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 help 79 This option provides support for creating, sealing, and unsealing 80 keys in the kernel. Trusted keys are random number symmetric keys, 81 generated and RSA-sealed by the TPM. The TPM only unseals the keys, 82 if the boot PCRs and other criteria match. Userspace will only ever 83 see encrypted blobs. 84 85 If you are unsure as to whether this is required, answer N. 86 87config ENCRYPTED_KEYS 88 tristate "ENCRYPTED KEYS" 89 depends on KEYS 90 select CRYPTO 91 select CRYPTO_HMAC 92 select CRYPTO_AES 93 select CRYPTO_CBC 94 select CRYPTO_SHA256 95 select CRYPTO_RNG 96 help 97 This option provides support for create/encrypting/decrypting keys 98 in the kernel. Encrypted keys are kernel generated random numbers, 99 which are encrypted/decrypted with a 'master' symmetric key. The 100 'master' key can be either a trusted-key or user-key type. 101 Userspace only ever sees/stores encrypted blobs. 102 103 If you are unsure as to whether this is required, answer N. 104 105config KEY_DH_OPERATIONS 106 bool "Diffie-Hellman operations on retained keys" 107 depends on KEYS 108 select CRYPTO 109 select CRYPTO_HASH 110 select CRYPTO_DH 111 help 112 This option provides support for calculating Diffie-Hellman 113 public keys and shared secrets using values stored as keys 114 in the kernel. 115 116 If you are unsure as to whether this is required, answer N. 117 118config KEY_NOTIFICATIONS 119 bool "Provide key/keyring change notifications" 120 depends on KEYS && WATCH_QUEUE 121 help 122 This option provides support for getting change notifications 123 on keys and keyrings on which the caller has View permission. 124 This makes use of pipes to handle the notification buffer and 125 provides KEYCTL_WATCH_KEY to enable/disable watches. 126