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netfilter: meta: add support for setting skb->pkttype 

This allows to redirect bridged packets to local machine:

ether type ip ether daddr set aa:53:08:12:34:56 meta pkttype set unicast
Without 'set unicast', ip stack discards PACKET_OTHERHOST skbs.

It is also useful to add support for a '-m cluster like' nft rule
(where switch floods packets to several nodes, and each cluster node
 node processes a subset of packets for load distribution).

Mangling is restricted to HOST/OTHER/BROAD/MULTICAST, i.e. you cannot set
skb->pkt_type to PACKET_KERNEL or change PACKET_LOOPBACK to PACKET_HOST.

Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
This commit is contained in:
Florian Westphal 2015-12-10 18:04:07 +01:00 committed by Pablo Neira Ayuso
parent 9c55d3b545
commit b4aae759c2
1 changed files with 38 additions and 0 deletions
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38
net/netfilter/nft_meta.c
View File

@ -26,6 +26,8 @@
#include <net/netfilter/nf_tables_core.h>
#include <net/netfilter/nft_meta.h>
#include <uapi/linux/netfilter_bridge.h> /* NF_BR_PRE_ROUTING */
void nft_meta_get_eval(const struct nft_expr *expr,
struct nft_regs *regs,
const struct nft_pktinfo *pkt)
@ -190,6 +192,13 @@ void nft_meta_get_eval(const struct nft_expr *expr,
}
EXPORT_SYMBOL_GPL(nft_meta_get_eval);
/* don't change or set _LOOPBACK, _USER, etc. */
static bool pkt_type_ok(u32 p)
{
return p == PACKET_HOST || p == PACKET_BROADCAST ||
p == PACKET_MULTICAST || p == PACKET_OTHERHOST;
}
void nft_meta_set_eval(const struct nft_expr *expr,
struct nft_regs *regs,
const struct nft_pktinfo *pkt)
@ -205,6 +214,11 @@ void nft_meta_set_eval(const struct nft_expr *expr,
case NFT_META_PRIORITY:
skb->priority = value;
break;
case NFT_META_PKTTYPE:
if (skb->pkt_type != value &&
pkt_type_ok(value) && pkt_type_ok(skb->pkt_type))
skb->pkt_type = value;
break;
case NFT_META_NFTRACE:
skb->nf_trace = 1;
break;
@ -273,6 +287,24 @@ int nft_meta_get_init(const struct nft_ctx *ctx,
}
EXPORT_SYMBOL_GPL(nft_meta_get_init);
static int nft_meta_set_init_pkttype(const struct nft_ctx *ctx)
{
unsigned int hooks;
switch (ctx->afi->family) {
case NFPROTO_BRIDGE:
hooks = 1 << NF_BR_PRE_ROUTING;
break;
case NFPROTO_NETDEV:
hooks = 1 << NF_NETDEV_INGRESS;
break;
default:
return -EOPNOTSUPP;
}
return nft_chain_validate_hooks(ctx->chain, hooks);
}
int nft_meta_set_init(const struct nft_ctx *ctx,
const struct nft_expr *expr,
const struct nlattr * const tb[])
@ -290,6 +322,12 @@ int nft_meta_set_init(const struct nft_ctx *ctx,
case NFT_META_NFTRACE:
len = sizeof(u8);
break;
case NFT_META_PKTTYPE:
err = nft_meta_set_init_pkttype(ctx);
if (err)
return err;
len = sizeof(u8);
break;
default:
return -EOPNOTSUPP;
}