4 #include <linux/coff.h>
10 /* http://www.delorie.com/djgpp/doc/coff/ */
13 unsigned short f_magic; /* magic number */
14 unsigned short f_nscns; /* number of sections */
15 unsigned int f_timdat; /* time & date stamp */
16 unsigned int f_symptr; /* file pointer to symtab */
17 unsigned int f_nsyms; /* number of symtab entries */
18 unsigned short f_opthdr; /* sizeof(optional hdr) */
19 unsigned short f_flags; /* flags */
23 unsigned short magic; /* type of file */
24 unsigned short vstamp; /* version stamp */
25 unsigned int tsize; /* text size in bytes, padded to FW bdry*/
26 unsigned int dsize; /* initialized data " " */
27 unsigned int bsize; /* uninitialized data " " */
28 unsigned int entry; /* entry pt. */
29 unsigned int text_start; /* base of text used for this file */
30 unsigned int data_start; /* base of data used for this file */
34 char s_name[8]; /* section name */
35 unsigned int s_paddr; /* physical address, aliased s_nlib */
36 unsigned int s_vaddr; /* virtual address */
37 unsigned int s_size; /* section size */
38 unsigned int s_scnptr; /* file ptr to raw data for section */
39 unsigned int s_relptr; /* file ptr to relocation */
40 unsigned int s_lnnoptr; /* file ptr to line numbers */
41 unsigned short s_nreloc; /* number of relocation entries */
42 unsigned short s_nlnno; /* number of line number entries */
43 unsigned int s_flags; /* flags */
47 unsigned int r_vaddr; /* address of relocation */
48 unsigned int r_symndx; /* symbol we're adjusting for */
49 unsigned short r_type; /* type of relocation */
50 } __attribute__((packed)) RELOC;
54 char e_name[E_SYMNMLEN];
56 unsigned int e_zeroes;
57 unsigned int e_offset;
62 unsigned short e_type;
63 unsigned char e_sclass;
64 unsigned char e_numaux;
65 } __attribute__((packed)) SYMENT;
71 unsigned int fpos; // for patching
85 static int symt_cmp(const void *p1_, const void *p2_)
87 const struct my_symtab *p1 = p1_, *p2 = p2_;
88 return p1->addr - p2->addr;
91 void parse_headers(FILE *f, unsigned int *base_out,
92 struct my_sect_info *sect_i,
93 struct my_symtab **symtab_out, long *sym_cnt)
95 struct my_symtab *symt_o = NULL;
96 char *stringtab = NULL;
97 unsigned int base = 0;
110 ret = fseek(f, 0, SEEK_END);
115 ret = fseek(f, 0, SEEK_SET);
118 ret = fread(&hdr, 1, sizeof(hdr), f);
119 my_assert(ret, sizeof(hdr));
121 if (hdr.f_magic == 0x5a4d) // MZ
123 ret = fseek(f, 0x3c, SEEK_SET);
125 ret = fread(&val, 1, sizeof(val), f);
126 my_assert(ret, sizeof(val));
128 ret = fseek(f, val, SEEK_SET);
130 ret = fread(&val, 1, sizeof(val), f);
131 my_assert(ret, sizeof(val));
132 my_assert(val, 0x4550); // PE
134 // should be COFF now
135 ret = fread(&hdr, 1, sizeof(hdr), f);
136 my_assert(ret, sizeof(hdr));
139 my_assert(hdr.f_magic, COFF_I386MAGIC);
141 if (hdr.f_opthdr != 0)
143 opthdr_pos = ftell(f);
145 if (hdr.f_opthdr < sizeof(opthdr))
148 ret = fread(&opthdr, 1, sizeof(opthdr), f);
149 my_assert(ret, sizeof(opthdr));
150 my_assert(opthdr.magic, COFF_ZMAGIC);
152 //printf("text_start: %x\n", opthdr.text_start);
154 if (hdr.f_opthdr > sizeof(opthdr)) {
155 ret = fread(&base, 1, sizeof(base), f);
156 my_assert(ret, sizeof(base));
157 //printf("base: %x\n", base);
159 ret = fseek(f, opthdr_pos + hdr.f_opthdr, SEEK_SET);
163 // note: assuming first non-empty one is .text ..
164 for (s = 0; s < hdr.f_nscns; s++) {
165 sect_i->scnhdr_fofs = ftell(f);
167 ret = fread(&scnhdr, 1, sizeof(scnhdr), f);
168 my_assert(ret, sizeof(scnhdr));
170 if (scnhdr.s_size != 0) {
175 my_assert(s < hdr.f_nscns, 1);
178 printf("f_nsyms: %x\n", hdr.f_nsyms);
179 printf("s_name: '%s'\n", scnhdr.s_name);
180 printf("s_vaddr: %x\n", scnhdr.s_vaddr);
181 printf("s_size: %x\n", scnhdr.s_size);
182 //printf("s_scnptr: %x\n", scnhdr.s_scnptr);
183 printf("s_nreloc: %x\n", scnhdr.s_nreloc);
187 ret = fseek(f, scnhdr.s_scnptr, SEEK_SET);
190 sect_i->data = malloc(scnhdr.s_size);
191 my_assert_not(sect_i->data, NULL);
192 ret = fread(sect_i->data, 1, scnhdr.s_size, f);
193 my_assert(ret, scnhdr.s_size);
195 sect_i->sect_fofs = scnhdr.s_scnptr;
196 sect_i->size = scnhdr.s_size;
199 ret = fseek(f, scnhdr.s_relptr, SEEK_SET);
202 reloc_size = scnhdr.s_nreloc * sizeof(sect_i->relocs[0]);
203 sect_i->relocs = malloc(reloc_size + 1);
204 my_assert_not(sect_i->relocs, NULL);
205 ret = fread(sect_i->relocs, 1, reloc_size, f);
206 my_assert(ret, reloc_size);
208 sect_i->reloc_cnt = scnhdr.s_nreloc;
209 sect_i->reloc_fofs = scnhdr.s_relptr;
211 if (base != 0 && base_out != NULL)
212 *base_out = base + scnhdr.s_vaddr;
214 if (symtab_out == NULL || sym_cnt == NULL)
218 if (hdr.f_nsyms != 0) {
221 symt_o = malloc(hdr.f_nsyms * sizeof(symt_o[0]) + 1);
222 my_assert_not(symt_o, NULL);
224 ret = fseek(f, hdr.f_symptr
225 + hdr.f_nsyms * sizeof(syment), SEEK_SET);
227 ret = fread(&i, 1, sizeof(i), f);
228 my_assert(ret, sizeof(i));
229 my_assert((unsigned int)i < filesize, 1);
231 stringtab = malloc(i);
232 my_assert_not(stringtab, NULL);
233 memset(stringtab, 0, 4);
234 ret = fread(stringtab + 4, 1, i - 4, f);
235 my_assert(ret, i - 4);
237 ret = fseek(f, hdr.f_symptr, SEEK_SET);
241 for (i = s = 0; i < hdr.f_nsyms; i++) {
244 ret = fread(&syment, 1, sizeof(syment), f);
245 my_assert(ret, sizeof(syment));
247 strncpy(symname, syment.e.e_name, 8);
248 //printf("%3d %2d %08x '%s'\n", syment.e_sclass,
249 // syment.e_scnum, syment.e_value, symname);
251 if (syment.e_scnum != text_scnum || syment.e_sclass != C_EXT)
254 symt_o[s].addr = syment.e_value;
255 symt_o[s].fpos = pos;
256 if (syment.e.e.e_zeroes == 0)
257 symt_o[s].name = stringtab + syment.e.e.e_offset;
259 symt_o[s].name = strdup(symname);
262 if (syment.e_numaux) {
263 ret = fseek(f, syment.e_numaux * sizeof(syment),
266 i += syment.e_numaux;
271 qsort(symt_o, s, sizeof(symt_o[0]), symt_cmp);
274 *symtab_out = symt_o;
277 static int handle_pad(uint8_t *d_obj, uint8_t *d_exe, int maxlen)
279 static const uint8_t p7[7] = { 0x8d, 0xa4, 0x24, 0x00, 0x00, 0x00, 0x00 };
280 static const uint8_t p6[6] = { 0x8d, 0x9b, 0x00, 0x00, 0x00, 0x00 };
281 static const uint8_t p5[5] = { 0x05, 0x00, 0x00, 0x00, 0x00 };
282 static const uint8_t p4[4] = { 0x8d, 0x64, 0x24, 0x00 };
283 static const uint8_t p3[3] = { 0x8d, 0x49, 0x00 };
284 static const uint8_t p2[2] = { 0x8b, 0xff };
285 static const uint8_t p1[1] = { 0x90 };
289 for (i = 0; i < maxlen; i++)
290 if (d_exe[i] != 0xcc)
293 for (len = i; len > 0; )
301 case sizeof(p ## x): \
302 if (memcmp(d_obj, p ## x, sizeof(p ## x))) \
304 memset(d_obj, 0xcc, sizeof(p ## x)); \
314 printf("%s: unhandled len: %d\n", __func__, len);
326 struct equiv_opcode {
331 uint8_t v_masm_mask[8];
333 uint8_t v_msvc_mask[8];
337 { 0x66,0x83,0xf8,0x03 }, { 0xff,0xff,0xff,0x00 },
338 { 0x66,0x3d,0x03,0x00 }, { 0xff,0xff,0x00,0xff }, },
339 // lea -0x1(%ebx,%eax,1),%esi // op mod/rm sib offs
340 // mov, test, imm grp 1
342 { 0x8d,0x74,0x03 }, { 0xf0,0x07,0xc0 },
343 { 0x8d,0x74,0x18 }, { 0xf0,0x07,0xc0 }, },
344 // movzbl 0x58f24a(%eax,%ecx,1),%eax
346 { 0x0f,0xb6,0x84,0x08 }, { 0xff,0xff,0x07,0xc0 },
347 { 0x0f,0xb6,0x84,0x01 }, { 0xff,0xff,0x07,0xc0 }, },
350 { 0xfe,0x4c,0x03 }, { 0xfe,0xff,0xc0 },
351 { 0xfe,0x4c,0x18 }, { 0xfe,0xff,0xc0 }, },
354 { 0x38,0x0c,0x0c }, { 0xff,0xff,0xc0 },
355 { 0x38,0x0c,0x30 }, { 0xff,0xff,0xc0 }, },
358 { 0x84,0xd3 }, { 0xfe,0xc0 },
359 { 0x84,0xda }, { 0xfe,0xc0 }, },
362 { 0x3a,0xca }, { 0xff,0xc0 },
363 { 0x38,0xd1 }, { 0xff,0xc0 }, },
366 { 0xf3,0x66 }, { 0xfe,0xff },
367 { 0x66,0xf3 }, { 0xff,0xfe }, },
368 // fadd st, st(0) vs st(0), st
370 { 0xd8,0xc0 }, { 0xff,0xf7 },
371 { 0xdc,0xc0 }, { 0xff,0xf7 }, },
373 // broad filters (may take too much..)
374 // testb $0x4,0x1d(%esi,%eax,1)
377 { 0xf6,0x44,0x06 }, { 0x00,0x07,0xc0 },
378 { 0xf6,0x44,0x30 }, { 0x00,0x07,0xc0 }, },
381 static int cmp_mask(uint8_t *d, uint8_t *expect, uint8_t *mask, int len)
385 for (i = 0; i < len; i++)
386 if ((d[i] & mask[i]) != (expect[i] & mask[i]))
392 static int check_equiv(uint8_t *d_obj, uint8_t *d_exe, int maxlen)
394 uint8_t vo, ve, vo2, ve2;
398 for (i = 0; i < sizeof(equiv_ops) / sizeof(equiv_ops[0]); i++)
400 struct equiv_opcode *op = &equiv_ops[i];
407 if (cmp_mask(d_obj + ofs, op->v_masm,
408 op->v_masm_mask, len))
410 if (cmp_mask(d_exe + ofs, op->v_msvc,
411 op->v_msvc_mask, len))
419 for (; jo < len; jo++)
420 if (op->v_masm_mask[jo] != 0xff)
422 for (; je < len; je++)
423 if (op->v_msvc_mask[je] != 0xff)
426 if ((jo == len && je != len) || (jo != len && je == len)) {
427 printf("invalid equiv_ops\n");
431 return len + ofs - 1; // matched
434 vo = d_obj[jo] & ~op->v_masm_mask[jo];
435 ve = d_exe[je] & ~op->v_msvc_mask[je];
436 if (op->cmp_rm && op->v_masm_mask[jo] == 0xc0) {
441 if (vo != ve || vo2 != ve2)
457 static void fill_int3(unsigned char *d, int len)
466 int main(int argc, char *argv[])
468 struct my_sect_info s_text_obj, s_text_exe;
469 struct my_symtab *syms_obj = NULL;
472 unsigned int base = 0, addr, end;
481 printf("usage:\n%s <a_obj> <exe>\n", argv[0]);
485 f_obj = fopen(argv[1], "r+b");
487 fprintf(stderr, "%s", argv[1]);
492 f_exe = fopen(argv[2], "r");
494 fprintf(stderr, "%s", argv[2]);
499 parse_headers(f_obj, NULL, &s_text_obj, &syms_obj, &sym_cnt_obj);
500 parse_headers(f_exe, &base, &s_text_exe, NULL, NULL);
502 sztext_cmn = s_text_obj.size;
503 if (sztext_cmn > s_text_exe.size)
504 sztext_cmn = s_text_exe.size;
506 if (sztext_cmn == 0) {
507 printf("bad .text size(s): %ld, %ld\n",
508 s_text_obj.size, s_text_exe.size);
512 for (i = 0; i < s_text_obj.reloc_cnt; i++)
514 unsigned int a = s_text_obj.relocs[i].r_vaddr;
515 //printf("%04x %08x\n", s_text_obj.relocs[i].r_type, a);
517 switch (s_text_obj.relocs[i].r_type) {
518 case 0x06: // RELOC_ADDR32
519 case 0x14: // RELOC_REL32
520 // must preserve stored val,
521 // so trash exe so that cmp passes
522 memcpy(s_text_exe.data + a, s_text_obj.data + a, 4);
525 printf("unknown reloc %x @%08x/%08x\n",
526 s_text_obj.relocs[i].r_type, a, base + a);
531 for (i = 0; i < sztext_cmn; i++)
533 if (s_text_obj.data[i] == s_text_exe.data[i])
536 left = sztext_cmn - i;
538 if (s_text_exe.data[i] == 0xcc) { // padding
539 if (handle_pad(s_text_obj.data + i,
540 s_text_exe.data + i, left))
544 ret = check_equiv(s_text_obj.data + i, s_text_exe.data + i, left);
550 printf("%x: %02x vs %02x\n", base + i,
551 s_text_obj.data[i], s_text_exe.data[i]);
555 // fill removed funcs with 'int3'
556 for (i = 0; i < sym_cnt_obj; i++) {
557 if (strncmp(syms_obj[i].name, "rm_", 3))
560 addr = syms_obj[i].addr;
561 end = (i < sym_cnt_obj - 1)
562 ? syms_obj[i + 1].addr : s_text_obj.size;
563 if (addr >= s_text_obj.size || end > s_text_obj.size) {
564 printf("addr OOR: %x-%x '%s'\n", addr, end,
568 fill_int3(s_text_obj.data + addr, end - addr);
572 for (i = 0; i < s_text_obj.reloc_cnt; i++) {
573 addr = s_text_obj.relocs[i].r_vaddr;
574 if (addr > s_text_obj.size - 4) {
575 printf("reloc addr OOR: %x\n", addr);
578 if (*(unsigned int *)(s_text_obj.data + addr) == 0xcccccccc) {
579 memmove(&s_text_obj.relocs[i],
580 &s_text_obj.relocs[i + 1],
581 (s_text_obj.reloc_cnt - i - 1)
582 * sizeof(s_text_obj.relocs[0]));
584 s_text_obj.reloc_cnt--;
589 ret = fseek(f_obj, s_text_obj.sect_fofs, SEEK_SET);
591 ret = fwrite(s_text_obj.data, 1, s_text_obj.size, f_obj);
592 my_assert(ret, s_text_obj.size);
595 ret = fseek(f_obj, s_text_obj.reloc_fofs, SEEK_SET);
597 ret = fwrite(s_text_obj.relocs, sizeof(s_text_obj.relocs[0]),
598 s_text_obj.reloc_cnt, f_obj);
599 my_assert(ret, s_text_obj.reloc_cnt);
601 ret = fseek(f_obj, s_text_obj.scnhdr_fofs, SEEK_SET);
603 ret = fread(&tmphdr, 1, sizeof(tmphdr), f_obj);
604 my_assert(ret, sizeof(tmphdr));
606 tmphdr.s_nreloc = s_text_obj.reloc_cnt;
608 ret = fseek(f_obj, s_text_obj.scnhdr_fofs, SEEK_SET);
610 ret = fwrite(&tmphdr, 1, sizeof(tmphdr), f_obj);
611 my_assert(ret, sizeof(tmphdr));