update(build): use elftoolchain/libelf instead of elfutils/libelf

Signed-off-by: Luca Guerra <[email protected]>
falcosecurity · Nov 28, 2024 · 6b3ab43 · 6b3ab43
1 parent efc198f
commit 6b3ab43
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Showing 6 changed files with 22 additions and 31 deletions.
diff --git a/CMakeLists.txt b/CMakeLists.txt
@@ -121,6 +121,8 @@ if(BUILD_SHARED_LIBS)
 	message(STATUS "Shared library soversion: ${FALCOSECURITY_SHARED_LIBS_SOVERSION}")
 endif()
 
+add_subdirectory(contrib/elftoolchain)
+
 include(libscap)
 include(libsinsp)
 

diff --git a/cmake/modules/libbpf.cmake b/cmake/modules/libbpf.cmake
@@ -13,42 +13,45 @@
 # the License.
 #
 
-option(USE_BUNDLED_LIBBPF "Enable building of the bundled libbpf" ${USE_BUNDLED_DEPS})
-
 if(LIBBPF_INCLUDE)
 	# we already have libbpf
-elseif(NOT USE_BUNDLED_LIBBPF)
-	find_path(LIBBPF_INCLUDE bpf/libbpf.h)
-	find_library(LIBBPF_LIB NAMES bpf)
-	if(LIBBPF_INCLUDE AND LIBBPF_LIB)
-		message(STATUS "Found libbpf: include: ${LIBBPF_INCLUDE}, lib: ${LIBBPF_LIB}")
-	else()
-		message(FATAL_ERROR "Couldn't find system libbpf")
-	endif()
 else()
 	include(zlib)
-	include(libelf)
 	set(LIBBPF_SRC "${PROJECT_BINARY_DIR}/libbpf-prefix/src")
 	set(LIBBPF_BUILD_DIR "${LIBBPF_SRC}/libbpf-build")
 	set(LIBBPF_INCLUDE "${LIBBPF_BUILD_DIR}/root/usr/include")
 	set(LIBBPF_LIB "${LIBBPF_BUILD_DIR}/root/usr/lib64/libbpf.a")
+
+	get_target_property(LIBELF_INCLUDE_DIR elf INCLUDE_DIRECTORIES)
+
+	foreach(dir ${LIBELF_INCLUDE_DIR})
+		string(APPEND LIBELF_COMPILER_STRING "-I${dir} ")
+	endforeach()
+
 	ExternalProject_Add(
 		libbpf
 		PREFIX "${PROJECT_BINARY_DIR}/libbpf-prefix"
-		DEPENDS zlib libelf
+		DEPENDS zlib elf
 		URL "https://github.com/libbpf/libbpf/archive/refs/tags/v1.3.0.tar.gz"
 		URL_HASH "SHA256=11db86acd627e468bc48b7258c1130aba41a12c4d364f78e184fd2f5a913d861"
 		CONFIGURE_COMMAND mkdir -p build root
 		BUILD_COMMAND
 			make BUILD_STATIC_ONLY=y OBJDIR=${LIBBPF_BUILD_DIR}/build
 			DESTDIR=${LIBBPF_BUILD_DIR}/root NO_PKG_CONFIG=1
-			"EXTRA_CFLAGS=-fPIC -I${LIBELF_INCLUDE} -I${ZLIB_INCLUDE}" "LDFLAGS=-Wl,-Bstatic"
+			"EXTRA_CFLAGS=-fPIC ${LIBELF_COMPILER_STRING} -I${ZLIB_INCLUDE}" "LDFLAGS=-Wl,-Bstatic"
 			"EXTRA_LDFLAGS=-L${LIBELF_SRC}/libelf/libelf -L${ZLIB_SRC}" -C ${LIBBPF_SRC}/libbpf/src
 			install install_uapi_headers
 		INSTALL_COMMAND ""
 		UPDATE_COMMAND ""
 		BUILD_BYPRODUCTS ${LIBBPF_LIB}
 	)
+
+	add_library(bpf STATIC IMPORTED)
+	set_target_properties(bpf PROPERTIES IMPORTED_LOCATION ${LIBBPF_LIB})
+	file(MAKE_DIRECTORY ${LIBBPF_INCLUDE}) # necessary to make target_include_directories() work
+	target_include_directories(bpf INTERFACE ${LIBBPF_INCLUDE})
+	target_link_libraries(bpf INTERFACE elf ${ZLIB_LIB})
+
 	message(STATUS "Using bundled libbpf: include'${LIBBPF_INCLUDE}', lib: ${LIBBPF_LIB}")
 	install(
 		FILES "${LIBBPF_LIB}"
@@ -57,8 +60,3 @@ else()
 	)
 endif()
 
-if(NOT TARGET libbpf)
-	add_custom_target(libbpf)
-endif()
-
-include_directories(${LIBBPF_INCLUDE})
diff --git a/userspace/libpman/CMakeLists.txt b/userspace/libpman/CMakeLists.txt
@@ -35,23 +35,17 @@ target_include_directories(
 			$<BUILD_INTERFACE:${LIBS_DIR}> # ppm_enum and tables
 			$<BUILD_INTERFACE:${LIBS_DIR}/userspace> # scap-stats struct
 			${ZLIB_INCLUDE}
-			${LIBBPF_INCLUDE}
 			${MODERN_BPF_SKEL_DIR}
-			${LIBELF_INCLUDE}
 )
 
 target_link_libraries(
-	pman PUBLIC scap_event_schema scap_platform ${LIBBPF_LIB} ${LIBELF_LIB} ${ZLIB_LIB}
+	pman PUBLIC scap_event_schema scap_platform bpf ${ZLIB_LIB}
 )
 
 if(TARGET ProbeSkeleton)
 	add_dependencies(pman ProbeSkeleton)
 endif()
 
-if(USE_BUNDLED_LIBBPF)
-	add_dependencies(pman libbpf)
-endif()
-
 install(
 	TARGETS pman
 	ARCHIVE DESTINATION "${CMAKE_INSTALL_LIBDIR}"

diff --git a/userspace/libscap/CMakeLists.txt b/userspace/libscap/CMakeLists.txt
@@ -170,14 +170,12 @@ if(HAS_ENGINE_KMOD)
 endif()
 
 if(HAS_ENGINE_BPF)
-	include(libelf)
 	add_subdirectory(engine/bpf)
 	target_link_libraries(scap PUBLIC scap_engine_bpf)
 	target_include_directories(scap_engine_bpf PRIVATE ${PROJECT_BINARY_DIR}/driver/src)
 endif()
 
 if(HAS_ENGINE_MODERN_BPF)
-	include(libelf)
 	add_subdirectory(engine/modern_bpf)
 	target_link_libraries(scap PUBLIC scap_engine_modern_bpf)
 	target_include_directories(scap_engine_modern_bpf PRIVATE ${PROJECT_BINARY_DIR}/driver/src)

diff --git a/userspace/libscap/engine/bpf/CMakeLists.txt b/userspace/libscap/engine/bpf/CMakeLists.txt
@@ -13,11 +13,10 @@
 # the License.
 #
 add_library(scap_engine_bpf scap_bpf.c attached_prog.c)
-add_dependencies(scap_engine_bpf libelf zlib)
+add_dependencies(scap_engine_bpf zlib)
 target_link_libraries(
 	scap_engine_bpf PRIVATE scap_event_schema scap_platform scap_engine_util scap_error
-							${LIBELF_LIB} ${ZLIB_LIB}
+							elf ${ZLIB_LIB}
 )
-target_include_directories(scap_engine_bpf PRIVATE ${LIBELF_INCLUDE})
 
 set_scap_target_properties(scap_engine_bpf)
diff --git a/userspace/libscap/engine/bpf/scap_bpf.c b/userspace/libscap/engine/bpf/scap_bpf.c
@@ -706,7 +706,7 @@ static int32_t load_bpf_file(struct bpf_engine *handle) {
 			                      handle->m_filepath);
 		}
 
-		handle->elf = elf_begin(handle->program_fd, ELF_C_READ_MMAP_PRIVATE, NULL);
+		handle->elf = elf_begin(handle->program_fd, ELF_C_READ, NULL);
 		if(!handle->elf) {
 			scap_errprintf(handle->m_lasterr, 0, "can't read ELF format");
 			goto end;