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From f1fa90d02f50078a89da602d73dc9ab7743439ba Mon Sep 17 00:00:00 2001
From: Josh Boyer <>
Date: Mon, 24 Sep 2012 10:46:36 -0400
Subject: [PATCH 2/2] MODSIGN: Add modules_sign make target

If CONFIG_MODULE_SIG is set, and 'make modules_sign' is called then this
patch will cause the modules to get a signature installed.  The make target
is intended to be run after 'make modules_install', and will modify the
modules in-place in the installed location.

The signature will be appended to the module, along with some information
about the signature size and a magic string that indicates the presence of
the signature.  This requires private and public keys to be available.  By
default these are expected to be found in files:


in the base directory of the build.  The first is the private key in PEM
form and the second is the X.509 certificate in DER form as can be generated
from openssl:

    openssl req \
            -new -x509 -outform PEM -out signing_key.x509 \
            -keyout signing_key.priv -nodes \
            -subj "/CN=H2G2/O=Magrathea/CN=Slartibartfast"

If the secret key is not found then signing will be skipped and the unsigned
module from (1) will just be copied to foo.ko.

If signing occurs, lines like the following will be seen:

        SIGN [M] <install path>/fs/foo/foo.ko

will appear in the build log.  If the signature step will be skipped and the
following will be seen:

        NO SIGN [M] <install path>/fs/foo/foo.ko

NOTE!  After the signature step, the signed module must not be passed through
strip.  If you wish to strip or otherwise modify the kernel modules, use the
built-in stripping capabilities with 'make modules_install' or perform said
modifications before calling this make target.  This restriction may affect
packaging tools (such as rpmbuild) and initramfs composition tools.

Based heavily on work by: David Howells <>
Signed-off-by: Josh Boyer <>
 Makefile                 |  6 ++++++
 scripts/Makefile.modsign | 32 ++++++++++++++++++++++++++++++++
 2 files changed, 38 insertions(+)
 create mode 100644 scripts/Makefile.modsign

diff --git a/Makefile b/Makefile
index 89a2e2c..ac04c11 100644
--- a/Makefile
+++ b/Makefile
@@ -981,6 +981,12 @@ _modinst_post: _modinst_
 	$(Q)$(MAKE) -f $(srctree)/scripts/Makefile.fwinst obj=firmware __fw_modinst
 	$(call cmd,depmod)
+ifeq ($(CONFIG_MODULE_SIG), y)
+PHONY += modules_sign
+	$(Q)$(MAKE) -f $(srctree)/scripts/Makefile.modsign
 # Modules not configured
diff --git a/scripts/Makefile.modsign b/scripts/Makefile.modsign
new file mode 100644
index 0000000..670d5dc
--- /dev/null
+++ b/scripts/Makefile.modsign
@@ -0,0 +1,32 @@
+# ==========================================================================
+# Signing modules
+# ==========================================================================
+PHONY := __modsign
+include scripts/Kbuild.include
+__modules := $(sort $(shell grep -h '\.ko' /dev/null $(wildcard $(MODVERDIR)/*.mod)))
+modules := $(patsubst %.o,%.ko,$(wildcard $(__modules:.ko=.o)))
+PHONY += $(modules)
+__modsign: $(modules)
+	@:
+quiet_cmd_sign_ko = SIGN [M] $(2)/$(notdir $@)
+        cmd_sign_ko = $(mod_sign_cmd) $(2)/$(notdir $@)
+# Modules built outside the kernel source tree go into extra by default
+ext-mod-dir = $(INSTALL_MOD_DIR)$(subst $(patsubst %/,%,$(KBUILD_EXTMOD)),,$(@D))
+modinst_dir = $(if $(KBUILD_EXTMOD),$(ext-mod-dir),kernel/$(@D))
+	$(call cmd,sign_ko,$(MODLIB)/$(modinst_dir))
+# Declare the contents of the .PHONY variable as phony.  We keep that
+# # information in a variable se we can use it in if_changed and friends.