/*
   * 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/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>
  
  #ifdef RPC_DEBUG
  # define RPCDBG_FACILITY	RPCDBG_AUTH
  #endif
  
  #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 DEFINE_SPINLOCK(rpc_authflavor_lock);
  static const struct rpc_authops *auth_flavors[RPC_AUTH_MAXFLAVOR] = {
  	&authnull_ops,		/* AUTH_NULL */
  	&authunix_ops,		/* AUTH_UNIX */
  	NULL,			/* others can be loadable modules */
  };
  
  static LIST_HEAD(cred_unused);
  static unsigned long number_cred_unused;
  
  #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 = strict_strtoul(val, 0, &num);
  	if (ret == -EINVAL)
  		goto out_inval;
  	nbits = fls(num);
  	if (num > (1U << nbits))
  		nbits++;
  	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", 1U << nbits);
  }
  
  #define param_check_hashtbl_sz(name, p) __param_check(name, p, unsigned int);
  
  static 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 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)
  {
  	rpc_authflavor_t flavor;
  	int ret = -EPERM;
  
  	if ((flavor = ops->au_flavor) >= RPC_AUTH_MAXFLAVOR)
  		return -EINVAL;
  	spin_lock(&rpc_authflavor_lock);
  	if (auth_flavors[flavor] == NULL) {
  		auth_flavors[flavor] = ops;
  		ret = 0;
  	}
  	spin_unlock(&rpc_authflavor_lock);
  	return ret;
  }
  EXPORT_SYMBOL_GPL(rpcauth_register);
  
  int
  rpcauth_unregister(const struct rpc_authops *ops)
  {
  	rpc_authflavor_t flavor;
  	int ret = -EPERM;
  
  	if ((flavor = ops->au_flavor) >= RPC_AUTH_MAXFLAVOR)
  		return -EINVAL;
  	spin_lock(&rpc_authflavor_lock);
  	if (auth_flavors[flavor] == ops) {
  		auth_flavors[flavor] = NULL;
  		ret = 0;
  	}
  	spin_unlock(&rpc_authflavor_lock);
  	return ret;
  }
  EXPORT_SYMBOL_GPL(rpcauth_unregister);
  
  /**
   * 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;
  	rpc_authflavor_t pseudoflavor;
  
  	ops = auth_flavors[flavor];
  	if (ops == NULL)
  		request_module("rpc-auth-%u", flavor);
  	spin_lock(&rpc_authflavor_lock);
  	ops = auth_flavors[flavor];
  	if (ops == NULL || !try_module_get(ops->owner)) {
  		spin_unlock(&rpc_authflavor_lock);
  		return RPC_AUTH_MAXFLAVOR;
  	}
  	spin_unlock(&rpc_authflavor_lock);
  
  	pseudoflavor = flavor;
  	if (ops->info2flavor != NULL)
  		pseudoflavor = ops->info2flavor(info);
  
  	module_put(ops->owner);
  	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;
  
  	if (flavor >= RPC_AUTH_MAXFLAVOR)
  		return -EINVAL;
  
  	ops = auth_flavors[flavor];
  	if (ops == NULL)
  		request_module("rpc-auth-%u", flavor);
  	spin_lock(&rpc_authflavor_lock);
  	ops = auth_flavors[flavor];
  	if (ops == NULL || !try_module_get(ops->owner)) {
  		spin_unlock(&rpc_authflavor_lock);
  		return -ENOENT;
  	}
  	spin_unlock(&rpc_authflavor_lock);
  
  	result = -ENOENT;
  	if (ops->flavor2info != NULL)
  		result = ops->flavor2info(pseudoflavor, info);
  
  	module_put(ops->owner);
  	return result;
  }
  EXPORT_SYMBOL_GPL(rpcauth_get_gssinfo);
  
  /**
   * rpcauth_list_flavors - discover registered flavors and pseudoflavors
   * @array: array to fill in
   * @size: size of "array"
   *
   * Returns the number of array items filled in, or a negative errno.
   *
   * The returned array is not sorted by any policy.  Callers should not
   * rely on the order of the items in the returned array.
   */
  int
  rpcauth_list_flavors(rpc_authflavor_t *array, int size)
  {
  	rpc_authflavor_t flavor;
  	int result = 0;
  
  	spin_lock(&rpc_authflavor_lock);
  	for (flavor = 0; flavor < RPC_AUTH_MAXFLAVOR; flavor++) {
  		const struct rpc_authops *ops = auth_flavors[flavor];
  		rpc_authflavor_t pseudos[4];
  		int i, len;
  
  		if (result >= size) {
  			result = -ENOMEM;
  			break;
  		}
  
  		if (ops == NULL)
  			continue;
  		if (ops->list_pseudoflavors == NULL) {
  			array[result++] = ops->au_flavor;
  			continue;
  		}
  		len = ops->list_pseudoflavors(pseudos, ARRAY_SIZE(pseudos));
  		if (len < 0) {
  			result = len;
  			break;
  		}
  		for (i = 0; i < len; i++) {
  			if (result >= size) {
  				result = -ENOMEM;
  				break;
  			}
  			array[result++] = pseudos[i];
  		}
  	}
  	spin_unlock(&rpc_authflavor_lock);
  
  	dprintk("RPC:       %s returns %d
  ", __func__, result);
  	return result;
  }
  EXPORT_SYMBOL_GPL(rpcauth_list_flavors);
  
  struct rpc_auth *
  rpcauth_create(struct rpc_auth_create_args *args, struct rpc_clnt *clnt)
  {
  	struct rpc_auth		*auth;
  	const struct rpc_authops *ops;
  	u32			flavor = pseudoflavor_to_flavor(args->pseudoflavor);
  
  	auth = ERR_PTR(-EINVAL);
  	if (flavor >= RPC_AUTH_MAXFLAVOR)
  		goto out;
  
  	if ((ops = auth_flavors[flavor]) == NULL)
  		request_module("rpc-auth-%u", flavor);
  	spin_lock(&rpc_authflavor_lock);
  	ops = auth_flavors[flavor];
  	if (ops == NULL || !try_module_get(ops->owner)) {
  		spin_unlock(&rpc_authflavor_lock);
  		goto out;
  	}
  	spin_unlock(&rpc_authflavor_lock);
  	auth = ops->create(args, clnt);
  	module_put(ops->owner);
  	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 (!atomic_dec_and_test(&auth->au_count))
  		return;
  	auth->au_ops->destroy(auth);
  }
  
  static DEFINE_SPINLOCK(rpc_credcache_lock);
  
  static void
  rpcauth_unhash_cred_locked(struct rpc_cred *cred)
  {
  	hlist_del_rcu(&cred->cr_hash);
  	smp_mb__before_clear_bit();
  	clear_bit(RPCAUTH_CRED_HASHED, &cred->cr_flags);
  }
  
  static int
  rpcauth_unhash_cred(struct rpc_cred *cred)
  {
  	spinlock_t *cache_lock;
  	int ret;
  
  	cache_lock = &cred->cr_auth->au_credcache->lock;
  	spin_lock(cache_lock);
  	ret = atomic_read(&cred->cr_count) == 0;
  	if (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);
  
  /*
   * Setup a credential key lifetime timeout notification
   */
  int
  rpcauth_key_timeout_notify(struct rpc_auth *auth, struct rpc_cred *cred)
  {
  	if (!cred->cr_auth->au_ops->key_timeout)
  		return 0;
  	return cred->cr_auth->au_ops->key_timeout(auth, cred);
  }
  EXPORT_SYMBOL_GPL(rpcauth_key_timeout_notify);
  
  bool
  rpcauth_cred_key_to_expire(struct rpc_cred *cred)
  {
  	if (!cred->cr_ops->crkey_to_expire)
  		return false;
  	return cred->cr_ops->crkey_to_expire(cred);
  }
  EXPORT_SYMBOL_GPL(rpcauth_cred_key_to_expire);
  
  /*
   * 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);
  	}
  }
  
  /*
   * 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);
  			get_rpccred(cred);
  			if (!list_empty(&cred->cr_lru)) {
  				list_del(&cred->cr_lru);
  				number_cred_unused--;
  			}
  			list_add_tail(&cred->cr_lru, &free);
  			rpcauth_unhash_cred_locked(cred);
  		}
  	}
  	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)
  {
  	spinlock_t *cache_lock;
  	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;
  		/*
  		 * 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) &&
  		    test_bit(RPCAUTH_CRED_HASHED, &cred->cr_flags) != 0)
  			break;
  
  		list_del_init(&cred->cr_lru);
  		number_cred_unused--;
  		freed++;
  		if (atomic_read(&cred->cr_count) != 0)
  			continue;
  
  		cache_lock = &cred->cr_auth->au_credcache->lock;
  		spin_lock(cache_lock);
  		if (atomic_read(&cred->cr_count) == 0) {
  			get_rpccred(cred);
  			list_add_tail(&cred->cr_lru, free);
  			rpcauth_unhash_cred_locked(cred);
  		}
  		spin_unlock(cache_lock);
  	}
  	return freed;
  }
  
  /*
   * Run memory cache shrinker.
   */
  static unsigned long
  rpcauth_cache_shrink_scan(struct shrinker *shrink, struct shrink_control *sc)
  
  {
  	LIST_HEAD(free);
  	unsigned long freed;
  
  	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;
  
  	spin_lock(&rpc_credcache_lock);
  	freed = rpcauth_prune_expired(&free, sc->nr_to_scan);
  	spin_unlock(&rpc_credcache_lock);
  	rpcauth_destroy_credlist(&free);
  
  	return freed;
  }
  
  static unsigned long
  rpcauth_cache_shrink_count(struct shrinker *shrink, struct shrink_control *sc)
  
  {
  	return (number_cred_unused / 100) * sysctl_vfs_cache_pressure;
  }
  
  /*
   * 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)
  {
  	LIST_HEAD(free);
  	struct rpc_cred_cache *cache = auth->au_credcache;
  	struct rpc_cred	*cred = NULL,
  			*entry, *new;
  	unsigned int nr;
  
  	nr = hash_long(from_kuid(&init_user_ns, acred->uid), 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;
  		spin_lock(&cache->lock);
  		if (test_bit(RPCAUTH_CRED_HASHED, &entry->cr_flags) == 0) {
  			spin_unlock(&cache->lock);
  			continue;
  		}
  		cred = get_rpccred(entry);
  		spin_unlock(&cache->lock);
  		break;
  	}
  	rcu_read_unlock();
  
  	if (cred != NULL)
  		goto found;
  
  	new = auth->au_ops->crcreate(auth, acred, flags);
  	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);
  		break;
  	}
  	if (cred == NULL) {
  		cred = new;
  		set_bit(RPCAUTH_CRED_HASHED, &cred->cr_flags);
  		hlist_add_head_rcu(&cred->cr_hash, &cache->hashtable[nr]);
  	} else
  		list_add_tail(&new->cr_lru, &free);
  	spin_unlock(&cache->lock);
  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();
  
  	dprintk("RPC:       looking up %s cred
  ",
  		auth->au_ops->au_name);
  
  	memset(&acred, 0, sizeof(acred));
  	acred.uid = cred->fsuid;
  	acred.gid = cred->fsgid;
  	acred.group_info = get_group_info(((struct cred *)cred)->group_info);
  
  	ret = auth->au_ops->lookup_cred(auth, &acred, flags);
  	put_group_info(acred.group_info);
  	return ret;
  }
  
  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);
  	atomic_set(&cred->cr_count, 1);
  	cred->cr_auth = auth;
  	cred->cr_ops = ops;
  	cred->cr_expire = jiffies;
  #ifdef RPC_DEBUG
  	cred->cr_magic = RPCAUTH_CRED_MAGIC;
  #endif
  	cred->cr_uid = acred->uid;
  }
  EXPORT_SYMBOL_GPL(rpcauth_init_cred);
  
  struct rpc_cred *
  rpcauth_generic_bind_cred(struct rpc_task *task, struct rpc_cred *cred, int lookupflags)
  {
  	dprintk("RPC: %5u holding %s cred %p
  ", task->tk_pid,
  			cred->cr_auth->au_ops->au_name, cred);
  	return get_rpccred(cred);
  }
  EXPORT_SYMBOL_GPL(rpcauth_generic_bind_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 = {
  		.uid = GLOBAL_ROOT_UID,
  		.gid = GLOBAL_ROOT_GID,
  	};
  
  	dprintk("RPC: %5u looking up %s cred
  ",
  		task->tk_pid, task->tk_client->cl_auth->au_ops->au_name);
  	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;
  
  	dprintk("RPC: %5u looking up %s cred
  ",
  		task->tk_pid, auth->au_ops->au_name);
  	return rpcauth_lookupcred(auth, lookupflags);
  }
  
  static int
  rpcauth_bindcred(struct rpc_task *task, struct rpc_cred *cred, int flags)
  {
  	struct rpc_rqst *req = task->tk_rqstp;
  	struct rpc_cred *new;
  	int lookupflags = 0;
  
  	if (flags & RPC_TASK_ASYNC)
  		lookupflags |= RPCAUTH_LOOKUP_NEW;
  	if (cred != NULL)
  		new = cred->cr_ops->crbind(task, cred, lookupflags);
  	else if (flags & RPC_TASK_ROOTCREDS)
  		new = rpcauth_bind_root_cred(task, lookupflags);
  	else
  		new = rpcauth_bind_new_cred(task, lookupflags);
  	if (IS_ERR(new))
  		return PTR_ERR(new);
  	if (req->rq_cred != NULL)
  		put_rpccred(req->rq_cred);
  	req->rq_cred = new;
  	return 0;
  }
  
  void
  put_rpccred(struct rpc_cred *cred)
  {
  	/* Fast path for unhashed credentials */
  	if (test_bit(RPCAUTH_CRED_HASHED, &cred->cr_flags) == 0) {
  		if (atomic_dec_and_test(&cred->cr_count))
  			cred->cr_ops->crdestroy(cred);
  		return;
  	}
  
  	if (!atomic_dec_and_lock(&cred->cr_count, &rpc_credcache_lock))
  		return;
  	if (!list_empty(&cred->cr_lru)) {
  		number_cred_unused--;
  		list_del_init(&cred->cr_lru);
  	}
  	if (test_bit(RPCAUTH_CRED_HASHED, &cred->cr_flags) != 0) {
  		if (test_bit(RPCAUTH_CRED_UPTODATE, &cred->cr_flags) != 0) {
  			cred->cr_expire = jiffies;
  			list_add_tail(&cred->cr_lru, &cred_unused);
  			number_cred_unused++;
  			goto out_nodestroy;
  		}
  		if (!rpcauth_unhash_cred(cred)) {
  			/* We were hashed and someone looked us up... */
  			goto out_nodestroy;
  		}
  	}
  	spin_unlock(&rpc_credcache_lock);
  	cred->cr_ops->crdestroy(cred);
  	return;
  out_nodestroy:
  	spin_unlock(&rpc_credcache_lock);
  }
  EXPORT_SYMBOL_GPL(put_rpccred);
  
  __be32 *
  rpcauth_marshcred(struct rpc_task *task, __be32 *p)
  {
  	struct rpc_cred	*cred = task->tk_rqstp->rq_cred;
  
  	dprintk("RPC: %5u marshaling %s cred %p
  ",
  		task->tk_pid, cred->cr_auth->au_ops->au_name, cred);
  
  	return cred->cr_ops->crmarshal(task, p);
  }
  
  __be32 *
  rpcauth_checkverf(struct rpc_task *task, __be32 *p)
  {
  	struct rpc_cred	*cred = task->tk_rqstp->rq_cred;
  
  	dprintk("RPC: %5u validating %s cred %p
  ",
  		task->tk_pid, cred->cr_auth->au_ops->au_name, cred);
  
  	return cred->cr_ops->crvalidate(task, p);
  }
  
  static void rpcauth_wrap_req_encode(kxdreproc_t encode, struct rpc_rqst *rqstp,
  				   __be32 *data, void *obj)
  {
  	struct xdr_stream xdr;
  
  	xdr_init_encode(&xdr, &rqstp->rq_snd_buf, data);
  	encode(rqstp, &xdr, obj);
  }
  
  int
  rpcauth_wrap_req(struct rpc_task *task, kxdreproc_t encode, void *rqstp,
  		__be32 *data, void *obj)
  {
  	struct rpc_cred *cred = task->tk_rqstp->rq_cred;
  
  	dprintk("RPC: %5u using %s cred %p to wrap rpc data
  ",
  			task->tk_pid, cred->cr_ops->cr_name, cred);
  	if (cred->cr_ops->crwrap_req)
  		return cred->cr_ops->crwrap_req(task, encode, rqstp, data, obj);
  	/* By default, we encode the arguments normally. */
  	rpcauth_wrap_req_encode(encode, rqstp, data, obj);
  	return 0;
  }
  
  static int
  rpcauth_unwrap_req_decode(kxdrdproc_t decode, struct rpc_rqst *rqstp,
  			  __be32 *data, void *obj)
  {
  	struct xdr_stream xdr;
  
  	xdr_init_decode(&xdr, &rqstp->rq_rcv_buf, data);
  	return decode(rqstp, &xdr, obj);
  }
  
  int
  rpcauth_unwrap_resp(struct rpc_task *task, kxdrdproc_t decode, void *rqstp,
  		__be32 *data, void *obj)
  {
  	struct rpc_cred *cred = task->tk_rqstp->rq_cred;
  
  	dprintk("RPC: %5u using %s cred %p to unwrap rpc data
  ",
  			task->tk_pid, cred->cr_ops->cr_name, cred);
  	if (cred->cr_ops->crunwrap_resp)
  		return cred->cr_ops->crunwrap_resp(task, decode, rqstp,
  						   data, obj);
  	/* By default, we decode the arguments normally. */
  	return rpcauth_unwrap_req_decode(decode, rqstp, data, obj);
  }
  
  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;
  	}
  	dprintk("RPC: %5u refreshing %s cred %p
  ",
  		task->tk_pid, cred->cr_auth->au_ops->au_name, 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;
  
  	dprintk("RPC: %5u invalidating %s cred %p
  ",
  		task->tk_pid, cred->cr_auth->au_ops->au_name, 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 = rpc_init_generic_auth();
  	if (err < 0)
  		goto out2;
  	register_shrinker(&rpc_cred_shrinker);
  	return 0;
  out2:
  	rpc_destroy_authunix();
  out1:
  	return err;
  }
  
  void rpcauth_remove_module(void)
  {
  	rpc_destroy_authunix();
  	rpc_destroy_generic_auth();
  	unregister_shrinker(&rpc_cred_shrinker);
  }