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![Florian Westphal](/assets/img/avatar_default.png)
Discussion during NFWS 2017 in Faro has shown that the current
conntrack behaviour is unreasonable.
Even if conntrack module is loaded on behalf of a single net namespace,
its turned on for all namespaces, which is expensive. Commit
481fa37347
("netfilter: conntrack: add nf_conntrack_default_on sysctl")
attempted to provide an alternative to the 'default on' behaviour by
adding a sysctl to change it.
However, as Eric points out, the sysctl only becomes available
once the module is loaded, and then its too late.
So we either have to move the sysctl to the core, or, alternatively,
change conntrack to become active only once the rule set requires this.
This does the latter, conntrack is only enabled when a rule needs it.
Reported-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
542 lines
13 KiB
C
542 lines
13 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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* (C) 2006-2012 Patrick McHardy <kaber@trash.net>
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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/slab.h>
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#include <linux/mutex.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/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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static struct nf_conntrack_l4proto __rcu **nf_ct_protos[NFPROTO_NUMPROTO] __read_mostly;
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struct nf_conntrack_l3proto __rcu *nf_ct_l3protos[NFPROTO_NUMPROTO] __read_mostly;
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EXPORT_SYMBOL_GPL(nf_ct_l3protos);
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static DEFINE_MUTEX(nf_ct_proto_mutex);
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#ifdef CONFIG_SYSCTL
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static int
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nf_ct_register_sysctl(struct net *net,
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struct ctl_table_header **header,
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const char *path,
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struct ctl_table *table)
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{
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if (*header == NULL) {
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*header = register_net_sysctl(net, path, table);
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if (*header == NULL)
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return -ENOMEM;
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}
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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,
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unsigned int users)
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{
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if (users > 0)
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return;
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unregister_net_sysctl_table(*header);
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kfree(*table);
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*header = NULL;
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*table = 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 >= NFPROTO_NUMPROTO || nf_ct_protos[l3proto] == NULL))
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return &nf_conntrack_l4proto_generic;
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return rcu_dereference(nf_ct_protos[l3proto][l4proto]);
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}
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EXPORT_SYMBOL_GPL(__nf_ct_l4proto_find);
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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_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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rcu_read_lock();
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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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rcu_read_unlock();
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return p;
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}
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EXPORT_SYMBOL_GPL(nf_ct_l3proto_find_get);
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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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EXPORT_SYMBOL_GPL(nf_ct_l3proto_try_module_get);
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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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/* rcu_read_lock not necessary since the caller holds a reference, but
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* taken anyways to avoid lockdep warnings in __nf_ct_l3proto_find()
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*/
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rcu_read_lock();
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p = __nf_ct_l3proto_find(l3proto);
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module_put(p->me);
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rcu_read_unlock();
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}
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EXPORT_SYMBOL_GPL(nf_ct_l3proto_module_put);
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int nf_ct_netns_get(struct net *net, u8 nfproto)
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{
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const struct nf_conntrack_l3proto *l3proto;
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int ret;
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might_sleep();
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ret = nf_ct_l3proto_try_module_get(nfproto);
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if (ret < 0)
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return ret;
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/* we already have a reference, can't fail */
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rcu_read_lock();
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l3proto = __nf_ct_l3proto_find(nfproto);
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rcu_read_unlock();
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if (!l3proto->net_ns_get)
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return 0;
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ret = l3proto->net_ns_get(net);
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if (ret < 0)
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nf_ct_l3proto_module_put(nfproto);
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return ret;
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}
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EXPORT_SYMBOL_GPL(nf_ct_netns_get);
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void nf_ct_netns_put(struct net *net, u8 nfproto)
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{
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const struct nf_conntrack_l3proto *l3proto;
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might_sleep();
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/* same as nf_conntrack_netns_get(), reference assumed */
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rcu_read_lock();
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l3proto = __nf_ct_l3proto_find(nfproto);
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rcu_read_unlock();
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if (WARN_ON(!l3proto))
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return;
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if (l3proto->net_ns_put)
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l3proto->net_ns_put(net);
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nf_ct_l3proto_module_put(nfproto);
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}
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EXPORT_SYMBOL_GPL(nf_ct_netns_put);
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struct nf_conntrack_l4proto *
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nf_ct_l4proto_find_get(u_int16_t l3num, u_int8_t l4num)
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{
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struct nf_conntrack_l4proto *p;
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rcu_read_lock();
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p = __nf_ct_l4proto_find(l3num, l4num);
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if (!try_module_get(p->me))
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p = &nf_conntrack_l4proto_generic;
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rcu_read_unlock();
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return p;
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}
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EXPORT_SYMBOL_GPL(nf_ct_l4proto_find_get);
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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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EXPORT_SYMBOL_GPL(nf_ct_l4proto_put);
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static int kill_l3proto(struct nf_conn *i, void *data)
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{
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return nf_ct_l3num(i) == ((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 = data;
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return nf_ct_protonum(i) == l4proto->l4proto &&
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nf_ct_l3num(i) == l4proto->l3proto;
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}
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int nf_ct_l3proto_register(struct nf_conntrack_l3proto *proto)
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{
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int ret = 0;
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struct nf_conntrack_l3proto *old;
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if (proto->l3proto >= NFPROTO_NUMPROTO)
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return -EBUSY;
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if (proto->tuple_to_nlattr && !proto->nlattr_tuple_size)
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return -EINVAL;
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mutex_lock(&nf_ct_proto_mutex);
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old = rcu_dereference_protected(nf_ct_l3protos[proto->l3proto],
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lockdep_is_held(&nf_ct_proto_mutex));
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if (old != &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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if (proto->nlattr_tuple_size)
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proto->nla_size = 3 * proto->nlattr_tuple_size();
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rcu_assign_pointer(nf_ct_l3protos[proto->l3proto], proto);
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out_unlock:
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mutex_unlock(&nf_ct_proto_mutex);
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return ret;
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}
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EXPORT_SYMBOL_GPL(nf_ct_l3proto_register);
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void nf_ct_l3proto_unregister(struct nf_conntrack_l3proto *proto)
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{
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BUG_ON(proto->l3proto >= NFPROTO_NUMPROTO);
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mutex_lock(&nf_ct_proto_mutex);
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BUG_ON(rcu_dereference_protected(nf_ct_l3protos[proto->l3proto],
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lockdep_is_held(&nf_ct_proto_mutex)
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) != proto);
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rcu_assign_pointer(nf_ct_l3protos[proto->l3proto],
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&nf_conntrack_l3proto_generic);
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mutex_unlock(&nf_ct_proto_mutex);
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synchronize_rcu();
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/* Remove all contrack entries for this protocol */
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nf_ct_iterate_destroy(kill_l3proto, proto);
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}
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EXPORT_SYMBOL_GPL(nf_ct_l3proto_unregister);
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static struct nf_proto_net *nf_ct_l4proto_net(struct net *net,
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struct nf_conntrack_l4proto *l4proto)
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{
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if (l4proto->get_net_proto) {
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/* statically built-in protocols use static per-net */
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return l4proto->get_net_proto(net);
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} else if (l4proto->net_id) {
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/* ... and loadable protocols use dynamic per-net */
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return net_generic(net, *l4proto->net_id);
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}
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return NULL;
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}
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static
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int nf_ct_l4proto_register_sysctl(struct net *net,
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struct nf_proto_net *pn,
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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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if (pn->ctl_table != NULL) {
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err = nf_ct_register_sysctl(net,
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&pn->ctl_table_header,
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"net/netfilter",
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pn->ctl_table);
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if (err < 0) {
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if (!pn->users) {
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kfree(pn->ctl_table);
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pn->ctl_table = NULL;
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}
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}
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}
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#endif /* CONFIG_SYSCTL */
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return err;
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}
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static
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void nf_ct_l4proto_unregister_sysctl(struct net *net,
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struct nf_proto_net *pn,
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struct nf_conntrack_l4proto *l4proto)
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{
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#ifdef CONFIG_SYSCTL
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if (pn->ctl_table_header != NULL)
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nf_ct_unregister_sysctl(&pn->ctl_table_header,
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&pn->ctl_table,
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pn->users);
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#endif /* CONFIG_SYSCTL */
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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_ct_l4proto_register_one(struct nf_conntrack_l4proto *l4proto)
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{
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int ret = 0;
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if (l4proto->l3proto >= ARRAY_SIZE(nf_ct_protos))
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return -EBUSY;
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if ((l4proto->to_nlattr && !l4proto->nlattr_size) ||
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(l4proto->tuple_to_nlattr && !l4proto->nlattr_tuple_size))
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return -EINVAL;
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mutex_lock(&nf_ct_proto_mutex);
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if (!nf_ct_protos[l4proto->l3proto]) {
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/* l3proto may be loaded latter. */
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struct nf_conntrack_l4proto __rcu **proto_array;
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int i;
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proto_array = 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_unlock;
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}
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for (i = 0; i < MAX_NF_CT_PROTO; i++)
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RCU_INIT_POINTER(proto_array[i],
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&nf_conntrack_l4proto_generic);
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/* Before making proto_array visible to lockless readers,
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* we must make sure its content is committed to memory.
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*/
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smp_wmb();
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nf_ct_protos[l4proto->l3proto] = proto_array;
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} else if (rcu_dereference_protected(
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nf_ct_protos[l4proto->l3proto][l4proto->l4proto],
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lockdep_is_held(&nf_ct_proto_mutex)
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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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l4proto->nla_size = 0;
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if (l4proto->nlattr_size)
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l4proto->nla_size += l4proto->nlattr_size();
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if (l4proto->nlattr_tuple_size)
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l4proto->nla_size += 3 * l4proto->nlattr_tuple_size();
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rcu_assign_pointer(nf_ct_protos[l4proto->l3proto][l4proto->l4proto],
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l4proto);
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out_unlock:
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mutex_unlock(&nf_ct_proto_mutex);
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return ret;
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}
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EXPORT_SYMBOL_GPL(nf_ct_l4proto_register_one);
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int nf_ct_l4proto_pernet_register_one(struct net *net,
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struct nf_conntrack_l4proto *l4proto)
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{
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int ret = 0;
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struct nf_proto_net *pn = NULL;
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if (l4proto->init_net) {
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ret = l4proto->init_net(net, l4proto->l3proto);
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if (ret < 0)
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goto out;
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}
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pn = nf_ct_l4proto_net(net, l4proto);
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if (pn == NULL)
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goto out;
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ret = nf_ct_l4proto_register_sysctl(net, pn, l4proto);
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if (ret < 0)
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goto out;
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pn->users++;
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out:
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return ret;
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}
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EXPORT_SYMBOL_GPL(nf_ct_l4proto_pernet_register_one);
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static void __nf_ct_l4proto_unregister_one(struct nf_conntrack_l4proto *l4proto)
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{
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BUG_ON(l4proto->l3proto >= ARRAY_SIZE(nf_ct_protos));
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BUG_ON(rcu_dereference_protected(
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nf_ct_protos[l4proto->l3proto][l4proto->l4proto],
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lockdep_is_held(&nf_ct_proto_mutex)
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) != l4proto);
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rcu_assign_pointer(nf_ct_protos[l4proto->l3proto][l4proto->l4proto],
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&nf_conntrack_l4proto_generic);
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}
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void nf_ct_l4proto_unregister_one(struct nf_conntrack_l4proto *l4proto)
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{
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mutex_lock(&nf_ct_proto_mutex);
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__nf_ct_l4proto_unregister_one(l4proto);
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mutex_unlock(&nf_ct_proto_mutex);
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synchronize_rcu();
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}
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EXPORT_SYMBOL_GPL(nf_ct_l4proto_unregister_one);
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void nf_ct_l4proto_pernet_unregister_one(struct net *net,
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struct nf_conntrack_l4proto *l4proto)
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{
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struct nf_proto_net *pn = nf_ct_l4proto_net(net, l4proto);
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if (pn == NULL)
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return;
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pn->users--;
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nf_ct_l4proto_unregister_sysctl(net, pn, l4proto);
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}
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EXPORT_SYMBOL_GPL(nf_ct_l4proto_pernet_unregister_one);
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int nf_ct_l4proto_register(struct nf_conntrack_l4proto *l4proto[],
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unsigned int num_proto)
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{
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int ret = -EINVAL, ver;
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unsigned int i;
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for (i = 0; i < num_proto; i++) {
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ret = nf_ct_l4proto_register_one(l4proto[i]);
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if (ret < 0)
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break;
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}
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if (i != num_proto) {
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ver = l4proto[i]->l3proto == PF_INET6 ? 6 : 4;
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pr_err("nf_conntrack_ipv%d: can't register %s%d proto.\n",
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ver, l4proto[i]->name, ver);
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nf_ct_l4proto_unregister(l4proto, i);
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}
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return ret;
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}
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EXPORT_SYMBOL_GPL(nf_ct_l4proto_register);
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int nf_ct_l4proto_pernet_register(struct net *net,
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struct nf_conntrack_l4proto *l4proto[],
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unsigned int num_proto)
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{
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int ret = -EINVAL;
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unsigned int i;
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for (i = 0; i < num_proto; i++) {
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ret = nf_ct_l4proto_pernet_register_one(net, l4proto[i]);
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if (ret < 0)
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break;
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}
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if (i != num_proto) {
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pr_err("nf_conntrack_%s%d: pernet registration failed\n",
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l4proto[i]->name,
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l4proto[i]->l3proto == PF_INET6 ? 6 : 4);
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nf_ct_l4proto_pernet_unregister(net, l4proto, i);
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}
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return ret;
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}
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EXPORT_SYMBOL_GPL(nf_ct_l4proto_pernet_register);
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void nf_ct_l4proto_unregister(struct nf_conntrack_l4proto *l4proto[],
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unsigned int num_proto)
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{
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mutex_lock(&nf_ct_proto_mutex);
|
|
while (num_proto-- != 0)
|
|
__nf_ct_l4proto_unregister_one(l4proto[num_proto]);
|
|
mutex_unlock(&nf_ct_proto_mutex);
|
|
|
|
synchronize_net();
|
|
/* Remove all contrack entries for this protocol */
|
|
nf_ct_iterate_destroy(kill_l4proto, l4proto);
|
|
}
|
|
EXPORT_SYMBOL_GPL(nf_ct_l4proto_unregister);
|
|
|
|
void nf_ct_l4proto_pernet_unregister(struct net *net,
|
|
struct nf_conntrack_l4proto *l4proto[],
|
|
unsigned int num_proto)
|
|
{
|
|
while (num_proto-- != 0)
|
|
nf_ct_l4proto_pernet_unregister_one(net, l4proto[num_proto]);
|
|
}
|
|
EXPORT_SYMBOL_GPL(nf_ct_l4proto_pernet_unregister);
|
|
|
|
int nf_conntrack_proto_pernet_init(struct net *net)
|
|
{
|
|
int err;
|
|
struct nf_proto_net *pn = nf_ct_l4proto_net(net,
|
|
&nf_conntrack_l4proto_generic);
|
|
|
|
err = nf_conntrack_l4proto_generic.init_net(net,
|
|
nf_conntrack_l4proto_generic.l3proto);
|
|
if (err < 0)
|
|
return err;
|
|
err = nf_ct_l4proto_register_sysctl(net,
|
|
pn,
|
|
&nf_conntrack_l4proto_generic);
|
|
if (err < 0)
|
|
return err;
|
|
|
|
pn->users++;
|
|
return 0;
|
|
}
|
|
|
|
void nf_conntrack_proto_pernet_fini(struct net *net)
|
|
{
|
|
struct nf_proto_net *pn = nf_ct_l4proto_net(net,
|
|
&nf_conntrack_l4proto_generic);
|
|
|
|
pn->users--;
|
|
nf_ct_l4proto_unregister_sysctl(net,
|
|
pn,
|
|
&nf_conntrack_l4proto_generic);
|
|
}
|
|
|
|
int nf_conntrack_proto_init(void)
|
|
{
|
|
unsigned int i;
|
|
for (i = 0; i < NFPROTO_NUMPROTO; i++)
|
|
rcu_assign_pointer(nf_ct_l3protos[i],
|
|
&nf_conntrack_l3proto_generic);
|
|
return 0;
|
|
}
|
|
|
|
void nf_conntrack_proto_fini(void)
|
|
{
|
|
unsigned int i;
|
|
/* free l3proto protocol tables */
|
|
for (i = 0; i < ARRAY_SIZE(nf_ct_protos); i++)
|
|
kfree(nf_ct_protos[i]);
|
|
}
|