From: Joe Konno <joe.konno@xxxxxxxxx>
It was pointed out that normal, unprivileged users reading certain EFI
variables (through efivarfs) can generate SMIs. Given these nodes are created
with 0644 permissions, normal users could generate a lot of SMIs. By
restricting permissions a bit (patch 1), we can make it harder for normal users
to generate spurious SMIs.
A normal user could generate lots of SMIs by reading the efivarfs in a trivial
loop:
```
while true; do
cat /sys/firmware/efi/evivars/* > /dev/null
done
```
Patch 1 in this series limits read and write permissions on efivarfs to the
owner/superuser. Group and world cannot access.
Patch 2 is for consistency and hygiene. If we restrict permissions for either
efivarfs or efi/vars, the other interface should get the same treatment.
Joe Konno (2):
fs/efivarfs: restrict inode permissions
efi: restrict top-level attribute permissions
drivers/firmware/efi/efi.c | 10 ++++++----
fs/efivarfs/super.c | 4 ++--
2 files changed, 8 insertions(+), 6 deletions(-)
--
2.14.1
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