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- /* Structure dynamic extension infrastructure
- * Copyright (C) 2004 Rusty Russell IBM Corporation
- * Copyright (C) 2007 Netfilter Core Team <coreteam@netfilter.org>
- * Copyright (C) 2007 USAGI/WIDE Project <http://www.linux-ipv6.org>
- *
- * This program is free software; you can redistribute it and/or
- * modify it under the terms of the GNU General Public License
- * as published by the Free Software Foundation; either version
- * 2 of the License, or (at your option) any later version.
- */
- #include <linux/kernel.h>
- #include <linux/module.h>
- #include <linux/mutex.h>
- #include <linux/rcupdate.h>
- #include <linux/slab.h>
- #include <linux/skbuff.h>
- #include <net/netfilter/nf_conntrack_extend.h>
- static struct nf_ct_ext_type __rcu *nf_ct_ext_types[NF_CT_EXT_NUM];
- static DEFINE_MUTEX(nf_ct_ext_type_mutex);
- void __nf_ct_ext_destroy(struct nf_conn *ct)
- {
- unsigned int i;
- struct nf_ct_ext_type *t;
- struct nf_ct_ext *ext = ct->ext;
- for (i = 0; i < NF_CT_EXT_NUM; i++) {
- if (!__nf_ct_ext_exist(ext, i))
- continue;
- rcu_read_lock();
- t = rcu_dereference(nf_ct_ext_types[i]);
- /* Here the nf_ct_ext_type might have been unregisterd.
- * I.e., it has responsible to cleanup private
- * area in all conntracks when it is unregisterd.
- */
- if (t && t->destroy)
- t->destroy(ct);
- rcu_read_unlock();
- }
- }
- EXPORT_SYMBOL(__nf_ct_ext_destroy);
- static void *
- nf_ct_ext_create(struct nf_ct_ext **ext, enum nf_ct_ext_id id,
- size_t var_alloc_len, gfp_t gfp)
- {
- unsigned int off, len;
- struct nf_ct_ext_type *t;
- size_t alloc_size;
- rcu_read_lock();
- t = rcu_dereference(nf_ct_ext_types[id]);
- if (!t) {
- rcu_read_unlock();
- return NULL;
- }
- off = ALIGN(sizeof(struct nf_ct_ext), t->align);
- len = off + t->len + var_alloc_len;
- alloc_size = t->alloc_size + var_alloc_len;
- rcu_read_unlock();
- *ext = kzalloc(alloc_size, gfp);
- if (!*ext)
- return NULL;
- (*ext)->offset[id] = off;
- (*ext)->len = len;
- return (void *)(*ext) + off;
- }
- void *__nf_ct_ext_add_length(struct nf_conn *ct, enum nf_ct_ext_id id,
- size_t var_alloc_len, gfp_t gfp)
- {
- struct nf_ct_ext *old, *new;
- int i, newlen, newoff;
- struct nf_ct_ext_type *t;
- /* Conntrack must not be confirmed to avoid races on reallocation. */
- NF_CT_ASSERT(!nf_ct_is_confirmed(ct));
- old = ct->ext;
- if (!old)
- return nf_ct_ext_create(&ct->ext, id, var_alloc_len, gfp);
- if (__nf_ct_ext_exist(old, id))
- return NULL;
- rcu_read_lock();
- t = rcu_dereference(nf_ct_ext_types[id]);
- if (!t) {
- rcu_read_unlock();
- return NULL;
- }
- newoff = ALIGN(old->len, t->align);
- newlen = newoff + t->len + var_alloc_len;
- rcu_read_unlock();
- new = __krealloc(old, newlen, gfp);
- if (!new)
- return NULL;
- if (new != old) {
- for (i = 0; i < NF_CT_EXT_NUM; i++) {
- if (!__nf_ct_ext_exist(old, i))
- continue;
- rcu_read_lock();
- t = rcu_dereference(nf_ct_ext_types[i]);
- if (t && t->move)
- t->move((void *)new + new->offset[i],
- (void *)old + old->offset[i]);
- rcu_read_unlock();
- }
- kfree_rcu(old, rcu);
- ct->ext = new;
- }
- new->offset[id] = newoff;
- new->len = newlen;
- memset((void *)new + newoff, 0, newlen - newoff);
- return (void *)new + newoff;
- }
- EXPORT_SYMBOL(__nf_ct_ext_add_length);
- static void update_alloc_size(struct nf_ct_ext_type *type)
- {
- int i, j;
- struct nf_ct_ext_type *t1, *t2;
- enum nf_ct_ext_id min = 0, max = NF_CT_EXT_NUM - 1;
- /* unnecessary to update all types */
- if ((type->flags & NF_CT_EXT_F_PREALLOC) == 0) {
- min = type->id;
- max = type->id;
- }
- /* This assumes that extended areas in conntrack for the types
- whose NF_CT_EXT_F_PREALLOC bit set are allocated in order */
- for (i = min; i <= max; i++) {
- t1 = rcu_dereference_protected(nf_ct_ext_types[i],
- lockdep_is_held(&nf_ct_ext_type_mutex));
- if (!t1)
- continue;
- t1->alloc_size = ALIGN(sizeof(struct nf_ct_ext), t1->align) +
- t1->len;
- for (j = 0; j < NF_CT_EXT_NUM; j++) {
- t2 = rcu_dereference_protected(nf_ct_ext_types[j],
- lockdep_is_held(&nf_ct_ext_type_mutex));
- if (t2 == NULL || t2 == t1 ||
- (t2->flags & NF_CT_EXT_F_PREALLOC) == 0)
- continue;
- t1->alloc_size = ALIGN(t1->alloc_size, t2->align)
- + t2->len;
- }
- }
- }
- /* This MUST be called in process context. */
- int nf_ct_extend_register(struct nf_ct_ext_type *type)
- {
- int ret = 0;
- mutex_lock(&nf_ct_ext_type_mutex);
- if (nf_ct_ext_types[type->id]) {
- ret = -EBUSY;
- goto out;
- }
- /* This ensures that nf_ct_ext_create() can allocate enough area
- before updating alloc_size */
- type->alloc_size = ALIGN(sizeof(struct nf_ct_ext), type->align)
- + type->len;
- rcu_assign_pointer(nf_ct_ext_types[type->id], type);
- update_alloc_size(type);
- out:
- mutex_unlock(&nf_ct_ext_type_mutex);
- return ret;
- }
- EXPORT_SYMBOL_GPL(nf_ct_extend_register);
- /* This MUST be called in process context. */
- void nf_ct_extend_unregister(struct nf_ct_ext_type *type)
- {
- mutex_lock(&nf_ct_ext_type_mutex);
- RCU_INIT_POINTER(nf_ct_ext_types[type->id], NULL);
- update_alloc_size(type);
- mutex_unlock(&nf_ct_ext_type_mutex);
- synchronize_rcu();
- }
- EXPORT_SYMBOL_GPL(nf_ct_extend_unregister);
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