Runtime can now be set to require relocation
Add a pair of runtime flags -Xrelocate and -Xnorelocate that can force
the runtime to require that all files that are run are relocated, to
prevent attacks based on the known art base address.
Add support for running patchoat on oat files compiled without an image.
Change run-test to have new --prebuild and --relocate flags.
Bug: 15358152
Change-Id: I91166c62dd1ab80e5cbcb7883a2cd0d56afca32d
diff --git a/compiler/elf_patcher.cc b/compiler/elf_patcher.cc
new file mode 100644
index 0000000..6112fbb
--- /dev/null
+++ b/compiler/elf_patcher.cc
@@ -0,0 +1,293 @@
+/*
+ * Copyright (C) 2014 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "elf_patcher.h"
+
+#include <vector>
+#include <set>
+
+#include "elf_file.h"
+#include "elf_utils.h"
+#include "mirror/art_field-inl.h"
+#include "mirror/art_method-inl.h"
+#include "mirror/array-inl.h"
+#include "mirror/class-inl.h"
+#include "mirror/class_loader.h"
+#include "mirror/dex_cache-inl.h"
+#include "mirror/object-inl.h"
+#include "mirror/object_array-inl.h"
+#include "mirror/string-inl.h"
+#include "oat.h"
+#include "os.h"
+#include "utils.h"
+
+namespace art {
+
+bool ElfPatcher::Patch(const CompilerDriver* driver, ElfFile* elf_file,
+ const std::string& oat_location,
+ ImageAddressCallback cb, void* cb_data,
+ std::string* error_msg) {
+ ClassLinker* class_linker = Runtime::Current()->GetClassLinker();
+ const OatFile* oat_file = class_linker->FindOpenedOatFileFromOatLocation(oat_location);
+ if (oat_file == nullptr) {
+ CHECK(Runtime::Current()->IsCompiler());
+ oat_file = OatFile::Open(oat_location, oat_location, NULL, false, error_msg);
+ if (oat_file == nullptr) {
+ *error_msg = StringPrintf("Unable to find or open oat file at '%s': %s", oat_location.c_str(),
+ error_msg->c_str());
+ return false;
+ }
+ CHECK_EQ(class_linker->RegisterOatFile(oat_file), oat_file);
+ }
+ return ElfPatcher::Patch(driver, elf_file, oat_file,
+ reinterpret_cast<uintptr_t>(oat_file->Begin()), cb, cb_data, error_msg);
+}
+
+bool ElfPatcher::Patch(const CompilerDriver* driver, ElfFile* elf, const OatFile* oat_file,
+ uintptr_t oat_data_start, ImageAddressCallback cb, void* cb_data,
+ std::string* error_msg) {
+ Elf32_Shdr* data_sec = elf->FindSectionByName(".rodata");
+ if (data_sec == nullptr) {
+ *error_msg = "Unable to find .rodata section and oat header";
+ return false;
+ }
+ OatHeader* oat_header = reinterpret_cast<OatHeader*>(elf->Begin() + data_sec->sh_offset);
+ if (!oat_header->IsValid()) {
+ *error_msg = "Oat header was not valid";
+ return false;
+ }
+
+ ElfPatcher p(driver, elf, oat_file, oat_header, oat_data_start, cb, cb_data, error_msg);
+ return p.PatchElf();
+}
+
+mirror::ArtMethod* ElfPatcher::GetTargetMethod(const CompilerDriver::CallPatchInformation* patch) {
+ ClassLinker* class_linker = Runtime::Current()->GetClassLinker();
+ StackHandleScope<1> hs(Thread::Current());
+ Handle<mirror::DexCache> dex_cache(
+ hs.NewHandle(class_linker->FindDexCache(*patch->GetTargetDexFile())));
+ mirror::ArtMethod* method = class_linker->ResolveMethod(*patch->GetTargetDexFile(),
+ patch->GetTargetMethodIdx(),
+ dex_cache,
+ NullHandle<mirror::ClassLoader>(),
+ NullHandle<mirror::ArtMethod>(),
+ patch->GetTargetInvokeType());
+ CHECK(method != NULL)
+ << patch->GetTargetDexFile()->GetLocation() << " " << patch->GetTargetMethodIdx();
+ CHECK(!method->IsRuntimeMethod())
+ << patch->GetTargetDexFile()->GetLocation() << " " << patch->GetTargetMethodIdx();
+ CHECK(dex_cache->GetResolvedMethods()->Get(patch->GetTargetMethodIdx()) == method)
+ << patch->GetTargetDexFile()->GetLocation() << " " << patch->GetReferrerMethodIdx() << " "
+ << PrettyMethod(dex_cache->GetResolvedMethods()->Get(patch->GetTargetMethodIdx())) << " "
+ << PrettyMethod(method);
+ return method;
+}
+
+mirror::Class* ElfPatcher::GetTargetType(const CompilerDriver::TypePatchInformation* patch) {
+ ClassLinker* class_linker = Runtime::Current()->GetClassLinker();
+ StackHandleScope<2> hs(Thread::Current());
+ Handle<mirror::DexCache> dex_cache(hs.NewHandle(class_linker->FindDexCache(patch->GetDexFile())));
+ mirror::Class* klass = class_linker->ResolveType(patch->GetDexFile(), patch->GetTargetTypeIdx(),
+ dex_cache, NullHandle<mirror::ClassLoader>());
+ CHECK(klass != NULL)
+ << patch->GetDexFile().GetLocation() << " " << patch->GetTargetTypeIdx();
+ CHECK(dex_cache->GetResolvedTypes()->Get(patch->GetTargetTypeIdx()) == klass)
+ << patch->GetDexFile().GetLocation() << " " << patch->GetReferrerMethodIdx() << " "
+ << PrettyClass(dex_cache->GetResolvedTypes()->Get(patch->GetTargetTypeIdx())) << " "
+ << PrettyClass(klass);
+ return klass;
+}
+
+void ElfPatcher::AddPatch(uintptr_t p) {
+ if (write_patches_ && patches_set_.find(p) == patches_set_.end()) {
+ patches_set_.insert(p);
+ patches_.push_back(p);
+ }
+}
+
+uint32_t* ElfPatcher::GetPatchLocation(uintptr_t patch_ptr) {
+ CHECK_GE(patch_ptr, reinterpret_cast<uintptr_t>(oat_file_->Begin()));
+ uintptr_t off = patch_ptr - reinterpret_cast<uintptr_t>(oat_file_->Begin());
+ uintptr_t ret = reinterpret_cast<uintptr_t>(oat_header_) + off;
+
+ CHECK_GE(ret, reinterpret_cast<uintptr_t>(elf_file_->Begin()));
+ CHECK_LT(ret, reinterpret_cast<uintptr_t>(elf_file_->End()));
+ return reinterpret_cast<uint32_t*>(ret);
+}
+
+void ElfPatcher::SetPatchLocation(const CompilerDriver::PatchInformation* patch, uint32_t value) {
+ ClassLinker* class_linker = Runtime::Current()->GetClassLinker();
+ const void* quick_oat_code = class_linker->GetQuickOatCodeFor(patch->GetDexFile(),
+ patch->GetReferrerClassDefIdx(),
+ patch->GetReferrerMethodIdx());
+ // TODO: make this Thumb2 specific
+ uint8_t* base = reinterpret_cast<uint8_t*>(reinterpret_cast<uintptr_t>(quick_oat_code) & ~0x1);
+ uintptr_t patch_ptr = reinterpret_cast<uintptr_t>(base + patch->GetLiteralOffset());
+ uint32_t* patch_location = GetPatchLocation(patch_ptr);
+ if (kIsDebugBuild) {
+ if (patch->IsCall()) {
+ const CompilerDriver::CallPatchInformation* cpatch = patch->AsCall();
+ const DexFile::MethodId& id =
+ cpatch->GetTargetDexFile()->GetMethodId(cpatch->GetTargetMethodIdx());
+ uint32_t expected = reinterpret_cast<uintptr_t>(&id) & 0xFFFFFFFF;
+ uint32_t actual = *patch_location;
+ CHECK(actual == expected || actual == value) << std::hex
+ << "actual=" << actual
+ << "expected=" << expected
+ << "value=" << value;
+ }
+ if (patch->IsType()) {
+ const CompilerDriver::TypePatchInformation* tpatch = patch->AsType();
+ const DexFile::TypeId& id = tpatch->GetDexFile().GetTypeId(tpatch->GetTargetTypeIdx());
+ uint32_t expected = reinterpret_cast<uintptr_t>(&id) & 0xFFFFFFFF;
+ uint32_t actual = *patch_location;
+ CHECK(actual == expected || actual == value) << std::hex
+ << "actual=" << actual
+ << "expected=" << expected
+ << "value=" << value;
+ }
+ }
+ *patch_location = value;
+ oat_header_->UpdateChecksum(patch_location, sizeof(value));
+
+ if (patch->IsCall() && patch->AsCall()->IsRelative()) {
+ // We never record relative patches.
+ return;
+ }
+ uintptr_t loc = patch_ptr - (reinterpret_cast<uintptr_t>(oat_file_->Begin()) +
+ oat_header_->GetExecutableOffset());
+ CHECK_GT(patch_ptr, reinterpret_cast<uintptr_t>(oat_file_->Begin()) +
+ oat_header_->GetExecutableOffset());
+ CHECK_LT(loc, oat_file_->Size() - oat_header_->GetExecutableOffset());
+ AddPatch(loc);
+}
+
+bool ElfPatcher::PatchElf() {
+ // TODO if we are adding patches the resulting ELF file might have a
+ // potentially rather large amount of free space where patches might have been
+ // placed. We should adjust the ELF file to get rid of this excess space.
+ if (write_patches_) {
+ patches_.reserve(compiler_driver_->GetCodeToPatch().size() +
+ compiler_driver_->GetMethodsToPatch().size() +
+ compiler_driver_->GetClassesToPatch().size());
+ }
+ Thread* self = Thread::Current();
+ ClassLinker* class_linker = Runtime::Current()->GetClassLinker();
+ const char* old_cause = self->StartAssertNoThreadSuspension("ElfPatcher");
+
+ typedef std::vector<const CompilerDriver::CallPatchInformation*> CallPatches;
+ const CallPatches& code_to_patch = compiler_driver_->GetCodeToPatch();
+ for (size_t i = 0; i < code_to_patch.size(); i++) {
+ const CompilerDriver::CallPatchInformation* patch = code_to_patch[i];
+
+ mirror::ArtMethod* target = GetTargetMethod(patch);
+ uintptr_t quick_code = reinterpret_cast<uintptr_t>(class_linker->GetQuickOatCodeFor(target));
+ DCHECK_NE(quick_code, 0U) << PrettyMethod(target);
+ const OatFile* target_oat = class_linker->FindOpenedOatFileForDexFile(*patch->GetTargetDexFile());
+ // Get where the data actually starts. if target is this oat_file_ it is oat_data_start_,
+ // otherwise it is wherever target_oat is loaded.
+ uintptr_t oat_data_addr = GetBaseAddressFor(target_oat);
+ uintptr_t code_base = reinterpret_cast<uintptr_t>(target_oat->Begin());
+ uintptr_t code_offset = quick_code - code_base;
+ bool is_quick_offset = false;
+ if (quick_code == reinterpret_cast<uintptr_t>(GetQuickToInterpreterBridge())) {
+ is_quick_offset = true;
+ code_offset = oat_header_->GetQuickToInterpreterBridgeOffset();
+ } else if (quick_code ==
+ reinterpret_cast<uintptr_t>(class_linker->GetQuickGenericJniTrampoline())) {
+ CHECK(target->IsNative());
+ is_quick_offset = true;
+ code_offset = oat_header_->GetQuickGenericJniTrampolineOffset();
+ }
+ uintptr_t value;
+ if (patch->IsRelative()) {
+ // value to patch is relative to the location being patched
+ const void* quick_oat_code =
+ class_linker->GetQuickOatCodeFor(patch->GetDexFile(),
+ patch->GetReferrerClassDefIdx(),
+ patch->GetReferrerMethodIdx());
+ if (is_quick_offset) {
+ // If its a quick offset it means that we are doing a relative patch from the class linker
+ // oat_file to the elf_patcher oat_file so we need to adjust the quick oat code to be the
+ // one in the output oat_file (ie where it is actually going to be loaded).
+ quick_code = PointerToLowMemUInt32(reinterpret_cast<void*>(oat_data_addr + code_offset));
+ quick_oat_code =
+ reinterpret_cast<const void*>(reinterpret_cast<uintptr_t>(quick_oat_code) +
+ oat_data_addr - code_base);
+ }
+ uintptr_t base = reinterpret_cast<uintptr_t>(quick_oat_code);
+ uintptr_t patch_location = base + patch->GetLiteralOffset();
+ value = quick_code - patch_location + patch->RelativeOffset();
+ } else if (code_offset != 0) {
+ value = PointerToLowMemUInt32(reinterpret_cast<void*>(oat_data_addr + code_offset));
+ } else {
+ value = 0;
+ }
+ SetPatchLocation(patch, value);
+ }
+
+ const CallPatches& methods_to_patch = compiler_driver_->GetMethodsToPatch();
+ for (size_t i = 0; i < methods_to_patch.size(); i++) {
+ const CompilerDriver::CallPatchInformation* patch = methods_to_patch[i];
+ mirror::ArtMethod* target = GetTargetMethod(patch);
+ SetPatchLocation(patch, PointerToLowMemUInt32(get_image_address_(cb_data_, target)));
+ }
+
+ const std::vector<const CompilerDriver::TypePatchInformation*>& classes_to_patch =
+ compiler_driver_->GetClassesToPatch();
+ for (size_t i = 0; i < classes_to_patch.size(); i++) {
+ const CompilerDriver::TypePatchInformation* patch = classes_to_patch[i];
+ mirror::Class* target = GetTargetType(patch);
+ SetPatchLocation(patch, PointerToLowMemUInt32(get_image_address_(cb_data_, target)));
+ }
+
+ self->EndAssertNoThreadSuspension(old_cause);
+
+ if (write_patches_) {
+ return WriteOutPatchData();
+ }
+ return true;
+}
+
+bool ElfPatcher::WriteOutPatchData() {
+ Elf32_Shdr* shdr = elf_file_->FindSectionByName(".oat_patches");
+ if (shdr != nullptr) {
+ CHECK_EQ(shdr, elf_file_->FindSectionByType(SHT_OAT_PATCH))
+ << "Incorrect type for .oat_patches section";
+ CHECK_LE(patches_.size() * sizeof(uintptr_t), shdr->sh_size)
+ << "We got more patches than anticipated";
+ CHECK_LE(reinterpret_cast<uintptr_t>(elf_file_->Begin()) + shdr->sh_offset + shdr->sh_size,
+ reinterpret_cast<uintptr_t>(elf_file_->End())) << "section is too large";
+ CHECK(shdr == &elf_file_->GetSectionHeader(elf_file_->GetSectionHeaderNum() - 1) ||
+ shdr->sh_offset + shdr->sh_size <= (shdr + 1)->sh_offset)
+ << "Section overlaps onto next section";
+ // It's mmap'd so we can just memcpy.
+ memcpy(elf_file_->Begin() + shdr->sh_offset, patches_.data(),
+ patches_.size() * sizeof(uintptr_t));
+ // TODO We should fill in the newly empty space between the last patch and
+ // the start of the next section by moving the following sections down if
+ // possible.
+ shdr->sh_size = patches_.size() * sizeof(uintptr_t);
+ return true;
+ } else {
+ LOG(ERROR) << "Unable to find section header for SHT_OAT_PATCH";
+ *error_msg_ = "Unable to find section to write patch information to in ";
+ *error_msg_ += elf_file_->GetFile().GetPath();
+ return false;
+ }
+}
+
+} // namespace art