openwrt/package/network/utils/bpftool/patches/003-skip-crypto.patch

From 9ba0b4add39e578ccdb91ca23b62a7de6ff45995 Mon Sep 17 00:00:00 2001
From: Mykyta Yatsenko <yatsenko@meta.com>
Date: Thu, 12 Mar 2026 17:03:27 -0700
Subject: [PATCH] bpftool: Allow explicitly skip llvm, libbfd and libcrypto
 dependencies

Introduce SKIP_LLVM, SKIP_LIBBFD, and SKIP_CRYPTO build flags that let
users build bpftool without these optional dependencies.

SKIP_LLVM=1 skips LLVM even when detected. SKIP_LIBBFD=1 prevents the
libbfd JIT disassembly fallback when LLVM is absent. Together, they
produce a bpftool with no disassembly support.

SKIP_CRYPTO=1 excludes sign.c and removes the -lcrypto link dependency.
Inline stubs in main.h return errors with a clear message if signing
functions are called at runtime.

Use BPFTOOL_WITHOUT_CRYPTO (not HAVE_LIBCRYPTO_SUPPORT) as the C
define, following the BPFTOOL_WITHOUT_SKELETONS naming convention for
bpftool-internal build config, leaving HAVE_LIBCRYPTO_SUPPORT free for
proper feature detection in the future.

All three flags are propagated through the selftests Makefile to bpftool
sub-builds.

Signed-off-by: Mykyta Yatsenko <yatsenko@meta.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20260312-b4-bpftool_build-v2-1-4c9d57133644@meta.com
---
 src/Makefile | 30 ++++++++++++++++++++++++++----
 src/main.c   |  7 +++++++
 src/main.h   | 14 ++++++++++++++
 3 files changed, 47 insertions(+), 4 deletions(-)

--- a/src/Makefile
+++ b/src/Makefile
@@ -95,6 +95,15 @@ RM ?= rm -f
 
 FEATURE_USER = .bpftool
 
+# Skip optional dependencies: LLVM (JIT disasm), libbfd (fallback
+# disasm), libcrypto (program signing).
+SKIP_LLVM ?=
+SKIP_LIBBFD ?=
+SKIP_CRYPTO ?=
+ifneq ($(SKIP_CRYPTO),1)
+  CRYPTO_LIBS := -lcrypto
+endif
+
 FEATURE_TESTS := clang-bpf-co-re
 FEATURE_TESTS += llvm
 FEATURE_TESTS += libcap
@@ -124,8 +133,8 @@ ifeq ($(check_feat),1)
 include Makefile.feature
 endif
 
-LIBS = $(LIBBPF) -lelf -lcrypto -lz
-LIBS_BOOTSTRAP = $(LIBBPF_BOOTSTRAP) -lelf -lcrypto -lz
+LIBS = $(LIBBPF) -lelf $(CRYPTO_LIBS) -lz
+LIBS_BOOTSTRAP = $(LIBBPF_BOOTSTRAP) -lelf $(CRYPTO_LIBS) -lz
 
 ifeq ($(feature-libelf-zstd),1)
 LIBS += -lzstd
@@ -144,7 +153,12 @@ all: $(OUTPUT)bpftool
 SRCS := $(wildcard *.c)
 
 ifeq ($(feature-llvm),1)
-  # If LLVM is available, use it for JIT disassembly
+ifneq ($(SKIP_LLVM),1)
+HAS_LLVM := 1
+endif
+endif
+
+ifeq ($(HAS_LLVM),1)
   CFLAGS  += -DHAVE_LLVM_SUPPORT
   LLVM_CONFIG_LIB_COMPONENTS := mcdisassembler all-targets
   # llvm-config always adds -D_GNU_SOURCE, however, it may already be in CFLAGS
@@ -159,6 +173,7 @@ ifeq ($(feature-llvm),1)
   endif
   LDFLAGS += $(shell $(LLVM_CONFIG) --ldflags)
 else
+  ifneq ($(SKIP_LIBBFD),1)
   # Fall back on libbfd
   ifeq ($(feature-libbfd),1)
     LIBS += -lbfd -ldl -lopcodes
@@ -180,15 +195,22 @@ else
       CFLAGS += -DDISASM_INIT_STYLED
     endif
   endif
+  endif # SKIP_LIBBFD
 endif
 ifeq ($(filter -DHAVE_LLVM_SUPPORT -DHAVE_LIBBFD_SUPPORT,$(CFLAGS)),)
   # No support for JIT disassembly
   SRCS := $(filter-out jit_disasm.c,$(SRCS))
 endif
 
+ifeq ($(SKIP_CRYPTO),1)
+  CFLAGS += -DBPFTOOL_WITHOUT_CRYPTO
+  HOST_CFLAGS += -DBPFTOOL_WITHOUT_CRYPTO
+  SRCS := $(filter-out sign.c,$(SRCS))
+endif
+
 BPFTOOL_BOOTSTRAP := $(BOOTSTRAP_OUTPUT)bpftool
 
-BOOTSTRAP_OBJS = $(addprefix $(BOOTSTRAP_OUTPUT),main.o common.o json_writer.o gen.o btf.o sign.o)
+BOOTSTRAP_OBJS = $(addprefix $(BOOTSTRAP_OUTPUT),main.o common.o json_writer.o gen.o btf.o $(if $(CRYPTO_LIBS),sign.o))
 $(BOOTSTRAP_OBJS): $(LIBBPF_BOOTSTRAP)
 
 OBJS = $(patsubst %.c,$(OUTPUT)%.o,$(SRCS)) $(OUTPUT)disasm.o
--- a/src/main.c
+++ b/src/main.c
@@ -132,6 +132,11 @@ static int do_version(int argc, char **a
 #else
 	const bool has_skeletons = true;
 #endif
+#ifdef BPFTOOL_WITHOUT_CRYPTO
+	const bool has_crypto = false;
+#else
+	const bool has_crypto = true;
+#endif
 	bool bootstrap = false;
 	int i;
 
@@ -163,6 +168,7 @@ static int do_version(int argc, char **a
 		jsonw_start_object(json_wtr);	/* features */
 		jsonw_bool_field(json_wtr, "libbfd", has_libbfd);
 		jsonw_bool_field(json_wtr, "llvm", has_llvm);
+		jsonw_bool_field(json_wtr, "crypto", has_crypto);
 		jsonw_bool_field(json_wtr, "skeletons", has_skeletons);
 		jsonw_bool_field(json_wtr, "bootstrap", bootstrap);
 		jsonw_end_object(json_wtr);	/* features */
@@ -181,6 +187,7 @@ static int do_version(int argc, char **a
 		printf("features:");
 		print_feature("libbfd", has_libbfd, &nb_features);
 		print_feature("llvm", has_llvm, &nb_features);
+		print_feature("crypto", has_crypto, &nb_features);
 		print_feature("skeletons", has_skeletons, &nb_features);
 		print_feature("bootstrap", bootstrap, &nb_features);
 		printf("\n");
--- a/src/main.h
+++ b/src/main.h
@@ -293,6 +293,20 @@ struct kernel_config_option {
 int read_kernel_config(const struct kernel_config_option *requested_options,
 		       size_t num_options, char **out_values,
 		       const char *define_prefix);
+#ifndef BPFTOOL_WITHOUT_CRYPTO
 int bpftool_prog_sign(struct bpf_load_and_run_opts *opts);
 __u32 register_session_key(const char *key_der_path);
+#else
+static inline int bpftool_prog_sign(struct bpf_load_and_run_opts *opts)
+{
+	p_err("bpftool was built without signing support");
+	return -ENOTSUP;
+}
+
+static inline __u32 register_session_key(const char *key_der_path)
+{
+	p_err("bpftool was built without signing support");
+	return -1;
+}
+#endif
 #endif