keys: update the documentation with info about "logon" keys
Acked-by: David Howells <dhowells@redhat.com>
Signed-off-by: Jeff Layton <jlayton@redhat.com>
diff --git a/Documentation/security/keys.txt b/Documentation/security/keys.txt
index 7877170..d389acd 100644
--- a/Documentation/security/keys.txt
+++ b/Documentation/security/keys.txt
@@ -123,7 +123,7 @@
The key service provides a number of features besides keys:
- (*) The key service defines two special key types:
+ (*) The key service defines three special key types:
(+) "keyring"
@@ -137,6 +137,18 @@
blobs of data. These can be created, updated and read by userspace,
and aren't intended for use by kernel services.
+ (+) "logon"
+
+ Like a "user" key, a "logon" key has a payload that is an arbitrary
+ blob of data. It is intended as a place to store secrets which are
+ accessible to the kernel but not to userspace programs.
+
+ The description can be arbitrary, but must be prefixed with a non-zero
+ length string that describes the key "subclass". The subclass is
+ separated from the rest of the description by a ':'. "logon" keys can
+ be created and updated from userspace, but the payload is only
+ readable from kernel space.
+
(*) Each process subscribes to three keyrings: a thread-specific keyring, a
process-specific keyring, and a session-specific keyring.