src/tracing/core/packet_stream_validator.cc

/*
 * Copyright (C) 2018 The Android Open Source Project
 *
 * Licensed 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.
 */

#include "src/tracing/core/packet_stream_validator.h"

#include <inttypes.h>
#include <stddef.h>

#include "perfetto/base/logging.h"
#include "perfetto/protozero/proto_utils.h"
#include "perfetto/trace/trusted_packet.pb.h"

namespace perfetto {

// static
bool PacketStreamValidator::Validate(const Slices& slices) {
  SlicedProtobufInputStream stream(&slices);
  size_t size = 0;
  for (const Slice& slice : slices)
    size += slice.size;

  protos::TrustedPacket packet;
  if (!packet.ParseFromBoundedZeroCopyStream(&stream, static_cast<int>(size)))
    return false;

  // Only the service is allowed to fill in the trusted uid.
  if (packet.optional_trusted_uid_case() !=
      protos::TrustedPacket::OPTIONAL_TRUSTED_UID_NOT_SET) {
    return false;
  }

  // Only the service is allowed to fill in the TraceConfig.
  if (packet.has_trace_config())
    return false;

  // Only the service is allowed to fill in the TraceStats.
  if (packet.has_trace_stats())
    return false;

  if (!packet.synchronization_marker().empty())
    return false;

  // We are deliberately not checking for clock_snapshot for the moment. It's
  // unclear if we want to allow producers to snapshot their clocks. Ideally we
  // want a security model where producers can only snapshot their own clocks
  // and not system ones. However, right now, there isn't a compelling need to
  // be so prescriptive.

  return true;
}

}  // namespace perfetto