521fd61c84
A while back, I noticed that the crypto and crypto API usage in big_keys were entirely broken in multiple ways, so I rewrote it. Now, I'm rewriting it again, but this time using the simpler ChaCha20Poly1305 library function. This makes the file considerably more simple; the diffstat alone should justify this commit. It also should be faster, since it no longer requires a mutex around the "aead api object" (nor allocations), allowing us to encrypt multiple items in parallel. We also benefit from being able to pass any type of pointer, so we can get rid of the ridiculously complex custom page allocator that big_key really doesn't need. [DH: Change the select CRYPTO_LIB_CHACHA20POLY1305 to a depends on as select doesn't propagate and the build can end up with an =y dependending on some =m pieces. The depends on CRYPTO also had to be removed otherwise the configurator complains about a recursive dependency.] Cc: Andy Lutomirski <luto@kernel.org> Cc: Greg KH <gregkh@linuxfoundation.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: kernel-hardening@lists.openwall.com Reviewed-by: Eric Biggers <ebiggers@google.com> Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com> Signed-off-by: David Howells <dhowells@redhat.com>
117 lines
4.1 KiB
Plaintext
117 lines
4.1 KiB
Plaintext
# 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 && TCG_TPM
|
|
select CRYPTO
|
|
select CRYPTO_HMAC
|
|
select CRYPTO_SHA1
|
|
select CRYPTO_HASH_INFO
|
|
help
|
|
This option provides support for creating, sealing, and unsealing
|
|
keys in the kernel. Trusted keys are random number symmetric keys,
|
|
generated and RSA-sealed by the TPM. The TPM only unseals the keys,
|
|
if the boot PCRs and other criteria match. Userspace will only ever
|
|
see encrypted blobs.
|
|
|
|
If you are unsure as to whether this is required, answer N.
|
|
|
|
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 kernel generated random numbers,
|
|
which are encrypted/decrypted with a 'master' symmetric key. The
|
|
'master' key can be either a trusted-key or user-key type.
|
|
Userspace only ever sees/stores encrypted blobs.
|
|
|
|
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_HASH
|
|
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.
|