qemu-ga: implement win32 guest-set-user-password

Use NetUserSetInfo() to set the user password.

This function is notoriously known to be problematic for users with EFS
encrypted files. But the alternative, NetUserChangePassword() requires
the old password. Nevertheless, The EFS file should be recovered by
changing back to the old password.
Signed-off-by: NMarc-André Lureau <marcandre.lureau@gmail.com>
Reviewed-by: NDaniel P. Berrange <berrange@redhat.com>
Signed-off-by: NMichael Roth <mdroth@linux.vnet.ibm.com>

configure

@@ -732,7 +732,7 @@ if test "$mingw32" = "yes" ; then
   sysconfdir="\${prefix}"
   local_statedir=
   confsuffix=""
-  libs_qga="-lws2_32 -lwinmm -lpowrprof -liphlpapi $libs_qga"
+  libs_qga="-lws2_32 -lwinmm -lpowrprof -liphlpapi -lnetapi32 $libs_qga"
 fi
 
 werror=""

qga/commands-win32.c

@@ -26,6 +26,8 @@
 #include <setupapi.h>
 #include <initguid.h>
 #endif
+#include <lm.h>
+
 #include "qga/guest-agent-core.h"
 #include "qga/vss-win32.h"
 #include "qga-qmp-commands.h"
@@ -1192,12 +1194,84 @@ int64_t qmp_guest_set_vcpus(GuestLogicalProcessorList *vcpus, Error **errp)
     return -1;
 }
 
+static gchar *
+get_net_error_message(gint error)
+{
+    HMODULE module = NULL;
+    gchar *retval = NULL;
+    wchar_t *msg = NULL;
+    int flags, nchars;
+
+    flags = FORMAT_MESSAGE_ALLOCATE_BUFFER
+        |FORMAT_MESSAGE_IGNORE_INSERTS
+        |FORMAT_MESSAGE_FROM_SYSTEM;
+
+    if (error >= NERR_BASE && error <= MAX_NERR) {
+        module = LoadLibraryExW(L"netmsg.dll", NULL, LOAD_LIBRARY_AS_DATAFILE);
+
+        if (module != NULL) {
+            flags |= FORMAT_MESSAGE_FROM_HMODULE;
+        }
+    }
+
+    FormatMessageW(flags, module, error, 0, (LPWSTR)&msg, 0, NULL);
+
+    if (msg != NULL) {
+        nchars = wcslen(msg);
+
+        if (nchars > 2 && msg[nchars-1] == '\n' && msg[nchars-2] == '\r') {
+            msg[nchars-2] = '\0';
+        }
+
+        retval = g_utf16_to_utf8(msg, -1, NULL, NULL, NULL);
+
+        LocalFree(msg);
+    }
+
+    if (module != NULL) {
+        FreeLibrary(module);
+    }
+
+    return retval;
+}
+
 void qmp_guest_set_user_password(const char *username,
                                  const char *password,
                                  bool crypted,
                                  Error **errp)
 {
-    error_setg(errp, QERR_UNSUPPORTED);
+    NET_API_STATUS nas;
+    char *rawpasswddata = NULL;
+    size_t rawpasswdlen;
+    wchar_t *user, *wpass;
+    USER_INFO_1003 pi1003 = { 0, };
+
+    if (crypted) {
+        error_setg(errp, QERR_UNSUPPORTED);
+        return;
+    }
+
+    rawpasswddata = (char *)g_base64_decode(password, &rawpasswdlen);
+    rawpasswddata = g_renew(char, rawpasswddata, rawpasswdlen + 1);
+    rawpasswddata[rawpasswdlen] = '\0';
+
+    user = g_utf8_to_utf16(username, -1, NULL, NULL, NULL);
+    wpass = g_utf8_to_utf16(rawpasswddata, -1, NULL, NULL, NULL);
+
+    pi1003.usri1003_password = wpass;
+    nas = NetUserSetInfo(NULL, user,
+                         1003, (LPBYTE)&pi1003,
+                         NULL);
+
+    if (nas != NERR_Success) {
+        gchar *msg = get_net_error_message(nas);
+        error_setg(errp, "failed to set password: %s", msg);
+        g_free(msg);
+    }
+
+    g_free(user);
+    g_free(wpass);
+    g_free(rawpasswddata);
 }
 
 GuestMemoryBlockList *qmp_guest_get_memory_blocks(Error **errp)
@@ -1225,7 +1299,6 @@ GList *ga_command_blacklist_init(GList *blacklist)
     const char *list_unsupported[] = {
         "guest-suspend-hybrid",
         "guest-get-vcpus", "guest-set-vcpus",
-        "guest-set-user-password",
         "guest-get-memory-blocks", "guest-set-memory-blocks",
         "guest-get-memory-block-size",
         "guest-fsfreeze-freeze-list",