This is a note to let you know that I've just added the patch titled
ACPI: configfs: Disallow loading ACPI tables when locked down
to the 5.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
acpi-configfs-disallow-loading-acpi-tables-when-locked-down.patch
and it can be found in the queue-5.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 75b0cea7bf307f362057cc778efe89af4c615354 Mon Sep 17 00:00:00 2001
From: "Jason A. Donenfeld" <Jason@xxxxxxxxx>
Date: Mon, 15 Jun 2020 04:43:32 -0600
Subject: ACPI: configfs: Disallow loading ACPI tables when locked down
From: Jason A. Donenfeld <Jason@xxxxxxxxx>
commit 75b0cea7bf307f362057cc778efe89af4c615354 upstream.
Like other vectors already patched, this one here allows the root
user to load ACPI tables, which enables arbitrary physical address
writes, which in turn makes it possible to disable lockdown.
Prevents this by checking the lockdown status before allowing a new
ACPI table to be installed. The link in the trailer shows a PoC of
how this might be used.
Link: https://git.zx2c4.com/american-unsigned-language/tree/american-unsigned-language-2.sh
Cc: 5.4+ <stable@xxxxxxxxxxxxxxx> # 5.4+
Signed-off-by: Jason A. Donenfeld <Jason@xxxxxxxxx>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/acpi/acpi_configfs.c | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)
--- a/drivers/acpi/acpi_configfs.c
+++ b/drivers/acpi/acpi_configfs.c
@@ -11,6 +11,7 @@
#include <linux/module.h>
#include <linux/configfs.h>
#include <linux/acpi.h>
+#include <linux/security.h>
#include "acpica/accommon.h"
#include "acpica/actables.h"
@@ -28,7 +29,10 @@ static ssize_t acpi_table_aml_write(stru
{
const struct acpi_table_header *header = data;
struct acpi_table *table;
- int ret;
+ int ret = security_locked_down(LOCKDOWN_ACPI_TABLES);
+
+ if (ret)
+ return ret;
table = container_of(cfg, struct acpi_table, cfg);
Patches currently in stable-queue which might be from Jason@xxxxxxxxx are
queue-5.4/acpi-configfs-disallow-loading-acpi-tables-when-locked-down.patch
