From f1e9e2b062fab46a6e3aec1f08d4554dd5dd2b98 Mon Sep 17 00:00:00 2001
From: Marvin Häuser
Date: Thu, 8 Apr 2021 20:04:16 +0200
Subject: [efi] Align EFI image sections by page size

For optimal memory permission management, PE sections need to be
aligned by the platform's minimum page size.  Currently, the PE
section alignment is fixed to 32 bytes, which is below the typical 4kB
page size.  Align all sections to 4kB and adjust ELF to PE image
conversion accordingly.

Signed-off-by: Marvin Häuser <mhaeuser@posteo.de>
---
 src/util/elf2efi.c | 35 ++++++++++++++++++++++++-----------
 1 file changed, 24 insertions(+), 11 deletions(-)

(limited to 'src/util')

diff --git a/src/util/elf2efi.c b/src/util/elf2efi.c
index 38eb29964..b0d546645 100644
--- a/src/util/elf2efi.c
+++ b/src/util/elf2efi.c
@@ -125,7 +125,8 @@
 #define R_ARM_V4BX 40
 #endif
 
-#define EFI_FILE_ALIGN 0x20
+#define EFI_FILE_ALIGN  0x20
+#define EFI_IMAGE_ALIGN 0x1000
 
 struct elf_file {
 	void *data;
@@ -173,9 +174,9 @@ static struct pe_header efi_pe_header = {
 			.Magic = EFI_IMAGE_NT_OPTIONAL_HDR_MAGIC,
 			.MajorLinkerVersion = 42,
 			.MinorLinkerVersion = 42,
-			.SectionAlignment = EFI_FILE_ALIGN,
+			.SectionAlignment = EFI_IMAGE_ALIGN,
 			.FileAlignment = EFI_FILE_ALIGN,
-			.SizeOfImage = sizeof ( efi_pe_header ),
+			.SizeOfImage = EFI_IMAGE_ALIGN,
 			.SizeOfHeaders = sizeof ( efi_pe_header ),
 			.NumberOfRvaAndSizes =
 				EFI_IMAGE_NUMBER_OF_DIRECTORY_ENTRIES,
@@ -216,6 +217,16 @@ static unsigned long efi_file_align ( unsigned long offset ) {
 	return ( ( offset + EFI_FILE_ALIGN - 1 ) & ~( EFI_FILE_ALIGN - 1 ) );
 }
 
+/**
+ * Align section within PE image
+ *
+ * @v offset		Unaligned offset
+ * @ret aligned_offset	Aligned offset
+ */
+static unsigned long efi_image_align ( unsigned long offset ) {
+	return ( ( offset + EFI_IMAGE_ALIGN - 1 ) & ~( EFI_IMAGE_ALIGN - 1 ) );
+}
+
 /**
  * Generate entry in PE relocation table
  *
@@ -605,7 +616,7 @@ static struct pe_section * process_section ( struct elf_file *elf,
 	pe_header->nt.FileHeader.NumberOfSections++;
 	pe_header->nt.OptionalHeader.SizeOfHeaders += sizeof ( new->hdr );
 	pe_header->nt.OptionalHeader.SizeOfImage =
-		efi_file_align ( data_end );
+		efi_image_align ( data_end );
 
 	return new;
 }
@@ -728,13 +739,15 @@ static struct pe_section *
 create_reloc_section ( struct pe_header *pe_header,
 		       struct pe_relocs *pe_reltab ) {
 	struct pe_section *reloc;
+	size_t section_rawsz;
 	size_t section_memsz;
 	size_t section_filesz;
 	EFI_IMAGE_DATA_DIRECTORY *relocdir;
 
 	/* Allocate PE section */
-	section_memsz = output_pe_reltab ( pe_reltab, NULL );
-	section_filesz = efi_file_align ( section_memsz );
+	section_rawsz = output_pe_reltab ( pe_reltab, NULL );
+	section_filesz = efi_file_align ( section_rawsz );
+	section_memsz = efi_image_align ( section_rawsz );
 	reloc = xmalloc ( sizeof ( *reloc ) + section_filesz );
 	memset ( reloc, 0, sizeof ( *reloc ) + section_filesz );
 
@@ -754,11 +767,11 @@ create_reloc_section ( struct pe_header *pe_header,
 	/* Update file header details */
 	pe_header->nt.FileHeader.NumberOfSections++;
 	pe_header->nt.OptionalHeader.SizeOfHeaders += sizeof ( reloc->hdr );
-	pe_header->nt.OptionalHeader.SizeOfImage += section_filesz;
+	pe_header->nt.OptionalHeader.SizeOfImage += section_memsz;
 	relocdir = &(pe_header->nt.OptionalHeader.DataDirectory
 		     [EFI_IMAGE_DIRECTORY_ENTRY_BASERELOC]);
 	relocdir->VirtualAddress = reloc->hdr.VirtualAddress;
-	relocdir->Size = reloc->hdr.Misc.VirtualSize;
+	relocdir->Size = section_rawsz;
 
 	return reloc;
 }
@@ -796,8 +809,8 @@ create_debug_section ( struct pe_header *pe_header, const char *filename ) {
 	} *contents;
 
 	/* Allocate PE section */
-	section_memsz = sizeof ( *contents );
-	section_filesz = efi_file_align ( section_memsz );
+	section_memsz = efi_image_align ( sizeof ( *contents ) );
+	section_filesz = efi_file_align ( sizeof ( *contents ) );
 	debug = xmalloc ( sizeof ( *debug ) + section_filesz );
 	memset ( debug, 0, sizeof ( *debug ) + section_filesz );
 	contents = ( void * ) debug->contents;
@@ -828,7 +841,7 @@ create_debug_section ( struct pe_header *pe_header, const char *filename ) {
 	/* Update file header details */
 	pe_header->nt.FileHeader.NumberOfSections++;
 	pe_header->nt.OptionalHeader.SizeOfHeaders += sizeof ( debug->hdr );
-	pe_header->nt.OptionalHeader.SizeOfImage += section_filesz;
+	pe_header->nt.OptionalHeader.SizeOfImage += section_memsz;
 	debugdir = &(pe_header->nt.OptionalHeader.DataDirectory
 		     [EFI_IMAGE_DIRECTORY_ENTRY_DEBUG]);
 	debugdir->VirtualAddress = debug->hdr.VirtualAddress;
-- 
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