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authorTao Bao2017-03-16 19:37:38 -0500
committerTao Bao2017-03-17 16:07:12 -0500
commit5e535014dd7961fbf812abeaa27f3339775031f1 (patch)
tree5b0df6618eb06633342242f917a2fcd020e8e78f /verifier.cpp
parentdd553d280f3dabf8b2bd01d63111206d4ccb098c (diff)
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Drop the dependency on 'ui' in verify_file().
verify_file() has a dependency on the global variable of 'ui' for posting the verification progress, which requires the users of libverifier to provide a UI instance. This CL adds an optional argument to verify_file() so that it can post the progress through the provided callback function. As a result, we can drop the MockUI class in verifier_test.cpp. Test: recovery_component_test passes. Test: verify_file() posts progress update when installing an OTA. Change-Id: I8b87d0f0d99777ea755d33d6dbbe2b6d44243bf1
Diffstat (limited to 'verifier.cpp')
-rw-r--r--verifier.cpp329
1 files changed, 161 insertions, 168 deletions
diff --git a/verifier.cpp b/verifier.cpp
index 44098f70..00e13aa7 100644
--- a/verifier.cpp
+++ b/verifier.cpp
@@ -21,6 +21,7 @@
21#include <stdlib.h> 21#include <stdlib.h>
22#include <string.h> 22#include <string.h>
23 23
24#include <functional>
24#include <algorithm> 25#include <algorithm>
25#include <memory> 26#include <memory>
26 27
@@ -108,201 +109,193 @@ static bool read_pkcs7(uint8_t* pkcs7_der, size_t pkcs7_der_len, uint8_t** sig_d
108 return *sig_der != NULL; 109 return *sig_der != NULL;
109} 110}
110 111
111// Look for an RSA signature embedded in the .ZIP file comment given 112/*
112// the path to the zip. Verify it matches one of the given public 113 * Looks for an RSA signature embedded in the .ZIP file comment given the path to the zip. Verifies
113// keys. 114 * that it matches one of the given public keys. A callback function can be optionally provided for
114// 115 * posting the progress.
115// Return VERIFY_SUCCESS, VERIFY_FAILURE (if any error is encountered 116 *
116// or no key matches the signature). 117 * Returns VERIFY_SUCCESS or VERIFY_FAILURE (if any error is encountered or no key matches the
117 118 * signature).
118int verify_file(unsigned char* addr, size_t length, 119 */
119 const std::vector<Certificate>& keys) { 120int verify_file(unsigned char* addr, size_t length, const std::vector<Certificate>& keys,
120 ui->SetProgress(0.0); 121 const std::function<void(float)>& set_progress) {
121 122 if (set_progress) {
122 // An archive with a whole-file signature will end in six bytes: 123 set_progress(0.0);
123 // 124 }
124 // (2-byte signature start) $ff $ff (2-byte comment size) 125
125 // 126 // An archive with a whole-file signature will end in six bytes:
126 // (As far as the ZIP format is concerned, these are part of the 127 //
127 // archive comment.) We start by reading this footer, this tells 128 // (2-byte signature start) $ff $ff (2-byte comment size)
128 // us how far back from the end we have to start reading to find 129 //
129 // the whole comment. 130 // (As far as the ZIP format is concerned, these are part of the archive comment.) We start by
131 // reading this footer, this tells us how far back from the end we have to start reading to find
132 // the whole comment.
130 133
131#define FOOTER_SIZE 6 134#define FOOTER_SIZE 6
132 135
133 if (length < FOOTER_SIZE) { 136 if (length < FOOTER_SIZE) {
134 LOG(ERROR) << "not big enough to contain footer"; 137 LOG(ERROR) << "not big enough to contain footer";
135 return VERIFY_FAILURE; 138 return VERIFY_FAILURE;
136 } 139 }
137 140
138 unsigned char* footer = addr + length - FOOTER_SIZE; 141 unsigned char* footer = addr + length - FOOTER_SIZE;
139 142
140 if (footer[2] != 0xff || footer[3] != 0xff) { 143 if (footer[2] != 0xff || footer[3] != 0xff) {
141 LOG(ERROR) << "footer is wrong"; 144 LOG(ERROR) << "footer is wrong";
142 return VERIFY_FAILURE; 145 return VERIFY_FAILURE;
143 } 146 }
144 147
145 size_t comment_size = footer[4] + (footer[5] << 8); 148 size_t comment_size = footer[4] + (footer[5] << 8);
146 size_t signature_start = footer[0] + (footer[1] << 8); 149 size_t signature_start = footer[0] + (footer[1] << 8);
147 LOG(INFO) << "comment is " << comment_size << " bytes; signature is " << signature_start 150 LOG(INFO) << "comment is " << comment_size << " bytes; signature is " << signature_start
148 << " bytes from end"; 151 << " bytes from end";
149 152
150 if (signature_start <= FOOTER_SIZE) { 153 if (signature_start <= FOOTER_SIZE) {
151 LOG(ERROR) << "Signature start is in the footer"; 154 LOG(ERROR) << "Signature start is in the footer";
152 return VERIFY_FAILURE; 155 return VERIFY_FAILURE;
153 } 156 }
154 157
155#define EOCD_HEADER_SIZE 22 158#define EOCD_HEADER_SIZE 22
156 159
157 // The end-of-central-directory record is 22 bytes plus any 160 // The end-of-central-directory record is 22 bytes plus any comment length.
158 // comment length. 161 size_t eocd_size = comment_size + EOCD_HEADER_SIZE;
159 size_t eocd_size = comment_size + EOCD_HEADER_SIZE;
160 162
161 if (length < eocd_size) { 163 if (length < eocd_size) {
162 LOG(ERROR) << "not big enough to contain EOCD"; 164 LOG(ERROR) << "not big enough to contain EOCD";
163 return VERIFY_FAILURE; 165 return VERIFY_FAILURE;
164 } 166 }
165 167
166 // Determine how much of the file is covered by the signature. 168 // Determine how much of the file is covered by the signature. This is everything except the
167 // This is everything except the signature data and length, which 169 // signature data and length, which includes all of the EOCD except for the comment length field
168 // includes all of the EOCD except for the comment length field (2 170 // (2 bytes) and the comment data.
169 // bytes) and the comment data. 171 size_t signed_len = length - eocd_size + EOCD_HEADER_SIZE - 2;
170 size_t signed_len = length - eocd_size + EOCD_HEADER_SIZE - 2;
171 172
172 unsigned char* eocd = addr + length - eocd_size; 173 unsigned char* eocd = addr + length - eocd_size;
173 174
174 // If this is really is the EOCD record, it will begin with the 175 // If this is really is the EOCD record, it will begin with the magic number $50 $4b $05 $06.
175 // magic number $50 $4b $05 $06. 176 if (eocd[0] != 0x50 || eocd[1] != 0x4b || eocd[2] != 0x05 || eocd[3] != 0x06) {
176 if (eocd[0] != 0x50 || eocd[1] != 0x4b || 177 LOG(ERROR) << "signature length doesn't match EOCD marker";
177 eocd[2] != 0x05 || eocd[3] != 0x06) { 178 return VERIFY_FAILURE;
178 LOG(ERROR) << "signature length doesn't match EOCD marker"; 179 }
179 return VERIFY_FAILURE;
180 }
181 180
182 for (size_t i = 4; i < eocd_size-3; ++i) { 181 for (size_t i = 4; i < eocd_size-3; ++i) {
183 if (eocd[i ] == 0x50 && eocd[i+1] == 0x4b && 182 if (eocd[i ] == 0x50 && eocd[i+1] == 0x4b && eocd[i+2] == 0x05 && eocd[i+3] == 0x06) {
184 eocd[i+2] == 0x05 && eocd[i+3] == 0x06) { 183 // If the sequence $50 $4b $05 $06 appears anywhere after the real one, libziparchive will
185 // if the sequence $50 $4b $05 $06 appears anywhere after 184 // find the later (wrong) one, which could be exploitable. Fail the verification if this
186 // the real one, libziparchive will find the later (wrong) one, 185 // sequence occurs anywhere after the real one.
187 // which could be exploitable. Fail verification if 186 LOG(ERROR) << "EOCD marker occurs after start of EOCD";
188 // this sequence occurs anywhere after the real one. 187 return VERIFY_FAILURE;
189 LOG(ERROR) << "EOCD marker occurs after start of EOCD";
190 return VERIFY_FAILURE;
191 }
192 } 188 }
189 }
193 190
194 bool need_sha1 = false; 191 bool need_sha1 = false;
195 bool need_sha256 = false; 192 bool need_sha256 = false;
196 for (const auto& key : keys) { 193 for (const auto& key : keys) {
197 switch (key.hash_len) { 194 switch (key.hash_len) {
198 case SHA_DIGEST_LENGTH: need_sha1 = true; break; 195 case SHA_DIGEST_LENGTH: need_sha1 = true; break;
199 case SHA256_DIGEST_LENGTH: need_sha256 = true; break; 196 case SHA256_DIGEST_LENGTH: need_sha256 = true; break;
200 }
201 } 197 }
198 }
202 199
203 SHA_CTX sha1_ctx; 200 SHA_CTX sha1_ctx;
204 SHA256_CTX sha256_ctx; 201 SHA256_CTX sha256_ctx;
205 SHA1_Init(&sha1_ctx); 202 SHA1_Init(&sha1_ctx);
206 SHA256_Init(&sha256_ctx); 203 SHA256_Init(&sha256_ctx);
207 204
208 double frac = -1.0; 205 double frac = -1.0;
209 size_t so_far = 0; 206 size_t so_far = 0;
210 while (so_far < signed_len) { 207 while (so_far < signed_len) {
211 // On a Nexus 5X, experiment showed 16MiB beat 1MiB by 6% faster for a 208 // On a Nexus 5X, experiment showed 16MiB beat 1MiB by 6% faster for a
212 // 1196MiB full OTA and 60% for an 89MiB incremental OTA. 209 // 1196MiB full OTA and 60% for an 89MiB incremental OTA.
213 // http://b/28135231. 210 // http://b/28135231.
214 size_t size = std::min(signed_len - so_far, 16 * MiB); 211 size_t size = std::min(signed_len - so_far, 16 * MiB);
215 212
216 if (need_sha1) SHA1_Update(&sha1_ctx, addr + so_far, size); 213 if (need_sha1) SHA1_Update(&sha1_ctx, addr + so_far, size);
217 if (need_sha256) SHA256_Update(&sha256_ctx, addr + so_far, size); 214 if (need_sha256) SHA256_Update(&sha256_ctx, addr + so_far, size);
218 so_far += size; 215 so_far += size;
219 216
220 double f = so_far / (double)signed_len; 217 if (set_progress) {
221 if (f > frac + 0.02 || size == so_far) { 218 double f = so_far / (double)signed_len;
222 ui->SetProgress(f); 219 if (f > frac + 0.02 || size == so_far) {
223 frac = f; 220 set_progress(f);
224 } 221 frac = f;
222 }
225 } 223 }
224 }
226 225
227 uint8_t sha1[SHA_DIGEST_LENGTH]; 226 uint8_t sha1[SHA_DIGEST_LENGTH];
228 SHA1_Final(sha1, &sha1_ctx); 227 SHA1_Final(sha1, &sha1_ctx);
229 uint8_t sha256[SHA256_DIGEST_LENGTH]; 228 uint8_t sha256[SHA256_DIGEST_LENGTH];
230 SHA256_Final(sha256, &sha256_ctx); 229 SHA256_Final(sha256, &sha256_ctx);
231
232 uint8_t* sig_der = nullptr;
233 size_t sig_der_length = 0;
234
235 uint8_t* signature = eocd + eocd_size - signature_start;
236 size_t signature_size = signature_start - FOOTER_SIZE;
237
238 LOG(INFO) << "signature (offset: " << std::hex << (length - signature_start) << ", length: "
239 << signature_size << "): " << print_hex(signature, signature_size);
240 230
241 if (!read_pkcs7(signature, signature_size, &sig_der, &sig_der_length)) { 231 uint8_t* sig_der = nullptr;
242 LOG(ERROR) << "Could not find signature DER block"; 232 size_t sig_der_length = 0;
243 return VERIFY_FAILURE;
244 }
245 233
246 /* 234 uint8_t* signature = eocd + eocd_size - signature_start;
247 * Check to make sure at least one of the keys matches the signature. Since 235 size_t signature_size = signature_start - FOOTER_SIZE;
248 * any key can match, we need to try each before determining a verification
249 * failure has happened.
250 */
251 size_t i = 0;
252 for (const auto& key : keys) {
253 const uint8_t* hash;
254 int hash_nid;
255 switch (key.hash_len) {
256 case SHA_DIGEST_LENGTH:
257 hash = sha1;
258 hash_nid = NID_sha1;
259 break;
260 case SHA256_DIGEST_LENGTH:
261 hash = sha256;
262 hash_nid = NID_sha256;
263 break;
264 default:
265 continue;
266 }
267 236
268 // The 6 bytes is the "(signature_start) $ff $ff (comment_size)" that 237 LOG(INFO) << "signature (offset: " << std::hex << (length - signature_start) << ", length: "
269 // the signing tool appends after the signature itself. 238 << signature_size << "): " << print_hex(signature, signature_size);
270 if (key.key_type == Certificate::KEY_TYPE_RSA) {
271 if (!RSA_verify(hash_nid, hash, key.hash_len, sig_der,
272 sig_der_length, key.rsa.get())) {
273 LOG(INFO) << "failed to verify against RSA key " << i;
274 continue;
275 }
276 239
277 LOG(INFO) << "whole-file signature verified against RSA key " << i; 240 if (!read_pkcs7(signature, signature_size, &sig_der, &sig_der_length)) {
278 free(sig_der); 241 LOG(ERROR) << "Could not find signature DER block";
279 return VERIFY_SUCCESS; 242 return VERIFY_FAILURE;
280 } else if (key.key_type == Certificate::KEY_TYPE_EC 243 }
281 && key.hash_len == SHA256_DIGEST_LENGTH) {
282 if (!ECDSA_verify(0, hash, key.hash_len, sig_der,
283 sig_der_length, key.ec.get())) {
284 LOG(INFO) << "failed to verify against EC key " << i;
285 continue;
286 }
287 244
288 LOG(INFO) << "whole-file signature verified against EC key " << i; 245 // Check to make sure at least one of the keys matches the signature. Since any key can match,
289 free(sig_der); 246 // we need to try each before determining a verification failure has happened.
290 return VERIFY_SUCCESS; 247 size_t i = 0;
291 } else { 248 for (const auto& key : keys) {
292 LOG(INFO) << "Unknown key type " << key.key_type; 249 const uint8_t* hash;
293 } 250 int hash_nid;
294 i++; 251 switch (key.hash_len) {
295 } 252 case SHA_DIGEST_LENGTH:
253 hash = sha1;
254 hash_nid = NID_sha1;
255 break;
256 case SHA256_DIGEST_LENGTH:
257 hash = sha256;
258 hash_nid = NID_sha256;
259 break;
260 default:
261 continue;
262 }
263
264 // The 6 bytes is the "(signature_start) $ff $ff (comment_size)" that the signing tool appends
265 // after the signature itself.
266 if (key.key_type == Certificate::KEY_TYPE_RSA) {
267 if (!RSA_verify(hash_nid, hash, key.hash_len, sig_der, sig_der_length, key.rsa.get())) {
268 LOG(INFO) << "failed to verify against RSA key " << i;
269 continue;
270 }
271
272 LOG(INFO) << "whole-file signature verified against RSA key " << i;
273 free(sig_der);
274 return VERIFY_SUCCESS;
275 } else if (key.key_type == Certificate::KEY_TYPE_EC && key.hash_len == SHA256_DIGEST_LENGTH) {
276 if (!ECDSA_verify(0, hash, key.hash_len, sig_der, sig_der_length, key.ec.get())) {
277 LOG(INFO) << "failed to verify against EC key " << i;
278 continue;
279 }
280
281 LOG(INFO) << "whole-file signature verified against EC key " << i;
282 free(sig_der);
283 return VERIFY_SUCCESS;
284 } else {
285 LOG(INFO) << "Unknown key type " << key.key_type;
286 }
287 i++;
288 }
296 289
297 if (need_sha1) { 290 if (need_sha1) {
298 LOG(INFO) << "SHA-1 digest: " << print_hex(sha1, SHA_DIGEST_LENGTH); 291 LOG(INFO) << "SHA-1 digest: " << print_hex(sha1, SHA_DIGEST_LENGTH);
299 } 292 }
300 if (need_sha256) { 293 if (need_sha256) {
301 LOG(INFO) << "SHA-256 digest: " << print_hex(sha256, SHA256_DIGEST_LENGTH); 294 LOG(INFO) << "SHA-256 digest: " << print_hex(sha256, SHA256_DIGEST_LENGTH);
302 } 295 }
303 free(sig_der); 296 free(sig_der);
304 LOG(ERROR) << "failed to verify whole-file signature"; 297 LOG(ERROR) << "failed to verify whole-file signature";
305 return VERIFY_FAILURE; 298 return VERIFY_FAILURE;
306} 299}
307 300
308std::unique_ptr<RSA, RSADeleter> parse_rsa_key(FILE* file, uint32_t exponent) { 301std::unique_ptr<RSA, RSADeleter> parse_rsa_key(FILE* file, uint32_t exponent) {