From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-13.3 required=3.0 tests=BAYES_00,DKIMWL_WL_MED, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_IN_DEF_DKIM_WL autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 0F0C4C282C7 for ; Tue, 19 Jan 2021 18:29:34 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id DDF7F22CAD for ; Tue, 19 Jan 2021 18:29:33 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2388061AbhASRt7 (ORCPT ); Tue, 19 Jan 2021 12:49:59 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:60740 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2390044AbhASPG5 (ORCPT ); Tue, 19 Jan 2021 10:06:57 -0500 Received: from mail-lf1-x133.google.com (mail-lf1-x133.google.com [IPv6:2a00:1450:4864:20::133]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id E3293C061757 for ; Tue, 19 Jan 2021 07:05:28 -0800 (PST) Received: by mail-lf1-x133.google.com with SMTP id h205so29460755lfd.5 for ; Tue, 19 Jan 2021 07:05:28 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=gOmgvCPsNvi85/TpBsHHlznh/AXeaDwbv8LGPCZK7GU=; b=jHOv7ZfcUJDyBrUH8oJXnGIi8zR/GVQigV9JsU3VOD2zVPzE8Qi8FcxCv3RN2B9A6r xugkjyegXRk25clhQPkHPl6Bgq5is0HjaMKTdere1dxwfXiSoujavM6bCqwMy7DZTLAY XzwyrYIOx+UbZ4taCEFKeVgvzFkPqWMiBrHN0cesc58X2THa+V2gdhqFGvQ0m5hl69PP 86p4cNSHXci62Q5bRCDCUjqJlCKurpnZ2KQ8/bUtutXFEHhOZcuBiBOGHUyG7S3P/OJ0 UhrskVG5YmmxTBCZMbabr3ZIzMkK81tYRiWGV1k3KMjBXOmM5Zrq6ssCUVgGucgyhjVM mc6A== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=gOmgvCPsNvi85/TpBsHHlznh/AXeaDwbv8LGPCZK7GU=; b=VrhY+nivybB68E04pQeCCisJZce96qOcHfORrOZgUo9WckIWUrPbZ68Nlks3ZFsoNF F8WZAZCYk++VObp2dMDpei+LcXJHKZQdM3X0B/JIwiEXUIa59HYQgtUmassKha23ZoX8 G97iEDSMZZ78rnp0eDGwELXUp2eUDCVs+w65ZZg/83hIntzTpPcH43hXyCdEBREh9ByL LArutq+D8gvu87ZeSWzJQfmIB2CDUy2Y0569L6Xainh3STKe1Tcsh3QselQctJKAnASf QrYWw0qB6+3NYc1yyGfzxf0kRyT1h398UQ3qotvRLjS14JkXeqK+G6Tab3ZuAWk4Vgkh PkVw== X-Gm-Message-State: AOAM531OguhPZaFjsbVrazJm5DX0/FTB4CGkhoitCldz4nbofAEIEXD/ Rq9sXAQvQSwOoEKeqGAyEBQrvjmPUVceCm+3/ePvRw== X-Google-Smtp-Source: ABdhPJxFxS+hG4x6TwLiOwPtHwa+9Zao0MvjeAr8yET1CRB9c/HolYwSYvtkLR07E5CI/h61T92ZT6GwaxlT4i6ykfk= X-Received: by 2002:a19:197:: with SMTP id 145mr2043470lfb.352.1611068727150; Tue, 19 Jan 2021 07:05:27 -0800 (PST) MIME-Version: 1.0 References: <20210112220124.837960-1-christian.brauner@ubuntu.com> <20210112220124.837960-16-christian.brauner@ubuntu.com> In-Reply-To: <20210112220124.837960-16-christian.brauner@ubuntu.com> From: Jann Horn Date: Tue, 19 Jan 2021 16:05:00 +0100 Message-ID: Subject: Re: [PATCH v5 15/42] fs: add file_user_ns() helper To: Christian Brauner Cc: Alexander Viro , Christoph Hellwig , linux-fsdevel , John Johansen , James Morris , Mimi Zohar , Dmitry Kasatkin , Stephen Smalley , Casey Schaufler , Arnd Bergmann , Andreas Dilger , OGAWA Hirofumi , Geoffrey Thomas , Mrunal Patel , Josh Triplett , Andy Lutomirski , Theodore Tso , Alban Crequy , Tycho Andersen , David Howells , James Bottomley , Seth Forshee , =?UTF-8?Q?St=C3=A9phane_Graber?= , Linus Torvalds , Aleksa Sarai , Lennart Poettering , "Eric W. Biederman" , Stephen Barber , Phil Estes , Serge Hallyn , Kees Cook , Todd Kjos , Paul Moore , Jonathan Corbet , Linux Containers , linux-security-module , Linux API , Ext4 Developers List , linux-xfs@vger.kernel.org, linux-integrity@vger.kernel.org, SElinux list , Christoph Hellwig Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-xfs@vger.kernel.org On Wed, Jan 13, 2021 at 1:52 AM Christian Brauner wrote: > Add a simple helper to retrieve the user namespace associated with the > vfsmount of a file. Christoph correctly points out that this makes > codepaths (e.g. ioctls) way easier to follow that would otherwise > dereference via mnt_user_ns(file->f_path.mnt). > > In order to make file_user_ns() static inline we'd need to include > mount.h in either file.h or fs.h which seems undesirable so let's simply > not force file_user_ns() to be inline. [...] > +struct user_namespace *file_user_ns(struct file *file) > +{ > + return mnt_user_ns(file->f_path.mnt); > +} That name is confusing to me, because when I think of "the userns of a file", it's file->f_cred->user_ns. There are a bunch of places that look at that, as you can see from grepping for "f_cred->user_ns". If you really want this to be a separate helper, can you maybe give it a clearer name? file_mnt_user_ns(), or something like that, idk.