手拆ELF32（一，文件头）

柔情只为你懂 2022-12-14 06:09 164阅读 0赞

# ELF详细指南 #

持续更新中…

拆解的文件放在百度云盘

[百度云盘提取文件][Link 1]

# elf.h中的宏定义 #

下列数据类型使用N比特架构 (N=32,64, ElfN 代表 Elf32 或 Elf64, uintN\_t 代表 uint32\_t or uint64\_t):

ElfN_Addr       Unsigned program address, uintN_t
    ElfN_Off        Unsigned file offset, uintN_t
    ElfN_Section    Unsigned section index, uint16_t
    ElfN_Versym     Unsigned version symbol information, uint16_t
    Elf_Byte        unsigned char
    ElfN_Half       uint16_t
    ElfN_Sword      int32_t
    ElfN_Word       uint32_t
    ElfN_Sxword     int64_t
    ElfN_Xword      uint64_t

且elf.h中的结构体是以4字节对齐

# EFL32 #

拆解的文件是：elf32（可以从百度云盘下载）

## ELF头（Elf32\_Ehdr） ##

ELF32文件头定义为Elf32\_Ehdr，大小为52字节

#define EI_NIDENT (16)
    
    typedef struct
    { 
      unsigned char	e_ident[EI_NIDENT];	/* Magic number and other info */
      Elf32_Half	e_type;			/* Object file type */
      Elf32_Half	e_machine;		/* Architecture */
      Elf32_Word	e_version;		/* Object file version */
      Elf32_Addr	e_entry;		/* Entry point virtual address */
      Elf32_Off		e_phoff;		/* Program header table file offset */
      Elf32_Off		e_shoff;		/* Section header table file offset */
      Elf32_Word	e_flags;		/* Processor-specific flags */
      Elf32_Half	e_ehsize;		/* ELF header size in bytes */
      Elf32_Half	e_phentsize;		/* Program header table entry size */
      Elf32_Half	e_phnum;		/* Program header table entry count */
      Elf32_Half	e_shentsize;		/* Section header table entry size */
      Elf32_Half	e_shnum;		/* Section header table entry count */
      Elf32_Half	e_shstrndx;		/* Section header string table index */
    } Elf32_Ehdr;

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzM2OTYzMjE0_size_16_color_FFFFFF_t_70_pic_center]

7F 45 4C 46 01 01 01 00 00 00 00 00 00 00 00 00 
    03 00 03 00 01 00 00 00 C0 06 00 00 34 00 00 00 
    A8 19 00 00 00 00 00 00 34 00 20 00 09 00 28 00 
    1D 00 1C 00

使用readelf工具查看elf32文件头如下

young@ubuntu:~/c/elf$ readelf -h elf32
    ELF Header:
      Magic:   7f 45 4c 46 01 01 01 00 00 00 00 00 00 00 00 00 
      Class:                             ELF32
      Data:                              2's complement, little endian
      Version:                           1 (current)
      OS/ABI:                            UNIX - System V
      ABI Version:                       0
      Type:                              DYN (Shared object file)
      Machine:                           Intel 80386
      Version:                           0x1
      Entry point address:               0x6c0
      Start of program headers:          52 (bytes into file)
      Start of section headers:          6568 (bytes into file)
      Flags:                             0x0
      Size of this header:               52 (bytes)
      Size of program headers:           32 (bytes)
      Number of program headers:         9
      Size of section headers:           40 (bytes)
      Number of section headers:         29
      Section header string table index: 28

### e\_ident ###

该成员是大小为16字节的数组，存放ELF的魔数及其它信息  
如截图所示，e\_ident的值为：  
`7F 45 4C 46 01 01 01 00 00 00 00 00 00 00 00 00`

*  EI\_MAG  
    前四字节为ELFMAG，值为`"\x7fELF`，用于判断一个文件是否是ELF文件.  
    EI\_MAG0、EI\_MAG1、EI\_MAG2、EI\_MAG3为e\_ident的数组下标  
    ELFMAG0、ELFMAG1、ELFMAG2、ELFMAG3为对应的值。

#define EI_MAG0 0 /* File identification byte 0 index */
    #define ELFMAG0 0x7f /* Magic number byte 0 */
    
    #define EI_MAG1 1 /* File identification byte 1 index */
    #define ELFMAG1 'E' /* Magic number byte 1 */
    
    #define EI_MAG2 2 /* File identification byte 2 index */
    #define ELFMAG2 'L' /* Magic number byte 2 */
    
    #define EI_MAG3 3 /* File identification byte 3 index */
    #define ELFMAG3 'F' /* Magic number byte 3 */
    
    /* Conglomeration of the identification bytes, for easy testing as a word. */
    #define ELFMAG "\177ELF"

*  EI\_CLASS  
    第五个字节为EI\_CLASS，即e\_ident\[EI\_CLASS\]，它有四个值。截图中e\_ident\[EI\_CLASS\] = 01，表示文件为32 bits的ELF对象

#define EI_CLASS 4 /* File class byte index */
    #define ELFCLASSNONE 0 /* Invalid class */
    #define ELFCLASS32 1 /* 32-bit objects */
    #define ELFCLASS64 2 /* 64-bit objects */
    #define ELFCLASSNUM 3

*  EI\_DATA  
    第六个字节为EI\_DATA，即e\_ident\[EI\_DATA\]，它有四个值，用来表示文件是大端还是小端的，截图中e\_ident\[EI\_DATA\] = 01，表示文件数据是以小端方式存储的。

#define EI_DATA 5 /* Data encoding byte index */
    #define ELFDATANONE 0 /* Invalid data encoding */
    #define ELFDATA2LSB 1 /* 2's complement, little endian */
    #define ELFDATA2MSB 2 /* 2's complement, big endian */
    #define ELFDATANUM 3

*  EI\_VERSION  
    第七个字节为EI\_VERSION，即e\_ident\[EI\_VERSION\]，它的值必须为EV\_CURRENT，EV\_CURRENT被宏定义为1

#define EI_VERSION 6 /* File version byte index */
    					        /* Value must be EV_CURRENT */

/* Legal values for e_version (version). */
    
    #define EV_NONE 0 /* Invalid ELF version */
    #define EV_CURRENT 1 /* Current version */
    #define EV_NUM 2

*  EI\_OSABI  
    第八个字节为EI\_OSABI，即e\_ident\[EI\_OSABI\]，用来标识ELF文件的系统类型，截图中e\_ident\[EI\_OSABI\] = 0，表示ELF文件可以在UNIX系统上运行  
    `tips: ABI(application binary interface)`

#define EI_OSABI 7 /* OS ABI identification */
    #define ELFOSABI_NONE 0 /* UNIX System V ABI */
    #define ELFOSABI_SYSV 0 /* Alias. */
    #define ELFOSABI_HPUX 1 /* HP-UX */
    #define ELFOSABI_NETBSD 2 /* NetBSD. */
    #define ELFOSABI_GNU 3 /* Object uses GNU ELF extensions. */
    #define ELFOSABI_LINUX ELFOSABI_GNU /* Compatibility alias. */
    #define ELFOSABI_SOLARIS 6 /* Sun Solaris. */
    #define ELFOSABI_AIX 7 /* IBM AIX. */
    #define ELFOSABI_IRIX 8 /* SGI Irix. */
    #define ELFOSABI_FREEBSD 9 /* FreeBSD. */
    #define ELFOSABI_TRU64 10 /* Compaq TRU64 UNIX. */
    #define ELFOSABI_MODESTO 11 /* Novell Modesto. */
    #define ELFOSABI_OPENBSD 12 /* OpenBSD. */
    #define ELFOSABI_ARM_AEABI 64 /* ARM EABI */
    #define ELFOSABI_ARM 97 /* ARM */
    #define ELFOSABI_STANDALONE 255 /* Standalone (embedded) application */

*  EI\_ABIVERSION  
    第九个字节为EI\_ABIVERSION，表示ABI版本，

#define EI_ABIVERSION 8 /* ABI version */

*  EI\_PAD  
    第十位及之后的填充0，为了对齐。

#define EI_PAD 9 /* Byte index of padding bytes */

### e\_type ###

该成员标识ELF文件的类型，有如下类型：

*  ET\_NONE：未知文件
 *  ET\_REL：重定位表文件
 *  ET\_EXEC：可执行文件
 *  ET\_DYN：共享目标文件
 *  ET\_CORE：核心文件  
    截图中e\_type为0x0003，表示文件为共享对象文件，但它实际是一个可以执行的文件  
    **注：GCC使用编译选项 -pie 编译的可执行文件实际 也是DT\_DYN类型。**

/* Legal values for e_type (object file type). */
    
    #define ET_NONE 0 /* No file type */
    #define ET_REL 1 /* Relocatable file */
    #define ET_EXEC 2 /* Executable file */
    #define ET_DYN 3 /* Shared object file */
    #define ET_CORE 4 /* Core file */
    #define ET_NUM 5 /* Number of defined types */
    #define ET_LOOS 0xfe00 /* OS-specific range start */
    #define ET_HIOS 0xfeff /* OS-specific range end */
    #define ET_LOPROC 0xff00 /* Processor-specific range start */
    #define ET_HIPROC 0xffff /* Processor-specific range end */

### e\_machine ###

表示执行ELF的架构，截图中e\_machine为0x0003，表示CPU为Intel 80386架构

/* Legal values for e_machine (architecture). */
    
    #define EM_NONE 0 /* No machine */
    #define EM_M32 1 /* AT&T WE 32100 */
    #define EM_SPARC 2 /* SUN SPARC */
    #define EM_386 3 /* Intel 80386 */
    #define EM_68K 4 /* Motorola m68k family */
    #define EM_88K 5 /* Motorola m88k family */
    #define EM_IAMCU 6 /* Intel MCU */
    #define EM_860 7 /* Intel 80860 */
    #define EM_MIPS 8 /* MIPS R3000 big-endian */
    #define EM_S370 9 /* IBM System/370 */
    #define EM_MIPS_RS3_LE 10 /* MIPS R3000 little-endian */
    				/* reserved 11-14 */
    #define EM_PARISC 15 /* HPPA */
    				/* reserved 16 */
    #define EM_VPP500 17 /* Fujitsu VPP500 */
    #define EM_SPARC32PLUS 18 /* Sun's "v8plus" */
    #define EM_960 19 /* Intel 80960 */
    #define EM_PPC 20 /* PowerPC */
    #define EM_PPC64 21 /* PowerPC 64-bit */
    #define EM_S390 22 /* IBM S390 */
    #define EM_SPU 23 /* IBM SPU/SPC */
    				/* reserved 24-35 */
    #define EM_V800 36 /* NEC V800 series */
    #define EM_FR20 37 /* Fujitsu FR20 */
    #define EM_RH32 38 /* TRW RH-32 */
    #define EM_RCE 39 /* Motorola RCE */
    #define EM_ARM 40 /* ARM */
    #define EM_FAKE_ALPHA 41 /* Digital Alpha */
    #define EM_SH 42 /* Hitachi SH */
    #define EM_SPARCV9 43 /* SPARC v9 64-bit */
    #define EM_TRICORE 44 /* Siemens Tricore */
    #define EM_ARC 45 /* Argonaut RISC Core */
    #define EM_H8_300 46 /* Hitachi H8/300 */
    #define EM_H8_300H 47 /* Hitachi H8/300H */
    #define EM_H8S 48 /* Hitachi H8S */
    #define EM_H8_500 49 /* Hitachi H8/500 */
    #define EM_IA_64 50 /* Intel Merced */
    #define EM_MIPS_X 51 /* Stanford MIPS-X */
    #define EM_COLDFIRE 52 /* Motorola Coldfire */
    #define EM_68HC12 53 /* Motorola M68HC12 */
    #define EM_MMA 54 /* Fujitsu MMA Multimedia Accelerator */
    #define EM_PCP 55 /* Siemens PCP */
    #define EM_NCPU 56 /* Sony nCPU embeeded RISC */
    #define EM_NDR1 57 /* Denso NDR1 microprocessor */
    #define EM_STARCORE 58 /* Motorola Start*Core processor */
    #define EM_ME16 59 /* Toyota ME16 processor */
    #define EM_ST100 60 /* STMicroelectronic ST100 processor */
    #define EM_TINYJ 61 /* Advanced Logic Corp. Tinyj emb.fam */
    #define EM_X86_64 62 /* AMD x86-64 architecture */
    #define EM_PDSP 63 /* Sony DSP Processor */
    #define EM_PDP10 64 /* Digital PDP-10 */
    #define EM_PDP11 65 /* Digital PDP-11 */
    #define EM_FX66 66 /* Siemens FX66 microcontroller */
    #define EM_ST9PLUS 67 /* STMicroelectronics ST9+ 8/16 mc */
    #define EM_ST7 68 /* STmicroelectronics ST7 8 bit mc */
    #define EM_68HC16 69 /* Motorola MC68HC16 microcontroller */
    #define EM_68HC11 70 /* Motorola MC68HC11 microcontroller */
    #define EM_68HC08 71 /* Motorola MC68HC08 microcontroller */
    #define EM_68HC05 72 /* Motorola MC68HC05 microcontroller */
    #define EM_SVX 73 /* Silicon Graphics SVx */
    #define EM_ST19 74 /* STMicroelectronics ST19 8 bit mc */
    #define EM_VAX 75 /* Digital VAX */
    #define EM_CRIS 76 /* Axis Communications 32-bit emb.proc */
    #define EM_JAVELIN 77 /* Infineon Technologies 32-bit emb.proc */
    #define EM_FIREPATH 78 /* Element 14 64-bit DSP Processor */
    #define EM_ZSP 79 /* LSI Logic 16-bit DSP Processor */
    #define EM_MMIX 80 /* Donald Knuth's educational 64-bit proc */
    #define EM_HUANY 81 /* Harvard University machine-independent object files */
    #define EM_PRISM 82 /* SiTera Prism */
    #define EM_AVR 83 /* Atmel AVR 8-bit microcontroller */
    #define EM_FR30 84 /* Fujitsu FR30 */
    #define EM_D10V 85 /* Mitsubishi D10V */
    #define EM_D30V 86 /* Mitsubishi D30V */
    #define EM_V850 87 /* NEC v850 */
    #define EM_M32R 88 /* Mitsubishi M32R */
    #define EM_MN10300 89 /* Matsushita MN10300 */
    #define EM_MN10200 90 /* Matsushita MN10200 */
    #define EM_PJ 91 /* picoJava */
    #define EM_OPENRISC 92 /* OpenRISC 32-bit embedded processor */
    #define EM_ARC_COMPACT 93 /* ARC International ARCompact */
    #define EM_XTENSA 94 /* Tensilica Xtensa Architecture */
    #define EM_VIDEOCORE 95 /* Alphamosaic VideoCore */
    #define EM_TMM_GPP 96 /* Thompson Multimedia General Purpose Proc */
    #define EM_NS32K 97 /* National Semi. 32000 */
    #define EM_TPC 98 /* Tenor Network TPC */
    #define EM_SNP1K 99 /* Trebia SNP 1000 */
    #define EM_ST200 100 /* STMicroelectronics ST200 */
    #define EM_IP2K 101 /* Ubicom IP2xxx */
    #define EM_MAX 102 /* MAX processor */
    #define EM_CR 103 /* National Semi. CompactRISC */
    #define EM_F2MC16 104 /* Fujitsu F2MC16 */
    #define EM_MSP430 105 /* Texas Instruments msp430 */
    #define EM_BLACKFIN 106 /* Analog Devices Blackfin DSP */
    #define EM_SE_C33 107 /* Seiko Epson S1C33 family */
    #define EM_SEP 108 /* Sharp embedded microprocessor */
    #define EM_ARCA 109 /* Arca RISC */
    #define EM_UNICORE 110 /* PKU-Unity & MPRC Peking Uni. mc series */
    #define EM_EXCESS 111 /* eXcess configurable cpu */
    #define EM_DXP 112 /* Icera Semi. Deep Execution Processor */
    #define EM_ALTERA_NIOS2 113 /* Altera Nios II */
    #define EM_CRX 114 /* National Semi. CompactRISC CRX */
    #define EM_XGATE 115 /* Motorola XGATE */
    #define EM_C166 116 /* Infineon C16x/XC16x */
    #define EM_M16C 117 /* Renesas M16C */
    #define EM_DSPIC30F 118 /* Microchip Technology dsPIC30F */
    #define EM_CE 119 /* Freescale Communication Engine RISC */
    #define EM_M32C 120 /* Renesas M32C */
    				/* reserved 121-130 */
    #define EM_TSK3000 131 /* Altium TSK3000 */
    #define EM_RS08 132 /* Freescale RS08 */
    #define EM_SHARC 133 /* Analog Devices SHARC family */
    #define EM_ECOG2 134 /* Cyan Technology eCOG2 */
    #define EM_SCORE7 135 /* Sunplus S+core7 RISC */
    #define EM_DSP24 136 /* New Japan Radio (NJR) 24-bit DSP */
    #define EM_VIDEOCORE3 137 /* Broadcom VideoCore III */
    #define EM_LATTICEMICO32 138 /* RISC for Lattice FPGA */
    #define EM_SE_C17 139 /* Seiko Epson C17 */
    #define EM_TI_C6000 140 /* Texas Instruments TMS320C6000 DSP */
    #define EM_TI_C2000 141 /* Texas Instruments TMS320C2000 DSP */
    #define EM_TI_C5500 142 /* Texas Instruments TMS320C55x DSP */
    #define EM_TI_ARP32 143 /* Texas Instruments App. Specific RISC */
    #define EM_TI_PRU 144 /* Texas Instruments Prog. Realtime Unit */
    				/* reserved 145-159 */
    #define EM_MMDSP_PLUS 160 /* STMicroelectronics 64bit VLIW DSP */
    #define EM_CYPRESS_M8C 161 /* Cypress M8C */
    #define EM_R32C 162 /* Renesas R32C */
    #define EM_TRIMEDIA 163 /* NXP Semi. TriMedia */
    #define EM_QDSP6 164 /* QUALCOMM DSP6 */
    #define EM_8051 165 /* Intel 8051 and variants */
    #define EM_STXP7X 166 /* STMicroelectronics STxP7x */
    #define EM_NDS32 167 /* Andes Tech. compact code emb. RISC */
    #define EM_ECOG1X 168 /* Cyan Technology eCOG1X */
    #define EM_MAXQ30 169 /* Dallas Semi. MAXQ30 mc */
    #define EM_XIMO16 170 /* New Japan Radio (NJR) 16-bit DSP */
    #define EM_MANIK 171 /* M2000 Reconfigurable RISC */
    #define EM_CRAYNV2 172 /* Cray NV2 vector architecture */
    #define EM_RX 173 /* Renesas RX */
    #define EM_METAG 174 /* Imagination Tech. META */
    #define EM_MCST_ELBRUS 175 /* MCST Elbrus */
    #define EM_ECOG16 176 /* Cyan Technology eCOG16 */
    #define EM_CR16 177 /* National Semi. CompactRISC CR16 */
    #define EM_ETPU 178 /* Freescale Extended Time Processing Unit */
    #define EM_SLE9X 179 /* Infineon Tech. SLE9X */
    #define EM_L10M 180 /* Intel L10M */
    #define EM_K10M 181 /* Intel K10M */
    				/* reserved 182 */
    #define EM_AARCH64 183 /* ARM AARCH64 */
    				/* reserved 184 */
    #define EM_AVR32 185 /* Amtel 32-bit microprocessor */
    #define EM_STM8 186 /* STMicroelectronics STM8 */
    #define EM_TILE64 187 /* Tileta TILE64 */
    #define EM_TILEPRO 188 /* Tilera TILEPro */
    #define EM_MICROBLAZE 189 /* Xilinx MicroBlaze */
    #define EM_CUDA 190 /* NVIDIA CUDA */
    #define EM_TILEGX 191 /* Tilera TILE-Gx */
    #define EM_CLOUDSHIELD 192 /* CloudShield */
    #define EM_COREA_1ST 193 /* KIPO-KAIST Core-A 1st gen. */
    #define EM_COREA_2ND 194 /* KIPO-KAIST Core-A 2nd gen. */
    #define EM_ARC_COMPACT2 195 /* Synopsys ARCompact V2 */
    #define EM_OPEN8 196 /* Open8 RISC */
    #define EM_RL78 197 /* Renesas RL78 */
    #define EM_VIDEOCORE5 198 /* Broadcom VideoCore V */
    #define EM_78KOR 199 /* Renesas 78KOR */
    #define EM_56800EX 200 /* Freescale 56800EX DSC */
    #define EM_BA1 201 /* Beyond BA1 */
    #define EM_BA2 202 /* Beyond BA2 */
    #define EM_XCORE 203 /* XMOS xCORE */
    #define EM_MCHP_PIC 204 /* Microchip 8-bit PIC(r) */
    				/* reserved 205-209 */
    #define EM_KM32 210 /* KM211 KM32 */
    #define EM_KMX32 211 /* KM211 KMX32 */
    #define EM_EMX16 212 /* KM211 KMX16 */
    #define EM_EMX8 213 /* KM211 KMX8 */
    #define EM_KVARC 214 /* KM211 KVARC */
    #define EM_CDP 215 /* Paneve CDP */
    #define EM_COGE 216 /* Cognitive Smart Memory Processor */
    #define EM_COOL 217 /* Bluechip CoolEngine */
    #define EM_NORC 218 /* Nanoradio Optimized RISC */
    #define EM_CSR_KALIMBA 219 /* CSR Kalimba */
    #define EM_Z80 220 /* Zilog Z80 */
    #define EM_VISIUM 221 /* Controls and Data Services VISIUMcore */
    #define EM_FT32 222 /* FTDI Chip FT32 */
    #define EM_MOXIE 223 /* Moxie processor */
    #define EM_AMDGPU 224 /* AMD GPU */
    				/* reserved 225-242 */
    #define EM_RISCV 243 /* RISC-V */
    
    #define EM_BPF 247 /* Linux BPF -- in-kernel virtual machine */
    
    #define EM_NUM 248
    
    /* Old spellings/synonyms. */
    
    #define EM_ARC_A5 EM_ARC_COMPACT
    
    /* If it is necessary to assign new unofficial EM_* values, please pick large random numbers (0x8523, 0xa7f2, etc.) to minimize the chances of collision with official or non-GNU unofficial values. */
    
    #define EM_ALPHA 0x9026

### e\_version ###

标识文件版本，截图中，文件版本为0x00000001

### e\_entry ###

这是比较重要的一个成员，这个成员标识了ELF的程序入口地址，它是一个虚拟机地址，表示在文件中的偏移。截图中，e\_entry为0x000006c0，在文件中0x6c0的内容如下：  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzM2OTYzMjE0_size_16_color_FFFFFF_t_70_pic_center 1]  
反汇编其中的内容如下：  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzM2OTYzMjE0_size_16_color_FFFFFF_t_70_pic_center 2]

### e\_phoff ###

该成员记录程序头表文件偏移。

截图中的程序头表为：0x00000034（十进制52）

### e\_shoff ###

该成员记录节区头表文件偏移。有的人喜欢将.text称为text节，有的人习惯叫text段或代码段。  
按照翻译，section应该翻译为节区，扇区。所以我这里统一称为节区

0x000019a8（十进制6568）

### e\_flags ###

处理器指定的与文件相关联的flag

截图中e\_flag的值为：0x00000000

### e\_ehsize ###

ELF文件头大小，这里是32位的ELF文件，其文件头Eld32\_Hdr大小为0x34(52)字节

### e\_phentsize ###

程序头表条目大小，用结构体Elf32\_Phdr表示。如果ELF文件没有程序头表，该成员的值为0。

截图中为e\_phentsize为：0x0020(32)，即结构体Elf32\_Phdr的大小为32字节

### e\_phnum ###

程序头表条目数量

截图中e\_phnum为：0x0009

e\_phnnum的特殊值

/* Special value for e_phnum. This indicates that the real number of program headers is too large to fit into e_phnum. Instead the real value is in the field sh_info of section 0. */
    
    #define PN_XNUM 0xffff

### e\_shentsize ###

节区头表条目大小  
截图中e\_shentsize为：0x0028

### e\_shnum ###

节区头表条目数量

截图中e\_shnum为：0x001d

### e\_shstrndx ###

节区头字符表索引  
截图中e\_shstrndx为：0x001c

e\_shstrndx的特殊值：

/* Special section indices. */
    
    #define SHN_UNDEF 0 /* Undefined section */
    #define SHN_LORESERVE 0xff00 /* Start of reserved indices */
    #define SHN_LOPROC 0xff00 /* Start of processor-specific */
    #define SHN_BEFORE 0xff00 /* Order section before all others (Solaris). */
    #define SHN_AFTER 0xff01 /* Order section after all others (Solaris). */
    #define SHN_HIPROC 0xff1f /* End of processor-specific */
    #define SHN_LOOS 0xff20 /* Start of OS-specific */
    #define SHN_HIOS 0xff3f /* End of OS-specific */
    #define SHN_ABS 0xfff1 /* Associated symbol is absolute */
    #define SHN_COMMON 0xfff2 /* Associated symbol is common */
    #define SHN_XINDEX 0xffff /* Index is in extra table. */
    #define SHN_HIRESERVE 0xffff /* End of reserved indices */

## 参考 ##

[elf.h头文件][elf.h]  
[elf man page][]

[Link 1]: https://pan.baidu.com/s/1HQVVX-Fh6ciQk0se-UfiAg
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzM2OTYzMjE0_size_16_color_FFFFFF_t_70_pic_center]: /images/20221123/437d4938ccf241b7a309a833e5d91cd0.png
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[elf.h]: https://github.com/lattera/glibc/blob/master/elf/elf.h
[elf man page]: https://man7.org/linux/man-pages/man5/elf.5.html