linux-stable.git/fs/fuse, branch v4.19.71

fuse: retrieve: cap requested size to negotiated max_write

2019-06-15T09:54:07+00:00

[ Upstream commit 7640682e67b33cab8628729afec8ca92b851394f ]

FUSE filesystem server and kernel client negotiate during initialization
phase, what should be the maximum write size the client will ever issue.
Correspondingly the filesystem server then queues sys_read calls to read
requests with buffer capacity large enough to carry request header + that
max_write bytes. A filesystem server is free to set its max_write in
anywhere in the range between [1*page, fc->max_pages*page]. In particular
go-fuse[2] sets max_write by default as 64K, wheres default fc->max_pages
corresponds to 128K. Libfuse also allows users to configure max_write, but
by default presets it to possible maximum.

If max_write is < fc->max_pages*page, and in NOTIFY_RETRIEVE handler we
allow to retrieve more than max_write bytes, corresponding prepared
NOTIFY_REPLY will be thrown away by fuse_dev_do_read, because the
filesystem server, in full correspondence with server/client contract, will
be only queuing sys_read with ~max_write buffer capacity, and
fuse_dev_do_read throws away requests that cannot fit into server request
buffer. In turn the filesystem server could get stuck waiting indefinitely
for NOTIFY_REPLY since NOTIFY_RETRIEVE handler returned OK which is
understood by clients as that NOTIFY_REPLY was queued and will be sent
back.

Cap requested size to negotiate max_write to avoid the problem.  This
aligns with the way NOTIFY_RETRIEVE handler works, which already
unconditionally caps requested retrieve size to fuse_conn->max_pages.  This
way it should not hurt NOTIFY_RETRIEVE semantic if we return less data than
was originally requested.

Please see [1] for context where the problem of stuck filesystem was hit
for real, how the situation was traced and for more involving patch that
did not make it into the tree.

[1] https://marc.info/?l=linux-fsdevel&m=155057023600853&w=2
[2] https://github.com/hanwen/go-fuse

Signed-off-by: Kirill Smelkov 
Cc: Han-Wen Nienhuys 
Cc: Jakob Unterwurzacher 
Signed-off-by: Miklos Szeredi 
Signed-off-by: Sasha Levin

fuse: fallocate: fix return with locked inode

2019-06-11T10:20:51+00:00

commit 35d6fcbb7c3e296a52136347346a698a35af3fda upstream.

Do the proper cleanup in case the size check fails.

Tested with xfstests:generic/228

Reported-by: kbuild test robot 
Reported-by: Dan Carpenter 
Fixes: 0cbade024ba5 ("fuse: honor RLIMIT_FSIZE in fuse_file_fallocate")
Cc: Liu Bo 
Cc:  # v3.5
Signed-off-by: Miklos Szeredi 
Signed-off-by: Greg Kroah-Hartman

fuse: Add FOPEN_STREAM to use stream_open()

2019-05-25T16:23:40+00:00

commit bbd84f33652f852ce5992d65db4d020aba21f882 upstream.

Starting from commit 9c225f2655e3 ("vfs: atomic f_pos accesses as per
POSIX") files opened even via nonseekable_open gate read and write via lock
and do not allow them to be run simultaneously. This can create read vs
write deadlock if a filesystem is trying to implement a socket-like file
which is intended to be simultaneously used for both read and write from
filesystem client.  See commit 10dce8af3422 ("fs: stream_open - opener for
stream-like files so that read and write can run simultaneously without
deadlock") for details and e.g. commit 581d21a2d02a ("xenbus: fix deadlock
on writes to /proc/xen/xenbus") for a similar deadlock example on
/proc/xen/xenbus.

To avoid such deadlock it was tempting to adjust fuse_finish_open to use
stream_open instead of nonseekable_open on just FOPEN_NONSEEKABLE flags,
but grepping through Debian codesearch shows users of FOPEN_NONSEEKABLE,
and in particular GVFS which actually uses offset in its read and write
handlers

	https://codesearch.debian.net/search?q=-%3Enonseekable+%3D
	https://gitlab.gnome.org/GNOME/gvfs/blob/1.40.0-6-gcbc54396/client/gvfsfusedaemon.c#L1080
	https://gitlab.gnome.org/GNOME/gvfs/blob/1.40.0-6-gcbc54396/client/gvfsfusedaemon.c#L1247-1346
	https://gitlab.gnome.org/GNOME/gvfs/blob/1.40.0-6-gcbc54396/client/gvfsfusedaemon.c#L1399-1481

so if we would do such a change it will break a real user.

Add another flag (FOPEN_STREAM) for filesystem servers to indicate that the
opened handler is having stream-like semantics; does not use file position
and thus the kernel is free to issue simultaneous read and write request on
opened file handle.

This patch together with stream_open() should be added to stable kernels
starting from v3.14+. This will allow to patch OSSPD and other FUSE
filesystems that provide stream-like files to return FOPEN_STREAM |
FOPEN_NONSEEKABLE in open handler and this way avoid the deadlock on all
kernel versions. This should work because fuse_finish_open ignores unknown
open flags returned from a filesystem and so passing FOPEN_STREAM to a
kernel that is not aware of this flag cannot hurt. In turn the kernel that
is not aware of FOPEN_STREAM will be < v3.14 where just FOPEN_NONSEEKABLE
is sufficient to implement streams without read vs write deadlock.

Cc: stable@vger.kernel.org # v3.14+
Signed-off-by: Kirill Smelkov 
Signed-off-by: Miklos Szeredi 
Signed-off-by: Greg Kroah-Hartman

fuse: honor RLIMIT_FSIZE in fuse_file_fallocate

2019-05-25T16:23:30+00:00

commit 0cbade024ba501313da3b7e5dd2a188a6bc491b5 upstream.

fstests generic/228 reported this failure that fuse fallocate does not
honor what 'ulimit -f' has set.

This adds the necessary inode_newsize_ok() check.

Signed-off-by: Liu Bo 
Fixes: 05ba1f082300 ("fuse: add FALLOCATE operation")
Cc:  # v3.5
Signed-off-by: Miklos Szeredi 
Signed-off-by: Greg Kroah-Hartman

fuse: fix writepages on 32bit

2019-05-25T16:23:30+00:00

commit 9de5be06d0a89ca97b5ab902694d42dfd2bb77d2 upstream.

Writepage requests were cropped to i_size & 0xffffffff, which meant that
mmaped writes to any file larger than 4G might be silently discarded.

Fix by storing the file size in a properly sized variable (loff_t instead
of size_t).

Reported-by: Antonio SJ Musumeci 
Fixes: 6eaf4782eb09 ("fuse: writepages: crop secondary requests")
Cc:  # v3.13
Signed-off-by: Miklos Szeredi 
Signed-off-by: Greg Kroah-Hartman

fs: prevent page refcount overflow in pipe_buf_get

2019-05-04T07:20:11+00:00

commit 15fab63e1e57be9fdb5eec1bbc5916e9825e9acb upstream.

Change pipe_buf_get() to return a bool indicating whether it succeeded
in raising the refcount of the page (if the thing in the pipe is a page).
This removes another mechanism for overflowing the page refcount.  All
callers converted to handle a failure.

Reported-by: Jann Horn 
Signed-off-by: Matthew Wilcox 
Cc: stable@kernel.org
Signed-off-by: Linus Torvalds 
Signed-off-by: Greg Kroah-Hartman

fuse: handle zero sized retrieve correctly

2019-02-12T18:47:24+00:00

commit 97e1532ef81acb31c30f9e75bf00306c33a77812 upstream.

Dereferencing req->page_descs[0] will Oops if req->max_pages is zero.

Reported-by: syzbot+c1e36d30ee3416289cc0@syzkaller.appspotmail.com
Tested-by: syzbot+c1e36d30ee3416289cc0@syzkaller.appspotmail.com
Fixes: b2430d7567a3 ("fuse: add per-page descriptor  to fuse_req")
Cc:  # v3.9
Signed-off-by: Miklos Szeredi 
Signed-off-by: Greg Kroah-Hartman

fuse: decrement NR_WRITEBACK_TEMP on the right page

2019-02-12T18:47:24+00:00

commit a2ebba824106dabe79937a9f29a875f837e1b6d4 upstream.

NR_WRITEBACK_TEMP is accounted on the temporary page in the request, not
the page cache page.

Fixes: 8b284dc47291 ("fuse: writepages: handle same page rewrites")
Cc:  # v3.13
Signed-off-by: Miklos Szeredi 
Signed-off-by: Greg Kroah-Hartman

fuse: call pipe_buf_release() under pipe lock

2019-02-12T18:47:23+00:00

commit 9509941e9c534920ccc4771ae70bd6cbbe79df1c upstream.

Some of the pipe_buf_release() handlers seem to assume that the pipe is
locked - in particular, anon_pipe_buf_release() accesses pipe->tmp_page
without taking any extra locks. From a glance through the callers of
pipe_buf_release(), it looks like FUSE is the only one that calls
pipe_buf_release() without having the pipe locked.

This bug should only lead to a memory leak, nothing terrible.

Fixes: dd3bb14f44a6 ("fuse: support splice() writing to fuse device")
Cc: stable@vger.kernel.org
Signed-off-by: Jann Horn 
Signed-off-by: Miklos Szeredi 
Signed-off-by: Greg Kroah-Hartman

fuse: continue to send FUSE_RELEASEDIR when FUSE_OPEN returns ENOSYS

2018-12-19T18:19:51+00:00

commit 2e64ff154ce6ce9a8dc0f9556463916efa6ff460 upstream.

When FUSE_OPEN returns ENOSYS, the no_open bit is set on the connection.

Because the FUSE_RELEASE and FUSE_RELEASEDIR paths share code, this
incorrectly caused the FUSE_RELEASEDIR request to be dropped and never sent
to userspace.

Pass an isdir bool to distinguish between FUSE_RELEASE and FUSE_RELEASEDIR
inside of fuse_file_put.

Fixes: 7678ac50615d ("fuse: support clients that don't implement 'open'")
Cc:  # v3.14
Signed-off-by: Chad Austin 
Signed-off-by: Miklos Szeredi 
Signed-off-by: Greg Kroah-Hartman