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, machine keyring (if configured), or already in the 92 secondary trusted keyring. 93 94config SECONDARY_TRUSTED_KEYRING_SIGNED_BY_BUILTIN 95 bool "Only allow additional certs signed by keys on the builtin trusted keyring" 96 depends on SECONDARY_TRUSTED_KEYRING 97 help 98 If set, only certificates signed by keys on the builtin trusted 99 keyring may be loaded onto the secondary trusted keyring. 100 101 Note: The machine keyring, if configured, will be linked to the 102 secondary keyring. When enabling this option, it is recommended 103 to also configure INTEGRITY_CA_MACHINE_KEYRING_MAX to prevent 104 linking code signing keys with imputed trust to the secondary 105 trusted keyring. 106 107config SYSTEM_BLACKLIST_KEYRING 108 bool "Provide system-wide ring of blacklisted keys" 109 depends on KEYS 110 help 111 Provide a system keyring to which blacklisted keys can be added. 112 Keys in the keyring are considered entirely untrusted. Keys in this 113 keyring are used by the module signature checking to reject loading 114 of modules signed with a blacklisted key. 115 116config SYSTEM_BLACKLIST_HASH_LIST 117 string "Hashes to be preloaded into the system blacklist keyring" 118 depends on SYSTEM_BLACKLIST_KEYRING 119 help 120 If set, this option should be the filename of a list of hashes in the 121 form "<hash>", "<hash>", ... . This will be included into a C 122 wrapper to incorporate the list into the kernel. Each <hash> must be a 123 string starting with a prefix ("tbs" or "bin"), then a colon (":"), and 124 finally an even number of hexadecimal lowercase characters (up to 128). 125 Certificate hashes can be generated with 126 tools/certs/print-cert-tbs-hash.sh . 127 128config SYSTEM_REVOCATION_LIST 129 bool "Provide system-wide ring of revocation certificates" 130 depends on SYSTEM_BLACKLIST_KEYRING 131 depends on PKCS7_MESSAGE_PARSER=y 132 help 133 If set, this allows revocation certificates to be stored in the 134 blacklist keyring and implements a hook whereby a PKCS#7 message can 135 be checked to see if it matches such a certificate. 136 137config SYSTEM_REVOCATION_KEYS 138 string "X.509 certificates to be preloaded into the system blacklist keyring" 139 depends on SYSTEM_REVOCATION_LIST 140 help 141 If set, this option should be the filename of a PEM-formatted file 142 containing X.509 certificates to be included in the default blacklist 143 keyring. 144 145config SYSTEM_BLACKLIST_AUTH_UPDATE 146 bool "Allow root to add signed blacklist keys" 147 depends on SYSTEM_BLACKLIST_KEYRING 148 depends on SYSTEM_DATA_VERIFICATION 149 help 150 If set, provide the ability to load new blacklist keys at run time if 151 they are signed and vouched by a certificate from the builtin trusted 152 keyring. The PKCS#7 signature of the description is set in the key 153 payload. Blacklist keys cannot be removed. 154 155endmenu 156