This document is for a development version of Ceph.
ceph-authtool – ceph keyring manipulation tool¶
ceph-authtool is a utility to create, view, and modify a Ceph keyring
file. A keyring file stores one or more Ceph authentication keys and
possibly an associated capability specification. Each key is
associated with an entity name, of the form
WARNING Ceph provides authentication and protection against man-in-the-middle attacks once secret keys are in place. However, data over the wire is not encrypted, which may include the messages used to configure said keys. The system is primarily intended to be used in trusted environments.
will list all keys and capabilities present in the keyring
will print an encoded key for the specified entityname. This is suitable for the
mount -o secret=argument
will create a new keyring, overwriting any existing keyringfile
will generate a new secret key for the specified entityname
will generate a new secret key for the specified entityname, without altering the keyringfile, printing the secret to stdout
will import the content of a given keyring to the keyringfile
specify entityname to operate on
will add an encoded key to the keyring
will set the capability for given subsystem
The subsystem is the name of a Ceph subsystem:
The capability is a string describing what the given user is allowed
to do. This takes the form of a comma separated list of allow
clauses with a permission specifier containing one or more of rwx for
read, write, and execute permission. The
allow * grants full
superuser permissions for the given subsystem.
# can read, write, and execute objects osd = "allow rwx" # can access mds server mds = "allow" # can modify cluster state (i.e., is a server daemon) mon = "allow rwx"
A librados user restricted to a single pool might look like:
mon = "allow r" osd = "allow rw pool foo"
A client using rbd with read access to one pool and read/write access to another:
mon = "allow r" osd = "allow class-read object_prefix rbd_children, allow pool templates r class-read, allow pool vms rwx"
A client mounting the file system with minimal permissions would need caps like:
mds = "allow" osd = "allow rw pool data" mon = "allow r"
In general, an osd capability follows the grammar:
osdcap := grant[,grant...] grant := allow (match capspec | capspec match) match := [ pool[=]<poolname> | object_prefix <prefix> | namespace[=]<rados-namespace> | tag <application-name> <key>=<value> ] capspec := * | [r][w][x] [class-read] [class-write]
The capspec determines what kind of operations the entity can perform:
r = read access to objects w = write access to objects x = can call any class method (same as class-read class-write) class-read = can call class methods that are reads class-write = can call class methods that are writes * or "all" = equivalent to rwx, plus the ability to run osd admin commands, i.e. ceph osd tell ...
The match criteria restrict a grant based on the pool being accessed. Grants are additive if the client fulfills the match condition. For example, if a client has the osd capabilities: “allow r object_prefix prefix, allow w pool foo, allow x pool bar”, then it has rw access to pool foo, rx access to pool bar, and r access to objects whose names begin with ‘prefix’ in any pool.
Caps file format¶
The caps file format consists of zero or more key/value pairs, one per
line. The key and value are separated by an
=, and the value must
be quoted (with
") if it contains any whitespace. The key
is the name of the Ceph subsystem (
mon), and the
value is the capability string (see above).
To create a new keyring containing a key for client.foo with a 0644 file mode:
ceph-authtool -C -n client.foo --gen-key keyring --mode 0644
To associate some capabilities with the key (namely, the ability to mount a Ceph file system):
ceph-authtool -n client.foo --cap mds 'allow' --cap osd 'allow rw pool=data' --cap mon 'allow r' keyring
To display the contents of the keyring:
ceph-authtool -l keyring
When mounting a Ceph file system, you can grab the appropriately encoded secret key with:
mount -t ceph serverhost:/ mountpoint -o name=foo,secret=`ceph-authtool -p -n client.foo keyring`
ceph-authtool is part of Ceph, a massively scalable, open-source, distributed storage system. Please refer to the Ceph documentation at https://docs.ceph.com for more information.