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DriverLoader: Simplify PerformBaseRelocation(()

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This commit is contained in:
Nodir Temirkhodjaev 2021-12-13 15:06:09 +03:00
parent 621e442858
commit a2d0974177
1 changed files with 35 additions and 29 deletions
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64
src/driver/loader/fortmm.c
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@ -121,6 +121,40 @@ static NTSTATUS CopySectionTable(
return STATUS_SUCCESS;
}
static void PatchAddressRelocations(
PUCHAR codeBase, PIMAGE_BASE_RELOCATION relocation, ptrdiff_t locationDelta)
{
const PUCHAR dest = codeBase + relocation->VirtualAddress;
PUSHORT relInfo = (PUSHORT) ((PUCHAR) relocation + sizeof(IMAGE_BASE_RELOCATION));
const DWORD relInfoCount = (relocation->SizeOfBlock - sizeof(IMAGE_BASE_RELOCATION)) / 2;
for (DWORD i = 0; i < relInfoCount; ++i, ++relInfo) {
const INT type = *relInfo >> 12; /* the upper 4 bits define the type of relocation */
const INT offset = *relInfo & 0xfff; /* the lower 12 bits define the offset */
switch (type) {
case IMAGE_REL_BASED_ABSOLUTE:
break; /* skip relocation */
case IMAGE_REL_BASED_HIGHLOW:
/* change complete 32 bit address */
DWORD *patchAddrHL = (PDWORD) (dest + offset);
*patchAddrHL += (DWORD) locationDelta;
break;
#ifdef _WIN64
case IMAGE_REL_BASED_DIR64:
ULONGLONG *patchAddr64 = (PULONGLONG) (dest + offset);
*patchAddr64 += (ULONGLONG) locationDelta;
break;
#endif
default:
break;
}
}
}
/*
* The DLL's preferred load address conflicts with memory that's already in use
* so we need to 'rebase' the DLL by loading it at a different address that does
@ -142,35 +176,7 @@ static NTSTATUS PerformBaseRelocation(
(PIMAGE_BASE_RELOCATION) (codeBase + directory->VirtualAddress);
while (relocation->VirtualAddress > 0) {
const PUCHAR dest = codeBase + relocation->VirtualAddress;
PUSHORT relInfo = (PUSHORT) ((PUCHAR) relocation + sizeof(IMAGE_BASE_RELOCATION));
const DWORD relInfoCount = (relocation->SizeOfBlock - sizeof(IMAGE_BASE_RELOCATION)) / 2;
for (DWORD i = 0; i < relInfoCount; ++i, ++relInfo) {
const INT type = *relInfo >> 12; /* the upper 4 bits define the type of relocation */
const INT offset = *relInfo & 0xfff; /* the lower 12 bits define the offset */
switch (type) {
case IMAGE_REL_BASED_ABSOLUTE:
break; /* skip relocation */
case IMAGE_REL_BASED_HIGHLOW:
/* change complete 32 bit address */
DWORD *patchAddrHL = (PDWORD) (dest + offset);
*patchAddrHL += (DWORD) locationDelta;
break;
#ifdef _WIN64
case IMAGE_REL_BASED_DIR64:
ULONGLONG *patchAddr64 = (PULONGLONG) (dest + offset);
*patchAddr64 += (ULONGLONG) locationDelta;
break;
#endif
default:
break;
}
}
PatchAddressRelocations(codeBase, relocation, locationDelta);
/* Advance to next relocation block */
relocation = (PIMAGE_BASE_RELOCATION) ((PCHAR) relocation + relocation->SizeOfBlock);