map->l_info[DT_RELSZ] != NULL
+ && map->l_info[DT_RELSZ]->d_un.d_val != 0)
+ {
+ const ElfW(Rel) *rel
+ = (const ElfW(Rel) *) D_PTR (map, l_info[DT_REL]);
+ unsigned int rel_count
+ = map->l_info[DT_RELSZ]->d_un.d_val / sizeof (*rel);
+
+ for (i = 0; i < rel_count; i++, rel++)
+ if (elf_machine_type_class (ELFW(R_TYPE) (rel->r_info))
+ == ELF_RTYPE_CLASS_COPY)
+ {
+ s = &symtab[ELFW(R_SYM) (rel->r_info)];
+ if (!strcmp (strtab + s->st_name, undef_name))
+ goto skip;
+ }
+ }
+#endif
+ }
+
switch (ELFW(ST_BIND) (sym->st_info))
{
case STB_WEAK:
@@ -491,6 +544,7 @@ do_lookup_x (const char *undef_name, uint_fast32_t new_hash,
}
}
+skip:
/* If this current map is the one mentioned in the verneed entry
and we have not found a weak entry, it is a bug. */
if (symidx == STN_UNDEF && version != NULL && version->filename != NULL
@@ -841,7 +895,12 @@ _dl_lookup_symbol_x (const char *undef_name, struct link_map *undef_map,
for (scope = symbol_scope; *scope != NULL; i = 0, ++scope)
if (do_lookup_x (undef_name, new_hash, &old_hash, *ref,
&protected_value, *scope, i, version, flags,
- skip_map, ELF_RTYPE_CLASS_PLT, NULL) != 0)
+ skip_map,
+ (ELF_RTYPE_CLASS_EXTERN_PROTECTED_DATA
+ && ELFW(ST_TYPE) ((*ref)->st_info) == STT_OBJECT
+ && type_class == ELF_RTYPE_CLASS_EXTERN_PROTECTED_DATA)
+ ? ELF_RTYPE_CLASS_EXTERN_PROTECTED_DATA
+ : ELF_RTYPE_CLASS_PLT, NULL) != 0)
break;
if (protected_value.s != NULL && protected_value.m != undef_map)
diff --git a/sysdeps/generic/ldsodefs.h b/sysdeps/generic/ldsodefs.h
index e01df84a994..8c4a9610431 100644
--- a/sysdeps/generic/ldsodefs.h
+++ b/sysdeps/generic/ldsodefs.h
@@ -105,13 +105,23 @@ typedef struct link_map *lookup_t;
satisfied by any symbol in the executable. Some architectures do
not support copy relocations. In this case we define the macro to
zero so that the code for handling them gets automatically optimized
- out. */
+ out. ELF_RTYPE_CLASS_EXTERN_PROTECTED_DATA means address of protected
+ data defined in the shared library may be external, i.e., due to copy
+ relocation. */
#define ELF_RTYPE_CLASS_PLT 1
#ifndef DL_NO_COPY_RELOCS
# define ELF_RTYPE_CLASS_COPY 2
#else
# define ELF_RTYPE_CLASS_COPY 0
#endif
+/* If DL_EXTERN_PROTECTED_DATA is defined, address of protected data
+ defined in the shared library may be external, i.e., due to copy
+ relocation. */
+#ifdef DL_EXTERN_PROTECTED_DATA
+# define ELF_RTYPE_CLASS_EXTERN_PROTECTED_DATA 4
+#else
+# define ELF_RTYPE_CLASS_EXTERN_PROTECTED_DATA 0
+#endif
/* ELF uses the PF_x macros to specify the segment permissions, mmap
uses PROT_xxx. In most cases the three macros have the values 1, 2,
diff --git a/sysdeps/i386/dl-lookupcfg.h b/sysdeps/i386/dl-lookupcfg.h
index 3fea8b4ab18..a9916b9f3c8 100644
--- a/sysdeps/i386/dl-lookupcfg.h
+++ b/sysdeps/i386/dl-lookupcfg.h
@@ -20,6 +20,10 @@
#include_next <dl-lookupcfg.h>
+/* Address of protected data defined in the shared library may be
+ external due to copy relocation. */
+#define DL_EXTERN_PROTECTED_DATA
+
struct link_map;
extern void internal_function _dl_unmap (struct link_map *map);
diff --git a/sysdeps/i386/dl-machine.h b/sysdeps/i386/dl-machine.h
index a3a632cda28..5cbd6fb71a7 100644
--- a/sysdeps/i386/dl-machine.h
+++ b/sysdeps/i386/dl-machine.h
@@ -239,13 +239,17 @@ _dl_start_user:\n\
TLS variable, so undefined references should not be allowed to
define the value.
ELF_RTYPE_CLASS_NOCOPY iff TYPE should not be allowed to resolve to one
- of the main executable's symbols, as for a COPY reloc. */
+ of the main executable's symbols, as for a COPY reloc.
+ ELF_RTYPE_CLASS_EXTERN_PROTECTED_DATA iff TYPE describes relocation may
+ against protected data whose address be external due to copy relocation.
+ */
# define elf_machine_type_class(type) \
((((type) == R_386_JMP_SLOT || (type) == R_386_TLS_DTPMOD32 \
|| (type) == R_386_TLS_DTPOFF32 || (type) == R_386_TLS_TPOFF32 \
|| (type) == R_386_TLS_TPOFF || (type) == R_386_TLS_DESC) \
* ELF_RTYPE_CLASS_PLT) \
- | (((type) == R_386_COPY) * ELF_RTYPE_CLASS_COPY))
+ | (((type) == R_386_COPY) * ELF_RTYPE_CLASS_COPY) \
+ | (((type) == R_386_GLOB_DAT) * ELF_RTYPE_CLASS_EXTERN_PROTECTED_DATA))
/* A reloc type used for ld.so cmdline arg lookups to reject PLT entries. */
#define ELF_MACHINE_JMP_SLOT R_386_JMP_SLOT
diff --git a/sysdeps/x86_64/dl-lookupcfg.h b/sysdeps/x86_64/dl-lookupcfg.h
index 3fea8b4ab18..a9916b9f3c8 100644
--- a/sysdeps/x86_64/dl-lookupcfg.h
+++ b/sysdeps/x86_64/dl-lookupcfg.h
@@ -20,6 +20,10 @@
#include_next <dl-lookupcfg.h>
+/* Address of protected data defined in the shared library may be
+ external due to copy relocation. */
+#define DL_EXTERN_PROTECTED_DATA
+
struct link_map;
extern void internal_function _dl_unmap (struct link_map *map);
diff --git a/sysdeps/x86_64/dl-machine.h b/sysdeps/x86_64/dl-machine.h
index f9ee1f79b65..357b64c9917 100644
--- a/sysdeps/x86_64/dl-machine.h
+++ b/sysdeps/x86_64/dl-machine.h
@@ -170,7 +170,10 @@ _dl_start_user:\n\
TLS variable, so undefined references should not be allowed to
define the value.
ELF_RTYPE_CLASS_NOCOPY iff TYPE should not be allowed to resolve to one
- of the main executable's symbols, as for a COPY reloc. */
+ of the main executable's symbols, as for a COPY reloc.
+ ELF_RTYPE_CLASS_EXTERN_PROTECTED_DATA iff TYPE describes relocation may
+ against protected data whose address be external due to copy relocation.
+ */
#define elf_machine_type_class(type) \
((((type) == R_X86_64_JUMP_SLOT \
|| (type) == R_X86_64_DTPMOD64 \
@@ -178,7 +181,8 @@ _dl_start_user:\n\
|| (type) == R_X86_64_TPOFF64 \
|| (type) == R_X86_64_TLSDESC) \
* ELF_RTYPE_CLASS_PLT) \
- | (((type) == R_X86_64_COPY) * ELF_RTYPE_CLASS_COPY))
+ | (((type) == R_X86_64_COPY) * ELF_RTYPE_CLASS_COPY) \
+ | (((type) == R_X86_64_GLOB_DAT) * ELF_RTYPE_CLASS_EXTERN_PROTECTED_DATA))
/* A reloc type used for ld.so cmdline arg lookups to reject PLT entries. */
#define ELF_MACHINE_JMP_SLOT R_X86_64_JUMP_SLOT