netfilter: xt_CT: allow to attach timeout policy + glue code
authorPablo Neira Ayuso <pablo@netfilter.org>
Wed, 29 Feb 2012 01:19:19 +0000 (02:19 +0100)
committerPablo Neira Ayuso <pablo@netfilter.org>
Wed, 7 Mar 2012 16:41:28 +0000 (17:41 +0100)
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 <pablo@netfilter.org>
include/linux/netfilter/xt_CT.h
net/netfilter/nf_conntrack_core.c
net/netfilter/nfnetlink_cttimeout.c
net/netfilter/xt_CT.c

index b56e768..a064b8a 100644 (file)
@@ -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 */
index 75398c5..81e2aa4 100644 (file)
@@ -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,
index 29b9897..fec29a4 100644 (file)
@@ -29,6 +29,7 @@
 #include <net/netfilter/nf_conntrack_l3proto.h>
 #include <net/netfilter/nf_conntrack_l4proto.h>
 #include <net/netfilter/nf_conntrack_tuple.h>
+#include <net/netfilter/nf_conntrack_timeout.h>
 
 #include <linux/netfilter/nfnetlink.h>
 #include <linux/netfilter/nfnetlink_cttimeout.h>
@@ -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);
index 0221d10..b873445 100644 (file)
 #include <net/netfilter/nf_conntrack.h>
 #include <net/netfilter/nf_conntrack_helper.h>
 #include <net/netfilter/nf_conntrack_ecache.h>
+#include <net/netfilter/nf_conntrack_timeout.h>
 #include <net/netfilter/nf_conntrack_zones.h>
 
-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);