tools/syz-declextract: parse Linux Headers to extract metadata about …

…syscalls

Clang tool that uses AST matchers to extract relevant metadata about Linux system calls. The tool is to be extended
later to support more interfaces, collect more relevant metadata and to automatically generate syzkaller descriptions

Makefile

@@ -259,7 +259,7 @@ format_go:
 format_cpp:
 	clang-format --style=file -i executor/*.cc executor/*.h \
 		executor/android/android_seccomp.h \
-		tools/kcovtrace/*.c tools/kcovfuzzer/*.c tools/fops_probe/*.cc
+		tools/kcovtrace/*.c tools/kcovfuzzer/*.c tools/fops_probe/*.cc tools/syz-declextract/syz-declextract.cpp
 
 format_sys: bin/syz-fmt
 	bin/syz-fmt all

tools/syz-declextract/.clang-format

@@ -0,0 +1,2 @@
+BasedOnStyle: LLVM
+ColumnLimit: 120

tools/syz-declextract/README.md

@@ -0,0 +1,37 @@
+# syz-declextract
+## Linux Kernel (For testing purposes)
+```
+export KERNEL=$PWD/linux-stable
+git clone git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git $KERNEL
+cd $KERNEL
+make CC=clang defconfig # Having clang as the compiler is optional but removes erros later on
+./scripts/config -e FTRACE_SYSCALLS
+make CC=clang olddefconfig
+make CC=clang -j`nproc` # kernel has to be built at least once for the script to work
+./scripts/clang/gen_compile_commands.py
+```
+## LLVM Project
+```
+LLVM=$PWD/llvm-project
+git clone https://github.com/llvm/llvm-project.git $LLVM
+cd $LLVM
+git checkout 0f231567719c99caa99164d8f91bad50883dab03 # In case of any breaking changes, this commit works
+echo 'add_clang_executable(syz-declextract syz-declextract/syz-declextract.cpp)
+target_link_libraries(syz-declextract PRIVATE clangTooling)' >> $LLVM/clang/CMakeLists.txt
+```
+## syz-declextract
+```
+mkdir $LLVM/clang/syz-declextract
+```
+Download `syz-declextract.cpp` file and add it to `$LLVM/clang/syz-declextract` directory
+```
+SYZ=$PWD/syz
+mkdir $SYZ && cd $SYZ
+cmake -DLLVM_ENABLE_PROJECTS="clang" -DCMAKE_BUILD_TYPE=Release -DCMAKE_EXPORT_COMPILE_COMMANDS=ON \
+-DCMAKE_C_COMPILER=clang -DCMAKE_CXX_COMPILER=clang++ $LLVM/llvm
+make -j`nproc` syz-declextract
+```
+## Example
+```
+./bin/syz-declextract $KERNEL/fs/read_write.c | less # or any other .c file
+```