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 16 static struct nf_ct_ext_type __rcu *nf_ct_ext_types[NF_CT_EXT_NUM]; 17 static DEFINE_MUTEX(nf_ct_ext_type_mutex); 18 #define NF_CT_EXT_PREALLOC 128u /* conntrack events are on by default */ 19 20 void 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 38 kfree(ct->ext); 39 } 40 41 void *nf_ct_ext_add(struct nf_conn *ct, enum nf_ct_ext_id id, gfp_t gfp) 42 { 43 unsigned int newlen, newoff, oldlen, alloc; 44 struct nf_ct_ext_type *t; 45 struct nf_ct_ext *new; 46 47 /* Conntrack must not be confirmed to avoid races on reallocation. */ 48 WARN_ON(nf_ct_is_confirmed(ct)); 49 50 51 if (ct->ext) { 52 const struct nf_ct_ext *old = ct->ext; 53 54 if (__nf_ct_ext_exist(old, id)) 55 return NULL; 56 oldlen = old->len; 57 } else { 58 oldlen = sizeof(*new); 59 } 60 61 rcu_read_lock(); 62 t = rcu_dereference(nf_ct_ext_types[id]); 63 if (!t) { 64 rcu_read_unlock(); 65 return NULL; 66 } 67 68 newoff = ALIGN(oldlen, t->align); 69 newlen = newoff + t->len; 70 rcu_read_unlock(); 71 72 alloc = max(newlen, NF_CT_EXT_PREALLOC); 73 new = krealloc(ct->ext, alloc, gfp); 74 if (!new) 75 return NULL; 76 77 if (!ct->ext) 78 memset(new->offset, 0, sizeof(new->offset)); 79 80 new->offset[id] = newoff; 81 new->len = newlen; 82 memset((void *)new + newoff, 0, newlen - newoff); 83 84 ct->ext = new; 85 return (void *)new + newoff; 86 } 87 EXPORT_SYMBOL(nf_ct_ext_add); 88 89 /* This MUST be called in process context. */ 90 int nf_ct_extend_register(const struct nf_ct_ext_type *type) 91 { 92 int ret = 0; 93 94 mutex_lock(&nf_ct_ext_type_mutex); 95 if (nf_ct_ext_types[type->id]) { 96 ret = -EBUSY; 97 goto out; 98 } 99 100 rcu_assign_pointer(nf_ct_ext_types[type->id], type); 101 out: 102 mutex_unlock(&nf_ct_ext_type_mutex); 103 return ret; 104 } 105 EXPORT_SYMBOL_GPL(nf_ct_extend_register); 106 107 /* This MUST be called in process context. */ 108 void nf_ct_extend_unregister(const struct nf_ct_ext_type *type) 109 { 110 mutex_lock(&nf_ct_ext_type_mutex); 111 RCU_INIT_POINTER(nf_ct_ext_types[type->id], NULL); 112 mutex_unlock(&nf_ct_ext_type_mutex); 113 synchronize_rcu(); 114 } 115 EXPORT_SYMBOL_GPL(nf_ct_extend_unregister); 116