Op di, 18-01-2005 te 13:57 -0800, schreef David S. Miller:
> On Fri, 07 Jan 2005 22:27:21 +0100
> Bart De Schuymer <bdschuym@xxxxxxxxxx> wrote:
>
> > How about something like the patch below (untested but compiles)?
> > The current netfilter scheme adds one function call to the call chain
> > for each NF_HOOK and NF_HOOK_THRESH. This can be prevented by executing
> > the okfn in the calling function instead of in nf_hook_slow().
> > I didn't check if there's any code that actually uses the return value
> > from NF_HOOK. If so, this patch won't work well in its current form as -
> > EPERM is now also returned for NF_QUEUE and NF_STOLEN.
> >
> > Another 2 calls of okfn can be postponed in br_netfilter.c by adding
> > NF_STOP, which would work like NF_STOLEN except that okfn is still
> > called.
> This NF_HOOK() change looks interesting. Could we also do something like
> running the deeper ->hard_start_xmit() via a triggered tasklet or something
> similar?
Hi,
The patch below reduces the call chain length for netfilter hooks by
executing the okfn() inside the caller function instead of inside
nf_hook_slow(). It also reduces the size of netfilter.o from 129590 to
129550 on my system.
The return value for NF_HOOK stays the same as before: 0 except when the
verdict was NF_DROP (in that case the return value becomes -EPERM).
The target NF_STOP is added to postpone two executions of okfn() in
br_netfilter.c, it works like NF_STOLEN except that the okfn() will
still be called.
The downside is that all .o files using NF_HOOK will enlarge.
Comments are welcome.
cheers,
Bart
Signed-off-by: Bart De Schuymer <bdschuym@xxxxxxxxxx>
--- linux-2.6.1-rc1/include/linux/netfilter.h.old 2005-01-20
21:44:22.000000000 +0100
+++ linux-2.6.1-rc1/include/linux/netfilter.h 2005-01-22 22:06:14.000000000
+0100
@@ -18,7 +18,8 @@
#define NF_STOLEN 2
#define NF_QUEUE 3
#define NF_REPEAT 4
-#define NF_MAX_VERDICT NF_REPEAT
+#define NF_STOP 5
+#define NF_MAX_VERDICT NF_STOP
/* Generic cache responses from hook functions.
<= 0x2000 is used for protocol-flags. */
@@ -138,23 +139,34 @@ void nf_log_packet(int pf,
/* This is gross, but inline doesn't cut it for avoiding the function
call in fast path: gcc doesn't inline (needs value tracking?). --RR */
#ifdef CONFIG_NETFILTER_DEBUG
-#define NF_HOOK(pf, hook, skb, indev, outdev, okfn) \
- nf_hook_slow((pf), (hook), (skb), (indev), (outdev), (okfn), INT_MIN)
-#define NF_HOOK_THRESH nf_hook_slow
+#define NF_HOOK(pf, hook, skb, indev, outdev, okfn) \
+({int __ret = 0; \
+if (!nf_hook_slow(pf, hook, &(skb), indev, outdev, okfn, INT_MIN, &__ret); \
+ __ret = (okfn)(skb); \
+__ret;})
+#define NF_HOOK_THRESH(pf, hook, skb, indev, outdev, okfn, thresh) \
+({int __ret = 0; \
+if (!nf_hook_slow(pf, hook, &(skb), indev, outdev, okfn, thresh, &__ret); \
+ __ret = (okfn)(skb); \
+__ret;})
#else
-#define NF_HOOK(pf, hook, skb, indev, outdev, okfn) \
-(list_empty(&nf_hooks[(pf)][(hook)]) \
- ? (okfn)(skb) \
- : nf_hook_slow((pf), (hook), (skb), (indev), (outdev), (okfn), INT_MIN))
-#define NF_HOOK_THRESH(pf, hook, skb, indev, outdev, okfn, thresh) \
-(list_empty(&nf_hooks[(pf)][(hook)]) \
- ? (okfn)(skb) \
- : nf_hook_slow((pf), (hook), (skb), (indev), (outdev), (okfn), (thresh)))
+#define NF_HOOK(pf, hook, skb, indev, outdev, okfn) \
+({int __ret = 0; \
+if (list_empty(&nf_hooks[pf][hook]) || \
+ !nf_hook_slow(pf, hook, &(skb), indev, outdev, okfn, INT_MIN, &__ret)) \
+ __ret = (okfn)(skb); \
+__ret;})
+#define NF_HOOK_THRESH(pf, hook, skb, indev, outdev, okfn, thresh) \
+({int __ret = 0; \
+if (list_empty(&nf_hooks[pf][hook]) || \
+ !nf_hook_slow(pf, hook, &(skb), indev, outdev, okfn, thresh, &__ret)) \
+ __ret = (okfn)(skb); \
+__ret;})
#endif
-int nf_hook_slow(int pf, unsigned int hook, struct sk_buff *skb,
+int nf_hook_slow(int pf, unsigned int hook, struct sk_buff **pskb,
struct net_device *indev, struct net_device *outdev,
- int (*okfn)(struct sk_buff *), int thresh);
+ int (*okfn)(struct sk_buff *), int thresh, int *ret);
/* Call setsockopt() */
int nf_setsockopt(struct sock *sk, int pf, int optval, char __user *opt,
--- linux-2.6.1-rc1/net/core/netfilter.c.old 2005-01-20 21:38:59.000000000
+0100
+++ linux-2.6.1-rc1/net/core/netfilter.c 2005-01-22 22:08:41.000000000
+0100
@@ -349,6 +349,8 @@ static unsigned int nf_iterate(struct li
int (*okfn)(struct sk_buff *),
int hook_thresh)
{
+ unsigned int verdict;
+
/*
* The caller must not block between calls to this
* function because of risk of continuing from deleted element.
@@ -361,28 +363,18 @@ static unsigned int nf_iterate(struct li
/* Optimization: we don't need to hold module
reference here, since function can't sleep. --RR */
- switch (elem->hook(hook, skb, indev, outdev, okfn)) {
- case NF_QUEUE:
- return NF_QUEUE;
-
- case NF_STOLEN:
- return NF_STOLEN;
-
- case NF_DROP:
- return NF_DROP;
-
- case NF_REPEAT:
- *i = (*i)->prev;
- break;
-
+ verdict = elem->hook(hook, skb, indev, outdev, okfn);
+ if (verdict != NF_ACCEPT) {
#ifdef CONFIG_NETFILTER_DEBUG
- case NF_ACCEPT:
- break;
-
- default:
- NFDEBUG("Evil return from %p(%u).\n",
- elem->hook, hook);
+ if (verdict > NF_MAX_VERDICT) {
+ NFDEBUG("Evil return from %p(%u).\n",
+ elem->hook, hook);
+ continue;
+ }
#endif
+ if (verdict != NF_REPEAT)
+ return verdict;
+ *i = (*i)->prev;
}
}
return NF_ACCEPT;
@@ -494,50 +486,47 @@ static int nf_queue(struct sk_buff *skb,
return 1;
}
-int nf_hook_slow(int pf, unsigned int hook, struct sk_buff *skb,
+/* Returns 0 if okfn() needs to be executed by the caller, -EPERM otherwise.
+ * Assumes *ret==0 when called. On return, *ret!=0 when verdict==NF_DROP */
+int nf_hook_slow(int pf, unsigned int hook, struct sk_buff **pskb,
struct net_device *indev,
struct net_device *outdev,
int (*okfn)(struct sk_buff *),
- int hook_thresh)
+ int hook_thresh, int *ret)
{
struct list_head *elem;
unsigned int verdict;
- int ret = 0;
+ int ret2 = 0;
/* We may already have this, but read-locks nest anyway */
rcu_read_lock();
#ifdef CONFIG_NETFILTER_DEBUG
- if (skb->nf_debug & (1 << hook)) {
+ if ((*pskb)->nf_debug & (1 << hook)) {
printk("nf_hook: hook %i already set.\n", hook);
- nf_dump_skb(pf, skb);
+ nf_dump_skb(pf, *pskb);
}
skb->nf_debug |= (1 << hook);
#endif
elem = &nf_hooks[pf][hook];
next_hook:
- verdict = nf_iterate(&nf_hooks[pf][hook], &skb, hook, indev,
+ verdict = nf_iterate(&nf_hooks[pf][hook], pskb, hook, indev,
outdev, &elem, okfn, hook_thresh);
- if (verdict == NF_QUEUE) {
+ if (verdict == NF_ACCEPT || verdict == NF_STOP)
+ goto unlock;
+ else if (verdict == NF_DROP) {
+ kfree_skb(*pskb);
+ *ret = -EPERM;
+ } else if (verdict == NF_QUEUE) {
NFDEBUG("nf_hook: Verdict = QUEUE.\n");
- if (!nf_queue(skb, elem, pf, hook, indev, outdev, okfn))
+ if (!nf_queue(*pskb, elem, pf, hook, indev, outdev, okfn))
goto next_hook;
}
-
- switch (verdict) {
- case NF_ACCEPT:
- ret = okfn(skb);
- break;
-
- case NF_DROP:
- kfree_skb(skb);
- ret = -EPERM;
- break;
- }
-
+ ret2 = -EPERM;
+unlock:
rcu_read_unlock();
- return ret;
+ return ret2;
}
void nf_reinject(struct sk_buff *skb, struct nf_info *info,
--- linux-2.6.1-rc1/net/bridge/br_netfilter.c.old 2005-01-20
21:43:08.000000000 +0100
+++ linux-2.6.1-rc1/net/bridge/br_netfilter.c 2005-01-22 21:20:06.000000000
+0100
@@ -829,8 +829,7 @@ static unsigned int ip_sabotage_in(unsig
{
if ((*pskb)->nf_bridge &&
!((*pskb)->nf_bridge->mask & BRNF_NF_BRIDGE_PREROUTING)) {
- okfn(*pskb);
- return NF_STOLEN;
+ return NF_STOP;
}
return NF_ACCEPT;
@@ -888,8 +887,7 @@ static unsigned int ip_sabotage_out(unsi
if (out->priv_flags & IFF_802_1Q_VLAN)
nf_bridge->netoutdev = (struct net_device *)out;
#endif
- okfn(skb);
- return NF_STOLEN;
+ return NF_STOP;
}
return NF_ACCEPT;
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