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 EXPORT_SYMBOL(nf_ct_ext_destroy); 39 40 void *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 } 89 EXPORT_SYMBOL(nf_ct_ext_add); 90 91 /* This MUST be called in process context. */ 92 int 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); 103 out: 104 mutex_unlock(&nf_ct_ext_type_mutex); 105 return ret; 106 } 107 EXPORT_SYMBOL_GPL(nf_ct_extend_register); 108 109 /* This MUST be called in process context. */ 110 void 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 } 117 EXPORT_SYMBOL_GPL(nf_ct_extend_unregister); 118