LXR linux/security/keys/Kconfig

   1# SPDX-License-Identifier: GPL-2.0-only
   2#
   3# Key management configuration
   4#
   5
   6config KEYS
   7        bool "Enable access key retention support"
   8        select ASSOCIATIVE_ARRAY
   9        help
  10          This option provides support for retaining authentication tokens and
  11          access keys in the kernel.
  12
  13          It also includes provision of methods by which such keys might be
  14          associated with a process so that network filesystems, encryption
  15          support and the like can find them.
  16
  17          Furthermore, a special type of key is available that acts as keyring:
  18          a searchable sequence of keys. Each process is equipped with access
  19          to five standard keyrings: UID-specific, GID-specific, session,
  20          process and thread.
  21
  22          If you are unsure as to whether this is required, answer N.
  23
  24config KEYS_REQUEST_CACHE
  25        bool "Enable temporary caching of the last request_key() result"
  26        depends on KEYS
  27        help
  28          This option causes the result of the last successful request_key()
  29          call that didn't upcall to the kernel to be cached temporarily in the
  30          task_struct.  The cache is cleared by exit and just prior to the
  31          resumption of userspace.
  32
  33          This allows the key used for multiple step processes where each step
  34          wants to request a key that is likely the same as the one requested
  35          by the last step to save on the searching.
  36
  37          An example of such a process is a pathwalk through a network
  38          filesystem in which each method needs to request an authentication
  39          key.  Pathwalk will call multiple methods for each dentry traversed
  40          (permission, d_revalidate, lookup, getxattr, getacl, ...).
  41
  42config PERSISTENT_KEYRINGS
  43        bool "Enable register of persistent per-UID keyrings"
  44        depends on KEYS
  45        help
  46          This option provides a register of persistent per-UID keyrings,
  47          primarily aimed at Kerberos key storage.  The keyrings are persistent
  48          in the sense that they stay around after all processes of that UID
  49          have exited, not that they survive the machine being rebooted.
  50
  51          A particular keyring may be accessed by either the user whose keyring
  52          it is or by a process with administrative privileges.  The active
  53          LSMs gets to rule on which admin-level processes get to access the
  54          cache.
  55
  56          Keyrings are created and added into the register upon demand and get
  57          removed if they expire (a default timeout is set upon creation).
  58
  59config BIG_KEYS
  60        bool "Large payload keys"
  61        depends on KEYS
  62        depends on TMPFS
  63        depends on CRYPTO_LIB_CHACHA20POLY1305 = y
  64        help
  65          This option provides support for holding large keys within the kernel
  66          (for example Kerberos ticket caches).  The data may be stored out to
  67          swapspace by tmpfs.
  68
  69          If you are unsure as to whether this is required, answer N.
  70
  71config TRUSTED_KEYS
  72        tristate "TRUSTED KEYS"
  73        depends on KEYS && TCG_TPM
  74        select CRYPTO
  75        select CRYPTO_HMAC
  76        select CRYPTO_SHA1
  77        select CRYPTO_HASH_INFO
  78        select ASN1_ENCODER
  79        select OID_REGISTRY
  80        select ASN1
  81        help
  82          This option provides support for creating, sealing, and unsealing
  83          keys in the kernel. Trusted keys are random number symmetric keys,
  84          generated and RSA-sealed by the TPM. The TPM only unseals the keys,
  85          if the boot PCRs and other criteria match.  Userspace will only ever
  86          see encrypted blobs.
  87
  88          If you are unsure as to whether this is required, answer N.
  89
  90config ENCRYPTED_KEYS
  91        tristate "ENCRYPTED KEYS"
  92        depends on KEYS
  93        select CRYPTO
  94        select CRYPTO_HMAC
  95        select CRYPTO_AES
  96        select CRYPTO_CBC
  97        select CRYPTO_SHA256
  98        select CRYPTO_RNG
  99        help
 100          This option provides support for create/encrypting/decrypting keys
 101          in the kernel.  Encrypted keys are kernel generated random numbers,
 102          which are encrypted/decrypted with a 'master' symmetric key. The
 103          'master' key can be either a trusted-key or user-key type.
 104          Userspace only ever sees/stores encrypted blobs.
 105
 106          If you are unsure as to whether this is required, answer N.
 107
 108config KEY_DH_OPERATIONS
 109       bool "Diffie-Hellman operations on retained keys"
 110       depends on KEYS
 111       select CRYPTO
 112       select CRYPTO_HASH
 113       select CRYPTO_DH
 114       help
 115         This option provides support for calculating Diffie-Hellman
 116         public keys and shared secrets using values stored as keys
 117         in the kernel.
 118
 119         If you are unsure as to whether this is required, answer N.
 120
 121config KEY_NOTIFICATIONS
 122        bool "Provide key/keyring change notifications"
 123        depends on KEYS && WATCH_QUEUE
 124        help
 125          This option provides support for getting change notifications
 126          on keys and keyrings on which the caller has View permission.
 127          This makes use of pipes to handle the notification buffer and
 128          provides KEYCTL_WATCH_KEY to enable/disable watches.
 129