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authorAndy Adamson <andros@netapp.com>2013-08-14 11:59:15 -0400
committerTrond Myklebust <Trond.Myklebust@netapp.com>2013-09-03 15:25:08 -0400
commit4de6caa270afaa381dd3373e9e6d148b1090e0ec (patch)
tree2b212167c872f2038ed3480df872766bbd7b67e3 /net/sunrpc/auth_generic.c
parentf1ff0c27fd9987c59d707cd1a6b6c1fc3ae0a250 (diff)
downloadlinux-4de6caa270afaa381dd3373e9e6d148b1090e0ec.tar.gz
SUNRPC new rpc_credops to test credential expiry
This patch provides the RPC layer helper functions to allow NFS to manage data in the face of expired credentials - such as avoiding buffered WRITEs and COMMITs when the gss context will expire before the WRITEs are flushed and COMMITs are sent. These helper functions enable checking the expiration of an underlying credential key for a generic rpc credential, e.g. the gss_cred gss context gc_expiry which for Kerberos is set to the remaining TGT lifetime. A new rpc_authops key_timeout is only defined for the generic auth. A new rpc_credops crkey_to_expire is only defined for the generic cred. A new rpc_credops crkey_timeout is only defined for the gss cred. Set a credential key expiry watermark, RPC_KEY_EXPIRE_TIMEO set to 240 seconds as a default and can be set via a module parameter as we need to ensure there is time for any dirty data to be flushed. If key_timeout is called on a credential with an underlying credential key that will expire within watermark seconds, we set the RPC_CRED_KEY_EXPIRE_SOON flag in the generic_cred acred so that the NFS layer can clean up prior to key expiration. Checking a generic credential's underlying credential involves a cred lookup. To avoid this lookup in the normal case when the underlying credential has a key that is valid (before the watermark), a notify flag is set in the generic credential the first time the key_timeout is called. The generic credential then stops checking the underlying credential key expiry, and the underlying credential (gss_cred) match routine then checks the key expiration upon each normal use and sets a flag in the associated generic credential only when the key expiration is within the watermark. This in turn signals the generic credential key_timeout to perform the extra credential lookup thereafter. Signed-off-by: Andy Adamson <andros@netapp.com> Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Diffstat (limited to 'net/sunrpc/auth_generic.c')
-rw-r--r--net/sunrpc/auth_generic.c82
1 files changed, 82 insertions, 0 deletions
diff --git a/net/sunrpc/auth_generic.c b/net/sunrpc/auth_generic.c
index b6badafc649..f6d84be4905 100644
--- a/net/sunrpc/auth_generic.c
+++ b/net/sunrpc/auth_generic.c
@@ -89,6 +89,7 @@ generic_create_cred(struct rpc_auth *auth, struct auth_cred *acred, int flags)
gcred->acred.uid = acred->uid;
gcred->acred.gid = acred->gid;
gcred->acred.group_info = acred->group_info;
+ gcred->acred.ac_flags = 0;
if (gcred->acred.group_info != NULL)
get_group_info(gcred->acred.group_info);
gcred->acred.machine_cred = acred->machine_cred;
@@ -182,11 +183,78 @@ void rpc_destroy_generic_auth(void)
rpcauth_destroy_credcache(&generic_auth);
}
+/*
+ * Test the the current time (now) against the underlying credential key expiry
+ * minus a timeout and setup notification.
+ *
+ * The normal case:
+ * If 'now' is before the key expiry minus RPC_KEY_EXPIRE_TIMEO, set
+ * the RPC_CRED_NOTIFY_TIMEOUT flag to setup the underlying credential
+ * rpc_credops crmatch routine to notify this generic cred when it's key
+ * expiration is within RPC_KEY_EXPIRE_TIMEO, and return 0.
+ *
+ * The error case:
+ * If the underlying cred lookup fails, return -EACCES.
+ *
+ * The 'almost' error case:
+ * If 'now' is within key expiry minus RPC_KEY_EXPIRE_TIMEO, but not within
+ * key expiry minus RPC_KEY_EXPIRE_FAIL, set the RPC_CRED_EXPIRE_SOON bit
+ * on the acred ac_flags and return 0.
+ */
+static int
+generic_key_timeout(struct rpc_auth *auth, struct rpc_cred *cred)
+{
+ struct auth_cred *acred = &container_of(cred, struct generic_cred,
+ gc_base)->acred;
+ struct rpc_cred *tcred;
+ int ret = 0;
+
+
+ /* Fast track for non crkey_timeout (no key) underlying credentials */
+ if (test_bit(RPC_CRED_NO_CRKEY_TIMEOUT, &acred->ac_flags))
+ return 0;
+
+ /* Fast track for the normal case */
+ if (test_bit(RPC_CRED_NOTIFY_TIMEOUT, &acred->ac_flags))
+ return 0;
+
+ /* lookup_cred either returns a valid referenced rpc_cred, or PTR_ERR */
+ tcred = auth->au_ops->lookup_cred(auth, acred, 0);
+ if (IS_ERR(tcred))
+ return -EACCES;
+
+ if (!tcred->cr_ops->crkey_timeout) {
+ set_bit(RPC_CRED_NO_CRKEY_TIMEOUT, &acred->ac_flags);
+ ret = 0;
+ goto out_put;
+ }
+
+ /* Test for the almost error case */
+ ret = tcred->cr_ops->crkey_timeout(tcred);
+ if (ret != 0) {
+ set_bit(RPC_CRED_KEY_EXPIRE_SOON, &acred->ac_flags);
+ ret = 0;
+ } else {
+ /* In case underlying cred key has been reset */
+ if (test_and_clear_bit(RPC_CRED_KEY_EXPIRE_SOON,
+ &acred->ac_flags))
+ dprintk("RPC: UID %d Credential key reset\n",
+ tcred->cr_uid);
+ /* set up fasttrack for the normal case */
+ set_bit(RPC_CRED_NOTIFY_TIMEOUT, &acred->ac_flags);
+ }
+
+out_put:
+ put_rpccred(tcred);
+ return ret;
+}
+
static const struct rpc_authops generic_auth_ops = {
.owner = THIS_MODULE,
.au_name = "Generic",
.lookup_cred = generic_lookup_cred,
.crcreate = generic_create_cred,
+ .key_timeout = generic_key_timeout,
};
static struct rpc_auth generic_auth = {
@@ -194,9 +262,23 @@ static struct rpc_auth generic_auth = {
.au_count = ATOMIC_INIT(0),
};
+static bool generic_key_to_expire(struct rpc_cred *cred)
+{
+ struct auth_cred *acred = &container_of(cred, struct generic_cred,
+ gc_base)->acred;
+ bool ret;
+
+ get_rpccred(cred);
+ ret = test_bit(RPC_CRED_KEY_EXPIRE_SOON, &acred->ac_flags);
+ put_rpccred(cred);
+
+ return ret;
+}
+
static const struct rpc_credops generic_credops = {
.cr_name = "Generic cred",
.crdestroy = generic_destroy_cred,
.crbind = generic_bind_cred,
.crmatch = generic_match,
+ .crkey_to_expire = generic_key_to_expire,
};