// Copyright (c) 2012 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/crash_collector.h"

#include <dirent.h>
#include <fcntl.h>  // For file creation modes.
#include <inttypes.h>
#include <linux/limits.h>  // PATH_MAX
#include <pwd.h>  // For struct passwd.
#include <sys/types.h>  // for mode_t.
#include <sys/wait.h>  // For waitpid.
#include <unistd.h>  // For execv and fork.

#include <set>
#include <vector>

#include <pcrecpp.h>

#include <base/files/file_util.h>
#include <base/logging.h>
#include <base/posix/eintr_wrapper.h>
#include <base/scoped_clear_errno.h>
#include <base/strings/string_split.h>
#include <base/strings/string_util.h>
#include <base/strings/stringprintf.h>
#include <brillo/cryptohome.h>
#include <brillo/key_value_store.h>
#include <brillo/process.h>

namespace {

const char kCollectChromeFile[] =
    "/mnt/stateful_partition/etc/collect_chrome_crashes";
const char kCrashTestInProgressPath[] = "/tmp/crash-test-in-progress";
const char kDefaultLogConfig[] = "/etc/crash_reporter_logs.conf";
const char kDefaultUserName[] = "chronos";
const char kLeaveCoreFile[] = "/root/.leave_core";
const char kLsbRelease[] = "/etc/lsb-release";
const char kShellPath[] = "/bin/sh";
const char kSystemCrashPath[] = "/var/spool/crash";
const char kUploadVarPrefix[] = "upload_var_";
const char kUploadTextPrefix[] = "upload_text_";
const char kUploadFilePrefix[] = "upload_file_";

// Key of the lsb-release entry containing the OS version.
const char kLsbVersionKey[] = "CHROMEOS_RELEASE_VERSION";

// Normally this path is not used.  Unfortunately, there are a few edge cases
// where we need this.  Any process that runs as kDefaultUserName that crashes
// is consider a "user crash".  That includes the initial Chrome browser that
// runs the login screen.  If that blows up, there is no logged in user yet,
// so there is no per-user dir for us to stash things in.  Instead we fallback
// to this path as it is at least encrypted on a per-system basis.
//
// This also comes up when running autotests.  The GUI is sitting at the login
// screen while tests are sshing in, changing users, and triggering crashes as
// the user (purposefully).
const char kFallbackUserCrashPath[] = "/home/chronos/crash";

// Directory mode of the user crash spool directory.
const mode_t kUserCrashPathMode = 0755;

// Directory mode of the system crash spool directory.
const mode_t kSystemCrashPathMode = 01755;

const uid_t kRootGroup = 0;

// Buffer size for reading a log into memory.
constexpr size_t kMaxLogSize = 1024 * 1024;

const char kGzipPath[] = "/bin/gzip";

}  // namespace

const char * const CrashCollector::kUnknownVersion = "unknown";

// Maximum crash reports per crash spool directory.  Note that this is
// a separate maximum from the maximum rate at which we upload these
// diagnostics.  The higher this rate is, the more space we allow for
// core files, minidumps, and kcrash logs, and equivalently the more
// processor and I/O bandwidth we dedicate to handling these crashes when
// many occur at once.  Also note that if core files are configured to
// be left on the file system, we stop adding crashes when either the
// number of core files or minidumps reaches this number.
const int CrashCollector::kMaxCrashDirectorySize = 32;

const uid_t CrashCollector::kRootUid = 0;

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

CrashCollector::CrashCollector()
    : CrashCollector(false) {
}

CrashCollector::CrashCollector(bool force_user_crash_dir)
    : lsb_release_(kLsbRelease),
      system_crash_path_(kSystemCrashPath),
      log_config_path_(kDefaultLogConfig),
      max_log_size_(kMaxLogSize),
      force_user_crash_dir_(force_user_crash_dir) {
}

CrashCollector::~CrashCollector() {
  if (bus_)
    bus_->ShutdownAndBlock();
}

void CrashCollector::Initialize(
    CrashCollector::CountCrashFunction count_crash_function,
    CrashCollector::IsFeedbackAllowedFunction is_feedback_allowed_function) {
  CHECK(count_crash_function);
  CHECK(is_feedback_allowed_function);

  count_crash_function_ = count_crash_function;
  is_feedback_allowed_function_ = is_feedback_allowed_function;
}

void CrashCollector::SetUpDBus() {
  if (bus_)
    return;

  dbus::Bus::Options options;
  options.bus_type = dbus::Bus::SYSTEM;

  bus_ = new dbus::Bus(options);
  CHECK(bus_->Connect());

  session_manager_proxy_.reset(
      new org::chromium::SessionManagerInterfaceProxy(bus_));
}

int CrashCollector::WriteNewFile(const FilePath &filename,
                                 const char *data,
                                 int size) {
  int fd = HANDLE_EINTR(open(filename.value().c_str(),
                             O_CREAT | O_WRONLY | O_TRUNC | O_EXCL, 0666));
  if (fd < 0) {
    return -1;
  }

  int rv = base::WriteFileDescriptor(fd, data, size) ? size : -1;
  base::ScopedClearErrno restore_error;
  IGNORE_EINTR(close(fd));
  return rv;
}

std::string CrashCollector::Sanitize(const std::string &name) {
  // Make sure the sanitized name does not include any periods.
  // The logic in crash_sender relies on this.
  std::string result = name;
  for (size_t i = 0; i < name.size(); ++i) {
    if (!isalnum(result[i]) && result[i] != '_')
      result[i] = '_';
  }
  return result;
}

void CrashCollector::StripSensitiveData(std::string *contents) {
  // At the moment, the only sensitive data we strip is MAC addresses.

  // Get rid of things that look like MAC addresses, since they could possibly
  // give information about where someone has been.  This is strings that look
  // like this: 11:22:33:44:55:66
  // Complications:
  // - Within a given log, we want to be able to tell when the same MAC
  //   was used more than once.  Thus, we'll consistently replace the first
  //   MAC found with 00:00:00:00:00:01, the second with ...:02, etc.
  // - ACPI commands look like MAC addresses.  We'll specifically avoid getting
  //   rid of those.
  std::ostringstream result;
  std::string pre_mac_str;
  std::string mac_str;
  std::map<std::string, std::string> mac_map;
  pcrecpp::StringPiece input(*contents);

  // This RE will find the next MAC address and can return us the data preceding
  // the MAC and the MAC itself.
  pcrecpp::RE mac_re("(.*?)("
                     "[0-9a-fA-F][0-9a-fA-F]:"
                     "[0-9a-fA-F][0-9a-fA-F]:"
                     "[0-9a-fA-F][0-9a-fA-F]:"
                     "[0-9a-fA-F][0-9a-fA-F]:"
                     "[0-9a-fA-F][0-9a-fA-F]:"
                     "[0-9a-fA-F][0-9a-fA-F])",
                     pcrecpp::RE_Options()
                       .set_multiline(true)
                       .set_dotall(true));

  // This RE will identify when the 'pre_mac_str' shows that the MAC address
  // was really an ACPI cmd.  The full string looks like this:
  //   ata1.00: ACPI cmd ef/10:03:00:00:00:a0 (SET FEATURES) filtered out
  pcrecpp::RE acpi_re("ACPI cmd ef/$",
                      pcrecpp::RE_Options()
                        .set_multiline(true)
                        .set_dotall(true));

  // Keep consuming, building up a result string as we go.
  while (mac_re.Consume(&input, &pre_mac_str, &mac_str)) {
    if (acpi_re.PartialMatch(pre_mac_str)) {
      // We really saw an ACPI command; add to result w/ no stripping.
      result << pre_mac_str << mac_str;
    } else {
      // Found a MAC address; look up in our hash for the mapping.
      std::string replacement_mac = mac_map[mac_str];
      if (replacement_mac == "") {
        // It wasn't present, so build up a replacement string.
        int mac_id = mac_map.size();

        // Handle up to 2^32 unique MAC address; overkill, but doesn't hurt.
        replacement_mac = StringPrintf("00:00:%02x:%02x:%02x:%02x",
                                       (mac_id & 0xff000000) >> 24,
                                       (mac_id & 0x00ff0000) >> 16,
                                       (mac_id & 0x0000ff00) >> 8,
                                       (mac_id & 0x000000ff));
        mac_map[mac_str] = replacement_mac;
      }

      // Dump the string before the MAC and the fake MAC address into result.
      result << pre_mac_str << replacement_mac;
    }
  }

  // One last bit of data might still be in the input.
  result << input;

  // We'll just assign right back to |contents|.
  *contents = result.str();
}

std::string CrashCollector::FormatDumpBasename(const std::string &exec_name,
                                               time_t timestamp,
                                               pid_t pid) {
  struct tm tm;
  localtime_r(&timestamp, &tm);
  std::string sanitized_exec_name = Sanitize(exec_name);
  return StringPrintf("%s.%04d%02d%02d.%02d%02d%02d.%d",
                      sanitized_exec_name.c_str(),
                      tm.tm_year + 1900,
                      tm.tm_mon + 1,
                      tm.tm_mday,
                      tm.tm_hour,
                      tm.tm_min,
                      tm.tm_sec,
                      pid);
}

FilePath CrashCollector::GetCrashPath(const FilePath &crash_directory,
                                      const std::string &basename,
                                      const std::string &extension) {
  return crash_directory.Append(StringPrintf("%s.%s",
                                             basename.c_str(),
                                             extension.c_str()));
}

bool CrashCollector::GetActiveUserSessions(
    std::map<std::string, std::string> *sessions) {
  brillo::ErrorPtr error;
  SetUpDBus();
  session_manager_proxy_->RetrieveActiveSessions(sessions, &error);

  if (error) {
    LOG(ERROR) << "Error calling D-Bus proxy call to interface "
               << "'" << session_manager_proxy_->GetObjectPath().value() << "':"
               << error->GetMessage();
    return false;
  }

  return true;
}

FilePath CrashCollector::GetUserCrashPath() {
  // In this multiprofile world, there is no one-specific user dir anymore.
  // Ask the session manager for the active ones, then just run with the
  // first result we get back.
  FilePath user_path = FilePath(kFallbackUserCrashPath);
  std::map<std::string, std::string> active_sessions;
  if (!GetActiveUserSessions(&active_sessions) || active_sessions.empty()) {
    LOG(ERROR) << "Could not get active user sessions, using default.";
    return user_path;
  }

  user_path = brillo::cryptohome::home::GetHashedUserPath(
      active_sessions.begin()->second).Append("crash");

  return user_path;
}

FilePath CrashCollector::GetCrashDirectoryInfo(
    uid_t process_euid,
    uid_t default_user_id,
    gid_t default_user_group,
    mode_t *mode,
    uid_t *directory_owner,
    gid_t *directory_group) {
  // TODO(mkrebs): This can go away once Chrome crashes are handled
  // normally (see crosbug.com/5872).
  // Check if the user crash directory should be used.  If we are
  // collecting chrome crashes during autotesting, we want to put them in
  // the system crash directory so they are outside the cryptohome -- in
  // case we are being run during logout (see crosbug.com/18637).
  if ((process_euid == default_user_id && IsUserSpecificDirectoryEnabled()) ||
      force_user_crash_dir_) {
    *mode = kUserCrashPathMode;
    *directory_owner = default_user_id;
    *directory_group = default_user_group;
    return GetUserCrashPath();
  } else {
    *mode = kSystemCrashPathMode;
    *directory_owner = kRootUid;
    *directory_group = kRootGroup;
    return system_crash_path_;
  }
}

bool CrashCollector::GetUserInfoFromName(const std::string &name,
                                         uid_t *uid,
                                         gid_t *gid) {
  char storage[256];
  struct passwd passwd_storage;
  struct passwd *passwd_result = nullptr;

  if (getpwnam_r(name.c_str(), &passwd_storage, storage, sizeof(storage),
                 &passwd_result) != 0 || passwd_result == nullptr) {
    LOG(ERROR) << "Cannot find user named " << name;
    return false;
  }

  *uid = passwd_result->pw_uid;
  *gid = passwd_result->pw_gid;
  return true;
}

bool CrashCollector::GetCreatedCrashDirectoryByEuid(uid_t euid,
                                                    FilePath *crash_directory,
                                                    bool *out_of_capacity) {
  uid_t default_user_id;
  gid_t default_user_group;

  if (out_of_capacity) *out_of_capacity = false;

  // For testing.
  if (!forced_crash_directory_.empty()) {
    *crash_directory = forced_crash_directory_;
    return true;
  }

  if (!GetUserInfoFromName(kDefaultUserName,
                           &default_user_id,
                           &default_user_group)) {
    LOG(ERROR) << "Could not find default user info";
    return false;
  }
  mode_t directory_mode;
  uid_t directory_owner;
  gid_t directory_group;
  *crash_directory =
      GetCrashDirectoryInfo(euid,
                            default_user_id,
                            default_user_group,
                            &directory_mode,
                            &directory_owner,
                            &directory_group);

  if (!base::PathExists(*crash_directory)) {
    // Create the spool directory with the appropriate mode (regardless of
    // umask) and ownership.
    mode_t old_mask = umask(0);
    if (mkdir(crash_directory->value().c_str(), directory_mode) < 0 ||
        chown(crash_directory->value().c_str(),
              directory_owner,
              directory_group) < 0) {
      LOG(ERROR) << "Unable to create appropriate crash directory";
      return false;
    }
    umask(old_mask);
  }

  if (!base::PathExists(*crash_directory)) {
    LOG(ERROR) << "Unable to create crash directory "
               << crash_directory->value().c_str();
    return false;
  }

  if (!CheckHasCapacity(*crash_directory)) {
    if (out_of_capacity) *out_of_capacity = true;
    return false;
  }

  return true;
}

// static
FilePath CrashCollector::GetProcessPath(pid_t pid) {
  return FilePath(StringPrintf("/proc/%d", pid));
}

bool CrashCollector::GetSymlinkTarget(const FilePath &symlink,
                                      FilePath *target) {
  ssize_t max_size = 64;
  std::vector<char> buffer;

  while (true) {
    buffer.resize(max_size + 1);
    ssize_t size = readlink(symlink.value().c_str(), buffer.data(), max_size);
    if (size < 0) {
      int saved_errno = errno;
      LOG(ERROR) << "Readlink failed on " << symlink.value() << " with "
                 << saved_errno;
      return false;
    }

    buffer[size] = 0;
    if (size == max_size) {
      max_size *= 2;
      if (max_size > PATH_MAX) {
        return false;
      }
      continue;
    }
    break;
  }

  *target = FilePath(buffer.data());
  return true;
}

bool CrashCollector::GetExecutableBaseNameFromPid(pid_t pid,
                                                  std::string *base_name) {
  FilePath target;
  FilePath process_path = GetProcessPath(pid);
  FilePath exe_path = process_path.Append("exe");
  if (!GetSymlinkTarget(exe_path, &target)) {
    LOG(INFO) << "GetSymlinkTarget failed - Path " << process_path.value()
              << " DirectoryExists: "
              << base::DirectoryExists(process_path);
    // Try to further diagnose exe readlink failure cause.
    struct stat buf;
    int stat_result = stat(exe_path.value().c_str(), &buf);
    int saved_errno = errno;
    if (stat_result < 0) {
      LOG(INFO) << "stat " << exe_path.value() << " failed: " << stat_result
                << " " << saved_errno;
    } else {
      LOG(INFO) << "stat " << exe_path.value() << " succeeded: st_mode="
                << buf.st_mode;
    }
    return false;
  }
  *base_name = target.BaseName().value();
  return true;
}

// Return true if the given crash directory has not already reached
// maximum capacity.
bool CrashCollector::CheckHasCapacity(const FilePath &crash_directory) {
  DIR* dir = opendir(crash_directory.value().c_str());
  if (!dir) {
    return false;
  }
  struct dirent ent_buf;
  struct dirent* ent;
  bool full = false;
  std::set<std::string> basenames;
  while (readdir_r(dir, &ent_buf, &ent) == 0 && ent) {
    if ((strcmp(ent->d_name, ".") == 0) ||
        (strcmp(ent->d_name, "..") == 0))
      continue;

    std::string filename(ent->d_name);
    size_t last_dot = filename.rfind(".");
    std::string basename;
    // If there is a valid looking extension, use the base part of the
    // name.  If the only dot is the first byte (aka a dot file), treat
    // it as unique to avoid allowing a directory full of dot files
    // from accumulating.
    if (last_dot != std::string::npos && last_dot != 0)
      basename = filename.substr(0, last_dot);
    else
      basename = filename;
    basenames.insert(basename);

    if (basenames.size() >= static_cast<size_t>(kMaxCrashDirectorySize)) {
      LOG(WARNING) << "Crash directory " << crash_directory.value()
                   << " already full with " << kMaxCrashDirectorySize
                   << " pending reports";
      full = true;
      break;
    }
  }
  closedir(dir);
  return !full;
}

bool CrashCollector::GetLogContents(const FilePath &config_path,
                                    const std::string &exec_name,
                                    const FilePath &output_file) {
  brillo::KeyValueStore store;
  if (!store.Load(config_path)) {
    LOG(WARNING) << "Unable to read log configuration file "
                 << config_path.value();
    return false;
  }

  std::string command;
  if (!store.GetString(exec_name, &command))
    return false;

  FilePath raw_output_file;
  if (!base::CreateTemporaryFile(&raw_output_file)) {
    LOG(WARNING) << "Failed to create temporary file for raw log output.";
    return false;
  }

  brillo::ProcessImpl diag_process;
  diag_process.AddArg(kShellPath);
  diag_process.AddStringOption("-c", command);
  diag_process.RedirectOutput(raw_output_file.value());

  const int result = diag_process.Run();
  if (result != 0) {
    LOG(WARNING) << "Log command \"" << command << "\" exited with " << result;
    return false;
  }

  std::string log_contents;
  const bool fully_read = base::ReadFileToStringWithMaxSize(
      raw_output_file, &log_contents, max_log_size_);
  base::DeleteFile(raw_output_file, false);

  if (!fully_read) {
    if (log_contents.empty()) {
      LOG(WARNING) << "Failed to read raw log contents.";
      return false;
    }
    // If ReadFileToStringWithMaxSize returned false and log_contents is
    // non-empty, this means the log is larger than max_log_size_.
    LOG(WARNING) << "Log is larger than " << max_log_size_
                 << " bytes. Truncating.";
    log_contents.append("\n<TRUNCATED>\n");
  }

  StripSensitiveData(&log_contents);

  // 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(output_file,
                   log_contents.data(),
                   log_contents.size()) !=
      static_cast<int>(log_contents.length())) {
    LOG(WARNING) << "Error writing sanitized log to "
                 << output_file.value().c_str();
    return false;
  }

  return true;
}

void CrashCollector::AddCrashMetaData(const std::string &key,
                                      const std::string &value) {
  extra_metadata_.append(StringPrintf("%s=%s\n", key.c_str(), value.c_str()));
}

void CrashCollector::AddCrashMetaUploadFile(const std::string &key,
                                            const std::string &path) {
  if (!path.empty())
    AddCrashMetaData(kUploadFilePrefix + key, path);
}

void CrashCollector::AddCrashMetaUploadData(const std::string &key,
                                            const std::string &value) {
  if (!value.empty())
    AddCrashMetaData(kUploadVarPrefix + key, value);
}

void CrashCollector::AddCrashMetaUploadText(const std::string &key,
                                            const std::string &path) {
  if (!path.empty())
    AddCrashMetaData(kUploadTextPrefix + key, path);
}

std::string CrashCollector::GetVersion() const {
  brillo::KeyValueStore store;
  if (!store.Load(lsb_release_)) {
    LOG(WARNING) << "Problem parsing " << lsb_release_.value();
    // Even though there was some failure, take as much as we could read.
  }
  FilePath saved_lsb = system_crash_path_.Append(lsb_release_.BaseName());
  if (!store.Load(saved_lsb)) {
    if (base::PathExists(saved_lsb)) {
      LOG(WARNING) << "Unable to parse " << saved_lsb.value();
      // We already loaded the system file, so no need to error out here.
    }
  }

  std::string version = kUnknownVersion;
  if (!store.GetString(kLsbVersionKey, &version)) {
    LOG(WARNING) << "Unable to read " << kLsbVersionKey << " from "
                 << saved_lsb.value() << " or " << lsb_release_.value();
  }

  return version;
}

void CrashCollector::WriteCrashMetaData(const FilePath &meta_path,
                                        const std::string &exec_name,
                                        const std::string &payload_path) {
  int64_t payload_size = -1;
  base::GetFileSize(FilePath(payload_path), &payload_size);
  const std::string version = GetVersion();
  std::string meta_data = StringPrintf("%sexec_name=%s\n"
                                       "ver=%s\n"
                                       "payload=%s\n"
                                       "payload_size=%" PRId64 "\n"
                                       "done=1\n",
                                       extra_metadata_.c_str(),
                                       exec_name.c_str(),
                                       version.c_str(),
                                       payload_path.c_str(),
                                       payload_size);
  // 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(meta_path, meta_data.c_str(), meta_data.size()) < 0) {
    LOG(ERROR) << "Unable to write " << meta_path.value();
  }
}

bool CrashCollector::IsCrashTestInProgress() {
  return base::PathExists(FilePath(kCrashTestInProgressPath));
}

bool CrashCollector::IsDeveloperImage() {
  // If we're testing crash reporter itself, we don't want to special-case
  // for developer images.
  if (IsCrashTestInProgress())
    return false;
  return base::PathExists(FilePath(kLeaveCoreFile));
}

bool CrashCollector::ShouldHandleChromeCrashes() {
  // If we're testing crash reporter itself, we don't want to allow an
  // override for chrome crashes.  And, let's be conservative and only
  // allow an override for developer images.
  if (!IsCrashTestInProgress() && IsDeveloperImage()) {
    // Check if there's an override to indicate we should indeed collect
    // chrome crashes.  This allows the crashes to still be tracked when
    // they occur in autotests.  See "crosbug.com/17987".
    if (base::PathExists(FilePath(kCollectChromeFile)))
      return true;
  }
  // We default to ignoring chrome crashes.
  return false;
}

bool CrashCollector::IsUserSpecificDirectoryEnabled() {
  return !ShouldHandleChromeCrashes();
}

FilePath CrashCollector::GzipFile(const FilePath& path) {
  brillo::ProcessImpl proc;
  proc.AddArg(kGzipPath);
  proc.AddArg(path.value());
  const int res = proc.Run();
  if (res != 0) {
    LOG(ERROR) << "Failed to gzip " << path.value();
    return FilePath();
  }
  return path.AddExtension(".gz");
}

// Hash a string to a number.  We define our own hash function to not
// be dependent on a C++ library that might change.  This function
// uses basically the same approach as tr1/functional_hash.h but with
// a larger prime number (16127 vs 131).
unsigned CrashCollector::HashString(base::StringPiece input) {
  unsigned hash = 0;
  for (auto c : input)
    hash = hash * 16127 + c;
  return hash;
}