Add simple runtime tests for shadowcallstack

[vlad.tsyrklevich]

Summary

ShadowCallStack does not yet have a runtime provided by compiler-rt, but
this change includes simple tests that make use of a very minimal
runtime in test/shadowcallstack/minimal_runtime.h

[kubamracek]

CC'ing some more sanitizer folks. This is the first time I hear about this. Is there some document or a high-level overview of what this is doing?

[vlad.tsyrklevich]

In D44803#1046067, @kubamracek wrote:

CC'ing some more sanitizer folks. This is the first time I hear about this. Is there some document or a high-level overview of what this is doing?

There's a short doc in https://reviews.llvm.org/D44801. It's still experimental, we'd like to gather more performance info to evaluate it.

[pcc]

LGTM

test/CMakeLists.txt

if(COMPILER_RT_BUILD_SANITIZERS)
     endforeach()
   endif()
   if(COMPILER_RT_BUILD_PROFILE AND COMPILER_RT_HAS_PROFILE)
     compiler_rt_test_runtime(profile)
   endif()
   if(COMPILER_RT_BUILD_XRAY)
     compiler_rt_test_runtime(xray)
   endif()
+  # ShadowCallStack does not yet provide a runtime with compiler-rt, the tests
+  # include their own minimal runtime
+  add_subdirectory(shadowcallstack)
 endif()
 
 if(COMPILER_RT_STANDALONE_BUILD)
   # Now that we've traversed all the directories and know all the lit testsuites,
   # introduce a rule to run to run all of them.
   get_property(LLVM_LIT_TESTSUITES GLOBAL PROPERTY LLVM_LIT_TESTSUITES)
   get_property(LLVM_LIT_DEPENDS GLOBAL PROPERTY LLVM_LIT_DEPENDS)
   add_lit_target(check-compiler-rt

test/shadowcallstack/CMakeLists.txt

+set(SHADOWCALLSTACK_LIT_SOURCE_DIR ${CMAKE_CURRENT_SOURCE_DIR})
+set(SHADOWCALLSTACK_LIT_BINARY_DIR ${CMAKE_CURRENT_BINARY_DIR})
+
+set(SHADOWCALLSTACK_TEST_DEPS ${SANITIZER_COMMON_LIT_TEST_DEPS})
+
+configure_lit_site_cfg(
+  ${CMAKE_CURRENT_SOURCE_DIR}/lit.site.cfg.in
+  ${CMAKE_CURRENT_BINARY_DIR}/lit.site.cfg
+  )
+
+add_lit_testsuite(check-shadowcallstack "Running the ShadowCallStack tests"
+  ${CMAKE_CURRENT_BINARY_DIR})
+set_target_properties(check-shadowcallstack PROPERTIES FOLDER "Compiler-RT Misc")

test/shadowcallstack/init.c

+// RUN: %clang_scs -D INCLUDE_RUNTIME %s -o %t
+// RUN: %run %t
+
+// RUN: %clang_scs %s -o %t
+// RUN: not --crash %run %t
+
+// Basic smoke test for the runtime
+
+#ifdef INCLUDE_RUNTIME
+#include "minimal_runtime.h"
+#endif
+
+int main(int argc, char **argv)
+{
+  return 0;
+}

test/shadowcallstack/lit.cfg

+# -*- Python -*-
+
+import os
+
+# Setup config name.
+config.name = 'ShadowCallStack'
+
+# Setup source root.
+config.test_source_root = os.path.dirname(__file__)
+
+# Test suffixes.
+config.suffixes = ['.c', '.cc', '.cpp', '.m', '.mm', '.ll', '.test']
+
+# Add clang substitutions.
+config.substitutions.append( ("%clang_noscs ", config.clang + " -O0 -fno-sanitize=shadow-call-stack ") )
+config.substitutions.append( ("%clang_scs ", config.clang + " -O0 -fsanitize=shadow-call-stack ") )
+
+if config.host_os not in ['Linux'] or config.target_arch != 'x86_64':
+   config.unsupported = True

test/shadowcallstack/lit.site.cfg.in

+@LIT_SITE_CFG_IN_HEADER@
+
+# Load common config for all compiler-rt lit tests.
+lit_config.load_config(config, "@COMPILER_RT_BINARY_DIR@/test/lit.common.configured")
+
+# Load tool-specific config that would do the real work.
+lit_config.load_config(config, "@SHADOWCALLSTACK_LIT_SOURCE_DIR@/lit.cfg")

test/shadowcallstack/minimal_runtime.h

+// A shadow call stack runtime is not yet included with compiler-rt, provide a
+// minimal runtime to allocate a shadow call stack and assign %gs to point at
+// it.
+
+#pragma once
+
+#include <asm/prctl.h>
+#include <stdlib.h>
+#include <sys/mman.h>
+#include <sys/prctl.h>
+
+int arch_prctl(int code, void *addr);
+
+__attribute__((no_sanitize("shadow-call-stack")))
+static void __shadowcallstack_init() {
+  void *stack = mmap(NULL, 8192, PROT_READ | PROT_WRITE,
+                     MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
+  if (stack == MAP_FAILED)
+    abort();
+
+  if (arch_prctl(ARCH_SET_GS, stack))
+    abort();
+}
+
+__attribute__((section(".preinit_array"), used))
+    void (*__shadowcallstack_preinit)(void) = __shadowcallstack_init;

test/shadowcallstack/overflow.c

+// RUN: %clang_noscs %s -o %t
+// RUN: %run %t 3 | FileCheck %s
+// RUN: %run %t 12 | FileCheck -check-prefix=OVERFLOW_SUCCESS %s
+
+// RUN: %clang_scs %s -o %t
+// RUN: %run %t 3 | FileCheck %s
+// RUN: not --crash %run %t 12
+
+// Test that a stack overflow fails as expected
+
+#include <stdio.h>
+#include <stdlib.h>
+
+#include "minimal_runtime.h"
+
+void print_and_exit(void) {
+// CHECK-NOT: Stack overflow successful.
+// OVERFLOW_SUCCESS: Stack overflow successful.
+  printf("Stack overflow successful.\n");
+  exit(0);
+}
+
+int main(int argc, char **argv)
+{
+  if (argc != 2)
+    exit(1);
+
+  void *addrs[4];
+  const int iterations = atoi(argv[1]);
+  for (int i = 0; i < iterations; i++)
+    addrs[i] = &print_and_exit;
+
+  printf("Returning.\n");
+
+  return 0;
+}