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authorEthan Yonker <dees_troy@teamw.in>2014-11-21 20:54:27 +0100
committerEthan Yonker <dees_troy@teamw.in>2014-12-02 17:34:15 +0100
commit75bf041a8ad75f8fc9bba69e937e12b129338a4c (patch)
tree9a3202b8c06e075e1749a44948a3a3f184edf95e /verifierold.cpp
parentTWRP MTP: make sure inotify_fd is set (diff)
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-rw-r--r--verifierold.cpp344
1 files changed, 344 insertions, 0 deletions
diff --git a/verifierold.cpp b/verifierold.cpp
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+++ b/verifierold.cpp
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+/*
+ * 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 "common.h"
+#include "verifierold.h"
+#include "ui.h"
+
+#include "mincrypt/rsa.h"
+#include "mincrypt/sha.h"
+#include "mincrypt/sha256.h"
+
+#include <string.h>
+#include <stdio.h>
+#include <errno.h>
+
+//extern RecoveryUI* ui;
+
+#define PUBLIC_KEYS_FILE "/res/keys"
+
+// 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(const char* path) {
+ //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);
+
+ FILE* f = fopen(path, "rb");
+ if (f == NULL) {
+ LOGE("failed to open %s (%s)\n", path, strerror(errno));
+ return VERIFY_FAILURE;
+ }
+
+ // 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 (fseek(f, -FOOTER_SIZE, SEEK_END) != 0) {
+ LOGE("failed to seek in %s (%s)\n", path, strerror(errno));
+ fclose(f);
+ return VERIFY_FAILURE;
+ }
+
+ unsigned char footer[FOOTER_SIZE];
+ if (fread(footer, 1, FOOTER_SIZE, f) != FOOTER_SIZE) {
+ LOGE("failed to read footer from %s (%s)\n", path, strerror(errno));
+ fclose(f);
+ return VERIFY_FAILURE;
+ }
+
+ if (footer[2] != 0xff || footer[3] != 0xff) {
+ LOGE("footer is wrong\n");
+ fclose(f);
+ return VERIFY_FAILURE;
+ }
+
+ size_t comment_size = footer[4] + (footer[5] << 8);
+ size_t signature_start = footer[0] + (footer[1] << 8);
+ LOGI("comment is %d bytes; signature %d bytes from end\n",
+ comment_size, signature_start);
+
+ if (signature_start - FOOTER_SIZE < RSANUMBYTES) {
+ // "signature" block isn't big enough to contain an RSA block.
+ LOGE("signature is too short\n");
+ fclose(f);
+ 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 (fseek(f, -eocd_size, SEEK_END) != 0) {
+ LOGE("failed to seek in %s (%s)\n", path, strerror(errno));
+ fclose(f);
+ 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 = ftell(f) + EOCD_HEADER_SIZE - 2;
+
+ unsigned char* eocd = (unsigned char*)malloc(eocd_size);
+ if (eocd == NULL) {
+ LOGE("malloc for EOCD record failed\n");
+ fclose(f);
+ return VERIFY_FAILURE;
+ }
+ if (fread(eocd, 1, eocd_size, f) != eocd_size) {
+ LOGE("failed to read eocd from %s (%s)\n", path, strerror(errno));
+ fclose(f);
+ return VERIFY_FAILURE;
+ }
+
+ // 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");
+ fclose(f);
+ 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");
+ fclose(f);
+ 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);
+ unsigned char* buffer = (unsigned char*)malloc(BUFFER_SIZE);
+ if (buffer == NULL) {
+ LOGE("failed to alloc memory for sha1 buffer\n");
+ fclose(f);
+ return VERIFY_FAILURE;
+ }
+
+ double frac = -1.0;
+ size_t so_far = 0;
+ fseek(f, 0, SEEK_SET);
+ while (so_far < signed_len) {
+ size_t size = BUFFER_SIZE;
+ if (signed_len - so_far < size) size = signed_len - so_far;
+ if (fread(buffer, 1, size, f) != size) {
+ LOGE("failed to read data from %s (%s)\n", path, strerror(errno));
+ fclose(f);
+ return VERIFY_FAILURE;
+ }
+ if (need_sha1) SHA_update(&sha1_ctx, buffer, size);
+ if (need_sha256) SHA256_update(&sha256_ctx, buffer, size);
+ so_far += size;
+ double f = so_far / (double)signed_len;
+ if (f > frac + 0.02 || size == so_far) {
+ //ui->SetProgress(f);
+ frac = f;
+ }
+ }
+ fclose(f);
+ free(buffer);
+
+ const uint8_t* sha1 = SHA_final(&sha1_ctx);
+ const uint8_t* sha256 = SHA256_final(&sha256_ctx);
+
+ 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 (RSA_verify(pKeys[i].public_key, eocd + eocd_size - 6 - RSANUMBYTES,
+ RSANUMBYTES, hash, pKeys[i].hash_len)) {
+ LOGI("whole-file signature verified against key %d\n", i);
+ free(eocd);
+ return VERIFY_SUCCESS;
+ } else {
+ LOGI("failed to verify against key %d\n", i);
+ }
+ LOGI("i: %i, eocd_size: %i, RSANUMBYTES: %i\n", i, eocd_size, RSANUMBYTES);
+ }
+ free(eocd);
+ 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
+//
+// 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);
+ cert->public_key = (RSAPublicKey*)malloc(sizeof(RSAPublicKey));
+
+ char start_char;
+ if (fscanf(f, " %c", &start_char) != 1) goto exit;
+ if (start_char == '{') {
+ // a version 1 key has no version specifier.
+ cert->public_key->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->public_key->exponent = 65537;
+ cert->hash_len = SHA_DIGEST_SIZE;
+ break;
+ case 3:
+ cert->public_key->exponent = 3;
+ cert->hash_len = SHA256_DIGEST_SIZE;
+ break;
+ case 4:
+ cert->public_key->exponent = 65537;
+ cert->hash_len = SHA256_DIGEST_SIZE;
+ break;
+ default:
+ goto exit;
+ }
+ }
+
+ RSAPublicKey* key = cert->public_key;
+ 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, " } } ");
+
+ // 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;
+ }
+ LOGI("read key e=%d hash=%d\n", key->exponent, cert->hash_len);
+ }
+ }
+
+ fclose(f);
+ return out;
+
+exit:
+ if (f) fclose(f);
+ free(out);
+ *numKeys = 0;
+ return NULL;
+}