summaryrefslogtreecommitdiffstats
path: root/verifier24
diff options
context:
space:
mode:
Diffstat (limited to 'verifier24')
-rw-r--r--verifier24/README2
-rw-r--r--verifier24/verifier.cpp471
-rw-r--r--verifier24/verifier.h58
3 files changed, 531 insertions, 0 deletions
diff --git a/verifier24/README b/verifier24/README
new file mode 100644
index 000000000..44d9422e9
--- /dev/null
+++ b/verifier24/README
@@ -0,0 +1,2 @@
+This is older code from Android 5.1 Marshmallow (SDK ver 24) and older
+that still used mincrypt instead of libcrypto.
diff --git a/verifier24/verifier.cpp b/verifier24/verifier.cpp
new file mode 100644
index 000000000..98c733732
--- /dev/null
+++ b/verifier24/verifier.cpp
@@ -0,0 +1,471 @@
+/*
+ * Copyright (C) 2008 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "asn1_decoder.h"
+#include "common.h"
+#include "ui.h"
+#include "verifier.h"
+
+#include "mincrypt/dsa_sig.h"
+#include "mincrypt/p256.h"
+#include "mincrypt/p256_ecdsa.h"
+#include "mincrypt/rsa.h"
+#include "mincrypt/sha.h"
+#include "mincrypt/sha256.h"
+
+#include <errno.h>
+#include <malloc.h>
+#include <stdio.h>
+#include <string.h>
+
+//extern RecoveryUI* ui;
+
+#define PUBLIC_KEYS_FILE "/res/keys"
+
+/*
+ * Simple version of PKCS#7 SignedData extraction. This extracts the
+ * signature OCTET STRING to be used for signature verification.
+ *
+ * For full details, see http://www.ietf.org/rfc/rfc3852.txt
+ *
+ * The PKCS#7 structure looks like:
+ *
+ * SEQUENCE (ContentInfo)
+ * OID (ContentType)
+ * [0] (content)
+ * SEQUENCE (SignedData)
+ * INTEGER (version CMSVersion)
+ * SET (DigestAlgorithmIdentifiers)
+ * SEQUENCE (EncapsulatedContentInfo)
+ * [0] (CertificateSet OPTIONAL)
+ * [1] (RevocationInfoChoices OPTIONAL)
+ * SET (SignerInfos)
+ * SEQUENCE (SignerInfo)
+ * INTEGER (CMSVersion)
+ * SEQUENCE (SignerIdentifier)
+ * SEQUENCE (DigestAlgorithmIdentifier)
+ * SEQUENCE (SignatureAlgorithmIdentifier)
+ * OCTET STRING (SignatureValue)
+ */
+static bool read_pkcs7(uint8_t* pkcs7_der, size_t pkcs7_der_len, uint8_t** sig_der,
+ size_t* sig_der_length) {
+ asn1_context_t* ctx = asn1_context_new(pkcs7_der, pkcs7_der_len);
+ if (ctx == NULL) {
+ return false;
+ }
+
+ asn1_context_t* pkcs7_seq = asn1_sequence_get(ctx);
+ if (pkcs7_seq != NULL && asn1_sequence_next(pkcs7_seq)) {
+ asn1_context_t *signed_data_app = asn1_constructed_get(pkcs7_seq);
+ if (signed_data_app != NULL) {
+ asn1_context_t* signed_data_seq = asn1_sequence_get(signed_data_app);
+ if (signed_data_seq != NULL
+ && asn1_sequence_next(signed_data_seq)
+ && asn1_sequence_next(signed_data_seq)
+ && asn1_sequence_next(signed_data_seq)
+ && asn1_constructed_skip_all(signed_data_seq)) {
+ asn1_context_t *sig_set = asn1_set_get(signed_data_seq);
+ if (sig_set != NULL) {
+ asn1_context_t* sig_seq = asn1_sequence_get(sig_set);
+ if (sig_seq != NULL
+ && asn1_sequence_next(sig_seq)
+ && asn1_sequence_next(sig_seq)
+ && asn1_sequence_next(sig_seq)
+ && asn1_sequence_next(sig_seq)) {
+ uint8_t* sig_der_ptr;
+ if (asn1_octet_string_get(sig_seq, &sig_der_ptr, sig_der_length)) {
+ *sig_der = (uint8_t*) malloc(*sig_der_length);
+ if (*sig_der != NULL) {
+ memcpy(*sig_der, sig_der_ptr, *sig_der_length);
+ }
+ }
+ asn1_context_free(sig_seq);
+ }
+ asn1_context_free(sig_set);
+ }
+ asn1_context_free(signed_data_seq);
+ }
+ asn1_context_free(signed_data_app);
+ }
+ asn1_context_free(pkcs7_seq);
+ }
+ asn1_context_free(ctx);
+
+ return *sig_der != NULL;
+}
+
+// Look for an RSA signature embedded in the .ZIP file comment given
+// the path to the zip. Verify it matches one of the given public
+// keys.
+//
+// Return VERIFY_SUCCESS, VERIFY_FAILURE (if any error is encountered
+// or no key matches the signature).
+int verify_file(unsigned char* addr, size_t length) {
+ //ui->SetProgress(0.0);
+
+ int numKeys;
+ Certificate* pKeys = load_keys(PUBLIC_KEYS_FILE, &numKeys);
+ if (pKeys == NULL) {
+ LOGE("Failed to load keys\n");
+ return INSTALL_CORRUPT;
+ }
+ LOGI("%d key(s) loaded from %s\n", numKeys, PUBLIC_KEYS_FILE);
+
+ // An archive with a whole-file signature will end in six bytes:
+ //
+ // (2-byte signature start) $ff $ff (2-byte comment size)
+ //
+ // (As far as the ZIP format is concerned, these are part of the
+ // archive comment.) We start by reading this footer, this tells
+ // us how far back from the end we have to start reading to find
+ // the whole comment.
+
+#define FOOTER_SIZE 6
+
+ if (length < FOOTER_SIZE) {
+ LOGE("not big enough to contain footer\n");
+ return VERIFY_FAILURE;
+ }
+
+ unsigned char* footer = addr + length - FOOTER_SIZE;
+
+ if (footer[2] != 0xff || footer[3] != 0xff) {
+ LOGE("footer is wrong\n");
+ return VERIFY_FAILURE;
+ }
+
+ size_t comment_size = footer[4] + (footer[5] << 8);
+ size_t signature_start = footer[0] + (footer[1] << 8);
+ LOGI("comment is %zu bytes; signature %zu bytes from end\n",
+ comment_size, signature_start);
+
+ if (signature_start <= FOOTER_SIZE) {
+ LOGE("Signature start is in the footer");
+ return VERIFY_FAILURE;
+ }
+
+#define EOCD_HEADER_SIZE 22
+
+ // The end-of-central-directory record is 22 bytes plus any
+ // comment length.
+ size_t eocd_size = comment_size + EOCD_HEADER_SIZE;
+
+ if (length < eocd_size) {
+ LOGE("not big enough to contain EOCD\n");
+ return VERIFY_FAILURE;
+ }
+
+ // Determine how much of the file is covered by the signature.
+ // This is everything except the signature data and length, which
+ // includes all of the EOCD except for the comment length field (2
+ // bytes) and the comment data.
+ size_t signed_len = length - eocd_size + EOCD_HEADER_SIZE - 2;
+
+ unsigned char* eocd = addr + length - eocd_size;
+
+ // If this is really is the EOCD record, it will begin with the
+ // magic number $50 $4b $05 $06.
+ if (eocd[0] != 0x50 || eocd[1] != 0x4b ||
+ eocd[2] != 0x05 || eocd[3] != 0x06) {
+ LOGE("signature length doesn't match EOCD marker\n");
+ return VERIFY_FAILURE;
+ }
+
+ size_t i;
+ for (i = 4; i < eocd_size-3; ++i) {
+ if (eocd[i ] == 0x50 && eocd[i+1] == 0x4b &&
+ eocd[i+2] == 0x05 && eocd[i+3] == 0x06) {
+ // if the sequence $50 $4b $05 $06 appears anywhere after
+ // the real one, minzip will find the later (wrong) one,
+ // which could be exploitable. Fail verification if
+ // this sequence occurs anywhere after the real one.
+ LOGE("EOCD marker occurs after start of EOCD\n");
+ return VERIFY_FAILURE;
+ }
+ }
+
+#define BUFFER_SIZE 4096
+
+ bool need_sha1 = false;
+ bool need_sha256 = false;
+ for (i = 0; i < numKeys; ++i) {
+ switch (pKeys[i].hash_len) {
+ case SHA_DIGEST_SIZE: need_sha1 = true; break;
+ case SHA256_DIGEST_SIZE: need_sha256 = true; break;
+ }
+ }
+
+ SHA_CTX sha1_ctx;
+ SHA256_CTX sha256_ctx;
+ SHA_init(&sha1_ctx);
+ SHA256_init(&sha256_ctx);
+
+ double frac = -1.0;
+ size_t so_far = 0;
+ while (so_far < signed_len) {
+ size_t size = signed_len - so_far;
+ if (size > BUFFER_SIZE) size = BUFFER_SIZE;
+
+ if (need_sha1) SHA_update(&sha1_ctx, addr + so_far, size);
+ if (need_sha256) SHA256_update(&sha256_ctx, addr + so_far, size);
+ so_far += size;
+
+ double f = so_far / (double)signed_len;
+ if (f > frac + 0.02 || size == so_far) {
+ //ui->SetProgress(f);
+ frac = f;
+ }
+ }
+
+ const uint8_t* sha1 = SHA_final(&sha1_ctx);
+ const uint8_t* sha256 = SHA256_final(&sha256_ctx);
+
+ uint8_t* sig_der = NULL;
+ size_t sig_der_length = 0;
+
+ size_t signature_size = signature_start - FOOTER_SIZE;
+ if (!read_pkcs7(eocd + eocd_size - signature_start, signature_size, &sig_der,
+ &sig_der_length)) {
+ LOGE("Could not find signature DER block\n");
+ return VERIFY_FAILURE;
+ }
+
+ /*
+ * Check to make sure at least one of the keys matches the signature. Since
+ * any key can match, we need to try each before determining a verification
+ * failure has happened.
+ */
+ for (i = 0; i < numKeys; ++i) {
+ const uint8_t* hash;
+ switch (pKeys[i].hash_len) {
+ case SHA_DIGEST_SIZE: hash = sha1; break;
+ case SHA256_DIGEST_SIZE: hash = sha256; break;
+ default: continue;
+ }
+
+ // The 6 bytes is the "(signature_start) $ff $ff (comment_size)" that
+ // the signing tool appends after the signature itself.
+ if (pKeys[i].key_type == Certificate::RSA) {
+ if (sig_der_length < RSANUMBYTES) {
+ // "signature" block isn't big enough to contain an RSA block.
+ LOGI("signature is too short for RSA key %zu\n", i);
+ continue;
+ }
+
+ if (!RSA_verify(pKeys[i].rsa, sig_der, RSANUMBYTES,
+ hash, pKeys[i].hash_len)) {
+ LOGI("failed to verify against RSA key %zu\n", i);
+ continue;
+ }
+
+ LOGI("whole-file signature verified against RSA key %zu\n", i);
+ free(sig_der);
+ return VERIFY_SUCCESS;
+ } else if (pKeys[i].key_type == Certificate::EC
+ && pKeys[i].hash_len == SHA256_DIGEST_SIZE) {
+ p256_int r, s;
+ if (!dsa_sig_unpack(sig_der, sig_der_length, &r, &s)) {
+ LOGI("Not a DSA signature block for EC key %zu\n", i);
+ continue;
+ }
+
+ p256_int p256_hash;
+ p256_from_bin(hash, &p256_hash);
+ if (!p256_ecdsa_verify(&(pKeys[i].ec->x), &(pKeys[i].ec->y),
+ &p256_hash, &r, &s)) {
+ LOGI("failed to verify against EC key %zu\n", i);
+ continue;
+ }
+
+ LOGI("whole-file signature verified against EC key %zu\n", i);
+ free(sig_der);
+ return VERIFY_SUCCESS;
+ } else {
+ LOGI("Unknown key type %d\n", pKeys[i].key_type);
+ }
+ LOGI("i: %i, eocd_size: %i, RSANUMBYTES: %i\n", i, eocd_size, RSANUMBYTES);
+ }
+ free(sig_der);
+ LOGE("failed to verify whole-file signature\n");
+ return VERIFY_FAILURE;
+}
+
+// Reads a file containing one or more public keys as produced by
+// DumpPublicKey: this is an RSAPublicKey struct as it would appear
+// as a C source literal, eg:
+//
+// "{64,0xc926ad21,{1795090719,...,-695002876},{-857949815,...,1175080310}}"
+//
+// For key versions newer than the original 2048-bit e=3 keys
+// supported by Android, the string is preceded by a version
+// identifier, eg:
+//
+// "v2 {64,0xc926ad21,{1795090719,...,-695002876},{-857949815,...,1175080310}}"
+//
+// (Note that the braces and commas in this example are actual
+// characters the parser expects to find in the file; the ellipses
+// indicate more numbers omitted from this example.)
+//
+// The file may contain multiple keys in this format, separated by
+// commas. The last key must not be followed by a comma.
+//
+// A Certificate is a pair of an RSAPublicKey and a particular hash
+// (we support SHA-1 and SHA-256; we store the hash length to signify
+// which is being used). The hash used is implied by the version number.
+//
+// 1: 2048-bit RSA key with e=3 and SHA-1 hash
+// 2: 2048-bit RSA key with e=65537 and SHA-1 hash
+// 3: 2048-bit RSA key with e=3 and SHA-256 hash
+// 4: 2048-bit RSA key with e=65537 and SHA-256 hash
+// 5: 256-bit EC key using the NIST P-256 curve parameters and SHA-256 hash
+//
+// Returns NULL if the file failed to parse, or if it contain zero keys.
+Certificate*
+load_keys(const char* filename, int* numKeys) {
+ Certificate* out = NULL;
+ *numKeys = 0;
+
+ FILE* f = fopen(filename, "r");
+ if (f == NULL) {
+ LOGE("opening %s: %s\n", filename, strerror(errno));
+ goto exit;
+ }
+
+ {
+ int i;
+ bool done = false;
+ while (!done) {
+ ++*numKeys;
+ out = (Certificate*)realloc(out, *numKeys * sizeof(Certificate));
+ Certificate* cert = out + (*numKeys - 1);
+ memset(cert, '\0', sizeof(Certificate));
+
+ char start_char;
+ if (fscanf(f, " %c", &start_char) != 1) goto exit;
+ if (start_char == '{') {
+ // a version 1 key has no version specifier.
+ cert->key_type = Certificate::RSA;
+ cert->rsa = (RSAPublicKey*)malloc(sizeof(RSAPublicKey));
+ cert->rsa->exponent = 3;
+ cert->hash_len = SHA_DIGEST_SIZE;
+ } else if (start_char == 'v') {
+ int version;
+ if (fscanf(f, "%d {", &version) != 1) goto exit;
+ switch (version) {
+ case 2:
+ cert->key_type = Certificate::RSA;
+ cert->rsa = (RSAPublicKey*)malloc(sizeof(RSAPublicKey));
+ cert->rsa->exponent = 65537;
+ cert->hash_len = SHA_DIGEST_SIZE;
+ break;
+ case 3:
+ cert->key_type = Certificate::RSA;
+ cert->rsa = (RSAPublicKey*)malloc(sizeof(RSAPublicKey));
+ cert->rsa->exponent = 3;
+ cert->hash_len = SHA256_DIGEST_SIZE;
+ break;
+ case 4:
+ cert->key_type = Certificate::RSA;
+ cert->rsa = (RSAPublicKey*)malloc(sizeof(RSAPublicKey));
+ cert->rsa->exponent = 65537;
+ cert->hash_len = SHA256_DIGEST_SIZE;
+ break;
+ case 5:
+ cert->key_type = Certificate::EC;
+ cert->ec = (ECPublicKey*)calloc(1, sizeof(ECPublicKey));
+ cert->hash_len = SHA256_DIGEST_SIZE;
+ break;
+ default:
+ goto exit;
+ }
+ }
+
+ if (cert->key_type == Certificate::RSA) {
+ RSAPublicKey* key = cert->rsa;
+ if (fscanf(f, " %i , 0x%x , { %u",
+ &(key->len), &(key->n0inv), &(key->n[0])) != 3) {
+ goto exit;
+ }
+ if (key->len != RSANUMWORDS) {
+ LOGE("key length (%d) does not match expected size\n", key->len);
+ goto exit;
+ }
+ for (i = 1; i < key->len; ++i) {
+ if (fscanf(f, " , %u", &(key->n[i])) != 1) goto exit;
+ }
+ if (fscanf(f, " } , { %u", &(key->rr[0])) != 1) goto exit;
+ for (i = 1; i < key->len; ++i) {
+ if (fscanf(f, " , %u", &(key->rr[i])) != 1) goto exit;
+ }
+ fscanf(f, " } } ");
+
+ LOGI("read key e=%d hash=%d\n", key->exponent, cert->hash_len);
+ } else if (cert->key_type == Certificate::EC) {
+ ECPublicKey* key = cert->ec;
+ int key_len;
+ unsigned int byte;
+ uint8_t x_bytes[P256_NBYTES];
+ uint8_t y_bytes[P256_NBYTES];
+ if (fscanf(f, " %i , { %u", &key_len, &byte) != 2) goto exit;
+ if (key_len != P256_NBYTES) {
+ LOGE("Key length (%d) does not match expected size %d\n", key_len, P256_NBYTES);
+ goto exit;
+ }
+ x_bytes[P256_NBYTES - 1] = byte;
+ for (i = P256_NBYTES - 2; i >= 0; --i) {
+ if (fscanf(f, " , %u", &byte) != 1) goto exit;
+ x_bytes[i] = byte;
+ }
+ if (fscanf(f, " } , { %u", &byte) != 1) goto exit;
+ y_bytes[P256_NBYTES - 1] = byte;
+ for (i = P256_NBYTES - 2; i >= 0; --i) {
+ if (fscanf(f, " , %u", &byte) != 1) goto exit;
+ y_bytes[i] = byte;
+ }
+ fscanf(f, " } } ");
+ p256_from_bin(x_bytes, &key->x);
+ p256_from_bin(y_bytes, &key->y);
+ } else {
+ LOGE("Unknown key type %d\n", cert->key_type);
+ goto exit;
+ }
+
+ // if the line ends in a comma, this file has more keys.
+ switch (fgetc(f)) {
+ case ',':
+ // more keys to come.
+ break;
+
+ case EOF:
+ done = true;
+ break;
+
+ default:
+ LOGE("unexpected character between keys\n");
+ goto exit;
+ }
+ }
+ }
+
+ fclose(f);
+ return out;
+
+exit:
+ if (f) fclose(f);
+ free(out);
+ *numKeys = 0;
+ return NULL;
+}
diff --git a/verifier24/verifier.h b/verifier24/verifier.h
new file mode 100644
index 000000000..17ab257ad
--- /dev/null
+++ b/verifier24/verifier.h
@@ -0,0 +1,58 @@
+/*
+ * Copyright (C) 2008 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef _RECOVERY_VERIFIER_H
+#define _RECOVERY_VERIFIER_H
+
+#include "mincrypt/p256.h"
+#include "mincrypt/rsa.h"
+
+#define ASSUMED_UPDATE_BINARY_NAME "META-INF/com/google/android/update-binary"
+
+enum { INSTALL_SUCCESS, INSTALL_ERROR, INSTALL_CORRUPT };
+
+static const float VERIFICATION_PROGRESS_FRACTION = 0.25;
+
+typedef struct {
+ p256_int x;
+ p256_int y;
+} ECPublicKey;
+
+typedef struct {
+ typedef enum {
+ RSA,
+ EC,
+ } KeyType;
+
+ int hash_len; // SHA_DIGEST_SIZE (SHA-1) or SHA256_DIGEST_SIZE (SHA-256)
+ KeyType key_type;
+ RSAPublicKey* rsa;
+ ECPublicKey* ec;
+} Certificate;
+
+/* addr and length define a an update package file that has been
+ * loaded (or mmap'ed, or whatever) into memory. Verify that the file
+ * is signed and the signature matches one of the given keys. Return
+ * one of the constants below.
+ */
+int verify_file(unsigned char* addr, size_t length);
+
+Certificate* load_keys(const char* filename, int* numKeys);
+
+#define VERIFY_SUCCESS 0
+#define VERIFY_FAILURE 1
+
+#endif /* _RECOVERY_VERIFIER_H */