commit 7c7642530fab73facaf3eac233cfbce29e10b0ef Author: Peter Jones Date: Thu Nov 17 12:31:31 2022 -0500 Enable the NX compatibility flag by default. Currently by default, when we build shim we do not set the PE NX-compatibility DLL Characteristic flag. This signifies to the firmware that shim (including the components it loads) is not prepared for several related firmware changes: - non-executable stack - non-executable pages from AllocatePages()/AllocatePool()/etc. - non-writable 0 page (not strictly related but some firmware will be transitioning at the same time) - the need to use the UEFI 2.10 Memory Attribute Protocol to set page permissions. This patch changes that default to be enabled by default. Distributors of shim will need to ensure that either their builds disable this bit (using "post-process-pe -N"), or that the bootloaders and kernels you support loading are all compliant with this change. A new make variable, POST_PROCESS_PE_FLAGS, has been added to simplify doing so. Signed-off-by: Peter Jones diff --git a/BUILDING b/BUILDING index 3b2e85d3..17cd98d3 100644 --- a/BUILDING +++ b/BUILDING @@ -78,6 +78,9 @@ Variables you could set to customize the build: - OSLABEL This is the label that will be put in BOOT$(EFI_ARCH).CSV for your OS. By default this is the same value as EFIDIR . +- POST_PROCESS_PE_FLAGS + This allows you to add flags to the invocation of "post-process-pe", for + example to disable the NX compatibility flag. Vendor SBAT data: It will sometimes be requested by reviewers that a build includes extra diff --git a/Make.defaults b/Make.defaults index c46164a3..9af89f4e 100644 --- a/Make.defaults +++ b/Make.defaults @@ -139,6 +139,8 @@ CFLAGS = $(FEATUREFLAGS) \ $(INCLUDES) \ $(DEFINES) +POST_PROCESS_PE_FLAGS = + ifneq ($(origin OVERRIDE_SECURITY_POLICY), undefined) DEFINES += -DOVERRIDE_SECURITY_POLICY endif diff --git a/Makefile b/Makefile index a9202f46..f0f53f8f 100644 --- a/Makefile +++ b/Makefile @@ -255,7 +255,7 @@ endif -j .rela* -j .dyn -j .reloc -j .eh_frame \ -j .vendor_cert -j .sbat -j .sbatlevel \ $(FORMAT) $< $@ - ./post-process-pe -vv $@ + ./post-process-pe -vv $(POST_PROCESS_PE_FLAGS) $@ ifneq ($(origin ENABLE_SHIM_HASH),undefined) %.hash : %.efi diff --git a/post-process-pe.c b/post-process-pe.c index de8f4a38..f39fdddf 100644 --- a/post-process-pe.c +++ b/post-process-pe.c @@ -42,7 +42,7 @@ static int verbosity; 0; \ }) -static bool set_nx_compat = false; +static bool set_nx_compat = true; typedef uint8_t UINT8; typedef uint16_t UINT16;