| cfd23479 |
1 | #include <stdio.h> |
| 2 | #include <stdlib.h> |
| 3 | #include <string.h> |
| 4 | #include <linux/coff.h> |
| 5 | #include <assert.h> |
| 6 | #include <stdint.h> |
| 7 | |
| 8 | /* http://www.delorie.com/djgpp/doc/coff/ */ |
| 9 | |
| 10 | typedef struct { |
| 11 | unsigned short f_magic; /* magic number */ |
| 12 | unsigned short f_nscns; /* number of sections */ |
| 13 | unsigned int f_timdat; /* time & date stamp */ |
| 14 | unsigned int f_symptr; /* file pointer to symtab */ |
| 15 | unsigned int f_nsyms; /* number of symtab entries */ |
| 16 | unsigned short f_opthdr; /* sizeof(optional hdr) */ |
| 17 | unsigned short f_flags; /* flags */ |
| 18 | } FILHDR; |
| 19 | |
| 20 | typedef struct { |
| 21 | unsigned short magic; /* type of file */ |
| 22 | unsigned short vstamp; /* version stamp */ |
| 23 | unsigned int tsize; /* text size in bytes, padded to FW bdry*/ |
| 24 | unsigned int dsize; /* initialized data " " */ |
| 25 | unsigned int bsize; /* uninitialized data " " */ |
| 26 | unsigned int entry; /* entry pt. */ |
| 27 | unsigned int text_start; /* base of text used for this file */ |
| 28 | unsigned int data_start; /* base of data used for this file */ |
| 29 | } AOUTHDR; |
| 30 | |
| 31 | typedef struct { |
| 32 | char s_name[8]; /* section name */ |
| 33 | unsigned int s_paddr; /* physical address, aliased s_nlib */ |
| 34 | unsigned int s_vaddr; /* virtual address */ |
| 35 | unsigned int s_size; /* section size */ |
| 36 | unsigned int s_scnptr; /* file ptr to raw data for section */ |
| 37 | unsigned int s_relptr; /* file ptr to relocation */ |
| 38 | unsigned int s_lnnoptr; /* file ptr to line numbers */ |
| 39 | unsigned short s_nreloc; /* number of relocation entries */ |
| 40 | unsigned short s_nlnno; /* number of line number entries */ |
| 41 | unsigned int s_flags; /* flags */ |
| 42 | } SCNHDR; |
| 43 | |
| 44 | typedef struct { |
| 45 | unsigned int r_vaddr; /* address of relocation */ |
| 46 | unsigned int r_symndx; /* symbol we're adjusting for */ |
| 47 | unsigned short r_type; /* type of relocation */ |
| 48 | } __attribute__((packed)) RELOC; |
| 49 | |
| 50 | static void my_assert_(int line, const char *name, long v, long expect, int is_eq) |
| 51 | { |
| 52 | int ok; |
| 53 | if (is_eq) |
| 54 | ok = (v == expect); |
| 55 | else |
| 56 | ok = (v != expect); |
| 57 | |
| 58 | if (!ok) |
| 59 | { |
| 60 | printf("%d: '%s' is %lx, need %s%lx\n", line, name, |
| 61 | v, is_eq ? "" : "!", expect); |
| 62 | exit(1); |
| 63 | } |
| 64 | } |
| 65 | #define my_assert(v, exp) \ |
| 66 | my_assert_(__LINE__, #v, (long)(v), (long)(exp), 1) |
| 67 | #define my_assert_not(v, exp) \ |
| 68 | my_assert_(__LINE__, #v, (long)(v), (long)(exp), 0) |
| 69 | |
| 70 | void parse_headers(FILE *f, unsigned int *base_out, |
| 71 | long *sect_ofs, uint8_t **sect_data, long *sect_sz, |
| 72 | RELOC **relocs, long *reloc_cnt) |
| 73 | { |
| 74 | unsigned int base = 0; |
| 75 | long opthdr_pos; |
| 76 | long reloc_size; |
| 77 | FILHDR hdr; |
| 78 | AOUTHDR opthdr; |
| 79 | SCNHDR scnhdr; |
| 80 | int s, val; |
| 81 | int ret; |
| 82 | |
| 83 | ret = fread(&hdr, 1, sizeof(hdr), f); |
| 84 | my_assert(ret, sizeof(hdr)); |
| 85 | |
| 86 | if (hdr.f_magic == 0x5a4d) // MZ |
| 87 | { |
| 88 | ret = fseek(f, 0x3c, SEEK_SET); |
| 89 | my_assert(ret, 0); |
| 90 | ret = fread(&val, 1, sizeof(val), f); |
| 91 | my_assert(ret, sizeof(val)); |
| 92 | |
| 93 | ret = fseek(f, val, SEEK_SET); |
| 94 | my_assert(ret, 0); |
| 95 | ret = fread(&val, 1, sizeof(val), f); |
| 96 | my_assert(ret, sizeof(val)); |
| 97 | my_assert(val, 0x4550); // PE |
| 98 | |
| 99 | // should be COFF now |
| 100 | ret = fread(&hdr, 1, sizeof(hdr), f); |
| 101 | my_assert(ret, sizeof(hdr)); |
| 102 | } |
| 103 | |
| 104 | my_assert(hdr.f_magic, COFF_I386MAGIC); |
| 105 | |
| 106 | if (hdr.f_opthdr != 0) |
| 107 | { |
| 108 | opthdr_pos = ftell(f); |
| 109 | |
| 110 | if (hdr.f_opthdr < sizeof(opthdr)) |
| 111 | my_assert(1, 0); |
| 112 | |
| 113 | ret = fread(&opthdr, 1, sizeof(opthdr), f); |
| 114 | my_assert(ret, sizeof(opthdr)); |
| 115 | my_assert(opthdr.magic, COFF_ZMAGIC); |
| 116 | |
| 117 | printf("text_start: %x\n", opthdr.text_start); |
| 118 | |
| 119 | if (hdr.f_opthdr > sizeof(opthdr)) { |
| 120 | ret = fread(&base, 1, sizeof(base), f); |
| 121 | my_assert(ret, sizeof(base)); |
| 122 | printf("base: %x\n", base); |
| 123 | } |
| 124 | ret = fseek(f, opthdr_pos + hdr.f_opthdr, SEEK_SET); |
| 125 | my_assert(ret, 0); |
| 126 | } |
| 127 | |
| 128 | for (s = 0; s < hdr.f_nscns; s++) { |
| 129 | ret = fread(&scnhdr, 1, sizeof(scnhdr), f); |
| 130 | my_assert(ret, sizeof(scnhdr)); |
| 131 | |
| 132 | if (scnhdr.s_size != 0) |
| 133 | break; |
| 134 | } |
| 135 | |
| 136 | printf("s_name: '%s'\n", scnhdr.s_name); |
| 137 | printf("s_vaddr: %x\n", scnhdr.s_vaddr); |
| 138 | printf("s_size: %x\n", scnhdr.s_size); |
| 139 | printf("s_scnptr: %x\n", scnhdr.s_scnptr); |
| 140 | printf("s_nreloc: %x\n", scnhdr.s_nreloc); |
| 141 | printf("--\n"); |
| 142 | |
| 143 | ret = fseek(f, scnhdr.s_scnptr, SEEK_SET); |
| 144 | my_assert(ret, 0); |
| 145 | |
| 146 | *sect_data = malloc(scnhdr.s_size); |
| 147 | my_assert_not(*sect_data, NULL); |
| 148 | ret = fread(*sect_data, 1, scnhdr.s_size, f); |
| 149 | my_assert(ret, scnhdr.s_size); |
| 150 | |
| 151 | *sect_ofs = scnhdr.s_scnptr; |
| 152 | *sect_sz = scnhdr.s_size; |
| 153 | |
| 154 | ret = fseek(f, scnhdr.s_relptr, SEEK_SET); |
| 155 | my_assert(ret, 0); |
| 156 | |
| 157 | reloc_size = scnhdr.s_nreloc * sizeof((*relocs)[0]); |
| 158 | *relocs = malloc(reloc_size + 1); |
| 159 | my_assert_not(*relocs, NULL); |
| 160 | ret = fread(*relocs, 1, reloc_size, f); |
| 161 | my_assert(ret, reloc_size); |
| 162 | |
| 163 | *reloc_cnt = scnhdr.s_nreloc; |
| 164 | |
| 165 | if (base != 0) |
| 166 | *base_out = base + scnhdr.s_vaddr; |
| 167 | } |
| 168 | |
| 169 | static int handle_pad(uint8_t *d_obj, uint8_t *d_exe, int maxlen) |
| 170 | { |
| 171 | static const uint8_t p7[7] = { 0x8d, 0xa4, 0x24, 0x00, 0x00, 0x00, 0x00 }; |
| 172 | static const uint8_t p6[6] = { 0x8d, 0x9b, 0x00, 0x00, 0x00, 0x00 }; |
| 173 | static const uint8_t p5[5] = { 0x05, 0x00, 0x00, 0x00, 0x00 }; |
| 174 | static const uint8_t p4[4] = { 0x8d, 0x64, 0x24, 0x00 }; |
| 175 | static const uint8_t p3[3] = { 0x8d, 0x49, 0x00 }; |
| 176 | static const uint8_t p2[2] = { 0x8b, 0xff }; |
| 177 | static const uint8_t p1[1] = { 0x90 }; |
| 178 | int len; |
| 179 | int i; |
| 180 | |
| 181 | for (i = 0; i < maxlen; i++) |
| 182 | if (d_exe[i] != 0xcc) |
| 183 | break; |
| 184 | |
| 185 | for (len = i; len > 0; ) |
| 186 | { |
| 187 | i = len; |
| 188 | if (i > 7) |
| 189 | i = 7; |
| 190 | |
| 191 | switch (i) { |
| 192 | #define CASE(x) \ |
| 193 | case sizeof(p ## x): \ |
| 194 | if (memcmp(d_obj, p ## x, sizeof(p ## x))) \ |
| 195 | return 0; \ |
| 196 | memset(d_obj, 0xcc, sizeof(p ## x)); \ |
| 197 | break; |
| 198 | CASE(7) |
| 199 | CASE(6) |
| 200 | CASE(5) |
| 201 | CASE(4) |
| 202 | CASE(3) |
| 203 | CASE(2) |
| 204 | CASE(1) |
| 205 | default: |
| 206 | printf("%s: unhandled len: %d\n", __func__, len); |
| 207 | return 0; |
| 208 | #undef CASE |
| 209 | } |
| 210 | |
| 211 | len -= i; |
| 212 | d_obj += i; |
| 213 | } |
| 214 | |
| 215 | return 1; |
| 216 | } |
| 217 | |
| 218 | struct equiv_opcode { |
| 219 | signed char len; |
| 220 | signed char ofs; |
| 221 | short cmp_rm; |
| 222 | uint8_t v_masm[8]; |
| 223 | uint8_t v_masm_mask[8]; |
| 224 | uint8_t v_msvc[8]; |
| 225 | uint8_t v_msvc_mask[8]; |
| 226 | } equiv_ops[] = { |
| 227 | // cmp $0x11,%ax |
| 228 | { 4, -1, 0, |
| 229 | { 0x66,0x83,0xf8,0x03 }, { 0xff,0xff,0xff,0x00 }, |
| 230 | { 0x66,0x3d,0x03,0x00 }, { 0xff,0xff,0x00,0xff }, }, |
| 231 | // lea -0x1(%ebx,%eax,1),%esi // op mod/rm sib offs |
| 232 | // mov, test, imm grp 1 |
| 233 | { 3, -2, 1, |
| 234 | { 0x8d,0x74,0x03 }, { 0xf0,0x07,0xc0 }, |
| 235 | { 0x8d,0x74,0x18 }, { 0xf0,0x07,0xc0 }, }, |
| 236 | // movzbl 0x58f24a(%eax,%ecx,1),%eax |
| 237 | { 4, -3, 1, |
| 238 | { 0x0f,0xb6,0x84,0x08 }, { 0xff,0xff,0x07,0xc0 }, |
| 239 | { 0x0f,0xb6,0x84,0x01 }, { 0xff,0xff,0x07,0xc0 }, }, |
| 240 | // inc/dec |
| 241 | { 3, -2, 1, |
| 242 | { 0xfe,0x4c,0x03 }, { 0xfe,0xff,0xc0 }, |
| 243 | { 0xfe,0x4c,0x18 }, { 0xfe,0xff,0xc0 }, }, |
| 244 | // cmp |
| 245 | { 3, -2, 1, |
| 246 | { 0x38,0x0c,0x0c }, { 0xff,0xff,0xc0 }, |
| 247 | { 0x38,0x0c,0x30 }, { 0xff,0xff,0xc0 }, }, |
| 248 | // test %dl,%bl |
| 249 | { 2, -1, 1, |
| 250 | { 0x84,0xd3 }, { 0xfe,0xc0 }, |
| 251 | { 0x84,0xda }, { 0xfe,0xc0 }, }, |
| 252 | // cmp r,r/m vs rm/r |
| 253 | { 2, 0, 1, |
| 254 | { 0x3a,0xca }, { 0xff,0xc0 }, |
| 255 | { 0x38,0xd1 }, { 0xff,0xc0 }, }, |
| 256 | // rep + 66 prefix |
| 257 | { 2, 0, 0, |
| 258 | { 0xf3,0x66 }, { 0xfe,0xff }, |
| 259 | { 0x66,0xf3 }, { 0xff,0xfe }, }, |
| 260 | // fadd st, st(0) vs st(0), st |
| 261 | { 2, 0, 0, |
| 262 | { 0xd8,0xc0 }, { 0xff,0xf7 }, |
| 263 | { 0xdc,0xc0 }, { 0xff,0xf7 }, }, |
| 264 | |
| 265 | // broad filters (may take too much..) |
| 266 | // testb $0x4,0x1d(%esi,%eax,1) |
| 267 | // movb, push, .. |
| 268 | { 3, -2, 1, |
| 269 | { 0xf6,0x44,0x06 }, { 0x00,0x07,0xc0 }, |
| 270 | { 0xf6,0x44,0x30 }, { 0x00,0x07,0xc0 }, }, |
| 271 | }; |
| 272 | |
| 273 | static int cmp_mask(uint8_t *d, uint8_t *expect, uint8_t *mask, int len) |
| 274 | { |
| 275 | int i; |
| 276 | |
| 277 | for (i = 0; i < len; i++) |
| 278 | if ((d[i] & mask[i]) != (expect[i] & mask[i])) |
| 279 | return 1; |
| 280 | |
| 281 | return 0; |
| 282 | } |
| 283 | |
| 284 | static int check_equiv(uint8_t *d_obj, uint8_t *d_exe, int maxlen) |
| 285 | { |
| 286 | uint8_t vo, ve, vo2, ve2; |
| 287 | int i, jo, je; |
| 288 | int len, ofs; |
| 289 | |
| 290 | for (i = 0; i < sizeof(equiv_ops) / sizeof(equiv_ops[0]); i++) |
| 291 | { |
| 292 | struct equiv_opcode *op = &equiv_ops[i]; |
| 293 | |
| 294 | len = op->len; |
| 295 | if (maxlen < len) |
| 296 | continue; |
| 297 | |
| 298 | ofs = op->ofs; |
| 299 | if (cmp_mask(d_obj + ofs, op->v_masm, |
| 300 | op->v_masm_mask, len)) |
| 301 | continue; |
| 302 | if (cmp_mask(d_exe + ofs, op->v_msvc, |
| 303 | op->v_msvc_mask, len)) |
| 304 | continue; |
| 305 | |
| 306 | jo = je = 0; |
| 307 | d_obj += ofs; |
| 308 | d_exe += ofs; |
| 309 | while (1) |
| 310 | { |
| 311 | for (; jo < len; jo++) |
| 312 | if (op->v_masm_mask[jo] != 0xff) |
| 313 | break; |
| 314 | for (; je < len; je++) |
| 315 | if (op->v_msvc_mask[je] != 0xff) |
| 316 | break; |
| 317 | |
| 318 | if ((jo == len && je != len) || (jo != len && je == len)) { |
| 319 | printf("invalid equiv_ops\n"); |
| 320 | return -1; |
| 321 | } |
| 322 | if (jo == len) |
| 323 | return len + ofs - 1; // matched |
| 324 | |
| 325 | // var byte |
| 326 | vo = d_obj[jo] & ~op->v_masm_mask[jo]; |
| 327 | ve = d_exe[je] & ~op->v_msvc_mask[je]; |
| 328 | if (op->cmp_rm && op->v_masm_mask[jo] == 0xc0) { |
| 329 | vo2 = vo >> 3; |
| 330 | vo &= 7; |
| 331 | ve2 = ve & 7; |
| 332 | ve >>= 3; |
| 333 | if (vo != ve || vo2 != ve2) |
| 334 | return -1; |
| 335 | } |
| 336 | else { |
| 337 | if (vo != ve) |
| 338 | return -1; |
| 339 | } |
| 340 | |
| 341 | jo++; |
| 342 | je++; |
| 343 | } |
| 344 | } |
| 345 | |
| 346 | return -1; |
| 347 | } |
| 348 | |
| 349 | int main(int argc, char *argv[]) |
| 350 | { |
| 351 | FILE *f_obj, *f_exe; |
| 352 | long text_ofs_obj, text_ofs_exe; |
| 353 | long sztext_obj, sztext_exe, sztext_cmn; |
| 354 | RELOC *relocs_obj, *relocs_exe; |
| 355 | long reloc_cnt_obj, reloc_cnt_exe, reloc_cnt_cmn; |
| 356 | unsigned int base = 0; |
| 357 | uint8_t *d_obj, *d_exe; |
| 358 | int retval = 1; |
| 359 | int left; |
| 360 | int ret; |
| 361 | int i; |
| 362 | |
| 363 | if (argc != 3) { |
| 364 | printf("usage:\n%s <obj> <exe>\n", argv[0]); |
| 365 | return 1; |
| 366 | } |
| 367 | |
| 368 | f_obj = fopen(argv[1], "r+b"); |
| 369 | if (f_obj == NULL) { |
| 370 | fprintf(stderr, "%s", argv[1]); |
| 371 | perror(""); |
| 372 | return 1; |
| 373 | } |
| 374 | |
| 375 | f_exe = fopen(argv[2], "r"); |
| 376 | if (f_exe == NULL) { |
| 377 | fprintf(stderr, "%s", argv[1]); |
| 378 | perror(""); |
| 379 | return 1; |
| 380 | } |
| 381 | |
| 382 | parse_headers(f_obj, &base, &text_ofs_obj, &d_obj, &sztext_obj, |
| 383 | &relocs_obj, &reloc_cnt_obj); |
| 384 | parse_headers(f_exe, &base, &text_ofs_exe, &d_exe, &sztext_exe, |
| 385 | &relocs_exe, &reloc_cnt_exe); |
| 386 | |
| 387 | sztext_cmn = sztext_obj; |
| 388 | if (sztext_cmn > sztext_exe) |
| 389 | sztext_cmn = sztext_exe; |
| 390 | reloc_cnt_cmn = reloc_cnt_obj; |
| 391 | if (reloc_cnt_cmn > reloc_cnt_exe) |
| 392 | reloc_cnt_cmn = reloc_cnt_exe; |
| 393 | |
| 394 | if (sztext_cmn == 0) { |
| 395 | printf("bad .text size(s): %ld, %ld\n", |
| 396 | sztext_obj, sztext_exe); |
| 397 | return 1; |
| 398 | } |
| 399 | |
| 400 | for (i = 0; i < reloc_cnt_obj; i++) // reloc_cnt_cmn |
| 401 | { |
| 402 | unsigned int a = relocs_obj[i].r_vaddr; |
| 403 | //printf("%04x %08x\n", relocs_obj[i].r_type, a); |
| 404 | |
| 405 | switch (relocs_obj[i].r_type) { |
| 406 | case 0x06: |
| 407 | memset(d_obj + a, 0, 4); |
| 408 | memset(d_exe + a, 0, 4); |
| 409 | break; |
| 410 | default: |
| 411 | printf("unknown reloc %x @%08x\n", |
| 412 | relocs_obj[i].r_type, base + a); |
| 413 | return 1; |
| 414 | } |
| 415 | } |
| 416 | |
| 417 | for (i = 0; i < sztext_cmn; i++) |
| 418 | { |
| 419 | if (d_obj[i] == d_exe[i]) |
| 420 | continue; |
| 421 | |
| 422 | left = sztext_cmn - i; |
| 423 | |
| 424 | if (d_exe[i] == 0xcc) { // padding |
| 425 | if (handle_pad(d_obj + i, d_exe + i, left)) |
| 426 | continue; |
| 427 | } |
| 428 | |
| 429 | ret = check_equiv(d_obj + i, d_exe + i, left); |
| 430 | if (ret >= 0) { |
| 431 | i += ret; |
| 432 | continue; |
| 433 | } |
| 434 | |
| 435 | printf("%x: %02x vs %02x\n", base + i, d_obj[i], d_exe[i]); |
| 436 | goto out; |
| 437 | } |
| 438 | |
| 439 | out: |
| 440 | return retval; |
| 441 | } |
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