acpi: Disable APEI error injection if securelevel is set

ACPI provides an error injection mechanism, EINJ, for debugging and testing
the ACPI Platform Error Interface (APEI) and other RAS features. If
supported by the firmware, ACPI specification 5.0 and later provide for a
way to specify a physical memory address to which to inject the error.

Injecting errors through EINJ can produce errors which to the platform are
indistinguishable from real hardware errors. This can have undesirable
side-effects, such as causing the platform to mark hardware as needing
replacement.

While it does not provide a method to load unauthenticated privileged code,
the effect of these errors may persist across reboots and affect trust in
the underlying hardware, so disable error injection through EINJ if
securelevel is set.

Signed-off-by: Linn Crosetto <linn@hpe.com>
Gbp-Pq: Topic features/all/securelevel
Gbp-Pq: Name acpi-disable-apei-error-injection-if-securelevel-is-.patch

diff --git a/drivers/acpi/apei/einj.c b/drivers/acpi/apei/einj.c
index eebb7e39c49c7c94dd9f31b0d5d992d323a62c63..604d9ff5c22716982aea0e0d5e05b9547991005a 100644 (file)
--- a/drivers/acpi/apei/einj.c
+++ b/drivers/acpi/apei/einj.c
@@ -29,6 +29,7 @@
 #include <linux/nmi.h>
 #include <linux/delay.h>
 #include <linux/mm.h>
+#include <linux/security.h>
 #include <asm/unaligned.h>
 
 #include "apei-internal.h"
@@ -518,6 +519,9 @@ static int einj_error_inject(u32 type, u32 flags, u64 param1, u64 param2,
        int rc;
        u64 base_addr, size;
 
+       if (get_securelevel() > 0)
+               return -EPERM;
+
        /* If user manually set "flags", make sure it is legal */
        if (flags && (flags &
                ~(SETWA_FLAGS_APICID|SETWA_FLAGS_MEM|SETWA_FLAGS_PCIE_SBDF)))