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=-13.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,UNPARSEABLE_RELAY 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 1419CC433DB for ; Mon, 15 Feb 2021 12:28:32 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id C88E664DC3 for ; Mon, 15 Feb 2021 12:28:31 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230433AbhBOM1y (ORCPT ); Mon, 15 Feb 2021 07:27:54 -0500 Received: from mx2.suse.de ([195.135.220.15]:54208 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230337AbhBOMVx (ORCPT ); Mon, 15 Feb 2021 07:21:53 -0500 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id 5AE60B03A; Mon, 15 Feb 2021 12:21:11 +0000 (UTC) Received: from localhost (brahms [local]) by brahms (OpenSMTPD) with ESMTPA id 4363275b; Mon, 15 Feb 2021 12:22:13 +0000 (UTC) From: Luis Henriques To: Amir Goldstein Cc: Greg KH , Jeff Layton , Nicolas Boichat , "Darrick J . Wong" , Alexander Viro , Ian Lance Taylor , Luis Lozano , Dave Chinner , linux-fsdevel , linux-kernel Subject: Re: [PATCH 1/6] fs: Add flag to file_system_type to indicate content is generated References: <20210212044405.4120619-1-drinkcat@chromium.org> <20210212124354.1.I7084a6235fbcc522b674a6b1db64e4aff8170485@changeid> <871rdljxtx.fsf@suse.de> <87sg61ihkj.fsf@suse.de> <87h7mdvcmd.fsf@suse.de> Date: Mon, 15 Feb 2021 12:22:13 +0000 In-Reply-To: <87h7mdvcmd.fsf@suse.de> (Luis Henriques's message of "Mon, 15 Feb 2021 10:39:22 +0000") Message-ID: <87eehhldvu.fsf@suse.de> MIME-Version: 1.0 Content-Type: text/plain Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Luis Henriques writes: > Amir Goldstein writes: > >> On Fri, Feb 12, 2021 at 2:40 PM Luis Henriques wrote: > ... >>> Sure, I just wanted to point out that *maybe* there are other options than >>> simply reverting that commit :-) >>> >>> Something like the patch below (completely untested!) should revert to the >>> old behaviour in filesystems that don't implement the CFR syscall. >>> >>> Cheers, >>> -- >>> Luis >>> >>> diff --git a/fs/read_write.c b/fs/read_write.c >>> index 75f764b43418..bf5dccc43cc9 100644 >>> --- a/fs/read_write.c >>> +++ b/fs/read_write.c >>> @@ -1406,8 +1406,11 @@ static ssize_t do_copy_file_range(struct file *file_in, loff_t pos_in, >>> file_out, pos_out, >>> len, flags); >>> >>> - return generic_copy_file_range(file_in, pos_in, file_out, pos_out, len, >>> - flags); >>> + if (file_inode(file_in)->i_sb != file_inode(file_out)->i_sb) >>> + return -EXDEV; >>> + else >>> + generic_copy_file_range(file_in, pos_in, file_out, pos_out, len, >>> + flags); >>> } >>> >> >> Which kernel is this patch based on? > > It was v5.11-rc7. > >> At this point, I am with Dave and Darrick on not falling back to >> generic_copy_file_range() at all. >> >> We do not have proof of any workload that benefits from it and the >> above patch does not protect from a wierd use case of trying to copy a file >> from sysfs to sysfs. >> > > Ok, cool. I can post a new patch doing just that. I guess that function > do_copy_file_range() can be dropped in that case. > >> I am indecisive about what should be done with generic_copy_file_range() >> called as fallback from within filesystems. >> >> I think the wise choice is to not do the fallback in any case, but this is up >> to the specific filesystem maintainers to decide. > > I see what you mean. You're suggesting to have userspace handle all the > -EOPNOTSUPP and -EXDEV errors. Would you rather have a patch that also > removes all the calls to generic_copy_file_range() function? And that > function can also be deleted too, of course. Here's a first stab at this patch. Hopefully I didn't forgot anything here. Let me know if you prefer the more conservative approach, i.e. not touching any of the filesystems and let them use generic_copy_file_range. Once everyone agrees on the final solution, I can follow-up with the manpages update. Cheers, -- Luis >From e1b37e80b12601d56f792bd19377d3e5208188ef Mon Sep 17 00:00:00 2001 From: Luis Henriques Date: Fri, 12 Feb 2021 18:03:23 +0000 Subject: [PATCH] vfs: prevent copy_file_range to copy across devices Nicolas Boichat reported an issue when trying to use the copy_file_range syscall on a tracefs file. It failed silently because the file content is generated on-the-fly (reporting a size of zero) and copy_file_range needs to know in advance how much data is present. This commit effectively reverts 5dae222a5ff0 ("vfs: allow copy_file_range to copy across devices"). Now the copy is done only if the filesystems for source and destination files are the same and they implement this syscall. Fixes: 5dae222a5ff0 ("vfs: allow copy_file_range to copy across devices") Cc: Nicolas Boichat Signed-off-by: Luis Henriques --- fs/ceph/file.c | 21 +++------------ fs/cifs/cifsfs.c | 3 --- fs/fuse/file.c | 21 +++------------ fs/nfs/nfs4file.c | 20 +++----------- fs/read_write.c | 65 ++++++++-------------------------------------- include/linux/fs.h | 3 --- 6 files changed, 20 insertions(+), 113 deletions(-) diff --git a/fs/ceph/file.c b/fs/ceph/file.c index 209535d5b8d3..639bd7bfaea9 100644 --- a/fs/ceph/file.c +++ b/fs/ceph/file.c @@ -2261,9 +2261,9 @@ static ssize_t ceph_do_objects_copy(struct ceph_inode_info *src_ci, u64 *src_off return bytes; } -static ssize_t __ceph_copy_file_range(struct file *src_file, loff_t src_off, - struct file *dst_file, loff_t dst_off, - size_t len, unsigned int flags) +static ssize_t ceph_copy_file_range(struct file *src_file, loff_t src_off, + struct file *dst_file, loff_t dst_off, + size_t len, unsigned int flags) { struct inode *src_inode = file_inode(src_file); struct inode *dst_inode = file_inode(dst_file); @@ -2456,21 +2456,6 @@ static ssize_t __ceph_copy_file_range(struct file *src_file, loff_t src_off, return ret; } -static ssize_t ceph_copy_file_range(struct file *src_file, loff_t src_off, - struct file *dst_file, loff_t dst_off, - size_t len, unsigned int flags) -{ - ssize_t ret; - - ret = __ceph_copy_file_range(src_file, src_off, dst_file, dst_off, - len, flags); - - if (ret == -EOPNOTSUPP || ret == -EXDEV) - ret = generic_copy_file_range(src_file, src_off, dst_file, - dst_off, len, flags); - return ret; -} - const struct file_operations ceph_file_fops = { .open = ceph_open, .release = ceph_release, diff --git a/fs/cifs/cifsfs.c b/fs/cifs/cifsfs.c index e46da536ed33..8b869cc67443 100644 --- a/fs/cifs/cifsfs.c +++ b/fs/cifs/cifsfs.c @@ -1229,9 +1229,6 @@ static ssize_t cifs_copy_file_range(struct file *src_file, loff_t off, len, flags); free_xid(xid); - if (rc == -EOPNOTSUPP || rc == -EXDEV) - rc = generic_copy_file_range(src_file, off, dst_file, - destoff, len, flags); return rc; } diff --git a/fs/fuse/file.c b/fs/fuse/file.c index 8cccecb55fb8..0dd703278e49 100644 --- a/fs/fuse/file.c +++ b/fs/fuse/file.c @@ -3330,9 +3330,9 @@ static long fuse_file_fallocate(struct file *file, int mode, loff_t offset, return err; } -static ssize_t __fuse_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) +static ssize_t fuse_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) { struct fuse_file *ff_in = file_in->private_data; struct fuse_file *ff_out = file_out->private_data; @@ -3439,21 +3439,6 @@ static ssize_t __fuse_copy_file_range(struct file *file_in, loff_t pos_in, return err; } -static ssize_t fuse_copy_file_range(struct file *src_file, loff_t src_off, - struct file *dst_file, loff_t dst_off, - size_t len, unsigned int flags) -{ - ssize_t ret; - - ret = __fuse_copy_file_range(src_file, src_off, dst_file, dst_off, - len, flags); - - if (ret == -EOPNOTSUPP || ret == -EXDEV) - ret = generic_copy_file_range(src_file, src_off, dst_file, - dst_off, len, flags); - return ret; -} - static const struct file_operations fuse_file_operations = { .llseek = fuse_file_llseek, .read_iter = fuse_file_read_iter, diff --git a/fs/nfs/nfs4file.c b/fs/nfs/nfs4file.c index 57b3821d975a..60998209e310 100644 --- a/fs/nfs/nfs4file.c +++ b/fs/nfs/nfs4file.c @@ -133,9 +133,9 @@ nfs4_file_flush(struct file *file, fl_owner_t id) } #ifdef CONFIG_NFS_V4_2 -static ssize_t __nfs4_copy_file_range(struct file *file_in, loff_t pos_in, - struct file *file_out, loff_t pos_out, - size_t count, unsigned int flags) +static ssize_t nfs4_copy_file_range(struct file *file_in, loff_t pos_in, + struct file *file_out, loff_t pos_out, + size_t count, unsigned int flags) { struct nfs42_copy_notify_res *cn_resp = NULL; struct nl4_server *nss = NULL; @@ -189,20 +189,6 @@ static ssize_t __nfs4_copy_file_range(struct file *file_in, loff_t pos_in, return ret; } -static ssize_t nfs4_copy_file_range(struct file *file_in, loff_t pos_in, - struct file *file_out, loff_t pos_out, - size_t count, unsigned int flags) -{ - ssize_t ret; - - ret = __nfs4_copy_file_range(file_in, pos_in, file_out, pos_out, count, - flags); - if (ret == -EOPNOTSUPP || ret == -EXDEV) - ret = generic_copy_file_range(file_in, pos_in, file_out, - pos_out, count, flags); - return ret; -} - static loff_t nfs4_file_llseek(struct file *filep, loff_t offset, int whence) { loff_t ret; diff --git a/fs/read_write.c b/fs/read_write.c index 75f764b43418..87bf9efd7f71 100644 --- a/fs/read_write.c +++ b/fs/read_write.c @@ -1358,58 +1358,6 @@ COMPAT_SYSCALL_DEFINE4(sendfile64, int, out_fd, int, in_fd, } #endif -/** - * generic_copy_file_range - copy data between two files - * @file_in: file structure to read from - * @pos_in: file offset to read from - * @file_out: file structure to write data to - * @pos_out: file offset to write data to - * @len: amount of data to copy - * @flags: copy flags - * - * This is a generic filesystem helper to copy data from one file to another. - * It has no constraints on the source or destination file owners - the files - * can belong to different superblocks and different filesystem types. Short - * copies are allowed. - * - * This should be called from the @file_out filesystem, as per the - * ->copy_file_range() method. - * - * Returns the number of bytes copied or a negative error indicating the - * failure. - */ - -ssize_t generic_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) -{ - return do_splice_direct(file_in, &pos_in, file_out, &pos_out, - len > MAX_RW_COUNT ? MAX_RW_COUNT : len, 0); -} -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 * @@ -1474,6 +1422,14 @@ ssize_t vfs_copy_file_range(struct file *file_in, loff_t pos_in, { ssize_t ret; + /* + * Allow the copy only if the filesystems for file_in and file_out are + * the same, and copy_file_range is implemented. + */ + if (!file_out->f_op->copy_file_range || + (file_out->f_op->copy_file_range != file_in->f_op->copy_file_range)) + return -EXDEV; + if (flags != 0) return -EINVAL; @@ -1513,8 +1469,9 @@ 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); + ret = file_out->f_op->copy_file_range(file_in, pos_in, + file_out, pos_out, + len, flags); WARN_ON_ONCE(ret == -EOPNOTSUPP); done: if (ret > 0) { diff --git a/include/linux/fs.h b/include/linux/fs.h index fd47deea7c17..3aaf627be409 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -1910,9 +1910,6 @@ extern ssize_t vfs_read(struct file *, char __user *, size_t, loff_t *); extern ssize_t vfs_write(struct file *, const char __user *, size_t, loff_t *); extern ssize_t vfs_copy_file_range(struct file *, loff_t , struct file *, loff_t, size_t, unsigned int); -extern ssize_t generic_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); extern int generic_remap_file_range_prep(struct file *file_in, loff_t pos_in, struct file *file_out, loff_t pos_out, loff_t *count,