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 select CRYPTO_LIB_CHACHA20POLY1305 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 74 help 75 This option provides support for creating, sealing, and unsealing 76 keys in the kernel. Trusted keys are random number symmetric keys, 77 generated and sealed by a trust source selected at kernel boot-time. 78 Userspace will only ever see encrypted blobs. 79 80 If you are unsure as to whether this is required, answer N. 81 82if TRUSTED_KEYS 83source "security/keys/trusted-keys/Kconfig" 84endif 85 86config ENCRYPTED_KEYS 87 tristate "ENCRYPTED KEYS" 88 depends on KEYS 89 select CRYPTO 90 select CRYPTO_AES 91 select CRYPTO_CBC 92 select CRYPTO_LIB_SHA256 93 select CRYPTO_RNG 94 help 95 This option provides support for create/encrypting/decrypting keys 96 in the kernel. Encrypted keys are instantiated using kernel 97 generated random numbers or provided decrypted data, and are 98 encrypted/decrypted with a 'master' symmetric key. The 'master' 99 key can be either a trusted-key or user-key type. Only encrypted 100 blobs are ever output to Userspace. 101 102 If you are unsure as to whether this is required, answer N. 103 104config USER_DECRYPTED_DATA 105 bool "Allow encrypted keys with user decrypted data" 106 depends on ENCRYPTED_KEYS 107 help 108 This option provides support for instantiating encrypted keys using 109 user-provided decrypted data. The decrypted data must be hex-ascii 110 encoded. 111 112 If you are unsure as to whether this is required, answer N. 113 114config KEY_DH_OPERATIONS 115 bool "Diffie-Hellman operations on retained keys" 116 depends on KEYS 117 select CRYPTO 118 select CRYPTO_KDF800108_CTR 119 select CRYPTO_DH 120 help 121 This option provides support for calculating Diffie-Hellman 122 public keys and shared secrets using values stored as keys 123 in the kernel. 124 125 If you are unsure as to whether this is required, answer N. 126 127config KEY_NOTIFICATIONS 128 bool "Provide key/keyring change notifications" 129 depends on KEYS && WATCH_QUEUE 130 help 131 This option provides support for getting change notifications 132 on keys and keyrings on which the caller has View permission. 133 This makes use of pipes to handle the notification buffer and 134 provides KEYCTL_WATCH_KEY to enable/disable watches. 135