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am 92c6e988: am 224aee2f: am 486d99f0: Merge "Don\'t allow text relocations on 64-bit."

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* commit '92c6e988cda228f7255c9050dfa9ea10a2082432':
  Don't allow text relocations on 64-bit.
This commit is contained in:
Elliott Hughes 2013-10-28 14:45:08 -07:00 committed by Android Git Automerger
commit 50cadd942c
4 changed files with 65 additions and 27 deletions
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44
libc/include/sys/exec_elf.h
View File

@ -1,4 +1,4 @@
/* $NetBSD: exec_elf.h,v 1.126 2012/08/05 01:43:59 matt Exp $ */
/* $NetBSD: exec_elf.h,v 1.129 2013/09/10 16:24:02 matt Exp $ */
/*-
* Copyright (c) 1994 The NetBSD Foundation, Inc.
@ -429,6 +429,13 @@ typedef struct {
#define SHT_HIOS 0x6fffffff
#define SHT_LOPROC 0x70000000 /* Processor-specific range */
#define SHT_AMD64_UNWIND 0x70000001 /* unwind information */
#define SHT_ARM_EXIDX 0x70000001 /* exception index table */
#define SHT_ARM_PREEMPTMAP 0x70000002 /* BPABI DLL dynamic linking
* pre-emption map */
#define SHT_ARM_ATTRIBUTES 0x70000003 /* Object file compatibility
* attributes */
#define SHT_ARM_DEBUGOVERLAY 0x70000004 /* See DBGOVL for details */
#define SHT_ARM_OVERLAYSECTION 0x70000005
#define SHT_HIPROC 0x7fffffff
#define SHT_LOUSER 0x80000000 /* Application-specific range */
#define SHT_HIUSER 0xffffffff
@ -668,7 +675,12 @@ typedef struct {
#define DT_FINI_ARRAY 26 /* Size, in bytes, of DT_INIT_ARRAY array */
#define DT_INIT_ARRAYSZ 27 /* Address of termination function array */
#define DT_FINI_ARRAYSZ 28 /* Size, in bytes, of DT_FINI_ARRAY array*/
#define DT_NUM 29
#define DT_RUNPATH 29 /* overrides DT_RPATH */
#define DT_FLAGS 30 /* Encodes ORIGIN, SYMBOLIC, TEXTREL, BIND_NOW, STATIC_TLS */
#define DT_ENCODING 31 /* ??? */
#define DT_PREINIT_ARRAY 32 /* Address of pre-init function array */
#define DT_PREINIT_ARRAYSZ 33 /* Size, in bytes, of DT_PREINIT_ARRAY array */
#define DT_NUM 34
#define DT_LOOS 0x60000000 /* Operating system specific range */
#define DT_VERSYM 0x6ffffff0 /* Symbol versions */
@ -802,7 +814,7 @@ typedef struct {
* GNU-specific note type: Build ID generated by ld
* name: GNU\0
* desc:
* word[0..4] SHA1 [default]
* word[0..4] SHA1 [default]
* or
* word[0..3] md5 or uuid
* descsz: 16 or 20
@ -829,7 +841,7 @@ typedef struct {
/* SuSE-specific note type: version
* name: SuSE\0\0\0\0
* namesz: 8
* desc:
* desc:
* word[0] = VVTTMMmm
*
* V = version of following data
@ -848,7 +860,7 @@ typedef struct {
/* NetBSD-specific note type: Emulation name.
* name: NetBSD\0\0
* namesz: 8
* desc:
* desc:
* word[0]: MMmmrrpp00
*
* M = major version
@ -864,7 +876,7 @@ typedef struct {
/* NetBSD-specific note name */
#define ELF_NOTE_NETBSD_NAME "NetBSD\0\0"
/* NetBSD-specific note type: Checksum.
/* NetBSD-specific note type: Checksum.
* There should be 1 NOTE per PT_LOAD section.
* name: ???
* namesz: ???
@ -953,6 +965,20 @@ struct netbsd_elfcore_procinfo {
int32_t cpi_siglwp; /* LWP target of killing signal */
};
/*
* NetBSD-specific note type: MACHINE_ARCH.
* There should be 1 NOTE per executable.
* name: NetBSD\0
* namesz: 7
* desc: string
* descsz: variable
*/
#define ELF_NOTE_TYPE_MARCH_TAG 5
/* NetBSD-specific note name and description sizes */
#define ELF_NOTE_MARCH_NAMESZ ELF_NOTE_NETBSD_NAMESZ
/* NetBSD-specific note name */
#define ELF_NOTE_MARCH_NAME ELF_NOTE_NETBSD_NAME
#if !defined(ELFSIZE) && defined(ARCH_ELFSIZE)
#define ELFSIZE ARCH_ELFSIZE
#endif
@ -1067,7 +1093,7 @@ typedef struct {
#define SYMINFO_NUM 2
/*
* These constants are used for Elf32_Verdef struct's version number.
* These constants are used for Elf32_Verdef struct's version number.
*/
#define VER_DEF_NONE 0
#define VER_DEF_CURRENT 1
@ -1078,7 +1104,7 @@ typedef struct {
#define VER_DEF_IDX(x) VER_NDX(x)
/*
* These constants are used for Elf32_Verdef struct's vd_flags.
* These constants are used for Elf32_Verdef struct's vd_flags.
*/
#define VER_FLG_BASE 0x1
#define VER_FLG_WEAK 0x2
@ -1091,7 +1117,7 @@ typedef struct {
#define VER_NDX_GIVEN 2
/*
* These constants are used for Elf32_Verneed struct's version number.
* These constants are used for Elf32_Verneed struct's version number.
*/
#define VER_NEED_NONE 0
#define VER_NEED_CURRENT 1

2
linker/dlfcn.cpp
View File

@ -295,6 +295,8 @@ soinfo libdl_info = {
{ .l_addr = 0, .l_name = 0, .l_ld = 0, .l_next = 0, .l_prev = 0, },
.constructors_called = false,
.load_bias = 0,
#if !defined(__LP64__)
.has_text_relocations = false,
#endif
.has_DT_SYMBOLIC = true,
};

27
linker/linker.cpp
View File

@ -1548,25 +1548,32 @@ static bool soinfo_link_image(soinfo* si) {
si->preinit_array_count = ((unsigned)d->d_un.d_val) / sizeof(Elf_Addr);
break;
case DT_TEXTREL:
#if defined(__LP64__)
DL_ERR("text relocations (DT_TEXTREL) found in 64-bit ELF file \"%s\"", si->name);
return false;
#else
si->has_text_relocations = true;
break;
#endif
case DT_SYMBOLIC:
si->has_DT_SYMBOLIC = true;
break;
case DT_NEEDED:
++needed_count;
break;
#if defined DT_FLAGS
// TODO: why is DT_FLAGS not defined?
case DT_FLAGS:
if (d->d_un.d_val & DF_TEXTREL) {
#if defined(__LP64__)
DL_ERR("text relocations (DF_TEXTREL) found in 64-bit ELF file \"%s\"", si->name);
return false;
#else
si->has_text_relocations = true;
#endif
}
if (d->d_un.d_val & DF_SYMBOLIC) {
si->has_DT_SYMBOLIC = true;
}
break;
#endif
#if defined(__mips__)
case DT_STRSZ:
case DT_SYMENT:
@ -1661,12 +1668,10 @@ static bool soinfo_link_image(soinfo* si) {
}
*pneeded = NULL;
#if !defined(__LP64__)
if (si->has_text_relocations) {
/* Unprotect the segments, i.e. make them writable, to allow
* text relocations to work properly. We will later call
* phdr_table_protect_segments() after all of them are applied
* and all constructors are run.
*/
// Make segments writable to allow text relocations to work properly. We will later call
// phdr_table_protect_segments() after all of them are applied and all constructors are run.
DL_WARN("%s has text relocations. This is wasting memory and prevents "
"security hardening. Please fix.", si->name);
if (phdr_table_unprotect_segments(si->phdr, si->phnum, si->load_bias) < 0) {
@ -1675,6 +1680,7 @@ static bool soinfo_link_image(soinfo* si) {
return false;
}
}
#endif
#if defined(USE_RELA)
if (si->plt_rela != NULL) {
@ -1713,15 +1719,16 @@ static bool soinfo_link_image(soinfo* si) {
si->flags |= FLAG_LINKED;
DEBUG("[ finished linking %s ]", si->name);
#if !defined(__LP64__)
if (si->has_text_relocations) {
/* All relocations are done, we can protect our segments back to
* read-only. */
// All relocations are done, we can protect our segments back to read-only.
if (phdr_table_protect_segments(si->phdr, si->phnum, si->load_bias) < 0) {
DL_ERR("can't protect segments for \"%s\": %s",
si->name, strerror(errno));
return false;
}
}
#endif
/* We can also turn on GNU RELRO protection */
if (phdr_table_protect_gnu_relro(si->phdr, si->phnum, si->load_bias) < 0) {

19
linker/linker.h
View File

@ -183,7 +183,9 @@ struct soinfo {
// value to get the corresponding address in the process' address space.
Elf_Addr load_bias;
#if !defined(__LP64__)
bool has_text_relocations;
#endif
bool has_DT_SYMBOLIC;
void CallConstructors();
@ -195,15 +197,16 @@ struct soinfo {
void CallFunction(const char* function_name, linker_function_t function);
};
extern soinfo libdl_info;
// The possible DT_FLAGS bits are in
// http://www.sco.com/developers/gabi/latest/ch5.dynamic.html#dynamic_section
// but not in the upstream NetBSD <sys/exec_elf.h> header file ours is based on.
#define DF_ORIGIN 0x1
#define DF_SYMBOLIC 0x2
#define DF_TEXTREL 0x4
#define DF_BIND_NOW 0x8
#define DF_STATIC_TLS 0x10
// These aren't defined in <sys/exec_elf.h>.
#ifndef DT_PREINIT_ARRAY
#define DT_PREINIT_ARRAY 32
#endif
#ifndef DT_PREINIT_ARRAYSZ
#define DT_PREINIT_ARRAYSZ 33
#endif
extern soinfo libdl_info;
void do_android_update_LD_LIBRARY_PATH(const char* ld_library_path);
soinfo* do_dlopen(const char* name, int flags);