From 08de37f245e3544522406f988a683a3388e6afe0 Mon Sep 17 00:00:00 2001
From: Kasper <kasper.sauramo@pm.me>
Date: Wed, 23 Apr 2025 09:35:17 +0300
Subject: [PATCH] drafting the got/plt changes

---
 src/moduler/moduler.c | 96 ++++++++++++++++++++++++++++++++++++++++---
 src/symbols.h         |  2 +
 2 files changed, 93 insertions(+), 5 deletions(-)

diff --git a/src/moduler/moduler.c b/src/moduler/moduler.c
index 80a7436..a0dbc7f 100644
--- a/src/moduler/moduler.c
+++ b/src/moduler/moduler.c
@@ -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;
 }
 
diff --git a/src/symbols.h b/src/symbols.h
index 1d308e6..93c0484 100644
--- a/src/symbols.h
+++ b/src/symbols.h
@@ -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;