Adding upstream version 6.6.15.upstream/6.6.15

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 893 insertions, 0 deletions

diff --git a/net/sunrpc/auth.c b/net/sunrpc/auth.c
new file mode 100644
index 0000000000..ec41b26af7
--- /dev/null
+++ b/net/sunrpc/auth.c
@@ -0,0 +1,893 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * linux/net/sunrpc/auth.c
+ *
+ * Generic RPC client authentication API.
+ *
+ * Copyright (C) 1996, Olaf Kirch <okir@monad.swb.de>
+ */
+
+#include <linux/types.h>
+#include <linux/sched.h>
+#include <linux/cred.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/errno.h>
+#include <linux/hash.h>
+#include <linux/sunrpc/clnt.h>
+#include <linux/sunrpc/gss_api.h>
+#include <linux/spinlock.h>
+
+#include <trace/events/sunrpc.h>
+
+#define RPC_CREDCACHE_DEFAULT_HASHBITS	(4)
+struct rpc_cred_cache {
+	struct hlist_head	*hashtable;
+	unsigned int		hashbits;
+	spinlock_t		lock;
+};
+
+static unsigned int auth_hashbits = RPC_CREDCACHE_DEFAULT_HASHBITS;
+
+static const struct rpc_authops __rcu *auth_flavors[RPC_AUTH_MAXFLAVOR] = {
+	[RPC_AUTH_NULL] = (const struct rpc_authops __force __rcu *)&authnull_ops,
+	[RPC_AUTH_UNIX] = (const struct rpc_authops __force __rcu *)&authunix_ops,
+	[RPC_AUTH_TLS]  = (const struct rpc_authops __force __rcu *)&authtls_ops,
+};
+
+static LIST_HEAD(cred_unused);
+static unsigned long number_cred_unused;
+
+static struct cred machine_cred = {
+	.usage = ATOMIC_INIT(1),
+};
+
+/*
+ * Return the machine_cred pointer to be used whenever
+ * the a generic machine credential is needed.
+ */
+const struct cred *rpc_machine_cred(void)
+{
+	return &machine_cred;
+}
+EXPORT_SYMBOL_GPL(rpc_machine_cred);
+
+#define MAX_HASHTABLE_BITS (14)
+static int param_set_hashtbl_sz(const char *val, const struct kernel_param *kp)
+{
+	unsigned long num;
+	unsigned int nbits;
+	int ret;
+
+	if (!val)
+		goto out_inval;
+	ret = kstrtoul(val, 0, &num);
+	if (ret)
+		goto out_inval;
+	nbits = fls(num - 1);
+	if (nbits > MAX_HASHTABLE_BITS || nbits < 2)
+		goto out_inval;
+	*(unsigned int *)kp->arg = nbits;
+	return 0;
+out_inval:
+	return -EINVAL;
+}
+
+static int param_get_hashtbl_sz(char *buffer, const struct kernel_param *kp)
+{
+	unsigned int nbits;
+
+	nbits = *(unsigned int *)kp->arg;
+	return sprintf(buffer, "%u\n", 1U << nbits);
+}
+
+#define param_check_hashtbl_sz(name, p) __param_check(name, p, unsigned int);
+
+static const struct kernel_param_ops param_ops_hashtbl_sz = {
+	.set = param_set_hashtbl_sz,
+	.get = param_get_hashtbl_sz,
+};
+
+module_param_named(auth_hashtable_size, auth_hashbits, hashtbl_sz, 0644);
+MODULE_PARM_DESC(auth_hashtable_size, "RPC credential cache hashtable size");
+
+static unsigned long auth_max_cred_cachesize = ULONG_MAX;
+module_param(auth_max_cred_cachesize, ulong, 0644);
+MODULE_PARM_DESC(auth_max_cred_cachesize, "RPC credential maximum total cache size");
+
+static u32
+pseudoflavor_to_flavor(u32 flavor) {
+	if (flavor > RPC_AUTH_MAXFLAVOR)
+		return RPC_AUTH_GSS;
+	return flavor;
+}
+
+int
+rpcauth_register(const struct rpc_authops *ops)
+{
+	const struct rpc_authops *old;
+	rpc_authflavor_t flavor;
+
+	if ((flavor = ops->au_flavor) >= RPC_AUTH_MAXFLAVOR)
+		return -EINVAL;
+	old = cmpxchg((const struct rpc_authops ** __force)&auth_flavors[flavor], NULL, ops);
+	if (old == NULL || old == ops)
+		return 0;
+	return -EPERM;
+}
+EXPORT_SYMBOL_GPL(rpcauth_register);
+
+int
+rpcauth_unregister(const struct rpc_authops *ops)
+{
+	const struct rpc_authops *old;
+	rpc_authflavor_t flavor;
+
+	if ((flavor = ops->au_flavor) >= RPC_AUTH_MAXFLAVOR)
+		return -EINVAL;
+
+	old = cmpxchg((const struct rpc_authops ** __force)&auth_flavors[flavor], ops, NULL);
+	if (old == ops || old == NULL)
+		return 0;
+	return -EPERM;
+}
+EXPORT_SYMBOL_GPL(rpcauth_unregister);
+
+static const struct rpc_authops *
+rpcauth_get_authops(rpc_authflavor_t flavor)
+{
+	const struct rpc_authops *ops;
+
+	if (flavor >= RPC_AUTH_MAXFLAVOR)
+		return NULL;
+
+	rcu_read_lock();
+	ops = rcu_dereference(auth_flavors[flavor]);
+	if (ops == NULL) {
+		rcu_read_unlock();
+		request_module("rpc-auth-%u", flavor);
+		rcu_read_lock();
+		ops = rcu_dereference(auth_flavors[flavor]);
+		if (ops == NULL)
+			goto out;
+	}
+	if (!try_module_get(ops->owner))
+		ops = NULL;
+out:
+	rcu_read_unlock();
+	return ops;
+}
+
+static void
+rpcauth_put_authops(const struct rpc_authops *ops)
+{
+	module_put(ops->owner);
+}
+
+/**
+ * rpcauth_get_pseudoflavor - check if security flavor is supported
+ * @flavor: a security flavor
+ * @info: a GSS mech OID, quality of protection, and service value
+ *
+ * Verifies that an appropriate kernel module is available or already loaded.
+ * Returns an equivalent pseudoflavor, or RPC_AUTH_MAXFLAVOR if "flavor" is
+ * not supported locally.
+ */
+rpc_authflavor_t
+rpcauth_get_pseudoflavor(rpc_authflavor_t flavor, struct rpcsec_gss_info *info)
+{
+	const struct rpc_authops *ops = rpcauth_get_authops(flavor);
+	rpc_authflavor_t pseudoflavor;
+
+	if (!ops)
+		return RPC_AUTH_MAXFLAVOR;
+	pseudoflavor = flavor;
+	if (ops->info2flavor != NULL)
+		pseudoflavor = ops->info2flavor(info);
+
+	rpcauth_put_authops(ops);
+	return pseudoflavor;
+}
+EXPORT_SYMBOL_GPL(rpcauth_get_pseudoflavor);
+
+/**
+ * rpcauth_get_gssinfo - find GSS tuple matching a GSS pseudoflavor
+ * @pseudoflavor: GSS pseudoflavor to match
+ * @info: rpcsec_gss_info structure to fill in
+ *
+ * Returns zero and fills in "info" if pseudoflavor matches a
+ * supported mechanism.
+ */
+int
+rpcauth_get_gssinfo(rpc_authflavor_t pseudoflavor, struct rpcsec_gss_info *info)
+{
+	rpc_authflavor_t flavor = pseudoflavor_to_flavor(pseudoflavor);
+	const struct rpc_authops *ops;
+	int result;
+
+	ops = rpcauth_get_authops(flavor);
+	if (ops == NULL)
+		return -ENOENT;
+
+	result = -ENOENT;
+	if (ops->flavor2info != NULL)
+		result = ops->flavor2info(pseudoflavor, info);
+
+	rpcauth_put_authops(ops);
+	return result;
+}
+EXPORT_SYMBOL_GPL(rpcauth_get_gssinfo);
+
+struct rpc_auth *
+rpcauth_create(const struct rpc_auth_create_args *args, struct rpc_clnt *clnt)
+{
+	struct rpc_auth	*auth = ERR_PTR(-EINVAL);
+	const struct rpc_authops *ops;
+	u32 flavor = pseudoflavor_to_flavor(args->pseudoflavor);
+
+	ops = rpcauth_get_authops(flavor);
+	if (ops == NULL)
+		goto out;
+
+	auth = ops->create(args, clnt);
+
+	rpcauth_put_authops(ops);
+	if (IS_ERR(auth))
+		return auth;
+	if (clnt->cl_auth)
+		rpcauth_release(clnt->cl_auth);
+	clnt->cl_auth = auth;
+
+out:
+	return auth;
+}
+EXPORT_SYMBOL_GPL(rpcauth_create);
+
+void
+rpcauth_release(struct rpc_auth *auth)
+{
+	if (!refcount_dec_and_test(&auth->au_count))
+		return;
+	auth->au_ops->destroy(auth);
+}
+
+static DEFINE_SPINLOCK(rpc_credcache_lock);
+
+/*
+ * On success, the caller is responsible for freeing the reference
+ * held by the hashtable
+ */
+static bool
+rpcauth_unhash_cred_locked(struct rpc_cred *cred)
+{
+	if (!test_and_clear_bit(RPCAUTH_CRED_HASHED, &cred->cr_flags))
+		return false;
+	hlist_del_rcu(&cred->cr_hash);
+	return true;
+}
+
+static bool
+rpcauth_unhash_cred(struct rpc_cred *cred)
+{
+	spinlock_t *cache_lock;
+	bool ret;
+
+	if (!test_bit(RPCAUTH_CRED_HASHED, &cred->cr_flags))
+		return false;
+	cache_lock = &cred->cr_auth->au_credcache->lock;
+	spin_lock(cache_lock);
+	ret = rpcauth_unhash_cred_locked(cred);
+	spin_unlock(cache_lock);
+	return ret;
+}
+
+/*
+ * Initialize RPC credential cache
+ */
+int
+rpcauth_init_credcache(struct rpc_auth *auth)
+{
+	struct rpc_cred_cache *new;
+	unsigned int hashsize;
+
+	new = kmalloc(sizeof(*new), GFP_KERNEL);
+	if (!new)
+		goto out_nocache;
+	new->hashbits = auth_hashbits;
+	hashsize = 1U << new->hashbits;
+	new->hashtable = kcalloc(hashsize, sizeof(new->hashtable[0]), GFP_KERNEL);
+	if (!new->hashtable)
+		goto out_nohashtbl;
+	spin_lock_init(&new->lock);
+	auth->au_credcache = new;
+	return 0;
+out_nohashtbl:
+	kfree(new);
+out_nocache:
+	return -ENOMEM;
+}
+EXPORT_SYMBOL_GPL(rpcauth_init_credcache);
+
+char *
+rpcauth_stringify_acceptor(struct rpc_cred *cred)
+{
+	if (!cred->cr_ops->crstringify_acceptor)
+		return NULL;
+	return cred->cr_ops->crstringify_acceptor(cred);
+}
+EXPORT_SYMBOL_GPL(rpcauth_stringify_acceptor);
+
+/*
+ * Destroy a list of credentials
+ */
+static inline
+void rpcauth_destroy_credlist(struct list_head *head)
+{
+	struct rpc_cred *cred;
+
+	while (!list_empty(head)) {
+		cred = list_entry(head->next, struct rpc_cred, cr_lru);
+		list_del_init(&cred->cr_lru);
+		put_rpccred(cred);
+	}
+}
+
+static void
+rpcauth_lru_add_locked(struct rpc_cred *cred)
+{
+	if (!list_empty(&cred->cr_lru))
+		return;
+	number_cred_unused++;
+	list_add_tail(&cred->cr_lru, &cred_unused);
+}
+
+static void
+rpcauth_lru_add(struct rpc_cred *cred)
+{
+	if (!list_empty(&cred->cr_lru))
+		return;
+	spin_lock(&rpc_credcache_lock);
+	rpcauth_lru_add_locked(cred);
+	spin_unlock(&rpc_credcache_lock);
+}
+
+static void
+rpcauth_lru_remove_locked(struct rpc_cred *cred)
+{
+	if (list_empty(&cred->cr_lru))
+		return;
+	number_cred_unused--;
+	list_del_init(&cred->cr_lru);
+}
+
+static void
+rpcauth_lru_remove(struct rpc_cred *cred)
+{
+	if (list_empty(&cred->cr_lru))
+		return;
+	spin_lock(&rpc_credcache_lock);
+	rpcauth_lru_remove_locked(cred);
+	spin_unlock(&rpc_credcache_lock);
+}
+
+/*
+ * Clear the RPC credential cache, and delete those credentials
+ * that are not referenced.
+ */
+void
+rpcauth_clear_credcache(struct rpc_cred_cache *cache)
+{
+	LIST_HEAD(free);
+	struct hlist_head *head;
+	struct rpc_cred	*cred;
+	unsigned int hashsize = 1U << cache->hashbits;
+	int		i;
+
+	spin_lock(&rpc_credcache_lock);
+	spin_lock(&cache->lock);
+	for (i = 0; i < hashsize; i++) {
+		head = &cache->hashtable[i];
+		while (!hlist_empty(head)) {
+			cred = hlist_entry(head->first, struct rpc_cred, cr_hash);
+			rpcauth_unhash_cred_locked(cred);
+			/* Note: We now hold a reference to cred */
+			rpcauth_lru_remove_locked(cred);
+			list_add_tail(&cred->cr_lru, &free);
+		}
+	}
+	spin_unlock(&cache->lock);
+	spin_unlock(&rpc_credcache_lock);
+	rpcauth_destroy_credlist(&free);
+}
+
+/*
+ * Destroy the RPC credential cache
+ */
+void
+rpcauth_destroy_credcache(struct rpc_auth *auth)
+{
+	struct rpc_cred_cache *cache = auth->au_credcache;
+
+	if (cache) {
+		auth->au_credcache = NULL;
+		rpcauth_clear_credcache(cache);
+		kfree(cache->hashtable);
+		kfree(cache);
+	}
+}
+EXPORT_SYMBOL_GPL(rpcauth_destroy_credcache);
+
+
+#define RPC_AUTH_EXPIRY_MORATORIUM (60 * HZ)
+
+/*
+ * Remove stale credentials. Avoid sleeping inside the loop.
+ */
+static long
+rpcauth_prune_expired(struct list_head *free, int nr_to_scan)
+{
+	struct rpc_cred *cred, *next;
+	unsigned long expired = jiffies - RPC_AUTH_EXPIRY_MORATORIUM;
+	long freed = 0;
+
+	list_for_each_entry_safe(cred, next, &cred_unused, cr_lru) {
+
+		if (nr_to_scan-- == 0)
+			break;
+		if (refcount_read(&cred->cr_count) > 1) {
+			rpcauth_lru_remove_locked(cred);
+			continue;
+		}
+		/*
+		 * Enforce a 60 second garbage collection moratorium
+		 * Note that the cred_unused list must be time-ordered.
+		 */
+		if (time_in_range(cred->cr_expire, expired, jiffies))
+			continue;
+		if (!rpcauth_unhash_cred(cred))
+			continue;
+
+		rpcauth_lru_remove_locked(cred);
+		freed++;
+		list_add_tail(&cred->cr_lru, free);
+	}
+	return freed ? freed : SHRINK_STOP;
+}
+
+static unsigned long
+rpcauth_cache_do_shrink(int nr_to_scan)
+{
+	LIST_HEAD(free);
+	unsigned long freed;
+
+	spin_lock(&rpc_credcache_lock);
+	freed = rpcauth_prune_expired(&free, nr_to_scan);
+	spin_unlock(&rpc_credcache_lock);
+	rpcauth_destroy_credlist(&free);
+
+	return freed;
+}
+
+/*
+ * Run memory cache shrinker.
+ */
+static unsigned long
+rpcauth_cache_shrink_scan(struct shrinker *shrink, struct shrink_control *sc)
+
+{
+	if ((sc->gfp_mask & GFP_KERNEL) != GFP_KERNEL)
+		return SHRINK_STOP;
+
+	/* nothing left, don't come back */
+	if (list_empty(&cred_unused))
+		return SHRINK_STOP;
+
+	return rpcauth_cache_do_shrink(sc->nr_to_scan);
+}
+
+static unsigned long
+rpcauth_cache_shrink_count(struct shrinker *shrink, struct shrink_control *sc)
+
+{
+	return number_cred_unused * sysctl_vfs_cache_pressure / 100;
+}
+
+static void
+rpcauth_cache_enforce_limit(void)
+{
+	unsigned long diff;
+	unsigned int nr_to_scan;
+
+	if (number_cred_unused <= auth_max_cred_cachesize)
+		return;
+	diff = number_cred_unused - auth_max_cred_cachesize;
+	nr_to_scan = 100;
+	if (diff < nr_to_scan)
+		nr_to_scan = diff;
+	rpcauth_cache_do_shrink(nr_to_scan);
+}
+
+/*
+ * Look up a process' credentials in the authentication cache
+ */
+struct rpc_cred *
+rpcauth_lookup_credcache(struct rpc_auth *auth, struct auth_cred * acred,
+		int flags, gfp_t gfp)
+{
+	LIST_HEAD(free);
+	struct rpc_cred_cache *cache = auth->au_credcache;
+	struct rpc_cred	*cred = NULL,
+			*entry, *new;
+	unsigned int nr;
+
+	nr = auth->au_ops->hash_cred(acred, cache->hashbits);
+
+	rcu_read_lock();
+	hlist_for_each_entry_rcu(entry, &cache->hashtable[nr], cr_hash) {
+		if (!entry->cr_ops->crmatch(acred, entry, flags))
+			continue;
+		cred = get_rpccred(entry);
+		if (cred)
+			break;
+	}
+	rcu_read_unlock();
+
+	if (cred != NULL)
+		goto found;
+
+	new = auth->au_ops->crcreate(auth, acred, flags, gfp);
+	if (IS_ERR(new)) {
+		cred = new;
+		goto out;
+	}
+
+	spin_lock(&cache->lock);
+	hlist_for_each_entry(entry, &cache->hashtable[nr], cr_hash) {
+		if (!entry->cr_ops->crmatch(acred, entry, flags))
+			continue;
+		cred = get_rpccred(entry);
+		if (cred)
+			break;
+	}
+	if (cred == NULL) {
+		cred = new;
+		set_bit(RPCAUTH_CRED_HASHED, &cred->cr_flags);
+		refcount_inc(&cred->cr_count);
+		hlist_add_head_rcu(&cred->cr_hash, &cache->hashtable[nr]);
+	} else
+		list_add_tail(&new->cr_lru, &free);
+	spin_unlock(&cache->lock);
+	rpcauth_cache_enforce_limit();
+found:
+	if (test_bit(RPCAUTH_CRED_NEW, &cred->cr_flags) &&
+	    cred->cr_ops->cr_init != NULL &&
+	    !(flags & RPCAUTH_LOOKUP_NEW)) {
+		int res = cred->cr_ops->cr_init(auth, cred);
+		if (res < 0) {
+			put_rpccred(cred);
+			cred = ERR_PTR(res);
+		}
+	}
+	rpcauth_destroy_credlist(&free);
+out:
+	return cred;
+}
+EXPORT_SYMBOL_GPL(rpcauth_lookup_credcache);
+
+struct rpc_cred *
+rpcauth_lookupcred(struct rpc_auth *auth, int flags)
+{
+	struct auth_cred acred;
+	struct rpc_cred *ret;
+	const struct cred *cred = current_cred();
+
+	memset(&acred, 0, sizeof(acred));
+	acred.cred = cred;
+	ret = auth->au_ops->lookup_cred(auth, &acred, flags);
+	return ret;
+}
+EXPORT_SYMBOL_GPL(rpcauth_lookupcred);
+
+void
+rpcauth_init_cred(struct rpc_cred *cred, const struct auth_cred *acred,
+		  struct rpc_auth *auth, const struct rpc_credops *ops)
+{
+	INIT_HLIST_NODE(&cred->cr_hash);
+	INIT_LIST_HEAD(&cred->cr_lru);
+	refcount_set(&cred->cr_count, 1);
+	cred->cr_auth = auth;
+	cred->cr_flags = 0;
+	cred->cr_ops = ops;
+	cred->cr_expire = jiffies;
+	cred->cr_cred = get_cred(acred->cred);
+}
+EXPORT_SYMBOL_GPL(rpcauth_init_cred);
+
+static struct rpc_cred *
+rpcauth_bind_root_cred(struct rpc_task *task, int lookupflags)
+{
+	struct rpc_auth *auth = task->tk_client->cl_auth;
+	struct auth_cred acred = {
+		.cred = get_task_cred(&init_task),
+	};
+	struct rpc_cred *ret;
+
+	if (RPC_IS_ASYNC(task))
+		lookupflags |= RPCAUTH_LOOKUP_ASYNC;
+	ret = auth->au_ops->lookup_cred(auth, &acred, lookupflags);
+	put_cred(acred.cred);
+	return ret;
+}
+
+static struct rpc_cred *
+rpcauth_bind_machine_cred(struct rpc_task *task, int lookupflags)
+{
+	struct rpc_auth *auth = task->tk_client->cl_auth;
+	struct auth_cred acred = {
+		.principal = task->tk_client->cl_principal,
+		.cred = init_task.cred,
+	};
+
+	if (!acred.principal)
+		return NULL;
+	if (RPC_IS_ASYNC(task))
+		lookupflags |= RPCAUTH_LOOKUP_ASYNC;
+	return auth->au_ops->lookup_cred(auth, &acred, lookupflags);
+}
+
+static struct rpc_cred *
+rpcauth_bind_new_cred(struct rpc_task *task, int lookupflags)
+{
+	struct rpc_auth *auth = task->tk_client->cl_auth;
+
+	return rpcauth_lookupcred(auth, lookupflags);
+}
+
+static int
+rpcauth_bindcred(struct rpc_task *task, const struct cred *cred, int flags)
+{
+	struct rpc_rqst *req = task->tk_rqstp;
+	struct rpc_cred *new = NULL;
+	int lookupflags = 0;
+	struct rpc_auth *auth = task->tk_client->cl_auth;
+	struct auth_cred acred = {
+		.cred = cred,
+	};
+
+	if (flags & RPC_TASK_ASYNC)
+		lookupflags |= RPCAUTH_LOOKUP_NEW | RPCAUTH_LOOKUP_ASYNC;
+	if (task->tk_op_cred)
+		/* Task must use exactly this rpc_cred */
+		new = get_rpccred(task->tk_op_cred);
+	else if (cred != NULL && cred != &machine_cred)
+		new = auth->au_ops->lookup_cred(auth, &acred, lookupflags);
+	else if (cred == &machine_cred)
+		new = rpcauth_bind_machine_cred(task, lookupflags);
+
+	/* If machine cred couldn't be bound, try a root cred */
+	if (new)
+		;
+	else if (cred == &machine_cred)
+		new = rpcauth_bind_root_cred(task, lookupflags);
+	else if (flags & RPC_TASK_NULLCREDS)
+		new = authnull_ops.lookup_cred(NULL, NULL, 0);
+	else
+		new = rpcauth_bind_new_cred(task, lookupflags);
+	if (IS_ERR(new))
+		return PTR_ERR(new);
+	put_rpccred(req->rq_cred);
+	req->rq_cred = new;
+	return 0;
+}
+
+void
+put_rpccred(struct rpc_cred *cred)
+{
+	if (cred == NULL)
+		return;
+	rcu_read_lock();
+	if (refcount_dec_and_test(&cred->cr_count))
+		goto destroy;
+	if (refcount_read(&cred->cr_count) != 1 ||
+	    !test_bit(RPCAUTH_CRED_HASHED, &cred->cr_flags))
+		goto out;
+	if (test_bit(RPCAUTH_CRED_UPTODATE, &cred->cr_flags) != 0) {
+		cred->cr_expire = jiffies;
+		rpcauth_lru_add(cred);
+		/* Race breaker */
+		if (unlikely(!test_bit(RPCAUTH_CRED_HASHED, &cred->cr_flags)))
+			rpcauth_lru_remove(cred);
+	} else if (rpcauth_unhash_cred(cred)) {
+		rpcauth_lru_remove(cred);
+		if (refcount_dec_and_test(&cred->cr_count))
+			goto destroy;
+	}
+out:
+	rcu_read_unlock();
+	return;
+destroy:
+	rcu_read_unlock();
+	cred->cr_ops->crdestroy(cred);
+}
+EXPORT_SYMBOL_GPL(put_rpccred);
+
+/**
+ * rpcauth_marshcred - Append RPC credential to end of @xdr
+ * @task: controlling RPC task
+ * @xdr: xdr_stream containing initial portion of RPC Call header
+ *
+ * On success, an appropriate verifier is added to @xdr, @xdr is
+ * updated to point past the verifier, and zero is returned.
+ * Otherwise, @xdr is in an undefined state and a negative errno
+ * is returned.
+ */
+int rpcauth_marshcred(struct rpc_task *task, struct xdr_stream *xdr)
+{
+	const struct rpc_credops *ops = task->tk_rqstp->rq_cred->cr_ops;
+
+	return ops->crmarshal(task, xdr);
+}
+
+/**
+ * rpcauth_wrap_req_encode - XDR encode the RPC procedure
+ * @task: controlling RPC task
+ * @xdr: stream where on-the-wire bytes are to be marshalled
+ *
+ * On success, @xdr contains the encoded and wrapped message.
+ * Otherwise, @xdr is in an undefined state.
+ */
+int rpcauth_wrap_req_encode(struct rpc_task *task, struct xdr_stream *xdr)
+{
+	kxdreproc_t encode = task->tk_msg.rpc_proc->p_encode;
+
+	encode(task->tk_rqstp, xdr, task->tk_msg.rpc_argp);
+	return 0;
+}
+EXPORT_SYMBOL_GPL(rpcauth_wrap_req_encode);
+
+/**
+ * rpcauth_wrap_req - XDR encode and wrap the RPC procedure
+ * @task: controlling RPC task
+ * @xdr: stream where on-the-wire bytes are to be marshalled
+ *
+ * On success, @xdr contains the encoded and wrapped message,
+ * and zero is returned. Otherwise, @xdr is in an undefined
+ * state and a negative errno is returned.
+ */
+int rpcauth_wrap_req(struct rpc_task *task, struct xdr_stream *xdr)
+{
+	const struct rpc_credops *ops = task->tk_rqstp->rq_cred->cr_ops;
+
+	return ops->crwrap_req(task, xdr);
+}
+
+/**
+ * rpcauth_checkverf - Validate verifier in RPC Reply header
+ * @task: controlling RPC task
+ * @xdr: xdr_stream containing RPC Reply header
+ *
+ * Return values:
+ *   %0: Verifier is valid. @xdr now points past the verifier.
+ *   %-EIO: Verifier is corrupted or message ended early.
+ *   %-EACCES: Verifier is intact but not valid.
+ *   %-EPROTONOSUPPORT: Server does not support the requested auth type.
+ *
+ * When a negative errno is returned, @xdr is left in an undefined
+ * state.
+ */
+int
+rpcauth_checkverf(struct rpc_task *task, struct xdr_stream *xdr)
+{
+	const struct rpc_credops *ops = task->tk_rqstp->rq_cred->cr_ops;
+
+	return ops->crvalidate(task, xdr);
+}
+
+/**
+ * rpcauth_unwrap_resp_decode - Invoke XDR decode function
+ * @task: controlling RPC task
+ * @xdr: stream where the Reply message resides
+ *
+ * Returns zero on success; otherwise a negative errno is returned.
+ */
+int
+rpcauth_unwrap_resp_decode(struct rpc_task *task, struct xdr_stream *xdr)
+{
+	kxdrdproc_t decode = task->tk_msg.rpc_proc->p_decode;
+
+	return decode(task->tk_rqstp, xdr, task->tk_msg.rpc_resp);
+}
+EXPORT_SYMBOL_GPL(rpcauth_unwrap_resp_decode);
+
+/**
+ * rpcauth_unwrap_resp - Invoke unwrap and decode function for the cred
+ * @task: controlling RPC task
+ * @xdr: stream where the Reply message resides
+ *
+ * Returns zero on success; otherwise a negative errno is returned.
+ */
+int
+rpcauth_unwrap_resp(struct rpc_task *task, struct xdr_stream *xdr)
+{
+	const struct rpc_credops *ops = task->tk_rqstp->rq_cred->cr_ops;
+
+	return ops->crunwrap_resp(task, xdr);
+}
+
+bool
+rpcauth_xmit_need_reencode(struct rpc_task *task)
+{
+	struct rpc_cred *cred = task->tk_rqstp->rq_cred;
+
+	if (!cred || !cred->cr_ops->crneed_reencode)
+		return false;
+	return cred->cr_ops->crneed_reencode(task);
+}
+
+int
+rpcauth_refreshcred(struct rpc_task *task)
+{
+	struct rpc_cred	*cred;
+	int err;
+
+	cred = task->tk_rqstp->rq_cred;
+	if (cred == NULL) {
+		err = rpcauth_bindcred(task, task->tk_msg.rpc_cred, task->tk_flags);
+		if (err < 0)
+			goto out;
+		cred = task->tk_rqstp->rq_cred;
+	}
+
+	err = cred->cr_ops->crrefresh(task);
+out:
+	if (err < 0)
+		task->tk_status = err;
+	return err;
+}
+
+void
+rpcauth_invalcred(struct rpc_task *task)
+{
+	struct rpc_cred *cred = task->tk_rqstp->rq_cred;
+
+	if (cred)
+		clear_bit(RPCAUTH_CRED_UPTODATE, &cred->cr_flags);
+}
+
+int
+rpcauth_uptodatecred(struct rpc_task *task)
+{
+	struct rpc_cred *cred = task->tk_rqstp->rq_cred;
+
+	return cred == NULL ||
+		test_bit(RPCAUTH_CRED_UPTODATE, &cred->cr_flags) != 0;
+}
+
+static struct shrinker rpc_cred_shrinker = {
+	.count_objects = rpcauth_cache_shrink_count,
+	.scan_objects = rpcauth_cache_shrink_scan,
+	.seeks = DEFAULT_SEEKS,
+};
+
+int __init rpcauth_init_module(void)
+{
+	int err;
+
+	err = rpc_init_authunix();
+	if (err < 0)
+		goto out1;
+	err = register_shrinker(&rpc_cred_shrinker, "sunrpc_cred");
+	if (err < 0)
+		goto out2;
+	return 0;
+out2:
+	rpc_destroy_authunix();
+out1:
+	return err;
+}
+
+void rpcauth_remove_module(void)
+{
+	rpc_destroy_authunix();
+	unregister_shrinker(&rpc_cred_shrinker);
+}