[nautilus] mime-actions: use file metadata for trusting desktop files



commit 1630f53481f445ada0a455e9979236d31a8d3bb0
Author: Carlos Soriano <csoriano gnome org>
Date:   Mon Feb 6 18:47:54 2017 +0100

    mime-actions: use file metadata for trusting desktop files
    
    Currently we only trust desktop files that have the executable bit
    set, and don't replace the displayed icon or the displayed name until
    it's trusted, which prevents for running random programs by a malicious
    desktop file.
    
    However, the executable permission is preserved if the desktop file
    comes from a compressed file.
    
    To prevent this, add a metadata::trusted metadata to the file once the
    user acknowledges the file as trusted. This adds metadata to the file,
    which cannot be added unless it has access to the computer.
    
    Also remove the SHEBANG "trusted" content we were putting inside the
    desktop file, since that doesn't add more security since it can come
    with the file itself.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=777991

 src/nautilus-directory-async.c |    7 ++-
 src/nautilus-file-operations.c |  153 ++++++++--------------------------------
 src/nautilus-file-operations.h |   10 ++--
 src/nautilus-metadata.c        |    1 +
 src/nautilus-metadata.h        |    2 +
 src/nautilus-mime-actions.c    |   46 +++++++-----
 6 files changed, 73 insertions(+), 146 deletions(-)
---
diff --git a/src/nautilus-directory-async.c b/src/nautilus-directory-async.c
index e8a10cd..b02e3de 100644
--- a/src/nautilus-directory-async.c
+++ b/src/nautilus-directory-async.c
@@ -30,6 +30,7 @@
 #include "nautilus-global-preferences.h"
 #include "nautilus-link.h"
 #include "nautilus-profile.h"
+#include "nautilus-metadata.h"
 #include <eel/eel-glib-extensions.h>
 #include <gtk/gtk.h>
 #include <libxml/parser.h>
@@ -3580,13 +3581,17 @@ is_link_trusted (NautilusFile *file,
 {
     GFile *location;
     gboolean res;
+    g_autofree gchar* trusted = NULL;
 
     if (!is_launcher)
     {
         return TRUE;
     }
 
-    if (nautilus_file_can_execute (file))
+    trusted = nautilus_file_get_metadata (file,
+                                          NAUTILUS_METADATA_KEY_DESKTOP_FILE_TRUSTED,
+                                          NULL);
+    if (nautilus_file_can_execute (file) && trusted != NULL)
     {
         return TRUE;
     }
diff --git a/src/nautilus-file-operations.c b/src/nautilus-file-operations.c
index 89bc93d..cd8ea0b 100644
--- a/src/nautilus-file-operations.c
+++ b/src/nautilus-file-operations.c
@@ -235,10 +235,10 @@ typedef struct
 #define COPY_FORCE _("Copy _Anyway")
 
 static void
-mark_desktop_file_trusted (CommonJob    *common,
-                           GCancellable *cancellable,
-                           GFile        *file,
-                           gboolean      interactive);
+mark_desktop_file_executable (CommonJob    *common,
+                              GCancellable *cancellable,
+                              GFile        *file,
+                              gboolean      interactive);
 
 static gboolean
 is_all_button_text (const char *button_text)
@@ -5290,10 +5290,10 @@ retry:
             g_file_equal (copy_job->desktop_location, dest_dir) &&
             is_trusted_desktop_file (src, job->cancellable))
         {
-            mark_desktop_file_trusted (job,
-                                       job->cancellable,
-                                       dest,
-                                       FALSE);
+            mark_desktop_file_executable (job,
+                                          job->cancellable,
+                                          dest,
+                                          FALSE);
         }
 
         if (job->undo_info != NULL)
@@ -7887,9 +7887,9 @@ nautilus_file_operations_empty_trash (GtkWidget *parent_view)
 }
 
 static void
-mark_trusted_task_done (GObject      *source_object,
-                        GAsyncResult *res,
-                        gpointer      user_data)
+mark_desktop_file_executable_task_done (GObject      *source_object,
+                                        GAsyncResult *res,
+                                        gpointer      user_data)
 {
     MarkTrustedJob *job = user_data;
 
@@ -7907,110 +7907,19 @@ mark_trusted_task_done (GObject      *source_object,
 #define TRUSTED_SHEBANG "#!/usr/bin/env xdg-open\n"
 
 static void
-mark_desktop_file_trusted (CommonJob    *common,
-                           GCancellable *cancellable,
-                           GFile        *file,
-                           gboolean      interactive)
+mark_desktop_file_executable (CommonJob    *common,
+                              GCancellable *cancellable,
+                              GFile        *file,
+                              gboolean      interactive)
 {
-    char *contents, *new_contents;
-    gsize length, new_length;
     GError *error;
     guint32 current_perms, new_perms;
     int response;
     GFileInfo *info;
 
 retry:
-    error = NULL;
-    if (!g_file_load_contents (file,
-                               cancellable,
-                               &contents, &length,
-                               NULL, &error))
-    {
-        if (interactive)
-        {
-            response = run_error (common,
-                                  g_strdup (_("Unable to mark launcher trusted (executable)")),
-                                  error->message,
-                                  NULL,
-                                  FALSE,
-                                  CANCEL, RETRY,
-                                  NULL);
-        }
-        else
-        {
-            response = 0;
-        }
-
-
-        if (response == 0 || response == GTK_RESPONSE_DELETE_EVENT)
-        {
-            abort_job (common);
-        }
-        else if (response == 1)
-        {
-            goto retry;
-        }
-        else
-        {
-            g_assert_not_reached ();
-        }
-
-        goto out;
-    }
-
-    if (!g_str_has_prefix (contents, "#!"))
-    {
-        new_length = length + strlen (TRUSTED_SHEBANG);
-        new_contents = g_malloc (new_length);
-
-        strcpy (new_contents, TRUSTED_SHEBANG);
-        memcpy (new_contents + strlen (TRUSTED_SHEBANG),
-                contents, length);
-
-        if (!g_file_replace_contents (file,
-                                      new_contents,
-                                      new_length,
-                                      NULL,
-                                      FALSE, 0,
-                                      NULL, cancellable, &error))
-        {
-            g_free (contents);
-            g_free (new_contents);
-
-            if (interactive)
-            {
-                response = run_error (common,
-                                      g_strdup (_("Unable to mark launcher trusted (executable)")),
-                                      error->message,
-                                      NULL,
-                                      FALSE,
-                                      CANCEL, RETRY,
-                                      NULL);
-            }
-            else
-            {
-                response = 0;
-            }
-
-            if (response == 0 || response == GTK_RESPONSE_DELETE_EVENT)
-            {
-                abort_job (common);
-            }
-            else if (response == 1)
-            {
-                goto retry;
-            }
-            else
-            {
-                g_assert_not_reached ();
-            }
-
-            goto out;
-        }
-        g_free (new_contents);
-    }
-    g_free (contents);
 
+    error = NULL;
     info = g_file_query_info (file,
                               G_FILE_ATTRIBUTE_STANDARD_TYPE ","
                               G_FILE_ATTRIBUTE_UNIX_MODE,
@@ -8101,10 +8010,10 @@ out:
 }
 
 static void
-mark_trusted_task_thread_func (GTask        *task,
-                               gpointer      source_object,
-                               gpointer      task_data,
-                               GCancellable *cancellable)
+mark_desktop_file_executable_task_thread_func (GTask        *task,
+                                               gpointer      source_object,
+                                               gpointer      task_data,
+                                               GCancellable *cancellable)
 {
     MarkTrustedJob *job = task_data;
     CommonJob *common;
@@ -8113,18 +8022,18 @@ mark_trusted_task_thread_func (GTask        *task,
 
     nautilus_progress_info_start (job->common.progress);
 
-    mark_desktop_file_trusted (common,
-                               cancellable,
-                               job->file,
-                               job->interactive);
+    mark_desktop_file_executable (common,
+                                  cancellable,
+                                  job->file,
+                                  job->interactive);
 }
 
 void
-nautilus_file_mark_desktop_file_trusted (GFile              *file,
-                                         GtkWindow          *parent_window,
-                                         gboolean            interactive,
-                                         NautilusOpCallback  done_callback,
-                                         gpointer            done_callback_data)
+nautilus_file_mark_desktop_file_executable (GFile              *file,
+                                            GtkWindow          *parent_window,
+                                            gboolean            interactive,
+                                            NautilusOpCallback  done_callback,
+                                            gpointer            done_callback_data)
 {
     GTask *task;
     MarkTrustedJob *job;
@@ -8135,9 +8044,9 @@ nautilus_file_mark_desktop_file_trusted (GFile              *file,
     job->done_callback = done_callback;
     job->done_callback_data = done_callback_data;
 
-    task = g_task_new (NULL, NULL, mark_trusted_task_done, job);
+    task = g_task_new (NULL, NULL, mark_desktop_file_executable_task_done, job);
     g_task_set_task_data (task, job, NULL);
-    g_task_run_in_thread (task, mark_trusted_task_thread_func);
+    g_task_run_in_thread (task, mark_desktop_file_executable_task_thread_func);
     g_object_unref (task);
 }
 
diff --git a/src/nautilus-file-operations.h b/src/nautilus-file-operations.h
index 31b782d..a479ee6 100644
--- a/src/nautilus-file-operations.h
+++ b/src/nautilus-file-operations.h
@@ -146,11 +146,11 @@ void nautilus_file_operations_link      (GList                *files,
                                         GtkWindow            *parent_window,
                                         NautilusCopyCallback  done_callback,
                                         gpointer              done_callback_data);
-void nautilus_file_mark_desktop_file_trusted (GFile           *file,
-                                             GtkWindow        *parent_window,
-                                             gboolean          interactive,
-                                             NautilusOpCallback done_callback,
-                                             gpointer          done_callback_data);
+void nautilus_file_mark_desktop_file_executable (GFile           *file,
+                                                 GtkWindow        *parent_window,
+                                                 gboolean          interactive,
+                                                 NautilusOpCallback done_callback,
+                                                 gpointer          done_callback_data);
 void nautilus_file_operations_extract_files (GList                   *files,
                                              GFile                   *destination_directory,
                                              GtkWindow               *parent_window,
diff --git a/src/nautilus-metadata.c b/src/nautilus-metadata.c
index 8316426..bee04e7 100644
--- a/src/nautilus-metadata.c
+++ b/src/nautilus-metadata.c
@@ -51,6 +51,7 @@ static char *used_metadata_names[] =
     NAUTILUS_METADATA_KEY_CUSTOM_ICON_NAME,
     NAUTILUS_METADATA_KEY_SCREEN,
     NAUTILUS_METADATA_KEY_EMBLEMS,
+    NAUTILUS_METADATA_KEY_DESKTOP_FILE_TRUSTED,
     NULL
 };
 
diff --git a/src/nautilus-metadata.h b/src/nautilus-metadata.h
index 7a734af..c4a303e 100644
--- a/src/nautilus-metadata.h
+++ b/src/nautilus-metadata.h
@@ -67,6 +67,8 @@
 #define NAUTILUS_METADATA_KEY_SCREEN                           "screen"
 #define NAUTILUS_METADATA_KEY_EMBLEMS                          "emblems"
 
+#define NAUTILUS_METADATA_KEY_DESKTOP_FILE_TRUSTED                             "trusted"
+
 guint nautilus_metadata_get_id (const char *metadata);
 
 #endif /* NAUTILUS_METADATA_H */
diff --git a/src/nautilus-mime-actions.c b/src/nautilus-mime-actions.c
index 036b967..14fe44b 100644
--- a/src/nautilus-mime-actions.c
+++ b/src/nautilus-mime-actions.c
@@ -42,6 +42,7 @@
 #include "nautilus-program-choosing.h"
 #include "nautilus-global-preferences.h"
 #include "nautilus-signaller.h"
+#include "nautilus-metadata.h"
 
 #define DEBUG_FLAG NAUTILUS_DEBUG_MIME
 #include "nautilus-debug.h"
@@ -221,7 +222,6 @@ struct
 #define RESPONSE_RUN 1000
 #define RESPONSE_DISPLAY 1001
 #define RESPONSE_RUN_IN_TERMINAL 1002
-#define RESPONSE_MARK_TRUSTED 1003
 
 #define SILENT_WINDOW_OPEN_LIMIT 5
 #define SILENT_OPEN_LIMIT 5
@@ -1517,24 +1517,35 @@ untrusted_launcher_response_callback (GtkDialog                 *dialog,
 
     switch (response_id)
     {
-        case RESPONSE_RUN:
+        case GTK_RESPONSE_OK:
         {
+            file = nautilus_file_get_location (parameters->file);
+
+            /* We need to do this in order to prevent malicious desktop files
+             * with the executable bit already set.
+             * See https://bugzilla.gnome.org/show_bug.cgi?id=777991
+             */
+            nautilus_file_set_metadata (parameters->file, NAUTILUS_METADATA_KEY_DESKTOP_FILE_TRUSTED,
+                                        NULL,
+                                        "yes");
+
+            nautilus_file_mark_desktop_file_executable (file,
+                                                        parameters->parent_window,
+                                                        TRUE,
+                                                        NULL, NULL);
+
+            /* Need to force a reload of the attributes so is_trusted is marked
+             * correctly. Not sure why the general monitor doesn't fire in this
+             * case when setting the metadata
+             */
+            nautilus_file_invalidate_all_attributes (parameters->file);
+
             screen = gtk_widget_get_screen (GTK_WIDGET (parameters->parent_window));
             uri = nautilus_file_get_uri (parameters->file);
             DEBUG ("Launching untrusted launcher %s", uri);
             nautilus_launch_desktop_file (screen, uri, NULL,
                                           parameters->parent_window);
             g_free (uri);
-        }
-        break;
-
-        case RESPONSE_MARK_TRUSTED:
-        {
-            file = nautilus_file_get_location (parameters->file);
-            nautilus_file_mark_desktop_file_trusted (file,
-                                                     parameters->parent_window,
-                                                     TRUE,
-                                                     NULL, NULL);
             g_object_unref (file);
         }
         break;
@@ -1590,17 +1601,16 @@ activate_desktop_file (ActivateParameters *parameters,
                       "text", primary,
                       "secondary-text", secondary,
                       NULL);
+
         gtk_dialog_add_button (GTK_DIALOG (dialog),
-                               _("_Launch Anyway"), RESPONSE_RUN);
+                               _("_Cancel"), GTK_RESPONSE_CANCEL);
+
+        gtk_dialog_set_default_response (GTK_DIALOG (dialog), GTK_RESPONSE_CANCEL);
         if (nautilus_file_can_set_permissions (file))
         {
             gtk_dialog_add_button (GTK_DIALOG (dialog),
-                                   _("Mark as _Trusted"), RESPONSE_MARK_TRUSTED);
+                                   _("Trust and _Launch"), GTK_RESPONSE_OK);
         }
-        gtk_dialog_add_button (GTK_DIALOG (dialog),
-                               _("_Cancel"), GTK_RESPONSE_CANCEL);
-        gtk_dialog_set_default_response (GTK_DIALOG (dialog), GTK_RESPONSE_CANCEL);
-
         g_signal_connect (dialog, "response",
                           G_CALLBACK (untrusted_launcher_response_callback),
                           parameters_desktop);


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