Messages in this thread | | | From | Joe Konno <> | Subject | [PATCH 0/2] efivars: reading variables can generate SMIs | Date | Thu, 15 Feb 2018 10:22:06 -0800 |
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From: Joe Konno <joe.konno@intel.com>
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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