Commit 3c66bb19 authored by Ard Biesheuvel's avatar Ard Biesheuvel

arm64: efi: Set NX compat flag in PE/COFF header

The PE/COFF header has a NX compat flag which informs the firmware that
the application does not rely on memory regions being mapped with both
executable and writable permissions at the same time.

This is typically used by the firmware to decide whether it can set the
NX attribute on all allocations it returns, but going forward, it may be
used to enforce a policy that only permits applications with the NX flag
set to be loaded to begin wiht in some configurations, e.g., when Secure
Boot is in effect.

Even though the arm64 version of the EFI stub may relocate the kernel
before executing it, it always did so after disabling the MMU, and so we
were always in line with what the NX compat flag conveys, we just never
bothered to set it.

So let's set the flag now.

Cc: <stable@vger.kernel.org>
Signed-off-by: default avatarArd Biesheuvel <ardb@kernel.org>
parent 3c60f67b
...@@ -66,7 +66,7 @@ ...@@ -66,7 +66,7 @@
.long .Lefi_header_end - .L_head // SizeOfHeaders .long .Lefi_header_end - .L_head // SizeOfHeaders
.long 0 // CheckSum .long 0 // CheckSum
.short IMAGE_SUBSYSTEM_EFI_APPLICATION // Subsystem .short IMAGE_SUBSYSTEM_EFI_APPLICATION // Subsystem
.short 0 // DllCharacteristics .short IMAGE_DLL_CHARACTERISTICS_NX_COMPAT // DllCharacteristics
.quad 0 // SizeOfStackReserve .quad 0 // SizeOfStackReserve
.quad 0 // SizeOfStackCommit .quad 0 // SizeOfStackCommit
.quad 0 // SizeOfHeapReserve .quad 0 // SizeOfHeapReserve
......
Markdown is supported
0%
or
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment