# SPDX-License-Identifier: GPL-2.0-only
#
# Key management configuration
#
config KEYS
bool "Enable access key retention support"
select ASSOCIATIVE_ARRAY
help
This option provides support for retaining authentication tokens and
access keys in the kernel.
It also includes provision of methods by which such keys might be
associated with a process so that network filesystems, encryption
support and the like can find them.
Furthermore, a special type of key is available that acts as keyring:
a searchable sequence of keys. Each process is equipped with access
to five standard keyrings: UID-specific, GID-specific, session,
process and thread.
If you are unsure as to whether this is required, answer N.
config KEYS_REQUEST_CACHE
bool "Enable temporary caching of the last request_key() result"
depends on KEYS
help
This option causes the result of the last successful request_key()
call that didn't upcall to the kernel to be cached temporarily in the
task_struct. The cache is cleared by exit and just prior to the
resumption of userspace.
This allows the key used for multiple step processes where each step
wants to request a key that is likely the same as the one requested
by the last step to save on the searching.
An example of such a process is a pathwalk through a network
filesystem in which each method needs to request an authentication
key. Pathwalk will call multiple methods for each dentry traversed
(permission, d_revalidate, lookup, getxattr, getacl, ...).
config PERSISTENT_KEYRINGS
bool "Enable register of persistent per-UID keyrings"
depends on KEYS
help
This option provides a register of persistent per-UID keyrings,
primarily aimed at Kerberos key storage. The keyrings are persistent
in the sense that they stay around after all processes of that UID
have exited, not that they survive the machine being rebooted.
A particular keyring may be accessed by either the user whose keyring
it is or by a process with administrative privileges. The active
LSMs gets to rule on which admin-level processes get to access the
cache.
Keyrings are created and added into the register upon demand and get
removed if they expire (a default timeout is set upon creation).
config BIG_KEYS
bool "Large payload keys"
depends on KEYS
depends on TMPFS
depends on CRYPTO_LIB_CHACHA20POLY1305 = y
help
This option provides support for holding large keys within the kernel
(for example Kerberos ticket caches). The data may be stored out to
swapspace by tmpfs.
If you are unsure as to whether this is required, answer N.
config TRUSTED_KEYS
tristate "TRUSTED KEYS"
depends on KEYS
help
This option provides support for creating, sealing, and unsealing
keys in the kernel. Trusted keys are random number symmetric keys,
generated and sealed by a trust source selected at kernel boot-time.
Userspace will only ever see encrypted blobs.
If you are unsure as to whether this is required, answer N.
if TRUSTED_KEYS
source "security/keys/trusted-keys/Kconfig"
endif
config ENCRYPTED_KEYS
tristate "ENCRYPTED KEYS"
depends on KEYS
select CRYPTO
select CRYPTO_HMAC
select CRYPTO_AES
select CRYPTO_CBC
select CRYPTO_SHA256
select CRYPTO_RNG
help
This option provides support for create/encrypting/decrypting keys
in the kernel. Encrypted keys are instantiated using kernel
generated random numbers or provided decrypted data, and are
encrypted/decrypted with a 'master' symmetric key. The 'master'
key can be either a trusted-key or user-key type. Only encrypted
blobs are ever output to Userspace.
If you are unsure as to whether this is required, answer N.
config USER_DECRYPTED_DATA
bool "Allow encrypted keys with user decrypted data"
depends on ENCRYPTED_KEYS
help
This option provides support for instantiating encrypted keys using
user-provided decrypted data. The decrypted data must be hex-ascii
encoded.
If you are unsure as to whether this is required, answer N.
config KEY_DH_OPERATIONS
bool "Diffie-Hellman operations on retained keys"
depends on KEYS
select CRYPTO
select CRYPTO_KDF800108_CTR
select CRYPTO_DH
help
This option provides support for calculating Diffie-Hellman
public keys and shared secrets using values stored as keys
in the kernel.
If you are unsure as to whether this is required, answer N.
config KEY_NOTIFICATIONS
bool "Provide key/keyring change notifications"
depends on KEYS && WATCH_QUEUE
help
This option provides support for getting change notifications
on keys and keyrings on which the caller has View permission.
This makes use of pipes to handle the notification buffer and
provides KEYCTL_WATCH_KEY to enable/disable watches.
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