netfilter: nft_reject: introduce icmp code abstraction for inet and bridge

This patch introduces the NFT_REJECT_ICMPX_UNREACH type which provides
an abstraction to the ICMP and ICMPv6 codes that you can use from the
inet and bridge tables, they are:

* NFT_REJECT_ICMPX_NO_ROUTE: no route to host - network unreachable
* NFT_REJECT_ICMPX_PORT_UNREACH: port unreachable
* NFT_REJECT_ICMPX_HOST_UNREACH: host unreachable
* NFT_REJECT_ICMPX_ADMIN_PROHIBITED: administratevely prohibited

You can still use the specific codes when restricting the rule to match
the corresponding layer 3 protocol.

I decided to not overload the existing NFT_REJECT_ICMP_UNREACH to have
different semantics depending on the table family and to allow the user
to specify ICMP family specific codes if they restrict it to the
corresponding family.

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

1 files changed, 37 insertions, 0 deletions

diff --git a/net/netfilter/nft_reject.c b/net/netfilter/nft_reject.c
index f3448c2964468a..ec8a456092a73d 100644
--- a/net/netfilter/nft_reject.c
+++ b/net/netfilter/nft_reject.c
@@ -17,6 +17,8 @@
 #include <linux/netfilter/nf_tables.h>
 #include <net/netfilter/nf_tables.h>
 #include <net/netfilter/nft_reject.h>
+#include <linux/icmp.h>
+#include <linux/icmpv6.h>
 
 const struct nla_policy nft_reject_policy[NFTA_REJECT_MAX + 1] = {
 	[NFTA_REJECT_TYPE]		= { .type = NLA_U32 },
@@ -70,5 +72,40 @@ nla_put_failure:
 }
 EXPORT_SYMBOL_GPL(nft_reject_dump);
 
+static u8 icmp_code_v4[NFT_REJECT_ICMPX_MAX] = {
+	[NFT_REJECT_ICMPX_NO_ROUTE]		= ICMP_NET_UNREACH,
+	[NFT_REJECT_ICMPX_PORT_UNREACH]		= ICMP_PORT_UNREACH,
+	[NFT_REJECT_ICMPX_HOST_UNREACH]		= ICMP_HOST_UNREACH,
+	[NFT_REJECT_ICMPX_ADMIN_PROHIBITED]	= ICMP_PKT_FILTERED,
+};
+
+int nft_reject_icmp_code(u8 code)
+{
+	if (code > NFT_REJECT_ICMPX_MAX)
+		return -EINVAL;
+
+	return icmp_code_v4[code];
+}
+
+EXPORT_SYMBOL_GPL(nft_reject_icmp_code);
+
+
+static u8 icmp_code_v6[NFT_REJECT_ICMPX_MAX] = {
+	[NFT_REJECT_ICMPX_NO_ROUTE]		= ICMPV6_NOROUTE,
+	[NFT_REJECT_ICMPX_PORT_UNREACH]		= ICMPV6_PORT_UNREACH,
+	[NFT_REJECT_ICMPX_HOST_UNREACH]		= ICMPV6_ADDR_UNREACH,
+	[NFT_REJECT_ICMPX_ADMIN_PROHIBITED]	= ICMPV6_ADM_PROHIBITED,
+};
+
+int nft_reject_icmpv6_code(u8 code)
+{
+	if (code > NFT_REJECT_ICMPX_MAX)
+		return -EINVAL;
+
+	return icmp_code_v6[code];
+}
+
+EXPORT_SYMBOL_GPL(nft_reject_icmpv6_code);
+
 MODULE_LICENSE("GPL");
 MODULE_AUTHOR("Patrick McHardy <kaber@trash.net>");