From d4f2826410b34d50a6dae94c17f00727de5e99ed Mon Sep 17 00:00:00 2001 From: Linn Crosetto Date: Fri, 4 Mar 2016 16:08:24 -0700 Subject: [PATCH] acpi: Disable ACPI table override if securelevel is set From the kernel documentation (initrd_table_override.txt): If the ACPI_INITRD_TABLE_OVERRIDE compile option is true, it is possible to override nearly any ACPI table provided by the BIOS with an instrumented, modified one. When securelevel is set, the kernel should disallow any unauthenticated changes to kernel space. ACPI tables contain code invoked by the kernel, so do not allow ACPI tables to be overridden if securelevel is set. Signed-off-by: Linn Crosetto [bwh: Forward-ported to 4.7: ACPI override code moved to drivers/acpi/tables.c] [bwh: Forward-ported to 4.9: adjust context] Gbp-Pq: Topic features/all/securelevel Gbp-Pq: Name acpi-disable-acpi-table-override-if-securelevel-is-s.patch --- arch/x86/kernel/setup.c | 12 ++++++------ drivers/acpi/tables.c | 7 +++++++ 2 files changed, 13 insertions(+), 6 deletions(-) diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c index c1922b2072ec..1eded5d9b5d1 100644 --- a/arch/x86/kernel/setup.c +++ b/arch/x86/kernel/setup.c @@ -1160,6 +1160,12 @@ void __init setup_arch(char **cmdline_p) /* Allocate bigger log buffer */ setup_log_buf(1); +#ifdef CONFIG_EFI_SECURE_BOOT_SECURELEVEL + if (boot_params.secure_boot) { + set_securelevel(1); + } +#endif + reserve_initrd(); acpi_table_upgrade(); @@ -1168,12 +1174,6 @@ void __init setup_arch(char **cmdline_p) io_delay_init(); -#ifdef CONFIG_EFI_SECURE_BOOT_SECURELEVEL - if (boot_params.secure_boot) { - set_securelevel(1); - } -#endif - /* * Parse the ACPI tables for possible boot-time SMP configuration. */ diff --git a/drivers/acpi/tables.c b/drivers/acpi/tables.c index cdd56c4657e0..1d493f12eea6 100644 --- a/drivers/acpi/tables.c +++ b/drivers/acpi/tables.c @@ -35,6 +35,7 @@ #include #include #include +#include #include "internal.h" #ifdef CONFIG_ACPI_CUSTOM_DSDT @@ -545,6 +546,12 @@ void __init acpi_table_upgrade(void) if (table_nr == 0) return; + if (get_securelevel() > 0) { + pr_notice(PREFIX + "securelevel enabled, ignoring table override\n"); + return; + } + acpi_tables_addr = memblock_find_in_range(0, ACPI_TABLE_UPGRADE_MAX_PHYS, all_tables_size, PAGE_SIZE); -- 2.30.2