path: root/Documentation
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authorPeter Jones <pjones@redhat.com>2016-02-08 14:48:15 -0500
committerSasha Levin <sasha.levin@oracle.com>2016-04-12 17:06:28 -0400
commit0dc03db627e3e900f329ba34f827be27851f1d7b (patch)
tree2f89895e701ad8c965ac43a8ebf6abeeb12ad888 /Documentation
parent414f7950ec63762b79a1738c5c5de76809d3ce1e (diff)
efi: Make efivarfs entries immutable by default
[ Upstream commit ed8b0de5a33d2a2557dce7f9429dca8cb5bc5879 ] "rm -rf" is bricking some peoples' laptops because of variables being used to store non-reinitializable firmware driver data that's required to POST the hardware. These are 100% bugs, and they need to be fixed, but in the mean time it shouldn't be easy to *accidentally* brick machines. We have to have delete working, and picking which variables do and don't work for deletion is quite intractable, so instead make everything immutable by default (except for a whitelist), and make tools that aren't quite so broad-spectrum unset the immutable flag. Signed-off-by: Peter Jones <pjones@redhat.com> Tested-by: Lee, Chun-Yi <jlee@suse.com> Acked-by: Matthew Garrett <mjg59@coreos.com> Signed-off-by: Matt Fleming <matt@codeblueprint.co.uk> Signed-off-by: Sasha Levin <sasha.levin@oracle.com>
Diffstat (limited to 'Documentation')
1 files changed, 7 insertions, 0 deletions
diff --git a/Documentation/filesystems/efivarfs.txt b/Documentation/filesystems/efivarfs.txt
index c477af086e65..686a64bba775 100644
--- a/Documentation/filesystems/efivarfs.txt
+++ b/Documentation/filesystems/efivarfs.txt
@@ -14,3 +14,10 @@ filesystem.
efivarfs is typically mounted like this,
mount -t efivarfs none /sys/firmware/efi/efivars
+Due to the presence of numerous firmware bugs where removing non-standard
+UEFI variables causes the system firmware to fail to POST, efivarfs
+files that are not well-known standardized variables are created
+as immutable files. This doesn't prevent removal - "chattr -i" will work -
+but it does prevent this kind of failure from being accomplished