You can not select more than 25 topics Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
 
 
 
 
 
 
rocksdb/env/env_encryption.cc

973 lines
35 KiB

// Copyright (c) 2011-present, Facebook, Inc. All rights reserved.
// This source code is licensed under both the GPLv2 (found in the
// COPYING file in the root directory) and Apache 2.0 License
// (found in the LICENSE.Apache file in the root directory).
#ifndef ROCKSDB_LITE
#include "rocksdb/env_encryption.h"
#include <algorithm>
#include <cassert>
#include <cctype>
#include <iostream>
#include "monitoring/perf_context_imp.h"
#include "util/aligned_buffer.h"
#include "util/coding.h"
#include "util/random.h"
#endif
namespace ROCKSDB_NAMESPACE {
#ifndef ROCKSDB_LITE
class EncryptedSequentialFile : public SequentialFile {
private:
std::unique_ptr<SequentialFile> file_;
std::unique_ptr<BlockAccessCipherStream> stream_;
uint64_t offset_;
size_t prefixLength_;
public:
// Default ctor. Given underlying sequential file is supposed to be at
// offset == prefixLength.
EncryptedSequentialFile(SequentialFile* f, BlockAccessCipherStream* s, size_t prefixLength)
: file_(f), stream_(s), offset_(prefixLength), prefixLength_(prefixLength) {
}
// Read up to "n" bytes from the file. "scratch[0..n-1]" may be
// written by this routine. Sets "*result" to the data that was
// read (including if fewer than "n" bytes were successfully read).
// May set "*result" to point at data in "scratch[0..n-1]", so
// "scratch[0..n-1]" must be live when "*result" is used.
// If an error was encountered, returns a non-OK status.
//
// REQUIRES: External synchronization
Status Read(size_t n, Slice* result, char* scratch) override {
assert(scratch);
Status status = file_->Read(n, result, scratch);
if (!status.ok()) {
return status;
}
{
PERF_TIMER_GUARD(decrypt_data_nanos);
status = stream_->Decrypt(offset_, (char*)result->data(), result->size());
}
offset_ += result->size(); // We've already ready data from disk, so update
// offset_ even if decryption fails.
return status;
}
// Skip "n" bytes from the file. This is guaranteed to be no
// slower that reading the same data, but may be faster.
//
// If end of file is reached, skipping will stop at the end of the
// file, and Skip will return OK.
//
// REQUIRES: External synchronization
Status Skip(uint64_t n) override {
auto status = file_->Skip(n);
if (!status.ok()) {
return status;
}
offset_ += n;
return status;
}
// Indicates the upper layers if the current SequentialFile implementation
// uses direct IO.
bool use_direct_io() const override { return file_->use_direct_io(); }
// Use the returned alignment value to allocate
// aligned buffer for Direct I/O
size_t GetRequiredBufferAlignment() const override {
return file_->GetRequiredBufferAlignment();
}
// Remove any kind of caching of data from the offset to offset+length
// of this file. If the length is 0, then it refers to the end of file.
// If the system is not caching the file contents, then this is a noop.
Status InvalidateCache(size_t offset, size_t length) override {
return file_->InvalidateCache(offset + prefixLength_, length);
}
// Positioned Read for direct I/O
// If Direct I/O enabled, offset, n, and scratch should be properly aligned
Status PositionedRead(uint64_t offset, size_t n, Slice* result,
char* scratch) override {
assert(scratch);
offset += prefixLength_; // Skip prefix
auto status = file_->PositionedRead(offset, n, result, scratch);
if (!status.ok()) {
return status;
}
offset_ = offset + result->size();
{
PERF_TIMER_GUARD(decrypt_data_nanos);
status = stream_->Decrypt(offset, (char*)result->data(), result->size());
}
return status;
}
};
// A file abstraction for randomly reading the contents of a file.
class EncryptedRandomAccessFile : public RandomAccessFile {
private:
std::unique_ptr<RandomAccessFile> file_;
std::unique_ptr<BlockAccessCipherStream> stream_;
size_t prefixLength_;
public:
EncryptedRandomAccessFile(RandomAccessFile* f, BlockAccessCipherStream* s, size_t prefixLength)
: file_(f), stream_(s), prefixLength_(prefixLength) { }
// Read up to "n" bytes from the file starting at "offset".
// "scratch[0..n-1]" may be written by this routine. Sets "*result"
// to the data that was read (including if fewer than "n" bytes were
// successfully read). May set "*result" to point at data in
// "scratch[0..n-1]", so "scratch[0..n-1]" must be live when
// "*result" is used. If an error was encountered, returns a non-OK
// status.
//
// Safe for concurrent use by multiple threads.
// If Direct I/O enabled, offset, n, and scratch should be aligned properly.
Status Read(uint64_t offset, size_t n, Slice* result,
char* scratch) const override {
assert(scratch);
offset += prefixLength_;
auto status = file_->Read(offset, n, result, scratch);
if (!status.ok()) {
return status;
}
{
PERF_TIMER_GUARD(decrypt_data_nanos);
status = stream_->Decrypt(offset, (char*)result->data(), result->size());
}
return status;
}
// Readahead the file starting from offset by n bytes for caching.
Status Prefetch(uint64_t offset, size_t n) override {
//return Status::OK();
return file_->Prefetch(offset + prefixLength_, n);
}
// Tries to get an unique ID for this file that will be the same each time
// the file is opened (and will stay the same while the file is open).
// Furthermore, it tries to make this ID at most "max_size" bytes. If such an
// ID can be created this function returns the length of the ID and places it
// in "id"; otherwise, this function returns 0, in which case "id"
// may not have been modified.
//
// This function guarantees, for IDs from a given environment, two unique ids
// cannot be made equal to each other by adding arbitrary bytes to one of
// them. That is, no unique ID is the prefix of another.
//
// This function guarantees that the returned ID will not be interpretable as
// a single varint.
//
// Note: these IDs are only valid for the duration of the process.
size_t GetUniqueId(char* id, size_t max_size) const override {
return file_->GetUniqueId(id, max_size);
};
void Hint(AccessPattern pattern) override { file_->Hint(pattern); }
// Indicates the upper layers if the current RandomAccessFile implementation
// uses direct IO.
bool use_direct_io() const override { return file_->use_direct_io(); }
// Use the returned alignment value to allocate
// aligned buffer for Direct I/O
size_t GetRequiredBufferAlignment() const override {
return file_->GetRequiredBufferAlignment();
}
// Remove any kind of caching of data from the offset to offset+length
// of this file. If the length is 0, then it refers to the end of file.
// If the system is not caching the file contents, then this is a noop.
Status InvalidateCache(size_t offset, size_t length) override {
return file_->InvalidateCache(offset + prefixLength_, length);
}
};
// A file abstraction for sequential writing. The implementation
// must provide buffering since callers may append small fragments
// at a time to the file.
class EncryptedWritableFile : public WritableFileWrapper {
private:
std::unique_ptr<WritableFile> file_;
std::unique_ptr<BlockAccessCipherStream> stream_;
size_t prefixLength_;
public:
// Default ctor. Prefix is assumed to be written already.
EncryptedWritableFile(WritableFile* f, BlockAccessCipherStream* s, size_t prefixLength)
: WritableFileWrapper(f), file_(f), stream_(s), prefixLength_(prefixLength) { }
Status Append(const Slice& data) override {
AlignedBuffer buf;
Status status;
Slice dataToAppend(data);
if (data.size() > 0) {
auto offset = file_->GetFileSize(); // size including prefix
// Encrypt in cloned buffer
buf.Alignment(GetRequiredBufferAlignment());
buf.AllocateNewBuffer(data.size());
// TODO (sagar0): Modify AlignedBuffer.Append to allow doing a memmove
// so that the next two lines can be replaced with buf.Append().
memmove(buf.BufferStart(), data.data(), data.size());
buf.Size(data.size());
{
PERF_TIMER_GUARD(encrypt_data_nanos);
status = stream_->Encrypt(offset, buf.BufferStart(), buf.CurrentSize());
}
if (!status.ok()) {
return status;
}
dataToAppend = Slice(buf.BufferStart(), buf.CurrentSize());
}
status = file_->Append(dataToAppend);
if (!status.ok()) {
return status;
}
return status;
}
Status PositionedAppend(const Slice& data, uint64_t offset) override {
AlignedBuffer buf;
Status status;
Slice dataToAppend(data);
offset += prefixLength_;
if (data.size() > 0) {
// Encrypt in cloned buffer
buf.Alignment(GetRequiredBufferAlignment());
buf.AllocateNewBuffer(data.size());
memmove(buf.BufferStart(), data.data(), data.size());
buf.Size(data.size());
{
PERF_TIMER_GUARD(encrypt_data_nanos);
status = stream_->Encrypt(offset, buf.BufferStart(), buf.CurrentSize());
}
if (!status.ok()) {
return status;
}
dataToAppend = Slice(buf.BufferStart(), buf.CurrentSize());
}
status = file_->PositionedAppend(dataToAppend, offset);
if (!status.ok()) {
return status;
}
return status;
}
// Indicates the upper layers if the current WritableFile implementation
// uses direct IO.
bool use_direct_io() const override { return file_->use_direct_io(); }
// Use the returned alignment value to allocate
// aligned buffer for Direct I/O
size_t GetRequiredBufferAlignment() const override {
return file_->GetRequiredBufferAlignment();
}
/*
* Get the size of valid data in the file.
*/
uint64_t GetFileSize() override {
return file_->GetFileSize() - prefixLength_;
}
// Truncate is necessary to trim the file to the correct size
// before closing. It is not always possible to keep track of the file
// size due to whole pages writes. The behavior is undefined if called
// with other writes to follow.
Status Truncate(uint64_t size) override {
return file_->Truncate(size + prefixLength_);
}
// Remove any kind of caching of data from the offset to offset+length
// of this file. If the length is 0, then it refers to the end of file.
// If the system is not caching the file contents, then this is a noop.
// This call has no effect on dirty pages in the cache.
Status InvalidateCache(size_t offset, size_t length) override {
return file_->InvalidateCache(offset + prefixLength_, length);
}
// Sync a file range with disk.
// offset is the starting byte of the file range to be synchronized.
// nbytes specifies the length of the range to be synchronized.
// This asks the OS to initiate flushing the cached data to disk,
// without waiting for completion.
// Default implementation does nothing.
Status RangeSync(uint64_t offset, uint64_t nbytes) override {
return file_->RangeSync(offset + prefixLength_, nbytes);
}
// PrepareWrite performs any necessary preparation for a write
// before the write actually occurs. This allows for pre-allocation
// of space on devices where it can result in less file
// fragmentation and/or less waste from over-zealous filesystem
// pre-allocation.
void PrepareWrite(size_t offset, size_t len) override {
file_->PrepareWrite(offset + prefixLength_, len);
}
// Pre-allocates space for a file.
Status Allocate(uint64_t offset, uint64_t len) override {
return file_->Allocate(offset + prefixLength_, len);
}
};
// A file abstraction for random reading and writing.
class EncryptedRandomRWFile : public RandomRWFile {
private:
std::unique_ptr<RandomRWFile> file_;
std::unique_ptr<BlockAccessCipherStream> stream_;
size_t prefixLength_;
public:
EncryptedRandomRWFile(RandomRWFile* f, BlockAccessCipherStream* s, size_t prefixLength)
: file_(f), stream_(s), prefixLength_(prefixLength) {}
// Indicates if the class makes use of direct I/O
// If false you must pass aligned buffer to Write()
bool use_direct_io() const override { return file_->use_direct_io(); }
// Use the returned alignment value to allocate
// aligned buffer for Direct I/O
size_t GetRequiredBufferAlignment() const override {
return file_->GetRequiredBufferAlignment();
}
// Write bytes in `data` at offset `offset`, Returns Status::OK() on success.
// Pass aligned buffer when use_direct_io() returns true.
Status Write(uint64_t offset, const Slice& data) override {
AlignedBuffer buf;
Status status;
Slice dataToWrite(data);
offset += prefixLength_;
if (data.size() > 0) {
// Encrypt in cloned buffer
buf.Alignment(GetRequiredBufferAlignment());
buf.AllocateNewBuffer(data.size());
memmove(buf.BufferStart(), data.data(), data.size());
buf.Size(data.size());
{
PERF_TIMER_GUARD(encrypt_data_nanos);
status = stream_->Encrypt(offset, buf.BufferStart(), buf.CurrentSize());
}
if (!status.ok()) {
return status;
}
dataToWrite = Slice(buf.BufferStart(), buf.CurrentSize());
}
status = file_->Write(offset, dataToWrite);
return status;
}
// Read up to `n` bytes starting from offset `offset` and store them in
// result, provided `scratch` size should be at least `n`.
// Returns Status::OK() on success.
Status Read(uint64_t offset, size_t n, Slice* result,
char* scratch) const override {
assert(scratch);
offset += prefixLength_;
auto status = file_->Read(offset, n, result, scratch);
if (!status.ok()) {
return status;
}
{
PERF_TIMER_GUARD(decrypt_data_nanos);
status = stream_->Decrypt(offset, (char*)result->data(), result->size());
}
return status;
}
Status Flush() override { return file_->Flush(); }
Status Sync() override { return file_->Sync(); }
Status Fsync() override { return file_->Fsync(); }
Status Close() override { return file_->Close(); }
};
// EncryptedEnv implements an Env wrapper that adds encryption to files stored on disk.
class EncryptedEnv : public EnvWrapper {
public:
EncryptedEnv(Env* base_env, EncryptionProvider *provider)
: EnvWrapper(base_env) {
provider_ = provider;
}
// NewSequentialFile opens a file for sequential reading.
Status NewSequentialFile(const std::string& fname,
std::unique_ptr<SequentialFile>* result,
const EnvOptions& options) override {
result->reset();
if (options.use_mmap_reads) {
return Status::InvalidArgument();
}
// Open file using underlying Env implementation
std::unique_ptr<SequentialFile> underlying;
auto status = EnvWrapper::NewSequentialFile(fname, &underlying, options);
if (!status.ok()) {
return status;
}
// Read prefix (if needed)
AlignedBuffer prefixBuf;
Slice prefixSlice;
size_t prefixLength = provider_->GetPrefixLength();
if (prefixLength > 0) {
// Read prefix
prefixBuf.Alignment(underlying->GetRequiredBufferAlignment());
prefixBuf.AllocateNewBuffer(prefixLength);
status = underlying->Read(prefixLength, &prefixSlice, prefixBuf.BufferStart());
if (!status.ok()) {
return status;
}
prefixBuf.Size(prefixLength);
}
// Create cipher stream
std::unique_ptr<BlockAccessCipherStream> stream;
status = provider_->CreateCipherStream(fname, options, prefixSlice, &stream);
if (!status.ok()) {
return status;
}
(*result) = std::unique_ptr<SequentialFile>(new EncryptedSequentialFile(underlying.release(), stream.release(), prefixLength));
return Status::OK();
}
// NewRandomAccessFile opens a file for random read access.
Status NewRandomAccessFile(const std::string& fname,
std::unique_ptr<RandomAccessFile>* result,
const EnvOptions& options) override {
result->reset();
if (options.use_mmap_reads) {
return Status::InvalidArgument();
}
// Open file using underlying Env implementation
std::unique_ptr<RandomAccessFile> underlying;
auto status = EnvWrapper::NewRandomAccessFile(fname, &underlying, options);
if (!status.ok()) {
return status;
}
// Read prefix (if needed)
AlignedBuffer prefixBuf;
Slice prefixSlice;
size_t prefixLength = provider_->GetPrefixLength();
if (prefixLength > 0) {
// Read prefix
prefixBuf.Alignment(underlying->GetRequiredBufferAlignment());
prefixBuf.AllocateNewBuffer(prefixLength);
status = underlying->Read(0, prefixLength, &prefixSlice, prefixBuf.BufferStart());
if (!status.ok()) {
return status;
}
prefixBuf.Size(prefixLength);
}
// Create cipher stream
std::unique_ptr<BlockAccessCipherStream> stream;
status = provider_->CreateCipherStream(fname, options, prefixSlice, &stream);
if (!status.ok()) {
return status;
}
(*result) = std::unique_ptr<RandomAccessFile>(new EncryptedRandomAccessFile(underlying.release(), stream.release(), prefixLength));
return Status::OK();
}
// NewWritableFile opens a file for sequential writing.
Status NewWritableFile(const std::string& fname,
std::unique_ptr<WritableFile>* result,
const EnvOptions& options) override {
result->reset();
if (options.use_mmap_writes) {
return Status::InvalidArgument();
}
// Open file using underlying Env implementation
std::unique_ptr<WritableFile> underlying;
Status status = EnvWrapper::NewWritableFile(fname, &underlying, options);
if (!status.ok()) {
return status;
}
// Initialize & write prefix (if needed)
AlignedBuffer prefixBuf;
Slice prefixSlice;
size_t prefixLength = provider_->GetPrefixLength();
if (prefixLength > 0) {
// Initialize prefix
prefixBuf.Alignment(underlying->GetRequiredBufferAlignment());
prefixBuf.AllocateNewBuffer(prefixLength);
provider_->CreateNewPrefix(fname, prefixBuf.BufferStart(), prefixLength);
prefixBuf.Size(prefixLength);
prefixSlice = Slice(prefixBuf.BufferStart(), prefixBuf.CurrentSize());
// Write prefix
status = underlying->Append(prefixSlice);
if (!status.ok()) {
return status;
}
}
// Create cipher stream
std::unique_ptr<BlockAccessCipherStream> stream;
status = provider_->CreateCipherStream(fname, options, prefixSlice, &stream);
if (!status.ok()) {
return status;
}
(*result) = std::unique_ptr<WritableFile>(new EncryptedWritableFile(underlying.release(), stream.release(), prefixLength));
return Status::OK();
}
// Create an object that writes to a new file with the specified
// name. Deletes any existing file with the same name and creates a
// new file. On success, stores a pointer to the new file in
// *result and returns OK. On failure stores nullptr in *result and
// returns non-OK.
//
// The returned file will only be accessed by one thread at a time.
Status ReopenWritableFile(const std::string& fname,
std::unique_ptr<WritableFile>* result,
const EnvOptions& options) override {
result->reset();
if (options.use_mmap_writes) {
return Status::InvalidArgument();
}
// Open file using underlying Env implementation
std::unique_ptr<WritableFile> underlying;
Status status = EnvWrapper::ReopenWritableFile(fname, &underlying, options);
if (!status.ok()) {
return status;
}
// Initialize & write prefix (if needed)
AlignedBuffer prefixBuf;
Slice prefixSlice;
size_t prefixLength = provider_->GetPrefixLength();
if (prefixLength > 0) {
// Initialize prefix
prefixBuf.Alignment(underlying->GetRequiredBufferAlignment());
prefixBuf.AllocateNewBuffer(prefixLength);
provider_->CreateNewPrefix(fname, prefixBuf.BufferStart(), prefixLength);
prefixBuf.Size(prefixLength);
prefixSlice = Slice(prefixBuf.BufferStart(), prefixBuf.CurrentSize());
// Write prefix
status = underlying->Append(prefixSlice);
if (!status.ok()) {
return status;
}
}
// Create cipher stream
std::unique_ptr<BlockAccessCipherStream> stream;
status = provider_->CreateCipherStream(fname, options, prefixSlice, &stream);
if (!status.ok()) {
return status;
}
(*result) = std::unique_ptr<WritableFile>(new EncryptedWritableFile(underlying.release(), stream.release(), prefixLength));
return Status::OK();
}
// Reuse an existing file by renaming it and opening it as writable.
Status ReuseWritableFile(const std::string& fname,
const std::string& old_fname,
std::unique_ptr<WritableFile>* result,
const EnvOptions& options) override {
result->reset();
if (options.use_mmap_writes) {
return Status::InvalidArgument();
}
// Open file using underlying Env implementation
std::unique_ptr<WritableFile> underlying;
Status status = EnvWrapper::ReuseWritableFile(fname, old_fname, &underlying, options);
if (!status.ok()) {
return status;
}
// Initialize & write prefix (if needed)
AlignedBuffer prefixBuf;
Slice prefixSlice;
size_t prefixLength = provider_->GetPrefixLength();
if (prefixLength > 0) {
// Initialize prefix
prefixBuf.Alignment(underlying->GetRequiredBufferAlignment());
prefixBuf.AllocateNewBuffer(prefixLength);
provider_->CreateNewPrefix(fname, prefixBuf.BufferStart(), prefixLength);
prefixBuf.Size(prefixLength);
prefixSlice = Slice(prefixBuf.BufferStart(), prefixBuf.CurrentSize());
// Write prefix
status = underlying->Append(prefixSlice);
if (!status.ok()) {
return status;
}
}
// Create cipher stream
std::unique_ptr<BlockAccessCipherStream> stream;
status = provider_->CreateCipherStream(fname, options, prefixSlice, &stream);
if (!status.ok()) {
return status;
}
(*result) = std::unique_ptr<WritableFile>(new EncryptedWritableFile(underlying.release(), stream.release(), prefixLength));
return Status::OK();
}
// Open `fname` for random read and write, if file doesn't exist the file
// will be created. On success, stores a pointer to the new file in
// *result and returns OK. On failure returns non-OK.
//
// The returned file will only be accessed by one thread at a time.
Status NewRandomRWFile(const std::string& fname,
std::unique_ptr<RandomRWFile>* result,
const EnvOptions& options) override {
result->reset();
if (options.use_mmap_reads || options.use_mmap_writes) {
return Status::InvalidArgument();
}
// Check file exists
bool isNewFile = !FileExists(fname).ok();
// Open file using underlying Env implementation
std::unique_ptr<RandomRWFile> underlying;
Status status = EnvWrapper::NewRandomRWFile(fname, &underlying, options);
if (!status.ok()) {
return status;
}
// Read or Initialize & write prefix (if needed)
AlignedBuffer prefixBuf;
Slice prefixSlice;
size_t prefixLength = provider_->GetPrefixLength();
if (prefixLength > 0) {
prefixBuf.Alignment(underlying->GetRequiredBufferAlignment());
prefixBuf.AllocateNewBuffer(prefixLength);
if (!isNewFile) {
// File already exists, read prefix
status = underlying->Read(0, prefixLength, &prefixSlice, prefixBuf.BufferStart());
if (!status.ok()) {
return status;
}
prefixBuf.Size(prefixLength);
} else {
// File is new, initialize & write prefix
provider_->CreateNewPrefix(fname, prefixBuf.BufferStart(), prefixLength);
prefixBuf.Size(prefixLength);
prefixSlice = Slice(prefixBuf.BufferStart(), prefixBuf.CurrentSize());
// Write prefix
status = underlying->Write(0, prefixSlice);
if (!status.ok()) {
return status;
}
}
}
// Create cipher stream
std::unique_ptr<BlockAccessCipherStream> stream;
status = provider_->CreateCipherStream(fname, options, prefixSlice, &stream);
if (!status.ok()) {
return status;
}
(*result) = std::unique_ptr<RandomRWFile>(new EncryptedRandomRWFile(underlying.release(), stream.release(), prefixLength));
return Status::OK();
}
// Store in *result the attributes of the children of the specified directory.
// In case the implementation lists the directory prior to iterating the files
// and files are concurrently deleted, the deleted files will be omitted from
// result.
// The name attributes are relative to "dir".
// Original contents of *results are dropped.
// Returns OK if "dir" exists and "*result" contains its children.
// NotFound if "dir" does not exist, the calling process does not have
// permission to access "dir", or if "dir" is invalid.
// IOError if an IO Error was encountered
Status GetChildrenFileAttributes(
const std::string& dir, std::vector<FileAttributes>* result) override {
auto status = EnvWrapper::GetChildrenFileAttributes(dir, result);
if (!status.ok()) {
return status;
}
size_t prefixLength = provider_->GetPrefixLength();
for (auto it = std::begin(*result); it!=std::end(*result); ++it) {
assert(it->size_bytes >= prefixLength);
it->size_bytes -= prefixLength;
}
return Status::OK();
}
// Store the size of fname in *file_size.
Status GetFileSize(const std::string& fname, uint64_t* file_size) override {
auto status = EnvWrapper::GetFileSize(fname, file_size);
if (!status.ok()) {
return status;
}
size_t prefixLength = provider_->GetPrefixLength();
assert(*file_size >= prefixLength);
*file_size -= prefixLength;
return Status::OK();
}
private:
EncryptionProvider *provider_;
};
// Returns an Env that encrypts data when stored on disk and decrypts data when
// read from disk.
Env* NewEncryptedEnv(Env* base_env, EncryptionProvider* provider) {
return new EncryptedEnv(base_env, provider);
}
// Encrypt one or more (partial) blocks of data at the file offset.
// Length of data is given in dataSize.
Status BlockAccessCipherStream::Encrypt(uint64_t fileOffset, char *data, size_t dataSize) {
// Calculate block index
auto blockSize = BlockSize();
uint64_t blockIndex = fileOffset / blockSize;
size_t blockOffset = fileOffset % blockSize;
std::unique_ptr<char[]> blockBuffer;
std::string scratch;
AllocateScratch(scratch);
// Encrypt individual blocks.
while (1) {
char *block = data;
size_t n = std::min(dataSize, blockSize - blockOffset);
if (n != blockSize) {
// We're not encrypting a full block.
// Copy data to blockBuffer
if (!blockBuffer.get()) {
// Allocate buffer
blockBuffer = std::unique_ptr<char[]>(new char[blockSize]);
}
block = blockBuffer.get();
// Copy plain data to block buffer
memmove(block + blockOffset, data, n);
}
auto status = EncryptBlock(blockIndex, block, (char*)scratch.data());
if (!status.ok()) {
return status;
}
if (block != data) {
// Copy encrypted data back to `data`.
memmove(data, block + blockOffset, n);
}
dataSize -= n;
if (dataSize == 0) {
return Status::OK();
}
data += n;
blockOffset = 0;
blockIndex++;
}
}
// Decrypt one or more (partial) blocks of data at the file offset.
// Length of data is given in dataSize.
Status BlockAccessCipherStream::Decrypt(uint64_t fileOffset, char *data, size_t dataSize) {
// Calculate block index
auto blockSize = BlockSize();
uint64_t blockIndex = fileOffset / blockSize;
size_t blockOffset = fileOffset % blockSize;
std::unique_ptr<char[]> blockBuffer;
std::string scratch;
AllocateScratch(scratch);
// Decrypt individual blocks.
while (1) {
char *block = data;
size_t n = std::min(dataSize, blockSize - blockOffset);
if (n != blockSize) {
// We're not decrypting a full block.
// Copy data to blockBuffer
if (!blockBuffer.get()) {
// Allocate buffer
blockBuffer = std::unique_ptr<char[]>(new char[blockSize]);
}
block = blockBuffer.get();
// Copy encrypted data to block buffer
memmove(block + blockOffset, data, n);
}
auto status = DecryptBlock(blockIndex, block, (char*)scratch.data());
if (!status.ok()) {
return status;
}
if (block != data) {
// Copy decrypted data back to `data`.
memmove(data, block + blockOffset, n);
}
// Simply decrementing dataSize by n could cause it to underflow,
// which will very likely make it read over the original bounds later
assert(dataSize >= n);
if (dataSize < n) {
return Status::Corruption("Cannot decrypt data at given offset");
}
dataSize -= n;
if (dataSize == 0) {
return Status::OK();
}
data += n;
blockOffset = 0;
blockIndex++;
}
}
// Encrypt a block of data.
// Length of data is equal to BlockSize().
Status ROT13BlockCipher::Encrypt(char *data) {
for (size_t i = 0; i < blockSize_; ++i) {
data[i] += 13;
}
return Status::OK();
}
// Decrypt a block of data.
// Length of data is equal to BlockSize().
Status ROT13BlockCipher::Decrypt(char *data) {
return Encrypt(data);
}
// Allocate scratch space which is passed to EncryptBlock/DecryptBlock.
void CTRCipherStream::AllocateScratch(std::string& scratch) {
auto blockSize = cipher_.BlockSize();
scratch.reserve(blockSize);
}
// Encrypt a block of data at the given block index.
// Length of data is equal to BlockSize();
Status CTRCipherStream::EncryptBlock(uint64_t blockIndex, char *data, char* scratch) {
// Create nonce + counter
auto blockSize = cipher_.BlockSize();
memmove(scratch, iv_.data(), blockSize);
EncodeFixed64(scratch, blockIndex + initialCounter_);
// Encrypt nonce+counter
auto status = cipher_.Encrypt(scratch);
if (!status.ok()) {
return status;
}
// XOR data with ciphertext.
for (size_t i = 0; i < blockSize; i++) {
data[i] = data[i] ^ scratch[i];
}
return Status::OK();
}
// Decrypt a block of data at the given block index.
// Length of data is equal to BlockSize();
Status CTRCipherStream::DecryptBlock(uint64_t blockIndex, char *data, char* scratch) {
// For CTR decryption & encryption are the same
return EncryptBlock(blockIndex, data, scratch);
}
// GetPrefixLength returns the length of the prefix that is added to every file
// and used for storing encryption options.
// For optimal performance, the prefix length should be a multiple of
// the page size.
size_t CTREncryptionProvider::GetPrefixLength() {
return defaultPrefixLength;
}
// decodeCTRParameters decodes the initial counter & IV from the given
// (plain text) prefix.
static void decodeCTRParameters(const char *prefix, size_t blockSize, uint64_t &initialCounter, Slice &iv) {
// First block contains 64-bit initial counter
initialCounter = DecodeFixed64(prefix);
// Second block contains IV
iv = Slice(prefix + blockSize, blockSize);
}
// CreateNewPrefix initialized an allocated block of prefix memory
// for a new file.
Status CTREncryptionProvider::CreateNewPrefix(const std::string& /*fname*/,
char* prefix,
size_t prefixLength) {
// Create & seed rnd.
Random rnd((uint32_t)Env::Default()->NowMicros());
// Fill entire prefix block with random values.
for (size_t i = 0; i < prefixLength; i++) {
prefix[i] = rnd.Uniform(256) & 0xFF;
}
// Take random data to extract initial counter & IV
auto blockSize = cipher_.BlockSize();
uint64_t initialCounter;
Slice prefixIV;
decodeCTRParameters(prefix, blockSize, initialCounter, prefixIV);
// Now populate the rest of the prefix, starting from the third block.
PopulateSecretPrefixPart(prefix + (2 * blockSize), prefixLength - (2 * blockSize), blockSize);
// Encrypt the prefix, starting from block 2 (leave block 0, 1 with initial
// counter & IV unencrypted)
CTRCipherStream cipherStream(cipher_, prefixIV.data(), initialCounter);
Status status;
{
PERF_TIMER_GUARD(encrypt_data_nanos);
status = cipherStream.Encrypt(0, prefix + (2 * blockSize),
prefixLength - (2 * blockSize));
}
if (!status.ok()) {
return status;
}
return Status::OK();
}
// PopulateSecretPrefixPart initializes the data into a new prefix block
// in plain text.
// Returns the amount of space (starting from the start of the prefix)
// that has been initialized.
size_t CTREncryptionProvider::PopulateSecretPrefixPart(char* /*prefix*/,
size_t /*prefixLength*/,
size_t /*blockSize*/) {
// Nothing to do here, put in custom data in override when needed.
return 0;
}
Status CTREncryptionProvider::CreateCipherStream(
const std::string& fname, const EnvOptions& options, Slice& prefix,
std::unique_ptr<BlockAccessCipherStream>* result) {
// Read plain text part of prefix.
auto blockSize = cipher_.BlockSize();
uint64_t initialCounter;
Slice iv;
decodeCTRParameters(prefix.data(), blockSize, initialCounter, iv);
// If the prefix is smaller than twice the block size, we would below read a
// very large chunk of the file (and very likely read over the bounds)
assert(prefix.size() >= 2 * blockSize);
if (prefix.size() < 2 * blockSize) {
return Status::Corruption("Unable to read from file " + fname +
": read attempt would read beyond file bounds");
}
// Decrypt the encrypted part of the prefix, starting from block 2 (block 0, 1
// with initial counter & IV are unencrypted)
CTRCipherStream cipherStream(cipher_, iv.data(), initialCounter);
Status status;
{
PERF_TIMER_GUARD(decrypt_data_nanos);
status = cipherStream.Decrypt(0, (char*)prefix.data() + (2 * blockSize),
prefix.size() - (2 * blockSize));
}
if (!status.ok()) {
return status;
}
// Create cipher stream
return CreateCipherStreamFromPrefix(fname, options, initialCounter, iv, prefix, result);
}
// CreateCipherStreamFromPrefix creates a block access cipher stream for a file given
// given name and options. The given prefix is already decrypted.
Status CTREncryptionProvider::CreateCipherStreamFromPrefix(
const std::string& /*fname*/, const EnvOptions& /*options*/,
uint64_t initialCounter, const Slice& iv, const Slice& /*prefix*/,
std::unique_ptr<BlockAccessCipherStream>* result) {
(*result) = std::unique_ptr<BlockAccessCipherStream>(
new CTRCipherStream(cipher_, iv.data(), initialCounter));
return Status::OK();
}
#endif // ROCKSDB_LITE
} // namespace ROCKSDB_NAMESPACE