add_key()
asks the kernel to create or update a key of the given
type
and
description,
instantiate it with the
payload
of length
plen,
and to attach it to the nominated
keyring
and to return its serial number.
The key type may reject the data if it's in the wrong format or in some other
way invalid.
If the destination
keyring
already contains a key that matches the specified
type and description
then, if the key type supports it, that key will be updated rather than a new
key being created; if not, a new key will be created and it will displace the
link to the extant key from the keyring.
The destination
keyring
serial number may be that of a valid keyring to which the caller has write
permission, or it may be a special keyring ID:
KEY_SPEC_THREAD_KEYRING
This specifies the caller's thread-specific keyring.
KEY_SPEC_PROCESS_KEYRING
This specifies the caller's process-specific keyring.
KEY_SPEC_SESSION_KEYRING
This specifies the caller's session-specific keyring.
KEY_SPEC_USER_KEYRING
This specifies the caller's UID-specific keyring.
KEY_SPEC_USER_SESSION_KEYRING
This specifies the caller's UID-session keyring.
KEY TYPES
There are a number of key types available in the core key management code, and
these can be specified to this function:
``user''
Keys of the user-defined key type may contain a blob of arbitrary data, and the
description
may be any valid string, though it is preferred that the description be
prefixed with a string representing the service to which the key is of interest
and a colon (for instance
``afs:mykey'').
The
payload
may be empty or
NULL
for keys of this type.
``keyring''
Keyrings are special key types that may contain links to sequences of other
keys of any type. If this interface is used to create a keyring, then a
NULLpayload
should be specified, and
plen
should be zero.
RETURN VALUE
On success
add_key()
returns the serial number of the key it created or updated.
On error, the value
-1
will be returned and errno will have been set to an appropriate error.
ERRORS
ENOKEY
The keyring doesn't exist.
EKEYEXPIRED
The keyring has expired.
EKEYREVOKED
The keyring has been revoked.
EINVAL
The payload data was invalid.
ENOMEM
Insufficient memory to create a key.
EDQUOT
The key quota for this user would be exceeded by creating this key or linking
it to the keyring.
EACCES
The keyring wasn't available for modification by the user.
LINKING
Although this is a Linux system call, it is not present in
libc
but can be found rather in
libkeyutils.
When linking,
-lkeyutils
should be specified to the linker.
