linux-sg2042/security/keys/Kconfig

83 lines
2.8 KiB
Plaintext
Raw Normal View History

#
# 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.
KEYS: Add per-user_namespace registers for persistent per-UID kerberos caches Add support for per-user_namespace registers of persistent per-UID kerberos caches held within the kernel. This allows the kerberos cache to be retained beyond the life of all a user's processes so that the user's cron jobs can work. The kerberos cache is envisioned as a keyring/key tree looking something like: struct user_namespace \___ .krb_cache keyring - The register \___ _krb.0 keyring - Root's Kerberos cache \___ _krb.5000 keyring - User 5000's Kerberos cache \___ _krb.5001 keyring - User 5001's Kerberos cache \___ tkt785 big_key - A ccache blob \___ tkt12345 big_key - Another ccache blob Or possibly: struct user_namespace \___ .krb_cache keyring - The register \___ _krb.0 keyring - Root's Kerberos cache \___ _krb.5000 keyring - User 5000's Kerberos cache \___ _krb.5001 keyring - User 5001's Kerberos cache \___ tkt785 keyring - A ccache \___ krbtgt/REDHAT.COM@REDHAT.COM big_key \___ http/REDHAT.COM@REDHAT.COM user \___ afs/REDHAT.COM@REDHAT.COM user \___ nfs/REDHAT.COM@REDHAT.COM user \___ krbtgt/KERNEL.ORG@KERNEL.ORG big_key \___ http/KERNEL.ORG@KERNEL.ORG big_key What goes into a particular Kerberos cache is entirely up to userspace. Kernel support is limited to giving you the Kerberos cache keyring that you want. The user asks for their Kerberos cache by: krb_cache = keyctl_get_krbcache(uid, dest_keyring); The uid is -1 or the user's own UID for the user's own cache or the uid of some other user's cache (requires CAP_SETUID). This permits rpc.gssd or whatever to mess with the cache. The cache returned is a keyring named "_krb.<uid>" that the possessor can read, search, clear, invalidate, unlink from and add links to. Active LSMs get a chance to rule on whether the caller is permitted to make a link. Each uid's cache keyring is created when it first accessed and is given a timeout that is extended each time this function is called so that the keyring goes away after a while. The timeout is configurable by sysctl but defaults to three days. Each user_namespace struct gets a lazily-created keyring that serves as the register. The cache keyrings are added to it. This means that standard key search and garbage collection facilities are available. The user_namespace struct's register goes away when it does and anything left in it is then automatically gc'd. Signed-off-by: David Howells <dhowells@redhat.com> Tested-by: Simo Sorce <simo@redhat.com> cc: Serge E. Hallyn <serge.hallyn@ubuntu.com> cc: Eric W. Biederman <ebiederm@xmission.com>
2013-09-24 17:35:19 +08:00
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
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
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.