Add misc hardening flags to the cmake machinery

See https://wiki.debian.org/Hardening#User_Space

CMakeLists.txt

@@ -27,6 +27,13 @@
 # THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 #
 # Parts of this file are originally copyright (c) 2012-2013 The Cryptonote developers
+list(INSERT CMAKE_MODULE_PATH 0
+  "${CMAKE_SOURCE_DIR}/cmake")
+include(CheckCCompilerFlag)
+include(CheckCXXCompilerFlag)
+include(CheckLinkerFlag)
+include(CheckLibraryExists)
+
 if (IOS)
     INCLUDE(CmakeLists_IOS.txt)
 endif()
@@ -48,6 +55,31 @@ function (die msg)
   message(FATAL_ERROR "${BoldRed}${msg}${ColourReset}")
 endfunction ()
 
+function (add_c_flag_if_supported flag var)
+  string(REPLACE "-" "_" supported ${flag}_c)
+  check_c_compiler_flag(${flag} ${supported})
+  if(${${supported}})
+    set(${var} "${${var}} ${flag}" PARENT_SCOPE)
+  endif()
+endfunction()
+
+function (add_cxx_flag_if_supported flag var)
+  string(REPLACE "-" "_" supported ${flag}_cxx)
+  check_cxx_compiler_flag(${flag} ${supported})
+  if(${${supported}})
+    set(${var} "${${var}} ${flag}" PARENT_SCOPE)
+  endif()
+endfunction()
+
+function (add_linker_flag_if_supported flag var)
+  string(REPLACE "-" "_" supported ${flag}_ld)
+  string(REPLACE "," "_" supported ${flag}_ld)
+  check_linker_flag(${flag} ${supported})
+  if(${${supported}})
+    set(${var} "${${var}} ${flag}" PARENT_SCOPE)
+  endif()
+endfunction()
+
 if(NOT CMAKE_BUILD_TYPE)
   set(CMAKE_BUILD_TYPE Release CACHE STRING "Build type" FORCE)
   message(STATUS "Setting default build type: ${CMAKE_BUILD_TYPE}")
@@ -210,11 +242,11 @@ endif()
 
 if (BUILD_SHARED_LIBS)
   message(STATUS "Building internal libraries with position independent code")
-  set(PIC_FLAG "-fPIC")
   add_definitions("-DBUILD_SHARED_LIBS")
 else()
   message(STATUS "Building internal libraries as static")
 endif()
+set(PIC_FLAG "-fPIC")
 
 if(MINGW)
   string(REGEX MATCH "^[^/]:/[^/]*" msys2_install_path "${CMAKE_C_COMPILER}")
@@ -470,6 +502,52 @@ else()
   set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -fno-strict-aliasing")
   set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -fno-strict-aliasing")
 
+  # if those don't work for your compiler, single it out where appropriate
+  if(CMAKE_BUILD_TYPE STREQUAL "Release")
+    set(C_SECURITY_FLAGS "${C_SECURITY_FLAGS} -U_FORTIFY_SOURCE -D_FORTIFY_SOURCE=1")
+    set(CXX_SECURITY_FLAGS "${CXX_SECURITY_FLAGS} -U_FORTIFY_SOURCE -D_FORTIFY_SOURCE=1")
+  endif()
+
+  # warnings
+  add_c_flag_if_supported(-Wformat C_SECURITY_FLAGS)
+  add_cxx_flag_if_supported(-Wformat CXX_SECURITY_FLAGS)
+  add_c_flag_if_supported(-Wformat-security C_SECURITY_FLAGS)
+  add_cxx_flag_if_supported(-Wformat-security CXX_SECURITY_FLAGS)
+
+  # -fstack-protector
+  add_c_flag_if_supported(-fstack-protector C_SECURITY_FLAGS)
+  add_cxx_flag_if_supported(-fstack-protector CXX_SECURITY_FLAGS)
+  add_c_flag_if_supported(-fstack-protector-strong C_SECURITY_FLAGS)
+  add_cxx_flag_if_supported(-fstack-protector-strong CXX_SECURITY_FLAGS)
+
+  # linker
+  if (NOT WIN32)
+    # Windows binaries die on startup with PIE
+    add_linker_flag_if_supported(-pie LD_SECURITY_FLAGS)
+  endif()
+  add_linker_flag_if_supported(-Wl,-z,relro LD_SECURITY_FLAGS)
+  add_linker_flag_if_supported(-Wl,-z,now LD_SECURITY_FLAGS)
+  add_linker_flag_if_supported(-Wl,-z,noexecstack noexecstack_SUPPORTED)
+  if (noexecstack_SUPPORTED)
+    set(LD_SECURITY_FLAGS "${LD_SECURITY_FLAGS} -Wl,-z,noexecstack")
+    set(LD_RAW_FLAGS ${LD_RAW_FLAGS} -z noexecstack)
+  endif()
+  add_linker_flag_if_supported(-Wl,-z,noexecheap noexecheap_SUPPORTED)
+  if (noexecheap_SUPPORTED)
+    set(LD_SECURITY_FLAGS "${LD_SECURITY_FLAGS} -Wl,-z,noexecheap")
+    set(LD_RAW_FLAGS ${LD_RAW_FLAGS} -z noexecheap)
+  endif()
+
+  # some windows linker bits
+  if (WIN32)
+    add_linker_flag_if_supported(-Wl,--dynamicbase LD_SECURITY_FLAGS)
+    add_linker_flag_if_supported(-Wl,--nxcompat LD_SECURITY_FLAGS)
+  endif()
+
+  message(STATUS "Using C security hardening flags: ${C_SECURITY_FLAGS}")
+  message(STATUS "Using C++ security hardening flags: ${CXX_SECURITY_FLAGS}")
+  message(STATUS "Using linker security hardening flags: ${LD_SECURITY_FLAGS}")
+
   option(NO_AES "Explicitly disable AES support" ${NO_AES})
 
   if(NO_AES)
@@ -498,8 +576,9 @@ else()
     message(STATUS "AES support disabled")
   endif()
 
-  set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -std=c11 -D_GNU_SOURCE ${MINGW_FLAG} ${STATIC_ASSERT_FLAG} ${WARNINGS} ${C_WARNINGS} ${ARCH_FLAG} ${COVERAGE_FLAGS} ${PIC_FLAG}")
+  set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -std=c11 -D_GNU_SOURCE ${MINGW_FLAG} ${STATIC_ASSERT_FLAG} ${WARNINGS} ${C_WARNINGS} ${ARCH_FLAG} ${COVERAGE_FLAGS} ${PIC_FLAG} ${C_SECURITY_FLAGS}")
-  set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -std=c++11 -D_GNU_SOURCE ${MINGW_FLAG} ${STATIC_ASSERT_CPP_FLAG} ${WARNINGS} ${CXX_WARNINGS} ${ARCH_FLAG} ${COVERAGE_FLAGS} ${PIC_FLAG}")
+  set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -std=c++11 -D_GNU_SOURCE ${MINGW_FLAG} ${STATIC_ASSERT_CPP_FLAG} ${WARNINGS} ${CXX_WARNINGS} ${ARCH_FLAG} ${COVERAGE_FLAGS} ${PIC_FLAG} ${CXX_SECURITY_FLAGS}")
+  set(CMAKE_EXE_LINKER_FLAGS "${CMAKE_EXE_LINKER_FLAGS} ${LD_SECURITY_FLAGS}")
 
   # With GCC 6.1.1 the compiled binary malfunctions due to aliasing. Until that
   # is fixed in the code (Issue #847), force compiler to be conservative.
@@ -586,6 +665,7 @@ else()
   if(ANDROID AND NOT BUILD_GUI_DEPS STREQUAL "ON" OR IOS)
     #From Android 5: "only position independent executables (PIE) are supported" 
     message(STATUS "Enabling PIE executable")
+    set(PIC_FLAG "")
     set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -fPIE")
     set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -fPIE")
     set(CMAKE_EXE_LINKER_FLAGS "${CMAKE_CXX_FLAGS} -fPIE -pie")
@@ -778,11 +858,7 @@ option(BUILD_GUI_DEPS "Build GUI dependencies." OFF)
 option(INSTALL_VENDORED_LIBUNBOUND "Install libunbound binary built from source vendored with this repo." OFF)
 
 
-include(CheckCCompilerFlag)
-
 CHECK_C_COMPILER_FLAG(-std=c11 HAVE_C11)
 
-include(CheckLibraryExists)
-
 check_library_exists(c memset_s "string.h" HAVE_MEMSET_S)
 check_library_exists(c explicit_bzero "strings.h" HAVE_EXPLICIT_BZERO)

cmake/CheckLinkerFlag.c

@@ -0,0 +1,14 @@
+#ifdef __CLASSIC_C__
+int main()
+{
+  int ac;
+  char* av[];
+#else
+int main(int ac, char* av[])
+{
+#endif
+  if (ac > 1000) {
+    return *av[0];
+  }
+  return 0;
+}

cmake/CheckLinkerFlag.cmake

@@ -0,0 +1,47 @@
+include(CheckCCompilerFlag)
+
+macro(CHECK_LINKER_FLAG flag VARIABLE)
+  if(NOT DEFINED "${VARIABLE}")
+    if(NOT CMAKE_REQUIRED_QUIET)
+      message(STATUS "Looking for ${flag} linker flag")
+    endif()
+
+    set(_cle_source ${CMAKE_SOURCE_DIR}/cmake/CheckLinkerFlag.c)
+
+    set(saved_CMAKE_C_FLAGS ${CMAKE_C_FLAGS})
+    set(CMAKE_C_FLAGS "${flag}")
+    try_compile(${VARIABLE}
+      ${CMAKE_BINARY_DIR}
+      ${_cle_source}
+      COMPILE_DEFINITIONS ${CMAKE_REQUIRED_DEFINITIONS} ${flag}
+      CMAKE_FLAGS
+      OUTPUT_VARIABLE OUTPUT)
+    unset(_cle_source)
+    set(CMAKE_C_FLAGS ${saved_CMAKE_C_FLAGS})
+    unset(saved_CMAKE_C_FLAGS)
+
+    if ("${OUTPUT}" MATCHES "warning.*ignored")
+      set(${VARIABLE} 0)
+    endif()
+
+    if(${VARIABLE})
+      if(NOT CMAKE_REQUIRED_QUIET)
+        message(STATUS "Looking for ${flag} linker flag - found")
+      endif()
+      set(${VARIABLE} 1 CACHE INTERNAL "Have linker flag ${flag}")
+      file(APPEND ${CMAKE_BINARY_DIR}${CMAKE_FILES_DIRECTORY}/CMakeOutput.log
+        "Determining if the ${flag} linker flag is supported "
+        "passed with the following output:\n"
+        "${OUTPUT}\n\n")
+    else()
+      if(NOT CMAKE_REQUIRED_QUIET)
+        message(STATUS "Looking for ${flag} linker flag - not found")
+      endif()
+      set(${VARIABLE} "" CACHE INTERNAL "Have linker flag ${flag}")
+      file(APPEND ${CMAKE_BINARY_DIR}${CMAKE_FILES_DIRECTORY}/CMakeError.log
+        "Determining if the ${flag} linker flag is suppored "
+        "failed with the following output:\n"
+        "${OUTPUT}\n\n")
+    endif()
+  endif()
+endmacro()

external/db_drivers/liblmdb/CMakeLists.txt

@@ -54,3 +54,4 @@ if(${ARCH_WIDTH} EQUAL 32)
   target_compile_definitions(lmdb
     PUBLIC -DMDB_VL32)
 endif()
+set_property(TARGET lmdb APPEND PROPERTY COMPILE_FLAGS "-fPIC")

external/easylogging++/CMakeLists.txt

@@ -54,4 +54,5 @@ if (BUILD_GUI_DEPS)
         ARCHIVE DESTINATION ${lib_folder}
         LIBRARY DESTINATION ${lib_folder})
 endif()
+set_property(TARGET easylogging APPEND PROPERTY COMPILE_FLAGS "-fPIC")
 

src/blockchain_utilities/CMakeLists.txt

@@ -29,9 +29,9 @@
 set(blocksdat "")
 if(PER_BLOCK_CHECKPOINT)
   if(APPLE)
-    add_custom_command(OUTPUT blocksdat.o MAIN_DEPENDENCY ../blocks/checkpoints.dat COMMAND cd ${CMAKE_CURRENT_SOURCE_DIR} && touch stub.c && ${CMAKE_C_COMPILER} -o stub.o -c stub.c COMMAND cd ${CMAKE_CURRENT_SOURCE_DIR} && ${CMAKE_LINKER} -r -sectcreate __DATA __blocks_dat ../blocks/checkpoints.dat -o ${CMAKE_CURRENT_BINARY_DIR}/blocksdat.o stub.o && rm -f stub.*)
+    add_custom_command(OUTPUT blocksdat.o MAIN_DEPENDENCY ../blocks/checkpoints.dat COMMAND cd ${CMAKE_CURRENT_SOURCE_DIR} && touch stub.c && ${CMAKE_C_COMPILER} -o stub.o -c stub.c COMMAND cd ${CMAKE_CURRENT_SOURCE_DIR} && ${CMAKE_LINKER} ${LD_RAW_FLAGS} -r -sectcreate __DATA __blocks_dat ../blocks/checkpoints.dat -o ${CMAKE_CURRENT_BINARY_DIR}/blocksdat.o stub.o && rm -f stub.*)
   else()
-    add_custom_command(OUTPUT blocksdat.o MAIN_DEPENDENCY ../blocks/checkpoints.dat COMMAND cd ${CMAKE_CURRENT_SOURCE_DIR} && cp ../blocks/checkpoints.dat blocks.dat && ${CMAKE_LINKER} -r -b binary -o ${CMAKE_CURRENT_BINARY_DIR}/blocksdat.o blocks.dat && rm -f blocks.dat)
+    add_custom_command(OUTPUT blocksdat.o MAIN_DEPENDENCY ../blocks/checkpoints.dat COMMAND cd ${CMAKE_CURRENT_SOURCE_DIR} && cp ../blocks/checkpoints.dat blocks.dat && ${CMAKE_LINKER} ${LD_RAW_FLAGS} -r -b binary -o ${CMAKE_CURRENT_BINARY_DIR}/blocksdat.o blocks.dat && rm -f blocks.dat)
   endif()
   set(blocksdat "blocksdat.o")
 endif()

src/blocks/CMakeLists.txt

@@ -30,8 +30,8 @@ if(APPLE)
     add_library(blocks STATIC blockexports.c)
     set_target_properties(blocks PROPERTIES LINKER_LANGUAGE C)
 else()
-    add_custom_command(OUTPUT blocks.o MAIN_DEPENDENCY blocks.dat COMMAND cd ${CMAKE_CURRENT_SOURCE_DIR} && ${CMAKE_LINKER} -r -b binary -o ${CMAKE_CURRENT_BINARY_DIR}/blocks.o blocks.dat)
+    add_custom_command(OUTPUT blocks.o MAIN_DEPENDENCY blocks.dat COMMAND cd ${CMAKE_CURRENT_SOURCE_DIR} && ${CMAKE_LINKER} ${LD_RAW_FLAGS} -r -b binary -o ${CMAKE_CURRENT_BINARY_DIR}/blocks.o blocks.dat)
-    add_custom_command(OUTPUT testnet_blocks.o MAIN_DEPENDENCY testnet_blocks.dat COMMAND cd ${CMAKE_CURRENT_SOURCE_DIR} && ${CMAKE_LINKER} -r -b binary -o ${CMAKE_CURRENT_BINARY_DIR}/testnet_blocks.o testnet_blocks.dat)
+    add_custom_command(OUTPUT testnet_blocks.o MAIN_DEPENDENCY testnet_blocks.dat COMMAND cd ${CMAKE_CURRENT_SOURCE_DIR} && ${CMAKE_LINKER} ${LD_RAW_FLAGS} -r -b binary -o ${CMAKE_CURRENT_BINARY_DIR}/testnet_blocks.o testnet_blocks.dat)
     add_library(blocks STATIC blocks.o testnet_blocks.o blockexports.c)
     set_target_properties(blocks PROPERTIES LINKER_LANGUAGE C)
 endif()

src/daemon/CMakeLists.txt

@@ -29,9 +29,9 @@
 set(blocksdat "")
 if(PER_BLOCK_CHECKPOINT)
   if(APPLE)
-    add_custom_command(OUTPUT blocksdat.o MAIN_DEPENDENCY ../blocks/checkpoints.dat COMMAND cd ${CMAKE_CURRENT_SOURCE_DIR} && touch stub.c && ${CMAKE_C_COMPILER} -o stub.o -c stub.c COMMAND cd ${CMAKE_CURRENT_SOURCE_DIR} && ${CMAKE_LINKER} -r -sectcreate __DATA __blocks_dat ../blocks/checkpoints.dat -o ${CMAKE_CURRENT_BINARY_DIR}/blocksdat.o stub.o && rm -f stub.*)
+    add_custom_command(OUTPUT blocksdat.o MAIN_DEPENDENCY ../blocks/checkpoints.dat COMMAND cd ${CMAKE_CURRENT_SOURCE_DIR} && touch stub.c && ${CMAKE_C_COMPILER} -o stub.o -c stub.c COMMAND cd ${CMAKE_CURRENT_SOURCE_DIR} && ${CMAKE_LINKER} ${LD_RAW_FLAGS} -r -sectcreate __DATA __blocks_dat ../blocks/checkpoints.dat -o ${CMAKE_CURRENT_BINARY_DIR}/blocksdat.o stub.o && rm -f stub.*)
   else()
-    add_custom_command(OUTPUT blocksdat.o MAIN_DEPENDENCY ../blocks/checkpoints.dat COMMAND cd ${CMAKE_CURRENT_SOURCE_DIR} && cp ../blocks/checkpoints.dat blocks.dat && ${CMAKE_LINKER} -r -b binary -o ${CMAKE_CURRENT_BINARY_DIR}/blocksdat.o blocks.dat && rm -f blocks.dat)
+    add_custom_command(OUTPUT blocksdat.o MAIN_DEPENDENCY ../blocks/checkpoints.dat COMMAND cd ${CMAKE_CURRENT_SOURCE_DIR} && cp ../blocks/checkpoints.dat blocks.dat && ${CMAKE_LINKER} ${LD_RAW_FLAGS} -r -b binary -o ${CMAKE_CURRENT_BINARY_DIR}/blocksdat.o blocks.dat && rm -f blocks.dat)
   endif()
   set(blocksdat "blocksdat.o")
 endif()

tests/gtest/cmake/internal_utils.cmake

@@ -87,7 +87,7 @@ macro(config_compiler_and_linker)
     set(cxx_no_exception_flags "-D_HAS_EXCEPTIONS=0")
     set(cxx_no_rtti_flags "-GR-")
   elseif (CMAKE_COMPILER_IS_GNUCXX)
-    set(cxx_base_flags "-Wall -Wshadow")
+    set(cxx_base_flags "-Wall -Wshadow -fPIC")
     set(cxx_exception_flags "-fexceptions")
     set(cxx_no_exception_flags "-fno-exceptions")
     # Until version 4.3.2, GCC doesn't define a macro to indicate