From 1957a85b0032a81e6482ca4aab883643b8dae06e Mon Sep 17 00:00:00 2001 From: Matthew Garrett Date: Mon, 19 Aug 2019 17:18:04 -0700 Subject: efi: Restrict efivar_ssdt_load when the kernel is locked down efivar_ssdt_load allows the kernel to import arbitrary ACPI code from an EFI variable, which gives arbitrary code execution in ring 0. Prevent that when the kernel is locked down. Signed-off-by: Matthew Garrett Acked-by: Ard Biesheuvel Reviewed-by: Kees Cook Cc: Ard Biesheuvel Cc: linux-efi@vger.kernel.org Signed-off-by: James Morris --- drivers/firmware/efi/efi.c | 6 ++++++ 1 file changed, 6 insertions(+) (limited to 'drivers/firmware') diff --git a/drivers/firmware/efi/efi.c b/drivers/firmware/efi/efi.c index 4b7cf7bc0ded..5f98374f77f4 100644 --- a/drivers/firmware/efi/efi.c +++ b/drivers/firmware/efi/efi.c @@ -30,6 +30,7 @@ #include #include #include +#include #include @@ -241,6 +242,11 @@ static void generic_ops_unregister(void) static char efivar_ssdt[EFIVAR_SSDT_NAME_MAX] __initdata; static int __init efivar_ssdt_setup(char *str) { + int ret = security_locked_down(LOCKDOWN_ACPI_TABLES); + + if (ret) + return ret; + if (strlen(str) < sizeof(efivar_ssdt)) memcpy(efivar_ssdt, str, strlen(str)); else -- cgit v1.2.3-59-g8ed1b