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