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Add flag name translations for section and program headers
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@HarshKapadia2
HarshKapadia2 committed Sep 14, 2024
1 parent 43d1385 commit 22bdb00
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95 changes: 52 additions & 43 deletions README.md
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Original file line number Diff line number Diff line change
Expand Up @@ -94,171 +94,180 @@ ELF File Section Headers:
---------------------------------------------------------------------
[0]
NULL 0 0
0 0 0 0 0 0
0 0 0 0 0
---------------------------------------------------------------------
[1] .interp
PROGBITS 0x318 792
28 0 0x2 0 0 1
28 0 A 0 0 1
---------------------------------------------------------------------
[2] .note.gnu.property
NOTE 0x338 824
48 0 0x2 0 0 8
48 0 A 0 0 8
---------------------------------------------------------------------
[3] .note.gnu.build-id
NOTE 0x368 872
36 0 0x2 0 0 4
36 0 A 0 0 4
---------------------------------------------------------------------
[4] .note.ABI-tag
NOTE 0x38c 908
32 0 0x2 0 0 4
32 0 A 0 0 4
---------------------------------------------------------------------
[5] .gnu.hash
0x6ffffff6 0x3b0 944
240 0 0x2 6 0 8
240 0 A 6 0 8
---------------------------------------------------------------------
[6] .dynsym
DYNSYM 0x4a0 1184
8568 24 0x2 7 1 8
8568 24 A 7 1 8
---------------------------------------------------------------------
[7] .dynstr
STRTAB 0x2618 9752
4267 0 0x2 0 0 1
4267 0 A 0 0 1
---------------------------------------------------------------------
[8] .gnu.version
0x6fffffff 0x36c4 14020
714 2 0x2 6 0 2
714 2 A 6 0 2
---------------------------------------------------------------------
[9] .gnu.version_r
0x6ffffffe 0x3990 14736
320 0 0x2 7 5 8
320 0 A 7 5 8
---------------------------------------------------------------------
[10] .rela.dyn
RELA 0x3ad0 15056
202464 24 0x2 6 0 8
202464 24 A 6 0 8
---------------------------------------------------------------------
[11] .rela.plt
RELA 0x351b0 217520
7704 24 0x42 6 25 8
7704 24 IA 6 25 8
---------------------------------------------------------------------
[12] .init
PROGBITS 0x37000 225280
27 0 0x6 0 0 4
27 0 XA 0 0 4
---------------------------------------------------------------------
[13] .plt
PROGBITS 0x37020 225312
5152 16 0x6 0 0 16
5152 16 XA 0 0 16
---------------------------------------------------------------------
[14] .plt.got
PROGBITS 0x38440 230464
48 16 0x6 0 0 16
48 16 XA 0 0 16
---------------------------------------------------------------------
[15] .plt.sec
PROGBITS 0x38470 230512
5136 16 0x6 0 0 16
5136 16 XA 0 0 16
---------------------------------------------------------------------
[16] .text
PROGBITS 0x39880 235648
2845383 0 0x6 0 0 16
2845383 0 XA 0 0 16
---------------------------------------------------------------------
[17] .fini
PROGBITS 0x2f0348 3081032
13 0 0x6 0 0 4
13 0 XA 0 0 4
---------------------------------------------------------------------
[18] .rodata
PROGBITS 0x2f1000 3084288
166822 0 0x2 0 0 32
166822 0 A 0 0 32
---------------------------------------------------------------------
[19] .eh_frame_hdr
PROGBITS 0x319ba8 3251112
37684 0 0x2 0 0 4
37684 0 A 0 0 4
---------------------------------------------------------------------
[20] .eh_frame
PROGBITS 0x322ee0 3288800
265108 0 0x2 0 0 8
265108 0 A 0 0 8
---------------------------------------------------------------------
[21] .init_array
INIT_ARRAY 0x365230 3555888
8 8 0x3 0 0 8
8 8 AW 0 0 8
---------------------------------------------------------------------
[22] .fini_array
FINI_ARRAY 0x365238 3555896
8 8 0x3 0 0 8
8 8 AW 0 0 8
---------------------------------------------------------------------
[23] .data.rel.ro
PROGBITS 0x365240 3555904
65792 0 0x3 0 0 32
65792 0 AW 0 0 32
---------------------------------------------------------------------
[24] .dynamic
DYNAMIC 0x375340 3621696
608 16 0x3 7 0 8
608 16 AW 7 0 8
---------------------------------------------------------------------
[25] .got
PROGBITS 0x3755a0 3622304
2648 8 0x3 0 0 8
2648 8 AW 0 0 8
---------------------------------------------------------------------
[26] .data
PROGBITS 0x376000 3624960
160601 0 0x3 0 0 32
160601 0 AW 0 0 32
---------------------------------------------------------------------
[27] .bss
NOBITS 0x39d360 3785561
58176 0 0x3 0 0 32
58176 0 AW 0 0 32
---------------------------------------------------------------------
[28] .gnu_debuglink
PROGBITS 0 3785564
52 0 0 0 0 4
52 0 0 0 4
---------------------------------------------------------------------
[29] .shstrtab
STRTAB 0 3785616
285 0 0 0 0 1
285 0 0 0 1
---------------------------------------------------------------------

Section Header flag legend:
W (write), A (alloc), X (execute), M (merge), S (strings),
I (info), L (link order), O (extra OS processing required),
G (group), T (TLS), o (OS specific), P (processor specific),
R (ordered), E (exclude)


ELF File Segment (Program) Headers:

Type Offset VirtAddr PhysAddr
FileSiz MemSiz Flags Align
---------------------------------------------------------------------
PHDR 0x40 0x40 0x40
0x2d8 0x2d8 0x4 0x8
0x2d8 0x2d8 R 0x8
---------------------------------------------------------------------
INTERP 0x318 0x318 0x318
0x1c 0x1c 0x4 0x1
0x1c 0x1c R 0x1
---------------------------------------------------------------------
LOAD 0 0 0
0x36fc8 0x36fc8 0x4 0x1000
0x36fc8 0x36fc8 R 0x1000
---------------------------------------------------------------------
LOAD 0x37000 0x37000 0x37000
0x2b9355 0x2b9355 0x5 0x1000
0x2b9355 0x2b9355 RX 0x1000
---------------------------------------------------------------------
LOAD 0x2f1000 0x2f1000 0x2f1000
0x72a74 0x72a74 0x4 0x1000
0x72a74 0x72a74 R 0x1000
---------------------------------------------------------------------
LOAD 0x364230 0x365230 0x365230
0x38129 0x46470 0x6 0x1000
0x38129 0x46470 RW 0x1000
---------------------------------------------------------------------
DYNAMIC 0x374340 0x375340 0x375340
0x260 0x260 0x6 0x8
0x260 0x260 RW 0x8
---------------------------------------------------------------------
NOTE 0x338 0x338 0x338
0x30 0x30 0x4 0x8
0x30 0x30 R 0x8
---------------------------------------------------------------------
NOTE 0x368 0x368 0x368
0x44 0x44 0x4 0x4
0x44 0x44 R 0x4
---------------------------------------------------------------------
0x6474e553 0x338 0x338 0x338
0x30 0x30 0x4 0x8
0x30 0x30 R 0x8
---------------------------------------------------------------------
0x6474e550 0x319ba8 0x319ba8 0x319ba8
0x9334 0x9334 0x4 0x4
0x9334 0x9334 R 0x4
---------------------------------------------------------------------
0x6474e551 0 0 0
0 0 0x6 0x10
0 0 RW 0x10
---------------------------------------------------------------------
0x6474e552 0x364230 0x365230 0x365230
0x10dd0 0x10dd0 0x4 0x1
0x10dd0 0x10dd0 R 0x1
---------------------------------------------------------------------

Program (Segment) Header flag legend:
X (execute), W (write), R (read)


Dynamic dependencies listed in the ELF file:
-> libm.so.6
Expand Down
17 changes: 17 additions & 0 deletions include/pelf.h
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Original file line number Diff line number Diff line change
Expand Up @@ -9,8 +9,23 @@
#define MAGIC_BYTE_COUNT 4
#define SHN_UNDEF 0
#define SHN_XINDEX 0xffff
#define NUM_SEC_FLAGS 14
#define NUM_SEG_FLAGS 3
const char *ELF_MAGIC_BYTES = "\x7F"
"ELF";
const uint64_t SEC_FLAG_VAL[14] = {0x1, 0x2, 0x4, 0x10,
0x20, 0x40, 0x80, 0x100,
0x200, 0x400, 0x0FF00000, 0xF0000000,
0x4000000, 0x8000000}; // Maintain ascending
// order
const char *SEC_FLAG_STR[14] = {
"W", "A", "X", "M", "S", "I", "L",
"O", "G", "T", "o", "P", "R", "E"}; // Values correspond to the values in
// SEC_FLAG_VAL
const uint64_t SEG_FLAG_VAL[3] = {0x1, 0x2, 0x4}; // Maintain ascending
// order
const char *SEG_FLAG_STR[3] = {"X", "W", "R"}; // Values correspond to the
// values in SEG_FLAG_VAL

// Structure definitions
// 64-bit ELF (file) header
Expand Down Expand Up @@ -85,6 +100,8 @@ void print_elf64_phdrs(const elf64_phdr *prog_hdr_arr,
void get_magic_bytes(FILE *file, unsigned char *magic_bytes);
uint8_t get_elf_class(FILE *file);
bool is_magic_bytes_elf(const unsigned char *magic_bytes);
char *get_flag_str(uint64_t target_total, const uint64_t flag_val_arr[],
const char *flag_str_arr[], int num_flags);
char *get_sec_type_name(uint32_t sec_type);
char *get_seg_type_name(uint32_t p_type);

Expand Down
70 changes: 68 additions & 2 deletions src/pelf.c
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Original file line number Diff line number Diff line change
Expand Up @@ -381,6 +381,8 @@ void print_elf64_shdrs(const elf64_shdr *sec_hdr_arr, uint16_t num_sec,
for (int i = 0; i < num_sec; i++) {
const elf64_shdr sec_hdr = sec_hdr_arr[i];
char *sec_type_name = get_sec_type_name(sec_hdr.sh_type);
char *sec_flag_str = get_flag_str(sec_hdr.sh_flags, SEC_FLAG_VAL,
SEC_FLAG_STR, NUM_SEC_FLAGS);

printf("[%d]\t", i);
printf("%s", (shstrtab + sec_hdr.sh_name));
Expand All @@ -392,22 +394,37 @@ void print_elf64_shdrs(const elf64_shdr *sec_hdr_arr, uint16_t num_sec,
} else {
printf("%s\t\t", sec_type_name);
}

printf("%#lx\t\t", sec_hdr.sh_addr);
printf("%lu", sec_hdr.sh_offset);

printf("\n\t");

printf("%lu\t\t", sec_hdr.sh_size);
printf("%lu\t\t", sec_hdr.sh_entsize);
printf("%#lx ", sec_hdr.sh_flags);

if (sec_flag_str == NULL) {
printf("%#lx ", sec_hdr.sh_flags);
} else {
printf("%s ", sec_flag_str);
}

printf("%d \t", sec_hdr.sh_link);
printf("%d ", sec_hdr.sh_info);
printf("%lu", sec_hdr.sh_addralign);

printf("\n---------------------------------------------------------"
"------------\n");

free(sec_flag_str);
}

printf("\nSection Header flag legend:\n"
"W (write), A (alloc), X (execute), M (merge), S (strings),\n"
"I (info), L (link order), O (extra OS processing required),\n"
"G (group), T (TLS), o (OS specific), P (processor specific),\n"
"R (ordered), E (exclude)\n");

printf("\n\n");
}

Expand All @@ -429,12 +446,15 @@ void print_elf64_phdrs(const elf64_phdr *prog_hdr_arr,
for (int i = 0; i < file_hdr->e_phnum; i++) {
const elf64_phdr prog_hdr = prog_hdr_arr[i];
char *seg_type_name = get_seg_type_name(prog_hdr.p_type);
char *seg_flag_str = get_flag_str(prog_hdr.p_flags, SEG_FLAG_VAL,
SEG_FLAG_STR, NUM_SEG_FLAGS);

if (seg_type_name == NULL) {
printf("%#x\t\t", prog_hdr.p_type);
} else {
printf("%s\t\t", seg_type_name);
}

printf("%#lx\t\t", prog_hdr.p_offset);
printf("%#lx\t\t", prog_hdr.p_vaddr);
printf("%#lx", prog_hdr.p_paddr);
Expand All @@ -443,16 +463,62 @@ void print_elf64_phdrs(const elf64_phdr *prog_hdr_arr,

printf("%#lx\t\t", prog_hdr.p_filesz);
printf("%#lx\t\t", prog_hdr.p_memsz);
printf("%#x ", prog_hdr.p_flags);

if (seg_flag_str == NULL) {
printf("%#x ", prog_hdr.p_flags);
} else {
printf("%s ", seg_flag_str);
}

printf("%#lx", prog_hdr.p_align);

printf("\n---------------------------------------------------------"
"------------\n");

free(seg_flag_str);
}

printf("\nProgram (Segment) Header flag legend:\n"
"X (execute), W (write), R (read) \n");

printf("\n\n");
}

// Get flag combination string
char *get_flag_str(uint64_t target_total, const uint64_t flag_val_arr[],
const char *flag_str_arr[], int num_flags) {
char *flag_str = (char *)malloc(20 * sizeof(char));
char *flag_str_ptr = flag_str;

if (flag_str == NULL) {
return NULL;
}

for (int i = num_flags - 1; i >= 0; i--) {
const uint64_t flag_val = flag_val_arr[i];

if (flag_val <= target_total) {
*flag_str_ptr = *flag_str_arr[i];
flag_str_ptr++;

target_total = target_total - flag_val;

if (target_total == 0) {
break;
}
}
}

if (target_total == 0) {
*flag_str_ptr = '\0';

return flag_str;
} else {
free(flag_str);
return NULL;
}
}

// Get the name of the section type from its numeric representation
char *get_sec_type_name(uint32_t sec_type) {
switch (sec_type) {
Expand Down

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