crash-reporter/ec_collector.cc

// Copyright 2016 The Chromium OS 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 "crash-reporter/ec_collector.h"

#include <string>

#include <base/files/file_util.h>
#include <base/logging.h>
#include <base/strings/stringprintf.h>

#include "crash-reporter/util.h"

using base::FilePath;
using base::StringPiece;
using base::StringPrintf;

namespace {

const char kECDebugFSPath[] = "/sys/kernel/debug/cros_ec/";
const char kECPanicInfo[] = "panicinfo";
const char kECExecName[] = "embedded-controller";

}  // namespace

ECCollector::ECCollector()
    : CrashCollector("ec"), debugfs_path_(kECDebugFSPath) {}

ECCollector::~ECCollector() {}

bool ECCollector::Collect() {
  char data[1024];
  int len;
  FilePath panicinfo_path = debugfs_path_.Append(kECPanicInfo);
  FilePath root_crash_directory;

  if (!base::PathExists(panicinfo_path)) {
    return false;
  }

  len = base::ReadFile(panicinfo_path, data, sizeof(data));

  if (len < 0) {
    PLOG(ERROR) << "Unable to open " << panicinfo_path.value();
    return false;
  }

  if (len <= PANIC_DATA_FLAGS_BYTE) {
    LOG(ERROR) << "EC panicinfo is too short (" << len << " bytes).";
    return false;
  }

  // Check if the EC crash has already been fetched before, in a previous AP
  // boot (EC sets this flag when the AP fetches the panic information).
  if (data[PANIC_DATA_FLAGS_BYTE] & PANIC_DATA_FLAG_OLD_HOSTCMD) {
    LOG(INFO) << "Stale EC crash: already fetched, not reporting.";
    return false;
  }

  std::string reason = "handling";
  bool feedback = true;
  if (util::IsDeveloperImage()) {
    reason = "developer build - always dumping";
    feedback = true;
  } else if (!is_feedback_allowed_function_()) {
    reason = "ignoring - no consent";
    feedback = false;
  }

  LOG(INFO) << "Received crash notification from EC (" << reason << ")";

  if (feedback) {
    if (!GetCreatedCrashDirectoryByEuid(0, &root_crash_directory, nullptr)) {
      return true;
    }

    std::string dump_basename =
        FormatDumpBasename(kECExecName, time(nullptr), 0);
    FilePath ec_crash_path = root_crash_directory.Append(
        StringPrintf("%s.eccrash", dump_basename.c_str()));

    // We must use WriteNewFile instead of base::WriteFile as we
    // do not want to write with root access to a symlink that an attacker
    // might have created.
    if (WriteNewFile(ec_crash_path, data, len) != static_cast<int>(len)) {
      PLOG(ERROR) << "Failed to write EC dump to "
                  << ec_crash_path.value().c_str();
      return true;
    }

    std::string signature = StringPrintf("%s-%08X", kECExecName,
                                         HashString(StringPiece(data, len)));

    /* TODO(drinkcat): Figure out a way to add EC version to metadata. */
    AddCrashMetaData("sig", signature);
    FinishCrash(root_crash_directory.Append(
                    StringPrintf("%s.meta", dump_basename.c_str())),
                kECExecName, ec_crash_path.BaseName().value());

    LOG(INFO) << "Stored EC crash to " << ec_crash_path.value();
  }

  return true;
}