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-rw-r--r--Documentation/keys.txt39
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diff --git a/Documentation/keys.txt b/Documentation/keys.txt
index aaa01b0e3ee9..3bbe157b45e4 100644
--- a/Documentation/keys.txt
+++ b/Documentation/keys.txt
@@ -19,6 +19,7 @@ This document has the following sections:
- Key overview
- Key service overview
- Key access permissions
+ - SELinux support
- New procfs files
- Userspace system call interface
- Kernel services
@@ -232,6 +233,34 @@ For changing the ownership, group ID or permissions mask, being the owner of
the key or having the sysadmin capability is sufficient.
+===============
+SELINUX SUPPORT
+===============
+
+The security class "key" has been added to SELinux so that mandatory access
+controls can be applied to keys created within various contexts. This support
+is preliminary, and is likely to change quite significantly in the near future.
+Currently, all of the basic permissions explained above are provided in SELinux
+as well; SE Linux is simply invoked after all basic permission checks have been
+performed.
+
+Each key is labeled with the same context as the task to which it belongs.
+Typically, this is the same task that was running when the key was created.
+The default keyrings are handled differently, but in a way that is very
+intuitive:
+
+ (*) The user and user session keyrings that are created when the user logs in
+ are currently labeled with the context of the login manager.
+
+ (*) The keyrings associated with new threads are each labeled with the context
+ of their associated thread, and both session and process keyrings are
+ handled similarly.
+
+Note, however, that the default keyrings associated with the root user are
+labeled with the default kernel context, since they are created early in the
+boot process, before root has a chance to log in.
+
+
================
NEW PROCFS FILES
================
@@ -935,6 +964,16 @@ The structure has a number of fields, some of which are mandatory:
It is not safe to sleep in this method; the caller may hold spinlocks.
+ (*) void (*revoke)(struct key *key);
+
+ This method is optional. It is called to discard part of the payload
+ data upon a key being revoked. The caller will have the key semaphore
+ write-locked.
+
+ It is safe to sleep in this method, though care should be taken to avoid
+ a deadlock against the key semaphore.
+
+
(*) void (*destroy)(struct key *key);
This method is optional. It is called to discard the payload data on a key