audit: document /proc/PID/loginuid

Describe the /proc/PID/loginuid interface in Documentation/ABI/stable that
was added 2005-02-01 by commit 1e2d1492e178 ("[PATCH] audit: handle
loginuid through proc")

Signed-off-by: Richard Guy Briggs <rgb@redhat.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>

Author: rgbriggs

Documentation/ABI/stable/procfs-audit_loginuid

@@ -0,0 +1,15 @@
+What:		Audit Login UID
+Date:		2005-02-01
+KernelVersion:	2.6.11-rc2 1e2d1492e178 ("[PATCH] audit: handle loginuid through proc")
+Contact:	linux-audit@redhat.com
+Format:		%u
+Users:		audit and login applications
+Description:
+		The /proc/$pid/loginuid pseudofile is written to set and
+		read to get the audit login UID of process $pid.  If it is
+		unset, permissions are not needed to set it.  The accessor must
+		have CAP_AUDIT_CONTROL in the initial user namespace to write
+		it if it has been set.  It cannot be written again if
+		AUDIT_FEATURE_LOGINUID_IMMUTABLE is enabled.  It cannot be
+		unset if AUDIT_FEATURE_ONLY_UNSET_LOGINUID is enabled.
+