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authorDavid Howells <dhowells@redhat.com>2012-01-18 15:31:45 +0000
committerJames Morris <jmorris@namei.org>2012-01-19 14:38:51 +1100
commit700920eb5ba4de5417b446c9a8bb008df2b973e0 (patch)
tree8e2caa32a5cdcd47347ff84bc3e95915d000f537 /security/keys/keyctl.c
parent53999bf34d55981328f8ba9def558d3e104d6e36 (diff)
downloadlinaro-lsk-700920eb5ba4de5417b446c9a8bb008df2b973e0.tar.gz
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>
Diffstat (limited to 'security/keys/keyctl.c')
-rw-r--r--security/keys/keyctl.c15
1 files changed, 14 insertions, 1 deletions
diff --git a/security/keys/keyctl.c b/security/keys/keyctl.c
index 0b3f5d72af1..6523599e9ac 100644
--- a/security/keys/keyctl.c
+++ b/security/keys/keyctl.c
@@ -388,11 +388,24 @@ long keyctl_keyring_clear(key_serial_t ringid)
keyring_ref = lookup_user_key(ringid, KEY_LOOKUP_CREATE, KEY_WRITE);
if (IS_ERR(keyring_ref)) {
ret = PTR_ERR(keyring_ref);
+
+ /* Root is permitted to invalidate certain special keyrings */
+ if (capable(CAP_SYS_ADMIN)) {
+ keyring_ref = lookup_user_key(ringid, 0, 0);
+ if (IS_ERR(keyring_ref))
+ goto error;
+ if (test_bit(KEY_FLAG_ROOT_CAN_CLEAR,
+ &key_ref_to_ptr(keyring_ref)->flags))
+ goto clear;
+ goto error_put;
+ }
+
goto error;
}
+clear:
ret = keyring_clear(key_ref_to_ptr(keyring_ref));
-
+error_put:
key_ref_put(keyring_ref);
error:
return ret;