# HG changeset patch # User Bob Owen # Date 1631294898 -3600 # Fri Sep 10 18:28:18 2021 +0100 # Node ID adbc9b3051ab7f3c9360f65fe0fc26bd9d9dd499 # Parent 004b5bea4e78db7ecd665173ce4cf6aa0a1af199 Bug 1695556 p1: Allow reparse points in chromium sandbox code. Differential Revision: https://phabricator.services.mozilla.com/D135692 diff --git a/security/sandbox/chromium/sandbox/win/src/filesystem_dispatcher.cc b/security/sandbox/chromium/sandbox/win/src/filesystem_dispatcher.cc --- a/security/sandbox/chromium/sandbox/win/src/filesystem_dispatcher.cc +++ b/security/sandbox/chromium/sandbox/win/src/filesystem_dispatcher.cc @@ -87,17 +87,16 @@ bool FilesystemDispatcher::NtCreateFile( std::wstring* name, uint32_t attributes, uint32_t desired_access, uint32_t file_attributes, uint32_t share_access, uint32_t create_disposition, uint32_t create_options) { if (!PreProcessName(name)) { - // The path requested might contain a reparse point. ipc->return_info.nt_status = STATUS_ACCESS_DENIED; return true; } const wchar_t* filename = name->c_str(); uint32_t broker = BROKER_TRUE; CountedParameterSet params; @@ -141,17 +140,16 @@ bool FilesystemDispatcher::NtCreateFile( bool FilesystemDispatcher::NtOpenFile(IPCInfo* ipc, std::wstring* name, uint32_t attributes, uint32_t desired_access, uint32_t share_access, uint32_t open_options) { if (!PreProcessName(name)) { - // The path requested might contain a reparse point. ipc->return_info.nt_status = STATUS_ACCESS_DENIED; return true; } const wchar_t* filename = name->c_str(); uint32_t broker = BROKER_TRUE; uint32_t create_disposition = FILE_OPEN; @@ -196,17 +194,16 @@ bool FilesystemDispatcher::NtOpenFile(IP bool FilesystemDispatcher::NtQueryAttributesFile(IPCInfo* ipc, std::wstring* name, uint32_t attributes, CountedBuffer* info) { if (sizeof(FILE_BASIC_INFORMATION) != info->Size()) return false; if (!PreProcessName(name)) { - // The path requested might contain a reparse point. ipc->return_info.nt_status = STATUS_ACCESS_DENIED; return true; } uint32_t broker = BROKER_TRUE; const wchar_t* filename = name->c_str(); CountedParameterSet params; params[FileName::NAME] = ParamPickerMake(filename); @@ -245,17 +242,16 @@ bool FilesystemDispatcher::NtQueryAttrib bool FilesystemDispatcher::NtQueryFullAttributesFile(IPCInfo* ipc, std::wstring* name, uint32_t attributes, CountedBuffer* info) { if (sizeof(FILE_NETWORK_OPEN_INFORMATION) != info->Size()) return false; if (!PreProcessName(name)) { - // The path requested might contain a reparse point. ipc->return_info.nt_status = STATUS_ACCESS_DENIED; return true; } uint32_t broker = BROKER_TRUE; const wchar_t* filename = name->c_str(); CountedParameterSet params; params[FileName::NAME] = ParamPickerMake(filename); @@ -307,17 +303,16 @@ bool FilesystemDispatcher::NtSetInformat if (!IsSupportedRenameCall(rename_info, length, info_class)) return false; std::wstring name; name.assign(rename_info->FileName, rename_info->FileNameLength / sizeof(rename_info->FileName[0])); if (!PreProcessName(&name)) { - // The path requested might contain a reparse point. ipc->return_info.nt_status = STATUS_ACCESS_DENIED; return true; } uint32_t broker = BROKER_TRUE; const wchar_t* filename = name.c_str(); CountedParameterSet params; params[FileName::NAME] = ParamPickerMake(filename); diff --git a/security/sandbox/chromium/sandbox/win/src/filesystem_policy.cc b/security/sandbox/chromium/sandbox/win/src/filesystem_policy.cc --- a/security/sandbox/chromium/sandbox/win/src/filesystem_policy.cc +++ b/security/sandbox/chromium/sandbox/win/src/filesystem_policy.cc @@ -1,16 +1,17 @@ // Copyright (c) 2011 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 "sandbox/win/src/filesystem_policy.h" #include +#include #include #include "base/logging.h" #include "base/stl_util.h" #include "base/win/scoped_handle.h" #include "base/win/windows_version.h" #include "sandbox/win/src/ipc_tags.h" #include "sandbox/win/src/policy_engine_opcodes.h" @@ -39,22 +40,16 @@ NTSTATUS NtCreateFileInTarget(HANDLE* ta NTSTATUS status = NtCreateFile(&local_handle, desired_access, obj_attributes, io_status_block, nullptr, file_attributes, share_access, create_disposition, create_options, ea_buffer, ea_length); if (!NT_SUCCESS(status)) { return status; } - if (!sandbox::SameObject(local_handle, obj_attributes->ObjectName->Buffer)) { - // The handle points somewhere else. Fail the operation. - ::CloseHandle(local_handle); - return STATUS_ACCESS_DENIED; - } - if (!::DuplicateHandle(::GetCurrentProcess(), local_handle, target_process, target_file_handle, 0, false, DUPLICATE_CLOSE_SOURCE | DUPLICATE_SAME_ACCESS)) { return STATUS_ACCESS_DENIED; } return STATUS_SUCCESS; } @@ -400,23 +395,32 @@ bool FileSystemPolicy::SetInformationFil static_cast(info_class); *nt_status = NtSetInformationFile(local_handle, io_block, file_info, length, file_info_class); return true; } bool PreProcessName(std::wstring* path) { - ConvertToLongPath(path); + // We now allow symbolic links to be opened via the broker, so we can no + // longer rely on the same object check where we checked the path of the + // opened file against the original. We don't specify a root when creating + // OBJECT_ATTRIBUTES from file names for brokering so they must be fully + // qualified and we can just check for the parent directory double dot between + // two backslashes. NtCreateFile doesn't seem to allow it anyway, but this is + // just an extra precaution. It also doesn't seem to allow the forward slash, + // but this is also used for checking policy rules, so we just replace forward + // slashes with backslashes. + std::replace(path->begin(), path->end(), L'/', L'\\'); + if (path->find(L"\\..\\") != std::wstring::npos) { + return false; + } - if (ERROR_NOT_A_REPARSE_POINT == IsReparsePoint(*path)) - return true; - - // We can't process a reparsed file. - return false; + ConvertToLongPath(path); + return true; } std::wstring FixNTPrefixForMatch(const std::wstring& name) { std::wstring mod_name = name; // NT prefix escaped for rule matcher const wchar_t kNTPrefixEscaped[] = L"\\/?/?\\"; const int kNTPrefixEscapedLen = base::size(kNTPrefixEscaped) - 1;