/*

  *  Copyright (c) 2004 The Regents of the University of Michigan.
  *  All rights reserved.
  *
  *  Andy Adamson <andros@citi.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/file.h>

  #include <linux/slab.h>

  #include <linux/namei.h>

  #include <linux/crypto.h>

  #include <linux/sched.h>

  
  #include "nfsd.h"
  #include "state.h"

  #include "vfs.h"

  
  #define NFSDDBG_FACILITY                NFSDDBG_PROC

  /* Globals */

  static struct file *rec_file;

  static char user_recovery_dirname[PATH_MAX] = "/var/lib/nfs/v4recovery";

  static int
  nfs4_save_creds(const struct cred **original_creds)

  {

  	struct cred *new;
  
  	new = prepare_creds();
  	if (!new)
  		return -ENOMEM;
  
  	new->fsuid = 0;
  	new->fsgid = 0;
  	*original_creds = override_creds(new);
  	put_cred(new);
  	return 0;

  }
  
  static void

  nfs4_reset_creds(const struct cred *original)

  {

  	revert_creds(original);

  }

  static void
  md5_to_hex(char *out, char *md5)
  {
  	int i;
  
  	for (i=0; i<16; i++) {
  		unsigned char c = md5[i];
  
  		*out++ = '0' + ((c&0xf0)>>4) + (c>=0xa0)*('a'-'9'-1);
  		*out++ = '0' + (c&0x0f) + ((c&0x0f)>=0x0a)*('a'-'9'-1);
  	}
  	*out = '\0';
  }

  __be32

  nfs4_make_rec_clidname(char *dname, struct xdr_netobj *clname)
  {
  	struct xdr_netobj cksum;

  	struct hash_desc desc;

  	struct scatterlist sg;

  	__be32 status = nfserr_jukebox;

  
  	dprintk("NFSD: nfs4_make_rec_clidname for %.*s
  ",
  			clname->len, clname->data);

  	desc.flags = CRYPTO_TFM_REQ_MAY_SLEEP;
  	desc.tfm = crypto_alloc_hash("md5", 0, CRYPTO_ALG_ASYNC);
  	if (IS_ERR(desc.tfm))
  		goto out_no_tfm;
  	cksum.len = crypto_hash_digestsize(desc.tfm);

  	cksum.data = kmalloc(cksum.len, GFP_KERNEL);
  	if (cksum.data == NULL)
   		goto out;

  	sg_init_one(&sg, clname->data, clname->len);

  	if (crypto_hash_digest(&desc, &sg, sg.length, cksum.data))

  		goto out;

  
  	md5_to_hex(dname, cksum.data);

  	status = nfs_ok;
  out:

  	kfree(cksum.data);

  	crypto_free_hash(desc.tfm);
  out_no_tfm:

  	return status;
  }

  int
  nfsd4_create_clid_dir(struct nfs4_client *clp)
  {

  	const struct cred *original_cred;

  	char *dname = clp->cl_recdir;

  	struct dentry *dir, *dentry;

  	int status;
  
  	dprintk("NFSD: nfsd4_create_clid_dir for \"%s\"
  ", dname);

  	if (!rec_file || clp->cl_firststate)

  		return 0;

  	clp->cl_firststate = 1;

  	status = nfs4_save_creds(&original_cred);
  	if (status < 0)
  		return status;

  	dir = rec_file->f_path.dentry;

  	/* lock the parent */

  	mutex_lock(&dir->d_inode->i_mutex);

  	dentry = lookup_one_len(dname, dir, HEXDIR_LEN-1);

  	if (IS_ERR(dentry)) {
  		status = PTR_ERR(dentry);
  		goto out_unlock;
  	}
  	status = -EEXIST;

  	if (dentry->d_inode)

  		goto out_put;

  	status = mnt_want_write(rec_file->f_path.mnt);

  	if (status)
  		goto out_put;

  	status = vfs_mkdir(dir->d_inode, dentry, S_IRWXU);
  	mnt_drop_write(rec_file->f_path.mnt);

  out_put:
  	dput(dentry);
  out_unlock:

  	mutex_unlock(&dir->d_inode->i_mutex);

  	if (status == 0)

  		vfs_fsync(rec_file, 0);

  	else
  		printk(KERN_ERR "NFSD: failed to write recovery record"
  				" (err %d); please check that %s exists"
  				" and is writeable", status,
  				user_recovery_dirname);

  	nfs4_reset_creds(original_cred);

  	return status;
  }

  typedef int (recdir_func)(struct dentry *, struct dentry *);

  struct name_list {
  	char name[HEXDIR_LEN];

  	struct list_head list;
  };

  static int

  nfsd4_build_namelist(void *arg, const char *name, int namlen,

  		loff_t offset, u64 ino, unsigned int d_type)

  {

  	struct list_head *names = arg;
  	struct name_list *entry;

  	if (namlen != HEXDIR_LEN - 1)

  		return 0;

  	entry = kmalloc(sizeof(struct name_list), GFP_KERNEL);
  	if (entry == NULL)

  		return -ENOMEM;

  	memcpy(entry->name, name, HEXDIR_LEN - 1);
  	entry->name[HEXDIR_LEN - 1] = '\0';
  	list_add(&entry->list, names);

  	return 0;
  }
  
  static int

  nfsd4_list_rec_dir(recdir_func *f)

  {

  	const struct cred *original_cred;

  	struct dentry *dir = rec_file->f_path.dentry;

  	LIST_HEAD(names);

  	int status;

  	status = nfs4_save_creds(&original_cred);
  	if (status < 0)
  		return status;

  	status = vfs_llseek(rec_file, 0, SEEK_SET);
  	if (status < 0) {
  		nfs4_reset_creds(original_cred);
  		return status;
  	}
  
  	status = vfs_readdir(rec_file, nfsd4_build_namelist, &names);

  	mutex_lock_nested(&dir->d_inode->i_mutex, I_MUTEX_PARENT);

  	while (!list_empty(&names)) {

  		struct name_list *entry;

  		entry = list_entry(names.next, struct name_list, list);

  		if (!status) {
  			struct dentry *dentry;
  			dentry = lookup_one_len(entry->name, dir, HEXDIR_LEN-1);
  			if (IS_ERR(dentry)) {
  				status = PTR_ERR(dentry);
  				break;
  			}
  			status = f(dir, dentry);
  			dput(dentry);

  		}

  		list_del(&entry->list);
  		kfree(entry);

  	}

  	mutex_unlock(&dir->d_inode->i_mutex);

  	nfs4_reset_creds(original_cred);

  	return status;
  }
  
  static int

  nfsd4_unlink_clid_dir(char *name, int namlen)
  {

  	struct dentry *dir, *dentry;

  	int status;
  
  	dprintk("NFSD: nfsd4_unlink_clid_dir. name %.*s
  ", namlen, name);

  	dir = rec_file->f_path.dentry;
  	mutex_lock_nested(&dir->d_inode->i_mutex, I_MUTEX_PARENT);
  	dentry = lookup_one_len(name, dir, namlen);

  	if (IS_ERR(dentry)) {
  		status = PTR_ERR(dentry);

  		goto out_unlock;

  	}
  	status = -ENOENT;
  	if (!dentry->d_inode)
  		goto out;

  	status = vfs_rmdir(dir->d_inode, dentry);

  out:
  	dput(dentry);

  out_unlock:

  	mutex_unlock(&dir->d_inode->i_mutex);

  	return status;
  }
  
  void
  nfsd4_remove_clid_dir(struct nfs4_client *clp)
  {

  	const struct cred *original_cred;

  	int status;

  	if (!rec_file || !clp->cl_firststate)

  		return;

  	status = mnt_want_write(rec_file->f_path.mnt);

  	if (status)
  		goto out;

  	clp->cl_firststate = 0;

  
  	status = nfs4_save_creds(&original_cred);
  	if (status < 0)
  		goto out;

  	status = nfsd4_unlink_clid_dir(clp->cl_recdir, HEXDIR_LEN-1);

  	nfs4_reset_creds(original_cred);

  	if (status == 0)

  		vfs_fsync(rec_file, 0);

  	mnt_drop_write(rec_file->f_path.mnt);

  out:

  	if (status)
  		printk("NFSD: Failed to remove expired client state directory"
  				" %.*s
  ", HEXDIR_LEN, clp->cl_recdir);
  	return;
  }
  
  static int
  purge_old(struct dentry *parent, struct dentry *child)
  {
  	int status;

  	if (nfs4_has_reclaimed_state(child->d_name.name, false))

  		return 0;

  	status = vfs_rmdir(parent->d_inode, child);

  	if (status)
  		printk("failed to remove client recovery directory %s
  ",
  				child->d_name.name);
  	/* Keep trying, success or failure: */

  	return 0;

  }
  
  void
  nfsd4_recdir_purge_old(void) {
  	int status;

  	if (!rec_file)

  		return;

  	status = mnt_want_write(rec_file->f_path.mnt);

  	if (status)
  		goto out;

  	status = nfsd4_list_rec_dir(purge_old);

  	if (status == 0)

  		vfs_fsync(rec_file, 0);

  	mnt_drop_write(rec_file->f_path.mnt);

  out:

  	if (status)
  		printk("nfsd4: failed to purge old clients from recovery"

  			" directory %s
  ", rec_file->f_path.dentry->d_name.name);

  }
  
  static int

  load_recdir(struct dentry *parent, struct dentry *child)
  {
  	if (child->d_name.len != HEXDIR_LEN - 1) {
  		printk("nfsd4: illegal name %s in recovery directory
  ",
  				child->d_name.name);
  		/* Keep trying; maybe the others are OK: */

  		return 0;

  	}
  	nfs4_client_to_reclaim(child->d_name.name);

  	return 0;

  }
  
  int
  nfsd4_recdir_load(void) {
  	int status;

  	if (!rec_file)
  		return 0;

  	status = nfsd4_list_rec_dir(load_recdir);

  	if (status)
  		printk("nfsd4: failed loading clients from recovery"

  			" directory %s
  ", rec_file->f_path.dentry->d_name.name);

  	return status;
  }
  
  /*
   * Hold reference to the recovery directory.
   */
  
  void

  nfsd4_init_recdir()

  {

  	const struct cred *original_cred;
  	int status;

  
  	printk("NFSD: Using %s as the NFSv4 state recovery directory
  ",

  			user_recovery_dirname);

  	BUG_ON(rec_file);

  	status = nfs4_save_creds(&original_cred);
  	if (status < 0) {
  		printk("NFSD: Unable to change credentials to find recovery"
  		       " directory: error %d
  ",
  		       status);
  		return;
  	}

  	rec_file = filp_open(user_recovery_dirname, O_RDONLY | O_DIRECTORY, 0);

  	if (IS_ERR(rec_file)) {

  		printk("NFSD: unable to find recovery directory %s
  ",

  				user_recovery_dirname);

  		rec_file = NULL;
  	}

  	nfs4_reset_creds(original_cred);

  }
  
  void
  nfsd4_shutdown_recdir(void)
  {

  	if (!rec_file)

  		return;

  	fput(rec_file);
  	rec_file = NULL;

  }

  
  /*
   * Change the NFSv4 recovery directory to recdir.
   */
  int
  nfs4_reset_recoverydir(char *recdir)
  {
  	int status;
  	struct path path;
  
  	status = kern_path(recdir, LOOKUP_FOLLOW, &path);
  	if (status)
  		return status;
  	status = -ENOTDIR;
  	if (S_ISDIR(path.dentry->d_inode->i_mode)) {
  		strcpy(user_recovery_dirname, recdir);
  		status = 0;
  	}
  	path_put(&path);
  	return status;
  }
  
  char *
  nfs4_recoverydir(void)
  {
  	return user_recovery_dirname;
  }