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bridge: netfilter: unroll NF_HOOK helper in bridge input path 

Replace NF_HOOK() based invocation of the netfilter hooks with a private
copy of nf_hook_slow().

This copy has one difference: it can return the rx handler value expected
by the stack, i.e. RX_HANDLER_CONSUMED or RX_HANDLER_PASS.

This is needed by the next patch to invoke the ebtables
"broute" table via the standard netfilter hooks rather than the custom
"br_should_route_hook" indirection that is used now.

When the skb is to be "brouted", we must return RX_HANDLER_PASS from the
bridge rx input handler, but there is no way to indicate this via
NF_HOOK(), unless perhaps by some hack such as exposing bridge_cb in the
netfilter core or a percpu flag.

  text    data     bss     dec   filename
  3369      56       0    3425   net/bridge/br_input.o.before
  3458      40       0    3498   net/bridge/br_input.o.after

This allows removal of the "br_should_route_hook" in the next patch.

Signed-off-by: Florian Westphal <fw@strlen.de>
Acked-by: David S. Miller <davem@davemloft.net>
Acked-by: Nikolay Aleksandrov <nikolay@cumulusnetworks.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
This commit is contained in:
Florian Westphal 2019-04-11 16:36:41 +02:00 committed by Pablo Neira Ayuso
parent f12064d1b4
commit 971502d77f
5 changed files with 56 additions and 7 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

3
include/net/netfilter/nf_queue.h
View File

@ -119,4 +119,7 @@ nfqueue_hash(const struct sk_buff *skb, u16 queue, u16 queues_total, u8 family,
return queue;
}
int nf_queue(struct sk_buff *skb, struct nf_hook_state *state,
const struct nf_hook_entries *entries, unsigned int index,
unsigned int verdict);
#endif /* _NF_QUEUE_H */

55
net/bridge/br_input.c
View File

@ -16,6 +16,7 @@
#include <linux/netdevice.h>
#include <linux/etherdevice.h>
#include <linux/netfilter_bridge.h>
#include <net/netfilter/nf_queue.h>
#include <linux/neighbour.h>
#include <net/arp.h>
#include <linux/export.h>
@ -206,6 +207,55 @@ static int br_handle_local_finish(struct net *net, struct sock *sk, struct sk_bu
return 0;
}
static int nf_hook_bridge_pre(struct sk_buff *skb, struct sk_buff **pskb)
{
#ifdef CONFIG_NETFILTER_FAMILY_BRIDGE
struct nf_hook_entries *e = NULL;
struct nf_hook_state state;
unsigned int verdict, i;
struct net *net;
int ret;
net = dev_net(skb->dev);
#ifdef HAVE_JUMP_LABEL
if (!static_key_false(&nf_hooks_needed[NFPROTO_BRIDGE][NF_BR_PRE_ROUTING]))
goto frame_finish;
#endif
e = rcu_dereference(net->nf.hooks_bridge[NF_BR_PRE_ROUTING]);
if (!e)
goto frame_finish;
nf_hook_state_init(&state, NF_BR_PRE_ROUTING,
NFPROTO_BRIDGE, skb->dev, NULL, NULL,
net, br_handle_frame_finish);
for (i = 0; i < e->num_hook_entries; i++) {
verdict = nf_hook_entry_hookfn(&e->hooks[i], skb, &state);
switch (verdict & NF_VERDICT_MASK) {
case NF_ACCEPT:
break;
case NF_DROP:
kfree_skb(skb);
return RX_HANDLER_CONSUMED;
case NF_QUEUE:
ret = nf_queue(skb, &state, e, i, verdict);
if (ret == 1)
continue;
return RX_HANDLER_CONSUMED;
default: /* STOLEN */
return RX_HANDLER_CONSUMED;
}
}
frame_finish:
net = dev_net(skb->dev);
br_handle_frame_finish(net, NULL, skb);
#else
br_handle_frame_finish(dev_net(skb->dev), NULL, skb);
#endif
return RX_HANDLER_CONSUMED;
}
/*
* Return NULL if skb is handled
* note: already called with rcu_read_lock
@ -304,10 +354,7 @@ forward:
if (ether_addr_equal(p->br->dev->dev_addr, dest))
skb->pkt_type = PACKET_HOST;
NF_HOOK(NFPROTO_BRIDGE, NF_BR_PRE_ROUTING,
dev_net(skb->dev), NULL, skb, skb->dev, NULL,
br_handle_frame_finish);
break;
return nf_hook_bridge_pre(skb, pskb);
default:
drop:
kfree_skb(skb);

1
net/netfilter/core.c
View File

@ -23,6 +23,7 @@
#include <linux/mm.h>
#include <linux/rcupdate.h>
#include <net/net_namespace.h>
#include <net/netfilter/nf_queue.h>
#include <net/sock.h>
#include "nf_internals.h"

3
net/netfilter/nf_internals.h
View File

@ -7,9 +7,6 @@
#include <linux/netdevice.h>
/* nf_queue.c */
int nf_queue(struct sk_buff *skb, struct nf_hook_state *state,
const struct nf_hook_entries *entries, unsigned int index,
unsigned int verdict);
void nf_queue_nf_hook_drop(struct net *net);
/* nf_log.c */

1
net/netfilter/nf_queue.c
View File

@ -240,6 +240,7 @@ int nf_queue(struct sk_buff *skb, struct nf_hook_state *state,
return 0;
}
EXPORT_SYMBOL_GPL(nf_queue);
static unsigned int nf_iterate(struct sk_buff *skb,
struct nf_hook_state *state,