Randall Spangler | 786acda | 2014-05-22 13:27:07 -0700 | [diff] [blame] | 1 | /* Copyright (c) 2014 The Chromium OS Authors. All rights reserved. |
| 2 | * Use of this source code is governed by a BSD-style license that can be |
| 3 | * found in the LICENSE file. |
| 4 | * |
| 5 | * Common functions between firmware and kernel verified boot. |
| 6 | * (Firmware portion) |
| 7 | */ |
| 8 | |
| 9 | #include "2sysincludes.h" |
| 10 | #include "2common.h" |
Randall Spangler | 7141d73 | 2014-05-15 15:34:54 -0700 | [diff] [blame] | 11 | #include "2rsa.h" |
| 12 | #include "2sha.h" |
Randall Spangler | 786acda | 2014-05-22 13:27:07 -0700 | [diff] [blame] | 13 | |
| 14 | int vb2_align(uint8_t **ptr, uint32_t *size, uint32_t align, uint32_t want_size) |
| 15 | { |
| 16 | uintptr_t p = (uintptr_t)*ptr; |
| 17 | uintptr_t offs = p & (align - 1); |
| 18 | |
| 19 | if (offs) { |
| 20 | offs = align - offs; |
| 21 | |
| 22 | if (*size < offs) |
Randall Spangler | 2145721 | 2014-06-06 09:30:14 -0700 | [diff] [blame^] | 23 | return VB2_ERROR_ALIGN_BIGGER_THAN_SIZE; |
Randall Spangler | 786acda | 2014-05-22 13:27:07 -0700 | [diff] [blame] | 24 | |
| 25 | *ptr += offs; |
| 26 | *size -= offs; |
| 27 | } |
| 28 | |
| 29 | if (*size < want_size) |
Randall Spangler | 2145721 | 2014-06-06 09:30:14 -0700 | [diff] [blame^] | 30 | return VB2_ERROR_ALIGN_SIZE; |
Randall Spangler | 786acda | 2014-05-22 13:27:07 -0700 | [diff] [blame] | 31 | |
| 32 | return VB2_SUCCESS; |
| 33 | } |
| 34 | |
| 35 | void vb2_workbuf_init(struct vb2_workbuf *wb, uint8_t *buf, uint32_t size) |
| 36 | { |
| 37 | wb->buf = buf; |
| 38 | wb->size = size; |
| 39 | |
| 40 | /* Align the buffer so allocations will be aligned */ |
| 41 | if (vb2_align(&wb->buf, &wb->size, VB2_WORKBUF_ALIGN, 0)) |
| 42 | wb->size = 0; |
| 43 | } |
| 44 | |
| 45 | /** |
| 46 | * Round up a number to a multiple of VB2_WORKBUF_ALIGN |
| 47 | * |
| 48 | * @param v Number to round up |
| 49 | * @return The number, rounded up. |
| 50 | */ |
| 51 | static __inline uint32_t wb_round_up(uint32_t v) |
| 52 | { |
| 53 | return (v + VB2_WORKBUF_ALIGN - 1) & ~(VB2_WORKBUF_ALIGN - 1); |
| 54 | } |
| 55 | |
| 56 | void *vb2_workbuf_alloc(struct vb2_workbuf *wb, uint32_t size) |
| 57 | { |
| 58 | uint8_t *ptr = wb->buf; |
| 59 | |
| 60 | /* Round up size to work buffer alignment */ |
| 61 | size = wb_round_up(size); |
| 62 | |
| 63 | if (size > wb->size) |
| 64 | return NULL; |
| 65 | |
| 66 | wb->buf += size; |
| 67 | wb->size -= size; |
| 68 | |
| 69 | return ptr; |
| 70 | } |
| 71 | |
| 72 | void *vb2_workbuf_realloc(struct vb2_workbuf *wb, |
| 73 | uint32_t oldsize, |
| 74 | uint32_t newsize) |
| 75 | { |
| 76 | /* |
| 77 | * Just free and allocate to update the size. No need to move/copy |
| 78 | * memory, since the new pointer is guaranteed to be the same as the |
| 79 | * old one. The new allocation can fail, if the new size is too big. |
| 80 | */ |
| 81 | vb2_workbuf_free(wb, oldsize); |
| 82 | return vb2_workbuf_alloc(wb, newsize); |
| 83 | } |
| 84 | |
| 85 | void vb2_workbuf_free(struct vb2_workbuf *wb, uint32_t size) |
| 86 | { |
| 87 | /* Round up size to work buffer alignment */ |
| 88 | size = wb_round_up(size); |
| 89 | |
| 90 | wb->buf -= size; |
| 91 | wb->size += size; |
| 92 | } |
| 93 | |
Randall Spangler | 7141d73 | 2014-05-15 15:34:54 -0700 | [diff] [blame] | 94 | const uint8_t *vb2_packed_key_data(const struct vb2_packed_key *key) |
| 95 | { |
| 96 | return (const uint8_t *)key + key->key_offset; |
| 97 | } |
| 98 | |
| 99 | uint8_t *vb2_signature_data(struct vb2_signature *sig) |
| 100 | { |
| 101 | return (uint8_t *)sig + sig->sig_offset; |
| 102 | } |
| 103 | |
Randall Spangler | 786acda | 2014-05-22 13:27:07 -0700 | [diff] [blame] | 104 | ptrdiff_t vb2_offset_of(const void *base, const void *ptr) |
| 105 | { |
| 106 | return (uintptr_t)ptr - (uintptr_t)base; |
| 107 | } |
Randall Spangler | 7141d73 | 2014-05-15 15:34:54 -0700 | [diff] [blame] | 108 | |
Randall Spangler | 2145721 | 2014-06-06 09:30:14 -0700 | [diff] [blame^] | 109 | int vb2_verify_member_inside(const void *parent, size_t parent_size, |
| 110 | const void *member, size_t member_size, |
| 111 | ptrdiff_t member_data_offset, |
| 112 | size_t member_data_size) |
Randall Spangler | 7141d73 | 2014-05-15 15:34:54 -0700 | [diff] [blame] | 113 | { |
| 114 | const size_t psize = (size_t)parent_size; |
| 115 | const uintptr_t parent_end = (uintptr_t)parent + parent_size; |
| 116 | const ptrdiff_t member_offs = vb2_offset_of(parent, member); |
| 117 | const ptrdiff_t member_end_offs = member_offs + member_size; |
| 118 | const ptrdiff_t data_offs = member_offs + member_data_offset; |
| 119 | const ptrdiff_t data_end_offs = data_offs + member_data_size; |
| 120 | |
| 121 | /* Make sure parent doesn't wrap */ |
| 122 | if (parent_end < (uintptr_t)parent) |
Randall Spangler | 2145721 | 2014-06-06 09:30:14 -0700 | [diff] [blame^] | 123 | return VB2_ERROR_INSIDE_PARENT_WRAPS; |
Randall Spangler | 7141d73 | 2014-05-15 15:34:54 -0700 | [diff] [blame] | 124 | |
| 125 | /* |
| 126 | * Make sure the member is fully contained in the parent and doesn't |
| 127 | * wrap. Use >, not >=, since member_size = 0 is possible. |
| 128 | */ |
| 129 | if (member_end_offs < member_offs) |
Randall Spangler | 2145721 | 2014-06-06 09:30:14 -0700 | [diff] [blame^] | 130 | return VB2_ERROR_INSIDE_MEMBER_WRAPS; |
| 131 | if (member_offs < 0 || member_offs > psize || member_end_offs > psize) |
| 132 | return VB2_ERROR_INSIDE_MEMBER_OUTSIDE; |
Randall Spangler | 7141d73 | 2014-05-15 15:34:54 -0700 | [diff] [blame] | 133 | |
| 134 | /* Make sure parent fully contains member data */ |
| 135 | if (data_end_offs < data_offs) |
Randall Spangler | 2145721 | 2014-06-06 09:30:14 -0700 | [diff] [blame^] | 136 | return VB2_ERROR_INSIDE_DATA_WRAPS; |
| 137 | if (data_offs < 0 || data_offs > psize || data_end_offs > psize) |
| 138 | return VB2_ERROR_INSIDE_DATA_OUTSIDE; |
Randall Spangler | 7141d73 | 2014-05-15 15:34:54 -0700 | [diff] [blame] | 139 | |
| 140 | return VB2_SUCCESS; |
| 141 | } |
| 142 | |
| 143 | int vb2_verify_signature_inside(const void *parent, |
| 144 | uint32_t parent_size, |
| 145 | const struct vb2_signature *sig) |
| 146 | { |
| 147 | return vb2_verify_member_inside(parent, parent_size, |
| 148 | sig, sizeof(*sig), |
| 149 | sig->sig_offset, sig->sig_size); |
| 150 | } |
| 151 | |
| 152 | int vb2_verify_packed_key_inside(const void *parent, |
| 153 | uint32_t parent_size, |
| 154 | const struct vb2_packed_key *key) |
| 155 | { |
| 156 | return vb2_verify_member_inside(parent, parent_size, |
| 157 | key, sizeof(*key), |
| 158 | key->key_offset, key->key_size); |
| 159 | } |
| 160 | |
| 161 | int vb2_unpack_key(struct vb2_public_key *key, |
| 162 | const uint8_t *buf, |
| 163 | uint32_t size) |
| 164 | { |
| 165 | const struct vb2_packed_key *packed_key = |
| 166 | (const struct vb2_packed_key *)buf; |
| 167 | const uint32_t *buf32; |
| 168 | uint32_t expected_key_size; |
| 169 | int rv; |
| 170 | |
| 171 | /* Make sure passed buffer is big enough for the packed key */ |
| 172 | rv = vb2_verify_packed_key_inside(buf, size, packed_key); |
| 173 | if (rv) |
| 174 | return rv; |
| 175 | |
| 176 | if (packed_key->algorithm >= VB2_ALG_COUNT) { |
| 177 | VB2_DEBUG("Invalid algorithm.\n"); |
| 178 | return VB2_ERROR_BAD_ALGORITHM; |
| 179 | } |
| 180 | |
| 181 | expected_key_size = vb2_packed_key_size(packed_key->algorithm); |
| 182 | if (!expected_key_size || expected_key_size != packed_key->key_size) { |
| 183 | VB2_DEBUG("Wrong key size for algorithm\n"); |
| 184 | return VB2_ERROR_BAD_KEY; |
| 185 | } |
| 186 | |
| 187 | /* Make sure source buffer is 32-bit aligned */ |
| 188 | buf32 = (const uint32_t *)vb2_packed_key_data(packed_key); |
| 189 | if (!vb_aligned(buf32, sizeof(uint32_t))) |
| 190 | return VB2_ERROR_BUFFER_UNALIGNED; |
| 191 | |
| 192 | /* Sanity check key array size */ |
| 193 | key->arrsize = buf32[0]; |
| 194 | if (key->arrsize * sizeof(uint32_t) != |
| 195 | vb2_rsa_sig_size(packed_key->algorithm)) |
| 196 | return VB2_ERROR_BAD_KEY; |
| 197 | |
| 198 | key->n0inv = buf32[1]; |
| 199 | |
| 200 | /* Arrays point inside the key data */ |
| 201 | key->n = buf32 + 2; |
| 202 | key->rr = buf32 + 2 + key->arrsize; |
| 203 | |
| 204 | key->algorithm = packed_key->algorithm; |
| 205 | |
| 206 | return VB2_SUCCESS; |
| 207 | } |
| 208 | |
| 209 | int vb2_verify_data(const uint8_t *data, |
| 210 | uint32_t size, |
| 211 | struct vb2_signature *sig, |
| 212 | const struct vb2_public_key *key, |
| 213 | struct vb2_workbuf *wb) |
| 214 | { |
| 215 | struct vb2_workbuf wblocal = *wb; |
| 216 | struct vb2_digest_context *dc; |
| 217 | uint8_t *digest; |
| 218 | uint32_t digest_size; |
| 219 | int rv; |
| 220 | |
| 221 | if (key->algorithm >= VB2_ALG_COUNT) |
| 222 | return VB2_ERROR_BAD_ALGORITHM; |
| 223 | |
| 224 | if (sig->sig_size != vb2_rsa_sig_size(key->algorithm)) { |
| 225 | VB2_DEBUG("Wrong data signature size for algorithm, " |
| 226 | "sig_size=%d, expected %d for algorithm %d.\n", |
| 227 | (int)sig->sig_size, vb2_rsa_sig_size(key->algorithm), |
| 228 | key->algorithm); |
| 229 | return VB2_ERROR_BAD_SIGNATURE; |
| 230 | } |
| 231 | |
| 232 | if (sig->data_size > size) { |
| 233 | VB2_DEBUG("Data buffer smaller than length of signed data.\n"); |
| 234 | return VB2_ERROR_UNKNOWN; |
| 235 | } |
| 236 | |
| 237 | /* Digest goes at start of work buffer */ |
| 238 | digest_size = vb2_digest_size(key->algorithm); |
| 239 | digest = vb2_workbuf_alloc(&wblocal, digest_size); |
| 240 | if (!digest) |
| 241 | return VB2_ERROR_WORKBUF_TOO_SMALL; |
| 242 | |
| 243 | /* Hashing requires temp space for the context */ |
| 244 | dc = vb2_workbuf_alloc(&wblocal, sizeof(*dc)); |
| 245 | if (!dc) |
| 246 | return VB2_ERROR_WORKBUF_TOO_SMALL; |
| 247 | |
| 248 | rv = vb2_digest_init(dc, key->algorithm); |
| 249 | if (rv) |
| 250 | return rv; |
| 251 | |
| 252 | rv = vb2_digest_extend(dc, data, sig->data_size); |
| 253 | if (rv) |
| 254 | return rv; |
| 255 | |
| 256 | rv = vb2_digest_finalize(dc, digest, digest_size); |
| 257 | if (rv) |
| 258 | return rv; |
| 259 | |
| 260 | vb2_workbuf_free(&wblocal, sizeof(*dc)); |
| 261 | |
| 262 | return vb2_verify_digest(key, vb2_signature_data(sig), digest, |
| 263 | &wblocal); |
| 264 | } |
| 265 | |
| 266 | int vb2_verify_keyblock(struct vb2_keyblock *block, |
| 267 | uint32_t size, |
| 268 | const struct vb2_public_key *key, |
| 269 | struct vb2_workbuf *wb) |
| 270 | { |
| 271 | struct vb2_signature *sig; |
| 272 | int rv; |
| 273 | |
| 274 | /* Sanity checks before attempting signature of data */ |
| 275 | if(size < sizeof(*block)) { |
| 276 | VB2_DEBUG("Not enough space for key block header.\n"); |
| 277 | return VB2_ERROR_BAD_KEYBLOCK; |
| 278 | } |
| 279 | if (memcmp(block->magic, KEY_BLOCK_MAGIC, KEY_BLOCK_MAGIC_SIZE)) { |
| 280 | VB2_DEBUG("Not a valid verified boot key block.\n"); |
| 281 | return VB2_ERROR_BAD_KEYBLOCK; |
| 282 | } |
| 283 | if (block->header_version_major != KEY_BLOCK_HEADER_VERSION_MAJOR) { |
| 284 | VB2_DEBUG("Incompatible key block header version.\n"); |
| 285 | return VB2_ERROR_BAD_KEYBLOCK; |
| 286 | } |
| 287 | if (size < block->keyblock_size) { |
| 288 | VB2_DEBUG("Not enough data for key block.\n"); |
| 289 | return VB2_ERROR_BAD_KEYBLOCK; |
| 290 | } |
| 291 | |
| 292 | /* Check signature */ |
| 293 | sig = &block->keyblock_signature; |
| 294 | |
| 295 | if (vb2_verify_signature_inside(block, block->keyblock_size, sig)) { |
| 296 | VB2_DEBUG("Key block signature off end of block\n"); |
| 297 | return VB2_ERROR_BAD_KEYBLOCK; |
| 298 | } |
| 299 | |
| 300 | /* Make sure advertised signature data sizes are sane. */ |
| 301 | if (block->keyblock_size < sig->data_size) { |
| 302 | VB2_DEBUG("Signature calculated past end of block\n"); |
| 303 | return VB2_ERROR_BAD_KEYBLOCK; |
| 304 | } |
| 305 | |
| 306 | VB2_DEBUG("Checking key block signature...\n"); |
| 307 | rv = vb2_verify_data((const uint8_t *)block, size, sig, key, wb); |
| 308 | if (rv) { |
| 309 | VB2_DEBUG("Invalid key block signature.\n"); |
| 310 | return VB2_ERROR_BAD_SIGNATURE; |
| 311 | } |
| 312 | |
| 313 | /* Verify we signed enough data */ |
| 314 | if (sig->data_size < sizeof(struct vb2_keyblock)) { |
| 315 | VB2_DEBUG("Didn't sign enough data\n"); |
| 316 | return VB2_ERROR_BAD_KEYBLOCK; |
| 317 | } |
| 318 | |
| 319 | /* Verify data key is inside the block and inside signed data */ |
| 320 | if (vb2_verify_packed_key_inside(block, block->keyblock_size, |
| 321 | &block->data_key)) { |
| 322 | VB2_DEBUG("Data key off end of key block\n"); |
| 323 | return VB2_ERROR_BAD_KEYBLOCK; |
| 324 | } |
| 325 | if (vb2_verify_packed_key_inside(block, sig->data_size, |
| 326 | &block->data_key)) { |
| 327 | VB2_DEBUG("Data key off end of signed data\n"); |
| 328 | return VB2_ERROR_BAD_KEYBLOCK; |
| 329 | } |
| 330 | |
| 331 | /* Success */ |
| 332 | return VB2_SUCCESS; |
| 333 | } |
| 334 | |
| 335 | int vb2_verify_fw_preamble(struct vb2_fw_preamble *preamble, |
| 336 | uint32_t size, |
| 337 | const struct vb2_public_key *key, |
| 338 | struct vb2_workbuf *wb) |
| 339 | { |
| 340 | struct vb2_signature *sig = &preamble->preamble_signature; |
| 341 | |
| 342 | VB2_DEBUG("Verifying preamble.\n"); |
| 343 | |
| 344 | /* Sanity checks before attempting signature of data */ |
| 345 | if(size < EXPECTED_VB2FIRMWAREPREAMBLEHEADER2_1_SIZE) { |
| 346 | VB2_DEBUG("Not enough data for preamble header 2.1.\n"); |
| 347 | return VB2_ERROR_BAD_PREAMBLE; |
| 348 | } |
| 349 | if (preamble->header_version_major != |
| 350 | FIRMWARE_PREAMBLE_HEADER_VERSION_MAJOR) { |
| 351 | VB2_DEBUG("Incompatible firmware preamble header version.\n"); |
| 352 | return VB2_ERROR_BAD_PREAMBLE; |
| 353 | } |
| 354 | |
| 355 | if (preamble->header_version_minor < 1) { |
| 356 | VB2_DEBUG("Only preamble header 2.1+ supported\n"); |
| 357 | return VB2_ERROR_BAD_PREAMBLE; |
| 358 | } |
| 359 | |
| 360 | if (size < preamble->preamble_size) { |
| 361 | VB2_DEBUG("Not enough data for preamble.\n"); |
| 362 | return VB2_ERROR_BAD_PREAMBLE; |
| 363 | } |
| 364 | |
| 365 | /* Check signature */ |
| 366 | if (vb2_verify_signature_inside(preamble, preamble->preamble_size, |
| 367 | sig)) { |
| 368 | VB2_DEBUG("Preamble signature off end of preamble\n"); |
| 369 | return VB2_ERROR_BAD_PREAMBLE; |
| 370 | } |
| 371 | |
| 372 | /* Make sure advertised signature data sizes are sane. */ |
| 373 | if (preamble->preamble_size < sig->data_size) { |
| 374 | VB2_DEBUG("Signature calculated past end of the block\n"); |
| 375 | return VB2_ERROR_BAD_PREAMBLE; |
| 376 | } |
| 377 | |
| 378 | if (vb2_verify_data((const uint8_t *)preamble, size, sig, key, wb)) { |
| 379 | VB2_DEBUG("Preamble signature validation failed\n"); |
| 380 | return VB2_ERROR_BAD_SIGNATURE; |
| 381 | } |
| 382 | |
| 383 | /* Verify we signed enough data */ |
| 384 | if (sig->data_size < sizeof(struct vb2_fw_preamble)) { |
| 385 | VB2_DEBUG("Didn't sign enough data\n"); |
| 386 | return VB2_ERROR_BAD_PREAMBLE; |
| 387 | } |
| 388 | |
| 389 | /* Verify body signature is inside the signed data */ |
| 390 | if (vb2_verify_signature_inside(preamble, sig->data_size, |
| 391 | &preamble->body_signature)) { |
| 392 | VB2_DEBUG("Firmware body signature off end of preamble\n"); |
| 393 | return VB2_ERROR_BAD_PREAMBLE; |
| 394 | } |
| 395 | |
| 396 | /* Verify kernel subkey is inside the signed data */ |
| 397 | if (vb2_verify_packed_key_inside(preamble, sig->data_size, |
| 398 | &preamble->kernel_subkey)) { |
| 399 | VB2_DEBUG("Kernel subkey off end of preamble\n"); |
| 400 | return VB2_ERROR_BAD_PREAMBLE; |
| 401 | } |
| 402 | |
| 403 | /* Success */ |
| 404 | return VB2_SUCCESS; |
| 405 | } |