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ImageTool: Prefer ELF PIE over object file relocations

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This commit is contained in:
Marvin Häuser 2023-04-15 18:25:21 +02:00 committed by Marvin Häuser
parent dac1ed6cb9
commit 92bb32130b
1 changed files with 54 additions and 56 deletions
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90
BaseTools/ImageTool/ElfScan.c
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@ -8,6 +8,7 @@
static Elf_Ehdr *mEhdr = NULL;
static Elf_Size mPeAlignment = 0x0;
static Elf_Addr mBaseAddress = 0x0;
static bool mHasPieRelocs = FALSE;
#if defined (_MSC_EXTENSIONS)
#define EFI_IMAGE_MACHINE_IA32 0x014C
@ -228,6 +229,10 @@ ParseElfFile (
fprintf (stderr, "ImageTool: ELF %d-th section's sh_info is out of range\n", Index);
return RETURN_VOLUME_CORRUPTED;
}
if (Shdr->sh_info == 0) {
mHasPieRelocs = TRUE;
}
}
if (Shdr->sh_addr < mBaseAddress) {
@ -268,6 +273,38 @@ ParseElfFile (
return RETURN_SUCCESS;
}
static
bool
ProcessRelocSection (
const Elf_Shdr *Shdr
)
{
const Elf_Shdr *SecShdr;
//
// PIE relocations will target dummy section 0.
//
if (Shdr->sh_info != 0) {
//
// If PIE relocations exist, prefer them.
//
if (mHasPieRelocs) {
return FALSE;
}
//
// Only translate relocations targetting sections that are translated.
//
SecShdr = GetShdrByIndex (Shdr->sh_info);
if (!IsShdrLoadable (SecShdr)) {
return FALSE;
}
} else {
assert (mHasPieRelocs);
}
return TRUE;
}
static
RETURN_STATUS
SetRelocs (
@ -276,14 +313,9 @@ SetRelocs (
{
UINT32 Index;
const Elf_Shdr *RelShdr;
const Elf_Shdr *SecShdr;
UINTN RelIdx;
const Elf_Rela *Rel;
UINT32 RelNum;
#if defined(EFI_TARGET64)
UINT32 Index2;
BOOLEAN New;
#endif
RelNum = 0;
for (Index = 0; Index < mEhdr->e_shnum; Index++) {
@ -293,19 +325,9 @@ SetRelocs (
continue;
}
//
// PIE relocations will target dummy section 0.
//
if (RelShdr->sh_info != 0) {
//
// Only translate relocations targetting sections that are translated.
//
SecShdr = GetShdrByIndex (RelShdr->sh_info);
if (!IsShdrLoadable (SecShdr)) {
if (!ProcessRelocSection (RelShdr)) {
continue;
}
}
for (RelIdx = 0; RelIdx < RelShdr->sh_size; RelIdx += (UINTN)RelShdr->sh_entsize) {
Rel = (Elf_Rela *)((UINT8 *)mEhdr + RelShdr->sh_offset + RelIdx);
@ -321,28 +343,9 @@ SetRelocs (
break;
case R_X86_64_RELATIVE:
case R_X86_64_64:
//
// If this is a ET_DYN (PIE) executable, we will encounter a dynamic SHT_RELA
// section that applies to the entire binary, and which will have its section
// index set to #0 (which is a NULL section with the SHF_ALLOC bit cleared).
//
// This RELA section will contain redundant R_xxx_RELATIVE relocations, one
// for every R_xxx_xx64 relocation appearing in the per-section RELA sections.
// (i.e., .rela.text and .rela.data) and .got entries' addresses (G + GOT).
//
New = TRUE;
for (Index2 = 0; Index2 < RelNum; ++Index2) {
if (((uint32_t)Rel->r_offset) == mBaseAddress + mImageInfo.RelocInfo.Relocs[Index2].Target) {
New = FALSE;
}
}
if (New) {
mImageInfo.RelocInfo.Relocs[RelNum].Type = EFI_IMAGE_REL_BASED_DIR64;
mImageInfo.RelocInfo.Relocs[RelNum].Target = (uint32_t)(Rel->r_offset - mBaseAddress);
++RelNum;
}
break;
case R_X86_64_32:
@ -404,19 +407,9 @@ SetRelocs (
break;
case R_AARCH64_ABS64:
case R_AARCH64_RELATIVE:
New = TRUE;
for (Index2 = 0; Index2 < RelNum; ++Index2) {
if (((uint32_t)Rel->r_offset) == mBaseAddress + mImageInfo.RelocInfo.Relocs[Index2].Target) {
New = FALSE;
}
}
if (New) {
mImageInfo.RelocInfo.Relocs[RelNum].Type = EFI_IMAGE_REL_BASED_DIR64;
mImageInfo.RelocInfo.Relocs[RelNum].Target = (uint32_t)(Rel->r_offset - mBaseAddress);
++RelNum;
}
break;
case R_AARCH64_ABS32:
@ -540,11 +533,16 @@ CreateIntermediate (
return RETURN_VOLUME_CORRUPTED;
}
if (!ProcessRelocSection (Shdr)) {
continue;
}
for (RIndex = 0; RIndex < Shdr->sh_size; RIndex += (UINTN)Shdr->sh_entsize) {
Rel = (Elf_Rel *)((UINT8 *)mEhdr + Shdr->sh_offset + RIndex);
#if defined(EFI_TARGET64)
if (mEhdr->e_machine == EM_X86_64) {
if ((ELF_R_TYPE(Rel->r_info) == R_X86_64_64)
if ((ELF_R_TYPE(Rel->r_info) == R_X86_64_RELATIVE)
|| (ELF_R_TYPE(Rel->r_info) == R_X86_64_64)
|| (ELF_R_TYPE(Rel->r_info) == R_X86_64_32)
|| (ELF_R_TYPE(Rel->r_info) == R_X86_64_GOTPCREL)
|| (ELF_R_TYPE(Rel->r_info) == R_X86_64_GOTPCRELX)