commit 549db1232fad40206a2ab6e334f0a4359602be5e Author: Patrick McHardy Date: Tue Jan 19 09:57:14 2010 +0100 netfilter: xtables: add CT target Add a new target for the raw table, which can be used to specify conntrack parameters for specific connections, f.i. the conntrack helper. The target attaches a "template" connection tracking entry to the skb, which is used by the conntrack core when initializing the new conntrack. Signed-off-by: Patrick McHardy diff --git a/include/linux/netfilter/nf_conntrack_common.h b/include/linux/netfilter/nf_conntrack_common.h index a374787..75f3150 100644 --- a/include/linux/netfilter/nf_conntrack_common.h +++ b/include/linux/netfilter/nf_conntrack_common.h @@ -72,6 +72,10 @@ enum ip_conntrack_status { /* Connection has fixed timeout. */ IPS_FIXED_TIMEOUT_BIT = 10, IPS_FIXED_TIMEOUT = (1 << IPS_FIXED_TIMEOUT_BIT), + + /* Conntrack is a template */ + IPS_TEMPLATE_BIT = 11, + IPS_TEMPLATE = (1 << IPS_TEMPLATE_BIT), }; #ifdef __KERNEL__ diff --git a/include/linux/netfilter/xt_CT.h b/include/linux/netfilter/xt_CT.h new file mode 100644 index 0000000..70c3239 --- /dev/null +++ b/include/linux/netfilter/xt_CT.h @@ -0,0 +1,11 @@ +#ifndef _XT_CT_H +#define _XT_CT_H + +struct xt_ct_target_info { + char helper[16]; + + /* Used internally by the kernel */ + struct nf_conn *ct __attribute__((aligned(8))); +}; + +#endif /* _XT_CT_H */ diff --git a/include/net/netfilter/nf_conntrack_helper.h b/include/net/netfilter/nf_conntrack_helper.h index d015de9..61cbc6d 100644 --- a/include/net/netfilter/nf_conntrack_helper.h +++ b/include/net/netfilter/nf_conntrack_helper.h @@ -42,12 +42,16 @@ struct nf_conntrack_helper { extern struct nf_conntrack_helper * __nf_conntrack_helper_find_byname(const char *name); +extern struct nf_conntrack_helper * +nf_conntrack_helper_try_module_get(const char *name); + extern int nf_conntrack_helper_register(struct nf_conntrack_helper *); extern void nf_conntrack_helper_unregister(struct nf_conntrack_helper *); extern struct nf_conn_help *nf_ct_helper_ext_add(struct nf_conn *ct, gfp_t gfp); -extern int __nf_ct_try_assign_helper(struct nf_conn *ct, gfp_t flags); +extern int __nf_ct_try_assign_helper(struct nf_conn *ct, struct nf_conn *tmpl, + gfp_t flags); extern void nf_ct_helper_destroy(struct nf_conn *ct); diff --git a/net/netfilter/Kconfig b/net/netfilter/Kconfig index 634d14a..2cd1415 100644 --- a/net/netfilter/Kconfig +++ b/net/netfilter/Kconfig @@ -341,6 +341,11 @@ config NETFILTER_XT_TARGET_CONNSECMARK To compile it as a module, choose M here. If unsure, say N. +config NETFILTER_XT_TARGET_CT + tristate '"CT" target support' + depends on NF_CONNTRACK + depends on NETFILTER_ADVANCED + config NETFILTER_XT_TARGET_DSCP tristate '"DSCP" and "TOS" target support' depends on IP_NF_MANGLE || IP6_NF_MANGLE diff --git a/net/netfilter/Makefile b/net/netfilter/Makefile index 49f62ee..f873644 100644 --- a/net/netfilter/Makefile +++ b/net/netfilter/Makefile @@ -44,6 +44,7 @@ obj-$(CONFIG_NETFILTER_XTABLES) += x_tables.o xt_tcpudp.o obj-$(CONFIG_NETFILTER_XT_TARGET_CLASSIFY) += xt_CLASSIFY.o obj-$(CONFIG_NETFILTER_XT_TARGET_CONNMARK) += xt_CONNMARK.o obj-$(CONFIG_NETFILTER_XT_TARGET_CONNSECMARK) += xt_CONNSECMARK.o +obj-$(CONFIG_NETFILTER_XT_TARGET_CT) += xt_CT.o obj-$(CONFIG_NETFILTER_XT_TARGET_DSCP) += xt_DSCP.o obj-$(CONFIG_NETFILTER_XT_TARGET_HL) += xt_HL.o obj-$(CONFIG_NETFILTER_XT_TARGET_LED) += xt_LED.o diff --git a/net/netfilter/nf_conntrack_core.c b/net/netfilter/nf_conntrack_core.c index 0e98c32..08a7c60 100644 --- a/net/netfilter/nf_conntrack_core.c +++ b/net/netfilter/nf_conntrack_core.c @@ -618,7 +618,7 @@ EXPORT_SYMBOL_GPL(nf_conntrack_free); /* Allocate a new conntrack: we return -ENOMEM if classification failed due to stress. Otherwise it really is unclassifiable. */ static struct nf_conntrack_tuple_hash * -init_conntrack(struct net *net, +init_conntrack(struct net *net, struct nf_conn *tmpl, const struct nf_conntrack_tuple *tuple, struct nf_conntrack_l3proto *l3proto, struct nf_conntrack_l4proto *l4proto, @@ -673,7 +673,7 @@ init_conntrack(struct net *net, nf_conntrack_get(&ct->master->ct_general); NF_CT_STAT_INC(net, expect_new); } else { - __nf_ct_try_assign_helper(ct, GFP_ATOMIC); + __nf_ct_try_assign_helper(ct, tmpl, GFP_ATOMIC); NF_CT_STAT_INC(net, new); } @@ -694,7 +694,7 @@ init_conntrack(struct net *net, /* On success, returns conntrack ptr, sets skb->nfct and ctinfo */ static inline struct nf_conn * -resolve_normal_ct(struct net *net, +resolve_normal_ct(struct net *net, struct nf_conn *tmpl, struct sk_buff *skb, unsigned int dataoff, u_int16_t l3num, @@ -718,7 +718,8 @@ resolve_normal_ct(struct net *net, /* look for tuple match */ h = nf_conntrack_find_get(net, &tuple); if (!h) { - h = init_conntrack(net, &tuple, l3proto, l4proto, skb, dataoff); + h = init_conntrack(net, tmpl, &tuple, l3proto, l4proto, + skb, dataoff); if (!h) return NULL; if (IS_ERR(h)) @@ -755,7 +756,7 @@ unsigned int nf_conntrack_in(struct net *net, u_int8_t pf, unsigned int hooknum, struct sk_buff *skb) { - struct nf_conn *ct; + struct nf_conn *ct, *tmpl = NULL; enum ip_conntrack_info ctinfo; struct nf_conntrack_l3proto *l3proto; struct nf_conntrack_l4proto *l4proto; @@ -764,10 +765,14 @@ nf_conntrack_in(struct net *net, u_int8_t pf, unsigned int hooknum, int set_reply = 0; int ret; - /* Previously seen (loopback or untracked)? Ignore. */ if (skb->nfct) { - NF_CT_STAT_INC_ATOMIC(net, ignore); - return NF_ACCEPT; + /* Previously seen (loopback or untracked)? Ignore. */ + tmpl = (struct nf_conn *)skb->nfct; + if (!test_bit(IPS_TEMPLATE_BIT, &tmpl->status)) { + NF_CT_STAT_INC_ATOMIC(net, ignore); + return NF_ACCEPT; + } + skb->nfct = NULL; } /* rcu_read_lock()ed by nf_hook_slow */ @@ -778,7 +783,8 @@ nf_conntrack_in(struct net *net, u_int8_t pf, unsigned int hooknum, pr_debug("not prepared to track yet or error occured\n"); NF_CT_STAT_INC_ATOMIC(net, error); NF_CT_STAT_INC_ATOMIC(net, invalid); - return -ret; + ret = -ret; + goto out; } l4proto = __nf_ct_l4proto_find(pf, protonum); @@ -791,22 +797,25 @@ nf_conntrack_in(struct net *net, u_int8_t pf, unsigned int hooknum, if (ret <= 0) { NF_CT_STAT_INC_ATOMIC(net, error); NF_CT_STAT_INC_ATOMIC(net, invalid); - return -ret; + ret = -ret; + goto out; } } - ct = resolve_normal_ct(net, skb, dataoff, pf, protonum, + ct = resolve_normal_ct(net, tmpl, skb, dataoff, pf, protonum, l3proto, l4proto, &set_reply, &ctinfo); if (!ct) { /* Not valid part of a connection */ NF_CT_STAT_INC_ATOMIC(net, invalid); - return NF_ACCEPT; + ret = NF_ACCEPT; + goto out; } if (IS_ERR(ct)) { /* Too stressed to deal. */ NF_CT_STAT_INC_ATOMIC(net, drop); - return NF_DROP; + ret = NF_DROP; + goto out; } NF_CT_ASSERT(skb->nfct); @@ -821,11 +830,15 @@ nf_conntrack_in(struct net *net, u_int8_t pf, unsigned int hooknum, NF_CT_STAT_INC_ATOMIC(net, invalid); if (ret == -NF_DROP) NF_CT_STAT_INC_ATOMIC(net, drop); - return -ret; + ret = -ret; + goto out; } if (set_reply && !test_and_set_bit(IPS_SEEN_REPLY_BIT, &ct->status)) nf_conntrack_event_cache(IPCT_STATUS, ct); +out: + if (tmpl) + nf_ct_put(tmpl); return ret; } @@ -864,7 +877,7 @@ void nf_conntrack_alter_reply(struct nf_conn *ct, return; rcu_read_lock(); - __nf_ct_try_assign_helper(ct, GFP_ATOMIC); + __nf_ct_try_assign_helper(ct, NULL, GFP_ATOMIC); rcu_read_unlock(); } EXPORT_SYMBOL_GPL(nf_conntrack_alter_reply); diff --git a/net/netfilter/nf_conntrack_helper.c b/net/netfilter/nf_conntrack_helper.c index 65c2a7b..0424a64 100644 --- a/net/netfilter/nf_conntrack_helper.c +++ b/net/netfilter/nf_conntrack_helper.c @@ -81,6 +81,25 @@ __nf_conntrack_helper_find_byname(const char *name) } EXPORT_SYMBOL_GPL(__nf_conntrack_helper_find_byname); +struct nf_conntrack_helper * +nf_conntrack_helper_try_module_get(const char *name) +{ + struct nf_conntrack_helper *h; + + h = __nf_conntrack_helper_find_byname(name); +#ifdef CONFIG_MODULES + if (h == NULL) { + if (request_module("nfct-helper-%s", name) == 0) + h = __nf_conntrack_helper_find_byname(name); + } +#endif + if (h != NULL && !try_module_get(h->me)) + h = NULL; + + return h; +} +EXPORT_SYMBOL_GPL(nf_conntrack_helper_try_module_get); + struct nf_conn_help *nf_ct_helper_ext_add(struct nf_conn *ct, gfp_t gfp) { struct nf_conn_help *help; @@ -94,13 +113,22 @@ struct nf_conn_help *nf_ct_helper_ext_add(struct nf_conn *ct, gfp_t gfp) } EXPORT_SYMBOL_GPL(nf_ct_helper_ext_add); -int __nf_ct_try_assign_helper(struct nf_conn *ct, gfp_t flags) +int __nf_ct_try_assign_helper(struct nf_conn *ct, struct nf_conn *tmpl, + gfp_t flags) { + struct nf_conntrack_helper *helper = NULL; + struct nf_conn_help *help; int ret = 0; - struct nf_conntrack_helper *helper; - struct nf_conn_help *help = nfct_help(ct); - helper = __nf_ct_helper_find(&ct->tuplehash[IP_CT_DIR_REPLY].tuple); + if (tmpl != NULL) { + help = nfct_help(tmpl); + if (help != NULL) + helper = help->helper; + } + + help = nfct_help(ct); + if (helper == NULL) + helper = __nf_ct_helper_find(&ct->tuplehash[IP_CT_DIR_REPLY].tuple); if (helper == NULL) { if (help) rcu_assign_pointer(help->helper, NULL); diff --git a/net/netfilter/nf_conntrack_netlink.c b/net/netfilter/nf_conntrack_netlink.c index 79478df..8bc57c9 100644 --- a/net/netfilter/nf_conntrack_netlink.c +++ b/net/netfilter/nf_conntrack_netlink.c @@ -1244,7 +1244,7 @@ ctnetlink_create_conntrack(struct net *net, } } else { /* try an implicit helper assignation */ - err = __nf_ct_try_assign_helper(ct, GFP_ATOMIC); + err = __nf_ct_try_assign_helper(ct, NULL, GFP_ATOMIC); if (err < 0) goto err2; } diff --git a/net/netfilter/xt_CT.c b/net/netfilter/xt_CT.c new file mode 100644 index 0000000..115b23d --- /dev/null +++ b/net/netfilter/xt_CT.c @@ -0,0 +1,110 @@ +/* + * Copyright (c) 2010 Patrick McHardy + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License version 2 as + * published by the Free Software Foundation. + */ + +#include +#include +#include +#include +#include +#include +#include + +static unsigned int xt_ct_target(struct sk_buff *skb, + const struct xt_target_param *par) +{ + const struct xt_ct_target_info *info = par->targinfo; + struct nf_conn *ct = info->ct; + + atomic_inc(&ct->ct_general.use); + skb->nfct = &ct->ct_general; + skb->nfctinfo = IP_CT_NEW; + + return XT_CONTINUE; +} + +static bool xt_ct_tg_check(const struct xt_tgchk_param *par) +{ + struct xt_ct_target_info *info = par->targinfo; + struct nf_conntrack_tuple t; + struct nf_conn_help *help; + struct nf_conn *ct; + + if (nf_ct_l3proto_try_module_get(par->family) < 0) + goto err1; + + memset(&t, 0, sizeof(t)); + ct = nf_conntrack_alloc(par->net, &t, &t, GFP_KERNEL); + if (IS_ERR(ct)) + goto err2; + + if (info->helper[0]) { + help = nf_ct_helper_ext_add(ct, GFP_KERNEL); + if (help == NULL) + goto err3; + + help->helper = nf_conntrack_helper_try_module_get(info->helper); + if (help->helper == NULL) + goto err3; + } + + __set_bit(IPS_TEMPLATE_BIT, &ct->status); + __set_bit(IPS_CONFIRMED_BIT, &ct->status); + + info->ct = ct; + return true; + +err3: + nf_conntrack_free(ct); +err2: + nf_ct_l3proto_module_put(par->family); +err1: + return false; +} + +static void xt_ct_tg_destroy(const struct xt_tgdtor_param *par) +{ + struct xt_ct_target_info *info = par->targinfo; + struct nf_conn *ct = info->ct; + struct nf_conn_help *help; + + help = nfct_help(ct); + if (help) + module_put(help->helper->me); + + nf_ct_l3proto_module_put(par->family); + nf_ct_put(info->ct); +} + +static struct xt_target xt_ct_tg __read_mostly = { + .name = "CT", + .family = NFPROTO_UNSPEC, + .targetsize = XT_ALIGN(sizeof(struct xt_ct_target_info)), + .checkentry = xt_ct_tg_check, + .destroy = xt_ct_tg_destroy, + .target = xt_ct_target, + .table = "raw", + .me = THIS_MODULE, +}; + +static int __init xt_ct_tg_init(void) +{ + return xt_register_target(&xt_ct_tg); +} + +static void __exit xt_ct_tg_exit(void) +{ + return xt_unregister_target(&xt_ct_tg); +} + +module_init(xt_ct_tg_init); +module_exit(xt_ct_tg_exit); + +MODULE_LICENSE("GPL"); +MODULE_DESCRIPTION("Xtables: connection tracking target"); +MODULE_ALIAS("ipt_CT"); +MODULE_ALIAS("ip6t_CT");