From patchwork Fri Jul 2 09:00:12 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Luis Henriques X-Patchwork-Id: 12355659 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=-15.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,UNPARSEABLE_RELAY, URIBL_BLOCKED autolearn=unavailable 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 AB053C11F6A for ; Fri, 2 Jul 2021 09:00:19 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 8D9BF613ED for ; Fri, 2 Jul 2021 09:00:19 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230526AbhGBJCt (ORCPT ); Fri, 2 Jul 2021 05:02:49 -0400 Received: from smtp-out2.suse.de ([195.135.220.29]:45108 "EHLO smtp-out2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230418AbhGBJCt (ORCPT ); Fri, 2 Jul 2021 05:02:49 -0400 Received: from imap.suse.de (imap-alt.suse-dmz.suse.de [192.168.254.47]) (using TLSv1.2 with cipher ECDHE-ECDSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp-out2.suse.de (Postfix) with ESMTPS id 555C62005F; Fri, 2 Jul 2021 09:00:16 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_rsa; t=1625216416; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version: content-transfer-encoding:content-transfer-encoding; bh=lXxrAJvjehNUyVTRE9GdwBU5ZEfgYvUxtPib1oNykLE=; b=GdgFi0iPRtWxSfXAzQXTiUd8/pjb3fo7fQICjK8ECg24L9R2Zg12NU49BKfhcW4SCELQhp idxnX1QAdSO10dFzTE7j4wX5iy85Q5LehEmje2GQFiyizq5hNQsDtUoF2XoObm1ydoZ88f kW0E+Qh5GZGcJd4hrwhVrzpjhK+PjfU= DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_ed25519; t=1625216416; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version: content-transfer-encoding:content-transfer-encoding; bh=lXxrAJvjehNUyVTRE9GdwBU5ZEfgYvUxtPib1oNykLE=; b=D520AvdHQXfz62vwi3FX/lUIKLeowI6KVmfDrXHheUFdFHyn/GTHKK/bw9dEtW7z7I342c l1Z5lDNNw4/pBKCQ== Received: from imap3-int (imap-alt.suse-dmz.suse.de [192.168.254.47]) by imap.suse.de (Postfix) with ESMTP id A33EE11CD6; Fri, 2 Jul 2021 09:00:15 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_rsa; t=1625216416; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version: content-transfer-encoding:content-transfer-encoding; bh=lXxrAJvjehNUyVTRE9GdwBU5ZEfgYvUxtPib1oNykLE=; b=GdgFi0iPRtWxSfXAzQXTiUd8/pjb3fo7fQICjK8ECg24L9R2Zg12NU49BKfhcW4SCELQhp idxnX1QAdSO10dFzTE7j4wX5iy85Q5LehEmje2GQFiyizq5hNQsDtUoF2XoObm1ydoZ88f kW0E+Qh5GZGcJd4hrwhVrzpjhK+PjfU= DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_ed25519; t=1625216416; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version: content-transfer-encoding:content-transfer-encoding; bh=lXxrAJvjehNUyVTRE9GdwBU5ZEfgYvUxtPib1oNykLE=; b=D520AvdHQXfz62vwi3FX/lUIKLeowI6KVmfDrXHheUFdFHyn/GTHKK/bw9dEtW7z7I342c l1Z5lDNNw4/pBKCQ== Received: from director2.suse.de ([192.168.254.72]) by imap3-int with ESMTPSA id BxYCJZ/V3mAVMgAALh3uQQ (envelope-from ); Fri, 02 Jul 2021 09:00:15 +0000 Received: from localhost (brahms [local]) by brahms (OpenSMTPD) with ESMTPA id 0c881fca; Fri, 2 Jul 2021 09:00:15 +0000 (UTC) From: Luis Henriques To: Alexander Viro Cc: linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, Luis Henriques , Nicolas Boichat , Amir Goldstein , Olga Kornievskaia , Petr Vorel , Steve French , Trond Myklebust , linux-nfs@vger.kernel.org, kernel test robot Subject: [PATCH v12] vfs: fix copy_file_range regression in cross-fs copies Date: Fri, 2 Jul 2021 10:00:12 +0100 Message-Id: <20210702090012.28458-1-lhenriques@suse.de> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org A regression has been reported by Nicolas Boichat, found while using the copy_file_range syscall to copy a tracefs file. Before commit 5dae222a5ff0 ("vfs: allow copy_file_range to copy across devices") the kernel would return -EXDEV to userspace when trying to copy a file across different filesystems. After this commit, the syscall doesn't fail anymore and instead returns zero (zero bytes copied), as this file's content is generated on-the-fly and thus reports a size of zero. This patch restores some cross-filesystem copy restrictions that existed prior to commit 5dae222a5ff0 ("vfs: allow copy_file_range to copy across devices"). Filesystems are still allowed to fall-back to the VFS generic_copy_file_range() implementation, but that has now to be done explicitly. The short-circuit code for the case where the copy length is zero has also been dropped from the VFS code. This is because a zero size copy between two files shall provide a clear indication on whether or not the filesystem supports non-zero copies. nfsd is also modified to fall-back into generic_copy_file_range() in case vfs_copy_file_range() fails with -EOPNOTSUPP or -EXDEV. Fixes: 5dae222a5ff0 ("vfs: allow copy_file_range to copy across devices") Link: https://lore.kernel.org/linux-fsdevel/20210212044405.4120619-1-drinkcat@chromium.org/ Link: https://lore.kernel.org/linux-fsdevel/CANMq1KDZuxir2LM5jOTm0xx+BnvW=ZmpsG47CyHFJwnw7zSX6Q@mail.gmail.com/ Link: https://lore.kernel.org/linux-fsdevel/20210126135012.1.If45b7cdc3ff707bc1efa17f5366057d60603c45f@changeid/ Link: https://lore.kernel.org/linux-fsdevel/20210630161320.29006-1-lhenriques@suse.de/ Reported-by: Nicolas Boichat Reported-by: kernel test robot Reviewed-by: Amir Goldstein Signed-off-by: Luis Henriques --- Changes since v11 - added note about zero-size copies and a link to the corresponding mailing-list discussion Changes since v10 - simply remove the "if (len == 0)" short-circuit instead of checking if the filesystem implements the syscall. This is because a filesystem may implement it but a particular instance (hint: overlayfs!) may not. Changes since v9 - the early return from the syscall when len is zero now checks if the filesystem is implemented, returning -EOPNOTSUPP if it is not and 0 otherwise. Issue reported by test robot. (obviously, dropped Amir's Reviewed-by and Olga's Tested-by tags) Changes since v8 - Simply added Amir's Reviewed-by and Olga's Tested-by Changes since v7 - set 'ret' to '-EOPNOTSUPP' before the clone 'if' statement so that the error returned is always related to the 'copy' operation Changes since v6 - restored i_sb checks for the clone operation Changes since v5 - check if ->copy_file_range is NULL before calling it Changes since v4 - nfsd falls-back to generic_copy_file_range() only *if* it gets -EOPNOTSUPP or -EXDEV. Changes since v3 - dropped the COPY_FILE_SPLICE flag - kept the f_op's checks early in generic_copy_file_checks, implementing Amir's suggestions - modified nfsd to use generic_copy_file_range() Changes since v2 - do all the required checks earlier, in generic_copy_file_checks(), adding new checks for ->remap_file_range - new COPY_FILE_SPLICE flag - don't remove filesystem's fallback to generic_copy_file_range() - updated commit changelog (and subject) Changes since v1 (after Amir review) - restored do_copy_file_range() helper - return -EOPNOTSUPP if fs doesn't implement CFR - updated commit description fs/nfsd/vfs.c | 8 +++++++- fs/read_write.c | 52 +++++++++++++++++++++++-------------------------- 2 files changed, 31 insertions(+), 29 deletions(-) diff --git a/fs/nfsd/vfs.c b/fs/nfsd/vfs.c index 15adf1f6ab21..f54a88b3b4a2 100644 --- a/fs/nfsd/vfs.c +++ b/fs/nfsd/vfs.c @@ -569,6 +569,7 @@ __be32 nfsd4_clone_file_range(struct nfsd_file *nf_src, u64 src_pos, ssize_t nfsd_copy_file_range(struct file *src, u64 src_pos, struct file *dst, u64 dst_pos, u64 count) { + ssize_t ret; /* * Limit copy to 4MB to prevent indefinitely blocking an nfsd @@ -579,7 +580,12 @@ ssize_t nfsd_copy_file_range(struct file *src, u64 src_pos, struct file *dst, * limit like this and pipeline multiple COPY requests. */ count = min_t(u64, count, 1 << 22); - return vfs_copy_file_range(src, src_pos, dst, dst_pos, count, 0); + ret = vfs_copy_file_range(src, src_pos, dst, dst_pos, count, 0); + + if (ret == -EOPNOTSUPP || ret == -EXDEV) + ret = generic_copy_file_range(src, src_pos, dst, dst_pos, + count, 0); + return ret; } __be32 nfsd4_vfs_fallocate(struct svc_rqst *rqstp, struct svc_fh *fhp, diff --git a/fs/read_write.c b/fs/read_write.c index 9db7adf160d2..049a2dda29f7 100644 --- a/fs/read_write.c +++ b/fs/read_write.c @@ -1395,28 +1395,6 @@ ssize_t generic_copy_file_range(struct file *file_in, loff_t pos_in, } EXPORT_SYMBOL(generic_copy_file_range); -static ssize_t do_copy_file_range(struct file *file_in, loff_t pos_in, - struct file *file_out, loff_t pos_out, - size_t len, unsigned int flags) -{ - /* - * Although we now allow filesystems to handle cross sb copy, passing - * a file of the wrong filesystem type to filesystem driver can result - * in an attempt to dereference the wrong type of ->private_data, so - * avoid doing that until we really have a good reason. NFS defines - * several different file_system_type structures, but they all end up - * using the same ->copy_file_range() function pointer. - */ - if (file_out->f_op->copy_file_range && - file_out->f_op->copy_file_range == file_in->f_op->copy_file_range) - return file_out->f_op->copy_file_range(file_in, pos_in, - file_out, pos_out, - len, flags); - - return generic_copy_file_range(file_in, pos_in, file_out, pos_out, len, - flags); -} - /* * Performs necessary checks before doing a file copy * @@ -1434,6 +1412,25 @@ static int generic_copy_file_checks(struct file *file_in, loff_t pos_in, loff_t size_in; int ret; + /* + * Although we now allow filesystems to handle cross sb copy, passing + * a file of the wrong filesystem type to filesystem driver can result + * in an attempt to dereference the wrong type of ->private_data, so + * avoid doing that until we really have a good reason. NFS defines + * several different file_system_type structures, but they all end up + * using the same ->copy_file_range() function pointer. + */ + if (file_out->f_op->copy_file_range) { + if (file_in->f_op->copy_file_range != + file_out->f_op->copy_file_range) + return -EXDEV; + } else if (file_in->f_op->remap_file_range) { + if (file_inode(file_in)->i_sb != file_inode(file_out)->i_sb) + return -EXDEV; + } else { + return -EOPNOTSUPP; + } + ret = generic_file_rw_checks(file_in, file_out); if (ret) return ret; @@ -1497,11 +1494,9 @@ ssize_t vfs_copy_file_range(struct file *file_in, loff_t pos_in, if (unlikely(ret)) return ret; - if (len == 0) - return 0; - file_start_write(file_out); + ret = -EOPNOTSUPP; /* * Try cloning first, this is supported by more file systems, and * more efficient if both clone and copy are supported (e.g. NFS). @@ -1520,9 +1515,10 @@ ssize_t vfs_copy_file_range(struct file *file_in, loff_t pos_in, } } - ret = do_copy_file_range(file_in, pos_in, file_out, pos_out, len, - flags); - WARN_ON_ONCE(ret == -EOPNOTSUPP); + if (file_out->f_op->copy_file_range) + ret = file_out->f_op->copy_file_range(file_in, pos_in, + file_out, pos_out, + len, flags); done: if (ret > 0) { fsnotify_access(file_in);