rdblue commented on code in PR #3231: URL: https://github.com/apache/iceberg/pull/3231#discussion_r1278602668
########## core/src/main/java/org/apache/iceberg/encryption/AesGcmInputStream.java: ########## @@ -0,0 +1,274 @@ +/* + * Licensed to the Apache Software Foundation (ASF) under one + * or more contributor license agreements. See the NOTICE file + * distributed with this work for additional information + * regarding copyright ownership. The ASF licenses this file + * to you 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. + */ +package org.apache.iceberg.encryption; + +import java.io.EOFException; +import java.io.IOException; +import java.io.UncheckedIOException; +import java.nio.ByteBuffer; +import java.nio.ByteOrder; +import java.util.Arrays; +import org.apache.iceberg.io.IOUtil; +import org.apache.iceberg.io.SeekableInputStream; +import org.apache.iceberg.relocated.com.google.common.base.Preconditions; + +public class AesGcmInputStream extends SeekableInputStream { + private final SeekableInputStream sourceStream; + private final Ciphers.AesGcmDecryptor gcmDecryptor; + private final byte[] cipherBlockBuffer; + private final int cipherBlockSize; + private final int plainBlockSize; + private final int numberOfBlocks; + private final int lastCipherBlockSize; + private final long plainStreamSize; + private final byte[] fileAADPrefix; + + private long plainStreamPosition; + private int currentBlockIndex; + private int currentOffsetInPlainBlock; + private byte[] currentDecryptedBlock; + private int currentDecryptedBlockIndex; + + AesGcmInputStream( + SeekableInputStream sourceStream, long sourceLength, byte[] aesKey, byte[] fileAADPrefix) + throws IOException { + long netSourceLength = netSourceFileLength(sourceLength); + boolean emptyCipherStream = (0 == netSourceLength); + this.sourceStream = sourceStream; + byte[] headerBytes = new byte[Ciphers.GCM_STREAM_HEADER_LENGTH]; + IOUtil.readFully(sourceStream, headerBytes, 0, headerBytes.length); + byte[] magic = new byte[Ciphers.GCM_STREAM_MAGIC_ARRAY.length]; + System.arraycopy(headerBytes, 0, magic, 0, Ciphers.GCM_STREAM_MAGIC_ARRAY.length); + Preconditions.checkState( + Arrays.equals(Ciphers.GCM_STREAM_MAGIC_ARRAY, magic), + "Cannot open encrypted file, it does not begin with magic string " + + Ciphers.GCM_STREAM_MAGIC_STRING); + this.currentDecryptedBlockIndex = -1; + + if (!emptyCipherStream) { + this.plainStreamPosition = 0; + this.fileAADPrefix = fileAADPrefix; + gcmDecryptor = new Ciphers.AesGcmDecryptor(aesKey); + plainBlockSize = + ByteBuffer.wrap(headerBytes, Ciphers.GCM_STREAM_MAGIC_ARRAY.length, 4) + .order(ByteOrder.LITTLE_ENDIAN) + .getInt(); + Preconditions.checkState(plainBlockSize > 0, "Wrong plainBlockSize " + plainBlockSize); + + Preconditions.checkState( + plainBlockSize == AesGcmOutputStream.plainBlockSize, + "Wrong plainBlockSize " + + plainBlockSize + + ". Only size of " + + AesGcmOutputStream.plainBlockSize + + " is currently supported"); + + cipherBlockSize = plainBlockSize + Ciphers.NONCE_LENGTH + Ciphers.GCM_TAG_LENGTH; + this.cipherBlockBuffer = new byte[cipherBlockSize]; + this.currentBlockIndex = 0; + this.currentOffsetInPlainBlock = 0; + + int numberOfFullBlocks = Math.toIntExact(netSourceLength / cipherBlockSize); + int cipherBytesInLastBlock = + Math.toIntExact(netSourceLength - numberOfFullBlocks * cipherBlockSize); + boolean fullBlocksOnly = (0 == cipherBytesInLastBlock); + numberOfBlocks = fullBlocksOnly ? numberOfFullBlocks : numberOfFullBlocks + 1; + lastCipherBlockSize = fullBlocksOnly ? cipherBlockSize : cipherBytesInLastBlock; // never 0 + plainStreamSize = calculatePlaintextLength(sourceLength, plainBlockSize); + } else { + plainStreamSize = 0; + + gcmDecryptor = null; + cipherBlockBuffer = null; + cipherBlockSize = -1; + plainBlockSize = -1; + numberOfBlocks = -1; + lastCipherBlockSize = -1; + this.fileAADPrefix = null; + } + } + + @Override + public int available() throws IOException { + long maxAvailable = plainStreamSize - plainStreamPosition; + // See InputStream.available contract + if (maxAvailable >= Integer.MAX_VALUE) { + return Integer.MAX_VALUE; + } else { + return (int) maxAvailable; + } + } + + @Override + public int read(byte[] b, int off, int len) throws IOException { + Preconditions.checkState(len >= 0, "Negative read length " + len); + + if (available() <= 0 && len > 0) { + throw new EOFException(); + } + + if (len == 0) { + return 0; + } + + boolean isLastBlockInStream = (currentBlockIndex + 1 == numberOfBlocks); + int resultBufferOffset = off; + int remainingBytesToRead = len; + + while (remainingBytesToRead > 0) { + byte[] plainBlock = decryptNextBlock(isLastBlockInStream); + + int remainingBytesInBlock = plainBlock.length - currentOffsetInPlainBlock; + boolean finishTheBlock = remainingBytesToRead >= remainingBytesInBlock; + int bytesToCopy = finishTheBlock ? remainingBytesInBlock : remainingBytesToRead; + System.arraycopy(plainBlock, currentOffsetInPlainBlock, b, resultBufferOffset, bytesToCopy); + remainingBytesToRead -= bytesToCopy; + resultBufferOffset += bytesToCopy; + currentOffsetInPlainBlock += bytesToCopy; + + boolean endOfStream = isLastBlockInStream && finishTheBlock; + + if (endOfStream) { + break; + } + + if (finishTheBlock) { + currentBlockIndex++; + currentOffsetInPlainBlock = 0; + isLastBlockInStream = (currentBlockIndex + 1 == numberOfBlocks); + } + } + + plainStreamPosition += len - remainingBytesToRead; + return len - remainingBytesToRead; + } + + @Override + public void seek(long newPos) throws IOException { + if (newPos < 0) { + throw new IOException("Negative new position " + newPos); + } else if (newPos > plainStreamSize) { + throw new EOFException( + "New position " + newPos + " exceeds the max stream size " + plainStreamSize); + } + + currentBlockIndex = Math.toIntExact(newPos / plainBlockSize); + currentOffsetInPlainBlock = Math.toIntExact(newPos % plainBlockSize); + plainStreamPosition = newPos; + } + + @Override + public long skip(long n) { + if (n <= 0) { + return 0; + } + + if (plainStreamPosition == plainStreamSize) { + return 0; + } + + long newPosition = plainStreamPosition + n; + + if (newPosition > plainStreamSize) { + long skipped = plainStreamSize - plainStreamPosition; + try { + seek(plainStreamSize); + } catch (IOException e) { + throw new UncheckedIOException(e); + } + return skipped; + } + + try { + seek(newPosition); + } catch (IOException e) { + throw new UncheckedIOException(e); + } + return n; + } + + @Override + public long getPos() throws IOException { + return plainStreamPosition; + } + + @Override + public int read() throws IOException { + throw new UnsupportedOperationException(); + } + + @Override + public void close() throws IOException { + sourceStream.close(); + currentDecryptedBlock = null; + } + + static long calculatePlaintextLength(long sourceLength, int plainBlockSize) { + long netSourceFileLength = netSourceFileLength(sourceLength); + + if (netSourceFileLength == 0) { + return 0; + } + + int cipherBlockSize = plainBlockSize + Ciphers.NONCE_LENGTH + Ciphers.GCM_TAG_LENGTH; + int numberOfFullBlocks = Math.toIntExact(netSourceFileLength / cipherBlockSize); + int cipherBytesInLastBlock = + Math.toIntExact(netSourceFileLength - numberOfFullBlocks * cipherBlockSize); + boolean fullBlocksOnly = (0 == cipherBytesInLastBlock); + int plainBytesInLastBlock = + fullBlocksOnly + ? 0 + : (cipherBytesInLastBlock - Ciphers.NONCE_LENGTH - Ciphers.GCM_TAG_LENGTH); + + return (long) numberOfFullBlocks * plainBlockSize + plainBytesInLastBlock; + } + + private byte[] decryptNextBlock(boolean isLastBlockInStream) throws IOException { + if (currentBlockIndex == currentDecryptedBlockIndex) { + return currentDecryptedBlock; + } + + long blockPositionInStream = blockOffset(currentBlockIndex); + if (sourceStream.getPos() != blockPositionInStream) { + sourceStream.seek(blockPositionInStream); + } + + int currentCipherBlockSize = isLastBlockInStream ? lastCipherBlockSize : cipherBlockSize; + IOUtil.readFully(sourceStream, cipherBlockBuffer, 0, currentCipherBlockSize); + + byte[] aad = Ciphers.streamBlockAAD(fileAADPrefix, currentBlockIndex); + byte[] result = gcmDecryptor.decrypt(cipherBlockBuffer, 0, currentCipherBlockSize, aad); + currentDecryptedBlockIndex = currentBlockIndex; + currentDecryptedBlock = result; + return result; + } + + private long blockOffset(int blockIndex) { + return (long) blockIndex * cipherBlockSize + Ciphers.GCM_STREAM_HEADER_LENGTH; + } + + private static long netSourceFileLength(long sourceFileLength) { Review Comment: I don't think that "net" is clear enough, and I also think that this method is doing too much. A calculation should not include a Precondition check like this because it is surprising. You must know the implementation details of the method to call it properly. I think that the length should be validated in `newStream` when attempting to read the file, and _not_ when calculating the file length for `InputStream.getLength`. I think checking at that point avoids the need to have this method entirely, which avoids the naming problem. The call can simply be `encryptedFileLength - Ciphers.GCM_STREAM_HEADER_LENGTH`. -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: [email protected] For queries about this service, please contact Infrastructure at: [email protected] --------------------------------------------------------------------- To unsubscribe, e-mail: [email protected] For additional commands, e-mail: [email protected]
