llvm-6502/include/llvm/Transforms/Instrumentation.h
Peter Collingbourne 7ffec838a2 Protection against stack-based memory corruption errors using SafeStack
This patch adds the safe stack instrumentation pass to LLVM, which separates
the program stack into a safe stack, which stores return addresses, register
spills, and local variables that are statically verified to be accessed
in a safe way, and the unsafe stack, which stores everything else. Such
separation makes it much harder for an attacker to corrupt objects on the
safe stack, including function pointers stored in spilled registers and
return addresses. You can find more information about the safe stack, as
well as other parts of or control-flow hijack protection technique in our
OSDI paper on code-pointer integrity (http://dslab.epfl.ch/pubs/cpi.pdf)
and our project website (http://levee.epfl.ch).

The overhead of our implementation of the safe stack is very close to zero
(0.01% on the Phoronix benchmarks). This is lower than the overhead of
stack cookies, which are supported by LLVM and are commonly used today,
yet the security guarantees of the safe stack are strictly stronger than
stack cookies. In some cases, the safe stack improves performance due to
better cache locality.

Our current implementation of the safe stack is stable and robust, we
used it to recompile multiple projects on Linux including Chromium, and
we also recompiled the entire FreeBSD user-space system and more than 100
packages. We ran unit tests on the FreeBSD system and many of the packages
and observed no errors caused by the safe stack. The safe stack is also fully
binary compatible with non-instrumented code and can be applied to parts of
a program selectively.

This patch is our implementation of the safe stack on top of LLVM. The
patches make the following changes:

- Add the safestack function attribute, similar to the ssp, sspstrong and
  sspreq attributes.

- Add the SafeStack instrumentation pass that applies the safe stack to all
  functions that have the safestack attribute. This pass moves all unsafe local
  variables to the unsafe stack with a separate stack pointer, whereas all
  safe variables remain on the regular stack that is managed by LLVM as usual.

- Invoke the pass as the last stage before code generation (at the same time
  the existing cookie-based stack protector pass is invoked).

- Add unit tests for the safe stack.

Original patch by Volodymyr Kuznetsov and others at the Dependable Systems
Lab at EPFL; updates and upstreaming by myself.

Differential Revision: http://reviews.llvm.org/D6094

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@239761 91177308-0d34-0410-b5e6-96231b3b80d8
2015-06-15 21:07:11 +00:00

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//===- Transforms/Instrumentation.h - Instrumentation passes ----*- C++ -*-===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file defines constructor functions for instrumentation passes.
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_TRANSFORMS_INSTRUMENTATION_H
#define LLVM_TRANSFORMS_INSTRUMENTATION_H
#include "llvm/ADT/StringRef.h"
#include <vector>
#if defined(__GNUC__) && defined(__linux__) && !defined(ANDROID)
inline void *getDFSanArgTLSPtrForJIT() {
extern __thread __attribute__((tls_model("initial-exec")))
void *__dfsan_arg_tls;
return (void *)&__dfsan_arg_tls;
}
inline void *getDFSanRetValTLSPtrForJIT() {
extern __thread __attribute__((tls_model("initial-exec")))
void *__dfsan_retval_tls;
return (void *)&__dfsan_retval_tls;
}
#endif
namespace llvm {
class ModulePass;
class FunctionPass;
// Insert GCOV profiling instrumentation
struct GCOVOptions {
static GCOVOptions getDefault();
// Specify whether to emit .gcno files.
bool EmitNotes;
// Specify whether to modify the program to emit .gcda files when run.
bool EmitData;
// A four-byte version string. The meaning of a version string is described in
// gcc's gcov-io.h
char Version[4];
// Emit a "cfg checksum" that follows the "line number checksum" of a
// function. This affects both .gcno and .gcda files.
bool UseCfgChecksum;
// Add the 'noredzone' attribute to added runtime library calls.
bool NoRedZone;
// Emit the name of the function in the .gcda files. This is redundant, as
// the function identifier can be used to find the name from the .gcno file.
bool FunctionNamesInData;
// Emit the exit block immediately after the start block, rather than after
// all of the function body's blocks.
bool ExitBlockBeforeBody;
};
ModulePass *createGCOVProfilerPass(const GCOVOptions &Options =
GCOVOptions::getDefault());
/// Options for the frontend instrumentation based profiling pass.
struct InstrProfOptions {
InstrProfOptions() : NoRedZone(false) {}
// Add the 'noredzone' attribute to added runtime library calls.
bool NoRedZone;
// Name of the profile file to use as output
std::string InstrProfileOutput;
};
/// Insert frontend instrumentation based profiling.
ModulePass *createInstrProfilingPass(
const InstrProfOptions &Options = InstrProfOptions());
// Insert AddressSanitizer (address sanity checking) instrumentation
FunctionPass *createAddressSanitizerFunctionPass();
ModulePass *createAddressSanitizerModulePass();
// Insert MemorySanitizer instrumentation (detection of uninitialized reads)
FunctionPass *createMemorySanitizerPass(int TrackOrigins = 0);
// Insert ThreadSanitizer (race detection) instrumentation
FunctionPass *createThreadSanitizerPass();
// Insert DataFlowSanitizer (dynamic data flow analysis) instrumentation
ModulePass *createDataFlowSanitizerPass(
const std::vector<std::string> &ABIListFiles = std::vector<std::string>(),
void *(*getArgTLS)() = nullptr, void *(*getRetValTLS)() = nullptr);
// Options for sanitizer coverage instrumentation.
struct SanitizerCoverageOptions {
SanitizerCoverageOptions()
: CoverageType(SCK_None), IndirectCalls(false), TraceBB(false),
TraceCmp(false), Use8bitCounters(false) {}
enum Type {
SCK_None = 0,
SCK_Function,
SCK_BB,
SCK_Edge
} CoverageType;
bool IndirectCalls;
bool TraceBB;
bool TraceCmp;
bool Use8bitCounters;
};
// Insert SanitizerCoverage instrumentation.
ModulePass *createSanitizerCoverageModulePass(
const SanitizerCoverageOptions &Options = SanitizerCoverageOptions());
#if defined(__GNUC__) && defined(__linux__) && !defined(ANDROID)
inline ModulePass *createDataFlowSanitizerPassForJIT(
const std::vector<std::string> &ABIListFiles = std::vector<std::string>()) {
return createDataFlowSanitizerPass(ABIListFiles, getDFSanArgTLSPtrForJIT,
getDFSanRetValTLSPtrForJIT);
}
#endif
// BoundsChecking - This pass instruments the code to perform run-time bounds
// checking on loads, stores, and other memory intrinsics.
FunctionPass *createBoundsCheckingPass();
/// \brief This pass splits the stack into a safe stack and an unsafe stack to
/// protect against stack-based overflow vulnerabilities.
FunctionPass *createSafeStackPass();
} // End llvm namespace
#endif