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-rw-r--r--Documentation/keys.txt39
1 files changed, 38 insertions, 1 deletions
diff --git a/Documentation/keys.txt b/Documentation/keys.txt
index b56aacc1fff..e4dbbdb1bd9 100644
--- a/Documentation/keys.txt
+++ b/Documentation/keys.txt
@@ -26,7 +26,7 @@ This document has the following sections:
- Notes on accessing payload contents
- Defining a key type
- Request-key callback service
- - Key access filesystem
+ - Garbage collection
============
@@ -113,6 +113,9 @@ Each key has a number of attributes:
(*) Dead. The key's type was unregistered, and so the key is now useless.
+Keys in the last three states are subject to garbage collection. See the
+section on "Garbage collection".
+
====================
KEY SERVICE OVERVIEW
@@ -754,6 +757,26 @@ The keyctl syscall functions are:
successful.
+ (*) Install the calling process's session keyring on its parent.
+
+ long keyctl(KEYCTL_SESSION_TO_PARENT);
+
+ This functions attempts to install the calling process's session keyring
+ on to the calling process's parent, replacing the parent's current session
+ keyring.
+
+ The calling process must have the same ownership as its parent, the
+ keyring must have the same ownership as the calling process, the calling
+ process must have LINK permission on the keyring and the active LSM module
+ mustn't deny permission, otherwise error EPERM will be returned.
+
+ Error ENOMEM will be returned if there was insufficient memory to complete
+ the operation, otherwise 0 will be returned to indicate success.
+
+ The keyring will be replaced next time the parent process leaves the
+ kernel and resumes executing userspace.
+
+
===============
KERNEL SERVICES
===============
@@ -1231,3 +1254,17 @@ by executing:
In this case, the program isn't required to actually attach the key to a ring;
the rings are provided for reference.
+
+
+==================
+GARBAGE COLLECTION
+==================
+
+Dead keys (for which the type has been removed) will be automatically unlinked
+from those keyrings that point to them and deleted as soon as possible by a
+background garbage collector.
+
+Similarly, revoked and expired keys will be garbage collected, but only after a
+certain amount of time has passed. This time is set as a number of seconds in:
+
+ /proc/sys/kernel/keys/gc_delay