LXR linux/net/netfilter/nf_conntrack

   1// SPDX-License-Identifier: GPL-2.0-or-later
   2/* Structure dynamic extension infrastructure
   3 * Copyright (C) 2004 Rusty Russell IBM Corporation
   4 * Copyright (C) 2007 Netfilter Core Team <coreteam@netfilter.org>
   5 * Copyright (C) 2007 USAGI/WIDE Project <http://www.linux-ipv6.org>
   6 */
   7#include <linux/kernel.h>
   8#include <linux/kmemleak.h>
   9#include <linux/module.h>
  10#include <linux/mutex.h>
  11#include <linux/rcupdate.h>
  12#include <linux/slab.h>
  13#include <linux/skbuff.h>
  14#include <net/netfilter/nf_conntrack_extend.h>
  15
  16static struct nf_ct_ext_type __rcu *nf_ct_ext_types[NF_CT_EXT_NUM];
  17static DEFINE_MUTEX(nf_ct_ext_type_mutex);
  18#define NF_CT_EXT_PREALLOC      128u /* conntrack events are on by default */
  19
  20void nf_ct_ext_destroy(struct nf_conn *ct)
  21{
  22        unsigned int i;
  23        struct nf_ct_ext_type *t;
  24
  25        for (i = 0; i < NF_CT_EXT_NUM; i++) {
  26                rcu_read_lock();
  27                t = rcu_dereference(nf_ct_ext_types[i]);
  28
  29                /* Here the nf_ct_ext_type might have been unregisterd.
  30                 * I.e., it has responsible to cleanup private
  31                 * area in all conntracks when it is unregisterd.
  32                 */
  33                if (t && t->destroy)
  34                        t->destroy(ct);
  35                rcu_read_unlock();
  36        }
  37}
  38EXPORT_SYMBOL(nf_ct_ext_destroy);
  39
  40void *nf_ct_ext_add(struct nf_conn *ct, enum nf_ct_ext_id id, gfp_t gfp)
  41{
  42        unsigned int newlen, newoff, oldlen, alloc;
  43        struct nf_ct_ext *old, *new;
  44        struct nf_ct_ext_type *t;
  45
  46        /* Conntrack must not be confirmed to avoid races on reallocation. */
  47        WARN_ON(nf_ct_is_confirmed(ct));
  48
  49        old = ct->ext;
  50
  51        if (old) {
  52                if (__nf_ct_ext_exist(old, id))
  53                        return NULL;
  54                oldlen = old->len;
  55        } else {
  56                oldlen = sizeof(*new);
  57        }
  58
  59        rcu_read_lock();
  60        t = rcu_dereference(nf_ct_ext_types[id]);
  61        if (!t) {
  62                rcu_read_unlock();
  63                return NULL;
  64        }
  65
  66        newoff = ALIGN(oldlen, t->align);
  67        newlen = newoff + t->len;
  68        rcu_read_unlock();
  69
  70        alloc = max(newlen, NF_CT_EXT_PREALLOC);
  71        kmemleak_not_leak(old);
  72        new = __krealloc(old, alloc, gfp);
  73        if (!new)
  74                return NULL;
  75
  76        if (!old) {
  77                memset(new->offset, 0, sizeof(new->offset));
  78                ct->ext = new;
  79        } else if (new != old) {
  80                kfree_rcu(old, rcu);
  81                rcu_assign_pointer(ct->ext, new);
  82        }
  83
  84        new->offset[id] = newoff;
  85        new->len = newlen;
  86        memset((void *)new + newoff, 0, newlen - newoff);
  87        return (void *)new + newoff;
  88}
  89EXPORT_SYMBOL(nf_ct_ext_add);
  90
  91/* This MUST be called in process context. */
  92int nf_ct_extend_register(const struct nf_ct_ext_type *type)
  93{
  94        int ret = 0;
  95
  96        mutex_lock(&nf_ct_ext_type_mutex);
  97        if (nf_ct_ext_types[type->id]) {
  98                ret = -EBUSY;
  99                goto out;
 100        }
 101
 102        rcu_assign_pointer(nf_ct_ext_types[type->id], type);
 103out:
 104        mutex_unlock(&nf_ct_ext_type_mutex);
 105        return ret;
 106}
 107EXPORT_SYMBOL_GPL(nf_ct_extend_register);
 108
 109/* This MUST be called in process context. */
 110void nf_ct_extend_unregister(const struct nf_ct_ext_type *type)
 111{
 112        mutex_lock(&nf_ct_ext_type_mutex);
 113        RCU_INIT_POINTER(nf_ct_ext_types[type->id], NULL);
 114        mutex_unlock(&nf_ct_ext_type_mutex);
 115        synchronize_rcu();
 116}
 117EXPORT_SYMBOL_GPL(nf_ct_extend_unregister);
 118