src/security/lib/fcrypto/secret.cc

// Copyright 2017 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.

#include <lib/zircon-internal/debug.h>
#include <stddef.h>
#include <stdint.h>
#include <string.h>
#include <zircon/assert.h>
#include <zircon/errors.h>
#include <zircon/status.h>
#include <zircon/syscalls.h>
#include <zircon/types.h>

#include <explicit-memory/bytes.h>
#include <fbl/algorithm.h>
#include <fbl/alloc_checker.h>
#include <fbl/macros.h>

// See note in //zircon/kernel/lib/crypto/boringssl/BUILD.gn
#define BORINGSSL_NO_CXX
#include <openssl/crypto.h>
#include <openssl/mem.h>

#include "src/security/lib/fcrypto/secret.h"

#define ZXDEBUG 0

namespace crypto {

// Public methods

Secret::Secret() : buf_(nullptr), len_(0) { CRYPTO_library_init(); }

Secret::~Secret() { Clear(); }

Secret::Secret(Secret&& o) noexcept : buf_(std::move(o.buf_)), len_(o.len_) {
  o.buf_ = nullptr;
  o.len_ = 0;
}

Secret& Secret::operator=(Secret&& o) noexcept {
  buf_ = std::move(o.buf_);
  len_ = o.len_;
  o.buf_ = nullptr;
  o.len_ = 0;
  return *this;
}

zx_status_t Secret::Allocate(size_t len, uint8_t** out) {
  ZX_ASSERT(len != 0 && out);

  Clear();
  fbl::AllocChecker ac;
  buf_.reset(new (&ac) uint8_t[len]);
  if (!ac.check()) {
    xprintf("failed to allocate %zu bytes\n", len);
    return ZX_ERR_NO_MEMORY;
  }
  memset(buf_.get(), 0, len);
  len_ = len;

  *out = buf_.get();
  return ZX_OK;
}

zx_status_t Secret::Generate(size_t len) {
  ZX_ASSERT(len != 0);

  uint8_t* tmp = nullptr;
  zx_status_t status = Allocate(len, &tmp);
  if (status != ZX_OK) {
    return status;
  }

  zx_cprng_draw(buf_.get(), len);
  return ZX_OK;
}

void Secret::Clear() {
  if (buf_) {
    mandatory_memset(buf_.get(), 0, len_);
  }
  buf_.reset();
  len_ = 0;
}

}  // namespace crypto