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
   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/module-signing.txt
  17
  18 config SYSTEM_TRUSTED_KEYRING
  19         bool "Provide system-wide ring of trusted keys"
  20         depends on KEYS
  21         depends on ASYMMETRIC_KEY_TYPE
  22         help
  23           Provide a system keyring to which trusted keys can be added.  Keys in
  24           the keyring are considered to be trusted.  Keys may be added at will
  25           by the kernel from compiled-in data and from hardware key stores, but
  26           userspace may only add extra keys if those keys can be verified by
  27           keys already in the keyring.
  28
  29           Keys in this keyring are used by module signature checking.
  30
  31 config SYSTEM_TRUSTED_KEYS
  32         string "Additional X.509 keys for default system keyring"
  33         depends on SYSTEM_TRUSTED_KEYRING
  34         help
  35           If set, this option should be the filename of a PEM-formatted file
  36           containing trusted X.509 certificates to be included in the default
  37           system keyring. Any certificate used for module signing is implicitly
  38           also trusted.
  39
  40           NOTE: If you previously provided keys for the system keyring in the
  41           form of DER-encoded *.x509 files in the top-level build directory,
  42           those are no longer used. You will need to set this option instead.
  43
  44 config SYSTEM_EXTRA_CERTIFICATE
  45         bool "Reserve area for inserting a certificate without recompiling"
  46         depends on SYSTEM_TRUSTED_KEYRING
  47         help
  48           If set, space for an extra certificate will be reserved in the kernel
  49           image. This allows introducing a trusted certificate to the default
  50           system keyring without recompiling the kernel.
  51
  52 config SYSTEM_EXTRA_CERTIFICATE_SIZE
  53         int "Number of bytes to reserve for the extra certificate"
  54         depends on SYSTEM_EXTRA_CERTIFICATE
  55         default 4096
  56         help
  57           This is the number of bytes reserved in the kernel image for a
  58           certificate to be inserted.
  59
  60 config SECONDARY_TRUSTED_KEYRING
  61         bool "Provide a keyring to which extra trustable keys may be added"
  62         depends on SYSTEM_TRUSTED_KEYRING
  63         help
  64           If set, provide a keyring to which extra keys may be added, provided
  65           those keys are not blacklisted and are vouched for by a key built
  66           into the kernel or already in the secondary trusted keyring.
  67
  68 config SYSTEM_BLACKLIST_KEYRING
  69         bool "Provide system-wide ring of blacklisted keys"
  70         depends on KEYS
  71         help
  72           Provide a system keyring to which blacklisted keys can be added.
  73           Keys in the keyring are considered entirely untrusted.  Keys in this
  74           keyring are used by the module signature checking to reject loading
  75           of modules signed with a blacklisted key.
  76
  77 config SYSTEM_BLACKLIST_HASH_LIST
  78         string "Hashes to be preloaded into the system blacklist keyring"
  79         depends on SYSTEM_BLACKLIST_KEYRING
  80         help
  81           If set, this option should be the filename of a list of hashes in the
  82           form "<hash>", "<hash>", ... .  This will be included into a C
  83           wrapper to incorporate the list into the kernel.  Each <hash> should
  84           be a string of hex digits.
  85
  86 config EFI_SIGNATURE_LIST_PARSER
  87         bool "EFI signature list parser"
  88         depends on EFI
  89         select X509_CERTIFICATE_PARSER
  90         help
  91           This option provides support for parsing EFI signature lists for
  92           X.509 certificates and turning them into keys.
  93
  94 config LOAD_UEFI_KEYS
  95         bool "Load certs and blacklist from UEFI db for module checking"
  96         depends on SYSTEM_BLACKLIST_KEYRING
  97         depends on SECONDARY_TRUSTED_KEYRING
  98         depends on EFI
  99         depends on EFI_SIGNATURE_LIST_PARSER
 100         help
 101           If the kernel is booted in secure boot mode, this option will cause
 102           the kernel to load the certificates from the UEFI db and MokListRT
 103           into the secondary trusted keyring.  It will also load any X.509
 104           SHA256 hashes in the dbx list into the blacklist.
 105
 106           The effect of this is that, if the kernel is booted in secure boot
 107           mode, modules signed with UEFI-stored keys will be permitted to be
 108           loaded and keys that match the blacklist will be rejected.
 109
 110 endmenu