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_COMPAT
25	def_bool y
26	depends on COMPAT && KEYS
27
28config KEYS_REQUEST_CACHE
29	bool "Enable temporary caching of the last request_key() result"
30	depends on KEYS
31	help
32	  This option causes the result of the last successful request_key()
33	  call that didn't upcall to the kernel to be cached temporarily in the
34	  task_struct.  The cache is cleared by exit and just prior to the
35	  resumption of userspace.
36
37	  This allows the key used for multiple step processes where each step
38	  wants to request a key that is likely the same as the one requested
39	  by the last step to save on the searching.
40
41	  An example of such a process is a pathwalk through a network
42	  filesystem in which each method needs to request an authentication
43	  key.  Pathwalk will call multiple methods for each dentry traversed
44	  (permission, d_revalidate, lookup, getxattr, getacl, ...).
45
46config PERSISTENT_KEYRINGS
47	bool "Enable register of persistent per-UID keyrings"
48	depends on KEYS
49	help
50	  This option provides a register of persistent per-UID keyrings,
51	  primarily aimed at Kerberos key storage.  The keyrings are persistent
52	  in the sense that they stay around after all processes of that UID
53	  have exited, not that they survive the machine being rebooted.
54
55	  A particular keyring may be accessed by either the user whose keyring
56	  it is or by a process with administrative privileges.  The active
57	  LSMs gets to rule on which admin-level processes get to access the
58	  cache.
59
60	  Keyrings are created and added into the register upon demand and get
61	  removed if they expire (a default timeout is set upon creation).
62
63config BIG_KEYS
64	bool "Large payload keys"
65	depends on KEYS
66	depends on TMPFS
67	select CRYPTO
68	select CRYPTO_AES
69	select CRYPTO_GCM
70	help
71	  This option provides support for holding large keys within the kernel
72	  (for example Kerberos ticket caches).  The data may be stored out to
73	  swapspace by tmpfs.
74
75	  If you are unsure as to whether this is required, answer N.
76
77config TRUSTED_KEYS
78	tristate "TRUSTED KEYS"
79	depends on KEYS && TCG_TPM
80	select CRYPTO
81	select CRYPTO_HMAC
82	select CRYPTO_SHA1
83	select CRYPTO_HASH_INFO
84	help
85	  This option provides support for creating, sealing, and unsealing
86	  keys in the kernel. Trusted keys are random number symmetric keys,
87	  generated and RSA-sealed by the TPM. The TPM only unseals the keys,
88	  if the boot PCRs and other criteria match.  Userspace will only ever
89	  see encrypted blobs.
90
91	  If you are unsure as to whether this is required, answer N.
92
93config ENCRYPTED_KEYS
94	tristate "ENCRYPTED KEYS"
95	depends on KEYS
96	select CRYPTO
97	select CRYPTO_HMAC
98	select CRYPTO_AES
99	select CRYPTO_CBC
100	select CRYPTO_SHA256
101	select CRYPTO_RNG
102	help
103	  This option provides support for create/encrypting/decrypting keys
104	  in the kernel.  Encrypted keys are kernel generated random numbers,
105	  which are encrypted/decrypted with a 'master' symmetric key. The
106	  'master' key can be either a trusted-key or user-key type.
107	  Userspace only ever sees/stores encrypted blobs.
108
109	  If you are unsure as to whether this is required, answer N.
110
111config KEY_DH_OPERATIONS
112       bool "Diffie-Hellman operations on retained keys"
113       depends on KEYS
114       select CRYPTO
115       select CRYPTO_HASH
116       select CRYPTO_DH
117       help
118	 This option provides support for calculating Diffie-Hellman
119	 public keys and shared secrets using values stored as keys
120	 in the kernel.
121
122	 If you are unsure as to whether this is required, answer N.
123