From patchwork Mon Mar 14 17:55:32 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Darrick J. Wong" X-Patchwork-Id: 12780597 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 0B1D4C433F5 for ; Mon, 14 Mar 2022 17:55:36 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S243408AbiCNR4o (ORCPT ); Mon, 14 Mar 2022 13:56:44 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:53002 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S242402AbiCNR4n (ORCPT ); Mon, 14 Mar 2022 13:56:43 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id D31ED2DD62 for ; Mon, 14 Mar 2022 10:55:33 -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 7AB5160F5B for ; Mon, 14 Mar 2022 17:55:33 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id CD6C0C340EE; Mon, 14 Mar 2022 17:55:32 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1647280532; bh=TGenUJFFIkBdkUHG/YRUP2/veMp//Pd1G+6vNecFedI=; h=Date:From:To:Cc:Subject:From; b=Uc1iQz4ts/szW6F0RXVFoc6wTr2G0eR4NjFwr9n6T0ujrphAkA+MGYw7bWrcWeJdA 525aPT9LYZubHIn+9gxGI/Rn+hhmIqkFlatVOpI/q1L+jmXKMTOPhJ1kRHL8hsPRxG Y2CzLYYAZq8PwAKnS9elBBV8kIJcm5xBJzcAVwcwUQ7S4bexAPXO9Lao8KBxpmqOlw +H8WiZ03KAPrEDjP2hKzQ2u0wWuK5t6OAPbq6og5vDX2alXb2QyLyaZLPi4cXqslHm OQ21vwA4cKzMxsVP7PrDpDjxQF5LrHoZz72QZGk3tqjdXk5nL5rwdao4zVWAvYbxHX XuOIiCSCW85LA== Date: Mon, 14 Mar 2022 10:55:32 -0700 From: "Darrick J. Wong" To: Filipe Manana Cc: linux-btrfs@vger.kernel.org Subject: [PATCH v2] btrfs: fix fallocate to use file_modified to update permissions consistently Message-ID: <20220314175532.GB8165@magnolia> MIME-Version: 1.0 Content-Disposition: inline Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org From: Darrick J. Wong Since the initial introduction of (posix) fallocate back at the turn of the century, it has been possible to use this syscall to change the user-visible contents of files. This can happen by extending the file size during a preallocation, or through any of the newer modes (punch, zero range). Because the call can be used to change file contents, we should treat it like we do any other modification to a file -- update the mtime, and drop set[ug]id privileges/capabilities. The VFS function file_modified() does all this for us if pass it a locked inode, so let's make fallocate drop permissions correctly. Signed-off-by: Darrick J. Wong Reviewed-by: Filipe Manana --- v2: move up file_modified to catch a case where we could modify file contents but fail on something else before we end up calling file_modified --- fs/btrfs/file.c | 13 +++++++++++-- 1 file changed, 11 insertions(+), 2 deletions(-) diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c index a0179cc62913..28ddd9cf2069 100644 --- a/fs/btrfs/file.c +++ b/fs/btrfs/file.c @@ -2918,8 +2918,9 @@ int btrfs_replace_file_extents(struct btrfs_inode *inode, return ret; } -static int btrfs_punch_hole(struct inode *inode, loff_t offset, loff_t len) +static int btrfs_punch_hole(struct file *file, loff_t offset, loff_t len) { + struct inode *inode = file_inode(file); struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb); struct btrfs_root *root = BTRFS_I(inode)->root; struct extent_state *cached_state = NULL; @@ -2951,6 +2952,10 @@ static int btrfs_punch_hole(struct inode *inode, loff_t offset, loff_t len) goto out_only_mutex; } + ret = file_modified(file); + if (ret) + goto out_only_mutex; + lockstart = round_up(offset, btrfs_inode_sectorsize(BTRFS_I(inode))); lockend = round_down(offset + len, btrfs_inode_sectorsize(BTRFS_I(inode))) - 1; @@ -3391,7 +3396,7 @@ static long btrfs_fallocate(struct file *file, int mode, return -EOPNOTSUPP; if (mode & FALLOC_FL_PUNCH_HOLE) - return btrfs_punch_hole(inode, offset, len); + return btrfs_punch_hole(file, offset, len); /* * Only trigger disk allocation, don't trigger qgroup reserve @@ -3413,6 +3418,10 @@ static long btrfs_fallocate(struct file *file, int mode, goto out; } + ret = file_modified(file); + if (ret) + goto out; + /* * TODO: Move these two operations after we have checked * accurate reserved space, or fallocate can still fail but