Allow smbd to load libcephfs proxy conditionally #2555
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anoopcs9
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For the time being, until the official fix[1] is available with standard selinux-policy packages, compile and insert a local SELinux policy to allow smbd to connect via unix stream sockets for proper fucntioning of libcephfs proxy. Refer comments from [2] for more details. [1] fedora-selinux/selinux-policy#2555 [2] samba-in-kubernetes#128 Signed-off-by: Anoop C S <anoopcs@cryptolab.net>
The design for libcephfs proxy[1] was accepted sometime back with the
corresponding implementation subsequently merged[2] into upstream Ceph.
This additional way to integrate CephFS with Samba is comprised of two
components. The daemon i.e, libcephfsd is responsible for creating the
unix domain socket as a starting point of communication. On the other
side proxy library, which is designed[3] to be loaded within smbd,
connects to the already created socket and thereby communicates with
the daemon.
During the development and testing stages we happened to notice some AVC
denial messages in the audit logs:
type=AVC msg=audit(1738236295.070:1470): avc: denied { write } for pid=41822
comm="smbd[192.168.12" name="libcephfsd.sock" dev="tmpfs" ino=1908
scontext=system_u:system_r:smbd_t:s0 tcontext=unconfined_u:object_r:var_run_t:s0
tclass=sock_file permissive=1
type=AVC msg=audit(1738236295.070:1470): avc: denied { connectto } for pid=41822
comm="smbd[192.168.12" path="/run/libcephfsd.sock"
scontext=system_u:system_r:smbd_t:s0 tcontext=unconfined_u:unconfined_r:unconfined_t:s0-s0:c0.c1023
tclass=unix_stream_socket permissive=1
Therefore we propose a new boolean - samba_load_libcephfs_proxy, off by
default, to contain the necessary allow rules for smbd_t to operate in a
proxy mode using libcephfs.
[1] https://docs.ceph.com/en/latest/dev/libcephfs_proxy/
[2] ceph/ceph#58376
[3] https://gitlab.com/samba-team/samba/-/merge_requests/3792
Signed-off-by: Anoop C S <anoopcs@cryptolab.net>
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anoopcs9
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Feb 5, 2025
For the time being, until the official fix[1] is available with standard selinux-policy packages, compile and insert a local SELinux policy to allow smbd to connect via unix stream sockets for proper fucntioning of libcephfs proxy. Refer comments from [2] for more details. [1] fedora-selinux/selinux-policy#2555 [2] #128 Signed-off-by: Anoop C S <anoopcs@cryptolab.net>
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@zpytela I hope rpm-build:fedora-41-x86_64 job failure is expected. |
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@zpytela Can you please take a look at this change? |
zpytela
reviewed
Mar 3, 2025
| optional_policy(` | ||
| tunable_policy(`samba_load_libcephfs_proxy',` | ||
| unconfined_stream_connect(smbd_t) | ||
| rw_sock_files_pattern(smbd_t, var_run_t, var_run_t) |
There was a problem hiding this comment.
Which service creates and/or works with files with the var_run_t type? A private type should be used in cases of allowing write access.
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The design for libcephfs proxy was accepted sometime back with the corresponding implementation subsequently merged into upstream Ceph. This additional way to integrate CephFS with Samba is comprised of two components. The daemon i.e, libcephfsd is responsible for creating the unix domain socket as a starting point of communication. On the other side proxy library, which is designed to be loaded within smbd, connects to the already created socket and thereby communicates with the daemon.
During the development and testing stages we happened to notice some AVC denial messages in the audit logs:
Therefore we propose a new boolean - samba_load_libcephfs_proxy, off by default, to contain the necessary allow rules for smbd_t to operate in a proxy mode using libcephfs.