netfilter: nf_tables: add last expression

Add a new optional expression that tells you when last matching on a
given rule / set element element has happened.

Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

diff --git a/include/net/netfilter/nf_tables_core.h b/include/net/netfilter/nf_tables_core.h
index 46c8d5bb5d8dd952ec13bde7079c49ba06fbed62..0fa5a6d98a00b1f5006af6873b3875068bd68436 100644 (file)
--- a/include/net/netfilter/nf_tables_core.h
+++ b/include/net/netfilter/nf_tables_core.h
@@ -16,6 +16,7 @@ extern struct nft_expr_type nft_range_type;
 extern struct nft_expr_type nft_meta_type;
 extern struct nft_expr_type nft_rt_type;
 extern struct nft_expr_type nft_exthdr_type;
+extern struct nft_expr_type nft_last_type;
 
 #ifdef CONFIG_NETWORK_SECMARK
 extern struct nft_object_type nft_secmark_obj_type;

diff --git a/include/uapi/linux/netfilter/nf_tables.h b/include/uapi/linux/netfilter/nf_tables.h
index 19715e2679d19c3d4aad9979628e327335a876dd..e94d1fa554cb224da089742468739b7f36f38395 100644 (file)
--- a/include/uapi/linux/netfilter/nf_tables.h
+++ b/include/uapi/linux/netfilter/nf_tables.h
@@ -1195,6 +1195,21 @@ enum nft_counter_attributes {
 };
 #define NFTA_COUNTER_MAX       (__NFTA_COUNTER_MAX - 1)
 
+/**
+ * enum nft_last_attributes - nf_tables last expression netlink attributes
+ *
+ * @NFTA_LAST_SET: last update has been set, zero means never updated (NLA_U32)
+ * @NFTA_LAST_MSECS: milliseconds since last update (NLA_U64)
+ */
+enum nft_last_attributes {
+       NFTA_LAST_UNSPEC,
+       NFTA_LAST_SET,
+       NFTA_LAST_MSECS,
+       NFTA_LAST_PAD,
+       __NFTA_LAST_MAX
+};
+#define NFTA_LAST_MAX  (__NFTA_LAST_MAX - 1)
+
 /**
  * enum nft_log_attributes - nf_tables log expression netlink attributes
  *

diff --git a/net/netfilter/Makefile b/net/netfilter/Makefile
index 87112dad1fd4864a0a3b44d3209f864117f4bb38..049890e00a3d678a5021e3976cd0cf0abd94c8b0 100644 (file)
--- a/net/netfilter/Makefile
+++ b/net/netfilter/Makefile
@@ -74,7 +74,7 @@ obj-$(CONFIG_NF_DUP_NETDEV)   += nf_dup_netdev.o
 nf_tables-objs := nf_tables_core.o nf_tables_api.o nft_chain_filter.o \
                  nf_tables_trace.o nft_immediate.o nft_cmp.o nft_range.o \
                  nft_bitwise.o nft_byteorder.o nft_payload.o nft_lookup.o \
-                 nft_dynset.o nft_meta.o nft_rt.o nft_exthdr.o \
+                 nft_dynset.o nft_meta.o nft_rt.o nft_exthdr.o nft_last.o \
                  nft_chain_route.o nf_tables_offload.o \
                  nft_set_hash.o nft_set_bitmap.o nft_set_rbtree.o \
                  nft_set_pipapo.o

diff --git a/net/netfilter/nf_tables_core.c b/net/netfilter/nf_tables_core.c
index 7780342e2f2dd22364db4c0edf4bb9f05e182fd1..866cfba04d6c013098db08876c0867b282221d31 100644 (file)
--- a/net/netfilter/nf_tables_core.c
+++ b/net/netfilter/nf_tables_core.c
@@ -268,6 +268,7 @@ static struct nft_expr_type *nft_basic_types[] = {
        &nft_meta_type,
        &nft_rt_type,
        &nft_exthdr_type,
+       &nft_last_type,
 };
 
 static struct nft_object_type *nft_basic_objects[] = {

diff --git a/net/netfilter/nft_last.c b/net/netfilter/nft_last.c
new file mode 100644 (file)
index 0000000..913ac45
--- /dev/null
+++ b/net/netfilter/nft_last.c
@@ -0,0 +1,87 @@
+// SPDX-License-Identifier: GPL-2.0-only
+#include <linux/kernel.h>
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/netlink.h>
+#include <linux/netfilter.h>
+#include <linux/netfilter/nf_tables.h>
+#include <net/netfilter/nf_tables_core.h>
+#include <net/netfilter/nf_tables.h>
+
+struct nft_last_priv {
+       unsigned long   last_jiffies;
+       unsigned int    last_set;
+};
+
+static const struct nla_policy nft_last_policy[NFTA_LAST_MAX + 1] = {
+       [NFTA_LAST_SET] = { .type = NLA_U32 },
+       [NFTA_LAST_MSECS] = { .type = NLA_U64 },
+};
+
+static int nft_last_init(const struct nft_ctx *ctx, const struct nft_expr *expr,
+                        const struct nlattr * const tb[])
+{
+       struct nft_last_priv *priv = nft_expr_priv(expr);
+       u64 last_jiffies;
+       int err;
+
+       if (tb[NFTA_LAST_MSECS]) {
+               err = nf_msecs_to_jiffies64(tb[NFTA_LAST_MSECS], &last_jiffies);
+               if (err < 0)
+                       return err;
+
+               priv->last_jiffies = jiffies + (unsigned long)last_jiffies;
+               priv->last_set = 1;
+       }
+
+       return 0;
+}
+
+static void nft_last_eval(const struct nft_expr *expr,
+                         struct nft_regs *regs, const struct nft_pktinfo *pkt)
+{
+       struct nft_last_priv *priv = nft_expr_priv(expr);
+
+       priv->last_jiffies = jiffies;
+       priv->last_set = 1;
+}
+
+static int nft_last_dump(struct sk_buff *skb, const struct nft_expr *expr)
+{
+       struct nft_last_priv *priv = nft_expr_priv(expr);
+       __be64 msecs;
+
+       if (time_before(jiffies, priv->last_jiffies))
+               priv->last_set = 0;
+
+       if (priv->last_set)
+               msecs = nf_jiffies64_to_msecs(jiffies - priv->last_jiffies);
+       else
+               msecs = 0;
+
+       if (nla_put_be32(skb, NFTA_LAST_SET, htonl(priv->last_set)) ||
+           nla_put_be64(skb, NFTA_LAST_MSECS, msecs, NFTA_LAST_PAD))
+               goto nla_put_failure;
+
+       return 0;
+
+nla_put_failure:
+       return -1;
+}
+
+static const struct nft_expr_ops nft_last_ops = {
+       .type           = &nft_last_type,
+       .size           = NFT_EXPR_SIZE(sizeof(struct nft_last_priv)),
+       .eval           = nft_last_eval,
+       .init           = nft_last_init,
+       .dump           = nft_last_dump,
+};
+
+struct nft_expr_type nft_last_type __read_mostly = {
+       .name           = "last",
+       .ops            = &nft_last_ops,
+       .policy         = nft_last_policy,
+       .maxattr        = NFTA_LAST_MAX,
+       .flags          = NFT_EXPR_STATEFUL,
+       .owner          = THIS_MODULE,
+};