qga-pull-2023-07-10

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Merge tag 'qga-pull-2023-07-10' of https://github.com/kostyanf14/qemu into staging

qga-pull-2023-07-10

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# gpg: Signature made Mon 10 Jul 2023 02:17:19 PM BST
# gpg:                using RSA key C2C2C109EA43C63C1423EB84EF5D5E8161BA84E7
# gpg: Good signature from "Kostiantyn Kostiuk (Upstream PR sign) <kkostiuk@redhat.com>" [unknown]
# gpg: WARNING: This key is not certified with a trusted signature!
# gpg:          There is no indication that the signature belongs to the owner.
# Primary key fingerprint: C2C2 C109 EA43 C63C 1423  EB84 EF5D 5E81 61BA 84E7

* tag 'qga-pull-2023-07-10' of https://github.com/kostyanf14/qemu:
  QGA VSS: Add log in functions begin/end
  QGA VSS: Print error in err_set
  QGA VSS: Replace 'fprintf(stderr' with qga_debug
  QGA VSS: Add wrapper to send log to debugger and stderr
  qga: Add tests for --allow-rpcs option
  qga: Add new option --allow-rpcs
  qga: Rename ga_disable_not_allowed -> ga_disable_not_allowed_freeze

Signed-off-by: Richard Henderson <richard.henderson@linaro.org>

docs/interop/qemu-ga.rst

@@ -84,6 +84,11 @@ Options
   Comma-separated list of RPCs to disable (no spaces, use ``help`` to
   list available RPCs).
 
+.. option:: -a, --allow-rpcs=LIST
+
+  Comma-separated list of RPCs to enable (no spaces, use ``help`` to
+  list available RPCs).
+
 .. option:: -D, --dump-conf
 
   Dump the configuration in a format compatible with ``qemu-ga.conf``

qga/main.c

@@ -87,6 +87,7 @@ struct GAState {
     bool delimit_response;
     bool frozen;
     GList *blockedrpcs;
+    GList *allowedrpcs;
     char *state_filepath_isfrozen;
     struct {
         const char *log_filepath;
@@ -261,6 +262,8 @@ QEMU_COPYRIGHT "\n"
 #endif
 "  -b, --block-rpcs  comma-separated list of RPCs to disable (no spaces,\n"
 "                    use \"help\" to list available RPCs)\n"
+"  -a, --allow-rpcs  comma-separated list of RPCs to enable (no spaces,\n"
+"                    use \"help\" to list available RPCs)\n"
 "  -D, --dump-conf   dump a qemu-ga config file based on current config\n"
 "                    options / command-line parameters to stdout\n"
 "  -r, --retry-path  attempt re-opening path if it's unavailable or closed\n"
@@ -395,7 +398,7 @@ static gint ga_strcmp(gconstpointer str1, gconstpointer str2)
 }
 
 /* disable commands that aren't safe for fsfreeze */
-static void ga_disable_not_allowed(const QmpCommand *cmd, void *opaque)
+static void ga_disable_not_allowed_freeze(const QmpCommand *cmd, void *opaque)
 {
     bool allowed = false;
     int i = 0;
@@ -416,16 +419,38 @@ static void ga_disable_not_allowed(const QmpCommand *cmd, void *opaque)
 /* [re-]enable all commands, except those explicitly blocked by user */
 static void ga_enable_non_blocked(const QmpCommand *cmd, void *opaque)
 {
-    GList *blockedrpcs = opaque;
+    GAState *s = opaque;
+    GList *blockedrpcs = s->blockedrpcs;
+    GList *allowedrpcs = s->allowedrpcs;
     const char *name = qmp_command_name(cmd);
 
-    if (g_list_find_custom(blockedrpcs, name, ga_strcmp) == NULL &&
+    if (g_list_find_custom(blockedrpcs, name, ga_strcmp) == NULL) {
-        !qmp_command_is_enabled(cmd)) {
+        if (qmp_command_is_enabled(cmd)) {
+            return;
+        }
+
+        if (allowedrpcs &&
+            g_list_find_custom(allowedrpcs, name, ga_strcmp) == NULL) {
+            return;
+        }
+
         g_debug("enabling command: %s", name);
         qmp_enable_command(&ga_commands, name);
     }
 }
 
+/* disable commands that aren't allowed */
+static void ga_disable_not_allowed(const QmpCommand *cmd, void *opaque)
+{
+    GList *allowedrpcs = opaque;
+    const char *name = qmp_command_name(cmd);
+
+    if (g_list_find_custom(allowedrpcs, name, ga_strcmp) == NULL) {
+        g_debug("disabling command: %s", name);
+        qmp_disable_command(&ga_commands, name, "the command is not allowed");
+    }
+}
+
 static bool ga_create_file(const char *path)
 {
     int fd = open(path, O_CREAT | O_WRONLY, S_IWUSR | S_IRUSR);
@@ -459,7 +484,7 @@ void ga_set_frozen(GAState *s)
         return;
     }
     /* disable all forbidden (for frozen state) commands */
-    qmp_for_each_command(&ga_commands, ga_disable_not_allowed, NULL);
+    qmp_for_each_command(&ga_commands, ga_disable_not_allowed_freeze, NULL);
     g_warning("disabling logging due to filesystem freeze");
     ga_disable_logging(s);
     s->frozen = true;
@@ -497,8 +522,8 @@ void ga_unset_frozen(GAState *s)
         s->deferred_options.pid_filepath = NULL;
     }
 
-    /* enable all disabled, non-blocked commands */
+    /* enable all disabled, non-blocked and allowed commands */
-    qmp_for_each_command(&ga_commands, ga_enable_non_blocked, s->blockedrpcs);
+    qmp_for_each_command(&ga_commands, ga_enable_non_blocked, s);
     s->frozen = false;
     if (!ga_delete_file(s->state_filepath_isfrozen)) {
         g_warning("unable to delete %s, fsfreeze may not function properly",
@@ -984,7 +1009,9 @@ struct GAConfig {
     const char *service;
 #endif
     gchar *bliststr; /* blockedrpcs may point to this string */
+    gchar *aliststr; /* allowedrpcs may point to this string */
     GList *blockedrpcs;
+    GList *allowedrpcs;
     int daemonize;
     GLogLevelFlags log_level;
     int dumpconf;
@@ -1055,6 +1082,19 @@ static void config_load(GAConfig *config)
         config->blockedrpcs = g_list_concat(config->blockedrpcs,
                                           split_list(config->bliststr, ","));
     }
+    if (g_key_file_has_key(keyfile, "general", "allow-rpcs", NULL)) {
+        config->aliststr =
+            g_key_file_get_string(keyfile, "general", "allow-rpcs", &gerr);
+        config->allowedrpcs = g_list_concat(config->allowedrpcs,
+                                          split_list(config->aliststr, ","));
+    }
+
+    if (g_key_file_has_key(keyfile, "general", blockrpcs_key, NULL) &&
+        g_key_file_has_key(keyfile, "general", "allow-rpcs", NULL)) {
+        g_critical("wrong config, using 'block-rpcs' and 'allow-rpcs' keys at"
+                   " the same time is not allowed");
+        exit(EXIT_FAILURE);
+    }
 
 end:
     g_key_file_free(keyfile);
@@ -1115,6 +1155,9 @@ static void config_dump(GAConfig *config)
     tmp = list_join(config->blockedrpcs, ',');
     g_key_file_set_string(keyfile, "general", "block-rpcs", tmp);
     g_free(tmp);
+    tmp = list_join(config->allowedrpcs, ',');
+    g_key_file_set_string(keyfile, "general", "allow-rpcs", tmp);
+    g_free(tmp);
 
     tmp = g_key_file_to_data(keyfile, NULL, &error);
     if (error) {
@@ -1130,8 +1173,9 @@ static void config_dump(GAConfig *config)
 
 static void config_parse(GAConfig *config, int argc, char **argv)
 {
-    const char *sopt = "hVvdm:p:l:f:F::b:s:t:Dr";
+    const char *sopt = "hVvdm:p:l:f:F::b:a:s:t:Dr";
     int opt_ind = 0, ch;
+    bool block_rpcs = false, allow_rpcs = false;
     const struct option lopt[] = {
         { "help", 0, NULL, 'h' },
         { "version", 0, NULL, 'V' },
@@ -1147,6 +1191,7 @@ static void config_parse(GAConfig *config, int argc, char **argv)
         { "daemonize", 0, NULL, 'd' },
         { "block-rpcs", 1, NULL, 'b' },
         { "blacklist", 1, NULL, 'b' },  /* deprecated alias for 'block-rpcs' */
+        { "allow-rpcs", 1, NULL, 'a' },
 #ifdef _WIN32
         { "service", 1, NULL, 's' },
 #endif
@@ -1206,6 +1251,17 @@ static void config_parse(GAConfig *config, int argc, char **argv)
             }
             config->blockedrpcs = g_list_concat(config->blockedrpcs,
                                                 split_list(optarg, ","));
+            block_rpcs = true;
+            break;
+        }
+        case 'a': {
+            if (is_help_option(optarg)) {
+                qmp_for_each_command(&ga_commands, ga_print_cmd, NULL);
+                exit(EXIT_SUCCESS);
+            }
+            config->allowedrpcs = g_list_concat(config->allowedrpcs,
+                                                split_list(optarg, ","));
+            allow_rpcs = true;
             break;
         }
 #ifdef _WIN32
@@ -1246,6 +1302,12 @@ static void config_parse(GAConfig *config, int argc, char **argv)
             exit(EXIT_FAILURE);
         }
     }
+
+    if (block_rpcs && allow_rpcs) {
+        g_critical("wrong commandline, using --block-rpcs and --allow-rpcs at the"
+                   " same time is not allowed");
+        exit(EXIT_FAILURE);
+    }
 }
 
 static void config_free(GAConfig *config)
@@ -1256,10 +1318,12 @@ static void config_free(GAConfig *config)
     g_free(config->state_dir);
     g_free(config->channel_path);
     g_free(config->bliststr);
+    g_free(config->aliststr);
 #ifdef CONFIG_FSFREEZE
     g_free(config->fsfreeze_hook);
 #endif
     g_list_free_full(config->blockedrpcs, g_free);
+    g_list_free_full(config->allowedrpcs, g_free);
     g_free(config);
 }
 
@@ -1350,7 +1414,7 @@ static GAState *initialize_agent(GAConfig *config, int socket_activation)
             s->deferred_options.log_filepath = config->log_filepath;
         }
         ga_disable_logging(s);
-        qmp_for_each_command(&ga_commands, ga_disable_not_allowed, NULL);
+        qmp_for_each_command(&ga_commands, ga_disable_not_allowed_freeze, NULL);
     } else {
         if (config->daemonize) {
             become_daemon(config->pid_filepath);
@@ -1374,6 +1438,15 @@ static GAState *initialize_agent(GAConfig *config, int socket_activation)
         return NULL;
     }
 
+    if (config->allowedrpcs) {
+        qmp_for_each_command(&ga_commands, ga_disable_not_allowed, config->allowedrpcs);
+        s->allowedrpcs = config->allowedrpcs;
+    }
+
+    /*
+     * Some commands can be blocked due to system limitation.
+     * Initialize blockedrpcs list even if allowedrpcs specified.
+     */
     config->blockedrpcs = ga_command_init_blockedrpcs(config->blockedrpcs);
     if (config->blockedrpcs) {
         GList *l = config->blockedrpcs;

qga/vss-win32/install.cpp

@@ -13,6 +13,7 @@
 #include "qemu/osdep.h"
 
 #include "vss-common.h"
+#include "vss-debug.h"
 #ifdef HAVE_VSS_SDK
 #include <vscoordint.h>
 #else
@@ -54,7 +55,7 @@ void errmsg(DWORD err, const char *text)
                   FORMAT_MESSAGE_FROM_SYSTEM | FORMAT_MESSAGE_IGNORE_INSERTS,
                   NULL, err, MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT),
                   (char *)&msg, 0, NULL);
-    fprintf(stderr, "%.*s. (Error: %lx) %s\n", len, text, err, msg);
+    qga_debug("%.*s. (Error: %lx) %s", len, text, err, msg);
     LocalFree(msg);
 }
 
@@ -99,6 +100,8 @@ HRESULT put_Value(ICatalogObject *pObj, LPCWSTR name, T val)
 /* Lookup Administrators group name from winmgmt */
 static HRESULT GetAdminName(_bstr_t *name)
 {
+    qga_debug_begin;
+
     HRESULT hr;
     COMPointer<IWbemLocator> pLoc;
     COMPointer<IWbemServices> pSvc;
@@ -141,6 +144,7 @@ static HRESULT GetAdminName(_bstr_t *name)
     }
 
 out:
+    qga_debug_end;
     return hr;
 }
 
@@ -148,6 +152,8 @@ out:
 static HRESULT getNameByStringSID(
     const wchar_t *sid, LPWSTR buffer, LPDWORD bufferLen)
 {
+    qga_debug_begin;
+
     HRESULT hr = S_OK;
     PSID psid = NULL;
     SID_NAME_USE groupType;
@@ -167,6 +173,7 @@ static HRESULT getNameByStringSID(
     LocalFree(psid);
 
 out:
+    qga_debug_end;
     return hr;
 }
 
@@ -174,6 +181,8 @@ out:
 static HRESULT QGAProviderFind(
     HRESULT (*found)(ICatalogCollection *, int, void *), void *arg)
 {
+    qga_debug_begin;
+
     HRESULT hr;
     COMInitializer initializer;
     COMPointer<IUnknown> pUnknown;
@@ -204,41 +213,53 @@ static HRESULT QGAProviderFind(
     chk(pColl->SaveChanges(&n));
 
 out:
+    qga_debug_end;
     return hr;
 }
 
 /* Count QGA VSS provider in COM+ Application Catalog */
 static HRESULT QGAProviderCount(ICatalogCollection *coll, int i, void *arg)
 {
+    qga_debug_begin;
+
     (*(int *)arg)++;
+
+    qga_debug_end;
     return S_OK;
 }
 
 /* Remove QGA VSS provider from COM+ Application Catalog Collection */
 static HRESULT QGAProviderRemove(ICatalogCollection *coll, int i, void *arg)
 {
+    qga_debug_begin;
     HRESULT hr;
 
-    fprintf(stderr, "Removing COM+ Application: %s\n", QGA_PROVIDER_NAME);
+    qga_debug("Removing COM+ Application: %s", QGA_PROVIDER_NAME);
     chk(coll->Remove(i));
 out:
+    qga_debug_end;
     return hr;
 }
 
 /* Unregister this module from COM+ Applications Catalog */
 STDAPI COMUnregister(void)
 {
+    qga_debug_begin;
+
     HRESULT hr;
 
     DllUnregisterServer();
     chk(QGAProviderFind(QGAProviderRemove, NULL));
 out:
+    qga_debug_end;
     return hr;
 }
 
 /* Register this module to COM+ Applications Catalog */
 STDAPI COMRegister(void)
 {
+    qga_debug_begin;
+
     HRESULT hr;
     COMInitializer initializer;
     COMPointer<IUnknown> pUnknown;
@@ -258,12 +279,14 @@ STDAPI COMRegister(void)
 
     if (!g_hinstDll) {
         errmsg(E_FAIL, "Failed to initialize DLL");
+        qga_debug_end;
         return E_FAIL;
     }
 
     chk(QGAProviderFind(QGAProviderCount, (void *)&count));
     if (count) {
         errmsg(E_ABORT, "QGA VSS Provider is already installed");
+        qga_debug_end;
         return E_ABORT;
     }
 
@@ -304,9 +327,8 @@ STDAPI COMRegister(void)
     }
     strcpy(tlbPath, dllPath);
     strcpy(tlbPath+n-3, "tlb");
-    fprintf(stderr, "Registering " QGA_PROVIDER_NAME ":\n");
+    qga_debug("Registering " QGA_PROVIDER_NAME ": %s %s",
-    fprintf(stderr, "  %s\n", dllPath);
+              dllPath, tlbPath);
-    fprintf(stderr, "  %s\n", tlbPath);
     if (!PathFileExists(tlbPath)) {
         hr = HRESULT_FROM_WIN32(ERROR_FILE_NOT_FOUND);
         errmsg(hr, "Failed to lookup tlb");
@@ -354,6 +376,7 @@ out:
         COMUnregister();
     }
 
+    qga_debug_end;
     return hr;
 }
 
@@ -369,6 +392,8 @@ STDAPI_(void) CALLBACK DLLCOMUnregister(HWND, HINSTANCE, LPSTR, int)
 
 static BOOL CreateRegistryKey(LPCTSTR key, LPCTSTR value, LPCTSTR data)
 {
+    qga_debug_begin;
+
     HKEY  hKey;
     LONG  ret;
     DWORD size;
@@ -389,6 +414,7 @@ static BOOL CreateRegistryKey(LPCTSTR key, LPCTSTR value, LPCTSTR data)
     RegCloseKey(hKey);
 
 out:
+    qga_debug_end;
     if (ret != ERROR_SUCCESS) {
         /* As we cannot printf within DllRegisterServer(), show a dialog. */
         errmsg_dialog(ret, "Cannot add registry", key);
@@ -400,6 +426,8 @@ out:
 /* Register this dll as a VSS provider */
 STDAPI DllRegisterServer(void)
 {
+    qga_debug_begin;
+
     COMInitializer initializer;
     COMPointer<IVssAdmin> pVssAdmin;
     HRESULT hr = E_FAIL;
@@ -478,12 +506,15 @@ out:
         DllUnregisterServer();
     }
 
+    qga_debug_end;
     return hr;
 }
 
 /* Unregister this VSS hardware provider from the system */
 STDAPI DllUnregisterServer(void)
 {
+    qga_debug_begin;
+
     TCHAR key[256];
     COMInitializer initializer;
     COMPointer<IVssAdmin> pVssAdmin;
@@ -501,6 +532,7 @@ STDAPI DllUnregisterServer(void)
     SHDeleteKey(HKEY_CLASSES_ROOT, key);
     SHDeleteKey(HKEY_CLASSES_ROOT, g_szProgid);
 
+    qga_debug_end;
     return S_OK; /* Uninstall should never fail */
 }
 
@@ -517,7 +549,7 @@ namespace _com_util
         }
 
         if (mbstowcs(bstr, ascii, len) == (size_t)-1) {
-            fprintf(stderr, "Failed to convert string '%s' into BSTR", ascii);
+            qga_debug("Failed to convert string '%s' into BSTR", ascii);
             bstr[0] = 0;
         }
         return bstr;
@@ -527,6 +559,8 @@ namespace _com_util
 /* Stop QGA VSS provider service using Winsvc API  */
 STDAPI StopService(void)
 {
+    qga_debug_begin;
+
     HRESULT hr = S_OK;
     SC_HANDLE manager = OpenSCManager(NULL, NULL, SC_MANAGER_ALL_ACCESS);
     SC_HANDLE service = NULL;
@@ -551,5 +585,6 @@ STDAPI StopService(void)
 out:
     CloseServiceHandle(service);
     CloseServiceHandle(manager);
+    qga_debug_end;
     return hr;
 }

qga/vss-win32/meson.build

@@ -7,7 +7,7 @@ link_args = cc.get_supported_link_arguments([
 
 qga_vss = shared_module(
   'qga-vss',
-  ['requester.cpp', 'provider.cpp', 'install.cpp', genh],
+  ['requester.cpp', 'provider.cpp', 'install.cpp', 'vss-debug.cpp', genh],
   name_prefix: '',
   cpp_args: ['-Wno-unknown-pragmas', '-Wno-delete-non-virtual-dtor', '-Wno-non-virtual-dtor'],
   link_args: link_args,

qga/vss-win32/provider.cpp

@@ -12,6 +12,7 @@
 
 #include "qemu/osdep.h"
 #include "vss-common.h"
+#include "vss-debug.h"
 #ifdef HAVE_VSS_SDK
 #include <vscoordint.h>
 #else
@@ -529,9 +530,11 @@ STDAPI DllCanUnloadNow()
 EXTERN_C
 BOOL WINAPI DllMain(HINSTANCE hinstDll, DWORD dwReason, LPVOID lpReserved)
 {
+    qga_debug("begin, reason = %lu", dwReason);
     if (dwReason == DLL_PROCESS_ATTACH) {
         g_hinstDll = hinstDll;
         DisableThreadLibraryCalls(hinstDll);
     }
+    qga_debug_end;
     return TRUE;
 }

qga/vss-win32/requester.cpp

@@ -12,6 +12,7 @@
 
 #include "qemu/osdep.h"
 #include "vss-common.h"
+#include "vss-debug.h"
 #include "requester.h"
 #include "install.h"
 #include <vswriter.h>
@@ -25,9 +26,11 @@
 
 #define DEFAULT_VSS_BACKUP_TYPE VSS_BT_FULL
 
-#define err_set(e, err, fmt, ...)                                           \
+#define err_set(e, err, fmt, ...) {                                         \
-    ((e)->error_setg_win32_wrapper((e)->errp, __FILE__, __LINE__, __func__, \
+    (e)->error_setg_win32_wrapper((e)->errp, __FILE__, __LINE__, __func__,  \
-                                   err, fmt, ## __VA_ARGS__))
+                                   err, fmt, ## __VA_ARGS__);               \
+    qga_debug(fmt, ## __VA_ARGS__);                                         \
+}
 /* Bad idea, works only when (e)->errp != NULL: */
 #define err_is_set(e) ((e)->errp && *(e)->errp)
 /* To lift this restriction, error_propagate(), like we do in QEMU code */
@@ -54,18 +57,20 @@ static struct QGAVSSContext {
 
 STDAPI requester_init(void)
 {
+    qga_debug_begin;
+
     COMInitializer initializer; /* to call CoInitializeSecurity */
     HRESULT hr = CoInitializeSecurity(
         NULL, -1, NULL, NULL, RPC_C_AUTHN_LEVEL_PKT_PRIVACY,
         RPC_C_IMP_LEVEL_IDENTIFY, NULL, EOAC_NONE, NULL);
     if (FAILED(hr)) {
-        fprintf(stderr, "failed to CoInitializeSecurity (error %lx)\n", hr);
+        qga_debug("failed to CoInitializeSecurity (error %lx)", hr);
         return hr;
     }
 
     hLib = LoadLibraryA("VSSAPI.DLL");
     if (!hLib) {
-        fprintf(stderr, "failed to load VSSAPI.DLL\n");
+        qga_debug("failed to load VSSAPI.DLL");
         return HRESULT_FROM_WIN32(GetLastError());
     }
 
@@ -78,22 +83,25 @@ STDAPI requester_init(void)
 #endif
         );
     if (!pCreateVssBackupComponents) {
-        fprintf(stderr, "failed to get proc address from VSSAPI.DLL\n");
+        qga_debug("failed to get proc address from VSSAPI.DLL");
         return HRESULT_FROM_WIN32(GetLastError());
     }
 
     pVssFreeSnapshotProperties = (t_VssFreeSnapshotProperties)
         GetProcAddress(hLib, "VssFreeSnapshotProperties");
     if (!pVssFreeSnapshotProperties) {
-        fprintf(stderr, "failed to get proc address from VSSAPI.DLL\n");
+        qga_debug("failed to get proc address from VSSAPI.DLL");
         return HRESULT_FROM_WIN32(GetLastError());
     }
 
+    qga_debug_end;
     return S_OK;
 }
 
 static void requester_cleanup(void)
 {
+    qga_debug_begin;
+
     if (vss_ctx.hEventFrozen) {
         CloseHandle(vss_ctx.hEventFrozen);
         vss_ctx.hEventFrozen = NULL;
@@ -115,10 +123,13 @@ static void requester_cleanup(void)
         vss_ctx.pVssbc = NULL;
     }
     vss_ctx.cFrozenVols = 0;
+    qga_debug_end;
 }
 
 STDAPI requester_deinit(void)
 {
+    qga_debug_begin;
+
     requester_cleanup();
 
     pCreateVssBackupComponents = NULL;
@@ -128,11 +139,14 @@ STDAPI requester_deinit(void)
         hLib = NULL;
     }
 
+    qga_debug_end;
     return S_OK;
 }
 
 static HRESULT WaitForAsync(IVssAsync *pAsync)
 {
+    qga_debug_begin;
+
     HRESULT ret, hr;
 
     do {
@@ -148,11 +162,14 @@ static HRESULT WaitForAsync(IVssAsync *pAsync)
         }
     } while (ret == VSS_S_ASYNC_PENDING);
 
+    qga_debug_end;
     return ret;
 }
 
 static void AddComponents(ErrorSet *errset)
 {
+    qga_debug_begin;
+
     unsigned int cWriters, i;
     VSS_ID id, idInstance, idWriter;
     BSTR bstrWriterName = NULL;
@@ -234,17 +251,21 @@ out:
     if (pComponent && info) {
         pComponent->FreeComponentInfo(info);
     }
+    qga_debug_end;
 }
 
 DWORD get_reg_dword_value(HKEY baseKey, LPCSTR subKey, LPCSTR valueName,
                           DWORD defaultData)
 {
+    qga_debug_begin;
+
     DWORD regGetValueError;
     DWORD dwordData;
     DWORD dataSize = sizeof(DWORD);
 
     regGetValueError = RegGetValue(baseKey, subKey, valueName, RRF_RT_DWORD,
                                    NULL, &dwordData, &dataSize);
+    qga_debug_end;
     if (regGetValueError  != ERROR_SUCCESS) {
         return defaultData;
     }
@@ -259,6 +280,8 @@ bool is_valid_vss_backup_type(VSS_BACKUP_TYPE vssBT)
 VSS_BACKUP_TYPE get_vss_backup_type(
     VSS_BACKUP_TYPE defaultVssBT = DEFAULT_VSS_BACKUP_TYPE)
 {
+    qga_debug_begin;
+
     VSS_BACKUP_TYPE vssBackupType;
 
     vssBackupType = static_cast<VSS_BACKUP_TYPE>(
@@ -266,6 +289,7 @@ VSS_BACKUP_TYPE get_vss_backup_type(
                                                 QGA_PROVIDER_REGISTRY_ADDRESS,
                                                 "VssOption",
                                                 defaultVssBT));
+    qga_debug_end;
     if (!is_valid_vss_backup_type(vssBackupType)) {
         return defaultVssBT;
     }
@@ -274,6 +298,8 @@ VSS_BACKUP_TYPE get_vss_backup_type(
 
 void requester_freeze(int *num_vols, void *mountpoints, ErrorSet *errset)
 {
+    qga_debug_begin;
+
     COMPointer<IVssAsync> pAsync;
     HANDLE volume;
     HRESULT hr;
@@ -289,6 +315,7 @@ void requester_freeze(int *num_vols, void *mountpoints, ErrorSet *errset)
 
     if (vss_ctx.pVssbc) { /* already frozen */
         *num_vols = 0;
+        qga_debug("finished, already frozen");
         return;
     }
 
@@ -446,6 +473,7 @@ void requester_freeze(int *num_vols, void *mountpoints, ErrorSet *errset)
         }
     }
 
+    qga_debug("preparing for backup");
     hr = vss_ctx.pVssbc->PrepareForBackup(pAsync.replace());
     if (SUCCEEDED(hr)) {
         hr = WaitForAsync(pAsync);
@@ -469,6 +497,7 @@ void requester_freeze(int *num_vols, void *mountpoints, ErrorSet *errset)
      * CQGAVssProvider::CommitSnapshots will kick vss_ctx.hEventFrozen
      * after the applications and filesystems are frozen.
      */
+    qga_debug("do snapshot set");
     hr = vss_ctx.pVssbc->DoSnapshotSet(&vss_ctx.pAsyncSnapshot);
     if (FAILED(hr)) {
         err_set(errset, hr, "failed to do snapshot set");
@@ -515,6 +544,7 @@ void requester_freeze(int *num_vols, void *mountpoints, ErrorSet *errset)
         *num_vols = vss_ctx.cFrozenVols = num_fixed_drives;
     }
 
+    qga_debug("end successful");
     return;
 
 out:
@@ -525,11 +555,14 @@ out:
 out1:
     requester_cleanup();
     CoUninitialize();
+
+    qga_debug_end;
 }
 
 
 void requester_thaw(int *num_vols, void *mountpints, ErrorSet *errset)
 {
+    qga_debug_begin;
     COMPointer<IVssAsync> pAsync;
 
     if (!vss_ctx.hEventThaw) {
@@ -538,6 +571,8 @@ void requester_thaw(int *num_vols, void *mountpints, ErrorSet *errset)
          * and no volumes must be frozen. We return without an error.
          */
         *num_vols = 0;
+        qga_debug("finished, no volumes were frozen");
+
         return;
     }
 
@@ -594,4 +629,6 @@ void requester_thaw(int *num_vols, void *mountpints, ErrorSet *errset)
 
     CoUninitialize();
     StopService();
+
+    qga_debug_end;
 }

qga/vss-win32/vss-debug.cpp

@@ -0,0 +1,39 @@
+/*
+ * QEMU Guest Agent VSS debug declarations
+ *
+ * Copyright (C) 2023 Red Hat Inc
+ *
+ * Authors:
+ *  Konstantin Kostiuk <kkostiuk@redhat.com>
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2 or later.
+ * See the COPYING file in the top-level directory.
+ */
+
+#include "qemu/osdep.h"
+#include "vss-debug.h"
+#include "vss-common.h"
+
+void qga_debug_internal(const char *funcname, const char *fmt, ...)
+{
+    char user_string[512] = {0};
+    char full_string[640] = {0};
+
+    va_list args;
+    va_start(args, fmt);
+    if (vsnprintf(user_string, _countof(user_string), fmt, args) <= 0) {
+        va_end(args);
+        return;
+    }
+
+    va_end(args);
+
+    if (snprintf(full_string, _countof(full_string),
+                 QGA_PROVIDER_NAME "[%lu]: %s %s\n",
+                 GetCurrentThreadId(), funcname, user_string) <= 0) {
+        return;
+    }
+
+    OutputDebugString(full_string);
+    fputs(full_string, stderr);
+}

qga/vss-win32/vss-debug.h

@@ -0,0 +1,25 @@
+/*
+ * QEMU Guest Agent VSS debug declarations
+ *
+ * Copyright (C) 2023 Red Hat Inc
+ *
+ * Authors:
+ *  Konstantin Kostiuk <kkostiuk@redhat.com>
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2 or later.
+ * See the COPYING file in the top-level directory.
+ */
+
+#include "qemu/osdep.h"
+#include <vss-handles.h>
+
+#ifndef VSS_DEBUG_H
+#define VSS_DEBUG_H
+
+void qga_debug_internal(const char *funcname, const char *fmt, ...) G_GNUC_PRINTF(2, 3);
+
+#define qga_debug(fmt, ...) qga_debug_internal(__func__, fmt, ## __VA_ARGS__)
+#define qga_debug_begin qga_debug("begin")
+#define qga_debug_end qga_debug("end")
+
+#endif

tests/unit/test-qga.c

@@ -665,6 +665,36 @@ static void test_qga_blockedrpcs(gconstpointer data)
     fixture_tear_down(&fix, NULL);
 }
 
+static void test_qga_allowedrpcs(gconstpointer data)
+{
+    TestFixture fix;
+    QDict *ret, *error;
+    const gchar *class, *desc;
+
+    fixture_setup(&fix, "-a guest-ping,guest-get-time", NULL);
+
+    /* check allowed RPCs */
+    ret = qmp_fd(fix.fd, "{'execute': 'guest-ping'}");
+    qmp_assert_no_error(ret);
+    qobject_unref(ret);
+
+    ret = qmp_fd(fix.fd, "{'execute': 'guest-get-time'}");
+    qmp_assert_no_error(ret);
+    qobject_unref(ret);
+
+    /* check something else */
+    ret = qmp_fd(fix.fd, "{'execute': 'guest-get-fsinfo'}");
+    g_assert_nonnull(ret);
+    error = qdict_get_qdict(ret, "error");
+    class = qdict_get_try_str(error, "class");
+    desc = qdict_get_try_str(error, "desc");
+    g_assert_cmpstr(class, ==, "CommandNotFound");
+    g_assert_nonnull(g_strstr_len(desc, -1, "has been disabled"));
+    qobject_unref(ret);
+
+    fixture_tear_down(&fix, NULL);
+}
+
 static void test_qga_config(gconstpointer data)
 {
     GError *error = NULL;
@@ -1090,6 +1120,7 @@ int main(int argc, char **argv)
                          test_qga_fsfreeze_status);
 
     g_test_add_data_func("/qga/blockedrpcs", NULL, test_qga_blockedrpcs);
+    g_test_add_data_func("/qga/allowedrpcs", NULL, test_qga_allowedrpcs);
     g_test_add_data_func("/qga/config", NULL, test_qga_config);
     g_test_add_data_func("/qga/guest-exec", &fix, test_qga_guest_exec);
     g_test_add_data_func("/qga/guest-exec-separated", &fix,