netfilter: nft_reject: support for IPv6 and TCP reset
This patch moves nft_reject_ipv4 to nft_reject and adds support
for IPv6 protocol. This patch uses functions included in nf_reject.h
to implement reject by TCP reset.
The code has to be build as a module if NF_TABLES_IPV6 is also a
module to avoid compilation error due to usage of IPv6 functions.
This has been done in Kconfig by using the construct:
depends on NF_TABLES_IPV6 || !NF_TABLES_IPV6
This seems a bit weird in terms of syntax but works perfectly.
Signed-off-by: Eric Leblond <eric@regit.org>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
diff --git a/net/netfilter/nft_reject.c b/net/netfilter/nft_reject.c
new file mode 100644
index 0000000..0d690d4
--- /dev/null
+++ b/net/netfilter/nft_reject.c
@@ -0,0 +1,144 @@
+/*
+ * Copyright (c) 2008-2009 Patrick McHardy <kaber@trash.net>
+ * Copyright (c) 2013 Eric Leblond <eric@regit.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.
+ *
+ * Development of this code funded by Astaro AG (http://www.astaro.com/)
+ */
+
+#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.h>
+#include <net/icmp.h>
+#include <net/netfilter/ipv4/nf_reject.h>
+
+#if IS_ENABLED(CONFIG_NF_TABLES_IPV6)
+#include <net/netfilter/ipv6/nf_reject.h>
+#endif
+
+struct nft_reject {
+ enum nft_reject_types type:8;
+ u8 icmp_code;
+ u8 family;
+};
+
+static void nft_reject_eval(const struct nft_expr *expr,
+ struct nft_data data[NFT_REG_MAX + 1],
+ const struct nft_pktinfo *pkt)
+{
+ struct nft_reject *priv = nft_expr_priv(expr);
+ struct net *net = dev_net((pkt->in != NULL) ? pkt->in : pkt->out);
+
+ switch (priv->type) {
+ case NFT_REJECT_ICMP_UNREACH:
+ if (priv->family == NFPROTO_IPV4)
+ nf_send_unreach(pkt->skb, priv->icmp_code);
+#if IS_ENABLED(CONFIG_NF_TABLES_IPV6)
+ else if (priv->family == NFPROTO_IPV6)
+ nf_send_unreach6(net, pkt->skb, priv->icmp_code,
+ pkt->hooknum);
+#endif
+ break;
+ case NFT_REJECT_TCP_RST:
+ if (priv->family == NFPROTO_IPV4)
+ nf_send_reset(pkt->skb, pkt->hooknum);
+#if IS_ENABLED(CONFIG_NF_TABLES_IPV6)
+ else if (priv->family == NFPROTO_IPV6)
+ nf_send_reset6(net, pkt->skb, pkt->hooknum);
+#endif
+ break;
+ }
+
+ data[NFT_REG_VERDICT].verdict = NF_DROP;
+}
+
+static const struct nla_policy nft_reject_policy[NFTA_REJECT_MAX + 1] = {
+ [NFTA_REJECT_TYPE] = { .type = NLA_U32 },
+ [NFTA_REJECT_ICMP_CODE] = { .type = NLA_U8 },
+};
+
+static int nft_reject_init(const struct nft_ctx *ctx,
+ const struct nft_expr *expr,
+ const struct nlattr * const tb[])
+{
+ struct nft_reject *priv = nft_expr_priv(expr);
+
+ if (tb[NFTA_REJECT_TYPE] == NULL)
+ return -EINVAL;
+
+ priv->family = ctx->afi->family;
+ priv->type = ntohl(nla_get_be32(tb[NFTA_REJECT_TYPE]));
+ switch (priv->type) {
+ case NFT_REJECT_ICMP_UNREACH:
+ if (tb[NFTA_REJECT_ICMP_CODE] == NULL)
+ return -EINVAL;
+ priv->icmp_code = nla_get_u8(tb[NFTA_REJECT_ICMP_CODE]);
+ case NFT_REJECT_TCP_RST:
+ break;
+ default:
+ return -EINVAL;
+ }
+
+ return 0;
+}
+
+static int nft_reject_dump(struct sk_buff *skb, const struct nft_expr *expr)
+{
+ const struct nft_reject *priv = nft_expr_priv(expr);
+
+ if (nla_put_be32(skb, NFTA_REJECT_TYPE, htonl(priv->type)))
+ goto nla_put_failure;
+
+ switch (priv->type) {
+ case NFT_REJECT_ICMP_UNREACH:
+ if (nla_put_u8(skb, NFTA_REJECT_ICMP_CODE, priv->icmp_code))
+ goto nla_put_failure;
+ break;
+ }
+
+ return 0;
+
+nla_put_failure:
+ return -1;
+}
+
+static struct nft_expr_type nft_reject_type;
+static const struct nft_expr_ops nft_reject_ops = {
+ .type = &nft_reject_type,
+ .size = NFT_EXPR_SIZE(sizeof(struct nft_reject)),
+ .eval = nft_reject_eval,
+ .init = nft_reject_init,
+ .dump = nft_reject_dump,
+};
+
+static struct nft_expr_type nft_reject_type __read_mostly = {
+ .name = "reject",
+ .ops = &nft_reject_ops,
+ .policy = nft_reject_policy,
+ .maxattr = NFTA_REJECT_MAX,
+ .owner = THIS_MODULE,
+};
+
+static int __init nft_reject_module_init(void)
+{
+ return nft_register_expr(&nft_reject_type);
+}
+
+static void __exit nft_reject_module_exit(void)
+{
+ nft_unregister_expr(&nft_reject_type);
+}
+
+module_init(nft_reject_module_init);
+module_exit(nft_reject_module_exit);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Patrick McHardy <kaber@trash.net>");
+MODULE_ALIAS_NFT_EXPR("reject");