crash_reporter/crash_collector.cc

// 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 <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.
#define __STDC_FORMAT_MACROS // PRId64
#include <inttypes.h>

#include <set>
#include <vector>

#include "base/eintr_wrapper.h"
#include "base/file_util.h"
#include "base/logging.h"
#include "base/string_split.h"
#include "base/string_util.h"
#include "chromeos/process.h"

static const char kCollectChromeFile[] =
    "/mnt/stateful_partition/etc/collect_chrome_crashes";
static const char kCollectUdevSignature[] = "crash_reporter-udev-collection";
static const char kCrashTestInProgressPath[] = "/tmp/crash-test-in-progress";
static const char kDefaultLogConfig[] = "/etc/crash_reporter_logs.conf";
static const char kDefaultUserName[] = "chronos";
static const char kLeaveCoreFile[] = "/root/.leave_core";
static const char kLsbRelease[] = "/etc/lsb-release";
static const char kShellPath[] = "/bin/sh";
static const char kSystemCrashPath[] = "/var/spool/crash";
static const char kUdevExecName[] = "udev";
static const char kUdevSignatureKey[] = "sig";
static const char kUserCrashPath[] = "/home/chronos/user/crash";

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

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

static const uid_t kRootOwner = 0;
static const uid_t kRootGroup = 0;

// 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;

CrashCollector::CrashCollector()
    : forced_crash_directory_(NULL),
      lsb_release_(kLsbRelease) {
}

CrashCollector::~CrashCollector() {
}

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

  count_crash_function_ = count_crash_function;
  is_feedback_allowed_function_ = is_feedback_allowed_function;
}

bool CrashCollector::HandleUdevCrash(const std::string &udev_event) {
  // Process the udev event string.
  // The udev string should be formatted as follows:
  //   "ACTION=[action]:KERNEL=[name]:SUBSYSTEM=[subsystem]"
  // The values don't have to be in any particular order.

  // First get all the key-value pairs.
  std::vector<std::pair<std::string, std::string> > udev_event_keyval;
  base::SplitStringIntoKeyValuePairs(udev_event, '=', ':', &udev_event_keyval);
  std::vector<std::pair<std::string, std::string> >::const_iterator iter;
  std::map<std::string, std::string> udev_event_map;
  for (iter = udev_event_keyval.begin();
       iter != udev_event_keyval.end();
       ++iter) {
    udev_event_map[iter->first] = iter->second;
  }

  // Construct the basename string for crash_reporter_logs.conf:
  //   "crash_reporter-udev-collection-[action]-[name]-[subsystem]"
  // If a udev field is not provided, "" is used in its place, e.g.:
  //   "crash_reporter-udev-collection-[action]--[subsystem]"
  // Hence, "" is used as a wildcard name string.
  std::string basename = udev_event_map["ACTION"] + "-" +
                         udev_event_map["KERNEL"] + "-" +
                         udev_event_map["SUBSYSTEM"];
  std::string udev_log_name = std::string(kCollectUdevSignature) + '-' +
                              basename;

  // Make sure the crash directory exists, or create it if it doesn't.
  FilePath crash_directory;
  if (!GetCreatedCrashDirectoryByEuid(0, &crash_directory, NULL)) {
    LOG(ERROR) << "Could not get crash directory.";
    return false;
  }
  // Create the destination path.
  std::string log_file_name =
      FormatDumpBasename(basename, time(NULL), 0);
  FilePath crash_path = GetCrashPath(crash_directory, log_file_name, "log");

  // Handle the crash.
  bool result = GetLogContents(FilePath(kDefaultLogConfig), udev_log_name,
                               crash_path);
  if (!result) {
    LOG(ERROR) << "Error reading udev log info " << udev_log_name;
    return false;
  }

  AddCrashMetaData(kUdevSignatureKey, kCollectUdevSignature);
  WriteCrashMetaData(GetCrashPath(crash_directory, log_file_name, "meta"),
                     kUdevExecName, crash_path.value());
  return true;
}

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 = file_util::WriteFileDescriptor(fd, data, size);
  HANDLE_EINTR(close(fd));
  return rv;
}

std::string CrashCollector::Sanitize(const std::string &name) {
  std::string result = name;
  for (size_t i = 0; i < name.size(); ++i) {
    if (!isalnum(result[i]) && result[i] != '_')
      result[i] = '_';
  }
  return result;
}

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()));
}

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()) {
    *mode = kUserCrashPathMode;
    *directory_owner = default_user_id;
    *directory_group = default_user_group;
    return FilePath(kUserCrashPath);
  } else {
    *mode = kSystemCrashPathMode;
    *directory_owner = kRootOwner;
    *directory_group = kRootGroup;
    return FilePath(kSystemCrashPath);
  }
}

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

  if (getpwnam_r(name.c_str(), &passwd_storage, storage, sizeof(storage),
                 &passwd_result) != 0 || passwd_result == NULL) {
    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 != NULL) *out_of_capacity = false;

  // For testing.
  if (forced_crash_directory_ != NULL) {
    *crash_directory = FilePath(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 (!file_util::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 (!file_util::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 != NULL) *out_of_capacity = true;
    return false;
  }

  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 != NULL) {
    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::IsCommentLine(const std::string &line) {
  size_t found = line.find_first_not_of(" ");
  return found != std::string::npos && line[found] == '#';
}

bool CrashCollector::ReadKeyValueFile(
    const FilePath &path,
    const char separator,
    std::map<std::string, std::string> *dictionary) {
  std::string contents;
  if (!file_util::ReadFileToString(path, &contents)) {
    return false;
  }
  typedef std::vector<std::string> StringVector;
  StringVector lines;
  base::SplitString(contents, '\n', &lines);
  bool any_errors = false;
  for (StringVector::iterator line = lines.begin(); line != lines.end();
       ++line) {
    // Allow empty strings.
    if (line->empty())
      continue;
    // Allow comment lines.
    if (IsCommentLine(*line))
      continue;
    StringVector sides;
    base::SplitString(*line, separator, &sides);
    if (sides.size() != 2) {
      any_errors = true;
      continue;
    }
    dictionary->insert(std::pair<std::string, std::string>(sides[0], sides[1]));
  }
  return !any_errors;
}

bool CrashCollector::GetLogContents(const FilePath &config_path,
                                    const std::string &exec_name,
                                    const FilePath &output_file) {
  std::map<std::string, std::string> log_commands;
  if (!ReadKeyValueFile(config_path, ':', &log_commands)) {
    LOG(INFO) << "Unable to read log configuration file "
              << config_path.value();
    return false;
  }

  if (log_commands.find(exec_name) == log_commands.end())
    return false;

  chromeos::ProcessImpl diag_process;
  diag_process.AddArg(kShellPath);
  std::string shell_command = log_commands[exec_name];
  diag_process.AddStringOption("-c", shell_command);
  diag_process.RedirectOutput(output_file.value());

  int result = diag_process.Run();
  if (result != 0) {
    LOG(INFO) << "Running shell command " << shell_command << "failed with: "
              << result;
    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::WriteCrashMetaData(const FilePath &meta_path,
                                        const std::string &exec_name,
                                        const std::string &payload_path) {
  std::map<std::string, std::string> contents;
  if (!ReadKeyValueFile(FilePath(std::string(lsb_release_)), '=', &contents)) {
    LOG(ERROR) << "Problem parsing " << lsb_release_;
    // Even though there was some failure, take as much as we could read.
  }
  std::string version("unknown");
  std::map<std::string, std::string>::iterator i;
  if ((i = contents.find("CHROMEOS_RELEASE_VERSION")) != contents.end()) {
    version = i->second;
  }
  int64 payload_size = -1;
  file_util::GetFileSize(FilePath(payload_path), &payload_size);
  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 file_util::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 file_util::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 file_util::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 (file_util::PathExists(FilePath(kCollectChromeFile)))
      return true;
  }
  // We default to ignoring chrome crashes.
  return false;
}

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