1 # SPDX-License-Identifier: GPL-2.0
2 menu "Certificates for signature checking"
3
4 config 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
18 choice
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
25 config MODULE_SIG_KEY_TYPE_RSA
26 bool "RSA"
27 help
28 Use an RSA key for module signing.
29
30 config MODULE_SIG_KEY_TYPE_ECDSA
31 bool "ECDSA"
32 select CRYPTO_ECDSA
33 depends on !(MODULE_SIG_SHA256 || MODULE_SIG_SHA3_256)
34 help
35 Use an elliptic curve key (NIST P384) for module signing. Use
36 a strong hash of same or higher bit length, i.e. sha384 or
37 sha512 for hashing modules.
38
39 Note: Remove all ECDSA signing keys, e.g. certs/signing_key.pem,
40 when falling back to building Linux 5.14 and older kernels.
41
42 endchoice
43
44 config SYSTEM_TRUSTED_KEYRING
45 bool "Provide system-wide ring of trusted keys"
46 depends on KEYS
47 depends on ASYMMETRIC_KEY_TYPE
48 depends on X509_CERTIFICATE_PARSER = y
49 help
50 Provide a system keyring to which trusted keys can be added. Keys in
51 the keyring are considered to be trusted. Keys may be added at will
52 by the kernel from compiled-in data and from hardware key stores, but
53 userspace may only add extra keys if those keys can be verified by
54 keys already in the keyring.
55
56 Keys in this keyring are used by module signature checking.
57
58 config SYSTEM_TRUSTED_KEYS
59 string "Additional X.509 keys for default system keyring"
60 depends on SYSTEM_TRUSTED_KEYRING
61 help
62 If set, this option should be the filename of a PEM-formatted file
63 containing trusted X.509 certificates to be included in the default
64 system keyring. Any certificate used for module signing is implicitly
65 also trusted.
66
67 NOTE: If you previously provided keys for the system keyring in the
68 form of DER-encoded *.x509 files in the top-level build directory,
69 those are no longer used. You will need to set this option instead.
70
71 config SYSTEM_EXTRA_CERTIFICATE
72 bool "Reserve area for inserting a certificate without recompiling"
73 depends on SYSTEM_TRUSTED_KEYRING
74 help
75 If set, space for an extra certificate will be reserved in the kernel
76 image. This allows introducing a trusted certificate to the default
77 system keyring without recompiling the kernel.
78
79 config SYSTEM_EXTRA_CERTIFICATE_SIZE
80 int "Number of bytes to reserve for the extra certificate"
81 depends on SYSTEM_EXTRA_CERTIFICATE
82 default 4096
83 help
84 This is the number of bytes reserved in the kernel image for a
85 certificate to be inserted.
86
87 config SECONDARY_TRUSTED_KEYRING
88 bool "Provide a keyring to which extra trustable keys may be added"
89 depends on SYSTEM_TRUSTED_KEYRING
90 help
91 If set, provide a keyring to which extra keys may be added, provided
92 those keys are not blacklisted and are vouched for by a key built
93 into the kernel, machine keyring (if configured), or already in the
94 secondary trusted keyring.
95
96 config SECONDARY_TRUSTED_KEYRING_SIGNED_BY_BUILTIN
97 bool "Only allow additional certs signed by keys on the builtin trusted keyring"
98 depends on SECONDARY_TRUSTED_KEYRING
99 help
100 If set, only certificates signed by keys on the builtin trusted
101 keyring may be loaded onto the secondary trusted keyring.
102
103 Note: The machine keyring, if configured, will be linked to the
104 secondary keyring. When enabling this option, it is recommended
105 to also configure INTEGRITY_CA_MACHINE_KEYRING_MAX to prevent
106 linking code signing keys with imputed trust to the secondary
107 trusted keyring.
108
109 config SYSTEM_BLACKLIST_KEYRING
110 bool "Provide system-wide ring of blacklisted keys"
111 depends on KEYS
112 help
113 Provide a system keyring to which blacklisted keys can be added.
114 Keys in the keyring are considered entirely untrusted. Keys in this
115 keyring are used by the module signature checking to reject loading
116 of modules signed with a blacklisted key.
117
118 config SYSTEM_BLACKLIST_HASH_LIST
119 string "Hashes to be preloaded into the system blacklist keyring"
120 depends on SYSTEM_BLACKLIST_KEYRING
121 help
122 If set, this option should be the filename of a list of hashes in the
123 form "<hash>", "<hash>", ... . This will be included into a C
124 wrapper to incorporate the list into the kernel. Each <hash> must be a
125 string starting with a prefix ("tbs" or "bin"), then a colon (":"), and
126 finally an even number of hexadecimal lowercase characters (up to 128).
127 Certificate hashes can be generated with
128 tools/certs/print-cert-tbs-hash.sh .
129
130 config SYSTEM_REVOCATION_LIST
131 bool "Provide system-wide ring of revocation certificates"
132 depends on SYSTEM_BLACKLIST_KEYRING
133 depends on PKCS7_MESSAGE_PARSER=y
134 help
135 If set, this allows revocation certificates to be stored in the
136 blacklist keyring and implements a hook whereby a PKCS#7 message can
137 be checked to see if it matches such a certificate.
138
139 config SYSTEM_REVOCATION_KEYS
140 string "X.509 certificates to be preloaded into the system blacklist keyring"
141 depends on SYSTEM_REVOCATION_LIST
142 help
143 If set, this option should be the filename of a PEM-formatted file
144 containing X.509 certificates to be included in the default blacklist
145 keyring.
146
147 config SYSTEM_BLACKLIST_AUTH_UPDATE
148 bool "Allow root to add signed blacklist keys"
149 depends on SYSTEM_BLACKLIST_KEYRING
150 depends on SYSTEM_DATA_VERIFICATION
151 help
152 If set, provide the ability to load new blacklist keys at run time if
153 they are signed and vouched by a certificate from the builtin trusted
154 keyring. The PKCS#7 signature of the description is set in the key
155 payload. Blacklist keys cannot be removed.
156
157 endmenu
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