netfilter: nft_ct: add ct timeout support

This patch allows to add, list and delete connection tracking timeout
policies via nft objref infrastructure and assigning these timeout
via nft rule.

%./libnftnl/examples/nft-ct-timeout-add ip raw cttime tcp

Ruleset:

table ip raw {
   ct timeout cttime {
       protocol tcp;
       policy = {established: 111, close: 13 }
   }

   chain output {
       type filter hook output priority -300; policy accept;
       ct timeout set "cttime"
   }
}

%./libnftnl/examples/nft-rule-ct-timeout-add ip raw output cttime

%conntrack -E
[NEW] tcp      6 111 ESTABLISHED src=172.16.19.128 dst=172.16.19.1
sport=22 dport=41360 [UNREPLIED] src=172.16.19.1 dst=172.16.19.128
sport=41360 dport=22

%nft delete rule ip raw output handle <handle>
%./libnftnl/examples/nft-ct-timeout-del ip raw cttime

Joint work with Pablo Neira.

Signed-off-by: Harsha Sharma <harshasharmaiitr@gmail.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

2 files changed, 216 insertions, 2 deletions

diff --git a/include/uapi/linux/netfilter/nf_tables.h b/include/uapi/linux/netfilter/nf_tables.h
index 94657c701f22..e23290ffdc77 100644
--- a/include/uapi/linux/netfilter/nf_tables.h
+++ b/include/uapi/linux/netfilter/nf_tables.h
@@ -958,6 +958,7 @@ enum nft_socket_keys {
  * @NFT_CT_DST_IP: conntrack layer 3 protocol destination (IPv4 address)
  * @NFT_CT_SRC_IP6: conntrack layer 3 protocol source (IPv6 address)
  * @NFT_CT_DST_IP6: conntrack layer 3 protocol destination (IPv6 address)
+ * @NFT_CT_TIMEOUT: connection tracking timeout policy assigned to conntrack
  */
 enum nft_ct_keys {
         NFT_CT_STATE,
@@ -983,6 +984,7 @@ enum nft_ct_keys {
         NFT_CT_DST_IP,
         NFT_CT_SRC_IP6,
         NFT_CT_DST_IP6,
+        NFT_CT_TIMEOUT,
         __NFT_CT_MAX
 };
 #define NFT_CT_MAX              (__NFT_CT_MAX - 1)
@@ -1411,6 +1413,15 @@ enum nft_ct_helper_attributes {
 };
 #define NFTA_CT_HELPER_MAX      (__NFTA_CT_HELPER_MAX - 1)
 
+enum nft_ct_timeout_timeout_attributes {
+        NFTA_CT_TIMEOUT_UNSPEC,
+        NFTA_CT_TIMEOUT_L3PROTO,
+        NFTA_CT_TIMEOUT_L4PROTO,
+        NFTA_CT_TIMEOUT_DATA,
+        __NFTA_CT_TIMEOUT_MAX,
+};
+#define NFTA_CT_TIMEOUT_MAX     (__NFTA_CT_TIMEOUT_MAX - 1)
+
 #define NFT_OBJECT_UNSPEC       0
 #define NFT_OBJECT_COUNTER      1
 #define NFT_OBJECT_QUOTA        2
@@ -1418,7 +1429,8 @@ enum nft_ct_helper_attributes {
 #define NFT_OBJECT_LIMIT        4
 #define NFT_OBJECT_CONNLIMIT    5
 #define NFT_OBJECT_TUNNEL       6
-#define __NFT_OBJECT_MAX        7
+#define NFT_OBJECT_CT_TIMEOUT   7
+#define __NFT_OBJECT_MAX        8
 #define NFT_OBJECT_MAX          (__NFT_OBJECT_MAX - 1)
 
 /**
diff --git a/net/netfilter/nft_ct.c b/net/netfilter/nft_ct.c
index 3bc82ee5464d..4788458a0931 100644
--- a/net/netfilter/nft_ct.c
+++ b/net/netfilter/nft_ct.c
@@ -22,6 +22,8 @@
 #include <net/netfilter/nf_conntrack_helper.h>
 #include <net/netfilter/nf_conntrack_ecache.h>
 #include <net/netfilter/nf_conntrack_labels.h>
+#include <net/netfilter/nf_conntrack_timeout.h>
+#include <net/netfilter/nf_conntrack_l4proto.h>
 
 struct nft_ct {
         enum nft_ct_keys        key:8;
@@ -765,6 +767,194 @@ static struct nft_expr_type nft_notrack_type __read_mostly = {
         .owner          = THIS_MODULE,
 };
 
+#ifdef CONFIG_NF_CONNTRACK_TIMEOUT
+static int
+nft_ct_timeout_parse_policy(void *timeouts,
+                            const struct nf_conntrack_l4proto *l4proto,
+                            struct net *net, const struct nlattr *attr)
+{
+        struct nlattr **tb;
+        int ret = 0;
+
+        if (!l4proto->ctnl_timeout.nlattr_to_obj)
+                return 0;
+
+        tb = kcalloc(l4proto->ctnl_timeout.nlattr_max + 1, sizeof(*tb),
+                     GFP_KERNEL);
+
+        if (!tb)
+                return -ENOMEM;
+
+        ret = nla_parse_nested(tb, l4proto->ctnl_timeout.nlattr_max,
+                               attr, l4proto->ctnl_timeout.nla_policy,
+                               NULL);
+        if (ret < 0)
+                goto err;
+
+        ret = l4proto->ctnl_timeout.nlattr_to_obj(tb, net, timeouts);
+
+err:
+        kfree(tb);
+        return ret;
+}
+
+struct nft_ct_timeout_obj {
+        struct nf_conn          *tmpl;
+        u8                      l4proto;
+};
+
+static void nft_ct_timeout_obj_eval(struct nft_object *obj,
+                                    struct nft_regs *regs,
+                                    const struct nft_pktinfo *pkt)
+{
+        const struct nft_ct_timeout_obj *priv = nft_obj_data(obj);
+        struct nf_conn *ct = (struct nf_conn *)skb_nfct(pkt->skb);
+        struct sk_buff *skb = pkt->skb;
+
+        if (ct ||
+            priv->l4proto != pkt->tprot)
+                return;
+
+        nf_ct_set(skb, priv->tmpl, IP_CT_NEW);
+}
+
+static int nft_ct_timeout_obj_init(const struct nft_ctx *ctx,
+                                   const struct nlattr * const tb[],
+                                   struct nft_object *obj)
+{
+        const struct nf_conntrack_zone *zone = &nf_ct_zone_dflt;
+        struct nft_ct_timeout_obj *priv = nft_obj_data(obj);
+        const struct nf_conntrack_l4proto *l4proto;
+        struct nf_conn_timeout *timeout_ext;
+        struct nf_ct_timeout *timeout;
+        int l3num = ctx->family;
+        struct nf_conn *tmpl;
+        __u8 l4num;
+        int ret;
+
+        if (!tb[NFTA_CT_TIMEOUT_L3PROTO] ||
+            !tb[NFTA_CT_TIMEOUT_L4PROTO] ||
+            !tb[NFTA_CT_TIMEOUT_DATA])
+                return -EINVAL;
+
+        l3num = ntohs(nla_get_be16(tb[NFTA_CT_TIMEOUT_L3PROTO]));
+        l4num = nla_get_u8(tb[NFTA_CT_TIMEOUT_L4PROTO]);
+        priv->l4proto = l4num;
+
+        l4proto = nf_ct_l4proto_find_get(l3num, l4num);
+
+        if (l4proto->l4proto != l4num) {
+                ret = -EOPNOTSUPP;
+                goto err_proto_put;
+        }
+
+        timeout = kzalloc(sizeof(struct nf_ct_timeout) +
+                          l4proto->ctnl_timeout.obj_size, GFP_KERNEL);
+        if (timeout == NULL) {
+                ret = -ENOMEM;
+                goto err_proto_put;
+        }
+
+        ret = nft_ct_timeout_parse_policy(&timeout->data, l4proto, ctx->net,
+                                          tb[NFTA_CT_TIMEOUT_DATA]);
+        if (ret < 0)
+                goto err_free_timeout;
+
+        timeout->l3num = l3num;
+        timeout->l4proto = l4proto;
+        tmpl = nf_ct_tmpl_alloc(ctx->net, zone, GFP_ATOMIC);
+        if (!tmpl) {
+                ret = -ENOMEM;
+                goto err_free_timeout;
+        }
+
+        timeout_ext = nf_ct_timeout_ext_add(tmpl, timeout, GFP_ATOMIC);
+        if (!timeout_ext) {
+                ret = -ENOMEM;
+                goto err_free_tmpl;
+        }
+
+        ret = nf_ct_netns_get(ctx->net, ctx->family);
+        if (ret < 0)
+                goto err_free_tmpl;
+
+        priv->tmpl = tmpl;
+
+        return 0;
+
+err_free_tmpl:
+        nf_ct_tmpl_free(tmpl);
+err_free_timeout:
+        kfree(timeout);
+err_proto_put:
+        nf_ct_l4proto_put(l4proto);
+        return ret;
+}
+
+static void nft_ct_timeout_obj_destroy(const struct nft_ctx *ctx,
+                                       struct nft_object *obj)
+{
+        struct nft_ct_timeout_obj *priv = nft_obj_data(obj);
+        struct nf_conn_timeout *t = nf_ct_timeout_find(priv->tmpl);
+        struct nf_ct_timeout *timeout;
+
+        timeout = rcu_dereference_raw(t->timeout);
+        nf_ct_untimeout(ctx->net, timeout);
+        nf_ct_l4proto_put(timeout->l4proto);
+        nf_ct_netns_put(ctx->net, ctx->family);
+        nf_ct_tmpl_free(priv->tmpl);
+}
+
+static int nft_ct_timeout_obj_dump(struct sk_buff *skb,
+                                   struct nft_object *obj, bool reset)
+{
+        const struct nft_ct_timeout_obj *priv = nft_obj_data(obj);
+        const struct nf_conn_timeout *t = nf_ct_timeout_find(priv->tmpl);
+        const struct nf_ct_timeout *timeout = rcu_dereference_raw(t->timeout);
+        struct nlattr *nest_params;
+        int ret;
+
+        if (nla_put_u8(skb, NFTA_CT_TIMEOUT_L4PROTO, timeout->l4proto->l4proto) ||
+            nla_put_be16(skb, NFTA_CT_TIMEOUT_L3PROTO, htons(timeout->l3num)))
+                return -1;
+
+        nest_params = nla_nest_start(skb, NFTA_CT_TIMEOUT_DATA | NLA_F_NESTED);
+        if (!nest_params)
+                return -1;
+
+        ret = timeout->l4proto->ctnl_timeout.obj_to_nlattr(skb, &timeout->data);
+        if (ret < 0)
+                return -1;
+        nla_nest_end(skb, nest_params);
+        return 0;
+}
+
+static const struct nla_policy nft_ct_timeout_policy[NFTA_CT_TIMEOUT_MAX + 1] = {
+        [NFTA_CT_TIMEOUT_L3PROTO] = {.type = NLA_U16 },
+        [NFTA_CT_TIMEOUT_L4PROTO] = {.type = NLA_U8 },
+        [NFTA_CT_TIMEOUT_DATA]    = {.type = NLA_NESTED },
+};
+
+static struct nft_object_type nft_ct_timeout_obj_type;
+
+static const struct nft_object_ops nft_ct_timeout_obj_ops = {
+        .type           = &nft_ct_timeout_obj_type,
+        .size           = sizeof(struct nft_ct_timeout_obj),
+        .eval           = nft_ct_timeout_obj_eval,
+        .init           = nft_ct_timeout_obj_init,
+        .destroy        = nft_ct_timeout_obj_destroy,
+        .dump           = nft_ct_timeout_obj_dump,
+};
+
+static struct nft_object_type nft_ct_timeout_obj_type __read_mostly = {
+        .type           = NFT_OBJECT_CT_TIMEOUT,
+        .ops            = &nft_ct_timeout_obj_ops,
+        .maxattr        = NFTA_CT_TIMEOUT_MAX,
+        .policy         = nft_ct_timeout_policy,
+        .owner          = THIS_MODULE,
+};
+#endif /* CONFIG_NF_CONNTRACK_TIMEOUT */
+
 static int nft_ct_helper_obj_init(const struct nft_ctx *ctx,
                                   const struct nlattr * const tb[],
                                   struct nft_object *obj)
@@ -949,9 +1139,17 @@ static int __init nft_ct_module_init(void)
         err = nft_register_obj(&nft_ct_helper_obj_type);
         if (err < 0)
                 goto err2;
-
+#ifdef CONFIG_NF_CONNTRACK_TIMEOUT
+        err = nft_register_obj(&nft_ct_timeout_obj_type);
+        if (err < 0)
+                goto err3;
+#endif
         return 0;
 
+#ifdef CONFIG_NF_CONNTRACK_TIMEOUT
+err3:
+        nft_unregister_obj(&nft_ct_helper_obj_type);
+#endif
 err2:
         nft_unregister_expr(&nft_notrack_type);
 err1:
@@ -961,6 +1159,9 @@ err1:
 
 static void __exit nft_ct_module_exit(void)
 {
+#ifdef CONFIG_NF_CONNTRACK_TIMEOUT
+        nft_unregister_obj(&nft_ct_timeout_obj_type);
+#endif
         nft_unregister_obj(&nft_ct_helper_obj_type);
         nft_unregister_expr(&nft_notrack_type);
         nft_unregister_expr(&nft_ct_type);
@@ -974,3 +1175,4 @@ MODULE_AUTHOR("Patrick McHardy <kaber@trash.net>");
 MODULE_ALIAS_NFT_EXPR("ct");
 MODULE_ALIAS_NFT_EXPR("notrack");
 MODULE_ALIAS_NFT_OBJ(NFT_OBJECT_CT_HELPER);
+MODULE_ALIAS_NFT_OBJ(NFT_OBJECT_CT_TIMEOUT);