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    SubjectRe: [PATCH 0/2] efivars: reading variables can generate SMIs
    On 15 February 2018 at 18:22, Joe Konno <joe.konno@linux.intel.com> wrote:
    > 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.
    >

    I am inclined to apply this as a fix, but I will give the x86 guys a
    chance to respond as well.


    > 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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