We are having bunch of issues with killpriv_v2 enabled by default. First
of all it relies on clearing suid/sgid bits as needed by dropping
capability CAP_FSETID. This does not work for remote filesystems like
NFS (and possibly others).
Secondly, we are noticing other issues related to clearing of SGID
which leads to failures for xfstests generic/355 and generic/193.
Thirdly, there are other issues w.r.t caching of metadata (suid/sgid)
bits in fuse client with killpriv_v2 enabled. Guest can cache that
data for sometime even if cleared on server.
Second and Third issue are fixable. Just that it might take a little
while to get it fixed in kernel. First one will probably not see
any movement for a long time.
Given these issues, killpriv_v2 does not seem to be a good candidate
for enabling by default. We have already disabled it by default in
rust version of virtiofsd.
Hence this patch disabled killpriv_v2 by default. User can choose to
enable it by passing option "-o killpriv_v2".
Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
Message-Id: <YuPd0itNIAz4tQRt@redhat.com>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
Message-Id: <20220707163720.1421716-5-berrange@redhat.com>
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Thomas Huth <thuth@redhat.com>
Inspired by Julia Lawall's fixing of Linux
kernel comments, I looked at qemu, although I did it manually.
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Reviewed-by: Daniel Henrique Barboza <danielhb413@gmail.com>
Reviewed-by: Klaus Jensen <k.jensen@samsung.com>
Message-Id: <20220614104045.85728-2-dgilbert@redhat.com>
Signed-off-by: Laurent Vivier <laurent@vivier.eu>
Header guard symbols should match their file name to make guard
collisions less likely.
Cleaned up with scripts/clean-header-guards.pl, followed by some
renaming of new guard symbols picked by the script to better ones.
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Message-Id: <20220506134911.2856099-2-armbru@redhat.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
[Change to generated file ebpf/rss.bpf.skeleton.h backed out]
When using Meson options rather than config-host.h, the "when" clauses
have to be changed to if statements (which is not necessarily great,
though at least it highlights which parts of the build are per-target
and which are not).
Do that before moving vhost logic to meson.build, though for now
the variables are just based on config-host.mak data.
Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Suggested-by: Daniel P. Berrangé <berrange@redhat.com>
Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
Simplify the function to only return the directory path. Callers are
adjusted to use the GLib function to build paths, g_build_filename().
Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
Message-Id: <20220420132624.2439741-39-marcandre.lureau@redhat.com>
virtiofsd has introduced killpriv_v2/no_killpriv_v2 for a while. Add
description of it to docs/helper.
Signed-off-by: Liu Yiding <liuyd.fnst@fujitsu.com>
Message-Id: <20220421095151.2231099-1-liuyd.fnst@fujitsu.com>
[Small documentation fixes: s/as client supports/as the client supports/
and s/. /. /.
--Stefan]
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
In virtiofsd, we assume that the presence of the STATX_MNT_ID macro
implies existence of the statx.stx_mnt_id field. Unfortunately, that is
not necessarily the case: glibc has introduced the macro in its commit
88a2cf6c4bab6e94a65e9c0db8813709372e9180, but the statx.stx_mnt_id field
is still missing from its own headers.
Let meson.build actually chek for both STATX_MNT_ID and
statx.stx_mnt_id, and set CONFIG_STATX_MNT_ID if both are present.
Then, use this config macro in virtiofsd.
Closes: https://gitlab.com/qemu-project/qemu/-/issues/882
Signed-off-by: Hanna Reitz <hreitz@redhat.com>
Message-Id: <20220223092340.9043-1-hreitz@redhat.com>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Honor the expected behavior of syncfs() to synchronously flush all data
and metadata to disk on linux systems.
If virtiofsd is started with '-o announce_submounts', the client is
expected to send a FUSE_SYNCFS request for each individual submount.
In this case, we just create a new file descriptor on the submount
inode with lo_inode_open(), call syncfs() on it and close it. The
intermediary file is needed because O_PATH descriptors aren't
backed by an actual file and syncfs() would fail with EBADF.
If virtiofsd is started without '-o announce_submounts' or if the
client doesn't have the FUSE_CAP_SUBMOUNTS capability, the client
only sends a single FUSE_SYNCFS request for the root inode. The
server would thus need to track submounts internally and call
syncfs() on each of them. This will be implemented later.
Note that syncfs() might suffer from a time penalty if the submounts
are being hammered by some unrelated workload on the host. The only
solution to prevent that is to avoid shared mounts.
Signed-off-by: Greg Kurz <groug@kaod.org>
Message-Id: <20220215181529.164070-2-groug@kaod.org>
Reviewed-by: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Provide an option "-o security_label/no_security_label" to enable/disable
security label functionality. By default these are turned off.
If enabled, server will indicate to client that it is capable of handling
one security label during file creation. Typically this is expected to
be a SELinux label. File server will set this label on the file. It will
try to set it atomically wherever possible. But its not possible in
all the cases.
Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
Message-Id: <20220208204813.682906-11-vgoyal@redhat.com>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
If guest and host policies can't work with each other, then guest security
context (selinux label) needs to be set into an xattr. Say remap guest
security.selinux xattr to trusted.virtiofs.security.selinux.
That means setting "fscreate" is not going to help as that's ony useful
for security.selinux xattr on host.
So we need another method which is atomic. Use O_TMPFILE to create new
file, set xattr and then linkat() to proper place.
But this works only for regular files. So dir, symlinks will continue
to be non-atomic.
Also if host filesystem does not support O_TMPFILE, we fallback to
non-atomic behavior.
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
Message-Id: <20220208204813.682906-10-vgoyal@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
This patch adds support for creating new file with security context
as sent by client. It basically takes three paths.
- If no security context enabled, then it continues to create files without
security context.
- If security context is enabled and but security.selinux has not been
remapped, then it uses /proc/thread-self/attr/fscreate knob to set
security context and then create the file. This will make sure that
newly created file gets the security context as set in "fscreate" and
this is atomic w.r.t file creation.
This is useful and host and guest SELinux policies don't conflict and
can work with each other. In that case, guest security.selinux xattr
is not remapped and it is passthrough as "security.selinux" xattr
on host.
- If security context is enabled but security.selinux xattr has been
remapped to something else, then it first creates the file and then
uses setxattr() to set the remapped xattr with the security context.
This is a non-atomic operation w.r.t file creation.
This mode will be most versatile and allow host and guest to have their
own separate SELinux xattrs and have their own separate SELinux policies.
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
Message-Id: <20220208204813.682906-9-vgoyal@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Soon we will be able to create and also set security context on the file
atomically using /proc/self/task/tid/attr/fscreate knob. If this knob
is available on the system, first set the knob with the desired context
and then create the file. It will be created with the context set in
fscreate. This works basically for SELinux and its per thread.
This patch just introduces the helper functions. Subsequent patches will
make use of these helpers.
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
Message-Id: <20220208204813.682906-8-vgoyal@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
dgilbert: Manually merged gettid syscall number fixup from Vivek
Move core file creation bits in a separate function. Soon this is going
to get more complex as file creation need to set security context also.
And there will be multiple modes of file creation in next patch.
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
Message-Id: <20220208204813.682906-7-vgoyal@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Add capability to enable and parse security context as sent by client
and put into fuse_req. Filesystems now can get security context from
request and set it on files during creation.
Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
Message-Id: <20220208204813.682906-6-vgoyal@redhat.com>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
->capable keeps track of what capabilities kernel supports and ->wants keep
track of what capabilities filesytem wants.
Right now these fields are 32bit in size. But now fuse has run out of
bits and capabilities can now have bit number which are higher than 31.
That means 32 bit fields are not suffcient anymore. Increase size to 64
bit so that we can add newer capabilities and still be able to use existing
code to check and set the capabilities.
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
Message-Id: <20220208204813.682906-5-vgoyal@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Add some code to parse extended "struct fuse_init_in". And use a local
variable "flag" to represent 64 bit flags. This will make it easier
to add more features without having to worry about two 32bit flags (->flags
and ->flags2) in "fuse_struct_in".
Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
Message-Id: <20220208204813.682906-4-vgoyal@redhat.com>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
dgilbert: Fixed up long line
Kernel version 5.17 has increased the size of "struct fuse_init_in" struct.
Previously this struct was 16 bytes and now it has been extended to
64 bytes in size.
Once qemu headers are updated to latest, it will expect to receive 64 byte
size struct (for protocol version major 7 and minor > 6). But if guest is
booting older kernel (older than 5.17), then it still sends older
fuse_init_in of size 16 bytes. And do_init() fails. It is expecting
64 byte struct. And this results in mount of virtiofs failing.
Fix this by parsing 16 bytes only for now. Separate patches will be
posted which will parse rest of the bytes and enable new functionality.
Right now we don't support any of the new functionality, so we don't
lose anything by not parsing bytes beyond 16.
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
Message-Id: <20220208204813.682906-2-vgoyal@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
With the current implementation, blocking flock can lead to
deadlock. Thus, it's better to return EOPNOTSUPP if a user attempts
to perform a blocking flock request.
Signed-off-by: Sebastian Hasler <sebastian.hasler@stuvus.uni-stuttgart.de>
Message-Id: <20220113153249.710216-1-sebastian.hasler@stuvus.uni-stuttgart.de>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Reviewed-by: Vivek Goyal <vgoyal@redhat.com>
Reviewed-by: Greg Kurz <groug@kaod.org>
The method is now in 0.59, using it simplifies some conditionals.
There is a small change, which is to build virtfs-proxy-helper in a
tools-only build. This is done for consistency with other tools,
which are not culled by the absence of system emulator binaries.
.disable_auto_if() would also be useful to check for packages,
for example
-linux_io_uring = not_found
-if not get_option('linux_io_uring').auto() or have_block
- linux_io_uring = dependency('liburing', required: get_option('linux_io_uring'),
- method: 'pkg-config', kwargs: static_kwargs)
-endif
+linux_io_uring = dependency('liburing',
+ required: get_option('linux_io_uring').disable_auto_if(not have_block),
+ method: 'pkg-config', kwargs: static_kwargs)
This change however is much larger and I am not sure about the improved
readability, so I am not performing it right now.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
The virtiofsd currently crashes when used with glibc 2.35.
That is due to the rseq system call being added to every thread
creation [1][2].
[1]: https://www.efficios.com/blog/2019/02/08/linux-restartable-sequences/
[2]: https://sourceware.org/pipermail/libc-alpha/2022-February/136040.html
This happens not at daemon start, but when a guest connects
/usr/lib/qemu/virtiofsd -f --socket-path=/tmp/testvfsd -o sandbox=chroot \
-o source=/var/guests/j-virtiofs --socket-group=kvm
virtio_session_mount: Waiting for vhost-user socket connection...
# start ok, now guest will connect
virtio_session_mount: Received vhost-user socket connection
virtio_loop: Entry
fv_queue_set_started: qidx=0 started=1
fv_queue_set_started: qidx=1 started=1
Bad system call (core dumped)
We have to put rseq on the seccomp allowlist to avoid that the daemon
is crashing in this case.
Reported-by: Michael Hudson-Doyle <michael.hudson@canonical.com>
Signed-off-by: Christian Ehrhardt <christian.ehrhardt@canonical.com>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Message-id: 20220209111456.3328420-1-christian.ehrhardt@canonical.com
[Moved rseq to its alphabetically ordered position in the seccomp
allowlist.
--Stefan]
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
At the start, drop membership of all supplementary groups. This is
not required.
If we have membership of "root" supplementary group and when we switch
uid/gid using setresuid/setsgid, we still retain membership of existing
supplemntary groups. And that can allow some operations which are not
normally allowed.
For example, if root in guest creates a dir as follows.
$ mkdir -m 03777 test_dir
This sets SGID on dir as well as allows unprivileged users to write into
this dir.
And now as unprivileged user open file as follows.
$ su test
$ fd = open("test_dir/priviledge_id", O_RDWR|O_CREAT|O_EXCL, 02755);
This will create SGID set executable in test_dir/.
And that's a problem because now an unpriviliged user can execute it,
get egid=0 and get access to resources owned by "root" group. This is
privilege escalation.
Fixes: https://bugzilla.redhat.com/show_bug.cgi?id=2044863
Fixes: CVE-2022-0358
Reported-by: JIETAO XIAO <shawtao1125@gmail.com>
Suggested-by: Miklos Szeredi <mszeredi@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
Message-Id: <YfBGoriS38eBQrAb@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
dgilbert: Fixed missing {}'s style nit
Make the '--socket-group=' option fail if the group name is unknown:
./tools/virtiofsd/virtiofsd .... --socket-group=zaphod
vhost socket: unable to find group 'zaphod'
Reported-by: Xiaoling Gao <xiagao@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Message-Id: <20211014122554.34599-1-dgilbert@redhat.com>
Reviewed-by: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Use a helper to stop all the queues. Later in the patch series I am
planning to use this helper at one more place later in the patch series.
Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
Message-Id: <20210930153037.1194279-6-vgoyal@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
We have open coded logic to take locks and push element on virtqueue at
three places. Add a helper and use it everywhere. Code is easier to read and
less number of lines of code.
Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
Message-Id: <20210930153037.1194279-5-vgoyal@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
"struct virtio_fs_config" definition seems to be unused in fuse_virtio.c.
Remove it.
Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
Message-Id: <20210930153037.1194279-4-vgoyal@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Right now for xattr remapping, we support types of "prefix", "ok" or "bad".
Type "bad" returns -EPERM on setxattr and hides xattr in listxattr. For
getxattr, mapping code returns -EPERM but getxattr code converts it to -ENODATA.
I need a new semantics where if an xattr is unsupported, then
getxattr()/setxattr() return -ENOTSUP and listxattr() should hide the xattr.
This is needed to simulate that security.selinux is not supported by
virtiofs filesystem and in that case client falls back to some default
label specified by policy.
So add a new type "unsupported" which returns -ENOTSUP on getxattr() and
setxattr() and hides xattrs in listxattr().
For example, one can use following mapping rule to not support
security.selinux xattr and allow others.
"-o xattrmap=/unsupported/all/security.selinux/security.selinux//ok/all///"
Suggested-by: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
Message-Id: <YUt9qbmgAfCFfg5t@redhat.com>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Two minor fixes; one for performance, the other seccomp
on s390x.
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
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Merge remote-tracking branch 'remotes/dgilbert-gitlab/tags/pull-virtiofs-20210916' into staging
virtiofsd pull 2021-08-16
Two minor fixes; one for performance, the other seccomp
on s390x.
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
# gpg: Signature made Thu 16 Sep 2021 14:51:38 BST
# gpg: using RSA key 45F5C71B4A0CB7FB977A9FA90516331EBC5BFDE7
# gpg: Good signature from "Dr. David Alan Gilbert (RH2) <dgilbert@redhat.com>" [full]
# Primary key fingerprint: 45F5 C71B 4A0C B7FB 977A 9FA9 0516 331E BC5B FDE7
* remotes/dgilbert-gitlab/tags/pull-virtiofs-20210916:
virtiofsd: Reverse req_list before processing it
tools/virtiofsd: Add fstatfs64 syscall to the seccomp allowlist
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
With the thread pool disabled, we add the requests in the queue to a
GList, processing by iterating over there afterwards.
For adding them, we're using "g_list_prepend()", which is more
efficient but causes the requests to be processed in reverse order,
breaking the read-ahead and request-merging optimizations in the host
for sequential operations.
According to the documentation, if you need to process the request
in-order, using "g_list_prepend()" and then reversing the list with
"g_list_reverse()" is more efficient than using "g_list_append()", so
let's do it that way.
Testing on a spinning disk (to boost the increase of read-ahead and
request-merging) shows a 4x improvement on sequential write fio test:
Test:
fio --directory=/mnt/virtio-fs --filename=fio-file1 --runtime=20
--iodepth=16 --size=4G --direct=1 --blocksize=4K --ioengine libaio
--rw write --name seqwrite-libaio
Without "g_list_reverse()":
...
Jobs: 1 (f=1): [W(1)][100.0%][w=22.4MiB/s][w=5735 IOPS][eta 00m:00s]
seqwrite-libaio: (groupid=0, jobs=1): err= 0: pid=710: Tue Aug 24 12:58:16 2021
write: IOPS=5709, BW=22.3MiB/s (23.4MB/s)(446MiB/20002msec); 0 zone resets
...
With "g_list_reverse()":
...
Jobs: 1 (f=1): [W(1)][100.0%][w=84.0MiB/s][w=21.5k IOPS][eta 00m:00s]
seqwrite-libaio: (groupid=0, jobs=1): err= 0: pid=716: Tue Aug 24 13:00:15 2021
write: IOPS=21.3k, BW=83.1MiB/s (87.2MB/s)(1663MiB/20001msec); 0 zone resets
...
Signed-off-by: Sergio Lopez <slp@redhat.com>
Message-Id: <20210824131158.39970-1-slp@redhat.com>
Reviewed-by: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
The virtiofsd currently crashes on s390x when doing something like
this in the guest:
mkdir -p /mnt/myfs
mount -t virtiofs myfs /mnt/myfs
touch /mnt/myfs/foo.txt
stat -f /mnt/myfs/foo.txt
The problem is that the fstatfs64 syscall is called in this case
from the virtiofsd. We have to put it on the seccomp allowlist to
avoid that the daemon gets killed in this case.
Buglink: https://bugzilla.redhat.com/show_bug.cgi?id=2001728
Suggested-by: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Thomas Huth <thuth@redhat.com>
Message-Id: <20210914123214.181885-1-thuth@redhat.com>
Reviewed-by: Vivek Goyal <vgoyal@redhat.com>
Reviewed-by: Sergio Lopez <slp@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
fuse has an option FUSE_POSIX_ACL which needs to be opted in by fuse
server to enable posix acls. As of now we are not opting in for this,
so posix acls are disabled on virtiofs by default.
Add virtiofsd option "-o posix_acl/no_posix_acl" to let users enable/disable
posix acl support. By default it is disabled as of now due to performance
concerns with cache=none.
Currently even if file server has not opted in for FUSE_POSIX_ACL, user can
still query acl and set acl, and system.posix_acl_access and
system.posix_acl_default xattrs show up listxattr response.
Miklos said this is confusing. So he said lets block and filter
system.posix_acl_access and system.posix_acl_default xattrs in
getxattr/setxattr/listxattr if user has explicitly disabled
posix acls using -o no_posix_acl.
As of now continuing to keeping the existing behavior if user did not
specify any option to disable acl support due to concerns about backward
compatibility.
Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
Message-Id: <20210622150852.1507204-8-vgoyal@redhat.com>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
When posix access acls are set on a file, it can lead to adjusting file
permissions (mode) as well. If caller does not have CAP_FSETID and it
also does not have membership of owner group, this will lead to clearing
SGID bit in mode.
Current fuse code is written in such a way that it expects file server
to take care of chaning file mode (permission), if there is a need.
Right now, host kernel does not clear SGID bit because virtiofsd is
running as root and has CAP_FSETID. For host kernel to clear SGID,
virtiofsd need to switch to gid of caller in guest and also drop
CAP_FSETID (if caller did not have it to begin with).
If SGID needs to be cleared, client will set the flag
FUSE_SETXATTR_ACL_KILL_SGID in setxattr request. In that case server
should kill sgid.
Currently just switch to uid/gid of the caller and drop CAP_FSETID
and that should do it.
This should fix the xfstest generic/375 test case.
We don't have to switch uid for this to work. That could be one optimization
that pass a parameter to lo_change_cred() to only switch gid and not uid.
Also this will not work whenever (if ever) we support idmapped mounts. In
that case it is possible that uid/gid in request are 0/0 but still we
need to clear SGID. So we will have to pick a non-root sgid and switch
to that instead. That's an TODO item for future when idmapped mount
support is introduced.
This patch only adds the capability to switch creds and drop FSETID
when acl xattr is set. This does not take affect yet. It can take
affect when next patch adds the capability to enable posix_acl.
Reported-by: Luis Henriques <lhenriques@suse.de>
Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
Message-Id: <20210622150852.1507204-7-vgoyal@redhat.com>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
When parent directory has default acl and a file is created in that
directory, then umask is ignored and final file permissions are
determined using default acl instead. (man 2 umask).
Currently, fuse applies the umask and sends modified mode in create
request accordingly. fuse server can set FUSE_DONT_MASK and tell
fuse client to not apply umask and fuse server will take care of
it as needed.
With posix acls enabled, requirement will be that we want umask
to determine final file mode if parent directory does not have
default acl.
So if posix acls are enabled, opt in for FUSE_DONT_MASK. virtiofsd
will set umask of the thread doing file creation. And host kernel
should use that umask if parent directory does not have default
acls, otherwise umask does not take affect.
Miklos mentioned that we already call unshare(CLONE_FS) for
every thread. That means umask has now become property of per
thread and it should be ok to manipulate it in file creation path.
This patch only adds capability to change umask and restore it. It
does not enable it yet. Next few patches will add capability to enable it
based on if user enabled posix_acl or not.
This should fix fstest generic/099.
Reported-by: Luis Henriques <lhenriques@suse.de>
Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Message-Id: <20210622150852.1507204-6-vgoyal@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Patches in this series are going to make use of "umask" syscall.
So allow it.
Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-Id: <20210622150852.1507204-5-vgoyal@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Add the bits to enable support for setxattr_ext if fuse offers it. Do not
enable it by default yet. Let passthrough_ll opt-in. Enabling it by deafult
kind of automatically means that you are taking responsibility of clearing
SGID if ACL is set.
Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
Message-Id: <20210622150852.1507204-4-vgoyal@redhat.com>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Fixed up double def in fuse_common.h
getxattr/setxattr/removexattr/listxattr operations handle regualar
and non-regular files differently. For the case of non-regular files
we do fchdir(/proc/self/fd) and the xattr operation and then revert
back to original working directory. After this we are saving errno
and that's buggy because fchdir() will overwrite the errno.
FCHDIR_NOFAIL(lo->proc_self_fd);
ret = getxattr(procname, name, value, size);
FCHDIR_NOFAIL(lo->root.fd);
if (ret == -1)
saverr = errno
In above example, if getxattr() failed, we will still return 0 to caller
as errno must have been written by FCHDIR_NOFAIL(lo->root.fd) call.
Fix all such instances and capture "errno" early and save in "saverr"
variable.
Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
Message-Id: <20210622150852.1507204-3-vgoyal@redhat.com>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Reviewed-by: Greg Kurz <groug@kaod.org>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
With kernel header updates fuse_setxattr_in struct has grown in size.
But this new struct size only takes affect if user has opted in
for fuse feature FUSE_SETXATTR_EXT otherwise fuse continues to
send "fuse_setxattr_in" of older size. Older size is determined
by FUSE_COMPAT_SETXATTR_IN_SIZE.
Fix this. If we have not opted in for FUSE_SETXATTR_EXT, then
expect that we will get fuse_setxattr_in of size FUSE_COMPAT_SETXATTR_IN_SIZE
and not sizeof(struct fuse_sexattr_in).
Fixes: 278f064e45 ("Update Linux headers to 5.13-rc4")
Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
Message-Id: <20210622150852.1507204-2-vgoyal@redhat.com>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Reviewed-by: Greg Kurz <groug@kaod.org>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
A well behaved FUSE client uses FUSE_CREATE to create files. It isn't
supposed to pass O_CREAT along a FUSE_OPEN request, as documented in
the "fuse_lowlevel.h" header :
/**
* Open a file
*
* Open flags are available in fi->flags. The following rules
* apply.
*
* - Creation (O_CREAT, O_EXCL, O_NOCTTY) flags will be
* filtered out / handled by the kernel.
But if the client happens to do it anyway, the server ends up passing
this flag to open() without the mandatory mode_t 4th argument. Since
open() is a variadic function, glibc will happily pass whatever it
finds on the stack to the syscall. If this file is compiled with
-D_FORTIFY_SOURCE=2, glibc will even detect that and abort:
*** invalid openat64 call: O_CREAT or O_TMPFILE without mode ***: terminated
Specifying O_CREAT with FUSE_OPEN is a protocol violation. Check this
in do_open(), print out a message and return an error to the client,
EINVAL like we already do when fuse_mbuf_iter_advance() fails.
The FUSE filesystem doesn't currently support O_TMPFILE, but the very
same would happen if O_TMPFILE was passed in a FUSE_OPEN request. Check
that as well.
Signed-off-by: Greg Kurz <groug@kaod.org>
Message-Id: <20210624101809.48032-1-groug@kaod.org>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
The GDateTime APIs provided by GLib avoid portability pitfalls, such
as some platforms where 'struct timeval.tv_sec' field is still 'long'
instead of 'time_t'. When combined with automatic cleanup, GDateTime
often results in simpler code too.
Localtime is changed to UTC to avoid the need to grant extra seccomp
permissions for GLib's access of the timezone database.
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Message-Id: <20210611164319.67762-1-berrange@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
RSS program and Makefile to build it.
The bpftool used to generate '.h' file.
The data in that file may be loaded by libbpf.
EBPF compilation is not required for building qemu.
You can use Makefile if you need to regenerate rss.bpf.skeleton.h.
Signed-off-by: Yuri Benditovich <yuri.benditovich@daynix.com>
Signed-off-by: Andrew Melnychenko <andrew@daynix.com>
Signed-off-by: Jason Wang <jasowang@redhat.com>
Replaced a malloc() call and its respective free() with
GLib's g_try_malloc() and g_free() calls.
Signed-off-by: Mahmoud Mandour <ma.mandourr@gmail.com>
Message-Id: <20210314032324.45142-8-ma.mandourr@gmail.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Replaced a call to calloc() and its respective free() call
with GLib's g_try_new0() and g_free() calls.
Signed-off-by: Mahmoud Mandour <ma.mandourr@gmail.com>
Message-Id: <20210314032324.45142-7-ma.mandourr@gmail.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
