From 24de58f465165298aaa8f286b2592f0163706cfe Mon Sep 17 00:00:00 2001 From: Pablo Neira Ayuso Date: Wed, 29 Feb 2012 02:19:19 +0100 Subject: [PATCH] netfilter: xt_CT: allow to attach timeout policy + glue code This patch allows you to attach the timeout policy via the CT target, it adds a new revision of the target to ensure backward compatibility. Moreover, it also contains the glue code to stick the timeout object defined via nfnetlink_cttimeout to the given flow. Example usage (it requires installing the nfct tool and libnetfilter_cttimeout): 1) create the timeout policy: nfct timeout add tcp-policy0 inet tcp \ established 1000 close 10 time_wait 10 last_ack 10 2) attach the timeout policy to the packet: iptables -I PREROUTING -t raw -p tcp -j CT --timeout tcp-policy0 You have to install the following user-space software: a) libnetfilter_cttimeout: git://git.netfilter.org/libnetfilter_cttimeout b) nfct: git://git.netfilter.org/nfct You also have to get iptables with -j CT --timeout support. Signed-off-by: Pablo Neira Ayuso --- include/linux/netfilter/xt_CT.h | 12 ++ net/netfilter/nf_conntrack_core.c | 11 +- net/netfilter/nfnetlink_cttimeout.c | 41 ++++++ net/netfilter/xt_CT.c | 220 ++++++++++++++++++++++++++-- 4 files changed, 268 insertions(+), 16 deletions(-) diff --git a/include/linux/netfilter/xt_CT.h b/include/linux/netfilter/xt_CT.h index b56e76811c04..a064b8af360c 100644 --- a/include/linux/netfilter/xt_CT.h +++ b/include/linux/netfilter/xt_CT.h @@ -16,4 +16,16 @@ struct xt_ct_target_info { struct nf_conn *ct __attribute__((aligned(8))); }; +struct xt_ct_target_info_v1 { + __u16 flags; + __u16 zone; + __u32 ct_events; + __u32 exp_events; + char helper[16]; + char timeout[32]; + + /* Used internally by the kernel */ + struct nf_conn *ct __attribute__((aligned(8))); +}; + #endif /* _XT_CT_H */ diff --git a/net/netfilter/nf_conntrack_core.c b/net/netfilter/nf_conntrack_core.c index 75398c535719..81e2aa4ca1fe 100644 --- a/net/netfilter/nf_conntrack_core.c +++ b/net/netfilter/nf_conntrack_core.c @@ -912,6 +912,7 @@ nf_conntrack_in(struct net *net, u_int8_t pf, unsigned int hooknum, enum ip_conntrack_info ctinfo; struct nf_conntrack_l3proto *l3proto; struct nf_conntrack_l4proto *l4proto; + struct nf_conn_timeout *timeout_ext; unsigned int *timeouts; unsigned int dataoff; u_int8_t protonum; @@ -959,7 +960,15 @@ nf_conntrack_in(struct net *net, u_int8_t pf, unsigned int hooknum, goto out; } - timeouts = l4proto->get_timeouts(net); + /* Decide what timeout policy we want to apply to this flow. */ + if (tmpl) { + timeout_ext = nf_ct_timeout_find(tmpl); + if (timeout_ext) + timeouts = NF_CT_TIMEOUT_EXT_DATA(timeout_ext); + else + timeouts = l4proto->get_timeouts(net); + } else + timeouts = l4proto->get_timeouts(net); ct = resolve_normal_ct(net, tmpl, skb, dataoff, pf, protonum, l3proto, l4proto, &set_reply, &ctinfo, diff --git a/net/netfilter/nfnetlink_cttimeout.c b/net/netfilter/nfnetlink_cttimeout.c index 29b989715162..fec29a43de4d 100644 --- a/net/netfilter/nfnetlink_cttimeout.c +++ b/net/netfilter/nfnetlink_cttimeout.c @@ -29,6 +29,7 @@ #include #include #include +#include #include #include @@ -331,6 +332,38 @@ cttimeout_del_timeout(struct sock *ctnl, struct sk_buff *skb, return ret; } +#ifdef CONFIG_NF_CONNTRACK_TIMEOUT +static struct ctnl_timeout *ctnl_timeout_find_get(const char *name) +{ + struct ctnl_timeout *timeout, *matching = NULL; + + rcu_read_lock(); + list_for_each_entry_rcu(timeout, &cttimeout_list, head) { + if (strncmp(timeout->name, name, CTNL_TIMEOUT_NAME_MAX) != 0) + continue; + + if (!try_module_get(THIS_MODULE)) + goto err; + + if (!atomic_inc_not_zero(&timeout->refcnt)) { + module_put(THIS_MODULE); + goto err; + } + matching = timeout; + break; + } +err: + rcu_read_unlock(); + return matching; +} + +static void ctnl_timeout_put(struct ctnl_timeout *timeout) +{ + atomic_dec(&timeout->refcnt); + module_put(THIS_MODULE); +} +#endif /* CONFIG_NF_CONNTRACK_TIMEOUT */ + static const struct nfnl_callback cttimeout_cb[IPCTNL_MSG_TIMEOUT_MAX] = { [IPCTNL_MSG_TIMEOUT_NEW] = { .call = cttimeout_new_timeout, .attr_count = CTA_TIMEOUT_MAX, @@ -362,6 +395,10 @@ static int __init cttimeout_init(void) "nfnetlink.\n"); goto err_out; } +#ifdef CONFIG_NF_CONNTRACK_TIMEOUT + RCU_INIT_POINTER(nf_ct_timeout_find_get_hook, ctnl_timeout_find_get); + RCU_INIT_POINTER(nf_ct_timeout_put_hook, ctnl_timeout_put); +#endif /* CONFIG_NF_CONNTRACK_TIMEOUT */ return 0; err_out: @@ -382,6 +419,10 @@ static void __exit cttimeout_exit(void) */ kfree_rcu(cur, rcu_head); } +#ifdef CONFIG_NF_CONNTRACK_TIMEOUT + RCU_INIT_POINTER(nf_ct_timeout_find_get_hook, NULL); + RCU_INIT_POINTER(nf_ct_timeout_put_hook, NULL); +#endif /* CONFIG_NF_CONNTRACK_TIMEOUT */ } module_init(cttimeout_init); diff --git a/net/netfilter/xt_CT.c b/net/netfilter/xt_CT.c index 0221d10de75a..b873445df444 100644 --- a/net/netfilter/xt_CT.c +++ b/net/netfilter/xt_CT.c @@ -16,10 +16,11 @@ #include #include #include +#include #include -static unsigned int xt_ct_target(struct sk_buff *skb, - const struct xt_action_param *par) +static unsigned int xt_ct_target_v0(struct sk_buff *skb, + const struct xt_action_param *par) { const struct xt_ct_target_info *info = par->targinfo; struct nf_conn *ct = info->ct; @@ -35,6 +36,23 @@ static unsigned int xt_ct_target(struct sk_buff *skb, return XT_CONTINUE; } +static unsigned int xt_ct_target_v1(struct sk_buff *skb, + const struct xt_action_param *par) +{ + const struct xt_ct_target_info_v1 *info = par->targinfo; + struct nf_conn *ct = info->ct; + + /* Previously seen (loopback)? Ignore. */ + if (skb->nfct != NULL) + return XT_CONTINUE; + + atomic_inc(&ct->ct_general.use); + skb->nfct = &ct->ct_general; + skb->nfctinfo = IP_CT_NEW; + + return XT_CONTINUE; +} + static u8 xt_ct_find_proto(const struct xt_tgchk_param *par) { if (par->family == NFPROTO_IPV4) { @@ -53,7 +71,7 @@ static u8 xt_ct_find_proto(const struct xt_tgchk_param *par) return 0; } -static int xt_ct_tg_check(const struct xt_tgchk_param *par) +static int xt_ct_tg_check_v0(const struct xt_tgchk_param *par) { struct xt_ct_target_info *info = par->targinfo; struct nf_conntrack_tuple t; @@ -130,7 +148,137 @@ err1: return ret; } -static void xt_ct_tg_destroy(const struct xt_tgdtor_param *par) +static int xt_ct_tg_check_v1(const struct xt_tgchk_param *par) +{ + struct xt_ct_target_info_v1 *info = par->targinfo; + struct nf_conntrack_tuple t; + struct nf_conn_help *help; + struct nf_conn *ct; + int ret = 0; + u8 proto; + + if (info->flags & ~XT_CT_NOTRACK) + return -EINVAL; + + if (info->flags & XT_CT_NOTRACK) { + ct = nf_ct_untracked_get(); + atomic_inc(&ct->ct_general.use); + goto out; + } + +#ifndef CONFIG_NF_CONNTRACK_ZONES + if (info->zone) + goto err1; +#endif + + ret = nf_ct_l3proto_try_module_get(par->family); + if (ret < 0) + goto err1; + + memset(&t, 0, sizeof(t)); + ct = nf_conntrack_alloc(par->net, info->zone, &t, &t, GFP_KERNEL); + ret = PTR_ERR(ct); + if (IS_ERR(ct)) + goto err2; + + ret = 0; + if ((info->ct_events || info->exp_events) && + !nf_ct_ecache_ext_add(ct, info->ct_events, info->exp_events, + GFP_KERNEL)) + goto err3; + + if (info->helper[0]) { + ret = -ENOENT; + proto = xt_ct_find_proto(par); + if (!proto) { + pr_info("You must specify a L4 protocol, " + "and not use inversions on it.\n"); + goto err3; + } + + ret = -ENOMEM; + help = nf_ct_helper_ext_add(ct, GFP_KERNEL); + if (help == NULL) + goto err3; + + ret = -ENOENT; + help->helper = nf_conntrack_helper_try_module_get(info->helper, + par->family, + proto); + if (help->helper == NULL) { + pr_info("No such helper \"%s\"\n", info->helper); + goto err3; + } + } + +#ifdef CONFIG_NF_CONNTRACK_TIMEOUT + if (info->timeout) { + typeof(nf_ct_timeout_find_get_hook) timeout_find_get; + struct ctnl_timeout *timeout; + struct nf_conn_timeout *timeout_ext; + + timeout_find_get = + rcu_dereference(nf_ct_timeout_find_get_hook); + + if (timeout_find_get) { + const struct ipt_entry *e = par->entryinfo; + + if (e->ip.invflags & IPT_INV_PROTO) { + ret = -EINVAL; + pr_info("You cannot use inversion on " + "L4 protocol\n"); + goto err3; + } + timeout = timeout_find_get(info->timeout); + if (timeout == NULL) { + ret = -ENOENT; + pr_info("No such timeout policy \"%s\"\n", + info->timeout); + goto err3; + } + if (timeout->l3num != par->family) { + ret = -EINVAL; + pr_info("Timeout policy `%s' can only be " + "used by L3 protocol number %d\n", + info->timeout, timeout->l3num); + goto err3; + } + if (timeout->l4num != e->ip.proto) { + ret = -EINVAL; + pr_info("Timeout policy `%s' can only be " + "used by L4 protocol number %d\n", + info->timeout, timeout->l4num); + goto err3; + } + timeout_ext = nf_ct_timeout_ext_add(ct, timeout, + GFP_KERNEL); + if (timeout_ext == NULL) { + ret = -ENOMEM; + goto err3; + } + } else { + ret = -ENOENT; + pr_info("Timeout policy base is empty\n"); + goto err3; + } + } +#endif + + __set_bit(IPS_TEMPLATE_BIT, &ct->status); + __set_bit(IPS_CONFIRMED_BIT, &ct->status); +out: + info->ct = ct; + return 0; + +err3: + nf_conntrack_free(ct); +err2: + nf_ct_l3proto_module_put(par->family); +err1: + return ret; +} + +static void xt_ct_tg_destroy_v0(const struct xt_tgdtor_param *par) { struct xt_ct_target_info *info = par->targinfo; struct nf_conn *ct = info->ct; @@ -146,25 +294,67 @@ static void xt_ct_tg_destroy(const struct xt_tgdtor_param *par) nf_ct_put(info->ct); } -static struct xt_target xt_ct_tg __read_mostly = { - .name = "CT", - .family = NFPROTO_UNSPEC, - .targetsize = 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 void xt_ct_tg_destroy_v1(const struct xt_tgdtor_param *par) +{ + struct xt_ct_target_info_v1 *info = par->targinfo; + struct nf_conn *ct = info->ct; + struct nf_conn_help *help; +#ifdef CONFIG_NF_CONNTRACK_TIMEOUT + struct nf_conn_timeout *timeout_ext; + typeof(nf_ct_timeout_put_hook) timeout_put; +#endif + if (!nf_ct_is_untracked(ct)) { + help = nfct_help(ct); + if (help) + module_put(help->helper->me); + + nf_ct_l3proto_module_put(par->family); + +#ifdef CONFIG_NF_CONNTRACK_TIMEOUT + timeout_put = rcu_dereference(nf_ct_timeout_put_hook); + + if (timeout_put) { + timeout_ext = nf_ct_timeout_find(ct); + if (timeout_ext) + timeout_put(timeout_ext->timeout); + } +#endif + } + nf_ct_put(info->ct); +} + +static struct xt_target xt_ct_tg_reg[] __read_mostly = { + { + .name = "CT", + .family = NFPROTO_UNSPEC, + .targetsize = sizeof(struct xt_ct_target_info), + .checkentry = xt_ct_tg_check_v0, + .destroy = xt_ct_tg_destroy_v0, + .target = xt_ct_target_v0, + .table = "raw", + .me = THIS_MODULE, + }, + { + .name = "CT", + .family = NFPROTO_UNSPEC, + .revision = 1, + .targetsize = sizeof(struct xt_ct_target_info_v1), + .checkentry = xt_ct_tg_check_v1, + .destroy = xt_ct_tg_destroy_v1, + .target = xt_ct_target_v1, + .table = "raw", + .me = THIS_MODULE, + }, }; static int __init xt_ct_tg_init(void) { - return xt_register_target(&xt_ct_tg); + return xt_register_targets(xt_ct_tg_reg, ARRAY_SIZE(xt_ct_tg_reg)); } static void __exit xt_ct_tg_exit(void) { - xt_unregister_target(&xt_ct_tg); + xt_unregister_targets(xt_ct_tg_reg, ARRAY_SIZE(xt_ct_tg_reg)); } module_init(xt_ct_tg_init); -- 2.20.1