[compiler-rt] r258859 - [cfi] Hide runtime implementation in a namespace.
Evgeniy Stepanov via llvm-commits
llvm-commits at lists.llvm.org
Tue Jan 26 13:06:26 PST 2016
Author: eugenis
Date: Tue Jan 26 15:06:26 2016
New Revision: 258859
URL: http://llvm.org/viewvc/llvm-project?rev=258859&view=rev
Log:
[cfi] Hide runtime implementation in a namespace.
Move all internal stuff into namespace __cfi.
Remove the double underscore prefix from anything that's now inside
the namespace.
Modified:
compiler-rt/trunk/lib/cfi/cfi.cc
compiler-rt/trunk/test/cfi/cross-dso/shadow_is_read_only.cpp
Modified: compiler-rt/trunk/lib/cfi/cfi.cc
URL: http://llvm.org/viewvc/llvm-project/compiler-rt/trunk/lib/cfi/cfi.cc?rev=258859&r1=258858&r2=258859&view=diff
==============================================================================
--- compiler-rt/trunk/lib/cfi/cfi.cc (original)
+++ compiler-rt/trunk/lib/cfi/cfi.cc Tue Jan 26 15:06:26 2016
@@ -26,13 +26,15 @@ typedef ElfW(Ehdr) Elf_Ehdr;
#include "ubsan/ubsan_init.h"
#include "ubsan/ubsan_flags.h"
+namespace __cfi {
+
static constexpr uptr kCfiShadowPointerStorageSize = 4096; // 1 page
// Lets hope that the data segment is mapped with 4K pages.
// The pointer to the cfi shadow region is stored at the start of this page.
// The rest of the page is unused and re-mapped read-only.
-static char __cfi_shadow_pointer_storage[kCfiShadowPointerStorageSize]
+static char cfi_shadow_pointer_storage[kCfiShadowPointerStorageSize]
__attribute__((aligned(kCfiShadowPointerStorageSize)));
-static uptr __cfi_shadow_size;
+static uptr cfi_shadow_size;
static constexpr uptr kShadowGranularity = 12;
static constexpr uptr kShadowAlign = 1UL << kShadowGranularity; // 4096
@@ -41,10 +43,10 @@ static constexpr uint16_t kUncheckedShad
// Get the start address of the CFI shadow region.
uptr GetShadow() {
- return *reinterpret_cast<uptr *>(&__cfi_shadow_pointer_storage);
+ return *reinterpret_cast<uptr *>(&cfi_shadow_pointer_storage);
}
-static uint16_t *MemToShadow(uptr x, uptr shadow_base) {
+uint16_t *MemToShadow(uptr x, uptr shadow_base) {
return (uint16_t *)(shadow_base + ((x >> kShadowGranularity) << 1));
}
@@ -93,9 +95,8 @@ public:
};
void ShadowBuilder::Start() {
- shadow_ = (uptr)MmapNoReserveOrDie(__cfi_shadow_size, "CFI shadow");
- VReport(1, "CFI: shadow at %zx .. %zx\n", shadow_,
- shadow_ + __cfi_shadow_size);
+ shadow_ = (uptr)MmapNoReserveOrDie(cfi_shadow_size, "CFI shadow");
+ VReport(1, "CFI: shadow at %zx .. %zx\n", shadow_, shadow_ + cfi_shadow_size);
}
void ShadowBuilder::AddUnchecked(uptr begin, uptr end) {
@@ -121,19 +122,19 @@ void ShadowBuilder::Add(uptr begin, uptr
#if SANITIZER_LINUX
void ShadowBuilder::Install() {
- MprotectReadOnly(shadow_, __cfi_shadow_size);
+ MprotectReadOnly(shadow_, cfi_shadow_size);
uptr main_shadow = GetShadow();
if (main_shadow) {
// Update.
- void *res = mremap((void *)shadow_, __cfi_shadow_size, __cfi_shadow_size,
+ void *res = mremap((void *)shadow_, cfi_shadow_size, cfi_shadow_size,
MREMAP_MAYMOVE | MREMAP_FIXED, main_shadow);
CHECK(res != MAP_FAILED);
} else {
// Initial setup.
CHECK_EQ(kCfiShadowPointerStorageSize, GetPageSizeCached());
CHECK_EQ(0, GetShadow());
- *reinterpret_cast<uptr *>(&__cfi_shadow_pointer_storage) = shadow_;
- MprotectReadOnly((uptr)&__cfi_shadow_pointer_storage,
+ *reinterpret_cast<uptr *>(&cfi_shadow_pointer_storage) = shadow_;
+ MprotectReadOnly((uptr)&cfi_shadow_pointer_storage,
kCfiShadowPointerStorageSize);
CHECK_EQ(shadow_, GetShadow());
}
@@ -147,7 +148,7 @@ void ShadowBuilder::Install() {
// Other platforms can, hopefully, just do
// dlopen(RTLD_NOLOAD | RTLD_LAZY)
// dlsym("__cfi_check").
-static uptr find_cfi_check_in_dso(dl_phdr_info *info) {
+uptr find_cfi_check_in_dso(dl_phdr_info *info) {
const ElfW(Dyn) *dynamic = nullptr;
for (int i = 0; i < info->dlpi_phnum; ++i) {
if (info->dlpi_phdr[i].p_type == PT_DYNAMIC) {
@@ -201,7 +202,7 @@ static uptr find_cfi_check_in_dso(dl_phd
return 0;
}
-static int dl_iterate_phdr_cb(dl_phdr_info *info, size_t size, void *data) {
+int dl_iterate_phdr_cb(dl_phdr_info *info, size_t size, void *data) {
uptr cfi_check = find_cfi_check_in_dso(info);
if (cfi_check)
VReport(1, "Module '%s' __cfi_check %zx\n", info->dlpi_name, cfi_check);
@@ -230,29 +231,29 @@ static int dl_iterate_phdr_cb(dl_phdr_in
}
// Init or update shadow for the current set of loaded libraries.
-static void UpdateShadow() {
+void UpdateShadow() {
ShadowBuilder b;
b.Start();
dl_iterate_phdr(dl_iterate_phdr_cb, &b);
b.Install();
}
-static void InitShadow() {
+void InitShadow() {
// No difference, really.
UpdateShadow();
}
-static THREADLOCAL int in_loader;
-static BlockingMutex shadow_update_lock(LINKER_INITIALIZED);
+THREADLOCAL int in_loader;
+BlockingMutex shadow_update_lock(LINKER_INITIALIZED);
-static void EnterLoader() {
+void EnterLoader() {
if (in_loader == 0) {
shadow_update_lock.Lock();
}
++in_loader;
}
-static void ExitLoader() {
+void ExitLoader() {
CHECK(in_loader > 0);
--in_loader;
UpdateShadow();
@@ -261,29 +262,7 @@ static void ExitLoader() {
}
}
-// Setup shadow for dlopen()ed libraries.
-// The actual shadow setup happens after dlopen() returns, which means that
-// a library can not be a target of any CFI checks while its constructors are
-// running. It's unclear how to fix this without some extra help from libc.
-// In glibc, mmap inside dlopen is not interceptable.
-// Maybe a seccomp-bpf filter?
-// We could insert a high-priority constructor into the library, but that would
-// not help with the uninstrumented libraries.
-INTERCEPTOR(void*, dlopen, const char *filename, int flag) {
- EnterLoader();
- void *handle = REAL(dlopen)(filename, flag);
- ExitLoader();
- return handle;
-}
-
-INTERCEPTOR(int, dlclose, void *handle) {
- EnterLoader();
- int res = REAL(dlclose)(handle);
- ExitLoader();
- return res;
-}
-
-static ALWAYS_INLINE void CfiSlowPathCommon(u64 CallSiteTypeId, void *Ptr,
+ALWAYS_INLINE void CfiSlowPathCommon(u64 CallSiteTypeId, void *Ptr,
void *DiagData) {
uptr Addr = (uptr)Ptr;
VReport(3, "__cfi_slowpath: %llx, %p\n", CallSiteTypeId, Ptr);
@@ -307,17 +286,7 @@ static ALWAYS_INLINE void CfiSlowPathCom
cfi_check(CallSiteTypeId, Ptr, DiagData);
}
-extern "C" SANITIZER_INTERFACE_ATTRIBUTE void
-__cfi_slowpath(u64 CallSiteTypeId, void *Ptr) {
- CfiSlowPathCommon(CallSiteTypeId, Ptr, nullptr);
-}
-
-extern "C" SANITIZER_INTERFACE_ATTRIBUTE void
-__cfi_slowpath_diag(u64 CallSiteTypeId, void *Ptr, void *DiagData) {
- CfiSlowPathCommon(CallSiteTypeId, Ptr, DiagData);
-}
-
-static void InitializeFlags() {
+void InitializeFlags() {
SetCommonFlagsDefaults();
#ifdef CFI_ENABLE_DIAG
__ubsan::Flags *uf = __ubsan::flags();
@@ -347,6 +316,42 @@ static void InitializeFlags() {
}
}
+} // namespace __cfi
+
+using namespace __cfi;
+
+extern "C" SANITIZER_INTERFACE_ATTRIBUTE void
+__cfi_slowpath(u64 CallSiteTypeId, void *Ptr) {
+ CfiSlowPathCommon(CallSiteTypeId, Ptr, nullptr);
+}
+
+extern "C" SANITIZER_INTERFACE_ATTRIBUTE void
+__cfi_slowpath_diag(u64 CallSiteTypeId, void *Ptr, void *DiagData) {
+ CfiSlowPathCommon(CallSiteTypeId, Ptr, DiagData);
+}
+
+// Setup shadow for dlopen()ed libraries.
+// The actual shadow setup happens after dlopen() returns, which means that
+// a library can not be a target of any CFI checks while its constructors are
+// running. It's unclear how to fix this without some extra help from libc.
+// In glibc, mmap inside dlopen is not interceptable.
+// Maybe a seccomp-bpf filter?
+// We could insert a high-priority constructor into the library, but that would
+// not help with the uninstrumented libraries.
+INTERCEPTOR(void*, dlopen, const char *filename, int flag) {
+ EnterLoader();
+ void *handle = REAL(dlopen)(filename, flag);
+ ExitLoader();
+ return handle;
+}
+
+INTERCEPTOR(int, dlclose, void *handle) {
+ EnterLoader();
+ int res = REAL(dlclose)(handle);
+ ExitLoader();
+ return res;
+}
+
extern "C" SANITIZER_INTERFACE_ATTRIBUTE
#if !SANITIZER_CAN_USE_PREINIT_ARRAY
// On ELF platforms, the constructor is invoked using .preinit_array (see below)
@@ -358,8 +363,8 @@ void __cfi_init() {
uptr vma = GetMaxVirtualAddress();
// Shadow is 2 -> 2**kShadowGranularity.
- __cfi_shadow_size = (vma >> (kShadowGranularity - 1)) + 1;
- VReport(1, "CFI: VMA size %zx, shadow size %zx\n", vma, __cfi_shadow_size);
+ cfi_shadow_size = (vma >> (kShadowGranularity - 1)) + 1;
+ VReport(1, "CFI: VMA size %zx, shadow size %zx\n", vma, cfi_shadow_size);
InitShadow();
Modified: compiler-rt/trunk/test/cfi/cross-dso/shadow_is_read_only.cpp
URL: http://llvm.org/viewvc/llvm-project/compiler-rt/trunk/test/cfi/cross-dso/shadow_is_read_only.cpp?rev=258859&r1=258858&r2=258859&view=diff
==============================================================================
--- compiler-rt/trunk/test/cfi/cross-dso/shadow_is_read_only.cpp (original)
+++ compiler-rt/trunk/test/cfi/cross-dso/shadow_is_read_only.cpp Tue Jan 26 15:06:26 2016
@@ -33,10 +33,13 @@ extern "C" A *create_A() { return new A(
#else
constexpr unsigned kShadowGranularity = 12;
+
+namespace __cfi {
uintptr_t GetShadow();
+}
void write_shadow(void *ptr) {
- uintptr_t base = GetShadow();
+ uintptr_t base = __cfi::GetShadow();
uint16_t *s =
(uint16_t *)(base + (((uintptr_t)ptr >> kShadowGranularity) << 1));
fprintf(stderr, "going to crash\n");
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