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[操作系统][PE结构分析] 10.基址重定位


源代码如下:

typedef struct _IMAGE_BASE_RELOCATION {  DWORD  VirtualAddress;  DWORD  SizeOfBlock;// WORD  TypeOffset[1];} IMAGE_BASE_RELOCATION;typedef IMAGE_BASE_RELOCATION UNALIGNED * PIMAGE_BASE_RELOCATION;

重定位表是一个数组,这个数组的大小记载在 _IMAGE_OPTIONAL_HEADER 的

.DataDirect‌​ory[IMAGE_DIRECTORY_E‌​NTRY_BASERELOC].Size 成员中

结构图如下,图片中 0 和 000 都表示16进制数,转换到二进制是  0000 和 0000 0000 0000:

zINMj

每个元素的大小都记载在 SizeOfBlock 中,这个元素是由 一个 _IMAGE_BASE_RELOCATION 结构体和一个TypeOffset 数组组成的。TypeOffset 数组的每个元素占2个字节,其中,高4位是偏移类型(type),低12位表示需要重定位的地址(Offset),即,它与 VirtualAddress 相加即是指向 PE 映像中需要修改的那个代码的RVA。

偏移类型的含义如下:

Constant

Value

Description

IMAGE_REL_BASED_ABSOLUTE

  0

The base relocation is skipped. This type can be used to pad a block.

IMAGE_REL_BASED_HIGH

  1

The base relocation adds the high 16 bits of the difference to the 16bit field at offset. The 16-bit field represents the high value of a 32-bit word.

IMAGE_REL_BASED_LOW

  2

The base relocation adds the low 16 bits of the difference to the 16-bit field at offset. The 16-bit field represents the low half of a 32-bit word.

IMAGE_REL_BASED_HIGHLOW

  3

The base relocation applies all 32 bits of the difference to the 32-bit field at offset.

IMAGE_REL_BASED_HIGHADJ

  4

The base relocation adds the high 16 bits of the difference to the 16-bit field at offset. The 16-bit field represents the high value of a 32-bit word. The low 16 bits of the 32-bit value are stored in the 16-bit word that follows this base relocation. This means that this base relocation occupies two slots.

IMAGE_REL_BASED_MIPS_JMPADDR

  5

The relocation interpretation is dependent on the machine type.

When the machine type is MIPS, the base relocation applies to a MIPS jump instruction.

IMAGE_REL_BASED_ARM_MOV32

  5

This relocation is meaningfull only when the machine type is ARM or Thumb. The base relocation applies the 32-bit address of a symbol across a consecutive MOVW/MOVT instruction pair.

IMAGE_REL_BASED_RISCV_HIGH20

  5

This relocation is only meaningful when the machine type is RISC-V. The base relocation applies to the high 20 bits of a 32-bit absolute address.

 

  6

Reserved, must be zero.

IMAGE_REL_BASED_THUMB_MOV32

  7

This relocation is meaningful only when the machine type is Thumb. The base relocation applies the 32-bit address of a symbol to a consecutive MOVW/MOVT instruction pair.

IMAGE_REL_BASED_RISCV_LOW12I

  7

This relocation is only meaningful when the machine type is RISC-V. The base relocation applies to the low 12 bits of a 32-bit absolute address formed in RISC-V I-type instruction format.

IMAGE_REL_BASED_RISCV_LOW12S

  8

This relocation is only meaningful when the machine type is RISC-V. The base relocation applies to the low 12 bits of a 32-bit absolute address formed in RISC-V S-type instruction format.

IMAGE_REL_BASED_MIPS_JMPADDR16

  9

The relocation is only meaningful when the machine type is MIPS. The base relocation applies to a MIPS16 jump instruction.

IMAGE_REL_BASED_DIR64

10

The base relocation applies the difference to the 64-bit field at offset.

其他中文翻译:

常量描述
IMAGE_REL_BASED_ABSOLUTE       0x0使块按照32位对齐,位置为0。
IMAGE_REL_BASED_HIGH0x1高16位必须应用于偏移量所指高字16位。
IMAGE_REL_BASED_LOW0x2低16位必须应用于偏移量所指低字16位。
IMAGE_REL_BASED_HIGHLOW0x3全部32位应用于所有32位。
IMAGE_REL_BASED_HIGHADJ0x4需要32位,高16位位于偏移量,低16位位于下一个偏移量数组元素,组合为一个带符号数,加上32位的一个数,然后加上8000然后把高16位保存在偏移量的16位域内。

例子:

分析常见的dll:在QQ中的 zlib.dll 文件 (在QQ安装目录下的bin文件夹中):

首先找到重定位表,这里使用工具:

001

找到数据:

002

VirtualAddress 为 0x1000,SizeOfBlock 为 0x64。第一个条目为 0x338C,高四位为 0x3,offset为 0x38C,即偏移地址为 0x138C (由 0x1000 + 0x38C得来)应用于此地址上全部32位。打开C32Asm反汇编查看:

003