362 lines
12 KiB
C
362 lines
12 KiB
C
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/*
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* Copyright (C) 2008 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#include "common.h"
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#include "verifier.h"
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#include "minzip/Zip.h"
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#include "mincrypt/rsa.h"
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#include "mincrypt/sha.h"
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#include <netinet/in.h> /* required for resolv.h */
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#include <resolv.h> /* for base64 codec */
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#include <string.h>
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/* Return an allocated buffer with the contents of a zip file entry. */
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static char *slurpEntry(const ZipArchive *pArchive, const ZipEntry *pEntry) {
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if (!mzIsZipEntryIntact(pArchive, pEntry)) {
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UnterminatedString fn = mzGetZipEntryFileName(pEntry);
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LOGE("Invalid %.*s\n", fn.len, fn.str);
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return NULL;
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}
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int len = mzGetZipEntryUncompLen(pEntry);
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char *buf = malloc(len + 1);
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if (buf == NULL) {
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UnterminatedString fn = mzGetZipEntryFileName(pEntry);
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LOGE("Can't allocate %d bytes for %.*s\n", len, fn.len, fn.str);
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return NULL;
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}
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if (!mzReadZipEntry(pArchive, pEntry, buf, len)) {
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UnterminatedString fn = mzGetZipEntryFileName(pEntry);
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LOGE("Can't read %.*s\n", fn.len, fn.str);
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free(buf);
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return NULL;
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}
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buf[len] = '\0';
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return buf;
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}
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struct DigestContext {
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SHA_CTX digest;
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unsigned *doneBytes;
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unsigned totalBytes;
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};
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/* mzProcessZipEntryContents callback to update an SHA-1 hash context. */
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static bool updateHash(const unsigned char *data, int dataLen, void *cookie) {
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struct DigestContext *context = (struct DigestContext *) cookie;
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SHA_update(&context->digest, data, dataLen);
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if (context->doneBytes != NULL) {
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*context->doneBytes += dataLen;
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if (context->totalBytes > 0) {
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ui_set_progress(*context->doneBytes * 1.0 / context->totalBytes);
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}
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}
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return true;
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}
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/* Get the SHA-1 digest of a zip file entry. */
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static bool digestEntry(const ZipArchive *pArchive, const ZipEntry *pEntry,
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unsigned *doneBytes, unsigned totalBytes,
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uint8_t digest[SHA_DIGEST_SIZE]) {
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struct DigestContext context;
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SHA_init(&context.digest);
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context.doneBytes = doneBytes;
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context.totalBytes = totalBytes;
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if (!mzProcessZipEntryContents(pArchive, pEntry, updateHash, &context)) {
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UnterminatedString fn = mzGetZipEntryFileName(pEntry);
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LOGE("Can't digest %.*s\n", fn.len, fn.str);
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return false;
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}
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memcpy(digest, SHA_final(&context.digest), SHA_DIGEST_SIZE);
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#ifdef LOG_VERBOSE
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UnterminatedString fn = mzGetZipEntryFileName(pEntry);
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char base64[SHA_DIGEST_SIZE * 3];
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b64_ntop(digest, SHA_DIGEST_SIZE, base64, sizeof(base64));
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LOGV("sha1(%.*s) = %s\n", fn.len, fn.str, base64);
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#endif
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return true;
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}
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/* Find a /META-INF/xxx.SF signature file signed by a matching xxx.RSA file. */
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static const ZipEntry *verifySignature(const ZipArchive *pArchive,
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const RSAPublicKey *pKeys, unsigned int numKeys) {
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static const char prefix[] = "META-INF/";
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static const char rsa[] = ".RSA", sf[] = ".SF";
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unsigned int i, j;
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for (i = 0; i < mzZipEntryCount(pArchive); ++i) {
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const ZipEntry *rsaEntry = mzGetZipEntryAt(pArchive, i);
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UnterminatedString rsaName = mzGetZipEntryFileName(rsaEntry);
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int rsaLen = mzGetZipEntryUncompLen(rsaEntry);
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if (rsaLen >= RSANUMBYTES && rsaName.len > sizeof(prefix) &&
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!strncmp(rsaName.str, prefix, sizeof(prefix) - 1) &&
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!strncmp(rsaName.str + rsaName.len - sizeof(rsa) + 1,
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rsa, sizeof(rsa) - 1)) {
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char *sfName = malloc(rsaName.len - sizeof(rsa) + sizeof(sf) + 1);
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if (sfName == NULL) {
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LOGE("Can't allocate %d bytes for filename\n", rsaName.len);
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continue;
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}
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/* Replace .RSA with .SF */
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strncpy(sfName, rsaName.str, rsaName.len - sizeof(rsa) + 1);
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strcpy(sfName + rsaName.len - sizeof(rsa) + 1, sf);
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const ZipEntry *sfEntry = mzFindZipEntry(pArchive, sfName);
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if (sfEntry == NULL) {
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LOGW("Missing signature file %s\n", sfName);
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free(sfName);
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continue;
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}
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free(sfName);
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uint8_t sfDigest[SHA_DIGEST_SIZE];
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if (!digestEntry(pArchive, sfEntry, NULL, 0, sfDigest)) continue;
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char *rsaBuf = slurpEntry(pArchive, rsaEntry);
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if (rsaBuf == NULL) continue;
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/* Try to verify the signature with all the keys. */
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uint8_t *sig = (uint8_t *) rsaBuf + rsaLen - RSANUMBYTES;
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for (j = 0; j < numKeys; ++j) {
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if (RSA_verify(&pKeys[j], sig, RSANUMBYTES, sfDigest)) {
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free(rsaBuf);
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LOGI("Verified %.*s\n", rsaName.len, rsaName.str);
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return sfEntry;
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}
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}
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free(rsaBuf);
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LOGW("Can't verify %.*s\n", rsaName.len, rsaName.str);
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}
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}
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LOGE("No signature (%d files)\n", mzZipEntryCount(pArchive));
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return NULL;
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}
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/* Verify /META-INF/MANIFEST.MF against the digest in a signature file. */
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static const ZipEntry *verifyManifest(const ZipArchive *pArchive,
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const ZipEntry *sfEntry) {
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static const char prefix[] = "SHA1-Digest-Manifest: ", eol[] = "\r\n";
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uint8_t expected[SHA_DIGEST_SIZE + 3], actual[SHA_DIGEST_SIZE];
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char *sfBuf = slurpEntry(pArchive, sfEntry);
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if (sfBuf == NULL) return NULL;
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char *line, *save;
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for (line = strtok_r(sfBuf, eol, &save); line != NULL;
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line = strtok_r(NULL, eol, &save)) {
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if (!strncasecmp(prefix, line, sizeof(prefix) - 1)) {
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UnterminatedString fn = mzGetZipEntryFileName(sfEntry);
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const char *digest = line + sizeof(prefix) - 1;
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int n = b64_pton(digest, expected, sizeof(expected));
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if (n != SHA_DIGEST_SIZE) {
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LOGE("Invalid base64 in %.*s: %s (%d)\n",
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fn.len, fn.str, digest, n);
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line = NULL;
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}
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break;
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}
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}
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free(sfBuf);
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if (line == NULL) {
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LOGE("No digest manifest in signature file\n");
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return false;
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}
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const char *mfName = "META-INF/MANIFEST.MF";
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const ZipEntry *mfEntry = mzFindZipEntry(pArchive, mfName);
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if (mfEntry == NULL) {
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LOGE("No manifest file %s\n", mfName);
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return NULL;
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}
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if (!digestEntry(pArchive, mfEntry, NULL, 0, actual)) return NULL;
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if (memcmp(expected, actual, SHA_DIGEST_SIZE)) {
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UnterminatedString fn = mzGetZipEntryFileName(sfEntry);
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LOGE("Wrong digest for %s in %.*s\n", mfName, fn.len, fn.str);
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return NULL;
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}
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LOGI("Verified %s\n", mfName);
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return mfEntry;
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}
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/* Verify all the files in a Zip archive against the manifest. */
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static bool verifyArchive(const ZipArchive *pArchive, const ZipEntry *mfEntry) {
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static const char namePrefix[] = "Name: ";
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static const char contPrefix[] = " "; // Continuation of the filename
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static const char digestPrefix[] = "SHA1-Digest: ";
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static const char eol[] = "\r\n";
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char *mfBuf = slurpEntry(pArchive, mfEntry);
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if (mfBuf == NULL) return false;
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/* we're using calloc() here, so the initial state of the array is false */
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bool *unverified = (bool *) calloc(mzZipEntryCount(pArchive), sizeof(bool));
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if (unverified == NULL) {
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LOGE("Can't allocate valid flags\n");
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free(mfBuf);
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return false;
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}
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/* Mark all the files in the archive that need to be verified.
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* As we scan the manifest and check signatures, we'll unset these flags.
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* At the end, we'll make sure that all the flags are unset.
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*/
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unsigned i, totalBytes = 0;
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for (i = 0; i < mzZipEntryCount(pArchive); ++i) {
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const ZipEntry *entry = mzGetZipEntryAt(pArchive, i);
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UnterminatedString fn = mzGetZipEntryFileName(entry);
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int len = mzGetZipEntryUncompLen(entry);
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// Don't validate: directories, the manifest, *.RSA, and *.SF.
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if (entry == mfEntry) {
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LOGV("Skipping manifest %.*s\n", fn.len, fn.str);
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} else if (fn.len > 0 && fn.str[fn.len-1] == '/' && len == 0) {
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LOGV("Skipping directory %.*s\n", fn.len, fn.str);
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} else if (!strncasecmp(fn.str, "META-INF/", 9) && (
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!strncasecmp(fn.str + fn.len - 4, ".RSA", 4) ||
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!strncasecmp(fn.str + fn.len - 3, ".SF", 3))) {
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LOGV("Skipping signature %.*s\n", fn.len, fn.str);
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} else {
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unverified[i] = true;
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totalBytes += len;
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}
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}
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unsigned doneBytes = 0;
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char *line, *save, *name = NULL;
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for (line = strtok_r(mfBuf, eol, &save); line != NULL;
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line = strtok_r(NULL, eol, &save)) {
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if (!strncasecmp(line, namePrefix, sizeof(namePrefix) - 1)) {
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// "Name:" introducing a new stanza
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if (name != NULL) {
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LOGE("No digest:\n %s\n", name);
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break;
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}
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name = strdup(line + sizeof(namePrefix) - 1);
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if (name == NULL) {
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LOGE("Can't copy filename in %s\n", line);
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break;
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}
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} else if (!strncasecmp(line, contPrefix, sizeof(contPrefix) - 1)) {
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// Continuing a long name (nothing else should be continued)
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const char *tail = line + sizeof(contPrefix) - 1;
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if (name == NULL) {
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LOGE("Unexpected continuation:\n %s\n", tail);
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}
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char *concat;
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if (asprintf(&concat, "%s%s", name, tail) < 0) {
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LOGE("Can't append continuation %s\n", tail);
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break;
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}
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free(name);
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name = concat;
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} else if (!strncasecmp(line, digestPrefix, sizeof(digestPrefix) - 1)) {
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// "Digest:" supplying a hash code for the current stanza
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const char *base64 = line + sizeof(digestPrefix) - 1;
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if (name == NULL) {
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LOGE("Unexpected digest:\n %s\n", base64);
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break;
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}
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const ZipEntry *entry = mzFindZipEntry(pArchive, name);
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if (entry == NULL) {
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LOGE("Missing file:\n %s\n", name);
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break;
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}
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if (!mzIsZipEntryIntact(pArchive, entry)) {
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LOGE("Corrupt file:\n %s\n", name);
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break;
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}
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if (!unverified[mzGetZipEntryIndex(pArchive, entry)]) {
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LOGE("Unexpected file:\n %s\n", name);
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break;
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}
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uint8_t expected[SHA_DIGEST_SIZE + 3], actual[SHA_DIGEST_SIZE];
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int n = b64_pton(base64, expected, sizeof(expected));
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if (n != SHA_DIGEST_SIZE) {
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LOGE("Invalid base64:\n %s\n %s\n", name, base64);
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break;
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}
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if (!digestEntry(pArchive, entry, &doneBytes, totalBytes, actual) ||
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memcmp(expected, actual, SHA_DIGEST_SIZE) != 0) {
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LOGE("Wrong digest:\n %s\n", name);
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break;
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}
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LOGI("Verified %s\n", name);
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unverified[mzGetZipEntryIndex(pArchive, entry)] = false;
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free(name);
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name = NULL;
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}
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}
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if (name != NULL) free(name);
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free(mfBuf);
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for (i = 0; i < mzZipEntryCount(pArchive) && !unverified[i]; ++i) ;
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free(unverified);
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// This means we didn't get to the end of the manifest successfully.
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if (line != NULL) return false;
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if (i < mzZipEntryCount(pArchive)) {
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const ZipEntry *entry = mzGetZipEntryAt(pArchive, i);
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UnterminatedString fn = mzGetZipEntryFileName(entry);
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LOGE("No digest for %.*s\n", fn.len, fn.str);
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return false;
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}
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return true;
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}
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bool verify_jar_signature(const ZipArchive *pArchive,
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const RSAPublicKey *pKeys, int numKeys) {
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const ZipEntry *sfEntry = verifySignature(pArchive, pKeys, numKeys);
|
||
|
|
if (sfEntry == NULL) return false;
|
||
|
|
|
||
|
|
const ZipEntry *mfEntry = verifyManifest(pArchive, sfEntry);
|
||
|
|
if (mfEntry == NULL) return false;
|
||
|
|
|
||
|
|
return verifyArchive(pArchive, mfEntry);
|
||
|
|
}
|