xref: /openbmc/linux/certs/Kconfig (revision 2154aca2)
1# SPDX-License-Identifier: GPL-2.0
2menu "Certificates for signature checking"
3
4config MODULE_SIG_KEY
5	string "File name or PKCS#11 URI of module signing key"
6	default "certs/signing_key.pem"
7	depends on MODULE_SIG || (IMA_APPRAISE_MODSIG && MODULES)
8	help
9         Provide the file name of a private key/certificate in PEM format,
10         or a PKCS#11 URI according to RFC7512. The file should contain, or
11         the URI should identify, both the certificate and its corresponding
12         private key.
13
14         If this option is unchanged from its default "certs/signing_key.pem",
15         then the kernel will automatically generate the private key and
16         certificate as described in Documentation/admin-guide/module-signing.rst
17
18choice
19	prompt "Type of module signing key to be generated"
20	depends on MODULE_SIG || (IMA_APPRAISE_MODSIG && MODULES)
21	help
22	 The type of module signing key type to generate. This option
23	 does not apply if a #PKCS11 URI is used.
24
25config MODULE_SIG_KEY_TYPE_RSA
26	bool "RSA"
27	help
28	 Use an RSA key for module signing.
29
30config MODULE_SIG_KEY_TYPE_ECDSA
31	bool "ECDSA"
32	select CRYPTO_ECDSA
33	help
34	 Use an elliptic curve key (NIST P384) for module signing. Consider
35	 using a strong hash like sha256 or sha384 for hashing modules.
36
37	 Note: Remove all ECDSA signing keys, e.g. certs/signing_key.pem,
38	 when falling back to building Linux 5.14 and older kernels.
39
40endchoice
41
42config SYSTEM_TRUSTED_KEYRING
43	bool "Provide system-wide ring of trusted keys"
44	depends on KEYS
45	depends on ASYMMETRIC_KEY_TYPE
46	depends on X509_CERTIFICATE_PARSER = y
47	help
48	  Provide a system keyring to which trusted keys can be added.  Keys in
49	  the keyring are considered to be trusted.  Keys may be added at will
50	  by the kernel from compiled-in data and from hardware key stores, but
51	  userspace may only add extra keys if those keys can be verified by
52	  keys already in the keyring.
53
54	  Keys in this keyring are used by module signature checking.
55
56config SYSTEM_TRUSTED_KEYS
57	string "Additional X.509 keys for default system keyring"
58	depends on SYSTEM_TRUSTED_KEYRING
59	help
60	  If set, this option should be the filename of a PEM-formatted file
61	  containing trusted X.509 certificates to be included in the default
62	  system keyring. Any certificate used for module signing is implicitly
63	  also trusted.
64
65	  NOTE: If you previously provided keys for the system keyring in the
66	  form of DER-encoded *.x509 files in the top-level build directory,
67	  those are no longer used. You will need to set this option instead.
68
69config SYSTEM_EXTRA_CERTIFICATE
70	bool "Reserve area for inserting a certificate without recompiling"
71	depends on SYSTEM_TRUSTED_KEYRING
72	help
73	  If set, space for an extra certificate will be reserved in the kernel
74	  image. This allows introducing a trusted certificate to the default
75	  system keyring without recompiling the kernel.
76
77config SYSTEM_EXTRA_CERTIFICATE_SIZE
78	int "Number of bytes to reserve for the extra certificate"
79	depends on SYSTEM_EXTRA_CERTIFICATE
80	default 4096
81	help
82	  This is the number of bytes reserved in the kernel image for a
83	  certificate to be inserted.
84
85config SECONDARY_TRUSTED_KEYRING
86	bool "Provide a keyring to which extra trustable keys may be added"
87	depends on SYSTEM_TRUSTED_KEYRING
88	help
89	  If set, provide a keyring to which extra keys may be added, provided
90	  those keys are not blacklisted and are vouched for by a key built
91	  into the kernel or already in the secondary trusted keyring.
92
93config SYSTEM_BLACKLIST_KEYRING
94	bool "Provide system-wide ring of blacklisted keys"
95	depends on KEYS
96	help
97	  Provide a system keyring to which blacklisted keys can be added.
98	  Keys in the keyring are considered entirely untrusted.  Keys in this
99	  keyring are used by the module signature checking to reject loading
100	  of modules signed with a blacklisted key.
101
102config SYSTEM_BLACKLIST_HASH_LIST
103	string "Hashes to be preloaded into the system blacklist keyring"
104	depends on SYSTEM_BLACKLIST_KEYRING
105	help
106	  If set, this option should be the filename of a list of hashes in the
107	  form "<hash>", "<hash>", ... .  This will be included into a C
108	  wrapper to incorporate the list into the kernel.  Each <hash> must be a
109	  string starting with a prefix ("tbs" or "bin"), then a colon (":"), and
110	  finally an even number of hexadecimal lowercase characters (up to 128).
111	  Certificate hashes can be generated with
112	  tools/certs/print-cert-tbs-hash.sh .
113
114config SYSTEM_REVOCATION_LIST
115	bool "Provide system-wide ring of revocation certificates"
116	depends on SYSTEM_BLACKLIST_KEYRING
117	depends on PKCS7_MESSAGE_PARSER=y
118	help
119	  If set, this allows revocation certificates to be stored in the
120	  blacklist keyring and implements a hook whereby a PKCS#7 message can
121	  be checked to see if it matches such a certificate.
122
123config SYSTEM_REVOCATION_KEYS
124	string "X.509 certificates to be preloaded into the system blacklist keyring"
125	depends on SYSTEM_REVOCATION_LIST
126	help
127	  If set, this option should be the filename of a PEM-formatted file
128	  containing X.509 certificates to be included in the default blacklist
129	  keyring.
130
131config SYSTEM_BLACKLIST_AUTH_UPDATE
132	bool "Allow root to add signed blacklist keys"
133	depends on SYSTEM_BLACKLIST_KEYRING
134	depends on SYSTEM_DATA_VERIFICATION
135	help
136	  If set, provide the ability to load new blacklist keys at run time if
137	  they are signed and vouched by a certificate from the builtin trusted
138	  keyring.  The PKCS#7 signature of the description is set in the key
139	  payload.  Blacklist keys cannot be removed.
140
141endmenu
142