OSX/sec/Security/Tool/codesign.c

   1 /*
   2  * Copyright (c) 2008,2010,2013-2014 Apple Inc. All Rights Reserved.
   3  *
   4  * @APPLE_LICENSE_HEADER_START@
   5  *
   6  * This file contains Original Code and/or Modifications of Original Code
   7  * as defined in and that are subject to the Apple Public Source License
   8  * Version 2.0 (the 'License'). You may not use this file except in
   9  * compliance with the License. Please obtain a copy of the License at
  10  * http://www.opensource.apple.com/apsl/ and read it before using this
  11  * file.
  12  *
  13  * The Original Code and all software distributed under the License are
  14  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  15  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  16  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  17  * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
  18  * Please see the License for the specific language governing rights and
  19  * limitations under the License.
  20  *
  21  * @APPLE_LICENSE_HEADER_END@
  22  */
  23
  24 #include <TargetConditionals.h>
  25 #if TARGET_OS_EMBEDDED
  26
  27 #include "SecurityCommands.h"
  28
  29 #include <AssertMacros.h>
  30 #include <mach-o/loader.h>
  31 #include <mach-o/fat.h>
  32 #include <CoreFoundation/CoreFoundation.h>
  33 #include <Security/SecCMS.h>
  34 #include <Security/SecPolicyPriv.h>
  35 #include <CommonCrypto/CommonDigest.h>
  36 #include <CommonCrypto/CommonDigestSPI.h>
  37 #include <utilities/SecCFRelease.h>
  38
  39 /*
  40  * Magic numbers used by Code Signing
  41  */
  42 enum {
  43         CSMAGIC_REQUIREMENT     = 0xfade0c00,           /* single Requirement blob */
  44         CSMAGIC_REQUIREMENTS = 0xfade0c01,              /* Requirements vector (internal requirements) */
  45         CSMAGIC_CODEDIRECTORY = 0xfade0c02,             /* CodeDirectory blob */
  46         CSMAGIC_EMBEDDED_SIGNATURE = 0xfade0cc0, /* embedded form of signature data */
  47         CSMAGIC_DETACHED_SIGNATURE = 0xfade0cc1, /* multi-arch collection of embedded signatures */
  48
  49         CSSLOT_CODEDIRECTORY = 0,                               /* slot index for CodeDirectory */
  50 };
  51
  52
  53 /*
  54  * Structure of an embedded-signature SuperBlob
  55  */
  56 typedef struct __BlobIndex {
  57         uint32_t type;                                  /* type of entry */
  58         uint32_t offset;                                /* offset of entry */
  59 } CS_BlobIndex;
  60
  61 typedef struct __SuperBlob {
  62         uint32_t magic;                                 /* magic number */
  63         uint32_t length;                                /* total length of SuperBlob */
  64         uint32_t count;                                 /* number of index entries following */
  65         CS_BlobIndex index[];                   /* (count) entries */
  66         /* followed by Blobs in no particular order as indicated by offsets in index */
  67 } CS_SuperBlob;
  68
  69
  70 /*
  71  * C form of a CodeDirectory.
  72  */
  73 typedef struct __CodeDirectory {
  74         uint32_t magic;                                 /* magic number (CSMAGIC_CODEDIRECTORY) */
  75         uint32_t length;                                /* total length of CodeDirectory blob */
  76         uint32_t version;                               /* compatibility version */
  77         uint32_t flags;                                 /* setup and mode flags */
  78         uint32_t hashOffset;                    /* offset of hash slot element at index zero */
  79         uint32_t identOffset;                   /* offset of identifier string */
  80         uint32_t nSpecialSlots;                 /* number of special hash slots */
  81         uint32_t nCodeSlots;                    /* number of ordinary (code) hash slots */
  82         uint32_t codeLimit;                             /* limit to main image signature range */
  83         uint8_t hashSize;                               /* size of each hash in bytes */
  84         uint8_t hashType;                               /* type of hash (cdHashType* constants) */
  85         uint8_t spare1;                                 /* unused (must be zero) */
  86         uint8_t pageSize;                               /* log2(page size in bytes); 0 => infinite */
  87         uint32_t spare2;                                /* unused (must be zero) */
  88         /* followed by dynamic content as located by offset fields above */
  89 } CS_CodeDirectory;
  90
  91
  92         //assert(page < ntohl(cd->nCodeSlots));
  93         //return base + ntohl(cd->hashOffset) + page * 20;
  94
  95 #if 0
  96 static void debug_data(uint8_t *data, size_t length)
  97 {
  98     uint32_t i, j;
  99     for (i = 0; i < length; i+=16) {
 100         fprintf(stderr, "%p   ", (void*)(data+i));
 101         for (j = 0; (j < 16) && (j+i < length); j++) {
 102             uint8_t byte = *(uint8_t*)(data+i+j);
 103             fprintf(stderr, "%.02x %c|", byte, isprint(byte) ? byte : '?');
 104         }
 105         fprintf(stderr, "\n");
 106     }
 107 }
 108
 109 static void write_data(const char *path, uint8_t *data, size_t length)
 110 {
 111     int fd = open(path, O_RDWR|O_TRUNC|O_CREAT, 0644);
 112     require(fd>0, out);
 113     write(fd, data, length);
 114     close(fd);
 115 out:
 116     return;
 117 }
 118 #endif
 119
 120 static void fprint_digest(FILE *file, unsigned char *digest, size_t length) {
 121     size_t ix;
 122     for (ix = 0; ix < length; ++ix) {
 123         fprintf(file, "%02x", digest[ix]);
 124     }
 125 }
 126
 127 static CFMutableDictionaryRef lc_code_sig(uint8_t *lc_code_signature, size_t lc_code_signature_len)
 128 {
 129     CFMutableDictionaryRef code_signature =
 130         CFDictionaryCreateMutable(kCFAllocatorDefault, 0,
 131                 &kCFTypeDictionaryKeyCallBacks,
 132                 &kCFTypeDictionaryValueCallBacks);
 133     require(code_signature, out);
 134
 135     CS_SuperBlob *sb = (CS_SuperBlob*)lc_code_signature;
 136     require(ntohl(sb->magic) == CSMAGIC_EMBEDDED_SIGNATURE, out);
 137     uint32_t count;
 138     for (count = 0; count < ntohl(sb->count); count++) {
 139         //uint32_t type = ntohl(sb->index[count].type);
 140         uint32_t offset = ntohl(sb->index[count].offset);
 141         uint8_t *bytes = lc_code_signature + offset;
 142         //fprintf(stderr, "blob[%d]: (type: 0x%.08x, offset: %p)\n", count, type, (void*)offset);
 143         uint32_t magic = ntohl(*(uint32_t*)bytes);
 144         uint32_t length = ntohl(*(uint32_t*)(bytes+4));
 145         //fprintf(stderr, "    magic: 0x%.08x length: %d\n", magic, length);
 146         switch(magic) {
 147             case 0xfade0c01: //write_data("requirements", bytes, length);
 148                 break;
 149             case 0xfade0c02: //write_data("codedir", bytes, length);
 150             {
 151                 const CS_CodeDirectory *cd = (const CS_CodeDirectory *)bytes;
 152                 CFDataRef codedir = CFDataCreate(kCFAllocatorDefault, bytes, length);
 153                 require(codedir, out);
 154                 CFDictionarySetValue(code_signature, CFSTR("CodeDirectory"), codedir);
 155                 CFRelease(codedir);
 156                 require_string(ntohl(cd->version) >= 0x20001, out, "incompatible version");
 157                 require_string(ntohl(cd->version) <= 0x2F000, out, "incompatible version");
 158                 require_string(cd->hashSize == 20, out, "unexpected hash size");
 159                 require_string(cd->hashType == 1, out, "unexpected hash type");
 160
 161                 uint32_t hash_offset = ntohl(cd->hashOffset);
 162                 uint32_t entitlement_slot = 5;
 163
 164                 if (ntohl(cd->nSpecialSlots) >= entitlement_slot) {
 165                     CFDataRef message = CFDataCreate(kCFAllocatorDefault, bytes+hash_offset-entitlement_slot*cd->hashSize, cd->hashSize);
 166                     require(message, out);
 167                     CFDictionarySetValue(code_signature, CFSTR("EntitlementsCDHash"), message);
 168                     CFRelease(message);
 169                 } else
 170                     fprintf(stderr, "no entitlements slot yet\n");
 171             }
 172                 break;
 173             case 0xfade0b01:  //write_data("signed", lc_code_signature, bytes-lc_code_signature);
 174                 if (length != 8) {
 175                     CFDataRef message = CFDataCreate(kCFAllocatorDefault, bytes+8, length-8);
 176                     require(message, out);
 177                     CFDictionarySetValue(code_signature, CFSTR("SignedData"), message);
 178                     CFRelease(message);
 179                 }
 180                 break;
 181             case 0xfade7171:
 182             {
 183                 unsigned char digest[CC_SHA1_DIGEST_LENGTH];
 184                 CCDigest(kCCDigestSHA1, bytes, length, digest);
 185
 186                 CFDataRef message = CFDataCreate(kCFAllocatorDefault, digest, sizeof(digest));
 187                 require(message, out);
 188                 CFDictionarySetValue(code_signature, CFSTR("EntitlementsHash"), message);
 189                 CFRelease(message);
 190                 message = CFDataCreate(kCFAllocatorDefault, bytes+8, length-8);
 191                 require(message, out);
 192                 CFDictionarySetValue(code_signature, CFSTR("Entitlements"), message);
 193                 CFRelease(message);
 194                 break;
 195             }
 196             default:
 197                 fprintf(stderr, "Skipping block with magic: 0x%x\n", magic);
 198                 break;
 199         }
 200     }
 201     return code_signature;
 202 out:
 203     if (code_signature) CFRelease(code_signature);
 204     return NULL;
 205 }
 206
 207 static FILE *
 208 open_bundle(const char * path, const char * mode)
 209 {
 210     char full_path[1024] = {};
 211     CFStringRef path_cfstring = NULL;
 212     CFURLRef path_url = NULL;
 213     CFBundleRef bundle = NULL;
 214     CFURLRef exec = NULL;
 215
 216     path_cfstring = CFStringCreateWithFileSystemRepresentation(kCFAllocatorDefault, path);
 217     require_quiet(path_cfstring, out);
 218     path_url = CFURLCreateWithFileSystemPath(kCFAllocatorDefault, path_cfstring, kCFURLPOSIXPathStyle, true);
 219     require_quiet(path_url, out);
 220         bundle =  CFBundleCreate(kCFAllocatorDefault, path_url);
 221     require_quiet(bundle, out);
 222     exec = CFBundleCopyExecutableURL(bundle);
 223     require(exec, out);
 224     require(CFURLGetFileSystemRepresentation(exec, true, (uint8_t*)full_path, sizeof(full_path)), out);
 225 out:
 226     CFReleaseSafe(path_cfstring);
 227     CFReleaseSafe(path_url);
 228     CFReleaseSafe(bundle);
 229     CFReleaseSafe(exec);
 230
 231     return fopen(full_path, "r");
 232 }
 233
 234 static CFMutableDictionaryRef load_code_signature(FILE *binary, size_t slice_offset)
 235 {
 236     bool signature_found = false;
 237     CFMutableDictionaryRef result = NULL;
 238     struct load_command lc;
 239     do {
 240         require(1 == fread(&lc, sizeof(lc), 1, binary), out);
 241         if (lc.cmd == LC_CODE_SIGNATURE) {
 242             struct { uint32_t offset; uint32_t size; } sig;
 243             require(1 == fread(&sig, sizeof(sig), 1, binary), out);
 244             require_noerr(fseek(binary, slice_offset+sig.offset, SEEK_SET), out);
 245             size_t length = sig.size;
 246             uint8_t *data = malloc(length);
 247             require(length && data, out);
 248             require(1 == fread(data, length, 1, binary), out);
 249             signature_found = true;
 250             result = lc_code_sig(data, length);
 251             free(data);
 252             break;
 253         }
 254         require_noerr(fseek(binary, lc.cmdsize-sizeof(lc), SEEK_CUR), out);
 255     } while(lc.cmd || lc.cmdsize); /* count lc */
 256 out:
 257     if (!signature_found)
 258         fprintf(stderr, "No LC_CODE_SIGNATURE segment found\n");
 259     return result;
 260 }
 261
 262 static CF_RETURNS_RETAINED CFArrayRef load_code_signatures(const char *path)
 263 {
 264     bool fully_parsed_binary = false;
 265     CFMutableDictionaryRef result = NULL;
 266     CFMutableArrayRef results = CFArrayCreateMutable(kCFAllocatorDefault, 0, &kCFTypeArrayCallBacks);
 267
 268     FILE *binary = open_bundle(path, "r");
 269     if (!binary) binary = fopen(path, "r");
 270     require(binary, out);
 271
 272     struct mach_header header;
 273     require(1 == fread(&header, sizeof(header), 1, binary), out);
 274     if ((header.magic == MH_MAGIC) || (header.magic == MH_MAGIC_64)) {
 275         if (header.magic == MH_MAGIC_64)
 276                 fseek(binary, sizeof(struct mach_header_64) - sizeof(struct mach_header), SEEK_CUR);
 277         result = load_code_signature(binary, 0 /*non fat*/);
 278         require(result, out);
 279         CFStringRef type = CFStringCreateWithFormat(kCFAllocatorDefault, NULL, CFSTR("CPU type: (%d,%d)"), header.cputype, header.cpusubtype);
 280         CFDictionarySetValue(result, CFSTR("ARCH"), type);
 281         CFRelease(type);
 282         CFArrayAppendValue(results, result);
 283     }
 284     else
 285     {
 286         struct fat_header fat;
 287         require(!fseek(binary, 0L, SEEK_SET), out);
 288         require(1 == fread(&fat, sizeof(fat), 1, binary), out);
 289         require(ntohl(fat.magic) == FAT_MAGIC, out);
 290         uint32_t slice, slices = ntohl(fat.nfat_arch);
 291         struct fat_arch *archs = calloc(slices, sizeof(struct fat_arch));
 292         require(slices == fread(archs, sizeof(struct fat_arch), slices, binary), out);
 293         for (slice = 0; slice < slices; slice++) {
 294             uint32_t slice_offset = ntohl(archs[slice].offset);
 295             require(!fseek(binary, slice_offset, SEEK_SET), out);
 296             require(1 == fread(&header, sizeof(header), 1, binary), out);
 297             require((header.magic == MH_MAGIC) || (header.magic == MH_MAGIC_64), out);
 298             if (header.magic == MH_MAGIC_64)
 299                     fseek(binary, sizeof(struct mach_header_64) - sizeof(struct mach_header), SEEK_CUR);
 300             result = load_code_signature(binary, slice_offset);
 301             require(result, out);
 302             CFStringRef type = CFStringCreateWithFormat(kCFAllocatorDefault, NULL, CFSTR("CPU type: (%d,%d)"), header.cputype, header.cpusubtype);
 303             CFDictionarySetValue(result, CFSTR("ARCH"), type);
 304             CFRelease(type);
 305             CFArrayAppendValue(results, result);
 306             CFRelease(result);
 307         }
 308     }
 309     fully_parsed_binary = true;
 310 out:
 311     if (!fully_parsed_binary) {
 312         if (results) {
 313             CFRelease(results);
 314             results = NULL;
 315         }
 316     }
 317     if (binary)
 318         fclose(binary);
 319     return results;
 320 }
 321
 322
 323 extern int codesign_util(int argc, char * const *argv)
 324 {
 325     int             result = 1, verbose = 0;
 326     char            ch;
 327
 328     while ((ch = getopt(argc, argv, "v")) != -1)
 329     {
 330         switch (ch)
 331         {
 332         case 'v':
 333             verbose++;
 334             break;
 335         default:
 336             return 2; /* Trigger usage message. */
 337         }
 338     }
 339
 340         argc -= optind;
 341         argv += optind;
 342
 343     if (argc != 1)
 344         return 2; /* Trigger usage message. */
 345
 346     CFArrayRef sigs = load_code_signatures(argv[0]);
 347     require(sigs, out);
 348
 349     if (verbose >= 2)
 350         CFShow(sigs);
 351
 352     CFIndex i, count = CFArrayGetCount(sigs);
 353
 354     for (i = 0; i < count; i++) {
 355         CFDictionaryRef signature = CFArrayGetValueAtIndex(sigs, i);
 356
 357         CFDataRef code_dir = CFDictionaryGetValue(signature, CFSTR("CodeDirectory"));
 358         const CS_CodeDirectory *cd = (CS_CodeDirectory *)CFDataGetBytePtr(code_dir);
 359
 360         CFDataRef signed_data = CFDictionaryGetValue(signature, CFSTR("SignedData"));
 361
 362         CFDataRef entitlements = CFDictionaryGetValue(signature, CFSTR("Entitlements"));
 363         CFDataRef entitlements_cd_hash = CFDictionaryGetValue(signature, CFSTR("EntitlementsCDHash"));
 364         CFDataRef entitlements_hash = CFDictionaryGetValue(signature, CFSTR("EntitlementsHash"));
 365
 366         CFStringRef arch = CFDictionaryGetValue(signature, CFSTR("ARCH"));
 367
 368         CFShow(arch);
 369
 370         SecPolicyRef policy = SecPolicyCreateiPhoneApplicationSigning();
 371
 372         if (signed_data) {
 373             if (SecCMSVerify(signed_data, code_dir, policy, NULL, NULL)) {
 374                 fprintf(stderr, "Failed to verify signature\n");
 375                 result = -1;
 376             } else
 377                 fprintf(stderr, "Signature ok\n");
 378
 379         } else
 380             fprintf(stderr, "Ad-hoc signed binary\n");
 381
 382         if (entitlements_cd_hash) {
 383             if (entitlements_hash && entitlements_cd_hash && CFEqual(entitlements_hash, entitlements_cd_hash))
 384                 fprintf(stderr, "Entitlements ok\n");
 385             else
 386                 fprintf(stderr, "Entitlements modified\n");
 387         }
 388
 389         if (verbose >= 2) {
 390             fprintf(stderr, "magic: 0x%x length: %u(%lu)\n", ntohl(cd->magic), ntohl(cd->length), CFDataGetLength(code_dir));
 391             fprintf(stderr, "code directory version/flags: 0x%x/0x%x special/code hash slots: %u/%u\n"
 392                 "codelimit: %u hash size/type: %u/%u hash/ident offset: %u/%u\n",
 393                 ntohl(cd->version), ntohl(cd->flags), ntohl(cd->nSpecialSlots), ntohl(cd->nCodeSlots),
 394                 ntohl(cd->codeLimit), cd->hashSize, cd->hashType, ntohl(cd->hashOffset), ntohl(cd->identOffset));
 395             fprintf(stderr, "ident: '%s'\n", CFDataGetBytePtr(code_dir) + ntohl(cd->identOffset));
 396
 397             uint32_t ix;
 398             uint8_t *hashes = (uint8_t *)CFDataGetBytePtr(code_dir) + ntohl(cd->hashOffset);
 399             for (ix = 0; ix < ntohl(cd->nSpecialSlots); ++ix) {
 400                 fprint_digest(stderr, hashes, cd->hashSize);
 401                 fprintf(stderr, "\n");
 402                 hashes += cd->hashSize;
 403             }
 404         }
 405
 406         if (verbose >= 1) {
 407             if (entitlements)
 408                 fprintf(stderr, "Entitlements\n%.*s", (int)CFDataGetLength(entitlements)-8, CFDataGetBytePtr(entitlements)+8);
 409         }
 410
 411         if (verbose >= 2) {
 412             if (entitlements_hash) {
 413                 fprintf(stderr, "digest: ");
 414                 fprint_digest(stderr, (uint8_t *)CFDataGetBytePtr(entitlements_hash), CC_SHA1_DIGEST_LENGTH);
 415                 fprintf(stderr, "\n");
 416             }
 417         }
 418         CFReleaseNull(policy);
 419     }
 420
 421     CFReleaseSafe(sigs);
 422
 423     return result;
 424 out:
 425     return -1;
 426 }
 427
 428 #endif // TARGET_OS_EMBEDDED