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 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 42endchoice 43 44config 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 58config 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 71config 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 79config 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 87config 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 96config 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 109config 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 118config 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 130config 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 139config 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 147config 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 157endmenu 158