KEYS: Allow special keyrings to be cleared
The kernel contains some special internal keyrings, for instance the DNS
resolver keyring :
2a93faf1 I----- 1 perm 1f030000 0 0 keyring .dns_resolver: empty
It would occasionally be useful to allow the contents of such keyrings to be
flushed by root (cache invalidation).
Allow a flag to be set on a keyring to mark that someone possessing the
sysadmin capability can clear the keyring, even without normal write access to
the keyring.
Set this flag on the special keyrings created by the DNS resolver, the NFS
identity mapper and the CIFS identity mapper.
Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Jeff Layton <jlayton@redhat.com>
Acked-by: Steve Dickson <steved@redhat.com>
Signed-off-by: James Morris <jmorris@namei.org>
diff --git a/Documentation/networking/dns_resolver.txt b/Documentation/networking/dns_resolver.txt
index 7f531ad..d86adcd 100644
--- a/Documentation/networking/dns_resolver.txt
+++ b/Documentation/networking/dns_resolver.txt
@@ -102,6 +102,10 @@
If _expiry is non-NULL, the expiry time (TTL) of the result will be
returned also.
+The kernel maintains an internal keyring in which it caches looked up keys.
+This can be cleared by any process that has the CAP_SYS_ADMIN capability by
+the use of KEYCTL_KEYRING_CLEAR on the keyring ID.
+
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READING DNS KEYS FROM USERSPACE