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main.c
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main.c
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/*
* user@asm:~/print-linux-elf64(1:477)$ uname -a
* Linux asm 5.10.0-13-amd64 #1 SMP Debian 5.10.106-1 (2022-03-17) x86_64 GNU/Linux
*
gcc -ggdb -O0 -o exe src.c && ./exe
clear; gcc -E src.c > src.pc; gcc -ggdb -O0 -c src.c && gcc -o exe src.o && ./exe
clear; gcc -E src.c > src.pc; gcc -Wformat -Wformat-signedness -ggdb -O0 -c src.c && gcc -o exe src.o && ./exe
*/
#define _GNU_SOURCE
//#define TFILE
//#define TMEM
//#define ONLY_NONAME
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <assert.h>
#include <unistd.h>
#include <fcntl.h>
#include <alloca.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <dirent.h>
#ifdef TFILE
#include <sys/mman.h>
#else
#ifndef TMEM
#define TMEM
#endif
#endif
#include <link.h>
#include <elf.h>
#include <sys/auxv.h>
#define MIN(a, b) ((a) < (b) ? (a) : (b))
extern const void* _start;
extern void* __libc_stack_end;
extern void dll_main();
//extern void* __bss_start;
//extern void* __bss_end;
// https://linuxjm.osdn.jp/html/LDP_man-pages/man3/end.3.html
extern char etext, edata, end;
typedef unsigned char byte_t;
#ifdef TMEM
static int phdr_callback(struct dl_phdr_info *info, size_t size, void *data);
static int phdr_foreach(int callback(struct dl_phdr_info *, size_t, void *));
#endif
__attribute__ ((constructor)) static void construct1()
{
puts("construct1");
}
__attribute__ ((constructor)) static void construct2()
{
puts("construct2");
}
__attribute__ ((destructor)) static void destruct1()
{
puts("destruct1");
}
__attribute__ ((destructor)) static void destruct2()
{
puts("destruct2");
}
static const char* auxv_type2str(uint64_t a_type);
static uint32_t new_hash_elf(const char* name);
static void print_phdrs(const ElfW(Phdr)* phdrs, const int nphdrs, const byte_t* baseadr);
static void print_phdr_members(const char* indent, const ElfW(Phdr)* elf_phdr);
static void print_dyns(const char* indent, const ElfW(Dyn)* dyns, const byte_t* baseadr);
static void print_syms(const char* indent, const ElfW(Sym)* syms, const int start, const int nsyms, const char* strtab);
static void print_ver(const char* indent, const ElfW(Versym)* versym, const Elf_Symndx symidx, const ElfW(Verdef)* verdefs, const char* strtab);
static void print_note(const char* indent, const void* datapos, const ElfW(Xword) p_filesz);
#ifdef TFILE
static void print_shdrs(const ElfW(Ehdr)* ehdr, const ElfW(Shdr)* shdr, const ElfW(Half) shnum, const byte_t* filebin);
static const char* shdr_type2str(const ElfW(Word) type);
#endif
static void print_memory(const char* indent, const byte_t* bytes, const int nbytes, const int and_more);
static const char* phdr_type2str(const ElfW(Word) type);
static void print_strtab(const char* indent, const char* pos);
static void print_relas(const char* indent, const ElfW(Rela)* relas, const int nrelas, const ElfW(Sym)* symtab, const char* strtab);
static const char* r_info_type2str(const int type);
static const char* dyn_tag2str(const ElfW(Xword) tag);
static Elf_Symndx lookup_sym_gnu(const char* indent, const uint32_t* hash32, const char* key);
static Elf_Symndx lookup_sym_elf(const char* indent, const uint32_t* hashtab, const char* key, const ElfW(Sym)* symtab, const char* strtab);
static const ElfW(Rela)* lookup_rela_by_name(const char* lookup_name, const ElfW(Rela)* relas, const int nrelas, const ElfW(Sym)* symtab, const char* strtab);
static const char* dt_flags_12str(const int val);
static const char* note_type2str(const uint32_t type);
//
//
//
int main(int argc, char** argv, char** envp)
{
int _nouse = 128;
printf("pid\t%d\n", getpid());
const long pagesize = sysconf(_SC_PAGESIZE);
uintptr_t stack_end = (((uintptr_t)__libc_stack_end + pagesize) & ~(pagesize - 1));
printf("__libc_stack_end=%p pagesize=%ld stack-end=0x%lx\n",
__libc_stack_end, pagesize, stack_end);
const void* faddr = __builtin_frame_address(0);
printf("frame-address=%p(%u)\n", faddr, (uint)faddr);
printf("first-var=%p(%u)\n", &_nouse, (uint)&_nouse);
printf("_start\t%p\n", _start);
printf("main\t%p\n", main);
//printf("_ns_loaded\t%p\n", _rtld_global._dl_ns._ns_loaded);
//printf("__bss_start\t%p\n", __bss_start);
//printf("__bss_end\t%p\n", __bss_end);
// https://linuxjm.osdn.jp/html/LDP_man-pages/man3/end.3.html
printf("First address past:\n");
printf(" program text (etext) %10p\n", &etext);
printf(" initialized data (edata) %10p\n", &edata);
printf(" uninitialized data (end) %10p\n", &end);
dll_main();
printf("env (%p)\n", envp);
char** env = envp;
for (int i=0; *env; i++)
{
printf("\t[%d]\t%.60s%s\n", i, *env, (strlen(*env) > 60) ? "..." : "");
env++;
}
const ElfW(auxv_t)* auxv = (ElfW(auxv_t)*)(env + 1);
printf("auxv (%p)\n", auxv);
for (int i=0; auxv->a_type != AT_NULL; auxv++, i++)
{
printf("\t[%d]\t%lu\t%s\t%lu (%p) #\n",
i, auxv->a_type, auxv_type2str(auxv->a_type),
auxv->a_un.a_val, (void*)auxv->a_un.a_val);
}
#ifdef TFILE
puts("\n*** target is FILE ***\n");
const int fd = open(argv[0], O_RDONLY);
struct stat st;
fstat(fd, &st);
byte_t* filebin = mmap(NULL, st.st_size, PROT_READ, MAP_PRIVATE, fd, 0);
#else
puts("\n*** target is MEMORY ***\n");
const u_long at_base = getauxval(AT_BASE);
const u_long at_phdr = getauxval(AT_PHDR);
const u_long at_entry = getauxval(AT_ENTRY);
printf("AT_SYSINFO_EHDR\t%p ('linux-vdso.so.1')\n", (void*)getauxval(AT_SYSINFO_EHDR));
printf("AT_BASE\t%p ('/lib64/ld-linux-x86-64.so.2')\n", (void*)at_base);
printf("AT_PHDR\t%p\n", (void*)at_phdr);
printf("AT_ENTRY\t%p\n", (void*)at_entry);
#endif
#ifdef TFILE
const ElfW(Ehdr)* ehdr = (ElfW(Ehdr)*)filebin;
printf("Elf_Ehdr (0x0)\n");
#else
const ElfW(Ehdr)* ehdr = (ElfW(Ehdr)*)at_base;
printf("Elf_Ehdr (%p)\n", ehdr);
#endif
puts("\te_ident");
assert(ehdr->e_ident[EI_MAG0] == 0x7f);
assert(ehdr->e_ident[EI_MAG1] == 'E');
assert(ehdr->e_ident[EI_MAG2] == 'L');
assert(ehdr->e_ident[EI_MAG3] == 'F');
assert(ehdr->e_ident[EI_CLASS] == ELFCLASS64);
assert(ehdr->e_ident[EI_DATA] == ELFDATA2LSB);
assert(ehdr->e_ident[EI_VERSION] == EV_CURRENT);
printf("\t\tEI_OSABI\t%d\n", ehdr->e_ident[EI_OSABI]);
printf("\t\tEI_ABIVERSION\t%d\n", ehdr->e_ident[EI_ABIVERSION]);
printf("\te_type\t%d\n", ehdr->e_type);
assert(ehdr->e_machine == 62);
assert(ehdr->e_version == 1);
printf("\te_entry\t%p\n", (void*)ehdr->e_entry);
printf("\te_phoff\t%lu\n", ehdr->e_phoff);
printf("\te_shoff\t%lu (%p)\n", ehdr->e_shoff, (void*)ehdr->e_shoff);
assert(ehdr->e_flags == 0);
printf("\te_ehsize\t%u\n", ehdr->e_ehsize);
assert(ehdr->e_ehsize == sizeof(ElfW(Ehdr)));
printf("\te_phentsize\t%u\n", ehdr->e_phentsize);
assert(ehdr->e_phentsize == sizeof(ElfW(Phdr)));
printf("\te_phnum\t%u\n", ehdr->e_phnum);
printf("\te_shentsize\t%u\n", ehdr->e_shentsize);
assert(ehdr->e_shentsize == sizeof(ElfW(Shdr)));
printf("\te_shnum\t%u\n", ehdr->e_shnum);
printf("\te_shstrndx\t%u\n", ehdr->e_shstrndx);
#ifdef TFILE
const ElfW(Phdr)* elf_phdrs = (ElfW(Phdr)*)&filebin[ehdr->e_phoff];
printf("Elf_Phdr (%p)\n", (void*)ehdr->e_phoff);
/*
for (int i=0; i<ehdr->e_phnum; i++)
{
printf("\tElf_Phdr[%d]\n", i);
print_phdr_members("\t\t", &elf_phdrs[i]);
}
*/
print_phdrs(elf_phdrs, ehdr->e_phnum, filebin);
//
printf("Elf_Shdr (%p)\n", (void*)ehdr->e_shoff);
print_shdrs(ehdr, (ElfW(Shdr)*)&filebin[ehdr->e_shoff], ehdr->e_shnum, filebin);
#else
puts("Elf_Phdr");
//dl_iterate_phdr(phdr_callback, NULL);
phdr_foreach(phdr_callback);
#endif
#ifdef TMEM
const void* v_entry = (void*)at_entry;
printf("v_entry\n");
print_memory("\t", v_entry, 16, 1);
#endif
#ifdef TFILE
munmap(filebin, st.st_size);
close(fd);
#endif
return 0;
}
#ifdef TFILE
static void print_shdrs(const ElfW(Ehdr)* ehdr, const ElfW(Shdr)* shdrs, const ElfW(Half) shnum, const byte_t* filebin)
{
const char* shstrtab = (char*)&filebin[shdrs[ehdr->e_shstrndx].sh_offset];
const ElfW(Sym)* dynsym = NULL;
const char* dynstrtab = NULL;
for (int i=0; i<shnum; i++)
{
const ElfW(Shdr)* shdr = &shdrs[i];
printf("\tElf_Shdr[%d]\n", i);
printf("\t\tsh_name\t%u", shdr->sh_name);
if (shstrtab)
{
printf(" '%s'", &shstrtab[shdr->sh_name]);
}
puts("");
printf("\t\tsh_type\t%u (0x%x)\t%s\n",
shdr->sh_type, shdr->sh_type, shdr_type2str(shdr->sh_type));
printf("\t\tsh_flags\t0x%02lx", shdr->sh_flags);
if (shdr->sh_flags)
{
printf(" (%c%c%c%c%c%c%c%c%c%c%c)",
shdr->sh_flags & SHF_WRITE ? 'W' : '_',
shdr->sh_flags & SHF_ALLOC ? 'A' : '_',
shdr->sh_flags & SHF_EXECINSTR ? 'E' : '_',
shdr->sh_flags & SHF_MERGE ? 'M' : '_',
shdr->sh_flags & SHF_STRINGS ? 'S' : '_',
shdr->sh_flags & SHF_INFO_LINK ? 'I' : '_',
shdr->sh_flags & SHF_LINK_ORDER ? 'L' : '_',
shdr->sh_flags & SHF_OS_NONCONFORMING ? 'O' : '_',
shdr->sh_flags & SHF_GROUP ? 'G' : '_',
shdr->sh_flags & SHF_TLS ? 'T' : '_',
shdr->sh_flags & SHF_MASKOS ? 'm' : '_');
}
puts("");
printf("\t\tsh_addr\t%lu (%p)\n", shdr->sh_addr, (void*)shdr->sh_addr);
printf("\t\tsh_offset\t%lu (%p)\n", shdr->sh_offset, (void*)shdr->sh_offset);
printf("\t\tsh_size\t%lu (0x%lx)\n", shdr->sh_size, shdr->sh_size);
printf("\t\tsh_link\t%u\n", shdr->sh_link);
printf("\t\tsh_info\t%u\n", shdr->sh_info);
printf("\t\tsh_addralign\t%lu\n", shdr->sh_addralign);
printf("\t\tsh_entsize\t%lu\n", shdr->sh_entsize);
const void* filepos = &filebin[shdr->sh_offset];
switch (shdr->sh_type)
{
case SHT_DYNAMIC:
{
print_dyns("\t\t\t", (ElfW(Dyn)*)filepos, filebin);
break;
}
case SHT_SYMTAB:
{
const ElfW(Sym)* syms = (ElfW(Sym)*)filepos;
const int nsyms = shdr->sh_size / shdr->sh_entsize;
const char* strtab = (char*)&filebin[shdrs[shdr->sh_link].sh_offset];
print_syms("\t\t\t", syms, 0, nsyms, strtab);
break;
}
case SHT_DYNSYM:
{
const ElfW(Sym)* syms = (ElfW(Sym)*)filepos;
const int nsyms = shdr->sh_size / shdr->sh_entsize;
const char* strtab = (char*)&filebin[shdrs[shdr->sh_link].sh_offset];
print_syms("\t\t\t", syms, 0, nsyms, strtab);
dynsym = syms;
dynstrtab = strtab;
break;
}
/*
case SHT_DYNSTR:
{
break;
}
*/
case SHT_RELA:
{
const ElfW(Rela)* relas = (ElfW(Rela)*)filepos;
assert(shdr->sh_entsize == sizeof(ElfW(Rela)));
const int nrelas = shdr->sh_size / shdr->sh_entsize;
print_relas("\t\t\t", relas, nrelas, dynsym, dynstrtab);
break;
}
case SHT_INIT_ARRAY:
case SHT_FINI_ARRAY:
{
for (int i=0; i<(shdr->sh_size/shdr->sh_entsize); i++)
{
const unsigned long offset = *((unsigned long*)(filepos + shdr->sh_entsize * i));
printf("\t\t\t[%d]=%p", i, (void*)offset);
print_memory("\t", (byte_t*)(filebin + offset), 16, 1);
}
break;
}
case SHT_NOTE:
{
print_note("\t\t\t", filepos, shdr->sh_size);
break;
}
case SHT_STRTAB:
{
print_strtab("\t\t\t", filepos);
break;
}
default:
{
break;
}
}
}
}
#endif
static const ElfW(Rela)* lookup_rela_by_name(const char* lookup_name, const ElfW(Rela)* relas, const int nrelas, const ElfW(Sym)* symtab, const char* strtab)
{
for (int i=0; i<nrelas; i++)
{
const ElfW(Rela)* rela = (ElfW(Rela)*)&relas[i];
const int r_info_sym = ELF64_R_SYM(rela->r_info);
const char* symname = &strtab[symtab[r_info_sym].st_name];
if (strcmp(lookup_name, symname) == 0)
{
return rela;
}
}
return NULL;
}
static void print_relas(const char* indent, const ElfW(Rela)* relas, const int nrelas, const ElfW(Sym)* symtab, const char* strtab)
{
assert(symtab && strtab);
char* indent1 = alloca(strlen(indent) + 2);
strcpy(indent1, indent);
strcat(indent1, &indent[strlen(indent) - 1]);
const char* pre_name_str = NULL;
int next_dot = 1;
for (int i=0; i<nrelas; i++)
{
const ElfW(Rela)* rela = (ElfW(Rela)*)&relas[i];
const int r_info_sym = ELF64_R_SYM(rela->r_info);
const int r_info_type = ELF64_R_TYPE(rela->r_info);
const char* st_name_str = &strtab[symtab[r_info_sym].st_name];
if (pre_name_str && pre_name_str[0] == '\0' && st_name_str[0] == '\0' && i<(nrelas - 1))
{
if (next_dot)
{
// skip
printf("%s...\n", indent);
}
next_dot = 0;
}
else
{
printf("%sRela[%d]\n", indent, i);
printf("%sr_offset\t%p\n", indent1, (void*)rela->r_offset);
printf("%sr_info(sym)\t%d\t'%s'\n", indent1, r_info_sym, st_name_str);
printf("%sr_info(typ)\t%d\t%s\n", indent1, r_info_type, r_info_type2str(r_info_type));
printf("%sr_addend\t%ld\n", indent1, rela->r_addend);
next_dot = 1;
}
pre_name_str = st_name_str;
}
}
static void print_strtab(const char* indent, const char* pos)
{
const char* start = pos;
pos++;
const char* last = NULL;
int i;
for (i=0; *pos; i++)
{
if (i < 20)
{
printf("%s\t%d: (%ld) '%s'\n", indent, i, pos - start, pos);
}
last = pos;
pos = pos + strlen(pos) + 1;
}
if (i > 20)
{
printf("%s\t\t...\n", indent);
printf("%s\t%d: (%ld) '%s'\n", indent, i, last - start, last);
}
}
#ifdef TFILE
#define D_UN_VAL(ba, v) (v.d_val)
#else
#define D_UN_VAL(ba, v) ((ba) + (v.d_val))
#endif
static void print_dyns(const char* indent, const ElfW(Dyn)* dyns, const byte_t* baseadr)
{
char* indent1 = alloca(strlen(indent) + 2);
strcpy(indent1, indent);
strcat(indent1, &indent[strlen(indent) - 1]);
char* indent2 = alloca(strlen(indent1) + 2);
strcpy(indent2, indent1);
strcat(indent2, &indent1[strlen(indent1) - 1]);
char* indent3 = alloca(strlen(indent2) + 2);
strcpy(indent3, indent2);
strcat(indent3, &indent2[strlen(indent2) - 1]);
char* indent4 = alloca(strlen(indent3) + 2);
strcpy(indent4, indent3);
strcat(indent4, &indent3[strlen(indent3) - 1]);
const char* strtab = NULL;
for (int i=0; dyns[i].d_un.d_val != DT_NULL; i++)
{
const ElfW(Dyn)* dyn = &dyns[i];
if (dyn->d_tag == DT_STRTAB)
{
#ifdef TFILE
strtab = (char*)(baseadr + dyn->d_un.d_val);
#else
strtab = (char*)dyn->d_un.d_ptr;
#endif
break;
}
}
//assert(strtab);
ElfW(Addr) init_array = 0;
ElfW(Addr) fini_array = 0;
const ElfW(Sym)* symtab = NULL;
ElfW(Addr) hashtab_gnu = 0;
ElfW(Addr) hashtab_elf = 0;
const ElfW(Rela)* relas = NULL;
ElfW(Xword) relasz = 0;
const ElfW(Rela)* pltrelas = NULL;
ElfW(Xword) pltrelsz = 0;
ElfW(Addr) pltgot = 0;
const ElfW(Verneed)* verneeds = NULL;
const ElfW(Verdef)* verdefs = NULL;
for (int idx=0; dyns[idx].d_un.d_val != DT_NULL; idx++)
{
const ElfW(Dyn)* dyn = &dyns[idx];
printf("%sElf_Dyn[%d]\n", indent, idx);
printf("%s\td_tag\t%ld (%p)\t%s\n",
indent, dyn->d_tag, (void*)dyn->d_tag, dyn_tag2str(dyn->d_tag));
switch (dyn->d_tag)
{
case DT_SONAME:
case DT_NEEDED:
{
printf("%s\t%lu (%p)", indent, dyn->d_un.d_val, (void*)dyn->d_un.d_ptr);
if (strtab)
{
printf("%s\t'%s'", indent, &strtab[dyn->d_un.d_val]);
}
printf("\n");
break;
}
case DT_STRTAB:
{
printf("%s\t%p\n", indent, (void*)dyn->d_un.d_ptr);
print_strtab(indent1, (char*)strtab);
break;
}
case DT_STRSZ:
{
printf("%s\t%lu\n", indent, dyn->d_un.d_val);
break;
}
case DT_INIT:
{
printf("%s\t%p (%p)\n",
indent, (void*)dyn->d_un.d_ptr, (void*)D_UN_VAL(baseadr, dyn->d_un));
print_memory(indent2, (byte_t*)(baseadr + dyn->d_un.d_val), 16, 1);
break;
}
case DT_FINI:
{
printf("%s\t%p (%p)\n",
indent, (void*)dyn->d_un.d_ptr, (void*)D_UN_VAL(baseadr, dyn->d_un));
print_memory(indent2, baseadr + dyn->d_un.d_val, 16, 1);
break;
}
case DT_INIT_ARRAY:
{
#ifdef TMEM
//#ifdef TFILE
// init_array = baseadr + dyn->d_un.d_val;
//#else
init_array = dyn->d_un.d_ptr;
#endif
printf("%s\t%p (%p)\n",
indent, (void*)dyn->d_un.d_ptr, (void*)D_UN_VAL(baseadr, dyn->d_un));
break;
}
case DT_FINI_ARRAY:
{
#ifdef TMEM
//#ifdef TFILE
// fini_array = baseadr + dyn->d_un.d_val;
//#endif
fini_array = dyn->d_un.d_ptr;
#endif
printf("%s\t%p(%p)\n",
indent, (void*)dyn->d_un.d_ptr, (void*)(baseadr + dyn->d_un.d_ptr));
break;
}
case DT_INIT_ARRAYSZ:
{
printf("%s\t%lu\n", indent, dyn->d_un.d_val);
if (init_array)
{
const ElfW(Addr)* arr = (ElfW(Addr)*)(baseadr + init_array);
for (int i=0; i<(dyn->d_un.d_val/sizeof(ElfW(Addr))); i++)
{
printf("%s\t[%d]=%p\n", indent, i, (void*)arr[i]);
print_memory(indent2, (byte_t*)arr[i], 16, 1);
}
}
break;
}
case DT_FINI_ARRAYSZ:
{
printf("%s\t%lu\n", indent, dyn->d_un.d_val);
if (fini_array)
{
const ElfW(Addr)* arr = (ElfW(Addr)*)(baseadr + fini_array);
for (int i=0; i<(dyn->d_un.d_val/sizeof(ElfW(Addr))); i++)
{
printf("%s\t[%d]=%p\n", indent, i, (void*)arr[i]);
print_memory(indent2, (byte_t*)arr[i], 16, 1);
}
}
break;
}
case DT_HASH:
{
// https://github.com/robgjansen/elf-loader/blob/master/vdl-lookup.c#L118
// https://flapenguin.me/elf-dt-hash
#ifdef TFILE
hashtab_elf = (ElfW(Addr))(baseadr + dyn->d_un.d_ptr);
#else
hashtab_elf = (ElfW(Addr))dyn->d_un.d_ptr;
#endif
printf("%s\t%p\n", indent, (void*)hashtab_elf);
print_memory(indent2, (byte_t*)hashtab_elf, 16, 1);
break;
}
case DT_GNU_HASH:
{
// https://blogs.oracle.com/solaris/post/gnu-hash-elf-sections
// https://chowdera.com/2021/06/20210617215010995Q.html
#ifdef TFILE
hashtab_gnu = (ElfW(Addr))(baseadr + dyn->d_un.d_ptr);
#else
hashtab_gnu = (ElfW(Addr))dyn->d_un.d_ptr;
#endif
printf("%s\t%p\n", indent, (void*)hashtab_gnu);
print_memory(indent2, (byte_t*)hashtab_gnu, 16, 1);
break;
}
case DT_SYMTAB:
{
#ifdef TFILE
symtab = (ElfW(Sym)*)(baseadr + dyn->d_un.d_val);
#else
symtab = (ElfW(Sym)*)dyn->d_un.d_ptr;
#endif
printf("%s\t%p\n", indent, (void*)symtab);
break;
}
case DT_SYMENT:
{
printf("%s\t%lu:%lu\n", indent, dyn->d_un.d_val, sizeof(Elf64_Sym));
break;
}
// Rela -->
case DT_RELA:
{
printf("%s\t%p\n", indent, (void*)dyn->d_un.d_ptr);
relas = (ElfW(Rela)*)dyn->d_un.d_ptr;
break;
}
case DT_RELASZ:
{
printf("%s\t%lu\n", indent, dyn->d_un.d_val);
relasz = dyn->d_un.d_val;
break;
}
case DT_RELAENT:
{
printf("%s\t%lu\n", indent, dyn->d_un.d_val);
assert(relas);
assert(relasz);
const ElfW(Xword) relaent = dyn->d_un.d_val;
assert(relaent == sizeof(ElfW(Rela)));
const int nrelas = relasz / relaent;
print_relas(indent2, relas, nrelas, symtab, strtab);
break;
}
// Rela <--
// Plt -->
case DT_PLTGOT:
{
printf("%s%p\n", indent1, (void*)dyn->d_un.d_val);
pltgot = dyn->d_un.d_val;
break;
}
case DT_PLTRELSZ:
{
printf("%s%lu\n", indent1, dyn->d_un.d_val);
pltrelsz = dyn->d_un.d_val;
break;
}
case DT_PLTREL:
{
printf("%s%lu\n", indent1, dyn->d_un.d_val);
assert(dyn->d_un.d_val == DT_RELA);
break;
}
case DT_JMPREL:
{
// https://github.com/r0ngwe1/elfloader/blob/master/elf_loader.c
assert(pltrelsz);
const ElfW(Xword) npltrelas = pltrelsz / sizeof(ElfW(Rela));
pltrelas = (ElfW(Rela)*)dyn->d_un.d_val;
print_relas(indent2, pltrelas, npltrelas, symtab, strtab);
// GOT
assert(pltgot);
const char* lookup_name = "opendir";
printf("%s((got TEST S)) lookup('%s')\n", indent2, lookup_name);
const ElfW(Rela)* rela = lookup_rela_by_name(lookup_name,
pltrelas, npltrelas, symtab, strtab);
if (rela)
{
printf("%s\tr_offset=%p\n", indent2, (void*)rela->r_offset);
const void* got = baseadr + rela->r_offset;
printf("%s\tgot=%p\n", indent2, got);
const ElfW(Addr) bef_addr = *(ElfW(Addr)*)got;
printf("%s\tbefore addr=%p\n", indent2, (void*)bef_addr);
print_memory(indent4, (byte_t*)bef_addr, 16, 1);
DIR* dirp = opendir("/etc/");
const ElfW(Addr) aft_addr = *(ElfW(Addr)*)got;
printf("%s\tafter addr=%p\n", indent2, (void*)aft_addr);
print_memory(indent4, (byte_t*)aft_addr, 16, 1);
closedir(dirp);
}
printf("%s((got TEST E)) lookup('%s')\n", indent2, lookup_name);
break;
}
// Plt <--
// Ver -->
// https://code.nsnam.org/mathieu/elf-loader/file/tip/vdl-reloc.c
case DT_VERDEF:
{
verdefs = (ElfW(Verdef)*)(baseadr + dyn->d_un.d_ptr);
printf("%s%p\n", indent1, verdefs);
break;
}
case DT_VERDEFNUM:
{
printf("%s%lu\n", indent1, dyn->d_un.d_val);
printf("%s* sizeof(Verdef)=%lu\n", indent1, sizeof(ElfW(Verdef)));
printf("%s* sizeof(Verdaux)=%lu\n", indent1, sizeof(ElfW(Verdaux)));
const ElfW(Verdef)* verdef = verdefs;
for (int i=0; i<dyn->d_un.d_val; i++)
{
const int prt = i < 5 || i == (dyn->d_un.d_val - 1);
if (prt)
{
printf("%sVerdef[%d]\n", indent1, i);
printf("%svd_version\t%d\n", indent2, verdef->vd_version);
printf("%svd_flags\t%d\n", indent2, verdef->vd_flags);
printf("%svd_ndx\t%d\n", indent2, verdef->vd_ndx);
printf("%svd_cnt\t%d\n", indent2, verdef->vd_cnt);
printf("%svd_aux\t%u\n", indent2, verdef->vd_aux);
printf("%svd_next\t%u\n", indent2, verdef->vd_next);
}
if (i == 5)
{
printf("%s...\n", indent2);
}
const byte_t* aux_pos = ((byte_t*)verdef) + verdef->vd_aux;
const ElfW(Verdaux)* verdauxs = (ElfW(Verdaux)*)aux_pos;
const ElfW(Verdaux)* verdaux = verdauxs;
for (int j=0; j<verdef->vd_cnt; j++)
{
const char* vda_name = &strtab[verdaux->vda_name];
if (prt)
{
printf("%sVerdaux[%d]\n", indent2, j);
printf("%s\tvda_name\t%u\t'%s'\n", indent2, verdaux->vda_name, vda_name);
printf("%s\tvda_next\t%u\n", indent2, verdaux->vda_next);
}
const byte_t* vda_next_pos = ((byte_t*)verdaux) + verdaux->vda_next;
verdaux = (ElfW(Verdaux)*)vda_next_pos;
}
assert(! verdaux->vda_next);
const byte_t* vd_next_pos = ((byte_t*)verdef) + verdef->vd_next;
verdef = (ElfW(Verdef)*)vd_next_pos;
}
assert(! verdef->vd_next);
break;
}
case DT_VERNEED:
{
verneeds = (ElfW(Verneed)*)(baseadr + dyn->d_un.d_ptr);
printf("%s%p\n", indent1, verneeds);
break;
}
case DT_VERNEEDNUM:
{
printf("%s%lu\n", indent1, dyn->d_un.d_val);
printf("%s* sizeof(Verneed)=%lu\n", indent1, sizeof(ElfW(Verneed)));
printf("%s* sizeof(Vernaux)=%lu\n", indent1, sizeof(ElfW(Vernaux)));
const ElfW(Verneed)* verneed = verneeds;
for (int i=0; i<dyn->d_un.d_val; i++)
{
printf("%sVerneed[%d]\n", indent1, i);
printf("%svn_version\t%d\n", indent2, verneed->vn_version);
printf("%svn_cnt\t%d\n", indent2, verneed->vn_cnt);
printf("%svn_file\t%u\t'%s'\n",
indent2, verneed->vn_file, &strtab[verneed->vn_file]);
printf("%svn_aux\t%u\n", indent2, verneed->vn_aux);
printf("%svn_next\t%u\n", indent2, verneed->vn_next);
const byte_t* aux_pos = ((byte_t*)verneed) + verneed->vn_aux;
const ElfW(Vernaux)* vernauxs = (ElfW(Vernaux)*)aux_pos;
const ElfW(Vernaux)* vernaux = vernauxs;
for (int j=0; j<verneed->vn_cnt; j++)
{
printf("%sVernaux[%d]\n", indent2, j);
const char* vna_name = &strtab[vernaux->vna_name];
printf("%s\tvna_hash\t%u\n", indent2, vernaux->vna_hash);
printf("%s\tvna_name\t%u\t'%s'\n", indent2, vernaux->vna_name, vna_name);
printf("%s\tvna_flags\t%u\n", indent2, vernaux->vna_flags);
printf("%s\tvna_next\t%u\n", indent2, vernaux->vna_next);
printf("%s\t* vna_name hash=%u\n", indent2, new_hash_elf(vna_name));
const byte_t* vna_next_pos = ((byte_t*)vernaux) + vernaux->vna_next;
vernaux = (ElfW(Vernaux)*)vna_next_pos;
}
assert(! vernaux->vna_next);
const byte_t* vn_next_pos = ((byte_t*)verneed) + verneed->vn_next;
verneed = (ElfW(Verneed)*)vn_next_pos;
}
assert(! verneed->vn_next);
break;
}
case DT_VERSYM:
{
printf("%sd_un.d_val=%lu (%p)\n", indent1, dyn->d_un.d_val, (void*)dyn->d_un.d_ptr);
const ElfW(Versym)* versym = (ElfW(Versym)*)dyn->d_un.d_ptr;
//const char* lookup_name = "opendir";
const char* lookup_name = "_rtld_global";
if (hashtab_gnu)
{
printf("%s((gnu TEST S)) lookup('%s')\n", indent1, lookup_name);
const Elf_Symndx symidx = lookup_sym_gnu(
indent2, (uint32_t*)hashtab_gnu, lookup_name);
printf("%s((gnu RESULT)) =>%u\n", indent1, symidx);
if (symidx && symtab)
{
print_syms(indent2, symtab, symidx, 1, strtab);
const ElfW(Sym)* sym = &symtab[symidx];
if (sym->st_size)
{
printf("%s\t* addr=%p\n", indent3, baseadr + sym->st_value);
print_memory(indent4, baseadr + sym->st_value,
MIN(16, sym->st_value), sym->st_value <= 16 ? 0 : 1);
}