linux/fs/efivarfs
Luck, Tony bef3efbeb8 efivarfs: Limit the rate for non-root to read files
Each read from a file in efivarfs results in two calls to EFI
(one to get the file size, another to get the actual data).

On X86 these EFI calls result in broadcast system management
interrupts (SMI) which affect performance of the whole system.
A malicious user can loop performing reads from efivarfs bringing
the system to its knees.

Linus suggested per-user rate limit to solve this.

So we add a ratelimit structure to "user_struct" and initialize
it for the root user for no limit. When allocating user_struct for
other users we set the limit to 100 per second. This could be used
for other places that want to limit the rate of some detrimental
user action.

In efivarfs if the limit is exceeded when reading, we take an
interruptible nap for 50ms and check the rate limit again.

Signed-off-by: Tony Luck <tony.luck@intel.com>
Acked-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-02-22 10:21:02 -08:00
..
file.c efivarfs: Limit the rate for non-root to read files 2018-02-22 10:21:02 -08:00
inode.c Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2016-10-10 20:16:43 -07:00
internal.h efi: Make efivarfs entries immutable by default 2016-02-10 16:25:52 +00:00
Kconfig fs: Make efivarfs a pseudo filesystem, built by default with EFI 2015-01-05 14:15:58 +00:00
Makefile efivarfs: Move to fs/efivarfs 2013-04-17 13:25:09 +01:00
super.c VFS: Kill off s_options and helpers 2017-07-11 06:09:21 -04:00