Code: copy_move_file (CopyMoveJob   *copy_job,
                GFile         *src,
                GFile         *dest_dir,
                gboolean       same_fs,
                gboolean       unique_names,
                char         **dest_fs_type,
                SourceInfo    *source_info,
                TransferInfo  *transfer_info,
                GHashTable    *debuting_files,
                GdkPoint      *position,
                gboolean       overwrite,
                gboolean      *skipped_file,
                gboolean       readonly_source_fs)
{
    GFile *dest, *new_dest;
    g_autofree gchar *dest_uri = NULL;
    GError *error;
    GFileCopyFlags flags;
    char *primary, *secondary, *details;
    int response;
    ProgressData pdata;
    gboolean would_recurse, is_merge;
    CommonJob *job;
    gboolean res;
    int unique_name_nr;
    gboolean handled_invalid_filename;

    job = (CommonJob *) copy_job;

    if (should_skip_file (job, src))
    {
        *skipped_file = TRUE;
        return;
    }

    unique_name_nr = 1;

    /* another file in the same directory might have handled the invalid
     * filename condition for us
     */
    handled_invalid_filename = *dest_fs_type != NULL;

    if (unique_names)
    {
        dest = get_unique_target_file (src, dest_dir, same_fs, *dest_fs_type, unique_name_nr++);
    }
    else if (copy_job->target_name != NULL)
    {
        dest = get_target_file_with_custom_name (src, dest_dir, *dest_fs_type, same_fs,
                                                 copy_job->target_name);
    }
    else
    {
        dest = get_target_file (src, dest_dir, *dest_fs_type, same_fs);
    }

    /* Don't allow recursive move/copy into itself.
     * (We would get a file system error if we proceeded but it is nicer to
     * detect and report it at this level) */
    if (test_dir_is_parent (dest_dir, src))
    {
        if (job->skip_all_error)
        {
            goto out;
        }

        /*  the run_warning() frees all strings passed in automatically  */
        primary = copy_job->is_move ? g_strdup (_("You cannot move a folder into itself."))
                  : g_strdup (_("You cannot copy a folder into itself."));
        secondary = g_strdup (_("The destination folder is inside the source folder."));

        response = run_cancel_or_skip_warning (job,
                                               primary,
                                               secondary,
                                               NULL,
                                               source_info->num_files,
                                               source_info->num_files - transfer_info->num_files);

        if (response == 0 || response == GTK_RESPONSE_DELETE_EVENT)
        {
            abort_job (job);
        }
        else if (response == 1)             /* skip all */
        {
            job->skip_all_error = TRUE;
        }
        else if (response == 2)             /* skip */
        {               /* do nothing */
        }
        else
        {
            g_assert_not_reached ();
        }

        goto out;
    }

    /* Don't allow copying over the source or one of the parents of the source.
     */
    if (test_dir_is_parent (src, dest))
    {
        if (job->skip_all_error)
        {
            goto out;
        }

        /*  the run_warning() frees all strings passed in automatically  */
        primary = copy_job->is_move ? g_strdup (_("You cannot move a file over itself."))
                  : g_strdup (_("You cannot copy a file over itself."));
        secondary = g_strdup (_("The source file would be overwritten by the destination."));

        response = run_cancel_or_skip_warning (job,
                                               primary,
                                               secondary,
                                               NULL,
                                               source_info->num_files,
                                               source_info->num_files - transfer_info->num_files);

        if (response == 0 || response == GTK_RESPONSE_DELETE_EVENT)
        {
            abort_job (job);
        }
        else if (response == 1)             /* skip all */
        {
            job->skip_all_error = TRUE;
        }
        else if (response == 2)             /* skip */
        {               /* do nothing */
        }
        else
        {
            g_assert_not_reached ();
        }

        goto out;
    }


retry:

    error = NULL;
    flags = G_FILE_COPY_NOFOLLOW_SYMLINKS;
    if (overwrite)
    {
        flags |= G_FILE_COPY_OVERWRITE;
    }
    if (readonly_source_fs)
    {
        flags |= G_FILE_COPY_TARGET_DEFAULT_PERMS;
    }

    pdata.job = copy_job;
    pdata.last_size = 0;
    pdata.source_info = source_info;
    pdata.transfer_info = transfer_info;

    if (copy_job->is_move)
    {
        res = g_file_move (src, dest,
                           flags,
                           job->cancellable,
                           copy_file_progress_callback,
                           &pdata,
                           &error);
    }
    else
    {
        res = g_file_copy (src, dest,
                           flags,
                           job->cancellable,
                           copy_file_progress_callback,
                           &pdata,
                           &error);
    }

    if (res)
    {
        GFile *real;

        real = map_possibly_volatile_file_to_real (dest, job->cancellable, &error);
        if (real == NULL)
        {
            res = FALSE;
        }
        else
        {
            g_object_unref (dest);
            dest = real;
        }
    }

    if (res)
    {
        transfer_info->num_files++;
        report_copy_progress (copy_job, source_info, transfer_info);

        if (debuting_files)
        {
            dest_uri = g_file_get_uri (dest);
            if (position)
            {
                nautilus_file_changes_queue_schedule_position_set (dest, *position, job->screen_num);
            }
            else if (eel_uri_is_desktop (dest_uri))
            {
                nautilus_file_changes_queue_schedule_position_remove (dest);
            }

            g_hash_table_replace (debuting_files, g_object_ref (dest), GINT_TO_POINTER (TRUE));
        }
        if (copy_job->is_move)
        {
            nautilus_file_changes_queue_file_moved (src, dest);
        }
        else
        {
            nautilus_file_changes_queue_file_added (dest);
        }

        /* If copying a trusted desktop file to the desktop,
         *  mark it as trusted. */
        if (copy_job->desktop_location != NULL &&
             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);
         }
 
         if (job->undo_info != NULL)
        {
            nautilus_file_undo_info_ext_add_origin_target_pair (NAUTILUS_FILE_UNDO_INFO_EXT (job->undo_info),
                                                                src, dest);
        }

        g_object_unref (dest);
        return;
    }

    if (!handled_invalid_filename &&
        IS_IO_ERROR (error, INVALID_FILENAME))
    {
        handled_invalid_filename = TRUE;

        g_assert (*dest_fs_type == NULL);
        *dest_fs_type = query_fs_type (dest_dir, job->cancellable);

        if (unique_names)
        {
            new_dest = get_unique_target_file (src, dest_dir, same_fs, *dest_fs_type, unique_name_nr);
        }
        else
        {
            new_dest = get_target_file (src, dest_dir, *dest_fs_type, same_fs);
        }

        if (!g_file_equal (dest, new_dest))
        {
            g_object_unref (dest);
            dest = new_dest;

            g_error_free (error);
            goto retry;
        }
        else
        {
            g_object_unref (new_dest);
        }
    }

    /* Conflict */
    if (!overwrite &&
        IS_IO_ERROR (error, EXISTS))
    {
        gboolean is_merge;
        FileConflictResponse *response;

        g_error_free (error);

        if (unique_names)
        {
            g_object_unref (dest);
            dest = get_unique_target_file (src, dest_dir, same_fs, *dest_fs_type, unique_name_nr++);
            goto retry;
        }

        is_merge = FALSE;

        if (is_dir (dest) && is_dir (src))
        {
            is_merge = TRUE;
        }

        if ((is_merge && job->merge_all) ||
            (!is_merge && job->replace_all))
        {
            overwrite = TRUE;
            goto retry;
        }

        if (job->skip_all_conflict)
        {
            goto out;
        }

        response = handle_copy_move_conflict (job, src, dest, dest_dir);

        if (response->id == GTK_RESPONSE_CANCEL ||
            response->id == GTK_RESPONSE_DELETE_EVENT)
        {
            file_conflict_response_free (response);
            abort_job (job);
        }
        else if (response->id == CONFLICT_RESPONSE_SKIP)
        {
            if (response->apply_to_all)
            {
                job->skip_all_conflict = TRUE;
            }
            file_conflict_response_free (response);
        }
        else if (response->id == CONFLICT_RESPONSE_REPLACE)             /* merge/replace */
        {
            if (response->apply_to_all)
            {
                if (is_merge)
                {
                    job->merge_all = TRUE;
                }
                else
                {
                    job->replace_all = TRUE;
                }
            }
            overwrite = TRUE;
            file_conflict_response_free (response);
            goto retry;
        }
        else if (response->id == CONFLICT_RESPONSE_RENAME)
        {
            g_object_unref (dest);
            dest = get_target_file_for_display_name (dest_dir,
                                                     response->new_name);
            file_conflict_response_free (response);
            goto retry;
        }
        else
        {
            g_assert_not_reached ();
        }
    }
    else if (overwrite &&
             IS_IO_ERROR (error, IS_DIRECTORY))
    {
        gboolean existing_file_deleted;
        DeleteExistingFileData data;

        g_error_free (error);

        data.job = job;
        data.source = src;

        existing_file_deleted =
            delete_file_recursively (dest,
                                     job->cancellable,
                                     existing_file_removed_callback,
                                     &data);

        if (existing_file_deleted)
        {
            goto retry;
        }
    }
    /* Needs to recurse */
    else if (IS_IO_ERROR (error, WOULD_RECURSE) ||
             IS_IO_ERROR (error, WOULD_MERGE))
    {
        is_merge = error->code == G_IO_ERROR_WOULD_MERGE;
        would_recurse = error->code == G_IO_ERROR_WOULD_RECURSE;
        g_error_free (error);

        if (overwrite && would_recurse)
        {
            error = NULL;

            /* Copying a dir onto file, first remove the file */
            if (!g_file_delete (dest, job->cancellable, &error) &&
                !IS_IO_ERROR (error, NOT_FOUND))
            {
                if (job->skip_all_error)
                {
                    g_error_free (error);
                    goto out;
                }
                if (copy_job->is_move)
                {
                    primary = f (_("Error while moving “%B”."), src);
                }
                else
                {
                    primary = f (_("Error while copying “%B”."), src);
                }
                secondary = f (_("Could not remove the already existing file with the same name in %F."), dest_dir);
                details = error->message;

                /* setting TRUE on show_all here, as we could have
                 * another error on the same file later.
                 */
                response = run_warning (job,
                                        primary,
                                        secondary,
                                        details,
                                        TRUE,
                                        CANCEL, SKIP_ALL, SKIP,
                                        NULL);

                g_error_free (error);

                if (response == 0 || response == GTK_RESPONSE_DELETE_EVENT)
                {
                    abort_job (job);
                }
                else if (response == 1)                     /* skip all */
                {
                    job->skip_all_error = TRUE;
                }
                else if (response == 2)                     /* skip */
                {                       /* do nothing */
                }
                else
                {
                    g_assert_not_reached ();
                }
                goto out;
            }
            if (error)
            {
                g_error_free (error);
                error = NULL;
            }
            nautilus_file_changes_queue_file_removed (dest);
        }

        if (is_merge)
        {
            /* On merge we now write in the target directory, which may not
             *   be in the same directory as the source, even if the parent is
             *   (if the merged directory is a mountpoint). This could cause
             *   problems as we then don't transcode filenames.
             *   We just set same_fs to FALSE which is safe but a bit slower. */
            same_fs = FALSE;
        }

        if (!copy_move_directory (copy_job, src, &dest, same_fs,
                                  would_recurse, dest_fs_type,
                                  source_info, transfer_info,
                                  debuting_files, skipped_file,
                                  readonly_source_fs))
        {
            /* destination changed, since it was an invalid file name */
            g_assert (*dest_fs_type != NULL);
            handled_invalid_filename = TRUE;
            goto retry;
        }

        g_object_unref (dest);
        return;
    }
    else if (IS_IO_ERROR (error, CANCELLED))
    {
        g_error_free (error);
    }
    /* Other error */
    else
    {
        if (job->skip_all_error)
        {
            g_error_free (error);
            goto out;
        }
        primary = f (_("Error while copying “%B”."), src);
        secondary = f (_("There was an error copying the file into %F."), dest_dir);
        details = error->message;

        response = run_cancel_or_skip_warning (job,
                                               primary,
                                               secondary,
                                               details,
                                               source_info->num_files,
                                               source_info->num_files - transfer_info->num_files);

        g_error_free (error);

        if (response == 0 || response == GTK_RESPONSE_DELETE_EVENT)
        {
            abort_job (job);
        }
        else if (response == 1)             /* skip all */
        {
            job->skip_all_error = TRUE;
        }
        else if (response == 2)             /* skip */
        {               /* do nothing */
        }
        else
        {
            g_assert_not_reached ();
        }
    }
out:
    *skipped_file = TRUE;     /* Or aborted, but same-same */
    g_object_unref (dest);
}

Vulnerability Type: Exec Code 
CWE ID: CWE-20
Summary: GNOME Nautilus before 3.23.90 allows attackers to spoof a file type by using the .desktop file extension, as demonstrated by an attack in which a .desktop file's Name field ends in .pdf but this file's Exec field launches a malicious *sh -c* command. In other words, Nautilus provides no UI indication that a file actually has the potentially unsafe .desktop extension; instead, the UI only shows the .pdf extension. One (slightly) mitigating factor is that an attack requires the .desktop file to have execute permission. The solution is to ask the user to confirm that the file is supposed to be treated as a .desktop file, and then remember the user's answer in the metadata::trusted field.
Commit Message: 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