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-rw-r--r--linker/linker_phdr.cpp69
1 files changed, 49 insertions, 20 deletions
diff --git a/linker/linker_phdr.cpp b/linker/linker_phdr.cpp
index 4b1c0ca..638c9d6 100644
--- a/linker/linker_phdr.cpp
+++ b/linker/linker_phdr.cpp
@@ -29,7 +29,7 @@
#include "linker_phdr.h"
#include <errno.h>
-#include <machine/exec.h>
+#include <string.h>
#include <sys/mman.h>
#include <sys/types.h>
#include <sys/stat.h>
@@ -38,6 +38,20 @@
#include "linker.h"
#include "linker_debug.h"
+static int GetTargetElfMachine() {
+#if defined(__arm__)
+ return EM_ARM;
+#elif defined(__aarch64__)
+ return EM_AARCH64;
+#elif defined(__i386__)
+ return EM_386;
+#elif defined(__mips__)
+ return EM_MIPS;
+#elif defined(__x86_64__)
+ return EM_X86_64;
+#endif
+}
+
/**
TECHNICAL NOTE ON ELF LOADING.
@@ -200,7 +214,7 @@ bool ElfReader::VerifyElfHeader() {
return false;
}
- if (header_.e_machine != ELF_TARG_MACH) {
+ if (header_.e_machine != GetTargetElfMachine()) {
DL_ERR("\"%s\" has unexpected e_machine: %d", name_, header_.e_machine);
return false;
}
@@ -226,7 +240,8 @@ bool ElfReader::ReadProgramHeader() {
phdr_size_ = page_max - page_min;
- void* mmap_result = mmap64(nullptr, phdr_size_, PROT_READ, MAP_PRIVATE, fd_, file_offset_ + page_min);
+ void* mmap_result =
+ mmap64(nullptr, phdr_size_, PROT_READ, MAP_PRIVATE, fd_, file_offset_ + page_min);
if (mmap_result == MAP_FAILED) {
DL_ERR("\"%s\" phdr mmap failed: %s", name_, strerror(errno));
return false;
@@ -318,7 +333,7 @@ bool ElfReader::ReserveAddressSpace(const android_dlextinfo* extinfo) {
return false;
}
int mmap_flags = MAP_PRIVATE | MAP_ANONYMOUS;
- start = mmap(addr, load_size_, PROT_NONE, mmap_flags, -1, 0);
+ start = mmap(nullptr, load_size_, PROT_NONE, mmap_flags, -1, 0);
if (start == MAP_FAILED) {
DL_ERR("couldn't reserve %zd bytes of address space for \"%s\"", load_size_, name_);
return false;
@@ -414,9 +429,15 @@ static int _phdr_table_set_load_prot(const ElfW(Phdr)* phdr_table, size_t phdr_c
ElfW(Addr) seg_page_start = PAGE_START(phdr->p_vaddr) + load_bias;
ElfW(Addr) seg_page_end = PAGE_END(phdr->p_vaddr + phdr->p_memsz) + load_bias;
+ int prot = PFLAGS_TO_PROT(phdr->p_flags);
+ if ((extra_prot_flags & PROT_WRITE) != 0) {
+ // make sure we're never simultaneously writable / executable
+ prot &= ~PROT_EXEC;
+ }
+
int ret = mprotect(reinterpret_cast<void*>(seg_page_start),
seg_page_end - seg_page_start,
- PFLAGS_TO_PROT(phdr->p_flags) | extra_prot_flags);
+ prot | extra_prot_flags);
if (ret < 0) {
return -1;
}
@@ -435,7 +456,8 @@ static int _phdr_table_set_load_prot(const ElfW(Phdr)* phdr_table, size_t phdr_c
* Return:
* 0 on error, -1 on failure (error code in errno).
*/
-int phdr_table_protect_segments(const ElfW(Phdr)* phdr_table, size_t phdr_count, ElfW(Addr) load_bias) {
+int phdr_table_protect_segments(const ElfW(Phdr)* phdr_table,
+ size_t phdr_count, ElfW(Addr) load_bias) {
return _phdr_table_set_load_prot(phdr_table, phdr_count, load_bias, 0);
}
@@ -455,7 +477,8 @@ int phdr_table_protect_segments(const ElfW(Phdr)* phdr_table, size_t phdr_count,
* Return:
* 0 on error, -1 on failure (error code in errno).
*/
-int phdr_table_unprotect_segments(const ElfW(Phdr)* phdr_table, size_t phdr_count, ElfW(Addr) load_bias) {
+int phdr_table_unprotect_segments(const ElfW(Phdr)* phdr_table,
+ size_t phdr_count, ElfW(Addr) load_bias) {
return _phdr_table_set_load_prot(phdr_table, phdr_count, load_bias, PROT_WRITE);
}
@@ -517,7 +540,8 @@ static int _phdr_table_set_gnu_relro_prot(const ElfW(Phdr)* phdr_table, size_t p
* Return:
* 0 on error, -1 on failure (error code in errno).
*/
-int phdr_table_protect_gnu_relro(const ElfW(Phdr)* phdr_table, size_t phdr_count, ElfW(Addr) load_bias) {
+int phdr_table_protect_gnu_relro(const ElfW(Phdr)* phdr_table,
+ size_t phdr_count, ElfW(Addr) load_bias) {
return _phdr_table_set_gnu_relro_prot(phdr_table, phdr_count, load_bias, PROT_READ);
}
@@ -533,7 +557,9 @@ int phdr_table_protect_gnu_relro(const ElfW(Phdr)* phdr_table, size_t phdr_count
* Return:
* 0 on error, -1 on failure (error code in errno).
*/
-int phdr_table_serialize_gnu_relro(const ElfW(Phdr)* phdr_table, size_t phdr_count, ElfW(Addr) load_bias,
+int phdr_table_serialize_gnu_relro(const ElfW(Phdr)* phdr_table,
+ size_t phdr_count,
+ ElfW(Addr) load_bias,
int fd) {
const ElfW(Phdr)* phdr = phdr_table;
const ElfW(Phdr)* phdr_limit = phdr + phdr_count;
@@ -578,7 +604,9 @@ int phdr_table_serialize_gnu_relro(const ElfW(Phdr)* phdr_table, size_t phdr_cou
* Return:
* 0 on error, -1 on failure (error code in errno).
*/
-int phdr_table_map_gnu_relro(const ElfW(Phdr)* phdr_table, size_t phdr_count, ElfW(Addr) load_bias,
+int phdr_table_map_gnu_relro(const ElfW(Phdr)* phdr_table,
+ size_t phdr_count,
+ ElfW(Addr) load_bias,
int fd) {
// Map the file at a temporary location so we can compare its contents.
struct stat file_stat;
@@ -675,7 +703,7 @@ int phdr_table_map_gnu_relro(const ElfW(Phdr)* phdr_table, size_t phdr_count, El
*/
int phdr_table_get_arm_exidx(const ElfW(Phdr)* phdr_table, size_t phdr_count,
ElfW(Addr) load_bias,
- ElfW(Addr)** arm_exidx, unsigned* arm_exidx_count) {
+ ElfW(Addr)** arm_exidx, size_t* arm_exidx_count) {
const ElfW(Phdr)* phdr = phdr_table;
const ElfW(Phdr)* phdr_limit = phdr + phdr_count;
@@ -685,7 +713,7 @@ int phdr_table_get_arm_exidx(const ElfW(Phdr)* phdr_table, size_t phdr_count,
}
*arm_exidx = reinterpret_cast<ElfW(Addr)*>(load_bias + phdr->p_vaddr);
- *arm_exidx_count = (unsigned)(phdr->p_memsz / 8);
+ *arm_exidx_count = phdr->p_memsz / 8;
return 0;
}
*arm_exidx = nullptr;
@@ -711,20 +739,21 @@ void phdr_table_get_dynamic_section(const ElfW(Phdr)* phdr_table, size_t phdr_co
ElfW(Addr) load_bias, ElfW(Dyn)** dynamic,
ElfW(Word)* dynamic_flags) {
*dynamic = nullptr;
- for (const ElfW(Phdr)* phdr = phdr_table, *phdr_limit = phdr + phdr_count; phdr < phdr_limit; phdr++) {
- if (phdr->p_type == PT_DYNAMIC) {
- *dynamic = reinterpret_cast<ElfW(Dyn)*>(load_bias + phdr->p_vaddr);
+ for (size_t i = 0; i<phdr_count; ++i) {
+ const ElfW(Phdr)& phdr = phdr_table[i];
+ if (phdr.p_type == PT_DYNAMIC) {
+ *dynamic = reinterpret_cast<ElfW(Dyn)*>(load_bias + phdr.p_vaddr);
if (dynamic_flags) {
- *dynamic_flags = phdr->p_flags;
+ *dynamic_flags = phdr.p_flags;
}
return;
}
}
}
-// Returns the address of the program header table as it appears in the loaded
-// segments in memory. This is in contrast with 'phdr_table_' which
-// is temporary and will be released before the library is relocated.
+// Sets loaded_phdr_ to the address of the program header table as it appears
+// in the loaded 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 ElfW(Phdr)* phdr_limit = phdr_table_ + phdr_num_;
@@ -744,7 +773,7 @@ bool ElfReader::FindPhdr() {
ElfW(Addr) elf_addr = load_bias_ + phdr->p_vaddr;
const ElfW(Ehdr)* ehdr = reinterpret_cast<const ElfW(Ehdr)*>(elf_addr);
ElfW(Addr) offset = ehdr->e_phoff;
- return CheckPhdr((ElfW(Addr))ehdr + offset);
+ return CheckPhdr(reinterpret_cast<ElfW(Addr)>(ehdr) + offset);
}
break;
}
generated by cgit v1.1 at 2024-12-22 13:15:54 +0000