path: root/src/netlink_linearize.c
diff options
authorFlorian Westphal <>2016-09-15 17:28:00 +0200
committerFlorian Westphal <>2016-10-28 13:17:44 +0200
commit4a75ed32132d8e2292dd276f3ea7f4edec4f3d06 (patch)
tree1c095dc262a953ebb816d1770ccbdef1724e3e00 /src/netlink_linearize.c
parentdfd92948a0a88a9f245e71c1cfb63ae670e6e7c1 (diff)
src: add fib expression
This adds the 'fib' expression which can be used to obtain the output interface from the route table based on either source or destination address of a packet. This can be used to e.g. add reverse path filtering: # drop if not coming from the same interface packet # arrived on # nft add rule x prerouting fib saddr . iif oif eq 0 drop # accept only if from eth0 # nft add rule x prerouting fib saddr . iif oif eq "eth0" accept # accept if from any valid interface # nft add rule x prerouting fib saddr oif accept Querying of address type is also supported. This can be used to e.g. only accept packets to addresses configured in the same interface: # fib daddr . iif type local Its also possible to use mark and verdict map, e.g.: # nft add rule x prerouting meta mark set 0xdead fib daddr . mark type vmap { blackhole : drop, prohibit : drop, unicast : accept } Signed-off-by: Florian Westphal <>
Diffstat (limited to 'src/netlink_linearize.c')
1 files changed, 16 insertions, 0 deletions
diff --git a/src/netlink_linearize.c b/src/netlink_linearize.c
index a5d4502f..b5967d49 100644
--- a/src/netlink_linearize.c
+++ b/src/netlink_linearize.c
@@ -104,6 +104,20 @@ static void netlink_gen_concat(struct netlink_linearize_ctx *ctx,
+static void netlink_gen_fib(struct netlink_linearize_ctx *ctx,
+ const struct expr *expr,
+ enum nft_registers dreg)
+ struct nftnl_expr *nle;
+ nle = alloc_nft_expr("fib");
+ netlink_put_register(nle, NFTNL_EXPR_FIB_DREG, dreg);
+ nftnl_expr_set_u32(nle, NFTNL_EXPR_FIB_RESULT, expr->fib.result);
+ nftnl_expr_set_u32(nle, NFTNL_EXPR_FIB_FLAGS, expr->fib.flags);
+ nftnl_rule_add_expr(ctx->nlr, nle);
static void netlink_gen_hash(struct netlink_linearize_ctx *ctx,
const struct expr *expr,
enum nft_registers dreg)
@@ -663,6 +677,8 @@ static void netlink_gen_expr(struct netlink_linearize_ctx *ctx,
return netlink_gen_numgen(ctx, expr, dreg);
return netlink_gen_hash(ctx, expr, dreg);
+ case EXPR_FIB:
+ return netlink_gen_fib(ctx, expr, dreg);
BUG("unknown expression type %s\n", expr->ops->name);