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 64 select CRYPTO_AES 65 select CRYPTO_GCM 66 help 67 This option provides support for holding large keys within the kernel 68 (for example Kerberos ticket caches). The data may be stored out to 69 swapspace by tmpfs. 70 71 If you are unsure as to whether this is required, answer N. 72 73config TRUSTED_KEYS 74 tristate "TRUSTED KEYS" 75 depends on KEYS && TCG_TPM 76 select CRYPTO 77 select CRYPTO_HMAC 78 select CRYPTO_SHA1 79 select CRYPTO_HASH_INFO 80 help 81 This option provides support for creating, sealing, and unsealing 82 keys in the kernel. Trusted keys are random number symmetric keys, 83 generated and RSA-sealed by the TPM. The TPM only unseals the keys, 84 if the boot PCRs and other criteria match. Userspace will only ever 85 see encrypted blobs. 86 87 If you are unsure as to whether this is required, answer N. 88 89config ENCRYPTED_KEYS 90 tristate "ENCRYPTED KEYS" 91 depends on KEYS 92 select CRYPTO 93 select CRYPTO_HMAC 94 select CRYPTO_AES 95 select CRYPTO_CBC 96 select CRYPTO_SHA256 97 select CRYPTO_RNG 98 help 99 This option provides support for create/encrypting/decrypting keys 100 in the kernel. Encrypted keys are kernel generated random numbers, 101 which are encrypted/decrypted with a 'master' symmetric key. The 102 'master' key can be either a trusted-key or user-key type. 103 Userspace only ever sees/stores encrypted blobs. 104 105 If you are unsure as to whether this is required, answer N. 106 107config KEY_DH_OPERATIONS 108 bool "Diffie-Hellman operations on retained keys" 109 depends on KEYS 110 select CRYPTO 111 select CRYPTO_HASH 112 select CRYPTO_DH 113 help 114 This option provides support for calculating Diffie-Hellman 115 public keys and shared secrets using values stored as keys 116 in the kernel. 117 118 If you are unsure as to whether this is required, answer N. 119