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path: root/libavb/avb_vbmeta_image.c (plain)
blob: 21bbf9295d58904316073812db3ba8194e30c963
1/*
2 * Copyright (C) 2016 The Android Open Source Project
3 *
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:
11 *
12 * The above copyright notice and this permission notice shall be
13 * included in all copies or substantial portions of the Software.
14 *
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.
23 */
24
25#include "avb_vbmeta_image.h"
26#include "avb_crypto.h"
27#include "avb_rsa.h"
28#include "avb_sha.h"
29#include "avb_util.h"
30#include "avb_version.h"
31
32AvbVBMetaVerifyResult avb_vbmeta_image_verify(
33 const uint8_t* data,
34 size_t length,
35 const uint8_t** out_public_key_data,
36 size_t* out_public_key_length) {
37 AvbVBMetaVerifyResult ret;
38 AvbVBMetaImageHeader h;
39 uint8_t* computed_hash;
40 const AvbAlgorithmData* algorithm;
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
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 }
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
71 /* Ensure we don't attempt to access any fields if we do not meet
72 * the specified minimum version of libavb.
73 */
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");
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
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;
139 if (!avb_safe_add(&pubkey_md_end,
140 h.public_key_metadata_offset,
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
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
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
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);
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);
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);
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);
196 computed_hash = avb_sha512_final(&sha512_ctx);
197 break;
198 default:
199 avb_error("Unknown algorithm.\n");
200 goto out;
201 }
202
203 if (avb_safe_memcmp(authentication_block + h.hash_offset,
204 computed_hash,
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 =
212 avb_rsa_verify(auxiliary_block + h.public_key_offset,
213 h.public_key_size,
214 authentication_block + h.signature_offset,
215 h.signature_size,
216 authentication_block + h.hash_offset,
217 h.hash_size,
218 algorithm->padding,
219 algorithm->padding_len);
220
221 if (verification_result == 0) {
222 ret = AVB_VBMETA_VERIFY_RESULT_SIGNATURE_MISMATCH;
223 goto out;
224 }
225
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 }
234
235 ret = AVB_VBMETA_VERIFY_RESULT_OK;
236
237out:
238 return ret;
239}
240
241void avb_vbmeta_image_header_to_host_byte_order(const AvbVBMetaImageHeader* src,
242 AvbVBMetaImageHeader* dest) {
243 avb_memcpy(dest, src, sizeof(AvbVBMetaImageHeader));
244
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);
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
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
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);
274 dest->flags = avb_be32toh(dest->flags);
275}
276
277const 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;
290 case AVB_VBMETA_VERIFY_RESULT_UNSUPPORTED_VERSION:
291 ret = "UNSUPPORTED_VERSION";
292 break;
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}
309
generated by cgit at 2024-05-18 13:28:39 (GMT)