src/security/zxcrypt/fdio-volume.h

// Copyright 2019 The Fuchsia Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef SRC_SECURITY_ZXCRYPT_FDIO_VOLUME_H_
#define SRC_SECURITY_ZXCRYPT_FDIO_VOLUME_H_

#include <lib/fdio/fdio.h>
#include <lib/zx/channel.h>

#include <memory>

#include <fbl/string.h>
#include <fbl/unique_fd.h>

#include "src/security/fcrypto/secret.h"
#include "src/security/zxcrypt/volume.h"

namespace zxcrypt {

// |zxcrypt::FdioVolume| is a zxcrypt volume which does IO via a file descriptor
// to an underlying block device without any support from the zxcrypt driver
// implementation.  It can be used on the host to prepare zxcrypt images, and is
// often more convenient for testing.
class __EXPORT FdioVolume final : public Volume {
 public:
  explicit FdioVolume(fbl::unique_fd&& block_dev_fd);

  // Creates a new zxcrypt volume associated with the given file descriptor,
  // |block_dev_fd|, and returns it via |out|, if provided.  This will format
  // the block device as zxcrypt using the given |key|, which will be
  // associated with key slot 0.  This method takes ownership of
  // |block_dev_fd|.  Note that |key| is not strengthened
  // and MUST have cryptographic key length of at least 128 bits.
  static zx_status_t Create(fbl::unique_fd block_dev_fd, const crypto::Secret& key,
                            std::unique_ptr<FdioVolume>* out = nullptr);

  // Opens a zxcrypt volume on the block device described by |block_dev_fd|
  // using the |key| corresponding to given key |slot|.  This method takes
  // ownership of |block_dev_fd|.  Note that |key| is not strengthened and MUST
  // have cryptographic key length of at least 128 bits.  This is a convenience
  // method that calls |Init()| and then |FdioVolume::Unlock()|.
  static zx_status_t Unlock(fbl::unique_fd block_dev_fd, const crypto::Secret& key, key_slot_t slot,
                            std::unique_ptr<FdioVolume>* out);

  // Returns a new volume object corresponding to the block device given by
  // |block_dev_fd| and populated with the block and FVM information.
  static zx_status_t Init(fbl::unique_fd block_dev_fd, std::unique_ptr<FdioVolume>* out = nullptr);

  // Opens a zxcrypt volume on the block device described by |fd| using the |key| corresponding to
  // given key |slot|.
  zx_status_t Unlock(const crypto::Secret& key, key_slot_t slot);

  // Adds a given |key| to the given key |slot|.  This key can then be used to |Open| the
  // zxcrypt device.  This method can only be called if the volume belongs to libzxcrypt.
  zx_status_t Enroll(const crypto::Secret& key, key_slot_t slot);

  // Removes the root key in the given key |slot|.  This key can no longer be used to |Open| the
  // zxcrypt device.  This method can only be called if the volume belongs to libzxcrypt.
  zx_status_t Revoke(key_slot_t slot);

 private:
  friend class testing::TestDevice;

  // Retrieves the block and FVM information and adjusts it
  zx_status_t Init();

  zx_status_t GetBlockInfo(BlockInfo* out);
  zx_status_t GetFvmSliceSize(uint64_t* out);
  zx_status_t DoBlockFvmVsliceQuery(uint64_t vslice_start, SliceRegion ranges[MAX_SLICE_REGIONS],
                                    uint64_t* slice_count);
  zx_status_t DoBlockFvmExtend(uint64_t start_slice, uint64_t slice_count);

  // Reads a block from the current offset on the underlying device.
  zx_status_t Read();

  // Writes a block to the current offset on the underlying device.
  zx_status_t Write();

  // Flushes all pending writes to the underlying device.
  zx_status_t Flush();

  // The underlying block device, accessed over FDIO
  fbl::unique_fd block_dev_fd_;
};

}  // namespace zxcrypt

#endif  // SRC_SECURITY_ZXCRYPT_FDIO_VOLUME_H_