From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001 From: Jonathan Lebon Date: Wed, 17 Aug 2022 10:26:03 -0400 Subject: [PATCH] squish: BLS: only write /etc/kernel/cmdline if writable On OSTree systems, `grub2-mkconfig` is run with `/etc` mounted read-only because as part of the promise of transactional updates, we want to make sure that we're not modifying the current deployment's state (`/etc` or `/var`). This conflicts with 0837dcdf1 ("BLS: create /etc/kernel/cmdline during mkconfig") which wants to write to `/etc/kernel/cmdline`. I'm not exactly sure on the background there, but based on the comment I think the intent is to fulfill grubby's expectation that the file exists. However, in systems like Silverblue, kernel arguments are managed by the rpm-ostree stack and grubby is not shipped at all. Adjust the script slightly so that we only write `/etc/kernel/cmdline` if the parent directory is writable. In the future, we're hoping to simplify things further on rpm-ostree systems by not running `grub2-mkconfig` at all since libostree already directly writes BLS entries. Doing that would also have avoided this, but ratcheting it into existing systems needs more careful thought. Signed-off-by: Jonathan Lebon Fixes: https://github.com/fedora-silverblue/issue-tracker/issues/322 --- util/grub.d/10_linux.in | 13 +++++++------ 1 file changed, 7 insertions(+), 6 deletions(-) diff --git a/util/grub.d/10_linux.in b/util/grub.d/10_linux.in index 5d1fa072f2..4795a63b4c 100644 --- a/util/grub.d/10_linux.in +++ b/util/grub.d/10_linux.in @@ -161,12 +161,13 @@ update_bls_cmdline() local cmdline="root=${LINUX_ROOT_DEVICE} ro ${GRUB_CMDLINE_LINUX} ${GRUB_CMDLINE_LINUX_DEFAULT}" local -a files=($(get_sorted_bls)) - if [[ ! -f /etc/kernel/cmdline ]] || - [[ /etc/kernel/cmdline -ot /etc/default/grub ]]; then - # anaconda has the correct information to create this during install; - # afterward, grubby will take care of syncing on updates. If the user - # has modified /etc/default/grub, try to cope. - echo "$cmdline" > /etc/kernel/cmdline + if [ -w /etc/kernel ] && + [[ ! -f /etc/kernel/cmdline || + /etc/kernel/cmdline -ot /etc/default/grub ]]; then + # anaconda has the correct information to create this during install; + # afterward, grubby will take care of syncing on updates. If the user + # has modified /etc/default/grub, try to cope. + echo "$cmdline" > /etc/kernel/cmdline fi for bls in "${files[@]}"; do