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Remove 32-bit assumptions from the ELF code.

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Change-Id: I2c1f3d34c33685799aade8866eec44479ff9f963
This commit is contained in:
Elliott Hughes
2013-09-30 18:43:46 -07:00
parent 6dee3b9aee
commit c620059479
13 changed files with 212 additions and 261 deletions
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178
linker/linker_phdr.cpp
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@@ -49,7 +49,7 @@
p_vaddr -> segment's virtual address
p_flags -> segment flags (e.g. readable, writable, executable)
We will ignore the p_paddr and p_align fields of Elf32_Phdr for now.
We will ignore the p_paddr and p_align fields of Elf_Phdr for now.
The loadable segments can be seen as a list of [p_vaddr ... p_vaddr+p_memsz)
ranges of virtual addresses. A few rules apply:
@@ -147,8 +147,8 @@ bool ElfReader::ReadElfHeader() {
return false;
}
if (rc != sizeof(header_)) {
DL_ERR("\"%s\" is too small to be an ELF executable. Expected at least %d bytes, only found %d bytes.",
name_, sizeof(header_), rc);
DL_ERR("\"%s\" is too small to be an ELF executable: only found %zd bytes", name_,
static_cast<size_t>(rc));
return false;
}
return true;
@@ -205,14 +205,14 @@ bool ElfReader::ReadProgramHeader() {
// Like the kernel, we only accept program header tables that
// are smaller than 64KiB.
if (phdr_num_ < 1 || phdr_num_ > 65536/sizeof(Elf32_Phdr)) {
DL_ERR("\"%s\" has invalid e_phnum: %d", name_, phdr_num_);
if (phdr_num_ < 1 || phdr_num_ > 65536/sizeof(Elf_Phdr)) {
DL_ERR("\"%s\" has invalid e_phnum: %zd", name_, phdr_num_);
return false;
}
Elf32_Addr page_min = PAGE_START(header_.e_phoff);
Elf32_Addr page_max = PAGE_END(header_.e_phoff + (phdr_num_ * sizeof(Elf32_Phdr)));
Elf32_Addr page_offset = PAGE_OFFSET(header_.e_phoff);
Elf_Addr page_min = PAGE_START(header_.e_phoff);
Elf_Addr page_max = PAGE_END(header_.e_phoff + (phdr_num_ * sizeof(Elf_Phdr)));
Elf_Addr page_offset = PAGE_OFFSET(header_.e_phoff);
phdr_size_ = page_max - page_min;
@@ -223,7 +223,7 @@ bool ElfReader::ReadProgramHeader() {
}
phdr_mmap_ = mmap_result;
phdr_table_ = reinterpret_cast<Elf32_Phdr*>(reinterpret_cast<char*>(mmap_result) + page_offset);
phdr_table_ = reinterpret_cast<Elf_Phdr*>(reinterpret_cast<char*>(mmap_result) + page_offset);
return true;
}
@@ -237,17 +237,15 @@ bool ElfReader::ReadProgramHeader() {
* set to the minimum and maximum addresses of pages to be reserved,
* or 0 if there is nothing to load.
*/
size_t phdr_table_get_load_size(const Elf32_Phdr* phdr_table,
size_t phdr_count,
Elf32_Addr* out_min_vaddr,
Elf32_Addr* out_max_vaddr)
{
Elf32_Addr min_vaddr = 0xFFFFFFFFU;
Elf32_Addr max_vaddr = 0x00000000U;
size_t phdr_table_get_load_size(const Elf_Phdr* phdr_table, size_t phdr_count,
Elf_Addr* out_min_vaddr,
Elf_Addr* out_max_vaddr) {
Elf_Addr min_vaddr = 0xFFFFFFFFU;
Elf_Addr max_vaddr = 0x00000000U;
bool found_pt_load = false;
for (size_t i = 0; i < phdr_count; ++i) {
const Elf32_Phdr* phdr = &phdr_table[i];
const Elf_Phdr* phdr = &phdr_table[i];
if (phdr->p_type != PT_LOAD) {
continue;
@@ -282,7 +280,7 @@ size_t phdr_table_get_load_size(const Elf32_Phdr* phdr_table,
// segments of a program header table. This is done by creating a
// private anonymous mmap() with PROT_NONE.
bool ElfReader::ReserveAddressSpace() {
Elf32_Addr min_vaddr;
Elf_Addr min_vaddr;
load_size_ = phdr_table_get_load_size(phdr_table_, phdr_num_, &min_vaddr);
if (load_size_ == 0) {
DL_ERR("\"%s\" has no loadable segments", name_);
@@ -308,27 +306,27 @@ bool ElfReader::ReserveAddressSpace() {
// TODO: assert assumption.
bool ElfReader::LoadSegments() {
for (size_t i = 0; i < phdr_num_; ++i) {
const Elf32_Phdr* phdr = &phdr_table_[i];
const Elf_Phdr* phdr = &phdr_table_[i];
if (phdr->p_type != PT_LOAD) {
continue;
}
// Segment addresses in memory.
Elf32_Addr seg_start = phdr->p_vaddr + load_bias_;
Elf32_Addr seg_end = seg_start + phdr->p_memsz;
Elf_Addr seg_start = phdr->p_vaddr + load_bias_;
Elf_Addr seg_end = seg_start + phdr->p_memsz;
Elf32_Addr seg_page_start = PAGE_START(seg_start);
Elf32_Addr seg_page_end = PAGE_END(seg_end);
Elf_Addr seg_page_start = PAGE_START(seg_start);
Elf_Addr seg_page_end = PAGE_END(seg_end);
Elf32_Addr seg_file_end = seg_start + phdr->p_filesz;
Elf_Addr seg_file_end = seg_start + phdr->p_filesz;
// File offsets.
Elf32_Addr file_start = phdr->p_offset;
Elf32_Addr file_end = file_start + phdr->p_filesz;
Elf_Addr file_start = phdr->p_offset;
Elf_Addr file_end = file_start + phdr->p_filesz;
Elf32_Addr file_page_start = PAGE_START(file_start);
Elf32_Addr file_length = file_end - file_page_start;
Elf_Addr file_page_start = PAGE_START(file_start);
Elf_Addr file_length = file_end - file_page_start;
if (file_length != 0) {
void* seg_addr = mmap((void*)seg_page_start,
@@ -338,7 +336,7 @@ bool ElfReader::LoadSegments() {
fd_,
file_page_start);
if (seg_addr == MAP_FAILED) {
DL_ERR("couldn't map \"%s\" segment %d: %s", name_, i, strerror(errno));
DL_ERR("couldn't map \"%s\" segment %zd: %s", name_, i, strerror(errno));
return false;
}
}
@@ -375,21 +373,17 @@ bool ElfReader::LoadSegments() {
* with optional extra flags (i.e. really PROT_WRITE). Used by
* phdr_table_protect_segments and phdr_table_unprotect_segments.
*/
static int
_phdr_table_set_load_prot(const Elf32_Phdr* phdr_table,
int phdr_count,
Elf32_Addr load_bias,
int extra_prot_flags)
{
const Elf32_Phdr* phdr = phdr_table;
const Elf32_Phdr* phdr_limit = phdr + phdr_count;
static int _phdr_table_set_load_prot(const Elf_Phdr* phdr_table, size_t phdr_count,
Elf_Addr load_bias, int extra_prot_flags) {
const Elf_Phdr* phdr = phdr_table;
const Elf_Phdr* phdr_limit = phdr + phdr_count;
for (; phdr < phdr_limit; phdr++) {
if (phdr->p_type != PT_LOAD || (phdr->p_flags & PF_W) != 0)
continue;
Elf32_Addr seg_page_start = PAGE_START(phdr->p_vaddr) + load_bias;
Elf32_Addr seg_page_end = PAGE_END(phdr->p_vaddr + phdr->p_memsz) + load_bias;
Elf_Addr seg_page_start = PAGE_START(phdr->p_vaddr) + load_bias;
Elf_Addr seg_page_end = PAGE_END(phdr->p_vaddr + phdr->p_memsz) + load_bias;
int ret = mprotect((void*)seg_page_start,
seg_page_end - seg_page_start,
@@ -412,13 +406,8 @@ _phdr_table_set_load_prot(const Elf32_Phdr* phdr_table,
* Return:
* 0 on error, -1 on failure (error code in errno).
*/
int
phdr_table_protect_segments(const Elf32_Phdr* phdr_table,
int phdr_count,
Elf32_Addr load_bias)
{
return _phdr_table_set_load_prot(phdr_table, phdr_count,
load_bias, 0);
int phdr_table_protect_segments(const Elf_Phdr* phdr_table, size_t phdr_count, Elf_Addr load_bias) {
return _phdr_table_set_load_prot(phdr_table, phdr_count, load_bias, 0);
}
/* Change the protection of all loaded segments in memory to writable.
@@ -437,26 +426,17 @@ phdr_table_protect_segments(const Elf32_Phdr* phdr_table,
* Return:
* 0 on error, -1 on failure (error code in errno).
*/
int
phdr_table_unprotect_segments(const Elf32_Phdr* phdr_table,
int phdr_count,
Elf32_Addr load_bias)
{
return _phdr_table_set_load_prot(phdr_table, phdr_count,
load_bias, PROT_WRITE);
int phdr_table_unprotect_segments(const Elf_Phdr* phdr_table, size_t phdr_count, Elf_Addr load_bias) {
return _phdr_table_set_load_prot(phdr_table, phdr_count, load_bias, PROT_WRITE);
}
/* Used internally by phdr_table_protect_gnu_relro and
* phdr_table_unprotect_gnu_relro.
*/
static int
_phdr_table_set_gnu_relro_prot(const Elf32_Phdr* phdr_table,
int phdr_count,
Elf32_Addr load_bias,
int prot_flags)
{
const Elf32_Phdr* phdr = phdr_table;
const Elf32_Phdr* phdr_limit = phdr + phdr_count;
static int _phdr_table_set_gnu_relro_prot(const Elf_Phdr* phdr_table, size_t phdr_count,
Elf_Addr load_bias, int prot_flags) {
const Elf_Phdr* phdr = phdr_table;
const Elf_Phdr* phdr_limit = phdr + phdr_count;
for (phdr = phdr_table; phdr < phdr_limit; phdr++) {
if (phdr->p_type != PT_GNU_RELRO)
@@ -479,8 +459,8 @@ _phdr_table_set_gnu_relro_prot(const Elf32_Phdr* phdr_table,
* linker must only emit a PT_GNU_RELRO segment if it ensures
* that it starts on a page boundary.
*/
Elf32_Addr seg_page_start = PAGE_START(phdr->p_vaddr) + load_bias;
Elf32_Addr seg_page_end = PAGE_END(phdr->p_vaddr + phdr->p_memsz) + load_bias;
Elf_Addr seg_page_start = PAGE_START(phdr->p_vaddr) + load_bias;
Elf_Addr seg_page_end = PAGE_END(phdr->p_vaddr + phdr->p_memsz) + load_bias;
int ret = mprotect((void*)seg_page_start,
seg_page_end - seg_page_start,
@@ -508,15 +488,8 @@ _phdr_table_set_gnu_relro_prot(const Elf32_Phdr* phdr_table,
* Return:
* 0 on error, -1 on failure (error code in errno).
*/
int
phdr_table_protect_gnu_relro(const Elf32_Phdr* phdr_table,
int phdr_count,
Elf32_Addr load_bias)
{
return _phdr_table_set_gnu_relro_prot(phdr_table,
phdr_count,
load_bias,
PROT_READ);
int phdr_table_protect_gnu_relro(const Elf_Phdr* phdr_table, size_t phdr_count, Elf_Addr load_bias) {
return _phdr_table_set_gnu_relro_prot(phdr_table, phdr_count, load_bias, PROT_READ);
}
#ifdef ANDROID_ARM_LINKER
@@ -538,21 +511,17 @@ phdr_table_protect_gnu_relro(const Elf32_Phdr* phdr_table,
* Return:
* 0 on error, -1 on failure (_no_ error code in errno)
*/
int
phdr_table_get_arm_exidx(const Elf32_Phdr* phdr_table,
int phdr_count,
Elf32_Addr load_bias,
Elf32_Addr** arm_exidx,
unsigned* arm_exidx_count)
{
const Elf32_Phdr* phdr = phdr_table;
const Elf32_Phdr* phdr_limit = phdr + phdr_count;
int phdr_table_get_arm_exidx(const Elf_Phdr* phdr_table, size_t phdr_count,
Elf_Addr load_bias,
Elf_Addr** arm_exidx, unsigned* arm_exidx_count) {
const Elf_Phdr* phdr = phdr_table;
const Elf_Phdr* phdr_limit = phdr + phdr_count;
for (phdr = phdr_table; phdr < phdr_limit; phdr++) {
if (phdr->p_type != PT_ARM_EXIDX)
continue;
*arm_exidx = (Elf32_Addr*)(load_bias + phdr->p_vaddr);
*arm_exidx = (Elf_Addr*)(load_bias + phdr->p_vaddr);
*arm_exidx_count = (unsigned)(phdr->p_memsz / 8);
return 0;
}
@@ -576,23 +545,18 @@ phdr_table_get_arm_exidx(const Elf32_Phdr* phdr_table,
* Return:
* void
*/
void
phdr_table_get_dynamic_section(const Elf32_Phdr* phdr_table,
int phdr_count,
Elf32_Addr load_bias,
Elf32_Dyn** dynamic,
size_t* dynamic_count,
Elf32_Word* dynamic_flags)
{
const Elf32_Phdr* phdr = phdr_table;
const Elf32_Phdr* phdr_limit = phdr + phdr_count;
void phdr_table_get_dynamic_section(const Elf_Phdr* phdr_table, size_t phdr_count,
Elf_Addr load_bias,
Elf_Dyn** dynamic, size_t* dynamic_count, Elf_Word* dynamic_flags) {
const Elf_Phdr* phdr = phdr_table;
const Elf_Phdr* phdr_limit = phdr + phdr_count;
for (phdr = phdr_table; phdr < phdr_limit; phdr++) {
if (phdr->p_type != PT_DYNAMIC) {
continue;
}
*dynamic = reinterpret_cast<Elf32_Dyn*>(load_bias + phdr->p_vaddr);
*dynamic = reinterpret_cast<Elf_Dyn*>(load_bias + phdr->p_vaddr);
if (dynamic_count) {
*dynamic_count = (unsigned)(phdr->p_memsz / 8);
}
@@ -611,10 +575,10 @@ phdr_table_get_dynamic_section(const Elf32_Phdr* phdr_table,
// segments in memory. This is in contrast with 'phdr_table_' which
// is temporary and will be released before the library is relocated.
bool ElfReader::FindPhdr() {
const Elf32_Phdr* phdr_limit = phdr_table_ + phdr_num_;
const Elf_Phdr* phdr_limit = phdr_table_ + phdr_num_;
// If there is a PT_PHDR, use it directly.
for (const Elf32_Phdr* phdr = phdr_table_; phdr < phdr_limit; ++phdr) {
for (const Elf_Phdr* phdr = phdr_table_; phdr < phdr_limit; ++phdr) {
if (phdr->p_type == PT_PHDR) {
return CheckPhdr(load_bias_ + phdr->p_vaddr);
}
@@ -623,13 +587,13 @@ bool ElfReader::FindPhdr() {
// Otherwise, check the first loadable segment. If its file offset
// is 0, it starts with the ELF header, and we can trivially find the
// loaded program header from it.
for (const Elf32_Phdr* phdr = phdr_table_; phdr < phdr_limit; ++phdr) {
for (const Elf_Phdr* phdr = phdr_table_; phdr < phdr_limit; ++phdr) {
if (phdr->p_type == PT_LOAD) {
if (phdr->p_offset == 0) {
Elf32_Addr elf_addr = load_bias_ + phdr->p_vaddr;
const Elf32_Ehdr* ehdr = (const Elf32_Ehdr*)(void*)elf_addr;
Elf32_Addr offset = ehdr->e_phoff;
return CheckPhdr((Elf32_Addr)ehdr + offset);
Elf_Addr elf_addr = load_bias_ + phdr->p_vaddr;
const Elf_Ehdr* ehdr = (const Elf_Ehdr*)(void*)elf_addr;
Elf_Addr offset = ehdr->e_phoff;
return CheckPhdr((Elf_Addr)ehdr + offset);
}
break;
}
@@ -642,17 +606,17 @@ bool ElfReader::FindPhdr() {
// Ensures that our program header is actually within a loadable
// segment. This should help catch badly-formed ELF files that
// would cause the linker to crash later when trying to access it.
bool ElfReader::CheckPhdr(Elf32_Addr loaded) {
const Elf32_Phdr* phdr_limit = phdr_table_ + phdr_num_;
Elf32_Addr loaded_end = loaded + (phdr_num_ * sizeof(Elf32_Phdr));
for (Elf32_Phdr* phdr = phdr_table_; phdr < phdr_limit; ++phdr) {
bool ElfReader::CheckPhdr(Elf_Addr loaded) {
const Elf_Phdr* phdr_limit = phdr_table_ + phdr_num_;
Elf_Addr loaded_end = loaded + (phdr_num_ * sizeof(Elf_Phdr));
for (Elf_Phdr* phdr = phdr_table_; phdr < phdr_limit; ++phdr) {
if (phdr->p_type != PT_LOAD) {
continue;
}
Elf32_Addr seg_start = phdr->p_vaddr + load_bias_;
Elf32_Addr seg_end = phdr->p_filesz + seg_start;
Elf_Addr seg_start = phdr->p_vaddr + load_bias_;
Elf_Addr seg_end = phdr->p_filesz + seg_start;
if (seg_start <= loaded && loaded_end <= seg_end) {
loaded_phdr_ = reinterpret_cast<const Elf32_Phdr*>(loaded);
loaded_phdr_ = reinterpret_cast<const Elf_Phdr*>(loaded);
return true;
}
}