| 1 | /*++ |
| 2 | |
| 3 | Copyright (c) Microsoft. All rights reserved. |
| 4 | |
| 5 | Module Name: |
| 6 | |
| 7 | wslpolicies.h |
| 8 | |
| 9 | Abstract: |
| 10 | |
| 11 | This file contains a helpers for querying WSL policies. |
| 12 | |
| 13 | --*/ |
| 14 | |
| 15 | #pragma once |
| 16 | |
| 17 | #include "registry.hpp" |
| 18 | |
| 19 | #define ROOT_POLICIES_KEY L"Software\\Policies" |
| 20 | |
| 21 | namespace wsl::windows::policies { |
| 22 | inline constexpr auto c_registryKey = ROOT_POLICIES_KEY L"\\WSL"; |
| 23 | inline constexpr auto c_allowInboxWSL = L"AllowInboxWSL"; |
| 24 | inline constexpr auto c_allowWSL = L"AllowWSL"; |
| 25 | inline constexpr auto c_allowWSL1 = L"AllowWSL1"; |
| 26 | inline constexpr auto c_allowCustomKernelUserSetting = L"AllowKernelUserSetting"; |
| 27 | inline constexpr auto c_allowCustomSystemDistroUserSetting = L"AllowSystemDistroUserSetting"; |
| 28 | inline constexpr auto c_allowCustomKernelCommandLineUserSetting = L"AllowKernelCommandLineUserSetting"; |
| 29 | inline constexpr auto c_allowDebugShellUserSetting = L"AllowDebugShell"; |
| 30 | inline constexpr auto c_allowNestedVirtualizationUserSetting = L"AllowNestedVirtualization"; |
| 31 | inline constexpr auto c_allowKernelDebuggingUserSetting = L"AllowKernelDebugUserSetting"; |
| 32 | inline constexpr auto c_allowDiskMount = L"AllowDiskMount"; |
| 33 | inline constexpr auto c_allowCustomNetworkingModeUserSetting = L"AllowNetworkingModeUserSetting"; |
| 34 | inline constexpr auto c_allowCustomFirewallUserSetting = L"AllowFirewallUserSetting"; |
| 35 | inline constexpr auto c_defaultNetworkingMode = L"DefaultNetworkingMode"; |
| 36 | inline constexpr auto c_allowWSLContainer = L"AllowWSLContainer"; |
| 37 | inline constexpr auto c_allowWSLContainerPrivileged = L"AllowWSLContainerPrivileged"; |
| 38 | inline constexpr auto c_wslContainerRegistryAllowlist = L"WSLContainerRegistryAllowlist"; |
| 39 | |
| 40 | inline std::optional<DWORD> GetPolicyValue(HKEY key, LPCWSTR name) |
| 41 | try |
| 42 | { |
| 43 | if (key == nullptr) |
| 44 | { |
| 45 | return std::nullopt; |
| 46 | } |
| 47 | |
| 48 | DWORD value = 0; |
| 49 | DWORD size = sizeof(value); |
| 50 | const LONG result = RegGetValueW(key, nullptr, name, RRF_RT_REG_DWORD, nullptr, &value, &size); |
| 51 | if (result == ERROR_PATH_NOT_FOUND || result == ERROR_FILE_NOT_FOUND) |
| 52 | { |
| 53 | return std::nullopt; |
| 54 | } |
| 55 | |
| 56 | THROW_IF_WIN32_ERROR(result); |
| 57 | |
| 58 | return value; |
| 59 | } |
| 60 | catch (...) |
| 61 | { |
| 62 | LOG_CAUGHT_EXCEPTION_MSG("Error reading the policy value: %ls", name); |
| 63 | return std::nullopt; |
| 64 | } |
| 65 | |
| 66 | inline bool IsFeatureAllowed(HKEY key, LPCWSTR name) |
| 67 | try |
| 68 | { |
| 69 | const auto policy = GetPolicyValue(key, name); |
| 70 | if (!policy.has_value()) |
| 71 | { |
| 72 | return true; |
| 73 | } |
| 74 | |
| 75 | const auto value = policy.value(); |
| 76 | THROW_HR_IF_MSG(E_UNEXPECTED, value != 0 && value != 1, "Invalid value for policy: %ls: %lu", name, value); |
| 77 | |
| 78 | return value == 1; |
| 79 | } |
| 80 | catch (...) |
| 81 | { |
| 82 | LOG_CAUGHT_EXCEPTION(); |
| 83 | return true; |
| 84 | } |
| 85 | |
| 86 | inline wil::unique_hkey OpenPoliciesKey() |
| 87 | { |
| 88 | wil::unique_hkey key; |
| 89 | const auto result = RegOpenKeyExW(HKEY_LOCAL_MACHINE, c_registryKey, 0, KEY_READ, &key); |
| 90 | if (result == ERROR_PATH_NOT_FOUND || result == ERROR_FILE_NOT_FOUND) |
| 91 | { |
| 92 | // N.B. Return an empty result if the registry key doesn't exist to make it easier |
| 93 | // to check for policies without having a special code path for this case. |
| 94 | return {}; |
| 95 | } |
| 96 | |
| 97 | LOG_IF_WIN32_ERROR(result); |
| 98 | return key; |
| 99 | } |
| 100 | |
| 101 | // Opens the WSLContainerRegistryAllowlist sub-key under the supplied policies key for |
| 102 | // read-only enumeration. Returns an empty handle when the policy is not configured (sub-key |
| 103 | // absent) or the parent key is null. |
| 104 | inline wil::unique_hkey OpenRegistryAllowlistKey(HKEY policiesKey) |
| 105 | { |
| 106 | if (policiesKey == nullptr) |
| 107 | { |
| 108 | return {}; |
| 109 | } |
| 110 | |
| 111 | wil::unique_hkey subKey; |
| 112 | const auto result = RegOpenKeyExW(policiesKey, c_wslContainerRegistryAllowlist, 0, KEY_READ, &subKey); |
| 113 | if (result == ERROR_PATH_NOT_FOUND || result == ERROR_FILE_NOT_FOUND) |
| 114 | { |
| 115 | return {}; |
| 116 | } |
| 117 | |
| 118 | LOG_IF_WIN32_ERROR(result); |
| 119 | return subKey; |
| 120 | } |
| 121 | |
| 122 | // Returns the REG_SZ data of every value under the WSLContainerRegistryAllowlist sub-key |
| 123 | // (one entry per configured registry hostname). The ADMX uses |
| 124 | // `<list valuePrefix="AllowedRegistry"/>`, which the GP editor materialises by writing one |
| 125 | // REG_SZ value per entry: each value is named `AllowedRegistry1`, `AllowedRegistry2`, ... and |
| 126 | // the value's data is the actual hostname; the value names are therefore ignored here. Schema |
| 127 | // reference: https://learn.microsoft.com/en-us/previous-versions/windows/desktop/Policy/element-list |
| 128 | // |
| 129 | // Returns an empty list when the sub-key has no values or on any enumeration failure; either |
| 130 | // case means no effective restriction is in place. |
| 131 | inline std::vector<std::wstring> EnumerateRegistryAllowlist(HKEY subKey) |
| 132 | try |
| 133 | { |
| 134 | std::vector<std::wstring> entries; |
| 135 | if (subKey == nullptr) |
| 136 | { |
| 137 | return entries; |
| 138 | } |
| 139 | |
| 140 | for (auto& [name, value] : wsl::windows::common::registry::EnumStringValues(subKey)) |
| 141 | { |
| 142 | // Skip empty entries so a stray blank list item in the GP editor doesn't make the |
| 143 | // allowlist non-empty (which would otherwise deny every registry). |
| 144 | if (value.empty()) |
| 145 | { |
| 146 | continue; |
| 147 | } |
| 148 | |
| 149 | entries.emplace_back(std::move(value)); |
| 150 | } |
| 151 | |
| 152 | return entries; |
| 153 | } |
| 154 | catch (...) |
| 155 | { |
| 156 | LOG_CAUGHT_EXCEPTION(); |
| 157 | return {}; |
| 158 | } |
| 159 | |
| 160 | // Evaluates the WSLContainerRegistryAllowlist policy for `server`. The policy only restricts |
| 161 | // traffic when the sub-key exists and contains at least one entry. With the sub-key absent or |
| 162 | // empty, every server is allowed; otherwise the server is allowed only when it case-insensitively |
| 163 | // matches one of the allowlist entries. |
| 164 | inline bool IsRegistryAllowed(HKEY policiesKey, std::wstring_view server) |
| 165 | { |
| 166 | auto subKey = OpenRegistryAllowlistKey(policiesKey); |
| 167 | if (!subKey) |
| 168 | { |
| 169 | return true; |
| 170 | } |
| 171 | |
| 172 | const auto entries = EnumerateRegistryAllowlist(subKey.get()); |
| 173 | if (entries.empty()) |
| 174 | { |
| 175 | return true; |
| 176 | } |
| 177 | |
| 178 | if (server.empty()) |
| 179 | { |
| 180 | return true; |
| 181 | } |
| 182 | |
| 183 | const std::wstring target{server}; |
| 184 | for (const auto& entry : entries) |
| 185 | { |
| 186 | if (_wcsicmp(entry.c_str(), target.c_str()) == 0) |
| 187 | { |
| 188 | return true; |
| 189 | } |
| 190 | } |
| 191 | return false; |
| 192 | } |
| 193 | |
| 194 | // Returns true when the WSLContainerRegistryAllowlist policy is in effect (sub-key present |
| 195 | // with at least one entry). Used by callers (e.g., `wslc image build`) that cannot attribute |
| 196 | // traffic to a specific registry and must therefore refuse the operation whenever any |
| 197 | // allowlist restriction is active. |
| 198 | inline bool HasRegistryAllowlist(HKEY policiesKey) |
| 199 | { |
| 200 | auto subKey = OpenRegistryAllowlistKey(policiesKey); |
| 201 | return subKey && !EnumerateRegistryAllowlist(subKey.get()).empty(); |
| 202 | } |
| 203 | |
| 204 | // Snapshot of the WSLContainerRegistryAllowlist policy captured in a single read. Callers use |
| 205 | // State to distinguish an unconfigured policy (fail open) from a policy that is present. |
| 206 | enum class RegistryAllowlistState |
| 207 | { |
| 208 | NotConfigured, |
| 209 | Configured |
| 210 | }; |
| 211 | |
| 212 | struct RegistryAllowlistSnapshot |
| 213 | { |
| 214 | RegistryAllowlistState State{RegistryAllowlistState::NotConfigured}; |
| 215 | std::vector<std::wstring> Hosts{}; |
| 216 | }; |
| 217 | |
| 218 | // subKey must be the WSLContainerRegistryAllowlist sub-key; enumeration failures throw MessageRegistryAllowlistPolicyInvalid. |
| 219 | inline RegistryAllowlistSnapshot ReadRegistryAllowlistSnapshot(HKEY subKey) |
| 220 | try |
| 221 | { |
| 222 | RegistryAllowlistSnapshot snapshot; |
| 223 | for (auto& [name, value] : wsl::windows::common::registry::EnumStringValues(subKey)) |
| 224 | { |
| 225 | if (value.empty()) |
| 226 | { |
| 227 | continue; |
| 228 | } |
| 229 | |
| 230 | snapshot.Hosts.emplace_back(std::move(value)); |
| 231 | } |
| 232 | |
| 233 | if (!snapshot.Hosts.empty()) |
| 234 | { |
| 235 | snapshot.State = RegistryAllowlistState::Configured; |
| 236 | } |
| 237 | |
| 238 | return snapshot; |
| 239 | } |
| 240 | catch (...) |
| 241 | { |
| 242 | LOG_CAUGHT_EXCEPTION(); |
| 243 | THROW_HR_WITH_USER_ERROR(wil::ResultFromCaughtException(), wsl::shared::Localization::MessageRegistryAllowlistPolicyInvalid()); |
| 244 | } |
| 245 | |
| 246 | // Throws MessageRegistryAllowlistPolicyInvalid on an unreadable sub-key so callers fail closed. |
| 247 | inline RegistryAllowlistSnapshot ReadRegistryAllowlistSnapshotFromPoliciesRoot() |
| 248 | { |
| 249 | const auto subKeyPath = std::wstring{c_registryKey} + L"\\" + c_wslContainerRegistryAllowlist; |
| 250 | wil::unique_hkey subKey; |
| 251 | const auto openResult = RegOpenKeyExW(HKEY_LOCAL_MACHINE, subKeyPath.c_str(), 0, KEY_READ, &subKey); |
| 252 | if (openResult == ERROR_PATH_NOT_FOUND || openResult == ERROR_FILE_NOT_FOUND) |
| 253 | { |
| 254 | return {}; |
| 255 | } |
| 256 | |
| 257 | THROW_HR_WITH_USER_ERROR_IF( |
| 258 | HRESULT_FROM_WIN32(openResult), wsl::shared::Localization::MessageRegistryAllowlistPolicyInvalid(), openResult != ERROR_SUCCESS); |
| 259 | |
| 260 | return ReadRegistryAllowlistSnapshot(subKey.get()); |
| 261 | } |
| 262 | |
| 263 | } // namespace wsl::windows::policies |