On Mon, 2023-11-27 at 12:12 -0500, Violet Purcell wrote:
> Currently, using a custom path for MODULES_SIGN_KEY requires the key to
> be readable by portage:portage. This is not ideal for security, since
> the file has to be either owned by portage:portage or readable by all
> users in this case. Instead, export the contents of MODULES_SIGN_KEY to
> a variable in pkg_setup, and then create a temporary file with it in
> src_configure to ensure that the temporary key is readable by the user
> that the kernel is being built as. The variable is then unset so it does
> not end up in the final environment file.
>
> Signed-off-by: Violet Purcell <vimpro...@inventati.org>
> ---
> eclass/kernel-build.eclass | 19 +++++++++++++------
> 1 file changed, 13 insertions(+), 6 deletions(-)
>
> diff --git a/eclass/kernel-build.eclass b/eclass/kernel-build.eclass
> index 4f7e4d047739..cf958c86ff29 100644
> --- a/eclass/kernel-build.eclass
> +++ b/eclass/kernel-build.eclass
> @@ -114,6 +114,13 @@ kernel-build_pkg_setup() {
> python-any-r1_pkg_setup
> if [[ ${KERNEL_IUSE_MODULES_SIGN} ]]; then
> secureboot_pkg_setup
> + if [[ -e ${MODULES_SIGN_KEY} && ${MODULES_SIGN_KEY} != pkcs11:*
> ]]; then
> + if [[ -e ${MODULES_SIGN_CERT} && ${MODULES_SIGN_CERT}
> != ${MODULES_SIGN_KEY} ]]; then
> + export MODULES_SIGN_KEY_CONTENTS="$(cat
> "${MODULES_SIGN_CERT}" "${MODULES_SIGN_KEY}")"
> + else
> + export MODULES_SIGN_KEY_CONTENTS="$(<
> "${MODULES_SIGN_KEY}")"
You don't need to export it. Unexported variables are also preserved.
> + fi
> + fi
> fi
> }
>
> @@ -427,12 +434,12 @@ kernel-build_merge_configs() {
> CONFIG_MODULE_SIG_FORCE=y
> CONFIG_MODULE_SIG_${MODULES_SIGN_HASH^^}=y
> EOF
> - if [[ -e ${MODULES_SIGN_KEY} && -e ${MODULES_SIGN_CERT}
> &&
> - ${MODULES_SIGN_KEY} != ${MODULES_SIGN_CERT} &&
> - ${MODULES_SIGN_KEY} != pkcs11:* ]]
> - then
> - cat "${MODULES_SIGN_CERT}"
> "${MODULES_SIGN_KEY}" > "${T}/kernel_key.pem" || die
> - MODULES_SIGN_KEY="${T}/kernel_key.pem"
> + if [[ -n "${MODULES_SIGN_KEY_CONTENTS}" ]]; then
> + touch "${T}/kernel_key.pem" || die
> + chmod 0600 "${T}/kernel_key.pem" || die
This creates a race condition whereupon the file can be opened between
the call to touch and chmod. It's better to use a subshell and set
umask.
> + echo "${MODULES_SIGN_KEY_CONTENTS}" >
> "${T}/kernel_key.pem" || die
> + unset MODULES_SIGN_KEY_CONTENTS
> + export MODULES_SIGN_KEY="${T}/kernel_key.pem"
> fi
> if [[ ${MODULES_SIGN_KEY} == pkcs11:* || -r
> ${MODULES_SIGN_KEY} ]]; then
> echo
> "CONFIG_MODULE_SIG_KEY=\"${MODULES_SIGN_KEY}\"" \
--
Best regards,
Michał Górny
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