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/kmemleak.h> 13 #include <linux/module.h> 14 #include <linux/mutex.h> 15 #include <linux/rcupdate.h> 16 #include <linux/slab.h> 17 #include <linux/skbuff.h> 18 #include <net/netfilter/nf_conntrack_extend.h> 19 20 static struct nf_ct_ext_type __rcu *nf_ct_ext_types[NF_CT_EXT_NUM]; 21 static DEFINE_MUTEX(nf_ct_ext_type_mutex); 22 #define NF_CT_EXT_PREALLOC 128u /* conntrack events are on by default */ 23 24 void nf_ct_ext_destroy(struct nf_conn *ct) 25 { 26 unsigned int i; 27 struct nf_ct_ext_type *t; 28 29 for (i = 0; i < NF_CT_EXT_NUM; i++) { 30 rcu_read_lock(); 31 t = rcu_dereference(nf_ct_ext_types[i]); 32 33 /* Here the nf_ct_ext_type might have been unregisterd. 34 * I.e., it has responsible to cleanup private 35 * area in all conntracks when it is unregisterd. 36 */ 37 if (t && t->destroy) 38 t->destroy(ct); 39 rcu_read_unlock(); 40 } 41 } 42 EXPORT_SYMBOL(nf_ct_ext_destroy); 43 44 void *nf_ct_ext_add(struct nf_conn *ct, enum nf_ct_ext_id id, gfp_t gfp) 45 { 46 unsigned int newlen, newoff, oldlen, alloc; 47 struct nf_ct_ext *old, *new; 48 struct nf_ct_ext_type *t; 49 50 /* Conntrack must not be confirmed to avoid races on reallocation. */ 51 WARN_ON(nf_ct_is_confirmed(ct)); 52 53 old = ct->ext; 54 55 if (old) { 56 if (__nf_ct_ext_exist(old, id)) 57 return NULL; 58 oldlen = old->len; 59 } else { 60 oldlen = sizeof(*new); 61 } 62 63 rcu_read_lock(); 64 t = rcu_dereference(nf_ct_ext_types[id]); 65 if (!t) { 66 rcu_read_unlock(); 67 return NULL; 68 } 69 70 newoff = ALIGN(oldlen, t->align); 71 newlen = newoff + t->len; 72 rcu_read_unlock(); 73 74 alloc = max(newlen, NF_CT_EXT_PREALLOC); 75 kmemleak_not_leak(old); 76 new = __krealloc(old, alloc, gfp); 77 if (!new) 78 return NULL; 79 80 if (!old) { 81 memset(new->offset, 0, sizeof(new->offset)); 82 ct->ext = new; 83 } else if (new != old) { 84 kfree_rcu(old, rcu); 85 rcu_assign_pointer(ct->ext, new); 86 } 87 88 new->offset[id] = newoff; 89 new->len = newlen; 90 memset((void *)new + newoff, 0, newlen - newoff); 91 return (void *)new + newoff; 92 } 93 EXPORT_SYMBOL(nf_ct_ext_add); 94 95 /* This MUST be called in process context. */ 96 int nf_ct_extend_register(const struct nf_ct_ext_type *type) 97 { 98 int ret = 0; 99 100 mutex_lock(&nf_ct_ext_type_mutex); 101 if (nf_ct_ext_types[type->id]) { 102 ret = -EBUSY; 103 goto out; 104 } 105 106 rcu_assign_pointer(nf_ct_ext_types[type->id], type); 107 out: 108 mutex_unlock(&nf_ct_ext_type_mutex); 109 return ret; 110 } 111 EXPORT_SYMBOL_GPL(nf_ct_extend_register); 112 113 /* This MUST be called in process context. */ 114 void nf_ct_extend_unregister(const struct nf_ct_ext_type *type) 115 { 116 mutex_lock(&nf_ct_ext_type_mutex); 117 RCU_INIT_POINTER(nf_ct_ext_types[type->id], NULL); 118 mutex_unlock(&nf_ct_ext_type_mutex); 119 synchronize_rcu(); 120 } 121 EXPORT_SYMBOL_GPL(nf_ct_extend_unregister); 122