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# SPDX-License-Identifier: GPL-2.0
menu "Certificates for signature checking"
config MODULE_SIG_KEY
string "File name or PKCS#11 URI of module signing key"
default "certs/signing_key.pem"
depends on MODULE_SIG || (IMA_APPRAISE_MODSIG && MODULES)
help
Provide the file name of a private key/certificate in PEM format,
or a PKCS#11 URI according to RFC7512. The file should contain, or
the URI should identify, both the certificate and its corresponding
private key.
If this option is unchanged from its default "certs/signing_key.pem",
then the kernel will automatically generate the private key and
certificate as described in Documentation/admin-guide/module-signing.rst
choice
prompt "Type of module signing key to be generated"
depends on MODULE_SIG || (IMA_APPRAISE_MODSIG && MODULES)
help
The type of module signing key type to generate. This option
does not apply if a #PKCS11 URI is used.
config MODULE_SIG_KEY_TYPE_RSA
bool "RSA"
help
Use an RSA key for module signing.
config MODULE_SIG_KEY_TYPE_ECDSA
bool "ECDSA"
select CRYPTO_ECDSA
help
Use an elliptic curve key (NIST P384) for module signing. Consider
using a strong hash like sha256 or sha384 for hashing modules.
Note: Remove all ECDSA signing keys, e.g. certs/signing_key.pem,
when falling back to building Linux 5.14 and older kernels.
endchoice
config SYSTEM_TRUSTED_KEYRING
bool "Provide system-wide ring of trusted keys"
depends on KEYS
depends on ASYMMETRIC_KEY_TYPE
depends on X509_CERTIFICATE_PARSER = y
help
Provide a system keyring to which trusted keys can be added. Keys in
the keyring are considered to be trusted. Keys may be added at will
by the kernel from compiled-in data and from hardware key stores, but
userspace may only add extra keys if those keys can be verified by
keys already in the keyring.
Keys in this keyring are used by module signature checking.
config SYSTEM_TRUSTED_KEYS
string "Additional X.509 keys for default system keyring"
depends on SYSTEM_TRUSTED_KEYRING
help
If set, this option should be the filename of a PEM-formatted file
containing trusted X.509 certificates to be included in the default
system keyring. Any certificate used for module signing is implicitly
also trusted.
NOTE: If you previously provided keys for the system keyring in the
form of DER-encoded *.x509 files in the top-level build directory,
those are no longer used. You will need to set this option instead.
config SYSTEM_EXTRA_CERTIFICATE
bool "Reserve area for inserting a certificate without recompiling"
depends on SYSTEM_TRUSTED_KEYRING
help
If set, space for an extra certificate will be reserved in the kernel
image. This allows introducing a trusted certificate to the default
system keyring without recompiling the kernel.
config SYSTEM_EXTRA_CERTIFICATE_SIZE
int "Number of bytes to reserve for the extra certificate"
depends on SYSTEM_EXTRA_CERTIFICATE
default 4096
help
This is the number of bytes reserved in the kernel image for a
certificate to be inserted.
config SECONDARY_TRUSTED_KEYRING
bool "Provide a keyring to which extra trustable keys may be added"
depends on SYSTEM_TRUSTED_KEYRING
help
If set, provide a keyring to which extra keys may be added, provided
those keys are not blacklisted and are vouched for by a key built
into the kernel, machine keyring (if configured), or already in the
secondary trusted keyring.
config SECONDARY_TRUSTED_KEYRING_SIGNED_BY_BUILTIN
bool "Only allow additional certs signed by keys on the builtin trusted keyring"
depends on SECONDARY_TRUSTED_KEYRING
help
If set, only certificates signed by keys on the builtin trusted
keyring may be loaded onto the secondary trusted keyring.
Note: The machine keyring, if configured, will be linked to the
secondary keyring. When enabling this option, it is recommended
to also configure INTEGRITY_CA_MACHINE_KEYRING_MAX to prevent
linking code signing keys with imputed trust to the secondary
trusted keyring.
config SYSTEM_BLACKLIST_KEYRING
bool "Provide system-wide ring of blacklisted keys"
depends on KEYS
help
Provide a system keyring to which blacklisted keys can be added.
Keys in the keyring are considered entirely untrusted. Keys in this
keyring are used by the module signature checking to reject loading
of modules signed with a blacklisted key.
config SYSTEM_BLACKLIST_HASH_LIST
string "Hashes to be preloaded into the system blacklist keyring"
depends on SYSTEM_BLACKLIST_KEYRING
help
If set, this option should be the filename of a list of hashes in the
form "<hash>", "<hash>", ... . This will be included into a C
wrapper to incorporate the list into the kernel. Each <hash> must be a
string starting with a prefix ("tbs" or "bin"), then a colon (":"), and
finally an even number of hexadecimal lowercase characters (up to 128).
Certificate hashes can be generated with
tools/certs/print-cert-tbs-hash.sh .
config SYSTEM_REVOCATION_LIST
bool "Provide system-wide ring of revocation certificates"
depends on SYSTEM_BLACKLIST_KEYRING
depends on PKCS7_MESSAGE_PARSER=y
help
If set, this allows revocation certificates to be stored in the
blacklist keyring and implements a hook whereby a PKCS#7 message can
be checked to see if it matches such a certificate.
config SYSTEM_REVOCATION_KEYS
string "X.509 certificates to be preloaded into the system blacklist keyring"
depends on SYSTEM_REVOCATION_LIST
help
If set, this option should be the filename of a PEM-formatted file
containing X.509 certificates to be included in the default blacklist
keyring.
config SYSTEM_BLACKLIST_AUTH_UPDATE
bool "Allow root to add signed blacklist keys"
depends on SYSTEM_BLACKLIST_KEYRING
depends on SYSTEM_DATA_VERIFICATION
help
If set, provide the ability to load new blacklist keys at run time if
they are signed and vouched by a certificate from the builtin trusted
keyring. The PKCS#7 signature of the description is set in the key
payload. Blacklist keys cannot be removed.
endmenu
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