Changed the allocations of some local variables to GLib's allocation
functions, such as g_try_malloc0(), and annotated those variables
as g_autofree. Subsequently, I was able to remove the calls to free().
Signed-off-by: Mahmoud Mandour <ma.mandourr@gmail.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-Id: <20210420154643.58439-7-ma.mandourr@gmail.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Changed the allocations of fv_VuDev structs, VuDev structs, and
fv_QueueInfo strcuts from using calloc()/realloc() & free() to using
the equivalent functions from GLib.
In instances, removed the pair of allocation and assertion for
non-NULL checking with a GLib function that aborts on error.
Removed NULL-checking for fv_VuDev struct allocation and used
a GLib function that crashes on error; namely, g_new0(). This
is because allocating one struct should not be a problem on an
healthy system. Also following the pattern of aborting-on-null
behaviour that is taken with allocating VuDev structs and
fv_QueueInfo structs.
Signed-off-by: Mahmoud Mandour <ma.mandourr@gmail.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-Id: <20210420154643.58439-6-ma.mandourr@gmail.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Replaced the calls to malloc()/calloc() and their respective
calls to free() of iovec structs with GLib's allocation and
deallocation functions and used g_autofree when appropriate.
Replaced the allocation of in_sg_cpy to g_new() instead of a call
to calloc() and a null-checking assertion. Not g_new0()
because the buffer is immediately overwritten using memcpy.
Signed-off-by: Mahmoud Mandour <ma.mandourr@gmail.com>
Message-Id: <20210427181333.148176-1-ma.mandourr@gmail.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
virtiofsd incorrectly assumed a fixed set of header layout in the virt
queue; assuming that the fuse and write headers were conveniently
separated from the data; the spec doesn't allow us to take that
convenience, so fix it up to deal with it the hard way.
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Message-Id: <20210428110100.27757-3-dgilbert@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
It is bad practice to put an expression with a side-effect in
assert() because the side-effect won't happen if the code is
compiled with -DNDEBUG.
Use an intermediate variable. Consolidate this in an macro to
have proper line numbers when the assertion is hit.
virtiofsd: ../../tools/virtiofsd/passthrough_ll.c:2797: lo_getxattr:
Assertion `fchdir_res == 0' failed.
Aborted
2796 /* fchdir should not fail here */
=>2797 FCHDIR_NOFAIL(lo->proc_self_fd);
2798 ret = getxattr(procname, name, value, size);
2799 FCHDIR_NOFAIL(lo->root.fd);
Fixes: bdfd667883 ("virtiofsd: Fix xattr operations")
Cc: misono.tomohiro@jp.fujitsu.com
Signed-off-by: Greg Kurz <groug@kaod.org>
Message-Id: <20210409100627.451573-1-groug@kaod.org>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
My security fix for the security.capability remap has a silly early
segfault in a simple case where there is an xattrmapping but it doesn't
remap the security.capability.
Fixes: e586edcb41 ("virtiofs: drop remapped security.capability xattr as needed")
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Message-Id: <20210401145845.78445-1-dgilbert@redhat.com>
Reviewed-by: Connor Kuehl <ckuehl@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
When passed an empty filename, lookup_name() returns the inode of
the parent directory, unless the parent is the root in which case
the st_dev doesn't match and lo_find() returns NULL. This is
because lookup_name() passes AT_EMPTY_PATH down to fstatat() or
statx().
This behavior doesn't quite make sense because users of lookup_name()
then pass the name to unlinkat(), renameat() or renameat2(), all of
which will always fail on empty names.
Drop AT_EMPTY_PATH from the flags in lookup_name() so that it has
the consistent behavior of "returning an existing child inode or
NULL" for all directories.
Signed-off-by: Greg Kurz <groug@kaod.org>
Message-Id: <20210312141003.819108-2-groug@kaod.org>
Reviewed-by: Connor Kuehl <ckuehl@redhat.com>
Reviewed-by: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
POSIX.1-2017 clearly stipulates that empty filenames aren't
allowed ([1] and [2]). Since virtiofsd is supposed to mirror
the host file system hierarchy and the host can be assumed to
be linux, we don't really expect clients to pass requests with
an empty path in it. If they do so anyway, this would eventually
cause an error when trying to create/lookup the actual inode
on the underlying POSIX filesystem. But this could still confuse
some code that wouldn't be ready to cope with this.
Filter out empty names coming from the client at the top level,
so that the rest doesn't have to care about it. This is done
everywhere we already call is_safe_path_component(), but
in a separate helper since the usual error for empty path
names is ENOENT instead of EINVAL.
[1] https://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap03.html#tag_03_170
[2] https://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap04.html#tag_04_13
Signed-off-by: Greg Kurz <groug@kaod.org>
Message-Id: <20210312141003.819108-4-groug@kaod.org>
Reviewed-by: Connor Kuehl <ckuehl@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Option "-V" currently displays the fuse protocol version virtiofsd is
using. For example, I see this.
$ ./virtiofsd -V
"using FUSE kernel interface version 7.33"
People also want to know software version of virtiofsd so that they can
figure out if a certain fix is part of currently running virtiofsd or
not. Eric Ernst ran into this issue.
David Gilbert thinks that it probably is best that we simply carry the
qemu version and display that information given we are part of qemu
tree.
So this patch enhances version information and also adds qemu version
and copyright info. Not sure if copyright information is supposed
to be displayed along with version info. Given qemu-storage-daemon
and other utilities are doing it, so I continued with same pattern.
This is how now output looks like.
$ ./virtiofsd -V
virtiofsd version 5.2.50 (v5.2.0-2357-gcbcf09872a-dirty)
Copyright (c) 2003-2020 Fabrice Bellard and the QEMU Project developers
using FUSE kernel interface version 7.33
Reported-by: Eric Ernst <eric.g.ernst@gmail.com>
Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
Message-Id: <20210303195339.GB3793@redhat.com>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Reviewed-by: Sergio Lopez <slp@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
QEMU can stop a virtqueue by sending a VHOST_USER_GET_VRING_BASE request
to virtiofsd. As with all other vhost-user protocol messages, the thread
that runs the main event loop in virtiofsd takes the vu_dispatch lock in
write mode. This ensures that no other thread can access virtqueues or
memory tables at the same time.
In the case of VHOST_USER_GET_VRING_BASE, the main thread basically
notifies the queue thread that it should terminate and waits for its
termination:
main()
virtio_loop()
vu_dispatch_wrlock()
vu_dispatch()
vu_process_message()
vu_get_vring_base_exec()
fv_queue_cleanup_thread()
pthread_join()
Unfortunately, the queue thread ends up calling virtio_send_msg()
at some point, which itself needs to grab the lock:
fv_queue_thread()
g_list_foreach()
fv_queue_worker()
fuse_session_process_buf_int()
do_release()
lo_release()
fuse_reply_err()
send_reply()
send_reply_iov()
fuse_send_reply_iov_nofree()
fuse_send_msg()
virtio_send_msg()
vu_dispatch_rdlock() <-- Deadlock !
Simply have the main thread to release the lock before going to
sleep and take it back afterwards. A very similar patch was already
sent by Vivek Goyal sometime back:
https://listman.redhat.com/archives/virtio-fs/2021-January/msg00073.html
The only difference here is that this done in fv_queue_set_started()
because fv_queue_cleanup_thread() can also be called from virtio_loop()
without the lock being held.
Signed-off-by: Greg Kurz <groug@kaod.org>
Reviewed-by: Vivek Goyal <vgoyal@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-Id: <20210312092212.782255-8-groug@kaod.org>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
On Linux, the 'security.capability' xattr holds a set of
capabilities that can change when an executable is run, giving
a limited form of privilege escalation to those programs that
the writer of the file deemed worthy.
Any write causes the 'security.capability' xattr to be dropped,
stopping anyone from gaining privilege by modifying a blessed
file.
Fuse relies on the daemon to do this dropping, and in turn the
daemon relies on the host kernel to drop the xattr for it. However,
with the addition of -o xattrmap, the xattr that the guest
stores its capabilities in is now not the same as the one that
the host kernel automatically clears.
Where the mapping changes 'security.capability', explicitly clear
the remapped name to preserve the same behaviour.
This bug is assigned CVE-2021-20263.
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Reviewed-by: Vivek Goyal <vgoyal@redhat.com>
Currently we created a thread pool (With 64 max threads per pool) for
each virtqueue. We hoped that this will provide us with better scalability
and performance.
But in practice, we are getting better numbers in most of the cases
when we don't create a thread pool at all and a single thread per
virtqueue receives the request and processes it.
Hence, I am proposing that we switch to no thread pool by default
(equivalent of --thread-pool-size=0). This will provide out of
box better performance to most of the users. In fact other users
have confirmed that not using a thread pool gives them better
numbers. So why not use this as default. It can be changed when
somebody can fix the issues with thread pool performance.
Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
Message-Id: <20210210182744.27324-2-vgoyal@redhat.com>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
This patch adds basic support for FUSE_HANDLE_KILLPRIV_V2. virtiofsd
can enable/disable this by specifying option "-o killpriv_v2/no_killpriv_v2".
By default this is enabled as long as client supports it
Enabling this option helps with performance in write path. Without this
option, currently every write is first preceeded with a getxattr() operation
to find out if security.capability is set. (Write is supposed to clear
security.capability). With this option enabled, server is signing up for
clearing security.capability on every WRITE and also clearing suid/sgid
subject to certain rules. This gets rid of extra getxattr() call for every
WRITE and improves performance. This is true when virtiofsd is run with
option -o xattr.
What does enabling FUSE_HANDLE_KILLPRIV_V2 mean for file server implementation.
It needs to adhere to following rules. Thanks to Miklos for this summary.
- clear "security.capability" on write, truncate and chown unconditionally
- clear suid/sgid in case of following. Note, sgid is cleared only if
group executable bit is set.
o setattr has FATTR_SIZE and FATTR_KILL_SUIDGID set.
o setattr has FATTR_UID or FATTR_GID
o open has O_TRUNC and FUSE_OPEN_KILL_SUIDGID
o create has O_TRUNC and FUSE_OPEN_KILL_SUIDGID flag set.
o write has FUSE_WRITE_KILL_SUIDGID
>From Linux VFS client perspective, here are the requirements.
- caps are always cleared on chown/write/truncate
- suid is always cleared on chown, while for truncate/write it is cleared
only if caller does not have CAP_FSETID.
- sgid is always cleared on chown, while for truncate/write it is cleared
only if caller does not have CAP_FSETID as well as file has group execute
permission.
virtiofsd implementation has not changed much to adhere to above ruls. And
reason being that current assumption is that we are running on Linux
and on top of filesystems like ext4/xfs which already follow above rules.
On write, truncate, chown, seucurity.capability is cleared. And virtiofsd
drops CAP_FSETID if need be and that will lead to clearing of suid/sgid.
But if virtiofsd is running on top a filesystem which breaks above assumptions,
then it will have to take extra actions to emulate above. That's a TODO
for later when need arises.
Note: create normally is supposed to be called only when file does not
exist. So generally there should not be any question of clearing
setuid/setgid. But it is possible that after client checks that
file is not present, some other client creates file on server
and this race can trigger sending FUSE_CREATE. In that case, if
O_TRUNC is set, we should clear suid/sgid if FUSE_OPEN_KILL_SUIDGID
is also set.
v3:
- Resolved conflicts due to lo_inode_open() changes.
- Moved capability code in lo_do_open() so that both lo_open() and
lo_create() can benefit from common code.
- Dropped changes to kernel headers as these are part of qemu already.
Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
Acked-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Message-Id: <20210208224024.43555-3-vgoyal@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Change error code handling slightly in lo_setattr(). Right now we seem
to jump to out_err and assume that "errno" is valid and use that to
send reply.
But if caller has to do some other operations before jumping to out_err,
then it does the dance of first saving errno to saverr and the restore
errno before jumping to out_err. This makes it more confusing.
I am about to make more changes where caller will have to do some
work after error before jumping to out_err. I found it easier to
change the convention a bit. That is caller saves error in "saverr"
before jumping to out_err. And out_err uses "saverr" to send error
back and does not rely on "errno" having actual error.
v3: Resolved conflicts in lo_setattr() due to lo_inode_open() changes.
Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Message-Id: <20210208224024.43555-2-vgoyal@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
