// SPDX-License-Identifier: GPL-2.0-or-later

  /* Structure dynamic extension infrastructure
   * Copyright (C) 2004 Rusty Russell IBM Corporation
   * Copyright (C) 2007 Netfilter Core Team <coreteam@netfilter.org>
   * Copyright (C) 2007 USAGI/WIDE Project <http://www.linux-ipv6.org>

   */
  #include <linux/kernel.h>

  #include <linux/kmemleak.h>

  #include <linux/module.h>
  #include <linux/mutex.h>
  #include <linux/rcupdate.h>
  #include <linux/slab.h>
  #include <linux/skbuff.h>
  #include <net/netfilter/nf_conntrack_extend.h>

  static struct nf_ct_ext_type __rcu *nf_ct_ext_types[NF_CT_EXT_NUM];

  static DEFINE_MUTEX(nf_ct_ext_type_mutex);

  #define NF_CT_EXT_PREALLOC	128u /* conntrack events are on by default */

  void nf_ct_ext_destroy(struct nf_conn *ct)

  {
  	unsigned int i;
  	struct nf_ct_ext_type *t;
  
  	for (i = 0; i < NF_CT_EXT_NUM; i++) {

  		rcu_read_lock();
  		t = rcu_dereference(nf_ct_ext_types[i]);
  
  		/* Here the nf_ct_ext_type might have been unregisterd.
  		 * I.e., it has responsible to cleanup private
  		 * area in all conntracks when it is unregisterd.
  		 */
  		if (t && t->destroy)
  			t->destroy(ct);
  		rcu_read_unlock();
  	}

  
  	kfree(ct->ext);

  }

  EXPORT_SYMBOL(nf_ct_ext_destroy);

  void *nf_ct_ext_add(struct nf_conn *ct, enum nf_ct_ext_id id, gfp_t gfp)

  {

  	unsigned int newlen, newoff, oldlen, alloc;

  	struct nf_ct_ext_type *t;

  	struct nf_ct_ext *new;

  	/* Conntrack must not be confirmed to avoid races on reallocation. */

  	WARN_ON(nf_ct_is_confirmed(ct));

  	if (ct->ext) {
  		const struct nf_ct_ext *old = ct->ext;

  		if (__nf_ct_ext_exist(old, id))
  			return NULL;
  		oldlen = old->len;
  	} else {
  		oldlen = sizeof(*new);
  	}

  
  	rcu_read_lock();
  	t = rcu_dereference(nf_ct_ext_types[id]);

  	if (!t) {
  		rcu_read_unlock();
  		return NULL;
  	}

  	newoff = ALIGN(oldlen, t->align);

  	newlen = newoff + t->len;

  	rcu_read_unlock();

  	alloc = max(newlen, NF_CT_EXT_PREALLOC);

  	new = krealloc(ct->ext, alloc, gfp);

  	if (!new)
  		return NULL;

  	if (!ct->ext)

  		memset(new->offset, 0, sizeof(new->offset));

  	new->offset[id] = newoff;
  	new->len = newlen;
  	memset((void *)new + newoff, 0, newlen - newoff);

  
  	ct->ext = new;

  	return (void *)new + newoff;

  }

  EXPORT_SYMBOL(nf_ct_ext_add);

  /* This MUST be called in process context. */

  int nf_ct_extend_register(const struct nf_ct_ext_type *type)

  {
  	int ret = 0;
  
  	mutex_lock(&nf_ct_ext_type_mutex);
  	if (nf_ct_ext_types[type->id]) {
  		ret = -EBUSY;
  		goto out;
  	}

  	rcu_assign_pointer(nf_ct_ext_types[type->id], type);

  out:
  	mutex_unlock(&nf_ct_ext_type_mutex);
  	return ret;
  }
  EXPORT_SYMBOL_GPL(nf_ct_extend_register);
  
  /* This MUST be called in process context. */

  void nf_ct_extend_unregister(const struct nf_ct_ext_type *type)

  {
  	mutex_lock(&nf_ct_ext_type_mutex);

  	RCU_INIT_POINTER(nf_ct_ext_types[type->id], NULL);

  	mutex_unlock(&nf_ct_ext_type_mutex);

  	synchronize_rcu();

  }
  EXPORT_SYMBOL_GPL(nf_ct_extend_unregister);