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, 90 insertions, 5 deletions

diff --git a/net/bridge/netfilter/nft_reject_bridge.c b/net/bridge/netfilter/nft_reject_bridge.c
index ee3ffe93e14e..a76479535df2 100644
--- a/net/bridge/netfilter/nft_reject_bridge.c
+++ b/net/bridge/netfilter/nft_reject_bridge.c
@@ -14,21 +14,106 @@
 #include <linux/netfilter/nf_tables.h>
 #include <net/netfilter/nf_tables.h>
 #include <net/netfilter/nft_reject.h>
+#include <net/netfilter/ipv4/nf_reject.h>
+#include <net/netfilter/ipv6/nf_reject.h>
 
 static void nft_reject_bridge_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 (eth_hdr(pkt->skb)->h_proto) {
         case htons(ETH_P_IP):
-                return nft_reject_ipv4_eval(expr, data, pkt);
+                switch (priv->type) {
+                case NFT_REJECT_ICMP_UNREACH:
+                        nf_send_unreach(pkt->skb, priv->icmp_code);
+                        break;
+                case NFT_REJECT_TCP_RST:
+                        nf_send_reset(pkt->skb, pkt->ops->hooknum);
+                        break;
+                case NFT_REJECT_ICMPX_UNREACH:
+                        nf_send_unreach(pkt->skb,
+                                        nft_reject_icmp_code(priv->icmp_code));
+                        break;
+                }
+                break;
         case htons(ETH_P_IPV6):
-                return nft_reject_ipv6_eval(expr, data, pkt);
+                switch (priv->type) {
+                case NFT_REJECT_ICMP_UNREACH:
+                        nf_send_unreach6(net, pkt->skb, priv->icmp_code,
+                                         pkt->ops->hooknum);
+                        break;
+                case NFT_REJECT_TCP_RST:
+                        nf_send_reset6(net, pkt->skb, pkt->ops->hooknum);
+                        break;
+                case NFT_REJECT_ICMPX_UNREACH:
+                        nf_send_unreach6(net, pkt->skb,
+                                         nft_reject_icmpv6_code(priv->icmp_code),
+                                         pkt->ops->hooknum);
+                        break;
+                }
+                break;
         default:
                 /* No explicit way to reject this protocol, drop it. */
-                data[NFT_REG_VERDICT].verdict = NF_DROP;
                 break;
         }
+        data[NFT_REG_VERDICT].verdict = NF_DROP;
+}
+
+static int nft_reject_bridge_init(const struct nft_ctx *ctx,
+                                  const struct nft_expr *expr,
+                                  const struct nlattr * const tb[])
+{
+        struct nft_reject *priv = nft_expr_priv(expr);
+        int icmp_code;
+
+        if (tb[NFTA_REJECT_TYPE] == NULL)
+                return -EINVAL;
+
+        priv->type = ntohl(nla_get_be32(tb[NFTA_REJECT_TYPE]));
+        switch (priv->type) {
+        case NFT_REJECT_ICMP_UNREACH:
+        case NFT_REJECT_ICMPX_UNREACH:
+                if (tb[NFTA_REJECT_ICMP_CODE] == NULL)
+                        return -EINVAL;
+
+                icmp_code = nla_get_u8(tb[NFTA_REJECT_ICMP_CODE]);
+                if (priv->type == NFT_REJECT_ICMPX_UNREACH &&
+                    icmp_code > NFT_REJECT_ICMPX_MAX)
+                        return -EINVAL;
+
+                priv->icmp_code = icmp_code;
+                break;
+        case NFT_REJECT_TCP_RST:
+                break;
+        default:
+                return -EINVAL;
+        }
+        return 0;
+}
+
+static int nft_reject_bridge_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:
+        case NFT_REJECT_ICMPX_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_bridge_type;
@@ -36,8 +121,8 @@ static const struct nft_expr_ops nft_reject_bridge_ops = {
         .type           = &nft_reject_bridge_type,
         .size           = NFT_EXPR_SIZE(sizeof(struct nft_reject)),
         .eval           = nft_reject_bridge_eval,
-        .init           = nft_reject_init,
-        .dump           = nft_reject_dump,
+        .init           = nft_reject_bridge_init,
+        .dump           = nft_reject_bridge_dump,
 };
 
 static struct nft_expr_type nft_reject_bridge_type __read_mostly = {