linux-kernel - Re: [PATCH] MODSIGN: Only sign modules if built in-tree

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Date:	Thu, 01 Nov 2012 17:38:15 +1030
From:	Rusty Russell <rusty@...tcorp.com.au>
To:	Josh Boyer <jwboyer@...hat.com>
Cc:	Bruno Wolff III <bruno@...ff.to>, dhowells@...hat.com,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] MODSIGN: Only sign modules if built in-tree

Josh Boyer <jwboyer@...hat.com> writes:
> When building out-of-tree modules, the current modules_install target
> will attempt to sign them if module signing is enabled.  This will only
> work if the signing keys are present in the build tree.  That will
> often not be the case for modules that are built out-of-tree against
> distribution kernel development packages.  This distros will not include
> the signing keys, and build errors such as:
>
>     INSTALL /home/bruno/rpmbuild/BUILD/dahdi-linux-2.6.1/drivers/dahdi/dahdi_dyamic_eth.ko
>     Can't read private key
>     make[2]: *** [/home/bruno/rpmbuild/BUILD/dahdi-linux-2.6.1/drivers/dahdi/dahdi_dynamic.ko] Error 2
>
> will prevent such modules from successfully being installed.  This changes
> the mod_sign_cmd to only sign the modules if they are built in-tree.  Those
> built externally can sign them manually.

I prefer something like this (untested):

diff --git a/Makefile b/Makefile
index 42d0e56..cb66c8d 100644
--- a/Makefile
+++ b/Makefile
@@ -722,8 +722,14 @@ export mod_strip_cmd
 ifeq ($(CONFIG_MODULE_SIG),y)
 MODSECKEY = ./signing_key.priv
 MODPUBKEY = ./signing_key.x509
+ifeq ($(KBUILD_EXTMOD),)
+SIGNFAIL = false
+else
+# External builds might not have a signing key, don't break module_install.
+SIGNFAIL = true
+endif # KBUILD_EXTMOD
 export MODPUBKEY
-mod_sign_cmd = perl $(srctree)/scripts/sign-file $(MODSECKEY) $(MODPUBKEY)
+mod_sign_cmd = perl $(srctree)/scripts/sign-file $(MODSECKEY) $(MODPUBKEY) || $(SIGNFAIL)
 else
 mod_sign_cmd = true
 endif
--
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