be07858fbf
With recent rework, trusted keys are no longer limited to TPM as trust
source. The Kconfig symbol is unchanged however leading to a few issues:
- TCG_TPM is required, even if only TEE is to be used
- Enabling TCG_TPM, but excluding it from available trusted sources
is not possible
- TEE=m && TRUSTED_KEYS=y will lead to TEE support being silently
dropped, which is not the best user experience
Remedy these issues by introducing two new boolean Kconfig symbols:
TRUSTED_KEYS_TPM and TRUSTED_KEYS_TEE with the appropriate
dependencies.
Any new code depending on the TPM trusted key backend in particular
or symbols exported by it will now need to explicitly state that it
depends on TRUSTED_KEYS && TRUSTED_KEYS_TPM
The latter to ensure the dependency is built and the former to ensure
it's reachable for module builds. There are no such users yet.
Reviewed-by: Sumit Garg <sumit.garg@linaro.org>
Reviewed-by: Jarkko Sakkinen <jarkko@kernel.org>
Reviewed-by: Pankaj Gupta <pankaj.gupta@nxp.com>
Tested-by: Pankaj Gupta <pankaj.gupta@nxp.com>
Tested-by: Andreas Rammhold <andreas@rammhold.de>
Tested-by: Tim Harvey <tharvey@gateworks.com>
Tested-by: Michael Walle <michael@walle.cc> # on ls1028a (non-E and E)
Tested-by: John Ernberg <john.ernberg@actia.se> # iMX8QXP
Signed-off-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
Signed-off-by: Jarkko Sakkinen <jarkko@kernel.org>
4.7 KiB
SPDX-License-Identifier: GPL-2.0-only
Key management configuration
config KEYS bool "Enable access key retention support" select ASSOCIATIVE_ARRAY help This option provides support for retaining authentication tokens and access keys in the kernel.
It also includes provision of methods by which such keys might be
associated with a process so that network filesystems, encryption
support and the like can find them.
Furthermore, a special type of key is available that acts as keyring:
a searchable sequence of keys. Each process is equipped with access
to five standard keyrings: UID-specific, GID-specific, session,
process and thread.
If you are unsure as to whether this is required, answer N.
config KEYS_REQUEST_CACHE bool "Enable temporary caching of the last request_key() result" depends on KEYS help This option causes the result of the last successful request_key() call that didn't upcall to the kernel to be cached temporarily in the task_struct. The cache is cleared by exit and just prior to the resumption of userspace.
This allows the key used for multiple step processes where each step
wants to request a key that is likely the same as the one requested
by the last step to save on the searching.
An example of such a process is a pathwalk through a network
filesystem in which each method needs to request an authentication
key. Pathwalk will call multiple methods for each dentry traversed
(permission, d_revalidate, lookup, getxattr, getacl, ...).
config PERSISTENT_KEYRINGS bool "Enable register of persistent per-UID keyrings" depends on KEYS help This option provides a register of persistent per-UID keyrings, primarily aimed at Kerberos key storage. The keyrings are persistent in the sense that they stay around after all processes of that UID have exited, not that they survive the machine being rebooted.
A particular keyring may be accessed by either the user whose keyring
it is or by a process with administrative privileges. The active
LSMs gets to rule on which admin-level processes get to access the
cache.
Keyrings are created and added into the register upon demand and get
removed if they expire (a default timeout is set upon creation).
config BIG_KEYS bool "Large payload keys" depends on KEYS depends on TMPFS depends on CRYPTO_LIB_CHACHA20POLY1305 = y help This option provides support for holding large keys within the kernel (for example Kerberos ticket caches). The data may be stored out to swapspace by tmpfs.
If you are unsure as to whether this is required, answer N.
config TRUSTED_KEYS tristate "TRUSTED KEYS" depends on KEYS help This option provides support for creating, sealing, and unsealing keys in the kernel. Trusted keys are random number symmetric keys, generated and sealed by a trust source selected at kernel boot-time. Userspace will only ever see encrypted blobs.
If you are unsure as to whether this is required, answer N.
if TRUSTED_KEYS source "security/keys/trusted-keys/Kconfig" endif
config ENCRYPTED_KEYS tristate "ENCRYPTED KEYS" depends on KEYS select CRYPTO select CRYPTO_HMAC select CRYPTO_AES select CRYPTO_CBC select CRYPTO_SHA256 select CRYPTO_RNG help This option provides support for create/encrypting/decrypting keys in the kernel. Encrypted keys are instantiated using kernel generated random numbers or provided decrypted data, and are encrypted/decrypted with a 'master' symmetric key. The 'master' key can be either a trusted-key or user-key type. Only encrypted blobs are ever output to Userspace.
If you are unsure as to whether this is required, answer N.
config USER_DECRYPTED_DATA bool "Allow encrypted keys with user decrypted data" depends on ENCRYPTED_KEYS help This option provides support for instantiating encrypted keys using user-provided decrypted data. The decrypted data must be hex-ascii encoded.
If you are unsure as to whether this is required, answer N.
config KEY_DH_OPERATIONS bool "Diffie-Hellman operations on retained keys" depends on KEYS select CRYPTO select CRYPTO_KDF800108_CTR select CRYPTO_DH help This option provides support for calculating Diffie-Hellman public keys and shared secrets using values stored as keys in the kernel.
If you are unsure as to whether this is required, answer N.
config KEY_NOTIFICATIONS bool "Provide key/keyring change notifications" depends on KEYS && WATCH_QUEUE help This option provides support for getting change notifications on keys and keyrings on which the caller has View permission. This makes use of pipes to handle the notification buffer and provides KEYCTL_WATCH_KEY to enable/disable watches.