certs/Kconfig

   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         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
  40 endchoice
  41
  42 config 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
  56 config 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
  69 config 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
  77 config 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
  85 config 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
  93 config 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
 102 config 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
 114 config 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
 123 config 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
 131 config 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
 141 endmenu