virtiofs: exit QueryVirtiofsMountSource early if virtiofs disabled

src/linux/init/config.cpp

@@ -679,12 +679,7 @@ try
     //
 
     Config.FeatureFlags = Message->FeatureFlags;
-    char FeatureFlagsString[10];
-    snprintf(FeatureFlagsString, sizeof(FeatureFlagsString), "%x", Config.FeatureFlags.value());
-    if (setenv(WSL_FEATURE_FLAGS_ENV, FeatureFlagsString, 1) < 0)
-    {
-        LOG_ERROR("setenv failed {}", errno);
-    }
+    UtilSetFeatureFlags(Config.FeatureFlags.value());
 
     //
     // Determine the default UID which can be specified in /etc/wsl.conf.
@@ -2413,7 +2408,7 @@ try
 
             NewMountOptions = MountEntry.MountOptions;
             NewMountOptions += ',';
-            if (WSL_USE_VIRTIO_9P(Config))
+            if (WSL_USE_VIRTIO_9P())
             {
                 //
                 // Check if the existing mount is a drvfs mount that needs to be remounted.
@@ -2446,7 +2441,7 @@ try
                 NewMountOptions += ',';
             }
 
-            MountPlan9Share(NewSource, MountEntry.MountPoint, NewMountOptions.c_str(), Message->Admin, Config);
+            MountPlan9Share(NewSource, MountEntry.MountPoint, NewMountOptions.c_str(), Message->Admin);
         }
         else if (strcmp(MountEntry.FileSystemType, VIRTIO_FS_TYPE) == 0)
         {

src/linux/init/config.h

@@ -23,8 +23,8 @@ Abstract:
 #include "SocketChannel.h"
 #include "WslDistributionConfig.h"
 
-#define WSL_USE_VIRTIO_9P(_Config) (WI_IsFlagSet(UtilGetFeatureFlags((_Config)), LxInitFeatureVirtIo9p))
-#define WSL_USE_VIRTIO_FS(_Config) (WI_IsFlagSet(UtilGetFeatureFlags((_Config)), LxInitFeatureVirtIoFs))
+#define WSL_USE_VIRTIO_9P() (WI_IsFlagSet(UtilGetFeatureFlags(), LxInitFeatureVirtIo9p))
+#define WSL_USE_VIRTIO_FS() (WI_IsFlagSet(UtilGetFeatureFlags(), LxInitFeatureVirtIoFs))
 #define WSLG_SHARED_FOLDER "wslg"
 
 #define INIT_MAKE_SECURITY(_uid, _gid, _mode) {_uid, _gid, _mode}

src/linux/init/drvfs.cpp

@@ -298,7 +298,7 @@ try
     {
         return MountFilesystem(DRVFS_FS_TYPE, Source, Target, Options, ExitCode);
     }
-    else if (WSL_USE_VIRTIO_FS(Config))
+    else if (WSL_USE_VIRTIO_FS())
     {
         return MountVirtioFs(Source, Target, Options, Admin, Config, ExitCode);
     }
@@ -349,7 +349,7 @@ Return Value:
     return ExitCode;
 }
 
-int MountPlan9Share(const char* Source, const char* Target, const char* Options, bool Admin, const wsl::linux::WslDistributionConfig& Config, int* ExitCode)
+int MountPlan9Share(const char* Source, const char* Target, const char* Options, bool Admin, int* ExitCode)
 
 /*++
 
@@ -367,8 +367,6 @@ Arguments:
 
     Admin - Supplies a boolean specifying if the admin share should be used.
 
-    Config - Supplies the distribution configuration.
-
     ExitCode - Supplies an optional pointer that receives the exit code.
 
 Return Value:
@@ -379,7 +377,7 @@ Return Value:
 
 {
     std::string MountOptions;
-    if (WSL_USE_VIRTIO_9P(Config))
+    if (WSL_USE_VIRTIO_9P())
     {
         Source = Admin ? LX_INIT_DRVFS_ADMIN_VIRTIO_TAG : LX_INIT_DRVFS_VIRTIO_TAG;
         MountOptions = std::format("msize=262144,trans=virtio,{}", Options);
@@ -476,7 +474,7 @@ try
     //
 
     MountOptions += Plan9Options;
-    if (MountPlan9Share(Source, Target, MountOptions.c_str(), Elevated, Config, ExitCode) < 0)
+    if (MountPlan9Share(Source, Target, MountOptions.c_str(), Elevated, ExitCode) < 0)
     {
         return -1;
     }
@@ -515,6 +513,8 @@ Return Value:
 
 try
 {
+    assert(WSL_USE_VIRTIO_FS());
+
     //
     // Check whether to use the elevated or non-elevated virtiofs server.
     //
@@ -596,6 +596,8 @@ Return Value:
 
 try
 {
+    assert(WSL_USE_VIRTIO_FS());
+
     wsl::shared::MessageWriter<LX_INIT_REMOUNT_VIRTIOFS_SHARE_MESSAGE> RemountShare(LxInitMessageRemountVirtioFsDevice);
     RemountShare->Admin = Admin;
     RemountShare.WriteString(RemountShare->TagOffset, Tag);
@@ -643,6 +645,21 @@ Return Value:
 
 try
 {
+    if (!WSL_USE_VIRTIO_FS())
+    {
+        return {};
+    }
+
+    //
+    // Validate the tag is a GUID.
+    //
+
+    const auto Guid = wsl::shared::string::ToGuid(Tag);
+    if (!Guid)
+    {
+        return {};
+    }
+
     wsl::shared::MessageWriter<LX_INIT_QUERY_VIRTIOFS_SHARE_MESSAGE> QueryShare(LxInitMessageQueryVirtioFsDevice);
     QueryShare.WriteString(QueryShare->TagOffset, Tag);
 

src/linux/init/drvfs.h

@@ -23,7 +23,7 @@ int MountDrvfs(const char* Source, const char* Target, const char* Options, std:
 
 int MountDrvfsEntry(int Argc, char* Argv[]);
 
-int MountPlan9Share(const char* Source, const char* Target, const char* Options, bool Admin, const wsl::linux::WslDistributionConfig& Config, int* ExitCode = nullptr);
+int MountPlan9Share(const char* Source, const char* Target, const char* Options, bool Admin, int* ExitCode = nullptr);
 
 int MountPlan9(const char* Source, const char* Target, const char* Options, std::optional<bool> Admin, const wsl::linux::WslDistributionConfig& Config, int* ExitCode);
 

src/linux/init/util.cpp

@@ -53,6 +53,7 @@ Abstract:
 #define WSL_MOUNT_OPTION_SEP ','
 
 int g_IsVmMode = -1;
+static std::optional<int> g_CachedFeatureFlags;
 static sigset_t g_originalSignals;
 thread_local std::string g_threadName;
 
@@ -1119,7 +1120,7 @@ catch (...)
     return {};
 }
 
-int UtilGetFeatureFlags(const wsl::linux::WslDistributionConfig& Config)
+int UtilGetFeatureFlags()
 
 /*++
 
@@ -1130,7 +1131,7 @@ Routine Description:
 
 Arguments:
 
-    Config - Supplies the distribution config.
+    None.
 
 Return Value:
 
@@ -1143,21 +1144,11 @@ Return Value:
     // If feature flags are already known, return them.
     //
 
-    static std::optional<int> g_CachedFeatureFlags;
     if (g_CachedFeatureFlags)
     {
         return *g_CachedFeatureFlags;
     }
 
-    //
-    // If an error occurs, just return no features.
-    //
-
-    if (Config.FeatureFlags.has_value())
-    {
-        return Config.FeatureFlags.value();
-    }
-
     //
     // Check if the environment variable is present.
     //
@@ -1167,9 +1158,7 @@ Return Value:
     //
 
     int FeatureFlags = LxInitFeatureNone;
-
     const char* FeatureFlagEnv = getenv(WSL_FEATURE_FLAGS_ENV);
-
     if (FeatureFlagEnv != nullptr)
     {
         FeatureFlags = strtol(FeatureFlagEnv, nullptr, 16);
@@ -1177,7 +1166,7 @@ Return Value:
     else
     {
         //
-        // Query init for the value.
+        // Query init for the value. If an error occurs, just return no features.
         //
 
         wsl::shared::SocketChannel channel{UtilConnectUnix(WSL_INIT_INTEROP_SOCKET), "wslinfo"};
@@ -1194,10 +1183,44 @@ Return Value:
         FeatureFlags = channel.ReceiveMessage<RESULT_MESSAGE<int32_t>>().Result;
     }
 
-    g_CachedFeatureFlags = FeatureFlags;
+    UtilSetFeatureFlags(FeatureFlags, FeatureFlagEnv == nullptr);
     return FeatureFlags;
 }
 
+void UtilSetFeatureFlags(int FeatureFlags, bool UpdateEnv)
+
+/*++
+
+Routine Description:
+
+    This routine sets the feature flags and updates the cached value and environment variable.
+
+Arguments:
+
+    FeatureFlags - Supplies the feature flags to set.
+
+    UpdateEnv - Supplies a boolean that indicates whether the environment variable should be updated.
+
+Return Value:
+
+    None.
+
+--*/
+
+try
+{
+    g_CachedFeatureFlags = FeatureFlags;
+    if (UpdateEnv)
+    {
+        auto FeatureFlagsString = std::format("{:x}", FeatureFlags);
+        if (setenv(WSL_FEATURE_FLAGS_ENV, FeatureFlagsString.c_str(), 1) < 0)
+        {
+            LOG_ERROR("setenv({}, {}, 1) failed {}", WSL_FEATURE_FLAGS_ENV, FeatureFlagsString, errno);
+        }
+    }
+}
+CATCH_LOG()
+
 std::optional<LX_MINI_INIT_NETWORKING_MODE> UtilGetNetworkingMode(void)
 
 /*++

src/linux/init/util.h

@@ -223,7 +223,9 @@ std::optional<std::string> UtilGetEnv(const char* Name, char* Environment);
 
 std::string UtilGetEnvironmentVariable(const char* Name);
 
-int UtilGetFeatureFlags(const wsl::linux::WslDistributionConfig& Config);
+int UtilGetFeatureFlags();
+
+void UtilSetFeatureFlags(int FeatureFlags, bool UpdateEnv = true);
 
 std::optional<LX_MINI_INIT_NETWORKING_MODE> UtilGetNetworkingMode(void);