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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 21D5EC4332F for ; Tue, 17 May 2022 13:18:55 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1347449AbiEQNSw (ORCPT ); Tue, 17 May 2022 09:18:52 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:50958 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S239044AbiEQNSt (ORCPT ); Tue, 17 May 2022 09:18:49 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 4A7AE41F94; Tue, 17 May 2022 06:18:48 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 9ED3C614A4; Tue, 17 May 2022 13:18:47 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id EAFEAC385B8; Tue, 17 May 2022 13:18:44 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1652793527; bh=/EUREbTS3LyoHsYjut8bYc/O9ZMXv63PeDjg8xMEuoM=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=t9zTth6EOx2/k9M4nc62KO2zsWg10ZVl4Tv5nxeCiZbc6X0dtiYYn+9mg7xJ9upxO vXs6OYI5PRVbN/lUhNfYTlckpoGQUTWME8hU0+sIGR5uwIGuY0XP6jU6WFBZYvV0+T ZXMXB4kuub6Jw0CRT5Hobwvws0w7tjmCxcjH8pek+YZUAawc0WXh91McyOnOyWoVyF qMFnyMti61cz5xCupTfJs8guc3e6J09B2PWo6Dwi79R7EXoJ1tEahhWfx844HfWSdN 5S64GiG0cI/sRXYWRq/R5JVPYcNBzXZR/FLkdTPdF2nQiZnVSjWvrqHZnp9k+eLnDK O9+deqmWcMKDw== Date: Tue, 17 May 2022 15:18:41 +0200 From: Christian Brauner To: Stefan Roesch Cc: io-uring@vger.kernel.org, kernel-team@fb.com, linux-mm@kvack.org, linux-xfs@vger.kernel.org, linux-fsdevel@vger.kernel.org, david@fromorbit.com, jack@suse.cz Subject: Re: [RFC PATCH v2 06/16] fs: split off need_remove_file_privs() do_remove_file_privs() Message-ID: <20220517131841.wjuy7mmqo3w2rdsv@wittgenstein> References: <20220516164718.2419891-1-shr@fb.com> <20220516164718.2419891-7-shr@fb.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20220516164718.2419891-7-shr@fb.com> Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org On Mon, May 16, 2022 at 09:47:08AM -0700, Stefan Roesch wrote: > This splits off the function need_remove_file_privs() from the function > do_remove_file_privs() from the function file_remove_privs(). > > No intended functional changes in this patch. > > Signed-off-by: Stefan Roesch > --- Just a few nits... > fs/inode.c | 57 ++++++++++++++++++++++++++++++++++++------------------ > 1 file changed, 38 insertions(+), 19 deletions(-) > > diff --git a/fs/inode.c b/fs/inode.c > index 9d9b422504d1..a6d70a1983f8 100644 > --- a/fs/inode.c > +++ b/fs/inode.c > @@ -2010,17 +2010,8 @@ static int __remove_privs(struct user_namespace *mnt_userns, > return notify_change(mnt_userns, dentry, &newattrs, NULL); > } > > -/* > - * Remove special file priviledges (suid, capabilities) when file is written > - * to or truncated. > - */ > -int file_remove_privs(struct file *file) > +static int need_file_remove_privs(struct inode *inode, struct dentry *dentry) I'd rather call this file_needs_remove_privs()? > { > - struct dentry *dentry = file_dentry(file); > - struct inode *inode = file_inode(file); > - int kill; > - int error = 0; > - > /* > * Fast path for nothing security related. > * As well for non-regular files, e.g. blkdev inodes. > @@ -2030,16 +2021,37 @@ int file_remove_privs(struct file *file) > if (IS_NOSEC(inode) || !S_ISREG(inode->i_mode)) > return 0; > > - kill = dentry_needs_remove_privs(dentry); > - if (kill < 0) > - return kill; > - if (kill) > - error = __remove_privs(file_mnt_user_ns(file), dentry, kill); > + return dentry_needs_remove_privs(dentry); > +} > + > +static int do_file_remove_privs(struct file *file, struct inode *inode, > + struct dentry *dentry, int kill) and that __file_remove_privs() which matches the rest of the file since here we don't have a lot of do_* but rather __* convention afaict. > +{ > + int error = 0; > + > + error = __remove_privs(file_mnt_user_ns(file), dentry, kill); > if (!error) > inode_has_no_xattr(inode); > > return error; > } > + > +/* > + * Remove special file privileges (suid, capabilities) when file is written > + * to or truncated. > + */ > +int file_remove_privs(struct file *file) This is a generic comment, not aimed specifically at your change but we really need to get better at kernel-doc... Since you're already touching this code could you at least to the exported function you're modifying add sm like: /** * file_remove_privs - remove special file privileges (suid, capabilities) * @file: file to remove privileges from * * When file is modified by a write or truncation ensure that special * file privileges are removed. * * Return: 0 on success, negative errno on failure. */ int file_remove_privs(struct file *file) This will then render on kernel.org/doc see e.g. lookup_one(): https://www.kernel.org/doc/html/latest/filesystems/api-summary.html?highlight=lookup_one#c.lookup_one > +{ > + struct dentry *dentry = file_dentry(file); > + struct inode *inode = file_inode(file); > + int kill; > + > + kill = need_file_remove_privs(inode, dentry); > + if (kill <= 0) > + return kill; > + > + return do_file_remove_privs(file, inode, dentry, kill); > +} > EXPORT_SYMBOL(file_remove_privs); > > /** > @@ -2093,15 +2105,22 @@ EXPORT_SYMBOL(file_update_time); > /* Caller must hold the file's inode lock */ > int file_modified(struct file *file) Similar I'd add sm like: /** * file_modified - handle mandated vfs changes when modifying a file * @file: file that was was modified * * When file has been modified ensure that special * file privileges are removed and time settings are updated. * * Context: Caller must hold the file's inode lock. * * Return: 0 on success, negative errno on failure. */ int file_remove_privs(struct file *file) > { > - int err; > + int ret; > + struct dentry *dentry = file_dentry(file); > + struct inode *inode = file_inode(file); > > /* > * Clear the security bits if the process is not being run by root. > * This keeps people from modifying setuid and setgid binaries. > */ > - err = file_remove_privs(file); > - if (err) > - return err; > + ret = need_file_remove_privs(inode, dentry); > + if (ret < 0) { > + return ret; > + } else if (ret > 0) { > + ret = do_file_remove_privs(file, inode, dentry, ret); > + if (ret) > + return ret; > + } The else-if branch looks a bit unorthodox to me. I'd probably rather make this: ret = need_file_remove_privs(inode, dentry); if (ret < 0) return ret; if (ret > 0) { ret = do_file_remove_privs(file, inode, dentry, ret); if (ret) return ret; } > > if (unlikely(file->f_mode & FMODE_NOCMTIME)) > return 0; > -- > 2.30.2 >