Re: [gentoo-dev] [PATCH] linux-mod.eclass: support module signing

[Kenton Groombridge <concord@gentoo.org>]

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On 22/06/23 08:51AM, Mike Pagano wrote:
> On 6/21/22 14:21, Kenton Groombridge wrote:
> > On 22/06/21 02:19PM, Kenton Groombridge wrote:
> > > eee74b9fca1 adds support for module compression, but this breaks loading
> > > out of tree modules when module signing is enforced because modules must
> > > be signed before they are compressed. Additionally, the recommended
> > > Portage hook[1] no longer works with this change.
> > > 
> > 
> > Forgot to include this reference:
> > 
> > [1] https://wiki.gentoo.org/wiki/Signed_kernel_module_support#Automatically_signing_kernel_modules_.28Portage.29
> > 
> > > Add module signing support in linux-mod.eclass which more or less does
> > > exactly what the aforementioned Portage hook does. If the kernel
> > > configuration has CONFIG_MODULE_SIG_ALL=y, then read the hash and keys
> > > from the kernel configuration and call the sign_file tool to sign the
> > > module before it is compressed.
> > > 
> > > Bug: https://bugs.gentoo.org/show_bug.cgi?id=447352
> > > Signed-off-by: Kenton Groombridge <concord@gentoo.org>
> > > ---
> > >   eclass/linux-mod.eclass | 16 ++++++++++++++++
> > >   1 file changed, 16 insertions(+)
> > > 
> > > diff --git a/eclass/linux-mod.eclass b/eclass/linux-mod.eclass
> > > index b7c13cbf7e7..fd40f6d7c6c 100644
> > > --- a/eclass/linux-mod.eclass
> > > +++ b/eclass/linux-mod.eclass
> > > @@ -712,6 +712,22 @@ linux-mod_src_install() {
> > >   		cd "${objdir}" || die "${objdir} does not exist"
> > >   		insinto "${INSTALL_MOD_PATH}"/lib/modules/${KV_FULL}/${libdir}
> > > +		# check here for CONFIG_MODULE_SIG_ALL and sign the module being built if enabled.
> > > +		# modules must be signed before they are compressed.
> > > +
> > > +		if linux_chkconfig_present MODULE_SIG_ALL; then
> > > +			local module_sig_hash="$(linux_chkconfig_string MODULE_SIG_HASH)"
> > > +			local module_sig_key="$(linux_chkconfig_string MODULE_SIG_KEY)"
> > > +			module_sig_key="${module_sig_key:-certs/signing_key.pem}"
> > > +			if [[ "${module_sig_key#pkcs11:}" == "${module_sig_key}" && "${module_sig_key#/}" == "${module_sig_key}" ]]; then
> > > +				local key_path="${KERNEL_DIR}/${module_sig_key}"
> > > +			else
> > > +				local key_path="${module_sig_key}"
> > > +			fi
> > > +			local cert_path="${KERNEL_DIR}/certs/signing_key.x509"
> > > +			"${KERNEL_DIR}"/scripts/sign-file ${module_sig_hash//\"} ${key_path//\"} ${cert_path} ${modulename}.${KV_OBJ}
> > > +		fi
> > > +
> > >   		# check here for CONFIG_MODULE_COMPRESS_<compression option> (NONE, GZIP, XZ, ZSTD)
> > >   		# and similarily compress the module being built if != NONE.
> > > -- 
> > > 2.35.1
> > > 
> > > 
> 
> 
> First of all, thank-you for your work !
> I appreciate any assistance with enhancement or clean-up of these eclasses.
> 
> I tested your patch, are you signing the files in 'work' after they are installed in 'image' ?
> 
> 
> /usr/src/linux/scripts/extract-module-sig.pl -s ./work/kernel/nvidia.ko > /tmp/sig
> Read 47802433 bytes from module file
> Found magic number at 47802433
> Found PKCS#7/CMS encapsulation
> Found 681 bytes of signature [308202a506092a864886f70d010702a0]
> 
> /usr/src/linux/scripts/extract-module-sig.pl -s ./image/lib/modules/5.18.6-gentoo/video/nvidia.ko > /tmp/sig
> Read 47227784 bytes from module file
> Magic number not found at 47227784
> 

Thanks for testing!

That's odd. In my environment they are signed in 'work' before
installing to 'image' as they should be.

# unzstd /lib/modules/5.15.48-gentoo/misc/p_lkrg.ko.zst
/lib/modules/5.15.48-gentoo/misc/p_lkrg.ko.zst: 436681 bytes
# /usr/src/linux/scripts/extract-module-sig.pl -s /lib/modules/5.15.48-gentoo/misc/p_lkrg.ko >sig
Read 436681 bytes from module file
Found magic number at 436681
Found PKCS#7/CMS encapsulation
Found 681 bytes of signature [308202a506092a864886f70d010702a0]

The installation of modules in linux-mod_src_install happens after
signing and compression, so unless I am missing something that shouldn't
be happening.

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