[PATCH v2 12/19] Allow selective crypto module loading at boot based on FIPS mode

Jay Wang
2026-04-18T00:23:50Z

Introduce CONFIG_CRYPTO_FIPS140_DUAL_VERSION to enable dual crypto module
versions within a single kernel build, allowing boot-time selection based on
FIPS mode status.

This configuration allows FIPS mode to use pre-compiled certified crypto
modules from external source, while regular mode uses freshly built kernel
crypto implementation for optimal performance and latest security features.

The implementation embeds both certified and non-certified fips140.ko
modules in vmlinux and adds new linker sections (.nonfips140_embedded,
.nonfips140_btf) for non-FIPS crypto module storage. It modifies
fips140-loader.c to select appropriate module at boot time based on
fips_enabled flag, updates build system to generate and embed both module
versions, and includes BTF support for both module variants when
CONFIG_DEBUG_INFO_BTF_MODULES is enabled.

For modular crypto algorithms (e.g., aes.ko), they are not automatically
duplicated. They should either be built-in to fips140.ko for automatic
duplication, or require userspace utilities like modprobe to handle
proper isolation between FIPS and non-FIPS modular crypto implementations.

Signed-off-by: Jay Wang <wanjay@amazon.com>
---
Makefile | 15 +++++++++++++++
arch/arm64/kernel/vmlinux.lds.S | 16 ++++++++++++++++
arch/x86/kernel/vmlinux.lds.S | 16 ++++++++++++++++
crypto/fips140/Kconfig | 24 ++++++++++++++++++++++++
crypto/fips140/Makefile | 5 ++++-
crypto/fips140/fips140-loader.c | 26 ++++++++++++++++++++++++++
scripts/Makefile.vmlinux | 29 +++++++++++++++++++++++++++--
scripts/link-vmlinux.sh | 6 ++++++
8 files changed, 134 insertions(+), 3 deletions(-)

diff --git a/Makefile b/Makefile
index bd0e4034927c6..4cf7349d5d263 100644
--- a/Makefile
+++ b/Makefile
@@ -1318,9 +1318,11 @@ quiet_cmd_gen_fips140_exported =
awk '{print "0x00000000\t" $$1 "\tcrypto/fips140/fips140\tEXPORT_SYMBOL_GPL\t"}' > $@ \
$(fips140_cp_exported)

+ifndef CONFIG_CRYPTO_FIPS140_DUAL_VERSION
ifeq ($(CONFIG_CRYPTO_FIPS140_EXTMOD_SOURCE),y)
fips140_cp_exported = ; cp "$(fips140_build)/crypto/fips140/.fips140.exported" crypto/fips140/.fips140.exported
endif
+endif

crypto/fips140/.fips140.exported: crypto/fips140/fips140.o FORCE
$(call if_changed,gen_fips140_exported)
@@ -1367,11 +1369,22 @@ vmlinux: private _LDFLAGS_vmlinux := $(LDFLAGS_vmlinux)
vmlinux: export LDFLAGS_vmlinux = $(_LDFLAGS_vmlinux)
ifdef CONFIG_CRYPTO_FIPS140_EXTMOD
vmlinux: crypto/fips140/fips140-embedded.o crypto/fips140/fips140-digest.o
+ifdef CONFIG_CRYPTO_FIPS140_DUAL_VERSION
+vmlinux: crypto/fips140/nonfips140-embedded.o
+endif
crypto/fips140/fips140-embedded.o: fips140-ready
@echo " LD $@"
@$(LD) -r -b binary -o $@ $(fips140_build)/crypto/fips140/fips140.ko
@$(OBJCOPY) --rename-section .data=.fips140_module_data $@

+ifdef CONFIG_CRYPTO_FIPS140_DUAL_VERSION
+crypto/fips140/nonfips140-embedded.o: fips140-ready
+ @echo " LD $@"
+ @$(LD) -r -b binary -o $@ crypto/fips140/fips140.ko
+ @$(OBJCOPY) --rename-section .data=.nonfips140_module_data \
+ --prefix-symbols nonfips140_ $@
+endif
+
crypto/fips140/.fips140.hmac: crypto/fips140/fips140-embedded.o
@echo " HMAC $@"
@hmac_key=$$(awk -F'"' '/^CONFIG_CRYPTO_FIPS140_HMAC_KEY=/{print $$2}' .config); \
@@ -1389,9 +1402,11 @@ fips140-ready: crypto/fips140/fips140.o crypto/fips140/.fips140.order crypto/fip
ifneq ($(KBUILD_MODPOST_NOFINAL),1)
$(Q)$(MAKE) KBUILD_MODULES=y crypto-module-gen=1 -f $(srctree)/scripts/Makefile.modfinal
endif
+ifndef CONFIG_CRYPTO_FIPS140_DUAL_VERSION
ifeq ($(CONFIG_CRYPTO_FIPS140_EXTMOD_SOURCE),y)
cp "$(fips140_build)/crypto/fips140/fips140.ko" crypto/fips140/fips140.ko;
endif
+endif

# Generate fips140.o from crypto-module.a files
crypto/fips140/fips140.o: crypto-module.a FORCE
diff --git a/arch/arm64/kernel/vmlinux.lds.S b/arch/arm64/kernel/vmlinux.lds.S
index 53acbe87b4539..c50072870bcae 100644
--- a/arch/arm64/kernel/vmlinux.lds.S
+++ b/arch/arm64/kernel/vmlinux.lds.S
@@ -223,6 +223,22 @@ SECTIONS
__stop_fips140_btf = .;
}
#endif
+#ifdef CONFIG_CRYPTO_FIPS140_DUAL_VERSION
+ .nonfips140_embedded : {
+ . = ALIGN(8);
+ _binary_nonfips140_ko_start = .;
+ KEEP(*(.nonfips140_module_data))
+ _binary_nonfips140_ko_end = .;
+ }
+#ifdef CONFIG_DEBUG_INFO_BTF_MODULES
+ .nonfips140_btf : {
+ . = ALIGN(8);
+ __start_nonfips140_btf = .;
+ KEEP(*(.nonfips140_btf))
+ __stop_nonfips140_btf = .;
+ }
+#endif
+#endif
#endif

HYPERVISOR_RODATA_SECTIONS
diff --git a/arch/x86/kernel/vmlinux.lds.S b/arch/x86/kernel/vmlinux.lds.S
index d06ac39f931bd..d5d123a398fec 100644
--- a/arch/x86/kernel/vmlinux.lds.S
+++ b/arch/x86/kernel/vmlinux.lds.S
@@ -193,6 +193,22 @@ SECTIONS
__stop_fips140_btf = .;
}
#endif
+#ifdef CONFIG_CRYPTO_FIPS140_DUAL_VERSION
+ .nonfips140_embedded : AT(ADDR(.nonfips140_embedded) - LOAD_OFFSET) {
+ . = ALIGN(8);
+ _binary_nonfips140_ko_start = .;
+ KEEP(*(.nonfips140_module_data))
+ _binary_nonfips140_ko_end = .;
+ }
+#ifdef CONFIG_DEBUG_INFO_BTF_MODULES
+ .nonfips140_btf : AT(ADDR(.nonfips140_btf) - LOAD_OFFSET) {
+ . = ALIGN(8);
+ __start_nonfips140_btf = .;
+ KEEP(*(.nonfips140_btf))
+ __stop_nonfips140_btf = .;
+ }
+#endif
+#endif
#endif

/* Data */
diff --git a/crypto/fips140/Kconfig b/crypto/fips140/Kconfig
index 68b877f0dbab7..7d8997aa10945 100644
--- a/crypto/fips140/Kconfig
+++ b/crypto/fips140/Kconfig
@@ -42,3 +42,27 @@ config CRYPTO_FIPS140_EXTMOD_SOURCE
- fips140_build/crypto/sha256.ko

If unsure, say N.
+config CRYPTO_FIPS140_DUAL_VERSION
+ bool "Enable dual crypto versions for FIPS and regular modes"
+ depends on CRYPTO_FIPS140_EXTMOD && CRYPTO_FIPS140_EXTMOD_SOURCE
+ default n
+ help
+ Enable keeping two crypto module versions in the same kernel build
+ for boot-time switching based on FIPS mode status. This allows:
+ - Non-FIPS users: Get latest crypto algorithms built from current
+ kernel sources for optimal performance and security features
+ - FIPS users: Get pre-compiled certified crypto modules that have
+ undergone formal validation and certification processes
+
+ When enabled:
+
+ For core fips140.ko:
+ - FIPS mode: Uses certified module from CRYPTO_FIPS140_EXTMOD_SOURCE
+ - Regular mode: Uses freshly built kernel crypto implementation
+
+ For modular algorithms (e.g., aes.ko), they are not duplicated
+ automatically. Either make them built-in to be included into
+ fips140.ko for automatic duplication, or require OS utilities such
+ as `modprobe` to correctly isolate modular cryptos in filesystems.
+
+ If unsure, say N.
\ No newline at end of file
diff --git a/crypto/fips140/Makefile b/crypto/fips140/Makefile
index a4973c48dbe43..c3612c24df296 100644
--- a/crypto/fips140/Makefile
+++ b/crypto/fips140/Makefile
@@ -7,4 +7,7 @@ obj-y += fips140-loader.o
CFLAGS_fips140-fn-redirect.o += -I$(obj)
CFLAGS_fips140-module.o += -DFIPS140_CORE

-clean-files:= .fips140.order .fips140.symvers .fips140-fn-redirect.h .fips140.exported .fips140.hmac .fips140.ko.btf
\ No newline at end of file
+clean-files:= .fips140.order .fips140.symvers .fips140-fn-redirect.h .fips140.exported .fips140.hmac .fips140.ko.btf
+ifdef CONFIG_CRYPTO_FIPS140_DUAL_VERSION
+clean-files += .nonfips140.ko.btf
+endif
\ No newline at end of file
diff --git a/crypto/fips140/fips140-loader.c b/crypto/fips140/fips140-loader.c
index 9665ddb26e2d1..490fb7276befb 100644
--- a/crypto/fips140/fips140-loader.c
+++ b/crypto/fips140/fips140-loader.c
@@ -11,12 +11,20 @@
#include <linux/elf.h>
#include <linux/kthread.h>
#include <linux/wait.h>
+#include <linux/fips.h>

extern const u8 _binary_fips140_ko_start[];
extern const u8 _binary_fips140_ko_end[];
extern const u8 _binary_fips140_hmac_start[];
extern const u8 _binary_fips140_hmac_end[];

+#ifdef CONFIG_CRYPTO_FIPS140_DUAL_VERSION
+/* For non-FIPS mode: no module signature/HMAC is required,
+ * so only include binary start/end address without module sig address */
+extern const u8 _binary_nonfips140_ko_start[];
+extern const u8 _binary_nonfips140_ko_end[];
+#endif
+
const u8 *_binary_crypto_ko_start;
EXPORT_SYMBOL_GPL(_binary_crypto_ko_start);
const u8 *_binary_crypto_ko_end;
@@ -29,6 +37,10 @@ EXPORT_SYMBOL_GPL(_binary_crypto_hmac_end);
#ifdef CONFIG_DEBUG_INFO_BTF_MODULES
extern const u8 __start_fips140_btf[];
extern const u8 __stop_fips140_btf[];
+#ifdef CONFIG_CRYPTO_FIPS140_DUAL_VERSION
+extern const u8 __start_nonfips140_btf[];
+extern const u8 __stop_nonfips140_btf[];
+#endif
const u8 *__start_crypto_btf;
const u8 *__stop_crypto_btf;
#endif
@@ -47,6 +59,20 @@ static void load_prepare(void)
__start_crypto_btf = __start_fips140_btf;
__stop_crypto_btf = __stop_fips140_btf;
#endif
+
+#ifdef CONFIG_CRYPTO_FIPS140_DUAL_VERSION
+ if (!fips_enabled) {
+ _binary_crypto_ko_start = _binary_nonfips140_ko_start;
+ _binary_crypto_ko_end = _binary_nonfips140_ko_end;
+ _binary_crypto_hmac_start = NULL;
+ _binary_crypto_hmac_end = NULL;
+
+#ifdef CONFIG_DEBUG_INFO_BTF_MODULES
+ __start_crypto_btf = __start_nonfips140_btf;
+ __stop_crypto_btf = __stop_nonfips140_btf;
+#endif
+ }
+#endif
}

static int fips_loader_init(void)
diff --git a/scripts/Makefile.vmlinux b/scripts/Makefile.vmlinux
index b30d65f8b6b3d..996d016e518ca 100644
--- a/scripts/Makefile.vmlinux
+++ b/scripts/Makefile.vmlinux
@@ -81,7 +81,18 @@ ifdef CONFIG_DEBUG_INFO_BTF_MODULES
cp crypto/fips140/.fips140.ko.btf crypto/fips140/.fips140.ko.btf.first; \
rm -f crypto/fips140/fips140.ko.tmp; \
$(LD) -r -b binary -o crypto/fips140/fips140_btf.o crypto/fips140/.fips140.ko.btf; \
- $(OBJCOPY) --rename-section .data=.fips140_btf crypto/fips140/fips140_btf.o; \
+ $(OBJCOPY) --rename-section .data=.fips140_btf crypto/fips140/fips140_btf.o
+ifdef CONFIG_CRYPTO_FIPS140_DUAL_VERSION
+ cmd_link_vmlinux += ; \
+ cp crypto/fips140/fips140.ko crypto/fips140/nonfips140.ko.tmp; \
+ LLVM_OBJCOPY="$(OBJCOPY)" $(PAHOLE) -J $(PAHOLE_FLAGS) $(MODULE_PAHOLE_FLAGS) --btf_base $@ crypto/fips140/nonfips140.ko.tmp; \
+ $(RESOLVE_BTFIDS) -b $@ crypto/fips140/nonfips140.ko.tmp; \
+ $(OBJCOPY) --dump-section=.BTF=crypto/fips140/.nonfips140.ko.btf crypto/fips140/nonfips140.ko.tmp; \
+ rm -f crypto/fips140/nonfips140.ko.tmp; \
+ $(LD) -r -b binary -o crypto/fips140/nonfips140_btf.o crypto/fips140/.nonfips140.ko.btf; \
+ $(OBJCOPY) --rename-section .data=.nonfips140_btf --prefix-symbols nonfips140_ crypto/fips140/nonfips140_btf.o
+endif
+ cmd_link_vmlinux += ; \
rm -f $@; \
FIPS140_BTF_RELINK=1 $< "$(LD)" "$(KBUILD_LDFLAGS)" "$(LDFLAGS_vmlinux)" "$@"; \
cp $(fips140_build)/crypto/fips140/fips140.ko crypto/fips140/fips140.ko.tmp2; \
@@ -90,13 +101,27 @@ ifdef CONFIG_DEBUG_INFO_BTF_MODULES
$(OBJCOPY) --dump-section=.BTF=crypto/fips140/.fips140.ko.btf.second crypto/fips140/fips140.ko.tmp2; \
rm -f crypto/fips140/fips140.ko.tmp2; \
diff crypto/fips140/.fips140.ko.btf.first crypto/fips140/.fips140.ko.btf.second >/dev/null || echo "Module BTF differs"; \
- rm -f crypto/fips140/.fips140.ko.btf.first crypto/fips140/.fips140.ko.btf.second; \
+ rm -f crypto/fips140/.fips140.ko.btf.first crypto/fips140/.fips140.ko.btf.second
+ifdef CONFIG_CRYPTO_FIPS140_DUAL_VERSION
+ cmd_link_vmlinux += ; \
+ cp crypto/fips140/fips140.ko crypto/fips140/nonfips140.ko.tmp2; \
+ LLVM_OBJCOPY="$(OBJCOPY)" $(PAHOLE) -J $(PAHOLE_FLAGS) $(MODULE_PAHOLE_FLAGS) --btf_base $@ crypto/fips140/nonfips140.ko.tmp2; \
+ $(RESOLVE_BTFIDS) -b $@ crypto/fips140/nonfips140.ko.tmp2; \
+ $(OBJCOPY) --dump-section=.BTF=crypto/fips140/.nonfips140.ko.btf.second crypto/fips140/nonfips140.ko.tmp2; \
+ rm -f crypto/fips140/nonfips140.ko.tmp2; \
+ diff crypto/fips140/.nonfips140.ko.btf crypto/fips140/.nonfips140.ko.btf.second >/dev/null || echo "Nonfips140 Module BTF differs"; \
+ rm -f crypto/fips140/.nonfips140.ko.btf.second
+endif
+ cmd_link_vmlinux += ; \
$(if $(ARCH_POSTLINK), $(MAKE) -f $(ARCH_POSTLINK) $@, true)
endif
endif

ifdef CONFIG_CRYPTO_FIPS140_EXTMOD
fips140-deps := crypto/fips140/fips140-embedded.o crypto/fips140/fips140-digest.o
+ifdef CONFIG_CRYPTO_FIPS140_DUAL_VERSION
+fips140-deps += crypto/fips140/nonfips140-embedded.o
+endif
endif

targets += vmlinux.unstripped .vmlinux.export.o
diff --git a/scripts/link-vmlinux.sh b/scripts/link-vmlinux.sh
index de40d6bb3a93d..283e7e3316ef6 100755
--- a/scripts/link-vmlinux.sh
+++ b/scripts/link-vmlinux.sh
@@ -78,8 +78,14 @@ vmlinux_link()

if is_enabled CONFIG_CRYPTO_FIPS140_EXTMOD; then
objs="${objs} crypto/fips140/fips140-embedded.o crypto/fips140/fips140-digest.o"
+ if is_enabled CONFIG_CRYPTO_FIPS140_DUAL_VERSION; then
+ objs="${objs} crypto/fips140/nonfips140-embedded.o"
+ fi
if is_enabled CONFIG_DEBUG_INFO_BTF_MODULES && [ -n "${FIPS140_BTF_RELINK}" ] && [ -f crypto/fips140/fips140_btf.o ]; then
objs="${objs} crypto/fips140/fips140_btf.o"
+ if is_enabled CONFIG_CRYPTO_FIPS140_DUAL_VERSION && [ -f crypto/fips140/nonfips140_btf.o ]; then
+ objs="${objs} crypto/fips140/nonfips140_btf.o"
+ fi
fi
fi

--
2.47.3