// Copyright (c) 2012 The Chromium 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 "content/browser/child_process_security_policy_impl.h"

#include <utility>

#include "base/command_line.h"
#include "base/files/file_path.h"
#include "base/logging.h"
#include "base/macros.h"
#include "base/metrics/histogram.h"
#include "base/stl_util.h"
#include "base/strings/string_util.h"
#include "build/build_config.h"
#include "content/browser/site_instance_impl.h"
#include "content/common/site_isolation_policy.h"
#include "content/public/browser/child_process_data.h"
#include "content/public/browser/content_browser_client.h"
#include "content/public/browser/render_process_host.h"
#include "content/public/common/bindings_policy.h"
#include "content/public/common/url_constants.h"
#include "net/base/filename_util.h"
#include "net/url_request/url_request.h"
#include "storage/browser/fileapi/file_permission_policy.h"
#include "storage/browser/fileapi/file_system_url.h"
#include "storage/browser/fileapi/isolated_context.h"
#include "storage/common/fileapi/file_system_util.h"
#include "url/gurl.h"

namespace content {

namespace {

// Used internally only. These bit positions have no relationship to any
// underlying OS and can be changed to accommodate finer-grained permissions.
enum ChildProcessSecurityPermissions {
  READ_FILE_PERMISSION             = 1 << 0,
  WRITE_FILE_PERMISSION            = 1 << 1,
  CREATE_NEW_FILE_PERMISSION       = 1 << 2,
  CREATE_OVERWRITE_FILE_PERMISSION = 1 << 3,
  DELETE_FILE_PERMISSION           = 1 << 4,

  // Used by Media Galleries API
  COPY_INTO_FILE_PERMISSION        = 1 << 5,
};

// Used internally only. Bitmasks that are actually used by the Grant* and Can*
// methods. These contain one or more ChildProcessSecurityPermissions.
enum ChildProcessSecurityGrants {
  READ_FILE_GRANT              = READ_FILE_PERMISSION,
  WRITE_FILE_GRANT             = WRITE_FILE_PERMISSION,

  CREATE_NEW_FILE_GRANT        = CREATE_NEW_FILE_PERMISSION |
                                 COPY_INTO_FILE_PERMISSION,

  CREATE_READ_WRITE_FILE_GRANT = CREATE_NEW_FILE_PERMISSION |
                                 CREATE_OVERWRITE_FILE_PERMISSION |
                                 READ_FILE_PERMISSION |
                                 WRITE_FILE_PERMISSION |
                                 COPY_INTO_FILE_PERMISSION |
                                 DELETE_FILE_PERMISSION,

  COPY_INTO_FILE_GRANT         = COPY_INTO_FILE_PERMISSION,
  DELETE_FILE_GRANT            = DELETE_FILE_PERMISSION,
};

}  // namespace

// The SecurityState class is used to maintain per-child process security state
// information.
class ChildProcessSecurityPolicyImpl::SecurityState {
 public:
  SecurityState()
    : enabled_bindings_(0),
      can_read_raw_cookies_(false),
      can_send_midi_sysex_(false) { }

  ~SecurityState() {
    scheme_policy_.clear();
    storage::IsolatedContext* isolated_context =
        storage::IsolatedContext::GetInstance();
    for (FileSystemMap::iterator iter = filesystem_permissions_.begin();
         iter != filesystem_permissions_.end();
         ++iter) {
      isolated_context->RemoveReference(iter->first);
    }
    UMA_HISTOGRAM_COUNTS("ChildProcessSecurityPolicy.PerChildFilePermissions",
                         file_permissions_.size());
  }

  // Grant permission to request URLs with the specified origin.
  void GrantOrigin(const url::Origin& origin) {
    origin_set_.insert(origin);
  }

  // Grant permission to request URLs with the specified scheme.
  void GrantScheme(const std::string& scheme) {
    scheme_policy_[scheme] = true;
  }

  // Revoke permission to request URLs with the specified scheme.
  void RevokeScheme(const std::string& scheme) {
    scheme_policy_[scheme] = false;
  }

  // Grant certain permissions to a file.
  void GrantPermissionsForFile(const base::FilePath& file, int permissions) {
    base::FilePath stripped = file.StripTrailingSeparators();
    file_permissions_[stripped] |= permissions;
    UMA_HISTOGRAM_COUNTS("ChildProcessSecurityPolicy.FilePermissionPathLength",
                         stripped.value().size());
  }

  // Grant navigation to a file but not the file:// scheme in general.
  void GrantRequestOfSpecificFile(const base::FilePath &file) {
    request_file_set_.insert(file.StripTrailingSeparators());
  }

  // Revokes all permissions granted to a file.
  void RevokeAllPermissionsForFile(const base::FilePath& file) {
    base::FilePath stripped = file.StripTrailingSeparators();
    file_permissions_.erase(stripped);
    request_file_set_.erase(stripped);
  }

  // Grant certain permissions to a file.
  void GrantPermissionsForFileSystem(const std::string& filesystem_id,
                                     int permissions) {
    if (!ContainsKey(filesystem_permissions_, filesystem_id))
      storage::IsolatedContext::GetInstance()->AddReference(filesystem_id);
    filesystem_permissions_[filesystem_id] |= permissions;
  }

  bool HasPermissionsForFileSystem(const std::string& filesystem_id,
                                   int permissions) {
    FileSystemMap::const_iterator it =
        filesystem_permissions_.find(filesystem_id);
    if (it == filesystem_permissions_.end())
      return false;
    return (it->second & permissions) == permissions;
  }

#if defined(OS_ANDROID)
  // Determine if the certain permissions have been granted to a content URI.
  bool HasPermissionsForContentUri(const base::FilePath& file,
                                   int permissions) {
    DCHECK(!file.empty());
    DCHECK(file.IsContentUri());
    if (!permissions)
      return false;
    base::FilePath file_path = file.StripTrailingSeparators();
    FileMap::const_iterator it = file_permissions_.find(file_path);
    if (it != file_permissions_.end())
      return (it->second & permissions) == permissions;
    return false;
  }
#endif

  void GrantBindings(int bindings) {
    enabled_bindings_ |= bindings;
  }

  void GrantReadRawCookies() {
    can_read_raw_cookies_ = true;
  }

  void RevokeReadRawCookies() {
    can_read_raw_cookies_ = false;
  }

  void GrantPermissionForMidiSysEx() {
    can_send_midi_sysex_ = true;
  }

  // Determine whether permission has been granted to commit |url|.
  bool CanCommitURL(const GURL& url) {
    // Having permission to a scheme implies permission to all of its URLs.
    SchemeMap::const_iterator scheme_judgment(
        scheme_policy_.find(url.scheme()));
    if (scheme_judgment != scheme_policy_.end())
      return scheme_judgment->second;

    // Otherwise, check for permission for specific origin.
    if (ContainsKey(origin_set_, url::Origin(url)))
      return true;

    // file:// URLs are more granular.  The child may have been given
    // permission to a specific file but not the file:// scheme in general.
    if (url.SchemeIs(url::kFileScheme)) {
      base::FilePath path;
      if (net::FileURLToFilePath(url, &path))
        return ContainsKey(request_file_set_, path);
    }

    return false;  // Unmentioned schemes are disallowed.
  }

  // Determine if the certain permissions have been granted to a file.
  bool HasPermissionsForFile(const base::FilePath& file, int permissions) {
#if defined(OS_ANDROID)
    if (file.IsContentUri())
      return HasPermissionsForContentUri(file, permissions);
#endif
    if (!permissions || file.empty() || !file.IsAbsolute())
      return false;
    base::FilePath current_path = file.StripTrailingSeparators();
    base::FilePath last_path;
    int skip = 0;
    while (current_path != last_path) {
      base::FilePath base_name = current_path.BaseName();
      if (base_name.value() == base::FilePath::kParentDirectory) {
        ++skip;
      } else if (skip > 0) {
        if (base_name.value() != base::FilePath::kCurrentDirectory)
          --skip;
      } else {
        FileMap::const_iterator it = file_permissions_.find(current_path);
        if (it != file_permissions_.end())
          return (it->second & permissions) == permissions;
      }
      last_path = current_path;
      current_path = current_path.DirName();
    }

    return false;
  }

  bool CanAccessDataForOrigin(const GURL& gurl) {
    if (origin_lock_.is_empty())
      return true;
    // TODO(creis): We must pass the valid browser_context to convert hosted
    // apps URLs.  Currently, hosted apps cannot set cookies in this mode.
    // See http://crbug.com/160576.
    GURL site_gurl = SiteInstanceImpl::GetSiteForURL(NULL, gurl);
    return origin_lock_ == site_gurl;
  }

  void LockToOrigin(const GURL& gurl) {
    origin_lock_ = gurl;
  }

  bool has_web_ui_bindings() const {
    return enabled_bindings_ & BINDINGS_POLICY_WEB_UI;
  }

  bool can_read_raw_cookies() const {
    return can_read_raw_cookies_;
  }

  bool can_send_midi_sysex() const {
    return can_send_midi_sysex_;
  }

 private:
  typedef std::map<std::string, bool> SchemeMap;
  typedef std::set<url::Origin> OriginSet;

  typedef int FilePermissionFlags;  // bit-set of base::File::Flags
  typedef std::map<base::FilePath, FilePermissionFlags> FileMap;
  typedef std::map<std::string, FilePermissionFlags> FileSystemMap;
  typedef std::set<base::FilePath> FileSet;

  // Maps URL schemes to whether permission has been granted or revoked:
  //   |true| means the scheme has been granted.
  //   |false| means the scheme has been revoked.
  // If a scheme is not present in the map, then it has never been granted
  // or revoked.
  SchemeMap scheme_policy_;

  // The set of URL origins to which the child process has been granted
  // permission.
  OriginSet origin_set_;

  // The set of files the child process is permited to upload to the web.
  FileMap file_permissions_;

  // The set of files the child process is permitted to load.
  FileSet request_file_set_;

  int enabled_bindings_;

  bool can_read_raw_cookies_;

  bool can_send_midi_sysex_;

  GURL origin_lock_;

  // The set of isolated filesystems the child process is permitted to access.
  FileSystemMap filesystem_permissions_;

  DISALLOW_COPY_AND_ASSIGN(SecurityState);
};

ChildProcessSecurityPolicyImpl::ChildProcessSecurityPolicyImpl() {
  // We know about these schemes and believe them to be safe.
  RegisterWebSafeScheme(url::kHttpScheme);
  RegisterWebSafeScheme(url::kHttpsScheme);
  RegisterWebSafeScheme(url::kFtpScheme);
  RegisterWebSafeScheme(url::kDataScheme);
  RegisterWebSafeScheme("feed");
  RegisterWebSafeScheme(url::kBlobScheme);
  RegisterWebSafeScheme(url::kFileSystemScheme);

  // We know about the following pseudo schemes and treat them specially.
  RegisterPseudoScheme(url::kAboutScheme);
  RegisterPseudoScheme(url::kJavaScriptScheme);
  RegisterPseudoScheme(kViewSourceScheme);
}

ChildProcessSecurityPolicyImpl::~ChildProcessSecurityPolicyImpl() {
  web_safe_schemes_.clear();
  pseudo_schemes_.clear();
  STLDeleteContainerPairSecondPointers(security_state_.begin(),
                                       security_state_.end());
  security_state_.clear();
}

// static
ChildProcessSecurityPolicy* ChildProcessSecurityPolicy::GetInstance() {
  return ChildProcessSecurityPolicyImpl::GetInstance();
}

ChildProcessSecurityPolicyImpl* ChildProcessSecurityPolicyImpl::GetInstance() {
  return base::Singleton<ChildProcessSecurityPolicyImpl>::get();
}

void ChildProcessSecurityPolicyImpl::Add(int child_id) {
  base::AutoLock lock(lock_);
  AddChild(child_id);
}

void ChildProcessSecurityPolicyImpl::AddWorker(int child_id,
                                               int main_render_process_id) {
  base::AutoLock lock(lock_);
  AddChild(child_id);
  worker_map_[child_id] = main_render_process_id;
}

void ChildProcessSecurityPolicyImpl::Remove(int child_id) {
  base::AutoLock lock(lock_);
  SecurityStateMap::iterator it = security_state_.find(child_id);
  if (it == security_state_.end())
    return;  // May be called multiple times.

  delete it->second;
  security_state_.erase(it);
  worker_map_.erase(child_id);
}

void ChildProcessSecurityPolicyImpl::RegisterWebSafeScheme(
    const std::string& scheme) {
  base::AutoLock lock(lock_);
  DCHECK_EQ(0U, web_safe_schemes_.count(scheme)) << "Add schemes at most once.";
  DCHECK_EQ(0U, pseudo_schemes_.count(scheme))
      << "Web-safe implies not pseudo.";

  web_safe_schemes_.insert(scheme);
}

bool ChildProcessSecurityPolicyImpl::IsWebSafeScheme(
    const std::string& scheme) {
  base::AutoLock lock(lock_);

  return ContainsKey(web_safe_schemes_, scheme);
}

void ChildProcessSecurityPolicyImpl::RegisterPseudoScheme(
    const std::string& scheme) {
  base::AutoLock lock(lock_);
  DCHECK_EQ(0U, pseudo_schemes_.count(scheme)) << "Add schemes at most once.";
  DCHECK_EQ(0U, web_safe_schemes_.count(scheme))
      << "Pseudo implies not web-safe.";

  pseudo_schemes_.insert(scheme);
}

bool ChildProcessSecurityPolicyImpl::IsPseudoScheme(
    const std::string& scheme) {
  base::AutoLock lock(lock_);

  return ContainsKey(pseudo_schemes_, scheme);
}

void ChildProcessSecurityPolicyImpl::GrantRequestURL(
    int child_id, const GURL& url) {

  if (!url.is_valid())
    return;  // Can't grant the capability to request invalid URLs.

  if (IsWebSafeScheme(url.scheme()))
    return;  // The scheme has already been whitelisted for every child process.

  if (IsPseudoScheme(url.scheme())) {
    // The view-source scheme is a special case of a pseudo-URL that eventually
    // results in requesting its embedded URL.
    if (url.SchemeIs(kViewSourceScheme)) {
      // URLs with the view-source scheme typically look like:
      //   view-source:http://www.google.com/a
      // In order to request these URLs, the child_id needs to be able to
      // request the embedded URL.
      GrantRequestURL(child_id, GURL(url.GetContent()));
    }

    return;  // Can't grant the capability to request pseudo schemes.
  }

  {
    base::AutoLock lock(lock_);
    SecurityStateMap::iterator state = security_state_.find(child_id);
    if (state == security_state_.end())
      return;

    // When the child process has been commanded to request this scheme,
    // we grant it the capability to request all URLs of that scheme.
    state->second->GrantScheme(url.scheme());
  }
}

void ChildProcessSecurityPolicyImpl::GrantRequestSpecificFileURL(
    int child_id,
    const GURL& url) {
  if (!url.SchemeIs(url::kFileScheme))
    return;

  {
    base::AutoLock lock(lock_);
    SecurityStateMap::iterator state = security_state_.find(child_id);
    if (state == security_state_.end())
      return;

    // When the child process has been commanded to request a file:// URL,
    // then we grant it the capability for that URL only.
    base::FilePath path;
    if (net::FileURLToFilePath(url, &path))
      state->second->GrantRequestOfSpecificFile(path);
  }
}

void ChildProcessSecurityPolicyImpl::GrantReadFile(int child_id,
                                                   const base::FilePath& file) {
  GrantPermissionsForFile(child_id, file, READ_FILE_GRANT);
}

void ChildProcessSecurityPolicyImpl::GrantCreateReadWriteFile(
    int child_id, const base::FilePath& file) {
  GrantPermissionsForFile(child_id, file, CREATE_READ_WRITE_FILE_GRANT);
}

void ChildProcessSecurityPolicyImpl::GrantCopyInto(int child_id,
                                                   const base::FilePath& dir) {
  GrantPermissionsForFile(child_id, dir, COPY_INTO_FILE_GRANT);
}

void ChildProcessSecurityPolicyImpl::GrantDeleteFrom(
    int child_id, const base::FilePath& dir) {
  GrantPermissionsForFile(child_id, dir, DELETE_FILE_GRANT);
}

void ChildProcessSecurityPolicyImpl::GrantPermissionsForFile(
    int child_id, const base::FilePath& file, int permissions) {
  base::AutoLock lock(lock_);

  SecurityStateMap::iterator state = security_state_.find(child_id);
  if (state == security_state_.end())
    return;

  state->second->GrantPermissionsForFile(file, permissions);
}

void ChildProcessSecurityPolicyImpl::RevokeAllPermissionsForFile(
    int child_id, const base::FilePath& file) {
  base::AutoLock lock(lock_);

  SecurityStateMap::iterator state = security_state_.find(child_id);
  if (state == security_state_.end())
    return;

  state->second->RevokeAllPermissionsForFile(file);
}

void ChildProcessSecurityPolicyImpl::GrantReadFileSystem(
    int child_id, const std::string& filesystem_id) {
  GrantPermissionsForFileSystem(child_id, filesystem_id, READ_FILE_GRANT);
}

void ChildProcessSecurityPolicyImpl::GrantWriteFileSystem(
    int child_id, const std::string& filesystem_id) {
  GrantPermissionsForFileSystem(child_id, filesystem_id, WRITE_FILE_GRANT);
}

void ChildProcessSecurityPolicyImpl::GrantCreateFileForFileSystem(
    int child_id, const std::string& filesystem_id) {
  GrantPermissionsForFileSystem(child_id, filesystem_id, CREATE_NEW_FILE_GRANT);
}

void ChildProcessSecurityPolicyImpl::GrantCreateReadWriteFileSystem(
    int child_id, const std::string& filesystem_id) {
  GrantPermissionsForFileSystem(
      child_id, filesystem_id, CREATE_READ_WRITE_FILE_GRANT);
}

void ChildProcessSecurityPolicyImpl::GrantCopyIntoFileSystem(
    int child_id, const std::string& filesystem_id) {
  GrantPermissionsForFileSystem(child_id, filesystem_id, COPY_INTO_FILE_GRANT);
}

void ChildProcessSecurityPolicyImpl::GrantDeleteFromFileSystem(
    int child_id, const std::string& filesystem_id) {
  GrantPermissionsForFileSystem(child_id, filesystem_id, DELETE_FILE_GRANT);
}

void ChildProcessSecurityPolicyImpl::GrantSendMidiSysExMessage(int child_id) {
  base::AutoLock lock(lock_);

  SecurityStateMap::iterator state = security_state_.find(child_id);
  if (state == security_state_.end())
    return;

  state->second->GrantPermissionForMidiSysEx();
}

void ChildProcessSecurityPolicyImpl::GrantOrigin(int child_id,
                                                 const url::Origin& origin) {
  base::AutoLock lock(lock_);

  SecurityStateMap::iterator state = security_state_.find(child_id);
  if (state == security_state_.end())
    return;

  state->second->GrantOrigin(origin);
}

void ChildProcessSecurityPolicyImpl::GrantScheme(int child_id,
                                                 const std::string& scheme) {
  base::AutoLock lock(lock_);

  SecurityStateMap::iterator state = security_state_.find(child_id);
  if (state == security_state_.end())
    return;

  state->second->GrantScheme(scheme);
}

void ChildProcessSecurityPolicyImpl::GrantWebUIBindings(int child_id) {
  base::AutoLock lock(lock_);

  SecurityStateMap::iterator state = security_state_.find(child_id);
  if (state == security_state_.end())
    return;

  state->second->GrantBindings(BINDINGS_POLICY_WEB_UI);

  // Web UI bindings need the ability to request chrome: URLs.
  state->second->GrantScheme(kChromeUIScheme);

  // Web UI pages can contain links to file:// URLs.
  state->second->GrantScheme(url::kFileScheme);
}

void ChildProcessSecurityPolicyImpl::GrantReadRawCookies(int child_id) {
  base::AutoLock lock(lock_);

  SecurityStateMap::iterator state = security_state_.find(child_id);
  if (state == security_state_.end())
    return;

  state->second->GrantReadRawCookies();
}

void ChildProcessSecurityPolicyImpl::RevokeReadRawCookies(int child_id) {
  base::AutoLock lock(lock_);

  SecurityStateMap::iterator state = security_state_.find(child_id);
  if (state == security_state_.end())
    return;

  state->second->RevokeReadRawCookies();
}

bool ChildProcessSecurityPolicyImpl::CanRequestURL(
    int child_id, const GURL& url) {
  if (!url.is_valid())
    return false;  // Can't request invalid URLs.

  if (IsPseudoScheme(url.scheme())) {
    // There are a number of special cases for pseudo schemes.

    if (url.SchemeIs(kViewSourceScheme)) {
      // A view-source URL is allowed if the child process is permitted to
      // request the embedded URL. Careful to avoid pointless recursion.
      GURL child_url(url.GetContent());
      if (child_url.SchemeIs(kViewSourceScheme) &&
          url.SchemeIs(kViewSourceScheme))
          return false;

      return CanRequestURL(child_id, child_url);
    }

    if (base::LowerCaseEqualsASCII(url.spec(), url::kAboutBlankURL))
      return true;  // Every child process can request <about:blank>.

    // URLs like <about:version> and <about:crash> shouldn't be requestable by
    // any child process.  Also, this case covers <javascript:...>, which should
    // be handled internally by the process and not kicked up to the browser.
    return false;
  }

  // If the process can commit the URL, it can request it.
  if (CanCommitURL(child_id, url))
    return true;

  // Also allow URLs destined for ShellExecute and not the browser itself.
  return !GetContentClient()->browser()->IsHandledURL(url) &&
         !net::URLRequest::IsHandledURL(url);
}

bool ChildProcessSecurityPolicyImpl::CanCommitURL(int child_id,
                                                  const GURL& url) {
  if (!url.is_valid())
    return false;  // Can't commit invalid URLs.

  // Of all the pseudo schemes, only about:blank is allowed to commit.
  if (IsPseudoScheme(url.scheme()))
    return base::LowerCaseEqualsASCII(url.spec(), url::kAboutBlankURL);

  // TODO(creis): Tighten this for Site Isolation, so that a URL from a site
  // that is isolated can only be committed in a process dedicated to that site.
  // CanRequestURL should still allow all web-safe schemes. See
  // https://crbug.com/515309.
  if (IsWebSafeScheme(url.scheme()))
    return true;  // The scheme has been white-listed for every child process.

  {
    base::AutoLock lock(lock_);

    SecurityStateMap::iterator state = security_state_.find(child_id);
    if (state == security_state_.end())
      return false;

    // Otherwise, we consult the child process's security state to see if it is
    // allowed to commit the URL.
    return state->second->CanCommitURL(url);
  }
}

bool ChildProcessSecurityPolicyImpl::CanReadFile(int child_id,
                                                 const base::FilePath& file) {
  return HasPermissionsForFile(child_id, file, READ_FILE_GRANT);
}

bool ChildProcessSecurityPolicyImpl::CanCreateReadWriteFile(
    int child_id,
    const base::FilePath& file) {
  return HasPermissionsForFile(child_id, file, CREATE_READ_WRITE_FILE_GRANT);
}

bool ChildProcessSecurityPolicyImpl::CanReadFileSystem(
    int child_id, const std::string& filesystem_id) {
  return HasPermissionsForFileSystem(child_id, filesystem_id, READ_FILE_GRANT);
}

bool ChildProcessSecurityPolicyImpl::CanReadWriteFileSystem(
    int child_id, const std::string& filesystem_id) {
  return HasPermissionsForFileSystem(child_id, filesystem_id,
                                     READ_FILE_GRANT | WRITE_FILE_GRANT);
}

bool ChildProcessSecurityPolicyImpl::CanCopyIntoFileSystem(
    int child_id, const std::string& filesystem_id) {
  return HasPermissionsForFileSystem(child_id, filesystem_id,
                                     COPY_INTO_FILE_GRANT);
}

bool ChildProcessSecurityPolicyImpl::CanDeleteFromFileSystem(
    int child_id, const std::string& filesystem_id) {
  return HasPermissionsForFileSystem(child_id, filesystem_id,
                                     DELETE_FILE_GRANT);
}

bool ChildProcessSecurityPolicyImpl::HasPermissionsForFile(
    int child_id, const base::FilePath& file, int permissions) {
  base::AutoLock lock(lock_);
  bool result = ChildProcessHasPermissionsForFile(child_id, file, permissions);
  if (!result) {
    // If this is a worker thread that has no access to a given file,
    // let's check that its renderer process has access to that file instead.
    WorkerToMainProcessMap::iterator iter = worker_map_.find(child_id);
    if (iter != worker_map_.end() && iter->second != 0) {
      result = ChildProcessHasPermissionsForFile(iter->second,
                                                 file,
                                                 permissions);
    }
  }
  return result;
}

bool ChildProcessSecurityPolicyImpl::HasPermissionsForFileSystemFile(
    int child_id,
    const storage::FileSystemURL& url,
    int permissions) {
  if (!url.is_valid())
    return false;

  if (url.path().ReferencesParent())
    return false;

  // Any write access is disallowed on the root path.
  if (storage::VirtualPath::IsRootPath(url.path()) &&
      (permissions & ~READ_FILE_GRANT)) {
    return false;
  }

  if (url.mount_type() == storage::kFileSystemTypeIsolated) {
    // When Isolated filesystems is overlayed on top of another filesystem,
    // its per-filesystem permission overrides the underlying filesystem
    // permissions).
    return HasPermissionsForFileSystem(
        child_id, url.mount_filesystem_id(), permissions);
  }

  FileSystemPermissionPolicyMap::iterator found =
      file_system_policy_map_.find(url.type());
  if (found == file_system_policy_map_.end())
    return false;

  if ((found->second & storage::FILE_PERMISSION_READ_ONLY) &&
      permissions & ~READ_FILE_GRANT) {
    return false;
  }

  if (found->second & storage::FILE_PERMISSION_USE_FILE_PERMISSION)
    return HasPermissionsForFile(child_id, url.path(), permissions);

  if (found->second & storage::FILE_PERMISSION_SANDBOX)
    return true;

  return false;
}

bool ChildProcessSecurityPolicyImpl::CanReadFileSystemFile(
    int child_id,
    const storage::FileSystemURL& url) {
  return HasPermissionsForFileSystemFile(child_id, url, READ_FILE_GRANT);
}

bool ChildProcessSecurityPolicyImpl::CanWriteFileSystemFile(
    int child_id,
    const storage::FileSystemURL& url) {
  return HasPermissionsForFileSystemFile(child_id, url, WRITE_FILE_GRANT);
}

bool ChildProcessSecurityPolicyImpl::CanCreateFileSystemFile(
    int child_id,
    const storage::FileSystemURL& url) {
  return HasPermissionsForFileSystemFile(child_id, url, CREATE_NEW_FILE_GRANT);
}

bool ChildProcessSecurityPolicyImpl::CanCreateReadWriteFileSystemFile(
    int child_id,
    const storage::FileSystemURL& url) {
  return HasPermissionsForFileSystemFile(child_id, url,
                                         CREATE_READ_WRITE_FILE_GRANT);
}

bool ChildProcessSecurityPolicyImpl::CanCopyIntoFileSystemFile(
    int child_id,
    const storage::FileSystemURL& url) {
  return HasPermissionsForFileSystemFile(child_id, url, COPY_INTO_FILE_GRANT);
}

bool ChildProcessSecurityPolicyImpl::CanDeleteFileSystemFile(
    int child_id,
    const storage::FileSystemURL& url) {
  return HasPermissionsForFileSystemFile(child_id, url, DELETE_FILE_GRANT);
}

bool ChildProcessSecurityPolicyImpl::HasWebUIBindings(int child_id) {
  base::AutoLock lock(lock_);

  SecurityStateMap::iterator state = security_state_.find(child_id);
  if (state == security_state_.end())
    return false;

  return state->second->has_web_ui_bindings();
}

bool ChildProcessSecurityPolicyImpl::CanReadRawCookies(int child_id) {
  base::AutoLock lock(lock_);

  SecurityStateMap::iterator state = security_state_.find(child_id);
  if (state == security_state_.end())
    return false;

  return state->second->can_read_raw_cookies();
}

void ChildProcessSecurityPolicyImpl::AddChild(int child_id) {
  if (security_state_.count(child_id) != 0) {
    NOTREACHED() << "Add child process at most once.";
    return;
  }

  security_state_[child_id] = new SecurityState();
}

bool ChildProcessSecurityPolicyImpl::ChildProcessHasPermissionsForFile(
    int child_id, const base::FilePath& file, int permissions) {
  SecurityStateMap::iterator state = security_state_.find(child_id);
  if (state == security_state_.end())
    return false;
  return state->second->HasPermissionsForFile(file, permissions);
}

bool ChildProcessSecurityPolicyImpl::CanAccessDataForOrigin(int child_id,
                                                            const GURL& gurl) {
  base::AutoLock lock(lock_);
  SecurityStateMap::iterator state = security_state_.find(child_id);
  if (state == security_state_.end()) {
    // TODO(nick): Returning true instead of false here is a temporary
    // workaround for https://crbug.com/600441
    return true;
  }
  return state->second->CanAccessDataForOrigin(gurl);
}

void ChildProcessSecurityPolicyImpl::LockToOrigin(int child_id,
                                                  const GURL& gurl) {
  // "gurl" can be currently empty in some cases, such as file://blah.
  DCHECK(SiteInstanceImpl::GetSiteForURL(NULL, gurl) == gurl);
  base::AutoLock lock(lock_);
  SecurityStateMap::iterator state = security_state_.find(child_id);
  DCHECK(state != security_state_.end());
  state->second->LockToOrigin(gurl);
}

void ChildProcessSecurityPolicyImpl::GrantPermissionsForFileSystem(
    int child_id,
    const std::string& filesystem_id,
    int permission) {
  base::AutoLock lock(lock_);

  SecurityStateMap::iterator state = security_state_.find(child_id);
  if (state == security_state_.end())
    return;
  state->second->GrantPermissionsForFileSystem(filesystem_id, permission);
}

bool ChildProcessSecurityPolicyImpl::HasPermissionsForFileSystem(
    int child_id,
    const std::string& filesystem_id,
    int permission) {
  base::AutoLock lock(lock_);

  SecurityStateMap::iterator state = security_state_.find(child_id);
  if (state == security_state_.end())
    return false;
  return state->second->HasPermissionsForFileSystem(filesystem_id, permission);
}

void ChildProcessSecurityPolicyImpl::RegisterFileSystemPermissionPolicy(
    storage::FileSystemType type,
    int policy) {
  base::AutoLock lock(lock_);
  file_system_policy_map_[type] = policy;
}

bool ChildProcessSecurityPolicyImpl::CanSendMidiSysExMessage(int child_id) {
  base::AutoLock lock(lock_);

  SecurityStateMap::iterator state = security_state_.find(child_id);
  if (state == security_state_.end())
    return false;

  return state->second->can_send_midi_sysex();
}

}  // namespace content