On Thu, 16 Jun 2022 at 18:20, Kees Cook keescook@chromium.org wrote:
On Thu, Jun 16, 2022 at 02:47:40PM +0200, Ard Biesheuvel wrote:
Commit 5d9db883761a ("efi: Add support for a UEFI variable filesystem") dated Oct 5, 2012, introduced a new efivarfs pseudo-filesystem to replace the efivars sysfs interface that was used up to that point to expose EFI variables to user space.
The main problem with the sysfs interface was that it only supported up to 1024 bytes of payload per file, whereas the underlying variables themselves are only bounded by a platform specific per-variable and global limit that is typically much higher than 1024 bytes.
The deprecated sysfs interface is only enabled on x86 and Itanium, other EFI enabled architectures only support the efivarfs pseudo-filesystem.
Does anything still use the sysfs interface? (e.g. do paths to it exist in anything meaningful in, say, a Debian code search?)
All the hits I get there are in code that refers to /sys/firmware/efi/vars as the 'legacy' path, and also carries a reference to efivarfs. (i.e., /sys/firmware/efi/efivars)