/*
   * 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/spinlock.h>
  
  #ifdef RPC_DEBUG
  # define RPCDBG_FACILITY	RPCDBG_AUTH
  #endif

  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;

  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);

  
  struct rpc_auth *
  rpcauth_create(rpc_authflavor_t pseudoflavor, struct rpc_clnt *clnt)
  {
  	struct rpc_auth		*auth;

  	const struct rpc_authops *ops;

  	u32			flavor = pseudoflavor_to_flavor(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(clnt, pseudoflavor);

  	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 void
  rpcauth_unhash_cred(struct rpc_cred *cred)
  {
  	spinlock_t *cache_lock;
  
  	cache_lock = &cred->cr_auth->au_credcache->lock;
  	spin_lock(cache_lock);
  	if (atomic_read(&cred->cr_count) == 0)
  		rpcauth_unhash_cred_locked(cred);
  	spin_unlock(cache_lock);
  }

  /*
   * Initialize RPC credential cache
   */
  int

  rpcauth_init_credcache(struct rpc_auth *auth)

  {
  	struct rpc_cred_cache *new;
  	int i;

  	new = kmalloc(sizeof(*new), GFP_KERNEL);

  	if (!new)
  		return -ENOMEM;
  	for (i = 0; i < RPC_CREDCACHE_NR; i++)
  		INIT_HLIST_HEAD(&new->hashtable[i]);

  	spin_lock_init(&new->lock);

  	auth->au_credcache = new;
  	return 0;
  }

  EXPORT_SYMBOL_GPL(rpcauth_init_credcache);

  
  /*
   * 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;
  	int		i;
  
  	spin_lock(&rpc_credcache_lock);

  	spin_lock(&cache->lock);

  	for (i = 0; i < RPC_CREDCACHE_NR; 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);
  	}
  }

  EXPORT_SYMBOL_GPL(rpcauth_destroy_credcache);

  
  #define RPC_AUTH_EXPIRY_MORATORIUM (60 * HZ)

  /*
   * Remove stale credentials. Avoid sleeping inside the loop.
   */

  static int
  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;

  	list_for_each_entry_safe(cred, next, &cred_unused, cr_lru) {
  
  		/* Enforce a 60 second garbage collection moratorium */

  		if (time_in_range_open(cred->cr_expire, expired, jiffies) &&

  		    test_bit(RPCAUTH_CRED_HASHED, &cred->cr_flags) != 0)
  			continue;

  		list_del_init(&cred->cr_lru);

  		number_cred_unused--;

  		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);

  			nr_to_scan--;

  		}
  		spin_unlock(cache_lock);

  		if (nr_to_scan == 0)
  			break;

  	}

  	return nr_to_scan;

  }
  
  /*

   * Run memory cache shrinker.

   */

  static int
  rpcauth_cache_shrinker(int nr_to_scan, gfp_t gfp_mask)

  {

  	LIST_HEAD(free);
  	int res;
  
  	if (list_empty(&cred_unused))
  		return 0;

  	spin_lock(&rpc_credcache_lock);

  	nr_to_scan = rpcauth_prune_expired(&free, nr_to_scan);
  	res = (number_cred_unused / 100) * sysctl_vfs_cache_pressure;

  	spin_unlock(&rpc_credcache_lock);

  	rpcauth_destroy_credlist(&free);
  	return res;

  }
  
  /*
   * 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 hlist_node *pos;

  	struct rpc_cred	*cred = NULL,
  			*entry, *new;

  	unsigned int nr;
  
  	nr = hash_long(acred->uid, RPC_CREDCACHE_HASHBITS);

  	rcu_read_lock();
  	hlist_for_each_entry_rcu(entry, pos, &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, pos, &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);

  void

  rpcauth_generic_bind_cred(struct rpc_task *task, struct rpc_cred *cred)
  {
  	task->tk_msg.rpc_cred = get_rpccred(cred);
  	dprintk("RPC: %5u holding %s cred %p
  ", task->tk_pid,
  			cred->cr_auth->au_ops->au_name, cred);
  }

  EXPORT_SYMBOL_GPL(rpcauth_generic_bind_cred);

  
  static void

  rpcauth_bind_root_cred(struct rpc_task *task)

  {

  	struct rpc_auth *auth = task->tk_client->cl_auth;

  	struct auth_cred acred = {

  		.uid = 0,
  		.gid = 0,

  	};
  	struct rpc_cred *ret;

  	dprintk("RPC: %5u looking up %s cred
  ",

  		task->tk_pid, task->tk_client->cl_auth->au_ops->au_name);

  	ret = auth->au_ops->lookup_cred(auth, &acred, 0);
  	if (!IS_ERR(ret))
  		task->tk_msg.rpc_cred = ret;
  	else
  		task->tk_status = PTR_ERR(ret);
  }

  static void
  rpcauth_bind_new_cred(struct rpc_task *task)

  {
  	struct rpc_auth *auth = task->tk_client->cl_auth;
  	struct rpc_cred *ret;
  
  	dprintk("RPC: %5u looking up %s cred
  ",
  		task->tk_pid, auth->au_ops->au_name);
  	ret = rpcauth_lookupcred(auth, 0);

  	if (!IS_ERR(ret))
  		task->tk_msg.rpc_cred = ret;
  	else
  		task->tk_status = PTR_ERR(ret);

  }
  
  void

  rpcauth_bindcred(struct rpc_task *task, struct rpc_cred *cred, int flags)

  {

  	if (cred != NULL)

  		cred->cr_ops->crbind(task, cred);

  	else if (flags & RPC_TASK_ROOTCREDS)
  		rpcauth_bind_root_cred(task);
  	else
  		rpcauth_bind_new_cred(task);

  }
  
  void
  put_rpccred(struct rpc_cred *cred)
  {

  	/* Fast path for unhashed credentials */

  	if (test_bit(RPCAUTH_CRED_HASHED, &cred->cr_flags) != 0)

  		goto need_lock;

  	if (!atomic_dec_and_test(&cred->cr_count))
  		return;

  	goto out_destroy;

  need_lock:
  	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_UPTODATE, &cred->cr_flags) == 0)

  		rpcauth_unhash_cred(cred);

  	if (test_bit(RPCAUTH_CRED_HASHED, &cred->cr_flags) != 0) {

  		cred->cr_expire = jiffies;
  		list_add_tail(&cred->cr_lru, &cred_unused);

  		number_cred_unused++;

  		spin_unlock(&rpc_credcache_lock);
  		return;
  	}
  	spin_unlock(&rpc_credcache_lock);
  out_destroy:

  	cred->cr_ops->crdestroy(cred);
  }

  EXPORT_SYMBOL_GPL(put_rpccred);

  
  void
  rpcauth_unbindcred(struct rpc_task *task)
  {

  	struct rpc_cred	*cred = task->tk_msg.rpc_cred;

  	dprintk("RPC: %5u releasing %s cred %p
  ",

  		task->tk_pid, cred->cr_auth->au_ops->au_name, cred);

  
  	put_rpccred(cred);
  	task->tk_msg.rpc_cred = NULL;
  }

  __be32 *
  rpcauth_marshcred(struct rpc_task *task, __be32 *p)

  {

  	struct rpc_cred	*cred = task->tk_msg.rpc_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_msg.rpc_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);
  }
  
  int
  rpcauth_wrap_req(struct rpc_task *task, kxdrproc_t encode, void *rqstp,

  		__be32 *data, void *obj)

  {
  	struct rpc_cred *cred = task->tk_msg.rpc_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. */

  	return encode(rqstp, data, obj);

  }
  
  int
  rpcauth_unwrap_resp(struct rpc_task *task, kxdrproc_t decode, void *rqstp,

  		__be32 *data, void *obj)

  {
  	struct rpc_cred *cred = task->tk_msg.rpc_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 decode(rqstp, data, obj);

  }
  
  int
  rpcauth_refreshcred(struct rpc_task *task)
  {

  	struct rpc_cred	*cred = task->tk_msg.rpc_cred;
  	int err;

  	dprintk("RPC: %5u refreshing %s cred %p
  ",

  		task->tk_pid, cred->cr_auth->au_ops->au_name, cred);

  	err = cred->cr_ops->crrefresh(task);
  	if (err < 0)
  		task->tk_status = err;
  	return err;
  }
  
  void
  rpcauth_invalcred(struct rpc_task *task)
  {

  	struct rpc_cred *cred = task->tk_msg.rpc_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_msg.rpc_cred;
  
  	return cred == NULL ||
  		test_bit(RPCAUTH_CRED_UPTODATE, &cred->cr_flags) != 0;

  }

  static struct shrinker rpc_cred_shrinker = {
  	.shrink = rpcauth_cache_shrinker,
  	.seeks = DEFAULT_SEEKS,
  };

  
  void __init rpcauth_init_module(void)
  {
  	rpc_init_authunix();

  	rpc_init_generic_auth();

  	register_shrinker(&rpc_cred_shrinker);

  }
  
  void __exit rpcauth_remove_module(void)
  {

  	unregister_shrinker(&rpc_cred_shrinker);

  }