# SPDX-License-Identifier: GPL-2.0-only
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#
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# Key management configuration
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#
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config KEYS
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bool "Enable access key retention support"
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select ASSOCIATIVE_ARRAY
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help
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This option provides support for retaining authentication tokens and
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access keys in the kernel.
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It also includes provision of methods by which such keys might be
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associated with a process so that network filesystems, encryption
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support and the like can find them.
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Furthermore, a special type of key is available that acts as keyring:
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a searchable sequence of keys. Each process is equipped with access
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to five standard keyrings: UID-specific, GID-specific, session,
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process and thread.
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If you are unsure as to whether this is required, answer N.
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config KEYS_REQUEST_CACHE
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bool "Enable temporary caching of the last request_key() result"
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depends on KEYS
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help
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This option causes the result of the last successful request_key()
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call that didn't upcall to the kernel to be cached temporarily in the
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task_struct. The cache is cleared by exit and just prior to the
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resumption of userspace.
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This allows the key used for multiple step processes where each step
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wants to request a key that is likely the same as the one requested
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by the last step to save on the searching.
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An example of such a process is a pathwalk through a network
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filesystem in which each method needs to request an authentication
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key. Pathwalk will call multiple methods for each dentry traversed
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(permission, d_revalidate, lookup, getxattr, getacl, ...).
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config PERSISTENT_KEYRINGS
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bool "Enable register of persistent per-UID keyrings"
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depends on KEYS
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help
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This option provides a register of persistent per-UID keyrings,
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primarily aimed at Kerberos key storage. The keyrings are persistent
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in the sense that they stay around after all processes of that UID
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have exited, not that they survive the machine being rebooted.
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A particular keyring may be accessed by either the user whose keyring
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it is or by a process with administrative privileges. The active
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LSMs gets to rule on which admin-level processes get to access the
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cache.
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Keyrings are created and added into the register upon demand and get
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removed if they expire (a default timeout is set upon creation).
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config BIG_KEYS
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bool "Large payload keys"
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depends on KEYS
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depends on TMPFS
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depends on CRYPTO_LIB_CHACHA20POLY1305 = y
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help
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This option provides support for holding large keys within the kernel
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(for example Kerberos ticket caches). The data may be stored out to
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swapspace by tmpfs.
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If you are unsure as to whether this is required, answer N.
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config TRUSTED_KEYS
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tristate "TRUSTED KEYS"
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depends on KEYS && TCG_TPM
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select CRYPTO
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select CRYPTO_HMAC
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select CRYPTO_SHA1
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select CRYPTO_HASH_INFO
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help
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This option provides support for creating, sealing, and unsealing
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keys in the kernel. Trusted keys are random number symmetric keys,
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generated and RSA-sealed by the TPM. The TPM only unseals the keys,
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if the boot PCRs and other criteria match. Userspace will only ever
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see encrypted blobs.
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If you are unsure as to whether this is required, answer N.
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config ENCRYPTED_KEYS
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tristate "ENCRYPTED KEYS"
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depends on KEYS
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select CRYPTO
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select CRYPTO_HMAC
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select CRYPTO_AES
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select CRYPTO_CBC
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select CRYPTO_SHA256
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select CRYPTO_RNG
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help
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This option provides support for create/encrypting/decrypting keys
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in the kernel. Encrypted keys are kernel generated random numbers,
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which are encrypted/decrypted with a 'master' symmetric key. The
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'master' key can be either a trusted-key or user-key type.
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Userspace only ever sees/stores encrypted blobs.
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If you are unsure as to whether this is required, answer N.
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config KEY_DH_OPERATIONS
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bool "Diffie-Hellman operations on retained keys"
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depends on KEYS
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select CRYPTO
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select CRYPTO_HASH
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select CRYPTO_DH
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help
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This option provides support for calculating Diffie-Hellman
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public keys and shared secrets using values stored as keys
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in the kernel.
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If you are unsure as to whether this is required, answer N.
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config KEY_NOTIFICATIONS
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bool "Provide key/keyring change notifications"
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depends on KEYS && WATCH_QUEUE
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help
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This option provides support for getting change notifications
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on keys and keyrings on which the caller has View permission.
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This makes use of pipes to handle the notification buffer and
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provides KEYCTL_WATCH_KEY to enable/disable watches.
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