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 | } |