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149 lines
4.9 KiB
ReStructuredText
149 lines
4.9 KiB
ReStructuredText
================================
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CephFS Client Capabilities
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================================
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Use Ceph authentication capabilities to restrict your filesystem clients
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to the lowest possible level of authority needed.
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.. note::
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Path restriction and layout modification restriction are new features
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in the Jewel release of Ceph.
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Path restriction
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================
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By default, clients are not restricted in what paths they are allowed to mount.
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Further, when clients mount a subdirectory, e.g., /home/user, the MDS does not
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by default verify that subsequent operations
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are ‘locked’ within that directory.
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To restrict clients to only mount and work within a certain directory, use
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path-based MDS authentication capabilities.
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Syntax
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------
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To grant rw access to the specified directory only, we mention the specified
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directory while creating key for a client using the following syntax. ::
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ceph fs authorize *filesystem_name* client.*client_name* /*specified_directory* rw
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for example, to restrict client ``foo`` to writing only in the ``bar`` directory of filesystem ``cephfs``, use ::
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ceph fs authorize cephfs client.foo / r /bar rw
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results in:
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client.foo
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key: *key*
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caps: [mds] allow r, allow rw path=/bar
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caps: [mon] allow r
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caps: [osd] allow rw tag cephfs data=cephfs_a
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To completely restrict the client to the ``bar`` directory, omit the
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root directory ::
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ceph fs authorize cephfs client.foo /bar rw
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Note that if a client's read access is restricted to a path, they will only
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be able to mount the filesystem when specifying a readable path in the
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mount command (see below).
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Supplying ``all`` or ``*`` as the filesystem name will grant access to every
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file system. Note that it is usually necessary to quote ``*`` to protect it from
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the shell.
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See `User Management - Add a User to a Keyring`_. for additional details on user management
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To restrict a client to the specified sub-directory only, we mention the specified
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directory while mounting using the following syntax. ::
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./ceph-fuse -n client.*client_name* *mount_path* -r *directory_to_be_mounted*
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for example, to restrict client ``foo`` to ``mnt/bar`` directory, we will use. ::
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./ceph-fuse -n client.foo mnt -r /bar
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Free space reporting
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--------------------
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By default, when a client is mounting a sub-directory, the used space (``df``)
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will be calculated from the quota on that sub-directory, rather than reporting
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the overall amount of space used on the cluster.
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If you would like the client to report the overall usage of the filesystem,
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and not just the quota usage on the sub-directory mounted, then set the
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following config option on the client:
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::
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client quota df = false
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If quotas are not enabled, or no quota is set on the sub-directory mounted,
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then the overall usage of the filesystem will be reported irrespective of
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the value of this setting.
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Layout and Quota restriction (the 'p' flag)
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===========================================
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To set layouts or quotas, clients require the 'p' flag in addition to 'rw'.
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This restricts all the attributes that are set by special extended attributes
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with a "ceph." prefix, as well as restricting other means of setting
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these fields (such as openc operations with layouts).
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For example, in the following snippet client.0 can modify layouts and quotas
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on the filesystem cephfs_a, but client.1 cannot.
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::
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client.0
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key: AQAz7EVWygILFRAAdIcuJ12opU/JKyfFmxhuaw==
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caps: [mds] allow rwp
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caps: [mon] allow r
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caps: [osd] allow rw tag cephfs data=cephfs_a
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client.1
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key: AQAz7EVWygILFRAAdIcuJ12opU/JKyfFmxhuaw==
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caps: [mds] allow rw
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caps: [mon] allow r
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caps: [osd] allow rw tag cephfs data=cephfs_a
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Snapshot restriction (the 's' flag)
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===========================================
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To create or delete snapshots, clients require the 's' flag in addition to 'rw'.
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Note that when capability string also contains the 'p' flag, the 's' flag must
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appear after it (all flags except 'rw' must be specified in alphabetical order).
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For example, in the following snippet client.0 can create or delete snapshots
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in the ``bar`` directory of filesystem ``cephfs_a``.
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::
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client.0
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key: AQAz7EVWygILFRAAdIcuJ12opU/JKyfFmxhuaw==
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caps: [mds] allow rw, allow rws path=/bar
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caps: [mon] allow r
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caps: [osd] allow rw tag cephfs data=cephfs_a
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.. _User Management - Add a User to a Keyring: ../../rados/operations/user-management/#add-a-user-to-a-keyring
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Network restriction
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===================
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::
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client.foo
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key: *key*
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caps: [mds] allow r network 10.0.0.0/8, allow rw path=/bar network 10.0.0.0/8
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caps: [mon] allow r network 10.0.0.0/8
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caps: [osd] allow rw tag cephfs data=cephfs_a network 10.0.0.0/8
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The optional ``{network/prefix}`` is a standard network name and
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prefix length in CIDR notation (e.g., ``10.3.0.0/16``). If present,
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the use of this capability is restricted to clients connecting from
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this network.
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