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drafting the got/plt changes

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This commit is contained in:
Kasper
2025-04-23 09:35:17 +03:00
parent 57b47cec64
commit 08de37f245
2 changed files with 93 additions and 5 deletions
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96
src/moduler/moduler.c
View File

@@ -9,6 +9,7 @@
#include "types.h"
#include <dlfcn.h>
#include <elf.h>
#include <errno.h>
#include <fcntl.h>
#include <gelf.h>
@@ -138,8 +139,9 @@ cleanup:
return ret;
}
static HiloadResult moduler_apply_module_patch(const char *module_name, const char *patch_name,
struct sc_array_memreg *memregs) {
static HiloadResult
moduler_apply_module_patch(const char *module_name, const char *patch_name,
struct sc_array_memreg *memregs) {
MemoryRegionSpan patch_memory = memory_get_module_span(memregs, patch_name);
void *patch_base = (void *)patch_memory.region_start;
@@ -157,13 +159,97 @@ static HiloadResult moduler_apply_module_patch(const char *module_name, const ch
void *module_base = (void *)module_memory.region_start;
size_t module_size = module_memory.region_end - module_memory.region_start;
ElfW(Rela) *rela = NULL;
ElfW(Sym) *symtab = NULL;
char *strtab = NULL;
size_t rela_size = 0;
Elf *elf = NULL;
GElf_Phdr *dyn_sct = hi_elf_find_dynamic_segment(module_base, module_size, &elf);
(void)dyn_sct;
// TODO: cont
ElfW(Dyn) *dyn_sct =
hi_elf_find_dynamic_segment(module_base, module_size, &elf);
for (ElfW(Dyn) *d = dyn_sct; d->d_tag != DT_NULL; d++) {
switch (d->d_tag) {
case DT_JMPREL:
rela = (ElfW(Rela) *)d->d_un.d_ptr;
break;
case DT_PLTRELSZ:
rela_size = d->d_un.d_val;
break;
case DT_SYMTAB:
symtab = (ElfW(Sym)*)d->d_un.d_ptr;
break;
case DT_STRTAB:
strtab = (char *)d->d_un.d_ptr;
break;
}
}
// Adjust relative pointers by adding the module base address
if (rela && ((void *)rela < module_base ||
(void *)rela >= (void *)((char *)module_base + module_size))) {
rela = (ElfW(Rela) *)((char *)module_base + (uintptr_t)rela);
}
if (symtab &&
((void *)symtab < module_base ||
(void *)symtab >= (void *)((char *)module_base + module_size))) {
symtab = (ElfW(Sym) *)((char *)module_base + (uintptr_t)symtab);
}
if (strtab &&
((void *)strtab < module_base ||
(void *)strtab >= (void *)((char *)module_base + module_size))) {
strtab = (char *)module_base + (uintptr_t)strtab;
}
if (!rela || !symtab || !strtab || rela_size == 0) {
log_error("Missing required dynamic information\n");
elf_end(elf);
return HILOAD_FAIL;
}
// Process relocations to find GOT entries
int found_count = 0;
size_t rela_count = rela_size / sizeof(ElfW(Rela));
printf("Processing %zu relocations\n", rela_count);
size_t num_symbols = 0;
for (size_t i = 0; i < rela_count; i++) {
ElfW(Rela)* r = &rela[i];
int sym_idx = ElfW(R_SYM)(r->r_info);
int rel_type = ElfW(R_TYPE)(r->r_info);
// We're only interested in JMP_SLOT relocations (GOT entries for functions)
if (rel_type != R_X86_64_JUMP_SLOT && rel_type != R_386_JMP_SLOT) {
continue;
}
ElfW(Sym)* sym = &symtab[sym_idx];
char* name = strtab + sym->st_name;
/* // Calculate the GOT entry address */
/* void** got_entry = (void**)((char*)module_base + r->r_offset); */
/* // Check if this is a symbol we want to patch */
/* for (int j = 0; j < num_symbols; j++) { */
/* if (strcmp(symbols[j].name, name) == 0) { */
/* symbols[j].got_entry = got_entry; */
/* symbols[j].orig_addr = *got_entry; // Save the original function pointer */
/* printf("Found GOT entry for '%s' at %p (points to %p)\n", */
/* name, got_entry, *got_entry); */
/* found_count++; */
/* break; */
/* } */
/* } */
}
symbol_term_symbols(&symbols);
elf_end(elf);
return ret;
}

2
src/symbols.h
View File

@@ -26,6 +26,8 @@ typedef struct HiSymbol {
HiSymbolBind binding;
HiSymbolType type;
void *address;
void **got_entry;
void *orig_address;
} HiSymbol;
sc_array_def(HiSymbol, sym);
typedef struct sc_array_sym HiSymbols;