David Zeuthen | 21e9526 | 2016-07-27 17:58:40 -0400 | [diff] [blame] | 1 | /* |
| 2 | * Copyright (C) 2016 The Android Open Source Project |
| 3 | * |
David Zeuthen | c612e2e | 2016-09-16 16:44:08 -0400 | [diff] [blame] | 4 | * Permission is hereby granted, free of charge, to any person |
| 5 | * obtaining a copy of this software and associated documentation |
| 6 | * files (the "Software"), to deal in the Software without |
| 7 | * restriction, including without limitation the rights to use, copy, |
| 8 | * modify, merge, publish, distribute, sublicense, and/or sell copies |
| 9 | * of the Software, and to permit persons to whom the Software is |
| 10 | * furnished to do so, subject to the following conditions: |
David Zeuthen | 21e9526 | 2016-07-27 17:58:40 -0400 | [diff] [blame] | 11 | * |
David Zeuthen | c612e2e | 2016-09-16 16:44:08 -0400 | [diff] [blame] | 12 | * The above copyright notice and this permission notice shall be |
| 13 | * included in all copies or substantial portions of the Software. |
David Zeuthen | 21e9526 | 2016-07-27 17:58:40 -0400 | [diff] [blame] | 14 | * |
David Zeuthen | c612e2e | 2016-09-16 16:44:08 -0400 | [diff] [blame] | 15 | * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, |
| 16 | * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF |
| 17 | * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND |
| 18 | * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS |
| 19 | * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN |
| 20 | * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN |
| 21 | * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE |
| 22 | * SOFTWARE. |
David Zeuthen | 21e9526 | 2016-07-27 17:58:40 -0400 | [diff] [blame] | 23 | */ |
| 24 | |
| 25 | #include "avb_vbmeta_image.h" |
Darren Krahn | c9fa424 | 2016-12-12 15:57:00 -0800 | [diff] [blame] | 26 | #include "avb_crypto.h" |
David Zeuthen | 21e9526 | 2016-07-27 17:58:40 -0400 | [diff] [blame] | 27 | #include "avb_rsa.h" |
| 28 | #include "avb_sha.h" |
| 29 | #include "avb_util.h" |
David Zeuthen | e3cadca | 2017-02-22 21:25:46 -0500 | [diff] [blame] | 30 | #include "avb_version.h" |
David Zeuthen | 21e9526 | 2016-07-27 17:58:40 -0400 | [diff] [blame] | 31 | |
David Zeuthen | 21e9526 | 2016-07-27 17:58:40 -0400 | [diff] [blame] | 32 | AvbVBMetaVerifyResult avb_vbmeta_image_verify( |
David Zeuthen | 4b6a634 | 2017-01-03 15:19:56 -0500 | [diff] [blame] | 33 | const uint8_t* data, |
| 34 | size_t length, |
| 35 | const uint8_t** out_public_key_data, |
David Zeuthen | 21e9526 | 2016-07-27 17:58:40 -0400 | [diff] [blame] | 36 | size_t* out_public_key_length) { |
| 37 | AvbVBMetaVerifyResult ret; |
| 38 | AvbVBMetaImageHeader h; |
| 39 | uint8_t* computed_hash; |
Darren Krahn | c9fa424 | 2016-12-12 15:57:00 -0800 | [diff] [blame] | 40 | const AvbAlgorithmData* algorithm; |
David Zeuthen | 21e9526 | 2016-07-27 17:58:40 -0400 | [diff] [blame] | 41 | AvbSHA256Ctx sha256_ctx; |
| 42 | AvbSHA512Ctx sha512_ctx; |
| 43 | const uint8_t* header_block; |
| 44 | const uint8_t* authentication_block; |
| 45 | const uint8_t* auxiliary_block; |
| 46 | int verification_result; |
| 47 | |
| 48 | ret = AVB_VBMETA_VERIFY_RESULT_INVALID_VBMETA_HEADER; |
| 49 | |
David Zeuthen | 0155e6b | 2016-11-16 17:58:13 -0500 | [diff] [blame] | 50 | if (out_public_key_data != NULL) { |
| 51 | *out_public_key_data = NULL; |
| 52 | } |
| 53 | if (out_public_key_length != NULL) { |
| 54 | *out_public_key_length = 0; |
| 55 | } |
David Zeuthen | 21e9526 | 2016-07-27 17:58:40 -0400 | [diff] [blame] | 56 | |
| 57 | /* Ensure magic is correct. */ |
| 58 | if (avb_safe_memcmp(data, AVB_MAGIC, AVB_MAGIC_LEN) != 0) { |
| 59 | avb_error("Magic is incorrect.\n"); |
| 60 | goto out; |
| 61 | } |
| 62 | |
| 63 | /* Before we byteswap, ensure length is long enough. */ |
| 64 | if (length < sizeof(AvbVBMetaImageHeader)) { |
| 65 | avb_error("Length is smaller than header.\n"); |
| 66 | goto out; |
| 67 | } |
| 68 | avb_vbmeta_image_header_to_host_byte_order((const AvbVBMetaImageHeader*)data, |
| 69 | &h); |
| 70 | |
David Zeuthen | e3cadca | 2017-02-22 21:25:46 -0500 | [diff] [blame] | 71 | /* Ensure we don't attempt to access any fields if we do not meet |
| 72 | * the specified minimum version of libavb. |
David Zeuthen | 21e9526 | 2016-07-27 17:58:40 -0400 | [diff] [blame] | 73 | */ |
David Zeuthen | e3cadca | 2017-02-22 21:25:46 -0500 | [diff] [blame] | 74 | if ((h.required_libavb_version_major != AVB_VERSION_MAJOR) || |
| 75 | (h.required_libavb_version_minor > AVB_VERSION_MINOR)) { |
| 76 | avb_error("Mismatch between image version and libavb version.\n"); |
| 77 | ret = AVB_VBMETA_VERIFY_RESULT_UNSUPPORTED_VERSION; |
| 78 | goto out; |
| 79 | } |
| 80 | |
| 81 | /* Ensure |release_string| ends with a NUL byte. */ |
| 82 | if (h.release_string[AVB_RELEASE_STRING_SIZE - 1] != '\0') { |
| 83 | avb_error("Release string does not end with a NUL byte.\n"); |
David Zeuthen | 21e9526 | 2016-07-27 17:58:40 -0400 | [diff] [blame] | 84 | goto out; |
| 85 | } |
| 86 | |
| 87 | /* Ensure inner block sizes are multiple of 64. */ |
| 88 | if ((h.authentication_data_block_size & 0x3f) != 0 || |
| 89 | (h.auxiliary_data_block_size & 0x3f) != 0) { |
| 90 | avb_error("Block size is not a multiple of 64.\n"); |
| 91 | goto out; |
| 92 | } |
| 93 | |
| 94 | /* Ensure block sizes all add up to at most |length|. */ |
| 95 | uint64_t block_total = sizeof(AvbVBMetaImageHeader); |
| 96 | if (!avb_safe_add_to(&block_total, h.authentication_data_block_size) || |
| 97 | !avb_safe_add_to(&block_total, h.auxiliary_data_block_size)) { |
| 98 | avb_error("Overflow while computing size of boot image.\n"); |
| 99 | goto out; |
| 100 | } |
| 101 | if (block_total > length) { |
| 102 | avb_error("Block sizes add up to more than given length.\n"); |
| 103 | goto out; |
| 104 | } |
| 105 | |
| 106 | uintptr_t data_ptr = (uintptr_t)data; |
| 107 | /* Ensure passed in memory doesn't wrap. */ |
| 108 | if (!avb_safe_add(NULL, (uint64_t)data_ptr, length)) { |
| 109 | avb_error("Boot image location and length mismatch.\n"); |
| 110 | goto out; |
| 111 | } |
| 112 | |
| 113 | /* Ensure hash and signature are entirely in the Authentication data block. */ |
| 114 | uint64_t hash_end; |
| 115 | if (!avb_safe_add(&hash_end, h.hash_offset, h.hash_size) || |
| 116 | hash_end > h.authentication_data_block_size) { |
| 117 | avb_error("Hash is not entirely in its block.\n"); |
| 118 | goto out; |
| 119 | } |
| 120 | uint64_t signature_end; |
| 121 | if (!avb_safe_add(&signature_end, h.signature_offset, h.signature_size) || |
| 122 | signature_end > h.authentication_data_block_size) { |
| 123 | avb_error("Signature is not entirely in its block.\n"); |
| 124 | goto out; |
| 125 | } |
| 126 | |
| 127 | /* Ensure public key is entirely in the Auxiliary data block. */ |
| 128 | uint64_t pubkey_end; |
| 129 | if (!avb_safe_add(&pubkey_end, h.public_key_offset, h.public_key_size) || |
| 130 | pubkey_end > h.auxiliary_data_block_size) { |
| 131 | avb_error("Public key is not entirely in its block.\n"); |
| 132 | goto out; |
| 133 | } |
| 134 | |
David Zeuthen | 18666ab | 2016-11-15 11:18:05 -0500 | [diff] [blame] | 135 | /* Ensure public key metadata (if set) is entirely in the Auxiliary |
| 136 | * data block. */ |
| 137 | if (h.public_key_metadata_size > 0) { |
| 138 | uint64_t pubkey_md_end; |
David Zeuthen | 4b6a634 | 2017-01-03 15:19:56 -0500 | [diff] [blame] | 139 | if (!avb_safe_add(&pubkey_md_end, |
| 140 | h.public_key_metadata_offset, |
David Zeuthen | 18666ab | 2016-11-15 11:18:05 -0500 | [diff] [blame] | 141 | h.public_key_metadata_size) || |
| 142 | pubkey_md_end > h.auxiliary_data_block_size) { |
| 143 | avb_error("Public key metadata is not entirely in its block.\n"); |
| 144 | goto out; |
| 145 | } |
| 146 | } |
| 147 | |
David Zeuthen | 21e9526 | 2016-07-27 17:58:40 -0400 | [diff] [blame] | 148 | /* Bail early if there's no hash or signature. */ |
| 149 | if (h.algorithm_type == AVB_ALGORITHM_TYPE_NONE) { |
| 150 | ret = AVB_VBMETA_VERIFY_RESULT_OK_NOT_SIGNED; |
| 151 | goto out; |
| 152 | } |
| 153 | |
Darren Krahn | c9fa424 | 2016-12-12 15:57:00 -0800 | [diff] [blame] | 154 | /* Ensure algorithm field is supported. */ |
| 155 | algorithm = avb_get_algorithm_data(h.algorithm_type); |
| 156 | if (!algorithm) { |
| 157 | avb_error("Invalid or unknown algorithm.\n"); |
| 158 | goto out; |
| 159 | } |
| 160 | |
David Zeuthen | 21e9526 | 2016-07-27 17:58:40 -0400 | [diff] [blame] | 161 | /* Bail if the embedded hash size doesn't match the chosen algorithm. */ |
| 162 | if (h.hash_size != algorithm->hash_len) { |
| 163 | avb_error("Embedded hash has wrong size.\n"); |
| 164 | goto out; |
| 165 | } |
| 166 | |
| 167 | /* No overflow checks needed from here-on after since all block |
| 168 | * sizes and offsets have been verified above. |
| 169 | */ |
| 170 | |
| 171 | header_block = data; |
| 172 | authentication_block = header_block + sizeof(AvbVBMetaImageHeader); |
| 173 | auxiliary_block = authentication_block + h.authentication_data_block_size; |
| 174 | |
| 175 | switch (h.algorithm_type) { |
| 176 | /* Explicit fall-through: */ |
| 177 | case AVB_ALGORITHM_TYPE_SHA256_RSA2048: |
| 178 | case AVB_ALGORITHM_TYPE_SHA256_RSA4096: |
| 179 | case AVB_ALGORITHM_TYPE_SHA256_RSA8192: |
| 180 | avb_sha256_init(&sha256_ctx); |
David Zeuthen | 4b6a634 | 2017-01-03 15:19:56 -0500 | [diff] [blame] | 181 | avb_sha256_update( |
| 182 | &sha256_ctx, header_block, sizeof(AvbVBMetaImageHeader)); |
| 183 | avb_sha256_update( |
| 184 | &sha256_ctx, auxiliary_block, h.auxiliary_data_block_size); |
David Zeuthen | 21e9526 | 2016-07-27 17:58:40 -0400 | [diff] [blame] | 185 | computed_hash = avb_sha256_final(&sha256_ctx); |
| 186 | break; |
| 187 | /* Explicit fall-through: */ |
| 188 | case AVB_ALGORITHM_TYPE_SHA512_RSA2048: |
| 189 | case AVB_ALGORITHM_TYPE_SHA512_RSA4096: |
| 190 | case AVB_ALGORITHM_TYPE_SHA512_RSA8192: |
| 191 | avb_sha512_init(&sha512_ctx); |
David Zeuthen | 4b6a634 | 2017-01-03 15:19:56 -0500 | [diff] [blame] | 192 | avb_sha512_update( |
| 193 | &sha512_ctx, header_block, sizeof(AvbVBMetaImageHeader)); |
| 194 | avb_sha512_update( |
| 195 | &sha512_ctx, auxiliary_block, h.auxiliary_data_block_size); |
David Zeuthen | 21e9526 | 2016-07-27 17:58:40 -0400 | [diff] [blame] | 196 | computed_hash = avb_sha512_final(&sha512_ctx); |
| 197 | break; |
| 198 | default: |
| 199 | avb_error("Unknown algorithm.\n"); |
| 200 | goto out; |
| 201 | } |
| 202 | |
David Zeuthen | 4b6a634 | 2017-01-03 15:19:56 -0500 | [diff] [blame] | 203 | if (avb_safe_memcmp(authentication_block + h.hash_offset, |
| 204 | computed_hash, |
David Zeuthen | 21e9526 | 2016-07-27 17:58:40 -0400 | [diff] [blame] | 205 | h.hash_size) != 0) { |
| 206 | avb_error("Hash does not match!\n"); |
| 207 | ret = AVB_VBMETA_VERIFY_RESULT_HASH_MISMATCH; |
| 208 | goto out; |
| 209 | } |
| 210 | |
| 211 | verification_result = |
David Zeuthen | 4b6a634 | 2017-01-03 15:19:56 -0500 | [diff] [blame] | 212 | avb_rsa_verify(auxiliary_block + h.public_key_offset, |
| 213 | h.public_key_size, |
David Zeuthen | 21e9526 | 2016-07-27 17:58:40 -0400 | [diff] [blame] | 214 | authentication_block + h.signature_offset, |
David Zeuthen | 4b6a634 | 2017-01-03 15:19:56 -0500 | [diff] [blame] | 215 | h.signature_size, |
| 216 | authentication_block + h.hash_offset, |
| 217 | h.hash_size, |
| 218 | algorithm->padding, |
| 219 | algorithm->padding_len); |
David Zeuthen | 21e9526 | 2016-07-27 17:58:40 -0400 | [diff] [blame] | 220 | |
| 221 | if (verification_result == 0) { |
| 222 | ret = AVB_VBMETA_VERIFY_RESULT_SIGNATURE_MISMATCH; |
| 223 | goto out; |
| 224 | } |
| 225 | |
David Zeuthen | 0155e6b | 2016-11-16 17:58:13 -0500 | [diff] [blame] | 226 | if (h.public_key_size > 0) { |
| 227 | if (out_public_key_data != NULL) { |
| 228 | *out_public_key_data = auxiliary_block + h.public_key_offset; |
| 229 | } |
| 230 | if (out_public_key_length != NULL) { |
| 231 | *out_public_key_length = h.public_key_size; |
| 232 | } |
| 233 | } |
David Zeuthen | 21e9526 | 2016-07-27 17:58:40 -0400 | [diff] [blame] | 234 | |
| 235 | ret = AVB_VBMETA_VERIFY_RESULT_OK; |
| 236 | |
| 237 | out: |
| 238 | return ret; |
| 239 | } |
| 240 | |
| 241 | void avb_vbmeta_image_header_to_host_byte_order(const AvbVBMetaImageHeader* src, |
| 242 | AvbVBMetaImageHeader* dest) { |
| 243 | avb_memcpy(dest, src, sizeof(AvbVBMetaImageHeader)); |
| 244 | |
David Zeuthen | e3cadca | 2017-02-22 21:25:46 -0500 | [diff] [blame] | 245 | dest->required_libavb_version_major = |
| 246 | avb_be32toh(dest->required_libavb_version_major); |
| 247 | dest->required_libavb_version_minor = |
| 248 | avb_be32toh(dest->required_libavb_version_minor); |
David Zeuthen | 21e9526 | 2016-07-27 17:58:40 -0400 | [diff] [blame] | 249 | |
| 250 | dest->authentication_data_block_size = |
| 251 | avb_be64toh(dest->authentication_data_block_size); |
| 252 | dest->auxiliary_data_block_size = |
| 253 | avb_be64toh(dest->auxiliary_data_block_size); |
| 254 | |
| 255 | dest->algorithm_type = avb_be32toh(dest->algorithm_type); |
| 256 | |
| 257 | dest->hash_offset = avb_be64toh(dest->hash_offset); |
| 258 | dest->hash_size = avb_be64toh(dest->hash_size); |
| 259 | |
| 260 | dest->signature_offset = avb_be64toh(dest->signature_offset); |
| 261 | dest->signature_size = avb_be64toh(dest->signature_size); |
| 262 | |
| 263 | dest->public_key_offset = avb_be64toh(dest->public_key_offset); |
| 264 | dest->public_key_size = avb_be64toh(dest->public_key_size); |
| 265 | |
David Zeuthen | 18666ab | 2016-11-15 11:18:05 -0500 | [diff] [blame] | 266 | dest->public_key_metadata_offset = |
| 267 | avb_be64toh(dest->public_key_metadata_offset); |
| 268 | dest->public_key_metadata_size = avb_be64toh(dest->public_key_metadata_size); |
| 269 | |
David Zeuthen | 21e9526 | 2016-07-27 17:58:40 -0400 | [diff] [blame] | 270 | dest->descriptors_offset = avb_be64toh(dest->descriptors_offset); |
| 271 | dest->descriptors_size = avb_be64toh(dest->descriptors_size); |
| 272 | |
| 273 | dest->rollback_index = avb_be64toh(dest->rollback_index); |
David Zeuthen | fd41eb9 | 2016-11-17 12:24:47 -0500 | [diff] [blame] | 274 | dest->flags = avb_be32toh(dest->flags); |
David Zeuthen | 21e9526 | 2016-07-27 17:58:40 -0400 | [diff] [blame] | 275 | } |
David Zeuthen | 0155e6b | 2016-11-16 17:58:13 -0500 | [diff] [blame] | 276 | |
| 277 | const char* avb_vbmeta_verify_result_to_string(AvbVBMetaVerifyResult result) { |
| 278 | const char* ret = NULL; |
| 279 | |
| 280 | switch (result) { |
| 281 | case AVB_VBMETA_VERIFY_RESULT_OK: |
| 282 | ret = "OK"; |
| 283 | break; |
| 284 | case AVB_VBMETA_VERIFY_RESULT_OK_NOT_SIGNED: |
| 285 | ret = "OK_NOT_SIGNED"; |
| 286 | break; |
| 287 | case AVB_VBMETA_VERIFY_RESULT_INVALID_VBMETA_HEADER: |
| 288 | ret = "INVALID_VBMETA_HEADER"; |
| 289 | break; |
David Zeuthen | e3cadca | 2017-02-22 21:25:46 -0500 | [diff] [blame] | 290 | case AVB_VBMETA_VERIFY_RESULT_UNSUPPORTED_VERSION: |
| 291 | ret = "UNSUPPORTED_VERSION"; |
| 292 | break; |
David Zeuthen | 0155e6b | 2016-11-16 17:58:13 -0500 | [diff] [blame] | 293 | case AVB_VBMETA_VERIFY_RESULT_HASH_MISMATCH: |
| 294 | ret = "HASH_MISMATCH"; |
| 295 | break; |
| 296 | case AVB_VBMETA_VERIFY_RESULT_SIGNATURE_MISMATCH: |
| 297 | ret = "SIGNATURE_MISMATCH"; |
| 298 | break; |
| 299 | /* Do not add a 'default:' case here because of -Wswitch. */ |
| 300 | } |
| 301 | |
| 302 | if (ret == NULL) { |
| 303 | avb_error("Unknown AvbVBMetaVerifyResult value.\n"); |
| 304 | ret = "(unknown)"; |
| 305 | } |
| 306 | |
| 307 | return ret; |
| 308 | } |