From patchwork Fri Feb 14 18:35:41 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Christian Brauner X-Patchwork-Id: 11383021 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id E6A5C1820 for ; Fri, 14 Feb 2020 18:38:25 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id C44242465D for ; Fri, 14 Feb 2020 18:38:25 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730798AbgBNSiL (ORCPT ); Fri, 14 Feb 2020 13:38:11 -0500 Received: from youngberry.canonical.com ([91.189.89.112]:33734 "EHLO youngberry.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730561AbgBNSiK (ORCPT ); Fri, 14 Feb 2020 13:38:10 -0500 Received: from ip5f5bf7ec.dynamic.kabel-deutschland.de ([95.91.247.236] helo=wittgenstein.fritz.box) by youngberry.canonical.com with esmtpsa (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.86_2) (envelope-from ) id 1j2fqZ-0000uO-2n; Fri, 14 Feb 2020 18:37:51 +0000 From: Christian Brauner To: =?utf-8?q?St=C3=A9phane_Graber?= , "Eric W. Biederman" , Aleksa Sarai , Jann Horn Cc: smbarber@chromium.org, Seth Forshee , Alexander Viro , Alexey Dobriyan , Serge Hallyn , James Morris , Kees Cook , Jonathan Corbet , Phil Estes , linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, containers@lists.linux-foundation.org, linux-security-module@vger.kernel.org, linux-api@vger.kernel.org, Christian Brauner Subject: [PATCH v2 15/28] fs: add is_userns_visible() helper Date: Fri, 14 Feb 2020 19:35:41 +0100 Message-Id: <20200214183554.1133805-16-christian.brauner@ubuntu.com> X-Mailer: git-send-email 2.25.0 In-Reply-To: <20200214183554.1133805-1-christian.brauner@ubuntu.com> References: <20200214183554.1133805-1-christian.brauner@ubuntu.com> MIME-Version: 1.0 Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org Introduce a helper which makes it possible to detect fileystems whose superblock is visible in multiple user namespace. This currently only means proc and sys. Such filesystems usually have special semantics so their behavior will not be changed with the introduction of fsid mappings. Signed-off-by: Christian Brauner --- /* v2 */ unchanged --- include/linux/fs.h | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/include/linux/fs.h b/include/linux/fs.h index 3cd4fe6b845e..fdc8fb2d786b 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -3651,4 +3651,9 @@ static inline int inode_drain_writes(struct inode *inode) return filemap_write_and_wait(inode->i_mapping); } +static inline bool is_userns_visible(unsigned long iflags) +{ + return (iflags & SB_I_USERNS_VISIBLE); +} + #endif /* _LINUX_FS_H */