/*
   * fs/nfs/idmap.c
   *
   *  UID and GID to name mapping for clients.
   *
   *  Copyright (c) 2002 The Regents of the University of Michigan.
   *  All rights reserved.
   *
   *  Marius Aamodt Eriksen <marius@umich.edu>
   *
   *  Redistribution and use in source and binary forms, with or without
   *  modification, are permitted provided that the following conditions
   *  are met:
   *
   *  1. Redistributions of source code must retain the above copyright
   *     notice, this list of conditions and the following disclaimer.
   *  2. Redistributions in binary form must reproduce the above copyright
   *     notice, this list of conditions and the following disclaimer in the
   *     documentation and/or other materials provided with the distribution.
   *  3. Neither the name of the University nor the names of its
   *     contributors may be used to endorse or promote products derived
   *     from this software without specific prior written permission.
   *
   *  THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED
   *  WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
   *  MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
   *  DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
   *  FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
   *  CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
   *  SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
   *  BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
   *  LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
   *  NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
   *  SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
   */
  
  #include <linux/module.h>

  #include <linux/mutex.h>

  #include <linux/init.h>
  #include <linux/types.h>
  #include <linux/slab.h>
  #include <linux/socket.h>
  #include <linux/in.h>
  #include <linux/sched.h>
  
  #include <linux/sunrpc/clnt.h>
  #include <linux/workqueue.h>
  #include <linux/sunrpc/rpc_pipe_fs.h>

  #include <linux/nfs_fs.h>
  
  #include <linux/nfs_idmap.h>

  #include "nfs4_fs.h"

  
  #define IDMAP_HASH_SZ          128

  /* Default cache timeout is 10 minutes */
  unsigned int nfs_idmap_cache_timeout = 600 * HZ;

  static int param_set_idmap_timeout(const char *val, struct kernel_param *kp)
  {
  	char *endp;
  	int num = simple_strtol(val, &endp, 0);
  	int jif = num * HZ;
  	if (endp == val || *endp || num < 0 || jif < num)
  		return -EINVAL;
  	*((int *)kp->arg) = jif;
  	return 0;
  }
  
  module_param_call(idmap_cache_timeout, param_set_idmap_timeout, param_get_int,
  		 &nfs_idmap_cache_timeout, 0644);

  struct idmap_hashent {

  	unsigned long ih_expires;

  	__u32 ih_id;
  	int ih_namelen;
  	char ih_name[IDMAP_NAMESZ];
  };
  
  struct idmap_hashtable {
  	__u8 h_type;
  	struct idmap_hashent h_entries[IDMAP_HASH_SZ];
  };
  
  struct idmap {

  	struct dentry        *idmap_dentry;
  	wait_queue_head_t     idmap_wq;
  	struct idmap_msg      idmap_im;

  	struct mutex          idmap_lock;    /* Serializes upcalls */
  	struct mutex          idmap_im_lock; /* Protects the hashtable */

  	struct idmap_hashtable idmap_user_hash;
  	struct idmap_hashtable idmap_group_hash;
  };
  
  static ssize_t   idmap_pipe_upcall(struct file *, struct rpc_pipe_msg *,
  		     char __user *, size_t);
  static ssize_t   idmap_pipe_downcall(struct file *, const char __user *,
  		     size_t);

  static void      idmap_pipe_destroy_msg(struct rpc_pipe_msg *);

  
  static unsigned int fnvhash32(const void *, size_t);
  
  static struct rpc_pipe_ops idmap_upcall_ops = {
          .upcall         = idmap_pipe_upcall,
          .downcall       = idmap_pipe_downcall,
          .destroy_msg    = idmap_pipe_destroy_msg,
  };

  int

  nfs_idmap_new(struct nfs_client *clp)

  {
  	struct idmap *idmap;

  	int error;

  	BUG_ON(clp->cl_idmap != NULL);

          if ((idmap = kzalloc(sizeof(*idmap), GFP_KERNEL)) == NULL)

                  return -ENOMEM;

          idmap->idmap_dentry = rpc_mkpipe(clp->cl_rpcclient->cl_dentry, "idmap",

  	    idmap, &idmap_upcall_ops, 0);
          if (IS_ERR(idmap->idmap_dentry)) {

  		error = PTR_ERR(idmap->idmap_dentry);

  		kfree(idmap);

  		return error;

  	}

          mutex_init(&idmap->idmap_lock);
          mutex_init(&idmap->idmap_im_lock);

  	init_waitqueue_head(&idmap->idmap_wq);
  	idmap->idmap_user_hash.h_type = IDMAP_TYPE_USER;
  	idmap->idmap_group_hash.h_type = IDMAP_TYPE_GROUP;
  
  	clp->cl_idmap = idmap;

  	return 0;

  }
  
  void

  nfs_idmap_delete(struct nfs_client *clp)

  {
  	struct idmap *idmap = clp->cl_idmap;
  
  	if (!idmap)
  		return;

  	rpc_unlink(idmap->idmap_dentry);

  	clp->cl_idmap = NULL;
  	kfree(idmap);
  }
  
  /*
   * Helper routines for manipulating the hashtable
   */
  static inline struct idmap_hashent *
  idmap_name_hash(struct idmap_hashtable* h, const char *name, size_t len)
  {
  	return &h->h_entries[fnvhash32(name, len) % IDMAP_HASH_SZ];
  }
  
  static struct idmap_hashent *
  idmap_lookup_name(struct idmap_hashtable *h, const char *name, size_t len)
  {
  	struct idmap_hashent *he = idmap_name_hash(h, name, len);
  
  	if (he->ih_namelen != len || memcmp(he->ih_name, name, len) != 0)
  		return NULL;

  	if (time_after(jiffies, he->ih_expires))
  		return NULL;

  	return he;
  }
  
  static inline struct idmap_hashent *
  idmap_id_hash(struct idmap_hashtable* h, __u32 id)
  {
  	return &h->h_entries[fnvhash32(&id, sizeof(id)) % IDMAP_HASH_SZ];
  }
  
  static struct idmap_hashent *
  idmap_lookup_id(struct idmap_hashtable *h, __u32 id)
  {
  	struct idmap_hashent *he = idmap_id_hash(h, id);
  	if (he->ih_id != id || he->ih_namelen == 0)
  		return NULL;

  	if (time_after(jiffies, he->ih_expires))
  		return NULL;

  	return he;
  }
  
  /*
   * Routines for allocating new entries in the hashtable.
   * For now, we just have 1 entry per bucket, so it's all
   * pretty trivial.
   */
  static inline struct idmap_hashent *
  idmap_alloc_name(struct idmap_hashtable *h, char *name, unsigned len)
  {
  	return idmap_name_hash(h, name, len);
  }
  
  static inline struct idmap_hashent *
  idmap_alloc_id(struct idmap_hashtable *h, __u32 id)
  {
  	return idmap_id_hash(h, id);
  }
  
  static void
  idmap_update_entry(struct idmap_hashent *he, const char *name,
  		size_t namelen, __u32 id)
  {
  	he->ih_id = id;
  	memcpy(he->ih_name, name, namelen);
  	he->ih_name[namelen] = '\0';
  	he->ih_namelen = namelen;

  	he->ih_expires = jiffies + nfs_idmap_cache_timeout;

  }
  
  /*
   * Name -> ID
   */
  static int
  nfs_idmap_id(struct idmap *idmap, struct idmap_hashtable *h,
  		const char *name, size_t namelen, __u32 *id)
  {
  	struct rpc_pipe_msg msg;
  	struct idmap_msg *im;
  	struct idmap_hashent *he;
  	DECLARE_WAITQUEUE(wq, current);
  	int ret = -EIO;
  
  	im = &idmap->idmap_im;
  
  	/*
  	 * String sanity checks
  	 * Note that the userland daemon expects NUL terminated strings
  	 */
  	for (;;) {
  		if (namelen == 0)
  			return -EINVAL;
  		if (name[namelen-1] != '\0')
  			break;
  		namelen--;
  	}
  	if (namelen >= IDMAP_NAMESZ)
  		return -EINVAL;

  	mutex_lock(&idmap->idmap_lock);
  	mutex_lock(&idmap->idmap_im_lock);

  
  	he = idmap_lookup_name(h, name, namelen);
  	if (he != NULL) {
  		*id = he->ih_id;
  		ret = 0;
  		goto out;
  	}
  
  	memset(im, 0, sizeof(*im));
  	memcpy(im->im_name, name, namelen);
  
  	im->im_type = h->h_type;
  	im->im_conv = IDMAP_CONV_NAMETOID;
  
  	memset(&msg, 0, sizeof(msg));
  	msg.data = im;
  	msg.len = sizeof(*im);
  
  	add_wait_queue(&idmap->idmap_wq, &wq);
  	if (rpc_queue_upcall(idmap->idmap_dentry->d_inode, &msg) < 0) {
  		remove_wait_queue(&idmap->idmap_wq, &wq);
  		goto out;
  	}
  
  	set_current_state(TASK_UNINTERRUPTIBLE);

  	mutex_unlock(&idmap->idmap_im_lock);

  	schedule();

  	__set_current_state(TASK_RUNNING);

  	remove_wait_queue(&idmap->idmap_wq, &wq);

  	mutex_lock(&idmap->idmap_im_lock);

  
  	if (im->im_status & IDMAP_STATUS_SUCCESS) {
  		*id = im->im_id;
  		ret = 0;
  	}
  
   out:
  	memset(im, 0, sizeof(*im));

  	mutex_unlock(&idmap->idmap_im_lock);
  	mutex_unlock(&idmap->idmap_lock);

  	return (ret);
  }
  
  /*
   * ID -> Name
   */
  static int
  nfs_idmap_name(struct idmap *idmap, struct idmap_hashtable *h,
  		__u32 id, char *name)
  {
  	struct rpc_pipe_msg msg;
  	struct idmap_msg *im;
  	struct idmap_hashent *he;
  	DECLARE_WAITQUEUE(wq, current);
  	int ret = -EIO;
  	unsigned int len;
  
  	im = &idmap->idmap_im;

  	mutex_lock(&idmap->idmap_lock);
  	mutex_lock(&idmap->idmap_im_lock);

  
  	he = idmap_lookup_id(h, id);
  	if (he != 0) {
  		memcpy(name, he->ih_name, he->ih_namelen);
  		ret = he->ih_namelen;
  		goto out;
  	}
  
  	memset(im, 0, sizeof(*im));
  	im->im_type = h->h_type;
  	im->im_conv = IDMAP_CONV_IDTONAME;
  	im->im_id = id;
  
  	memset(&msg, 0, sizeof(msg));
  	msg.data = im;
  	msg.len = sizeof(*im);
  
  	add_wait_queue(&idmap->idmap_wq, &wq);
  
  	if (rpc_queue_upcall(idmap->idmap_dentry->d_inode, &msg) < 0) {
  		remove_wait_queue(&idmap->idmap_wq, &wq);
  		goto out;
  	}
  
  	set_current_state(TASK_UNINTERRUPTIBLE);

  	mutex_unlock(&idmap->idmap_im_lock);

  	schedule();

  	__set_current_state(TASK_RUNNING);

  	remove_wait_queue(&idmap->idmap_wq, &wq);

  	mutex_lock(&idmap->idmap_im_lock);

  
  	if (im->im_status & IDMAP_STATUS_SUCCESS) {
  		if ((len = strnlen(im->im_name, IDMAP_NAMESZ)) == 0)
  			goto out;
  		memcpy(name, im->im_name, len);
  		ret = len;
  	}
  
   out:
  	memset(im, 0, sizeof(*im));

  	mutex_unlock(&idmap->idmap_im_lock);
  	mutex_unlock(&idmap->idmap_lock);

  	return ret;
  }
  
  /* RPC pipefs upcall/downcall routines */
  static ssize_t
  idmap_pipe_upcall(struct file *filp, struct rpc_pipe_msg *msg,
      char __user *dst, size_t buflen)
  {
          char *data = (char *)msg->data + msg->copied;
          ssize_t mlen = msg->len - msg->copied;
          ssize_t left;
  
          if (mlen > buflen)
                  mlen = buflen;
  
          left = copy_to_user(dst, data, mlen);
  	if (left < 0) {
  		msg->errno = left;
  		return left;
  	}
  	mlen -= left;
  	msg->copied += mlen;
  	msg->errno = 0;
          return mlen;
  }
  
  static ssize_t
  idmap_pipe_downcall(struct file *filp, const char __user *src, size_t mlen)
  {

          struct rpc_inode *rpci = RPC_I(filp->f_path.dentry->d_inode);

  	struct idmap *idmap = (struct idmap *)rpci->private;
  	struct idmap_msg im_in, *im = &idmap->idmap_im;
  	struct idmap_hashtable *h;
  	struct idmap_hashent *he = NULL;
  	int namelen_in;
  	int ret;
  
          if (mlen != sizeof(im_in))
                  return (-ENOSPC);
  
          if (copy_from_user(&im_in, src, mlen) != 0)
  		return (-EFAULT);

  	mutex_lock(&idmap->idmap_im_lock);

  
  	ret = mlen;
  	im->im_status = im_in.im_status;
  	/* If we got an error, terminate now, and wake up pending upcalls */
  	if (!(im_in.im_status & IDMAP_STATUS_SUCCESS)) {
  		wake_up(&idmap->idmap_wq);
  		goto out;
  	}
  
  	/* Sanity checking of strings */
  	ret = -EINVAL;
  	namelen_in = strnlen(im_in.im_name, IDMAP_NAMESZ);
  	if (namelen_in == 0 || namelen_in == IDMAP_NAMESZ)
  		goto out;
  
  	switch (im_in.im_type) {
  		case IDMAP_TYPE_USER:
  			h = &idmap->idmap_user_hash;
  			break;
  		case IDMAP_TYPE_GROUP:
  			h = &idmap->idmap_group_hash;
  			break;
  		default:
  			goto out;
  	}
  
  	switch (im_in.im_conv) {
  	case IDMAP_CONV_IDTONAME:
  		/* Did we match the current upcall? */
  		if (im->im_conv == IDMAP_CONV_IDTONAME
  				&& im->im_type == im_in.im_type
  				&& im->im_id == im_in.im_id) {
  			/* Yes: copy string, including the terminating '\0'  */
  			memcpy(im->im_name, im_in.im_name, namelen_in);
  			im->im_name[namelen_in] = '\0';
  			wake_up(&idmap->idmap_wq);
  		}
  		he = idmap_alloc_id(h, im_in.im_id);
  		break;
  	case IDMAP_CONV_NAMETOID:
  		/* Did we match the current upcall? */
  		if (im->im_conv == IDMAP_CONV_NAMETOID
  				&& im->im_type == im_in.im_type
  				&& strnlen(im->im_name, IDMAP_NAMESZ) == namelen_in
  				&& memcmp(im->im_name, im_in.im_name, namelen_in) == 0) {
  			im->im_id = im_in.im_id;
  			wake_up(&idmap->idmap_wq);
  		}
  		he = idmap_alloc_name(h, im_in.im_name, namelen_in);
  		break;
  	default:
  		goto out;
  	}
  
  	/* If the entry is valid, also copy it to the cache */
  	if (he != NULL)
  		idmap_update_entry(he, im_in.im_name, namelen_in, im_in.im_id);
  	ret = mlen;
  out:

  	mutex_unlock(&idmap->idmap_im_lock);

  	return ret;
  }

  static void

  idmap_pipe_destroy_msg(struct rpc_pipe_msg *msg)
  {
  	struct idmap_msg *im = msg->data;
  	struct idmap *idmap = container_of(im, struct idmap, idmap_im); 
  
  	if (msg->errno >= 0)
  		return;

  	mutex_lock(&idmap->idmap_im_lock);

  	im->im_status = IDMAP_STATUS_LOOKUPFAIL;
  	wake_up(&idmap->idmap_wq);

  	mutex_unlock(&idmap->idmap_im_lock);

  }
  
  /* 
   * Fowler/Noll/Vo hash
   *    http://www.isthe.com/chongo/tech/comp/fnv/
   */
  
  #define FNV_P_32 ((unsigned int)0x01000193) /* 16777619 */
  #define FNV_1_32 ((unsigned int)0x811c9dc5) /* 2166136261 */
  
  static unsigned int fnvhash32(const void *buf, size_t buflen)
  {
  	const unsigned char *p, *end = (const unsigned char *)buf + buflen;
  	unsigned int hash = FNV_1_32;
  
  	for (p = buf; p < end; p++) {
  		hash *= FNV_P_32;
  		hash ^= (unsigned int)*p;
  	}
  
  	return (hash);
  }

  int nfs_map_name_to_uid(struct nfs_client *clp, const char *name, size_t namelen, __u32 *uid)

  {
  	struct idmap *idmap = clp->cl_idmap;
  
  	return nfs_idmap_id(idmap, &idmap->idmap_user_hash, name, namelen, uid);
  }

  int nfs_map_group_to_gid(struct nfs_client *clp, const char *name, size_t namelen, __u32 *uid)

  {
  	struct idmap *idmap = clp->cl_idmap;
  
  	return nfs_idmap_id(idmap, &idmap->idmap_group_hash, name, namelen, uid);
  }

  int nfs_map_uid_to_name(struct nfs_client *clp, __u32 uid, char *buf)

  {
  	struct idmap *idmap = clp->cl_idmap;
  
  	return nfs_idmap_name(idmap, &idmap->idmap_user_hash, uid, buf);
  }

  int nfs_map_gid_to_group(struct nfs_client *clp, __u32 uid, char *buf)

  {
  	struct idmap *idmap = clp->cl_idmap;
  
  	return nfs_idmap_name(idmap, &idmap->idmap_group_hash, uid, buf);
  }