netfilter: nf_tables: add range expression

Inverse ranges != [a,b] are not currently possible because rules are
composites of && operations, and we need to express this:

	data < a || data > b

This patch adds a new range expression. Positive ranges can be already
through two cmp expressions:

	cmp(sreg, data, >=)
	cmp(sreg, data, <=)

This new range expression provides an alternative way to express this.

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 a9060dd..00f4f6b 100644 (file)
--- a/include/net/netfilter/nf_tables_core.h
+++ b/include/net/netfilter/nf_tables_core.h
@@ -28,6 +28,9 @@ extern const struct nft_expr_ops nft_cmp_fast_ops;
 int nft_cmp_module_init(void);
 void nft_cmp_module_exit(void);
 
+int nft_range_module_init(void);
+void nft_range_module_exit(void);
+
 int nft_lookup_module_init(void);
 void nft_lookup_module_exit(void);
 

diff --git a/include/uapi/linux/netfilter/nf_tables.h b/include/uapi/linux/netfilter/nf_tables.h
index 1cf41dd..c6c4477 100644 (file)
--- a/include/uapi/linux/netfilter/nf_tables.h
+++ b/include/uapi/linux/netfilter/nf_tables.h
@@ -546,6 +546,35 @@ enum nft_cmp_attributes {
 };
 #define NFTA_CMP_MAX           (__NFTA_CMP_MAX - 1)
 
+/**
+ * enum nft_range_ops - nf_tables range operator
+ *
+ * @NFT_RANGE_EQ: equal
+ * @NFT_RANGE_NEQ: not equal
+ */
+enum nft_range_ops {
+       NFT_RANGE_EQ,
+       NFT_RANGE_NEQ,
+};
+
+/**
+ * enum nft_range_attributes - nf_tables range expression netlink attributes
+ *
+ * @NFTA_RANGE_SREG: source register of data to compare (NLA_U32: nft_registers)
+ * @NFTA_RANGE_OP: cmp operation (NLA_U32: nft_cmp_ops)
+ * @NFTA_RANGE_FROM_DATA: data range from (NLA_NESTED: nft_data_attributes)
+ * @NFTA_RANGE_TO_DATA: data range to (NLA_NESTED: nft_data_attributes)
+ */
+enum nft_range_attributes {
+       NFTA_RANGE_UNSPEC,
+       NFTA_RANGE_SREG,
+       NFTA_RANGE_OP,
+       NFTA_RANGE_FROM_DATA,
+       NFTA_RANGE_TO_DATA,
+       __NFTA_RANGE_MAX
+};
+#define NFTA_RANGE_MAX         (__NFTA_RANGE_MAX - 1)
+
 enum nft_lookup_flags {
        NFT_LOOKUP_F_INV = (1 << 0),
 };

diff --git a/net/netfilter/Makefile b/net/netfilter/Makefile
index 0c85811..c23c3c8 100644 (file)
--- a/net/netfilter/Makefile
+++ b/net/netfilter/Makefile
@@ -71,8 +71,9 @@ obj-$(CONFIG_NF_DUP_NETDEV)   += nf_dup_netdev.o
 
 # nf_tables
 nf_tables-objs += nf_tables_core.o nf_tables_api.o nf_tables_trace.o
-nf_tables-objs += nft_immediate.o nft_cmp.o nft_lookup.o nft_dynset.o
+nf_tables-objs += nft_immediate.o nft_cmp.o nft_range.o
 nf_tables-objs += nft_bitwise.o nft_byteorder.o nft_payload.o
+nf_tables-objs += nft_lookup.o nft_dynset.o
 
 obj-$(CONFIG_NF_TABLES)                += nf_tables.o
 obj-$(CONFIG_NF_TABLES_INET)   += nf_tables_inet.o

diff --git a/net/netfilter/nf_tables_core.c b/net/netfilter/nf_tables_core.c
index 67259ce..7c94ce0 100644 (file)
--- a/net/netfilter/nf_tables_core.c
+++ b/net/netfilter/nf_tables_core.c
@@ -263,8 +263,13 @@ int __init nf_tables_core_module_init(void)
        if (err < 0)
                goto err7;
 
-       return 0;
+       err = nft_range_module_init();
+       if (err < 0)
+               goto err8;
 
+       return 0;
+err8:
+       nft_dynset_module_exit();
 err7:
        nft_payload_module_exit();
 err6:

diff --git a/net/netfilter/nft_range.c b/net/netfilter/nft_range.c
new file mode 100644 (file)
index 0000000..c6d5358
--- /dev/null
+++ b/net/netfilter/nft_range.c
@@ -0,0 +1,138 @@
+/*
+ * Copyright (c) 2016 Pablo Neira Ayuso <pablo@netfilter.org>
+ *
+ * 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 <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_range_expr {
+       struct nft_data         data_from;
+       struct nft_data         data_to;
+       enum nft_registers      sreg:8;
+       u8                      len;
+       enum nft_range_ops      op:8;
+};
+
+static void nft_range_eval(const struct nft_expr *expr,
+                        struct nft_regs *regs,
+                        const struct nft_pktinfo *pkt)
+{
+       const struct nft_range_expr *priv = nft_expr_priv(expr);
+       bool mismatch;
+       int d1, d2;
+
+       d1 = memcmp(&regs->data[priv->sreg], &priv->data_from, priv->len);
+       d2 = memcmp(&regs->data[priv->sreg], &priv->data_to, priv->len);
+       switch (priv->op) {
+       case NFT_RANGE_EQ:
+               mismatch = (d1 < 0 || d2 > 0);
+               break;
+       case NFT_RANGE_NEQ:
+               mismatch = (d1 >= 0 && d2 <= 0);
+               break;
+       }
+
+       if (mismatch)
+               regs->verdict.code = NFT_BREAK;
+}
+
+static const struct nla_policy nft_range_policy[NFTA_RANGE_MAX + 1] = {
+       [NFTA_RANGE_SREG]               = { .type = NLA_U32 },
+       [NFTA_RANGE_OP]                 = { .type = NLA_U32 },
+       [NFTA_RANGE_FROM_DATA]          = { .type = NLA_NESTED },
+       [NFTA_RANGE_TO_DATA]            = { .type = NLA_NESTED },
+};
+
+static int nft_range_init(const struct nft_ctx *ctx, const struct nft_expr *expr,
+                       const struct nlattr * const tb[])
+{
+       struct nft_range_expr *priv = nft_expr_priv(expr);
+       struct nft_data_desc desc_from, desc_to;
+       int err;
+
+       err = nft_data_init(NULL, &priv->data_from, sizeof(priv->data_from),
+                           &desc_from, tb[NFTA_RANGE_FROM_DATA]);
+       if (err < 0)
+               return err;
+
+       err = nft_data_init(NULL, &priv->data_to, sizeof(priv->data_to),
+                           &desc_to, tb[NFTA_RANGE_TO_DATA]);
+       if (err < 0)
+               goto err1;
+
+       if (desc_from.len != desc_to.len) {
+               err = -EINVAL;
+               goto err2;
+       }
+
+       priv->sreg = nft_parse_register(tb[NFTA_RANGE_SREG]);
+       err = nft_validate_register_load(priv->sreg, desc_from.len);
+       if (err < 0)
+               goto err2;
+
+       priv->op  = ntohl(nla_get_be32(tb[NFTA_RANGE_OP]));
+       priv->len = desc_from.len;
+       return 0;
+err2:
+       nft_data_uninit(&priv->data_to, desc_to.type);
+err1:
+       nft_data_uninit(&priv->data_from, desc_from.type);
+       return err;
+}
+
+static int nft_range_dump(struct sk_buff *skb, const struct nft_expr *expr)
+{
+       const struct nft_range_expr *priv = nft_expr_priv(expr);
+
+       if (nft_dump_register(skb, NFTA_RANGE_SREG, priv->sreg))
+               goto nla_put_failure;
+       if (nla_put_be32(skb, NFTA_RANGE_OP, htonl(priv->op)))
+               goto nla_put_failure;
+
+       if (nft_data_dump(skb, NFTA_RANGE_FROM_DATA, &priv->data_from,
+                         NFT_DATA_VALUE, priv->len) < 0 ||
+           nft_data_dump(skb, NFTA_RANGE_TO_DATA, &priv->data_to,
+                         NFT_DATA_VALUE, priv->len) < 0)
+               goto nla_put_failure;
+       return 0;
+
+nla_put_failure:
+       return -1;
+}
+
+static struct nft_expr_type nft_range_type;
+static const struct nft_expr_ops nft_range_ops = {
+       .type           = &nft_range_type,
+       .size           = NFT_EXPR_SIZE(sizeof(struct nft_range_expr)),
+       .eval           = nft_range_eval,
+       .init           = nft_range_init,
+       .dump           = nft_range_dump,
+};
+
+static struct nft_expr_type nft_range_type __read_mostly = {
+       .name           = "range",
+       .ops            = &nft_range_ops,
+       .policy         = nft_range_policy,
+       .maxattr        = NFTA_RANGE_MAX,
+       .owner          = THIS_MODULE,
+};
+
+int __init nft_range_module_init(void)
+{
+       return nft_register_expr(&nft_range_type);
+}
+
+void nft_range_module_exit(void)
+{
+       nft_unregister_expr(&nft_range_type);
+}