Add helper functions for sysctl registration with optional instantiating of common path elements (like net/netfilter) and use it for support for automatic registation of conntrack protocol sysctls. Signed-off-by: Patrick McHardy <kaber@trash.net>
370 lines
8.6 KiB
C
370 lines
8.6 KiB
C
/* L3/L4 protocol support for nf_conntrack. */
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/* (C) 1999-2001 Paul `Rusty' Russell
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* (C) 2002-2006 Netfilter Core Team <coreteam@netfilter.org>
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* (C) 2003,2004 USAGI/WIDE Project <http://www.linux-ipv6.org>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*/
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#include <linux/types.h>
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#include <linux/netfilter.h>
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#include <linux/module.h>
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#include <linux/mutex.h>
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#include <linux/skbuff.h>
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#include <linux/vmalloc.h>
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#include <linux/stddef.h>
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#include <linux/err.h>
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#include <linux/percpu.h>
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#include <linux/moduleparam.h>
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#include <linux/notifier.h>
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#include <linux/kernel.h>
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#include <linux/netdevice.h>
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#include <net/netfilter/nf_conntrack.h>
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#include <net/netfilter/nf_conntrack_l3proto.h>
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#include <net/netfilter/nf_conntrack_l4proto.h>
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#include <net/netfilter/nf_conntrack_core.h>
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struct nf_conntrack_l4proto **nf_ct_protos[PF_MAX] __read_mostly;
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struct nf_conntrack_l3proto *nf_ct_l3protos[AF_MAX] __read_mostly;
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#ifdef CONFIG_SYSCTL
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static DEFINE_MUTEX(nf_ct_proto_sysctl_mutex);
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static int
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nf_ct_register_sysctl(struct ctl_table_header **header, struct ctl_table *path,
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struct ctl_table *table, unsigned int *users)
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{
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if (*header == NULL) {
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*header = nf_register_sysctl_table(path, table);
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if (*header == NULL)
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return -ENOMEM;
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}
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if (users != NULL)
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(*users)++;
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return 0;
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}
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static void
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nf_ct_unregister_sysctl(struct ctl_table_header **header,
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struct ctl_table *table, unsigned int *users)
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{
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if (users != NULL && --*users > 0)
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return;
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nf_unregister_sysctl_table(*header, table);
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*header = NULL;
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}
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#endif
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struct nf_conntrack_l4proto *
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__nf_ct_l4proto_find(u_int16_t l3proto, u_int8_t l4proto)
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{
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if (unlikely(l3proto >= AF_MAX || nf_ct_protos[l3proto] == NULL))
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return &nf_conntrack_l4proto_generic;
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return nf_ct_protos[l3proto][l4proto];
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}
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/* this is guaranteed to always return a valid protocol helper, since
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* it falls back to generic_protocol */
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struct nf_conntrack_l4proto *
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nf_ct_l4proto_find_get(u_int16_t l3proto, u_int8_t l4proto)
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{
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struct nf_conntrack_l4proto *p;
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preempt_disable();
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p = __nf_ct_l4proto_find(l3proto, l4proto);
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if (!try_module_get(p->me))
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p = &nf_conntrack_l4proto_generic;
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preempt_enable();
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return p;
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}
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void nf_ct_l4proto_put(struct nf_conntrack_l4proto *p)
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{
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module_put(p->me);
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}
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struct nf_conntrack_l3proto *
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nf_ct_l3proto_find_get(u_int16_t l3proto)
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{
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struct nf_conntrack_l3proto *p;
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preempt_disable();
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p = __nf_ct_l3proto_find(l3proto);
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if (!try_module_get(p->me))
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p = &nf_conntrack_l3proto_generic;
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preempt_enable();
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return p;
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}
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void nf_ct_l3proto_put(struct nf_conntrack_l3proto *p)
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{
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module_put(p->me);
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}
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int
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nf_ct_l3proto_try_module_get(unsigned short l3proto)
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{
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int ret;
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struct nf_conntrack_l3proto *p;
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retry: p = nf_ct_l3proto_find_get(l3proto);
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if (p == &nf_conntrack_l3proto_generic) {
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ret = request_module("nf_conntrack-%d", l3proto);
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if (!ret)
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goto retry;
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return -EPROTOTYPE;
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}
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return 0;
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}
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void nf_ct_l3proto_module_put(unsigned short l3proto)
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{
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struct nf_conntrack_l3proto *p;
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preempt_disable();
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p = __nf_ct_l3proto_find(l3proto);
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preempt_enable();
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module_put(p->me);
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}
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static int kill_l3proto(struct nf_conn *i, void *data)
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{
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return (i->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.l3num ==
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((struct nf_conntrack_l3proto *)data)->l3proto);
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}
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static int kill_l4proto(struct nf_conn *i, void *data)
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{
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struct nf_conntrack_l4proto *l4proto;
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l4proto = (struct nf_conntrack_l4proto *)data;
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return (i->tuplehash[IP_CT_DIR_ORIGINAL].tuple.dst.protonum ==
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l4proto->l4proto) &&
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(i->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.l3num ==
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l4proto->l3proto);
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}
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static int nf_ct_l3proto_register_sysctl(struct nf_conntrack_l3proto *l3proto)
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{
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int err = 0;
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#ifdef CONFIG_SYSCTL
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mutex_lock(&nf_ct_proto_sysctl_mutex);
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if (l3proto->ctl_table != NULL) {
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err = nf_ct_register_sysctl(&l3proto->ctl_table_header,
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l3proto->ctl_table_path,
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l3proto->ctl_table, NULL);
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}
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mutex_unlock(&nf_ct_proto_sysctl_mutex);
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#endif
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return err;
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}
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static void nf_ct_l3proto_unregister_sysctl(struct nf_conntrack_l3proto *l3proto)
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{
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#ifdef CONFIG_SYSCTL
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mutex_lock(&nf_ct_proto_sysctl_mutex);
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if (l3proto->ctl_table_header != NULL)
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nf_ct_unregister_sysctl(&l3proto->ctl_table_header,
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l3proto->ctl_table, NULL);
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mutex_unlock(&nf_ct_proto_sysctl_mutex);
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#endif
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}
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int nf_conntrack_l3proto_register(struct nf_conntrack_l3proto *proto)
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{
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int ret = 0;
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if (proto->l3proto >= AF_MAX) {
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ret = -EBUSY;
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goto out;
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}
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write_lock_bh(&nf_conntrack_lock);
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if (nf_ct_l3protos[proto->l3proto] != &nf_conntrack_l3proto_generic) {
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ret = -EBUSY;
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goto out_unlock;
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}
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nf_ct_l3protos[proto->l3proto] = proto;
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write_unlock_bh(&nf_conntrack_lock);
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ret = nf_ct_l3proto_register_sysctl(proto);
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if (ret < 0)
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nf_conntrack_l3proto_unregister(proto);
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return ret;
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out_unlock:
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write_unlock_bh(&nf_conntrack_lock);
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out:
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return ret;
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}
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int nf_conntrack_l3proto_unregister(struct nf_conntrack_l3proto *proto)
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{
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int ret = 0;
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if (proto->l3proto >= AF_MAX) {
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ret = -EBUSY;
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goto out;
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}
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write_lock_bh(&nf_conntrack_lock);
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if (nf_ct_l3protos[proto->l3proto] != proto) {
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write_unlock_bh(&nf_conntrack_lock);
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ret = -EBUSY;
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goto out;
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}
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nf_ct_l3protos[proto->l3proto] = &nf_conntrack_l3proto_generic;
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write_unlock_bh(&nf_conntrack_lock);
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nf_ct_l3proto_unregister_sysctl(proto);
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/* Somebody could be still looking at the proto in bh. */
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synchronize_net();
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/* Remove all contrack entries for this protocol */
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nf_ct_iterate_cleanup(kill_l3proto, proto);
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out:
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return ret;
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}
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static int nf_ct_l4proto_register_sysctl(struct nf_conntrack_l4proto *l4proto)
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{
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int err = 0;
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#ifdef CONFIG_SYSCTL
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mutex_lock(&nf_ct_proto_sysctl_mutex);
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if (l4proto->ctl_table != NULL) {
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err = nf_ct_register_sysctl(l4proto->ctl_table_header,
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nf_net_netfilter_sysctl_path,
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l4proto->ctl_table,
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l4proto->ctl_table_users);
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}
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mutex_unlock(&nf_ct_proto_sysctl_mutex);
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#endif
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return err;
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}
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static void nf_ct_l4proto_unregister_sysctl(struct nf_conntrack_l4proto *l4proto)
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{
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#ifdef CONFIG_SYSCTL
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mutex_lock(&nf_ct_proto_sysctl_mutex);
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if (l4proto->ctl_table_header != NULL &&
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*l4proto->ctl_table_header != NULL)
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nf_ct_unregister_sysctl(l4proto->ctl_table_header,
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l4proto->ctl_table,
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l4proto->ctl_table_users);
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mutex_unlock(&nf_ct_proto_sysctl_mutex);
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#endif
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}
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/* FIXME: Allow NULL functions and sub in pointers to generic for
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them. --RR */
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int nf_conntrack_l4proto_register(struct nf_conntrack_l4proto *l4proto)
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{
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int ret = 0;
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if (l4proto->l3proto >= PF_MAX) {
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ret = -EBUSY;
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goto out;
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}
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retry:
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write_lock_bh(&nf_conntrack_lock);
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if (nf_ct_protos[l4proto->l3proto]) {
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if (nf_ct_protos[l4proto->l3proto][l4proto->l4proto]
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!= &nf_conntrack_l4proto_generic) {
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ret = -EBUSY;
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goto out_unlock;
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}
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} else {
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/* l3proto may be loaded latter. */
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struct nf_conntrack_l4proto **proto_array;
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int i;
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write_unlock_bh(&nf_conntrack_lock);
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proto_array = (struct nf_conntrack_l4proto **)
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kmalloc(MAX_NF_CT_PROTO *
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sizeof(struct nf_conntrack_l4proto *),
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GFP_KERNEL);
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if (proto_array == NULL) {
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ret = -ENOMEM;
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goto out;
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}
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for (i = 0; i < MAX_NF_CT_PROTO; i++)
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proto_array[i] = &nf_conntrack_l4proto_generic;
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write_lock_bh(&nf_conntrack_lock);
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if (nf_ct_protos[l4proto->l3proto]) {
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/* bad timing, but no problem */
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write_unlock_bh(&nf_conntrack_lock);
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kfree(proto_array);
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} else {
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nf_ct_protos[l4proto->l3proto] = proto_array;
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write_unlock_bh(&nf_conntrack_lock);
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}
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/*
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* Just once because array is never freed until unloading
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* nf_conntrack.ko
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*/
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goto retry;
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}
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nf_ct_protos[l4proto->l3proto][l4proto->l4proto] = l4proto;
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write_unlock_bh(&nf_conntrack_lock);
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ret = nf_ct_l4proto_register_sysctl(l4proto);
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if (ret < 0)
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nf_conntrack_l4proto_unregister(l4proto);
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return ret;
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out_unlock:
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write_unlock_bh(&nf_conntrack_lock);
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out:
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return ret;
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}
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int nf_conntrack_l4proto_unregister(struct nf_conntrack_l4proto *l4proto)
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{
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int ret = 0;
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if (l4proto->l3proto >= PF_MAX) {
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ret = -EBUSY;
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goto out;
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}
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write_lock_bh(&nf_conntrack_lock);
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if (nf_ct_protos[l4proto->l3proto][l4proto->l4proto]
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!= l4proto) {
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write_unlock_bh(&nf_conntrack_lock);
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ret = -EBUSY;
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goto out;
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}
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nf_ct_protos[l4proto->l3proto][l4proto->l4proto]
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= &nf_conntrack_l4proto_generic;
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write_unlock_bh(&nf_conntrack_lock);
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nf_ct_l4proto_unregister_sysctl(l4proto);
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/* Somebody could be still looking at the proto in bh. */
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synchronize_net();
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/* Remove all contrack entries for this protocol */
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nf_ct_iterate_cleanup(kill_l4proto, l4proto);
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out:
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return ret;
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}
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