1 /*-
2 * SPDX-License-Identifier: BSD-2-Clause
3 *
4 * Copyright (c) 2014 The FreeBSD Foundation
5 *
6 * This software was developed by Edward Tomasz Napierala under sponsorship
7 * from the FreeBSD Foundation.
8 *
9 * Redistribution and use in source and binary forms, with or without
10 * modification, are permitted provided that the following conditions
11 * are met:
12 * 1. Redistributions of source code must retain the above copyright
13 * notice, this list of conditions and the following disclaimer.
14 * 2. Redistributions in binary form must reproduce the above copyright
15 * notice, this list of conditions and the following disclaimer in the
16 * documentation and/or other materials provided with the distribution.
17 *
18 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
19 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
20 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
21 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
22 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
23 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
24 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
25 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
26 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
27 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
28 * SUCH DAMAGE.
29 *
30 */
31
32 /*
33 * PE format reference:
34 * http://www.microsoft.com/whdc/system/platform/firmware/PECOFF.mspx
35 */
36
37 #include <sys/cdefs.h>
38 #include <assert.h>
39 #include <err.h>
40 #include <errno.h>
41 #include <stddef.h>
42 #include <stdio.h>
43 #include <stdint.h>
44 #include <stdlib.h>
45 #include <string.h>
46 #include <unistd.h>
47
48 #include "uefisign.h"
49
50 #ifndef CTASSERT
51 #define CTASSERT(x) _CTASSERT(x, __LINE__)
52 #define _CTASSERT(x, y) __CTASSERT(x, y)
53 #define __CTASSERT(x, y) typedef char __assert_ ## y [(x) ? 1 : -1]
54 #endif
55
56 #define PE_ALIGMENT_SIZE 8
57
58 struct mz_header {
59 uint8_t mz_signature[2];
60 uint8_t mz_dont_care[58];
61 uint16_t mz_lfanew;
62 } __attribute__((packed));
63
64 struct coff_header {
65 uint8_t coff_dont_care[2];
66 uint16_t coff_number_of_sections;
67 uint8_t coff_dont_care_either[16];
68 } __attribute__((packed));
69
70 #define PE_SIGNATURE 0x00004550
71
72 struct pe_header {
73 uint32_t pe_signature;
74 struct coff_header pe_coff;
75 } __attribute__((packed));
76
77 #define PE_OPTIONAL_MAGIC_32 0x010B
78 #define PE_OPTIONAL_MAGIC_32_PLUS 0x020B
79
80 #define PE_OPTIONAL_SUBSYSTEM_EFI_APPLICATION 10
81 #define PE_OPTIONAL_SUBSYSTEM_EFI_BOOT 11
82 #define PE_OPTIONAL_SUBSYSTEM_EFI_RUNTIME 12
83
84 struct pe_optional_header_32 {
85 uint16_t po_magic;
86 uint8_t po_dont_care[58];
87 uint32_t po_size_of_headers;
88 uint32_t po_checksum;
89 uint16_t po_subsystem;
90 uint8_t po_dont_care_either[22];
91 uint32_t po_number_of_rva_and_sizes;
92 } __attribute__((packed));
93
94 CTASSERT(offsetof(struct pe_optional_header_32, po_size_of_headers) == 60);
95 CTASSERT(offsetof(struct pe_optional_header_32, po_checksum) == 64);
96 CTASSERT(offsetof(struct pe_optional_header_32, po_subsystem) == 68);
97 CTASSERT(offsetof(struct pe_optional_header_32, po_number_of_rva_and_sizes) == 92);
98
99 struct pe_optional_header_32_plus {
100 uint16_t po_magic;
101 uint8_t po_dont_care[58];
102 uint32_t po_size_of_headers;
103 uint32_t po_checksum;
104 uint16_t po_subsystem;
105 uint8_t po_dont_care_either[38];
106 uint32_t po_number_of_rva_and_sizes;
107 } __attribute__((packed));
108
109 CTASSERT(offsetof(struct pe_optional_header_32_plus, po_size_of_headers) == 60);
110 CTASSERT(offsetof(struct pe_optional_header_32_plus, po_checksum) == 64);
111 CTASSERT(offsetof(struct pe_optional_header_32_plus, po_subsystem) == 68);
112 CTASSERT(offsetof(struct pe_optional_header_32_plus, po_number_of_rva_and_sizes) == 108);
113
114 #define PE_DIRECTORY_ENTRY_CERTIFICATE 4
115
116 struct pe_directory_entry {
117 uint32_t pde_rva;
118 uint32_t pde_size;
119 } __attribute__((packed));
120
121 struct pe_section_header {
122 uint8_t psh_dont_care[16];
123 uint32_t psh_size_of_raw_data;
124 uint32_t psh_pointer_to_raw_data;
125 uint8_t psh_dont_care_either[16];
126 } __attribute__((packed));
127
128 CTASSERT(offsetof(struct pe_section_header, psh_size_of_raw_data) == 16);
129 CTASSERT(offsetof(struct pe_section_header, psh_pointer_to_raw_data) == 20);
130
131 #define PE_CERTIFICATE_REVISION 0x0200
132 #define PE_CERTIFICATE_TYPE 0x0002
133
134 struct pe_certificate {
135 uint32_t pc_len;
136 uint16_t pc_revision;
137 uint16_t pc_type;
138 char pc_signature[0];
139 } __attribute__((packed));
140
141 void
range_check(const struct executable * x,off_t off,size_t len,const char * name)142 range_check(const struct executable *x, off_t off, size_t len,
143 const char *name)
144 {
145
146 if (off < 0) {
147 errx(1, "%s starts at negative offset %jd",
148 name, (intmax_t)off);
149 }
150 if (off >= (off_t)x->x_len) {
151 errx(1, "%s starts at %jd, past the end of executable at %zd",
152 name, (intmax_t)off, x->x_len);
153 }
154 if (len >= x->x_len) {
155 errx(1, "%s size %zd is larger than the executable size %zd",
156 name, len, x->x_len);
157 }
158 if (off + len > x->x_len) {
159 errx(1, "%s extends to %jd, past the end of executable at %zd",
160 name, (intmax_t)(off + len), x->x_len);
161 }
162 }
163
164 size_t
signature_size(const struct executable * x)165 signature_size(const struct executable *x)
166 {
167 const struct pe_directory_entry *pde;
168
169 range_check(x, x->x_certificate_entry_off,
170 x->x_certificate_entry_len, "Certificate Directory");
171
172 pde = (struct pe_directory_entry *)
173 (x->x_buf + x->x_certificate_entry_off);
174
175 if (pde->pde_rva != 0 && pde->pde_size == 0)
176 warnx("signature size is 0, but its RVA is %d", pde->pde_rva);
177 if (pde->pde_rva == 0 && pde->pde_size != 0)
178 warnx("signature RVA is 0, but its size is %d", pde->pde_size);
179
180 return (pde->pde_size);
181 }
182
183 void
show_certificate(const struct executable * x)184 show_certificate(const struct executable *x)
185 {
186 struct pe_certificate *pc;
187 const struct pe_directory_entry *pde;
188
189 range_check(x, x->x_certificate_entry_off,
190 x->x_certificate_entry_len, "Certificate Directory");
191
192 pde = (struct pe_directory_entry *)
193 (x->x_buf + x->x_certificate_entry_off);
194
195 if (signature_size(x) == 0) {
196 printf("file not signed\n");
197 return;
198 }
199
200 #if 0
201 printf("certificate chunk at offset %zd, size %zd\n",
202 pde->pde_rva, pde->pde_size);
203 #endif
204
205 range_check(x, pde->pde_rva, pde->pde_size, "Certificate chunk");
206
207 pc = (struct pe_certificate *)(x->x_buf + pde->pde_rva);
208 if (pc->pc_revision != PE_CERTIFICATE_REVISION) {
209 errx(1, "wrong certificate chunk revision, is %d, should be %d",
210 pc->pc_revision, PE_CERTIFICATE_REVISION);
211 }
212 if (pc->pc_type != PE_CERTIFICATE_TYPE) {
213 errx(1, "wrong certificate chunk type, is %d, should be %d",
214 pc->pc_type, PE_CERTIFICATE_TYPE);
215 }
216 printf("to dump PKCS7:\n "
217 "dd if='%s' bs=1 skip=%zd | openssl pkcs7 -inform DER -print\n",
218 x->x_path, pde->pde_rva + offsetof(struct pe_certificate, pc_signature));
219 printf("to dump raw ASN.1:\n "
220 "openssl asn1parse -i -inform DER -offset %zd -in '%s'\n",
221 pde->pde_rva + offsetof(struct pe_certificate, pc_signature), x->x_path);
222 }
223
224 static void
parse_section_table(struct executable * x,off_t off,int number_of_sections)225 parse_section_table(struct executable *x, off_t off, int number_of_sections)
226 {
227 const struct pe_section_header *psh;
228 int i;
229
230 range_check(x, off, sizeof(*psh) * number_of_sections,
231 "section table");
232
233 if (x->x_headers_len < off + sizeof(*psh) * number_of_sections)
234 errx(1, "section table outside of headers");
235
236 psh = (const struct pe_section_header *)(x->x_buf + off);
237
238 if (number_of_sections >= MAX_SECTIONS) {
239 errx(1, "too many sections: got %d, should be %d",
240 number_of_sections, MAX_SECTIONS);
241 }
242 x->x_nsections = number_of_sections;
243
244 for (i = 0; i < number_of_sections; i++) {
245 if (psh->psh_size_of_raw_data > 0 &&
246 psh->psh_pointer_to_raw_data < x->x_headers_len)
247 errx(1, "section points inside the headers");
248
249 range_check(x, psh->psh_pointer_to_raw_data,
250 psh->psh_size_of_raw_data, "section");
251 #if 0
252 printf("section %d: start %d, size %d\n",
253 i, psh->psh_pointer_to_raw_data, psh->psh_size_of_raw_data);
254 #endif
255 x->x_section_off[i] = psh->psh_pointer_to_raw_data;
256 x->x_section_len[i] = psh->psh_size_of_raw_data;
257 psh++;
258 }
259 }
260
261 static void
parse_directory(struct executable * x,off_t off,int number_of_rva_and_sizes,int number_of_sections)262 parse_directory(struct executable *x, off_t off,
263 int number_of_rva_and_sizes, int number_of_sections)
264 {
265 //int i;
266 const struct pe_directory_entry *pde;
267
268 //printf("Data Directory at offset %zd\n", off);
269
270 if (number_of_rva_and_sizes <= PE_DIRECTORY_ENTRY_CERTIFICATE) {
271 errx(1, "wrong NumberOfRvaAndSizes %d; should be at least %d",
272 number_of_rva_and_sizes, PE_DIRECTORY_ENTRY_CERTIFICATE);
273 }
274
275 range_check(x, off, sizeof(*pde) * number_of_rva_and_sizes,
276 "PE Data Directory");
277 if (x->x_headers_len <= off + sizeof(*pde) * number_of_rva_and_sizes)
278 errx(1, "PE Data Directory outside of headers");
279
280 x->x_certificate_entry_off =
281 off + sizeof(*pde) * PE_DIRECTORY_ENTRY_CERTIFICATE;
282 x->x_certificate_entry_len = sizeof(*pde);
283 #if 0
284 printf("certificate directory entry at offset %zd, len %zd\n",
285 x->x_certificate_entry_off, x->x_certificate_entry_len);
286
287 pde = (struct pe_directory_entry *)(x->x_buf + off);
288 for (i = 0; i < number_of_rva_and_sizes; i++) {
289 printf("rva %zd, size %zd\n", pde->pde_rva, pde->pde_size);
290 pde++;
291 }
292 #endif
293
294 return (parse_section_table(x,
295 off + sizeof(*pde) * number_of_rva_and_sizes, number_of_sections));
296 }
297
298 /*
299 * The PE checksum algorithm is undocumented; this code is mostly based on
300 * http://forum.sysinternals.com/optional-header-checksum-calculation_topic24214.html
301 *
302 * "Sum the entire image file, excluding the CheckSum field in the optional
303 * header, as an array of USHORTs, allowing any carry above 16 bits to be added
304 * back onto the low 16 bits. Then add the file size to get a 32-bit value."
305 *
306 * Note that most software does not care about the checksum at all; perhaps
307 * we could just set it to 0 instead.
308 *
309 * XXX: Endianness?
310 */
311 static uint32_t
compute_checksum(const struct executable * x)312 compute_checksum(const struct executable *x)
313 {
314 uint32_t cksum = 0;
315 uint16_t tmp;
316 int i;
317
318 range_check(x, x->x_checksum_off, x->x_checksum_len, "PE checksum");
319
320 assert(x->x_checksum_off % 2 == 0);
321
322 for (i = 0; i + sizeof(tmp) < x->x_len; i += 2) {
323 /*
324 * Don't checksum the checksum. The +2 is because the checksum
325 * is 4 bytes, and here we're iterating over 2 byte chunks.
326 */
327 if (i == x->x_checksum_off || i == x->x_checksum_off + 2) {
328 tmp = 0;
329 } else {
330 assert(i + sizeof(tmp) <= x->x_len);
331 memcpy(&tmp, x->x_buf + i, sizeof(tmp));
332 }
333
334 cksum += tmp;
335 cksum += cksum >> 16;
336 cksum &= 0xffff;
337 }
338
339 cksum += cksum >> 16;
340 cksum &= 0xffff;
341
342 cksum += x->x_len;
343
344 return (cksum);
345 }
346
347 static void
parse_optional_32_plus(struct executable * x,off_t off,int number_of_sections)348 parse_optional_32_plus(struct executable *x, off_t off,
349 int number_of_sections)
350 {
351 #if 0
352 uint32_t computed_checksum;
353 #endif
354 const struct pe_optional_header_32_plus *po;
355
356 range_check(x, off, sizeof(*po), "PE Optional Header");
357
358 po = (struct pe_optional_header_32_plus *)(x->x_buf + off);
359 switch (po->po_subsystem) {
360 case PE_OPTIONAL_SUBSYSTEM_EFI_APPLICATION:
361 case PE_OPTIONAL_SUBSYSTEM_EFI_BOOT:
362 case PE_OPTIONAL_SUBSYSTEM_EFI_RUNTIME:
363 break;
364 default:
365 errx(1, "wrong PE Optional Header subsystem 0x%x",
366 po->po_subsystem);
367 }
368
369 #if 0
370 printf("subsystem %d, checksum 0x%x, %d data directories\n",
371 po->po_subsystem, po->po_checksum, po->po_number_of_rva_and_sizes);
372 #endif
373
374 x->x_checksum_off = off +
375 offsetof(struct pe_optional_header_32_plus, po_checksum);
376 x->x_checksum_len = sizeof(po->po_checksum);
377 #if 0
378 printf("checksum 0x%x at offset %zd, len %zd\n",
379 po->po_checksum, x->x_checksum_off, x->x_checksum_len);
380
381 computed_checksum = compute_checksum(x);
382 if (computed_checksum != po->po_checksum) {
383 warnx("invalid PE+ checksum; is 0x%x, should be 0x%x",
384 po->po_checksum, computed_checksum);
385 }
386 #endif
387
388 if (x->x_len < x->x_headers_len)
389 errx(1, "invalid SizeOfHeaders %d", po->po_size_of_headers);
390 x->x_headers_len = po->po_size_of_headers;
391 //printf("Size of Headers: %d\n", po->po_size_of_headers);
392
393 return (parse_directory(x, off + sizeof(*po),
394 po->po_number_of_rva_and_sizes, number_of_sections));
395 }
396
397 static void
parse_optional_32(struct executable * x,off_t off,int number_of_sections)398 parse_optional_32(struct executable *x, off_t off, int number_of_sections)
399 {
400 #if 0
401 uint32_t computed_checksum;
402 #endif
403 const struct pe_optional_header_32 *po;
404
405 range_check(x, off, sizeof(*po), "PE Optional Header");
406
407 po = (struct pe_optional_header_32 *)(x->x_buf + off);
408 switch (po->po_subsystem) {
409 case PE_OPTIONAL_SUBSYSTEM_EFI_APPLICATION:
410 case PE_OPTIONAL_SUBSYSTEM_EFI_BOOT:
411 case PE_OPTIONAL_SUBSYSTEM_EFI_RUNTIME:
412 break;
413 default:
414 errx(1, "wrong PE Optional Header subsystem 0x%x",
415 po->po_subsystem);
416 }
417
418 #if 0
419 printf("subsystem %d, checksum 0x%x, %d data directories\n",
420 po->po_subsystem, po->po_checksum, po->po_number_of_rva_and_sizes);
421 #endif
422
423 x->x_checksum_off = off +
424 offsetof(struct pe_optional_header_32, po_checksum);
425 x->x_checksum_len = sizeof(po->po_checksum);
426 #if 0
427 printf("checksum at offset %zd, len %zd\n",
428 x->x_checksum_off, x->x_checksum_len);
429
430 computed_checksum = compute_checksum(x);
431 if (computed_checksum != po->po_checksum) {
432 warnx("invalid PE checksum; is 0x%x, should be 0x%x",
433 po->po_checksum, computed_checksum);
434 }
435 #endif
436
437 if (x->x_len < x->x_headers_len)
438 errx(1, "invalid SizeOfHeaders %d", po->po_size_of_headers);
439 x->x_headers_len = po->po_size_of_headers;
440 //printf("Size of Headers: %d\n", po->po_size_of_headers);
441
442 return (parse_directory(x, off + sizeof(*po),
443 po->po_number_of_rva_and_sizes, number_of_sections));
444 }
445
446 static void
parse_optional(struct executable * x,off_t off,int number_of_sections)447 parse_optional(struct executable *x, off_t off, int number_of_sections)
448 {
449 const struct pe_optional_header_32 *po;
450
451 //printf("Optional header offset %zd\n", off);
452
453 range_check(x, off, sizeof(*po), "PE Optional Header");
454
455 po = (struct pe_optional_header_32 *)(x->x_buf + off);
456
457 switch (po->po_magic) {
458 case PE_OPTIONAL_MAGIC_32:
459 return (parse_optional_32(x, off, number_of_sections));
460 case PE_OPTIONAL_MAGIC_32_PLUS:
461 return (parse_optional_32_plus(x, off, number_of_sections));
462 default:
463 errx(1, "wrong PE Optional Header magic 0x%x", po->po_magic);
464 }
465 }
466
467 static void
parse_pe(struct executable * x,off_t off)468 parse_pe(struct executable *x, off_t off)
469 {
470 const struct pe_header *pe;
471
472 //printf("PE offset %zd, PE size %zd\n", off, sizeof(*pe));
473
474 range_check(x, off, sizeof(*pe), "PE header");
475
476 pe = (struct pe_header *)(x->x_buf + off);
477 if (pe->pe_signature != PE_SIGNATURE)
478 errx(1, "wrong PE signature 0x%x", pe->pe_signature);
479
480 //printf("Number of sections: %d\n", pe->pe_coff.coff_number_of_sections);
481
482 parse_optional(x, off + sizeof(*pe),
483 pe->pe_coff.coff_number_of_sections);
484 }
485
486 void
parse(struct executable * x)487 parse(struct executable *x)
488 {
489 const struct mz_header *mz;
490
491 range_check(x, 0, sizeof(*mz), "MZ header");
492
493 mz = (struct mz_header *)x->x_buf;
494 if (mz->mz_signature[0] != 'M' || mz->mz_signature[1] != 'Z')
495 errx(1, "MZ header not found");
496
497 return (parse_pe(x, mz->mz_lfanew));
498 }
499
500 static off_t
append(struct executable * x,void * ptr,size_t len,size_t aligment)501 append(struct executable *x, void *ptr, size_t len, size_t aligment)
502 {
503 off_t off;
504
505 off = x->x_len;
506 x->x_buf = realloc(x->x_buf, x->x_len + len + aligment);
507 if (x->x_buf == NULL)
508 err(1, "realloc");
509 memcpy(x->x_buf + x->x_len, ptr, len);
510 memset(x->x_buf + x->x_len + len, 0, aligment);
511 x->x_len += len + aligment;
512
513 return (off);
514 }
515
516 void
update(struct executable * x)517 update(struct executable *x)
518 {
519 uint32_t checksum;
520 struct pe_certificate *pc;
521 struct pe_directory_entry pde;
522 size_t pc_len;
523 size_t pc_aligment;
524 off_t pc_off;
525
526 pc_len = sizeof(*pc) + x->x_signature_len;
527 pc = calloc(1, pc_len);
528 if (pc == NULL)
529 err(1, "calloc");
530
531 if (pc_len % PE_ALIGMENT_SIZE > 0)
532 pc_aligment = PE_ALIGMENT_SIZE - (pc_len % PE_ALIGMENT_SIZE);
533 else
534 pc_aligment = 0;
535
536 #if 0
537 /*
538 * Note that pc_len is the length of pc_certificate,
539 * not the whole structure.
540 *
541 * XXX: That's what the spec says - but it breaks at least
542 * sbverify and "pesign -S", so the spec is probably wrong.
543 */
544 pc->pc_len = x->x_signature_len;
545 #else
546 pc->pc_len = pc_len;
547 #endif
548 pc->pc_revision = PE_CERTIFICATE_REVISION;
549 pc->pc_type = PE_CERTIFICATE_TYPE;
550 memcpy(&pc->pc_signature, x->x_signature, x->x_signature_len);
551
552 pc_off = append(x, pc, pc_len, pc_aligment);
553 #if 0
554 printf("added signature chunk at offset %zd, len %zd\n",
555 pc_off, pc_len);
556 #endif
557
558 free(pc);
559
560 pde.pde_rva = pc_off;
561 pde.pde_size = pc_len + pc_aligment;
562 memcpy(x->x_buf + x->x_certificate_entry_off, &pde, sizeof(pde));
563
564 checksum = compute_checksum(x);
565 assert(sizeof(checksum) == x->x_checksum_len);
566 memcpy(x->x_buf + x->x_checksum_off, &checksum, sizeof(checksum));
567 #if 0
568 printf("new checksum 0x%x\n", checksum);
569 #endif
570 }
571