1 /* Structure dynamic extension infrastructure 2 * Copyright (C) 2004 Rusty Russell IBM Corporation 3 * Copyright (C) 2007 Netfilter Core Team <coreteam@netfilter.org> 4 * Copyright (C) 2007 USAGI/WIDE Project <http://www.linux-ipv6.org> 5 * 6 * This program is free software; you can redistribute it and/or 7 * modify it under the terms of the GNU General Public License 8 * as published by the Free Software Foundation; either version 9 * 2 of the License, or (at your option) any later version. 10 */ 11 #include <linux/kernel.h> 12 #include <linux/module.h> 13 #include <linux/mutex.h> 14 #include <linux/rcupdate.h> 15 #include <linux/slab.h> 16 #include <linux/skbuff.h> 17 #include <net/netfilter/nf_conntrack_extend.h> 18 19 static struct nf_ct_ext_type __rcu *nf_ct_ext_types[NF_CT_EXT_NUM]; 20 static DEFINE_MUTEX(nf_ct_ext_type_mutex); 21 #define NF_CT_EXT_PREALLOC 128u /* conntrack events are on by default */ 22 23 void nf_ct_ext_destroy(struct nf_conn *ct) 24 { 25 unsigned int i; 26 struct nf_ct_ext_type *t; 27 28 for (i = 0; i < NF_CT_EXT_NUM; i++) { 29 rcu_read_lock(); 30 t = rcu_dereference(nf_ct_ext_types[i]); 31 32 /* Here the nf_ct_ext_type might have been unregisterd. 33 * I.e., it has responsible to cleanup private 34 * area in all conntracks when it is unregisterd. 35 */ 36 if (t && t->destroy) 37 t->destroy(ct); 38 rcu_read_unlock(); 39 } 40 } 41 EXPORT_SYMBOL(nf_ct_ext_destroy); 42 43 void *nf_ct_ext_add(struct nf_conn *ct, enum nf_ct_ext_id id, gfp_t gfp) 44 { 45 unsigned int newlen, newoff, oldlen, alloc; 46 struct nf_ct_ext *old, *new; 47 struct nf_ct_ext_type *t; 48 49 /* Conntrack must not be confirmed to avoid races on reallocation. */ 50 WARN_ON(nf_ct_is_confirmed(ct)); 51 52 old = ct->ext; 53 54 if (old) { 55 if (__nf_ct_ext_exist(old, id)) 56 return NULL; 57 oldlen = old->len; 58 } else { 59 oldlen = sizeof(*new); 60 } 61 62 rcu_read_lock(); 63 t = rcu_dereference(nf_ct_ext_types[id]); 64 if (!t) { 65 rcu_read_unlock(); 66 return NULL; 67 } 68 69 newoff = ALIGN(oldlen, t->align); 70 newlen = newoff + t->len; 71 rcu_read_unlock(); 72 73 alloc = max(newlen, NF_CT_EXT_PREALLOC); 74 new = __krealloc(old, alloc, gfp); 75 if (!new) 76 return NULL; 77 78 if (!old) { 79 memset(new->offset, 0, sizeof(new->offset)); 80 ct->ext = new; 81 } else if (new != old) { 82 kfree_rcu(old, rcu); 83 rcu_assign_pointer(ct->ext, new); 84 } 85 86 new->offset[id] = newoff; 87 new->len = newlen; 88 memset((void *)new + newoff, 0, newlen - newoff); 89 return (void *)new + newoff; 90 } 91 EXPORT_SYMBOL(nf_ct_ext_add); 92 93 /* This MUST be called in process context. */ 94 int nf_ct_extend_register(const struct nf_ct_ext_type *type) 95 { 96 int ret = 0; 97 98 mutex_lock(&nf_ct_ext_type_mutex); 99 if (nf_ct_ext_types[type->id]) { 100 ret = -EBUSY; 101 goto out; 102 } 103 104 rcu_assign_pointer(nf_ct_ext_types[type->id], type); 105 out: 106 mutex_unlock(&nf_ct_ext_type_mutex); 107 return ret; 108 } 109 EXPORT_SYMBOL_GPL(nf_ct_extend_register); 110 111 /* This MUST be called in process context. */ 112 void nf_ct_extend_unregister(const struct nf_ct_ext_type *type) 113 { 114 mutex_lock(&nf_ct_ext_type_mutex); 115 RCU_INIT_POINTER(nf_ct_ext_types[type->id], NULL); 116 mutex_unlock(&nf_ct_ext_type_mutex); 117 synchronize_rcu(); 118 } 119 EXPORT_SYMBOL_GPL(nf_ct_extend_unregister); 120