usr.sbin/uefisign/pe.c

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