Linux下SGX的使用（1）-makefile阅读

预备

Ubuntu：Ubuntu 16.04.1 LTS
SGX版本：Intel SGX Linux 1.8 Release 下载地址：https://01.org/zh/intel-software-guard-extensions/downloads?langredirect=1
安装过程：https://download.01.org/intel-sgx/linux-1.8/docs/Intel_SGX_SDK_Installation_Guide_Linux_1.8_Open_Source.pdf
Windows下Hello world https://software.intel.com/zh-cn/SGX-Development-Guide-Part-1?language=de

Linux下SGX的使用解读

为了使用SGX，我们先读一下SGX的例子，因为总体思路就是阅读makefile文件，查看编译过程，再看编译的代码，首先我们在Sgxsdk中的例子中的“SampleEnclave”的makefile文件

######## SGX SDK Settings ########

SGX_SDK ?= /opt/intel/sgxsdk   //查看SGX_SDK是否被定义，如果定义的话，就不进行赋值，否则进行赋值
SGX_MODE ?= HW               //默认是HW
SGX_ARCH ?= x64              //默认是64位
SGX_DEBUG ?= 1               //默认是1

ifeq ($(shell getconf LONG_BIT), 32)     #判断机器的位数
    SGX_ARCH := x86                      #32位
else ifeq ($(findstring -m32, $(CXXFLAGS)), -m32)   
#在C++编译器中，对数入的指令查找-m32指令，找到这个指令就代表要生乘32位的代码
#GCC命令行参数，看看各个版本的区别——
#32位版：加上 -m32 参数，生成32位的代码。
#64位版：加上 -m64 参数，生成64位的代码。
    SGX_ARCH := x86
endif

ifeq ($(SGX_ARCH), x86)
    SGX_COMMON_CFLAGS := -m32
    SGX_LIBRARY_PATH := $(SGX_SDK)/lib
    SGX_ENCLAVE_SIGNER := $(SGX_SDK)/bin/x86/sgx_sign
    SGX_EDGER8R := $(SGX_SDK)/bin/x86/sgx_edger8r
else
    SGX_COMMON_CFLAGS := -m64                    #设定64位指令，生成64位程序
    SGX_LIBRARY_PATH := $(SGX_SDK)/lib64         #设定函数编译过程中使用的函数库
    SGX_ENCLAVE_SIGNER := $(SGX_SDK)/bin/x64/sgx_sign   #设定签名的程序的位置
    SGX_EDGER8R := $(SGX_SDK)/bin/x64/sgx_edger8r   #设定对edl文件处理的程序
endif

ifeq ($(SGX_DEBUG), 1)
ifeq ($(SGX_PRERELEASE), 1)
$(error Cannot set SGX_DEBUG and SGX_PRERELEASE at the same time!!)
endif
endif

ifeq ($(SGX_DEBUG), 1)
        SGX_COMMON_CFLAGS += -O0 -g             #添加-O0  (不优化，大写字母O,和数字0) ，-g    (产生调试信息，相当于debug开关)
else
        SGX_COMMON_CFLAGS += -O2                 #-O2是在速度与程序体积上取得平衡的优化
endif

######## App Settings ########                   #APP的设置

ifneq ($(SGX_MODE), HW)
    Urts_Library_Name := sgx_urts_sim
else
    Urts_Library_Name := sgx_urts
endif

App_Cpp_Files := App/App.cpp $(wildcard App/Edger8rSyntax/*.cpp) $(wildcard App/TrustedLibrary/*.cpp)

#App_Cpp_Files代表App.cpp，以及App/Edger8rSyntax中的cpp文件，App/TrustedLibrary中的所有cpp文件

App_Include_Paths := -IInclude -IApp -I$(SGX_SDK)/include
#APP_Include_Paths的内容是-IInclude -IApp -I/opt/intel/sgxsdk/include

App_C_Flags := $(SGX_COMMON_CFLAGS) -fPIC -Wno-attributes $(App_Include_Paths)
#APP_C_Flags的内容是-IInclude -IApp -I/opt/intel/sgxsdk/include其中-I表示指定要链接的库

# Three configuration modes - Debug, prerelease, release
#   Debug - Macro DEBUG enabled.
#   Prerelease - Macro NDEBUG and EDEBUG enabled. 宏观NDEBUG和EDEBUG
#   Release - Macro NDEBUG enabled.
ifeq ($(SGX_DEBUG), 1)
        App_C_Flags += -DDEBUG -UNDEBUG -UEDEBUG
else ifeq ($(SGX_PRERELEASE), 1)
        App_C_Flags += -DNDEBUG -DEDEBUG -UDEBUG
else
        App_C_Flags += -DNDEBUG -UEDEBUG -UDEBUG
endif

App_Cpp_Flags := $(App_C_Flags) -std=c++11  增加新的编译条件
App_Link_Flags := $(SGX_COMMON_CFLAGS) -L$(SGX_LIBRARY_PATH) -l$(Urts_Library_Name) -lpthread 
ifneq ($(SGX_MODE), HW) #HW模式下要做的改变
    App_Link_Flags += -lsgx_uae_service_sim
else
    App_Link_Flags += -lsgx_uae_service
endif

App_Cpp_Objects := $(App_Cpp_Files:.cpp=.o) #将对应的Cpp文件换成后缀是o的文件

App_Name := app

######## Enclave Settings ########

ifneq ($(SGX_MODE), HW)
    Trts_Library_Name := sgx_trts_sim
    Service_Library_Name := sgx_tservice_sim
else
    Trts_Library_Name := sgx_trts
    Service_Library_Name := sgx_tservice
endif
Crypto_Library_Name := sgx_tcrypto

Enclave_Cpp_Files := Enclave/Enclave.cpp $(wildcard Enclave/Edger8rSyntax/*.cpp) $(wildcard Enclave/TrustedLibrary/*.cpp)
Enclave_Include_Paths := -IInclude -IEnclave -I$(SGX_SDK)/include -I$(SGX_SDK)/include/tlibc -I$(SGX_SDK)/include/stlport

Enclave_C_Flags := $(SGX_COMMON_CFLAGS) -nostdinc -fvisibility=hidden -fpie -fstack-protector $(Enclave_Include_Paths)
Enclave_Cpp_Flags := $(Enclave_C_Flags) -std=c++03 -nostdinc++

# To generate a proper enclave, it is recommended to follow below guideline to link the trusted libraries:
#    1. Link sgx_trts with the `--whole-archive' and `--no-whole-archive' options,
#       so that the whole content of trts is included in the enclave.
#    2. For other libraries, you just need to pull the required symbols.
#       Use `--start-group' and `--end-group' to link these libraries.
# Do NOT move the libraries linked with `--start-group' and `--end-group' within `--whole-archive' and `--no-whole-archive' options.
# Otherwise, you may get some undesirable errors.
Enclave_Link_Flags := $(SGX_COMMON_CFLAGS) -Wl,--no-undefined -nostdlib -nodefaultlibs -nostartfiles -L$(SGX_LIBRARY_PATH) \
    -Wl,--whole-archive -l$(Trts_Library_Name) -Wl,--no-whole-archive \
    -Wl,--start-group -lsgx_tstdc -lsgx_tstdcxx -l$(Crypto_Library_Name) -l$(Service_Library_Name) -Wl,--end-group \
    -Wl,-Bstatic -Wl,-Bsymbolic -Wl,--no-undefined \
    -Wl,-pie,-eenclave_entry -Wl,--export-dynamic  \
    -Wl,--defsym,__ImageBase=0 \
    -Wl,--version-script=Enclave/Enclave.lds

Enclave_Cpp_Objects := $(Enclave_Cpp_Files:.cpp=.o)

Enclave_Name := enclave.so
Signed_Enclave_Name := enclave.signed.so
Enclave_Config_File := Enclave/Enclave.config.xml

ifeq ($(SGX_MODE), HW)
ifeq ($(SGX_DEBUG), 1)
    Build_Mode = HW_DEBUG
else ifeq ($(SGX_PRERELEASE), 1)
    Build_Mode = HW_PRERELEASE
else
    Build_Mode = HW_RELEASE
endif
else
ifeq ($(SGX_DEBUG), 1)
    Build_Mode = SIM_DEBUG
else ifeq ($(SGX_PRERELEASE), 1)
    Build_Mode = SIM_PRERELEASE
else
    Build_Mode = SIM_RELEASE
endif
endif


.PHONY: all run

ifeq ($(Build_Mode), HW_RELEASE)
all: .config_$(Build_Mode)_$(SGX_ARCH) $(App_Name) $(Enclave_Name)
    @echo "The project has been built in release hardware mode."
    @echo "Please sign the $(Enclave_Name) first with your signing key before you run the $(App_Name) to launch and access the enclave."
    @echo "To sign the enclave use the command:"
    @echo "   $(SGX_ENCLAVE_SIGNER) sign -key  -enclave $(Enclave_Name) -out <$(Signed_Enclave_Name)> -config $(Enclave_Config_File)"
    @echo "You can also sign the enclave using an external signing tool."
    @echo "To build the project in simulation mode set SGX_MODE=SIM. To build the project in prerelease mode set SGX_PRERELEASE=1 and SGX_MODE=HW."
else
all: .config_$(Build_Mode)_$(SGX_ARCH) $(App_Name) $(Signed_Enclave_Name)
ifeq ($(Build_Mode), HW_DEBUG)
    @echo "The project has been built in debug hardware mode."
else ifeq ($(Build_Mode), SIM_DEBUG)
    @echo "The project has been built in debug simulation mode."
else ifeq ($(Build_Mode), HW_PRERELEASE)
    @echo "The project has been built in pre-release hardware mode."
else ifeq ($(Build_Mode), SIM_PRERELEASE)
    @echo "The project has been built in pre-release simulation mode."
else
    @echo "The project has been built in release simulation mode."
endif
endif

run: all
ifneq ($(Build_Mode), HW_RELEASE)
    @$(CURDIR)/$(App_Name)
    @echo "RUN  =>  $(App_Name) [$(SGX_MODE)|$(SGX_ARCH), OK]"
endif

######## App Objects ########整个文件的核心

App/Enclave_u.c: $(SGX_EDGER8R) Enclave/Enclave.edl #使用$(SGX_SDK)/bin/x86/sgx_edger8r中的工具对Enclave中的enclave进行处理
    @cd App && $(SGX_EDGER8R) --untrusted ../Enclave/Enclave.edl --search-path ../Enclave --search-path $(SGX_SDK)/include
    #上述指令的操作是，首先进入到APP文件夹，之后使用sgx_edger8r中相应的指令，产生Enclave_u.h和Enclave_u.c,其中sgx_edger8r的使用方式是
    #sgx_edger8r [options] <.edl file> [another .edl file ...]
    #参考SDK文档中对sgx_edger8r的说明
    @echo "GEN  =>  $@"

App/Enclave_u.o: App/Enclave_u.c     #产生Enclave_u.o文件
    @$(CC) $(App_C_Flags) -c $< -o $@
    @echo "CC   <=  $<"

App/%.o: App/%.cpp                     #将APP文件夹中的cpp都编译成后缀是.o的文件
    @$(CXX) $(App_Cpp_Flags) -c $< -o $@
    @echo "CXX  <=  $<"

$(App_Name): App/Enclave_u.o $(App_Cpp_Objects)#将Enclave中的后缀位o的文件以及enclave的不可信部分编译出app可执行文件
    @$(CXX) $^ -o $@ $(App_Link_Flags)
    @echo "LINK =>  $@"

.config_$(Build_Mode)_$(SGX_ARCH):
    @rm -f .config_* $(App_Name) $(Enclave_Name) $(Signed_Enclave_Name) $(App_Cpp_Objects) App/Enclave_u.* $(Enclave_Cpp_Objects) Enclave/Enclave_t.*
    @touch .config_$(Build_Mode)_$(SGX_ARCH)

######## Enclave Objects ########

Enclave/Enclave_t.c: $(SGX_EDGER8R) Enclave/Enclave.edl #生成可信文件Enclave_t.c和enclave_t.h
    @cd Enclave && $(SGX_EDGER8R) --trusted ../Enclave/Enclave.edl --search-path ../Enclave --search-path $(SGX_SDK)/include
    @echo "GEN  =>  $@"

Enclave/Enclave_t.o: Enclave/Enclave_t.c  #生成可信文件Enclave_t.o
    @$(CC) $(Enclave_C_Flags) -c $< -o $@
    @echo "CC   <=  $<"

Enclave/%.o: Enclave/%.cpp              #编译CPP到文件变成o文件
    @$(CXX) $(Enclave_Cpp_Flags) -c $< -o $@
    @echo "CXX  <=  $<"

$(Enclave_Name): Enclave/Enclave_t.o $(Enclave_Cpp_Objects)   #生成enclave.so
    @$(CXX) $^ -o $@ $(Enclave_Link_Flags)
    @echo "LINK =>  $@"

$(Signed_Enclave_Name): $(Enclave_Name)             #对文件进行签名
    @$(SGX_ENCLAVE_SIGNER) sign -key Enclave/Enclave_private.pem -enclave $(Enclave_Name) -out $@ -config $(Enclave_Config_File)   #参考sgx_sign的使用方法
    @echo "SIGN =>  $@"

.PHONY: clean

clean:
    @rm -f .config_* $(App_Name) $(Enclave_Name) $(Signed_Enclave_Name) $(App_Cpp_Objects) App/Enclave_u.* $(Enclave_Cpp_Objects) Enclave/Enclave_t.*

因此，如果我们要使用SGX，只需要修改makefile规则中的需要编译的文件名称即可