From mboxrd@z Thu Jan 1 00:00:00 1970
Return-Path: <io-uring-owner@kernel.org>
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 409B3CCA47C
for <io-uring@archiver.kernel.org>; Thu, 2 Jun 2022 09:04:28 +0000 (UTC)
Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand
id S232733AbiFBJE0 (ORCPT <rfc822;io-uring@archiver.kernel.org>);
Thu, 2 Jun 2022 05:04:26 -0400
Received: from lindbergh.monkeyblade.net ([23.128.96.19]:56728 "EHLO
lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org
with ESMTP id S232659AbiFBJEZ (ORCPT
<rfc822;io-uring@vger.kernel.org>); Thu, 2 Jun 2022 05:04:25 -0400
Received: from smtp-out2.suse.de (smtp-out2.suse.de [195.135.220.29])
by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 255E629567F;
Thu, 2 Jun 2022 02:04:24 -0700 (PDT)
Received: from relay2.suse.de (relay2.suse.de [149.44.160.134])
by smtp-out2.suse.de (Postfix) with ESMTP id D5D4D1F8C7;
Thu, 2 Jun 2022 09:04:22 +0000 (UTC)
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.cz; s=susede2_rsa;
t=1654160662; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc:
mime-version:mime-version:content-type:content-type:
in-reply-to:in-reply-to:references:references;
bh=JE43XyBt4F5UgiXwc28I6/EZJk5orkohdPvv7VBq3fc=;
b=1EygryP8IZBxvX5Dm8V9QrLjLSUC5warF6xeSo7WDFTpuDOLZtYse5K3UYInwH7Uji/Yk8
9/DU+l++DiAqxrL6UlAAXhKZEynEINg+In9DAGX91t/phB/gzj64O3OqVOx7olrxZlNZ1v
t8pvgkUqvkjKehd81PQGqWLsGS8nkYM=
DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=suse.cz;
s=susede2_ed25519; t=1654160662;
h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc:
mime-version:mime-version:content-type:content-type:
in-reply-to:in-reply-to:references:references;
bh=JE43XyBt4F5UgiXwc28I6/EZJk5orkohdPvv7VBq3fc=;
b=lqHGf8ktY+F61PtWn475PsO8oaOQmFYHWYtnt1vYxO0mTRqfhECY/wOP4uiefU8mzp/Bfq
6i1aw7cPWfQEnJDQ==
Received: from quack3.suse.cz (unknown [10.100.224.230])
(using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits))
(No client certificate requested)
by relay2.suse.de (Postfix) with ESMTPS id C14E52C141;
Thu, 2 Jun 2022 09:04:22 +0000 (UTC)
Received: by quack3.suse.cz (Postfix, from userid 1000)
id 76764A0633; Thu, 2 Jun 2022 11:04:22 +0200 (CEST)
Date: Thu, 2 Jun 2022 11:04:22 +0200
From: Jan Kara <jack@suse.cz>
To: Stefan Roesch <shr@fb.com>
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, hch@infradead.org,
axboe@kernel.dk, Christoph Hellwig <hch@lst.de>
Subject: Re: [PATCH v7 08/15] fs: add __remove_file_privs() with flags
parameter
Message-ID: <20220602090422.jkqou4ydyxxqiwsw@quack3.lan>
References: <20220601210141.3773402-1-shr@fb.com>
<20220601210141.3773402-9-shr@fb.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <20220601210141.3773402-9-shr@fb.com>
Precedence: bulk
List-ID: <io-uring.vger.kernel.org>
X-Mailing-List: io-uring@vger.kernel.org
On Wed 01-06-22 14:01:34, Stefan Roesch wrote:
> This adds the function __remove_file_privs, which allows the caller to
> pass the kiocb flags parameter.
>
> No intended functional changes in this patch.
>
> Signed-off-by: Stefan Roesch <shr@fb.com>
> Reviewed-by: Christoph Hellwig <hch@lst.de>
Looks good. Feel free to add:
Reviewed-by: Jan Kara <jack@suse.cz>
Honza
> ---
> fs/inode.c | 57 +++++++++++++++++++++++++++++++++++-------------------
> 1 file changed, 37 insertions(+), 20 deletions(-)
>
> diff --git a/fs/inode.c b/fs/inode.c
> index 9d9b422504d1..ac1cf5aa78c8 100644
> --- a/fs/inode.c
> +++ b/fs/inode.c
> @@ -2010,36 +2010,43 @@ 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 __file_remove_privs(struct file *file, unsigned int flags)
> {
> struct dentry *dentry = file_dentry(file);
> struct inode *inode = file_inode(file);
> + int error;
> int kill;
> - int error = 0;
>
> - /*
> - * Fast path for nothing security related.
> - * As well for non-regular files, e.g. blkdev inodes.
> - * For example, blkdev_write_iter() might get here
> - * trying to remove privs which it is not allowed to.
> - */
> if (IS_NOSEC(inode) || !S_ISREG(inode->i_mode))
> return 0;
>
> kill = dentry_needs_remove_privs(dentry);
> - if (kill < 0)
> + if (kill <= 0)
> return kill;
> - if (kill)
> - error = __remove_privs(file_mnt_user_ns(file), dentry, kill);
> +
> + if (flags & IOCB_NOWAIT)
> + return -EAGAIN;
> +
> + error = __remove_privs(file_mnt_user_ns(file), dentry, kill);
> if (!error)
> inode_has_no_xattr(inode);
>
> return error;
> }
> +
> +/**
> + * 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)
> +{
> + return __file_remove_privs(file, 0);
> +}
> EXPORT_SYMBOL(file_remove_privs);
>
> /**
> @@ -2090,18 +2097,28 @@ int file_update_time(struct file *file)
> }
> EXPORT_SYMBOL(file_update_time);
>
> -/* Caller must hold the file's inode lock */
> +/**
> + * file_modified - handle mandated vfs changes when modifying a file
> + * @file: file that 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_modified(struct file *file)
> {
> - int err;
> + int ret;
>
> /*
> * 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 = __file_remove_privs(file, 0);
> + if (ret)
> + return ret;
>
> if (unlikely(file->f_mode & FMODE_NOCMTIME))
> return 0;
> --
> 2.30.2
>
--
Jan Kara <jack@suse.com>
SUSE Labs, CR