[PATCH nf-next] netfilter: nf_tables: rt: allow checking if dst has xfrm attached

[Florian Westphal]

Useful e.g. to avoid NATting inner headers of to-be-encrypted packets.

Signed-off-by: Florian Westphal <f...@strlen.de>
---
 include/uapi/linux/netfilter/nf_tables.h |  2 ++
 net/netfilter/nft_rt.c                   | 11 +++++++++++
 2 files changed, 13 insertions(+)

diff --git a/include/uapi/linux/netfilter/nf_tables.h 
b/include/uapi/linux/netfilter/nf_tables.h
index e23290ffdc77..6c44cbbb2cda 100644
--- a/include/uapi/linux/netfilter/nf_tables.h
+++ b/include/uapi/linux/netfilter/nf_tables.h
@@ -826,12 +826,14 @@ enum nft_meta_keys {
  * @NFT_RT_NEXTHOP4: routing nexthop for IPv4
  * @NFT_RT_NEXTHOP6: routing nexthop for IPv6
  * @NFT_RT_TCPMSS: fetch current path tcp mss
+ * @NFT_RT_XFRM: boolean, skb->dst->xfrm != NULL
  */
 enum nft_rt_keys {
        NFT_RT_CLASSID,
        NFT_RT_NEXTHOP4,
        NFT_RT_NEXTHOP6,
        NFT_RT_TCPMSS,
+       NFT_RT_XFRM,
        __NFT_RT_MAX
 };
 #define NFT_RT_MAX             (__NFT_RT_MAX - 1)
diff --git a/net/netfilter/nft_rt.c b/net/netfilter/nft_rt.c
index 76dba9f6b6f6..f35fa33913ae 100644
--- a/net/netfilter/nft_rt.c
+++ b/net/netfilter/nft_rt.c
@@ -90,6 +90,11 @@ static void nft_rt_get_eval(const struct nft_expr *expr,
        case NFT_RT_TCPMSS:
                nft_reg_store16(dest, get_tcpmss(pkt, dst));
                break;
+#ifdef CONFIG_XFRM
+       case NFT_RT_XFRM:
+               nft_reg_store8(dest, !!dst->xfrm);
+               break;
+#endif
        default:
                WARN_ON(1);
                goto err;
@@ -130,6 +135,11 @@ static int nft_rt_get_init(const struct nft_ctx *ctx,
        case NFT_RT_TCPMSS:
                len = sizeof(u16);
                break;
+#ifdef CONFIG_XFRM
+       case NFT_RT_XFRM:
+               len = sizeof(u8);
+               break;
+#endif
        default:
                return -EOPNOTSUPP;
        }
@@ -164,6 +174,7 @@ static int nft_rt_validate(const struct nft_ctx *ctx, const 
struct nft_expr *exp
        case NFT_RT_NEXTHOP4:
        case NFT_RT_NEXTHOP6:
        case NFT_RT_CLASSID:
+       case NFT_RT_XFRM:
                return 0;
        case NFT_RT_TCPMSS:
                hooks = (1 << NF_INET_FORWARD) |
-- 
2.16.4