/*
 * 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;
        size_t                  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 const 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);

        idmap = kzalloc(sizeof(*idmap), GFP_KERNEL);
        if (idmap == NULL)
                return -ENOMEM;

        idmap->idmap_dentry = rpc_mkpipe(clp->cl_rpcclient->cl_path.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, size_t 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) {
                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;
        size_t mlen = min(msg->len, buflen);
        unsigned long left;

        left = copy_to_user(dst, data, mlen);
        if (left == mlen) {
                msg->errno = -EFAULT;
                return -EFAULT;
        }

        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;
        size_t 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);
}