Merge "Unbreak verifying v2 signatures of large APKs." into nyc-dev (481d0f9a) · Commits · e / os / android_frameworks_base

core/java/android/util/apk/ApkSignatureSchemeV2Verifier.java

+376 −188

File changed.

Preview size limit exceeded, changes collapsed.

core/java/android/util/apk/ZipUtils.java

+113 −14

Original line number	Diff line number	Diff line
		@@ -16,13 +16,17 @@

		package android.util.apk;

		import android.util.Pair;

		import java.io.IOException;
		import java.io.RandomAccessFile;
		import java.nio.ByteBuffer;
		import java.nio.ByteOrder;

		/**
		* Assorted ZIP format helpers.
		*
		* <p>NOTE: Most helper methods operating on {@code ByteBuffer} instances except that the byte
		* <p>NOTE: Most helper methods operating on {@code ByteBuffer} instances expect that the byte
		* order of these buffers is little-endian.
		*/
		abstract class ZipUtils {
		@@ -35,9 +39,101 @@ abstract class ZipUtils {
		private static final int ZIP_EOCD_COMMENT_LENGTH_FIELD_OFFSET = 20;

		private static final int ZIP64_EOCD_LOCATOR_SIZE = 20;
		private static final int ZIP64_EOCD_LOCATOR_SIG = 0x07064b50;
		private static final int ZIP64_EOCD_LOCATOR_SIG_REVERSE_BYTE_ORDER = 0x504b0607;

		private static final int UINT32_MAX_VALUE = 0xffff;
		private static final int UINT16_MAX_VALUE = 0xffff;

		/**
		* Returns the ZIP End of Central Directory record of the provided ZIP file.
		*
		* @return contents of the ZIP End of Central Directory record and the record's offset in the
		* file or {@code null} if the file does not contain the record.
		*
		* @throws IOException if an I/O error occurs while reading the file.
		*/
		static Pair<ByteBuffer, Long> findZipEndOfCentralDirectoryRecord(RandomAccessFile zip)
		throws IOException {
		// ZIP End of Central Directory (EOCD) record is located at the very end of the ZIP archive.
		// The record can be identified by its 4-byte signature/magic which is located at the very
		// beginning of the record. A complication is that the record is variable-length because of
		// the comment field.
		// The algorithm for locating the ZIP EOCD record is as follows. We search backwards from
		// end of the buffer for the EOCD record signature. Whenever we find a signature, we check
		// the candidate record's comment length is such that the remainder of the record takes up
		// exactly the remaining bytes in the buffer. The search is bounded because the maximum
		// size of the comment field is 65535 bytes because the field is an unsigned 16-bit number.

		long fileSize = zip.length();
		if (fileSize < ZIP_EOCD_REC_MIN_SIZE) {
		return null;
		}

		// Optimization: 99.99% of APKs have a zero-length comment field in the EoCD record and thus
		// the EoCD record offset is known in advance. Try that offset first to avoid unnecessarily
		// reading more data.
		Pair<ByteBuffer, Long> result = findZipEndOfCentralDirectoryRecord(zip, 0);
		if (result != null) {
		return result;
		}

		// EoCD does not start where we expected it to. Perhaps it contains a non-empty comment
		// field. Expand the search. The maximum size of the comment field in EoCD is 65535 because
		// the comment length field is an unsigned 16-bit number.
		return findZipEndOfCentralDirectoryRecord(zip, UINT16_MAX_VALUE);
		}

		/**
		* Returns the ZIP End of Central Directory record of the provided ZIP file.
		*
		* @param maxCommentSize maximum accepted size (in bytes) of EoCD comment field. The permitted
		* value is from 0 to 65535 inclusive. The smaller the value, the faster this method
		* locates the record, provided its comment field is no longer than this value.
		*
		* @return contents of the ZIP End of Central Directory record and the record's offset in the
		* file or {@code null} if the file does not contain the record.
		*
		* @throws IOException if an I/O error occurs while reading the file.
		*/
		private static Pair<ByteBuffer, Long> findZipEndOfCentralDirectoryRecord(
		RandomAccessFile zip, int maxCommentSize) throws IOException {
		// ZIP End of Central Directory (EOCD) record is located at the very end of the ZIP archive.
		// The record can be identified by its 4-byte signature/magic which is located at the very
		// beginning of the record. A complication is that the record is variable-length because of
		// the comment field.
		// The algorithm for locating the ZIP EOCD record is as follows. We search backwards from
		// end of the buffer for the EOCD record signature. Whenever we find a signature, we check
		// the candidate record's comment length is such that the remainder of the record takes up
		// exactly the remaining bytes in the buffer. The search is bounded because the maximum
		// size of the comment field is 65535 bytes because the field is an unsigned 16-bit number.

		if ((maxCommentSize < 0) \|\| (maxCommentSize > UINT16_MAX_VALUE)) {
		throw new IllegalArgumentException("maxCommentSize: " + maxCommentSize);
		}

		long fileSize = zip.length();
		if (fileSize < ZIP_EOCD_REC_MIN_SIZE) {
		// No space for EoCD record in the file.
		return null;
		}
		// Lower maxCommentSize if the file is too small.
		maxCommentSize = (int) Math.min(maxCommentSize, fileSize - ZIP_EOCD_REC_MIN_SIZE);

		ByteBuffer buf = ByteBuffer.allocate(ZIP_EOCD_REC_MIN_SIZE + maxCommentSize);
		buf.order(ByteOrder.LITTLE_ENDIAN);
		long bufOffsetInFile = fileSize - buf.capacity();
		zip.seek(bufOffsetInFile);
		zip.readFully(buf.array(), buf.arrayOffset(), buf.capacity());
		int eocdOffsetInBuf = findZipEndOfCentralDirectoryRecord(buf);
		if (eocdOffsetInBuf == -1) {
		// No EoCD record found in the buffer
		return null;
		}
		// EoCD found
		buf.position(eocdOffsetInBuf);
		ByteBuffer eocd = buf.slice();
		eocd.order(ByteOrder.LITTLE_ENDIAN);
		return Pair.create(eocd, bufOffsetInFile + eocdOffsetInBuf);
		}

		/**
		* Returns the position at which ZIP End of Central Directory record starts in the provided
		@@ -45,7 +141,7 @@ abstract class ZipUtils {
		*
		* <p>NOTE: Byte order of {@code zipContents} must be little-endian.
		*/
		public static int findZipEndOfCentralDirectoryRecord(ByteBuffer zipContents) {
		private static int findZipEndOfCentralDirectoryRecord(ByteBuffer zipContents) {
		assertByteOrderLittleEndian(zipContents);

		// ZIP End of Central Directory (EOCD) record is located at the very end of the ZIP archive.
		@@ -56,14 +152,13 @@ abstract class ZipUtils {
		// end of the buffer for the EOCD record signature. Whenever we find a signature, we check
		// the candidate record's comment length is such that the remainder of the record takes up
		// exactly the remaining bytes in the buffer. The search is bounded because the maximum
		// size of the comment field is 65535 bytes because the field is an unsigned 32-bit number.
		// size of the comment field is 65535 bytes because the field is an unsigned 16-bit number.

		int archiveSize = zipContents.capacity();
		if (archiveSize < ZIP_EOCD_REC_MIN_SIZE) {
		System.out.println("File size smaller than EOCD min size");
		return -1;
		}
		int maxCommentLength = Math.min(archiveSize - ZIP_EOCD_REC_MIN_SIZE, UINT32_MAX_VALUE);
		int maxCommentLength = Math.min(archiveSize - ZIP_EOCD_REC_MIN_SIZE, UINT16_MAX_VALUE);
		int eocdWithEmptyCommentStartPosition = archiveSize - ZIP_EOCD_REC_MIN_SIZE;
		for (int expectedCommentLength = 0; expectedCommentLength < maxCommentLength;
		expectedCommentLength++) {
		@@ -82,24 +177,28 @@ abstract class ZipUtils {
		}

		/**
		* Returns {@code true} if the provided buffer contains a ZIP64 End of Central Directory
		* Returns {@code true} if the provided file contains a ZIP64 End of Central Directory
		* Locator.
		*
		* <p>NOTE: Byte order of {@code zipContents} must be little-endian.
		* @param zipEndOfCentralDirectoryPosition offset of the ZIP End of Central Directory record
		* in the file.
		*
		* @throws IOException if an I/O error occurs while reading the file.
		*/
		public static final boolean isZip64EndOfCentralDirectoryLocatorPresent(
		ByteBuffer zipContents, int zipEndOfCentralDirectoryPosition) {
		assertByteOrderLittleEndian(zipContents);
		RandomAccessFile zip, long zipEndOfCentralDirectoryPosition) throws IOException {

		// ZIP64 End of Central Directory Locator immediately precedes the ZIP End of Central
		// Directory Record.

		int locatorPosition = zipEndOfCentralDirectoryPosition - ZIP64_EOCD_LOCATOR_SIZE;
		long locatorPosition = zipEndOfCentralDirectoryPosition - ZIP64_EOCD_LOCATOR_SIZE;
		if (locatorPosition < 0) {
		return false;
		}

		return zipContents.getInt(locatorPosition) == ZIP64_EOCD_LOCATOR_SIG;
		zip.seek(locatorPosition);
		// RandomAccessFile.readInt assumes big-endian byte order, but ZIP format uses
		// little-endian.
		return zip.readInt() == ZIP64_EOCD_LOCATOR_SIG_REVERSE_BYTE_ORDER;
		}

		/**