/*
   * Generic RPC credential
   *
   * Copyright (C) 2008, Trond Myklebust <Trond.Myklebust@netapp.com>
   */
  
  #include <linux/err.h>
  #include <linux/slab.h>
  #include <linux/types.h>
  #include <linux/module.h>
  #include <linux/sched.h>
  #include <linux/sunrpc/auth.h>
  #include <linux/sunrpc/clnt.h>
  #include <linux/sunrpc/debug.h>
  #include <linux/sunrpc/sched.h>
  
  #ifdef RPC_DEBUG
  # define RPCDBG_FACILITY	RPCDBG_AUTH
  #endif
  
  #define RPC_MACHINE_CRED_USERID		GLOBAL_ROOT_UID
  #define RPC_MACHINE_CRED_GROUPID	GLOBAL_ROOT_GID
  
  struct generic_cred {
  	struct rpc_cred gc_base;
  	struct auth_cred acred;
  };
  
  static struct rpc_auth generic_auth;
  static const struct rpc_credops generic_credops;
  
  /*
   * Public call interface
   */
  struct rpc_cred *rpc_lookup_cred(void)
  {
  	return rpcauth_lookupcred(&generic_auth, 0);
  }
  EXPORT_SYMBOL_GPL(rpc_lookup_cred);
  
  /*
   * Public call interface for looking up machine creds.
   */
  struct rpc_cred *rpc_lookup_machine_cred(const char *service_name)
  {
  	struct auth_cred acred = {
  		.uid = RPC_MACHINE_CRED_USERID,
  		.gid = RPC_MACHINE_CRED_GROUPID,
  		.principal = service_name,
  		.machine_cred = 1,
  	};
  
  	dprintk("RPC:       looking up machine cred for service %s
  ",
  			service_name);
  	return generic_auth.au_ops->lookup_cred(&generic_auth, &acred, 0);
  }
  EXPORT_SYMBOL_GPL(rpc_lookup_machine_cred);
  
  static struct rpc_cred *generic_bind_cred(struct rpc_task *task,
  		struct rpc_cred *cred, int lookupflags)
  {
  	struct rpc_auth *auth = task->tk_client->cl_auth;
  	struct auth_cred *acred = &container_of(cred, struct generic_cred, gc_base)->acred;
  
  	return auth->au_ops->lookup_cred(auth, acred, lookupflags);
  }
  
  /*
   * Lookup generic creds for current process
   */
  static struct rpc_cred *
  generic_lookup_cred(struct rpc_auth *auth, struct auth_cred *acred, int flags)
  {
  	return rpcauth_lookup_credcache(&generic_auth, acred, flags);
  }
  
  static struct rpc_cred *
  generic_create_cred(struct rpc_auth *auth, struct auth_cred *acred, int flags)
  {
  	struct generic_cred *gcred;
  
  	gcred = kmalloc(sizeof(*gcred), GFP_KERNEL);
  	if (gcred == NULL)
  		return ERR_PTR(-ENOMEM);
  
  	rpcauth_init_cred(&gcred->gc_base, acred, &generic_auth, &generic_credops);
  	gcred->gc_base.cr_flags = 1UL << RPCAUTH_CRED_UPTODATE;
  
  	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;
  	gcred->acred.principal = acred->principal;
  
  	dprintk("RPC:       allocated %s cred %p for uid %d gid %d
  ",
  			gcred->acred.machine_cred ? "machine" : "generic",
  			gcred,
  			from_kuid(&init_user_ns, acred->uid),
  			from_kgid(&init_user_ns, acred->gid));
  	return &gcred->gc_base;
  }
  
  static void
  generic_free_cred(struct rpc_cred *cred)
  {
  	struct generic_cred *gcred = container_of(cred, struct generic_cred, gc_base);
  
  	dprintk("RPC:       generic_free_cred %p
  ", gcred);
  	if (gcred->acred.group_info != NULL)
  		put_group_info(gcred->acred.group_info);
  	kfree(gcred);
  }
  
  static void
  generic_free_cred_callback(struct rcu_head *head)
  {
  	struct rpc_cred *cred = container_of(head, struct rpc_cred, cr_rcu);
  	generic_free_cred(cred);
  }
  
  static void
  generic_destroy_cred(struct rpc_cred *cred)
  {
  	call_rcu(&cred->cr_rcu, generic_free_cred_callback);
  }
  
  static int
  machine_cred_match(struct auth_cred *acred, struct generic_cred *gcred, int flags)
  {
  	if (!gcred->acred.machine_cred ||
  	    gcred->acred.principal != acred->principal ||
  	    !uid_eq(gcred->acred.uid, acred->uid) ||
  	    !gid_eq(gcred->acred.gid, acred->gid))
  		return 0;
  	return 1;
  }
  
  /*
   * Match credentials against current process creds.
   */
  static int
  generic_match(struct auth_cred *acred, struct rpc_cred *cred, int flags)
  {
  	struct generic_cred *gcred = container_of(cred, struct generic_cred, gc_base);
  	int i;
  
  	if (acred->machine_cred)
  		return machine_cred_match(acred, gcred, flags);
  
  	if (!uid_eq(gcred->acred.uid, acred->uid) ||
  	    !gid_eq(gcred->acred.gid, acred->gid) ||
  	    gcred->acred.machine_cred != 0)
  		goto out_nomatch;
  
  	/* Optimisation in the case where pointers are identical... */
  	if (gcred->acred.group_info == acred->group_info)
  		goto out_match;
  
  	/* Slow path... */
  	if (gcred->acred.group_info->ngroups != acred->group_info->ngroups)
  		goto out_nomatch;
  	for (i = 0; i < gcred->acred.group_info->ngroups; i++) {
  		if (!gid_eq(GROUP_AT(gcred->acred.group_info, i),
  				GROUP_AT(acred->group_info, i)))
  			goto out_nomatch;
  	}
  out_match:
  	return 1;
  out_nomatch:
  	return 0;
  }
  
  int __init rpc_init_generic_auth(void)
  {
  	return rpcauth_init_credcache(&generic_auth);
  }
  
  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
  ",
  				from_kuid(&init_user_ns, 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 = {
  	.au_ops = &generic_auth_ops,
  	.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,
  };