0a3637d3eb
Control Flow Integrity support in bionic. General design: http://clang.llvm.org/docs/ControlFlowIntegrityDesign.html#shared-library-support This CL implements subsections "CFI Shadow" and "CFI_SlowPath" in the above document. Bug: 22033465 Test: bionic device tests Change-Id: I14dfea630de468eb5620e7f55f92b1397ba06217
77 lines
2.8 KiB
C++
77 lines
2.8 KiB
C++
/*
|
|
* Copyright (C) 2016 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 <sys/mman.h>
|
|
|
|
#include "private/CFIShadow.h"
|
|
|
|
__attribute__((__weak__, visibility("default"))) extern "C" void __loader_cfi_fail(
|
|
uint64_t CallSiteTypeId, void* Ptr, void* DiagData, void* CallerPc);
|
|
|
|
// Base address of the CFI shadow. Passed down from the linker in __cfi_init()
|
|
// and does not change after that. The contents of the shadow change in
|
|
// dlopen/dlclose.
|
|
static struct {
|
|
uintptr_t v;
|
|
char padding[PAGE_SIZE - sizeof(v)];
|
|
} shadow_base_storage alignas(PAGE_SIZE);
|
|
|
|
extern "C" uintptr_t* __cfi_init(uintptr_t shadow_base) {
|
|
shadow_base_storage.v = shadow_base;
|
|
static_assert(sizeof(shadow_base_storage) == PAGE_SIZE, "");
|
|
mprotect(&shadow_base_storage, PAGE_SIZE, PROT_READ);
|
|
return &shadow_base_storage.v;
|
|
}
|
|
|
|
static uint16_t shadow_load(void* p) {
|
|
uintptr_t addr = reinterpret_cast<uintptr_t>(p);
|
|
uintptr_t ofs = CFIShadow::MemToShadowOffset(addr);
|
|
if (ofs > CFIShadow::kShadowSize) return CFIShadow::kInvalidShadow;
|
|
return *reinterpret_cast<uint16_t*>(shadow_base_storage.v + ofs);
|
|
}
|
|
|
|
static uintptr_t cfi_check_addr(uint16_t v, void* Ptr) {
|
|
uintptr_t addr = reinterpret_cast<uintptr_t>(Ptr);
|
|
uintptr_t aligned_addr = align_up(addr, CFIShadow::kShadowAlign);
|
|
uintptr_t p = aligned_addr - (static_cast<uintptr_t>(v - CFIShadow::kRegularShadowMin)
|
|
<< CFIShadow::kCfiCheckGranularity);
|
|
#ifdef __arm__
|
|
// Assume Thumb encoding. FIXME: force thumb at compile time?
|
|
p++;
|
|
#endif
|
|
return p;
|
|
}
|
|
|
|
static inline void cfi_slowpath_common(uint64_t CallSiteTypeId, void* Ptr, void* DiagData) {
|
|
uint16_t v = shadow_load(Ptr);
|
|
switch (v) {
|
|
case CFIShadow::kInvalidShadow:
|
|
__loader_cfi_fail(CallSiteTypeId, Ptr, DiagData, __builtin_return_address(0));
|
|
break;
|
|
case CFIShadow::kUncheckedShadow:
|
|
break;
|
|
default:
|
|
reinterpret_cast<CFIShadow::CFICheckFn>(cfi_check_addr(v, Ptr))(CallSiteTypeId, Ptr, DiagData);
|
|
}
|
|
}
|
|
|
|
extern "C" void __cfi_slowpath(uint64_t CallSiteTypeId, void* Ptr) {
|
|
cfi_slowpath_common(CallSiteTypeId, Ptr, nullptr);
|
|
}
|
|
|
|
extern "C" void __cfi_slowpath_diag(uint64_t CallSiteTypeId, void* Ptr, void* DiagData) {
|
|
cfi_slowpath_common(CallSiteTypeId, Ptr, DiagData);
|
|
}
|