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

[Mike Pagano <mpagano@gentoo.org>]

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



Mike




-- 
Mike Pagano
Gentoo Developer - Kernel Project
Gentoo Sources - Lead
E-Mail     : mpagano@gentoo.org
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