Any non-ambiguous shortening of a command name may be used in
lieu of the full command name. This facility should not be used
in scripting as new commands may be added in future that then
cause ambiguity.
Display the package version number
keyctl --version
This command prints the package version number and build date and
exits:
$ keyctl --version
keyctl from keyutils-1.5.3 (Built 2011-08-24)
Query subsystem capabilities
keyctl supports
keyctl supports --raw
keyctl supports <cap>
This command can list the available capabilities:
$ keyctl supports
have_capabilities=0
have_persistent_keyrings=1
have_dh_compute=1
have_public_key=1
produce a raw hex dump of the capabilities list:
$ keyctl supports --raw
ff0f
or query a specific capability:
$ keyctl supports pkey
echo $?
0
which exits 0 if the capability is supported, 1 if it isn't and 3
if the name is not recognised. The capabilities supported are:
capabilities
The kernel supports capability querying. If not, the
other capabilities will be queried as best libkeyutils can
manage.
persistent_keyrings
The kernel supports persistent keyrings.
dh_compute
The kernel supports Diffie-Hellman computation operations.
public_key
The kernel supports public key operations.
big_key_type
The kernel supports the big_key key type.
key_invalidate
The kernel supports the invalidate key operaiton.
restrict_keyring
The kernel supports the restrict_keyring operation.
move_key
The kernel supports the move key operation.
ns_keyring_name
Keyring names are segregated according to the user-
namespace in which the keyrings are created.
ns_key_tag
Keys can get tagged with namespace tags, allowing keys
with the same type and description, but different
namespaces to coexist in the same keyring. Tagging is
done automatically according to the key type.
Show actual key or keyring ID
keyctl id [<key>]
This command looks up the real ID of a key or keyring from the
identifier given, which is typically a symbolic ID such as "@s"
indicating the session keyring, but can also be a numeric ID or
"%type:desc" notation. If a special keyring is specified that
isn't created yet, an error will be given rather than causing
that keyring to be created.
Show process keyrings
keyctl show [-x] [<keyring>]
By default this command recursively shows what keyrings a process
is subscribed to and what keys and keyrings they contain. If a
keyring is specified then that keyring will be dumped instead.
If -x is specified then the keyring IDs will be dumped in hex
instead of decimal.
Add a key to a keyring
keyctl add [-x] <type> <desc> <data> <keyring>
keyctl padd [-x] <type> <desc> <keyring>
This command creates a key of the specified type and description;
instantiates it with the given data and attaches it to the
specified keyring. It then prints the new key's ID on stdout:
$ keyctl add user mykey stuff @u
26
The padd variant of the command reads the data from stdin rather
than taking it from the command line:
$ echo -n stuff | keyctl padd user mykey @u 26
If -x is given, then the data is hex-decoded with whitespace
being discarded.
Request a key
keyctl request <type> <desc> [<dest_keyring>]
keyctl request2 <type> <desc> <info> [<dest_keyring>]
keyctl prequest2 <type> <desc> [<dest_keyring>]
These three commands request the lookup of a key of the given
type and description. The process's keyrings will be searched,
and if a match is found the matching key's ID will be printed to
stdout; and if a destination keyring is given, the key will be
added to that keyring also.
If there is no key, the first command will simply return the
error ENOKEY and fail. The second and third commands will create
a partial key with the type and description, and call out to
/sbin/request-key with that key and the extra information
supplied. This will then attempt to instantiate the key in some
manner, such that a valid key is obtained.
The third command is like the second, except that the callout
information is read from stdin rather than being passed on the
command line.
If a valid key is obtained, the ID will be printed and the key
attached as if the original search had succeeded.
If there wasn't a valid key obtained, a temporary negative key
will be attached to the destination keyring if given and the
error "Requested key not available" will be given.
$ keyctl request2 user debug:hello wibble
23
$ echo -n wibble | keyctl prequest2 user debug:hello
23
$ keyctl request user debug:hello
23
Update a key
keyctl update [-x] <key> <data>
keyctl pupdate [-x] <key>
This command replaces the data attached to a key with a new set
of data. If the type of the key doesn't support update then error
"Operation not supported" will be returned.
$ keyctl update 23 zebra
The pupdate variant of the command reads the data from stdin
rather than taking it from the command line:
$ echo -n zebra | keyctl pupdate 23
$ echo 616263313233 | keyctl pupdate -x 23
If -x is given, then the data is hex-decoded with whitespace
being discarded.
Create a keyring
keyctl newring <name> <keyring>
This command creates a new keyring of the specified name and
attaches it to the specified keyring. The ID of the new keyring
will be printed to stdout if successful.
$ keyctl newring squelch @us
27
Revoke a key
keyctl revoke <key>
This command marks a key as being revoked. Any further operations
on that key (apart from unlinking it) will return error "Key has
been revoked".
$ keyctl revoke 26
$ keyctl describe 26
keyctl_describe: Key has been revoked
Clear a keyring
keyctl clear <keyring>
This command unlinks all the keys attached to the specified
keyring. Error "Not a directory" will be returned if the key
specified is not a keyring.
$ keyctl clear 27
Link a key to a keyring
keyctl link <key> <keyring>
This command makes a link from the key to the keyring if there's
enough capacity to do so. Error "Not a directory" will be
returned if the destination is not a keyring. Error "Permission
denied" will be returned if the key doesn't have link permission
or the keyring doesn't have write permission. Error "File table
overflow" will be returned if the keyring is full. Error
"Resource deadlock avoided" will be returned if an attempt was
made to introduce a recursive link.
$ keyctl link 23 27
$ keyctl link 27 27
keyctl_link: Resource deadlock avoided
Unlink a key from a keyring or the session keyring tree
keyctl unlink <key> [<keyring>]
If the keyring is specified, this command removes a link to the
key from the keyring. Error "Not a directory" will be returned if
the destination is not a keyring. Error "Permission denied" will
be returned if the keyring doesn't have write permission. Error
"No such file or directory" will be returned if the key is not
linked to by the keyring.
If the keyring is not specified, this command performs a depth-
first search of the session keyring tree and removes all the
links to the nominated key that it finds (and that it is
permitted to remove). It prints the number of successful unlinks
before exiting.
$ keyctl unlink 23 27
Move a key between keyrings.
keyctl move [-f] <key> <from_keyring> <to_keyring>
This command moves a key from one keyring to another, atomically
combining "keyctl unlink <key> <from_keyring>" and "keyctl link
<key> <to_keyring>".
If the "-f" flag is present, any matching key will be displaced
from "to_keyring"; if not present, the command will fail with the
error message "File exists" if the key would otherwise displace
another key from "to_keyring".
$ keyctl move 23 27 29
$ keyctl move -f 71 @u @s
Search a keyring
keyctl search <keyring> <type> <desc> [<dest_keyring>]
This command non-recursively searches a keyring for a key of a
particular type and description. If found, the ID of the key will
be printed on stdout and the key will be attached to the
destination keyring if present. Error "Requested key not
available" will be returned if the key is not found.
$ keyctl search @us user debug:hello
23
$ keyctl search @us user debug:bye
keyctl_search: Requested key not available
Restrict a keyring
keyctl restrict_keyring <keyring> [<type> [<restriction>]]
This command limits the linkage of keys to the given keyring
using a provided restriction scheme. The scheme is associated
with a given key type, with further details provided in the
restriction option string. Options typically contain a
restriction name possibly followed by key ids or other data
relevant to the restriction. If no restriction scheme is
provided, the keyring will reject all links.
$ keyctl restrict_keyring $1 asymmetric builtin_trusted
Read a key
keyctl read <key>
keyctl pipe <key>
keyctl print <key>
These commands read the payload of a key. "read" prints it on
stdout as a hex dump, "pipe" dumps the raw data to stdout and
"print" dumps it to stdout directly if it's entirely printable or
as a hexdump preceded by ":hex:" if not.
If the key type does not support reading of the payload, then
error "Operation not supported" will be returned.
$ keyctl read 26
1 bytes of data in key:
62
$ keyctl print 26
b
$ keyctl pipe 26
$
List a keyring
keyctl list <keyring>
keyctl rlist <keyring>
These commands list the contents of a key as a keyring. "list"
pretty prints the contents and "rlist" just produces a space-
separated list of key IDs.
No attempt is made to check that the specified keyring is a
keyring.
$ keyctl list @us
2 keys in keyring:
22: vrwsl---------- 4043 -1 keyring: _uid.4043
23: vrwsl---------- 4043 4043 user: debug:hello
$ keyctl rlist @us
22 23
Describe a key
keyctl describe <keyring>
keyctl rdescribe <keyring> [sep]
These commands fetch a description of a keyring. "describe"
pretty prints the description in the same fashion as the "list"
command; "rdescribe" prints the raw data returned from the
kernel.
$ keyctl describe @us
-5: vrwsl---------- 4043 -1 keyring: _uid_ses.4043
$ keyctl rdescribe @us
keyring;4043;-1;3f1f0000;_uid_ses.4043
The raw string is "<type>;<uid>;<gid>;<perms>;<description>",
where uid and gid are the decimal user and group IDs, perms is
the permissions mask in hex, type and description are the type
name and description strings (neither of which will contain
semicolons).
Change the access controls on a key
keyctl chown <key> <uid>
keyctl chgrp <key> <gid>
These two commands change the UID and GID associated with
evaluating a key's permissions mask. The UID also governs which
quota a key is taken out of.
The chown command is not currently supported; attempting it will
earn the error "Operation not supported" at best.
For non-superuser users, the GID may only be set to the process's
GID or a GID in the process's groups list. The superuser may set
any GID it likes.
$ sudo keyctl chown 27 0
keyctl_chown: Operation not supported
$ sudo keyctl chgrp 27 0
Set the permissions mask on a key
keyctl setperm <key> <mask>
This command changes the permission control mask on a key. The
mask may be specified as a hex number if it begins "0x", an octal
number if it begins "0" or a decimal number otherwise.
The hex numbers are a combination of:
Possessor UID GID Other Permission Granted
======== ======== ======== ======== ==================
01000000 00010000 00000100 00000001 View
02000000 00020000 00000200 00000002 Read
04000000 00040000 00000400 00000004 Write
08000000 00080000 00000800 00000008 Search
10000000 00100000 00001000 00000010 Link
20000000 00200000 00002000 00000020 Set Attribute
3f000000 003f0000 00003f00 0000003f All
View permits the type, description and other parameters of a key
to be viewed.
Read permits the payload (or keyring list) to be read if
supported by the type.
Write permits the payload (or keyring list) to be modified or
updated.
Search on a key permits it to be found when a keyring to which it
is linked is searched.
Link permits a key to be linked to a keyring.
Set Attribute permits a key to have its owner, group membership,
permissions mask and timeout changed.
$ keyctl setperm 27 0x1f1f1f00
Start a new session with fresh keyrings
keyctl session
keyctl session - [<prog> <arg1> <arg2> ...]
keyctl session <name> [<prog> <arg1> <arg2> ...]
These commands join or create a new keyring and then run a shell
or other program with that keyring as the session key.
The variation with no arguments just creates an anonymous session
keyring and attaches that as the session keyring; it then exec's
$SHELL.
The variation with a dash in place of a name creates an anonymous
session keyring and attaches that as the session keyring; it then
exec's the supplied command, or $SHELL if one isn't supplied.
The variation with a name supplied creates or joins the named
keyring and attaches that as the session keyring; it then exec's
the supplied command, or $SHELL if one isn't supplied.
$ keyctl rdescribe @s
keyring;4043;-1;3f1f0000;_uid_ses.4043
$ keyctl session
Joined session keyring: 28
$ keyctl rdescribe @s
keyring;4043;4043;3f1f0000;_ses.24082
$ keyctl session -
Joined session keyring: 29
$ keyctl rdescribe @s
keyring;4043;4043;3f1f0000;_ses.24139
$ keyctl session - keyctl rdescribe @s
Joined session keyring: 30
keyring;4043;4043;3f1f0000;_ses.24185
$ keyctl session fish
Joined session keyring: 34
$ keyctl rdescribe @s
keyring;4043;4043;3f1f0000;fish
$ keyctl session fish keyctl rdesc @s
Joined session keyring: 35
keyring;4043;4043;3f1f0000;fish
Instantiate a key
keyctl instantiate [-x] <key> <data> <keyring>
keyctl pinstantiate [-x] <key> <keyring>
keyctl negate <key> <timeout> <keyring>
keyctl reject <key> <timeout> <error> <keyring>
These commands are used to attach data to a partially set up key
(as created by the kernel and passed to /sbin/request-key).
"instantiate" marks a key as being valid and attaches the data as
the payload. "negate" and "reject" mark a key as invalid and
sets a timeout on it so that it'll go away after a while. This
prevents a lot of quickly sequential requests from slowing the
system down overmuch when they all fail, as all subsequent
requests will then fail with error "Requested key not found" (if
negated) or the specified error (if rejected) until the negative
key has expired.
Reject's error argument can either be a UNIX error number or one
of 'rejected', 'expired' or 'revoked'.
The newly instantiated key will be attached to the specified
keyring.
These commands may only be run from the program run by
request-key - a special authorisation key is set up by the kernel
and attached to the request-key's session keyring. This special
key is revoked once the key to which it refers has been
instantiated one way or another.
$ keyctl instantiate $1 "Debug $3" $4
$ keyctl negate $1 30 $4
$ keyctl reject $1 30 64 $4
The pinstantiate variant of the command reads the data from stdin
rather than taking it from the command line:
$ echo -n "Debug $3" | keyctl pinstantiate $1 $4
If -x is given, then the data is hex-decoded with whitespace
being discarded:
$ echo 01 02 03 04 | keyctl pinstantiate -x $1 $4
Set the expiry time on a key
keyctl timeout <key> <timeout>
This command is used to set the timeout on a key, or clear an
existing timeout if the value specified is zero. The timeout is
given as a number of seconds into the future.
$ keyctl timeout $1 45
Retrieve a key's security context
keyctl security <key>
This command is used to retrieve a key's LSM security context.
The label is printed on stdout.
$ keyctl security @s
unconfined_u:unconfined_r:unconfined_t:s0-s0:c0.c1023
Give the parent process a new session keyring
keyctl new_session [<name>]
This command is used to give the invoking process (typically a
shell) a new session keyring, discarding its old session keyring.
If a name is given, the keyring is given that name, otherwise it
will be given a name of "_ses" and will not be manually joinable.
$ keyctl session foo
Joined session keyring: 723488146
$ keyctl show
Session Keyring
-3 --alswrv 0 0 keyring: foo
$ keyctl new_session
490511412
$ keyctl show
Session Keyring
-3 --alswrv 0 0 keyring: _ses
Note that this affects the parent of the process that invokes the
system call, and so may only affect processes with matching
credentials. Furthermore, the change does not take effect till
the parent process next transitions from kernel space to user
space - typically when the wait() system call returns.
Remove dead keys from the session keyring tree
keyctl reap
This command performs a depth-first search of the caller's
session keyring tree and attempts to unlink any key that it finds
that is inaccessible due to expiry, revocation, rejection or
negation. It does not attempt to remove live keys that are
unavailable simply due to a lack of granted permission.
A key that is designated reapable will only be removed from a
keyring if the caller has Write permission on that keyring, and
only keyrings that grant Search permission to the caller will be
searched.
The command prints the number of keys reaped before it exits. If
the -v flag is passed then the reaped keys are listed as they're
being reaped, together with the success or failure of the unlink.
Remove matching keys from the session keyring tree
keyctl purge <type>
keyctl purge [-i] [-p] <type> <desc>
keyctl purge -s <type> <desc>
These commands perform a depth-first search to find matching keys
in the caller's session keyring tree and attempts to unlink them.
The number of keys successfully unlinked is printed at the end.
The keyrings must grant Read and View permission to the caller to
be searched, and the keys to be removed must also grant View
permission. Keys can only be removed from keyrings that grant
Write permission.
The first variant purges all keys of the specified type.
The second variant purges all keys of the specified type that
also match the given description literally. The -i flag allows a
case-independent match and the -p flag allows a prefix match.
The third variant purges all keys of the specified type and
matching description using the key type's comparator in the
kernel to match the description. This permits the key type to
match a key with a variety of descriptions.
Get persistent keyring
keyctl get_persistent <keyring> [<uid>]
This command gets the persistent keyring for either the current
UID or the specified UID and attaches it to the nominated
keyring. The persistent keyring's ID will be printed on stdout.
The kernel will create the keyring if it doesn't exist and every
time this command is called, will reset the expiration timeout on
the keyring to the value in:
/proc/sys/kernel/keys/persistent_keyring_expiry
(by default three days). Should the timeout be reached, the
persistent keyring will be removed and everything it pins can
then be garbage collected.
If a UID other than the process's real or effective UIDs is
specified, then an error will be given if the process does not
have the CAP_SETUID capability.
Compute a Diffie-Hellman shared secret or public key
keyctl dh_compute <private> <prime> <base>
This command computes either a Diffie-Hellman shared secret or
the public key corresponding to the provided private key using
the payloads of three keys. The computation is:
base ^ private (mod prime)
The three inputs must be user keys with read permission. If the
provided base key contains the shared generator value, the public
key will be computed. If the provided base key contains the
remote public key value, the shared secret will be computed.
The result is printed to stdout as a hex dump.
$ keyctl dh_compute $1 $2 $3
8 bytes of data in result:
00010203 04050607
Compute a Diffie-Hellman shared secret and derive key material
keyctl dh_compute_kdf <private> <prime> <base> <output_length>
<hash_type>
This command computes a Diffie-Hellman shared secret and derives
key material from the shared secret using a key derivation
function (KDF). The shared secret is derived as outlined above
and is input to the KDF using the specified hash type. The hash
type must point to a hash name known to the kernel crypto API.
The operation derives key material of the length specified by the
caller.
The operation is compliant to the specification of SP800-56A.
The result is printed to stdout as hex dump.
Compute a Diffie-Hellman shared secret and apply KDF with other input
keyctl dh_compute_kdf_oi [-x] <private> <prime> <base>
<output_length> <hash_type>
This command is identical to the command dh_compute_kdf to
generate a Diffie-Hellman shared secret followed by a key
derivation operation. This command allows the caller to provide
the other input data (OI data) compliant to SP800-56A via stdin.
If -x is given, then the data passed to stdin is hex-decoded with
whitespace being discarded.
Perform public-key operations with an asymmetric key
keyctl pkey_query <key> <pass> [k=v]*
keyctl pkey_encrypt <key> <pass> <datafile> [k=v]* > <encfile>
keyctl pkey_decrypt <key> <pass> <encfile> [k=v]* > <datafile>
keyctl pkey_sign <key> <pass> <datafile> [k=v]* > <sigfile>
keyctl pkey_verify <key> <pass> <datafile> <sigfile> [k=v]*
These commands query an asymmetric key, encrypt data with it,
decrypt the encrypted data, generate a signature over some data
and verify that signature. For encrypt, decrypt and sign, the
resulting data is written to stdout; verify reads the data and
the signature files and compares them.
[!] NOTE that the data is of very limited capacity, with no more
bits than the size of the key. For signatures, the caller is
expected to digest the actual data and pass in the result of the
digest as the datafile. The name of the digest should be
specified on the end of the command line as "hash=<name>".
The key ID indicates the key to use; pass is a placeholder for
future password provision and should be "0" for the moment;
datafile is the unencrypted data to be encrypted, signed or to
have its signature checked; encfile is a file containing
encrypted data; and sigfile is a file containing a signature.
A list of parameters in "key[=val]" form can be included on the
end of the command line. These specify things like the digest
algorithm used ("hash=<name>") or the encoding form
("enc=<type>").
k=`keyctl padd asymmetric "" @s <key.pkcs8.der`
keyctl pkey_query $k 0 enc=pkcs1 hash=sha256
keyctl pkey_encrypt $k 0 foo.hash enc=pkcs1 >foo.enc
keyctl pkey_decrypt $k 0 foo.enc enc=pkcs1 >foo.hash
keyctl pkey_sign $k 0 foo.hash enc=pkcs1 hash=sha256 >foo.sig
keyctl pkey_verify $k 0 foo.hash foo.sig enc=pkcs1 hash=sha256
See asymmetric-key(7) for more information.
Change notifications
keyctl watch [-f<filters>] <key>
keyctl watch_session [-f <filters>] [-n <name>] \
<notifylog> <gclog> <fd> <prog> [<arg1> <arg2>
...] keyctl watch_add <fd> <key>
keyctl watch_rm <fd> <key>
The watch command watches a single key, printing notifications to
stdout until the key is destroyed. Filters can be employed to
cut down the events that will be delivered. The filter string is
a series of letters, each one of which enables a particular event
subtype:
i - The key has been instantiated
p - The key has been updated
l - A link has been added to a keyring
n - A link has been removed from a keyring
c - A keyring has been cleared
r - A key has been revoked
v - A key has been invalidated
s - A key has had its attributes changed
The output of the command looks like:
<keyid> <event> [<aux>]
Where keyid is the primary subject of the notification, op is the
event and aux is the secondary key if there is one (such as link
where the primary key is the keyring secondary key is the key
being linked in to it). For example:
255913279 link 340681059
255913279 clr
An additional notication is generated when a key being watched is
garbage collected, e.g.:
255913279 gc
The watch_session command creates a new session keyring, with
name name if given, watches it for notifications and runs program
prog with it. The program is given the specified arguments.
A second process is forked off to monitor the notifications. The
output from that is directed to the files notifylog for most
notifications and gclog for key removal notifications (which are
asynchronous and may be deferred).
The watch_queue(7) device is exported to the program attached to
fd number fd. This can be passed by the other two commands.
The watch_add command adds a watch on key to the watch_queue
attached to fd as exported by watch_session and the watch_rm
caommand removes it. A watch_queue can handle multiple keys and
even non-keys sources as well.
