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[XFRM]: Netfilter IPsec output hooks
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Call netfilter hooks before IPsec transforms. Packets visit the
FORWARD/LOCAL_OUT and POST_ROUTING hook before the first encapsulation
and the LOCAL_OUT and POST_ROUTING hook before each following tunnel mode
transform.

Patch from Herbert Xu <herbert@gondor.apana.org.au>:

Move the loop from dst_output into xfrm4_output/xfrm6_output since they're
the only ones who need to it. xfrm{4,6}_output_one() processes the first SA
all subsequent transport mode SAs and is called in a loop that calls the
netfilter hooks between each two calls.

In order to avoid the tail call issue, I've added the inline function
nf_hook which is nf_hook_slow plus the empty list check.

Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
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Patrick McHardy authored and David S. Miller committed Jan 7, 2006
1 parent ee2e684 commit 16a6677
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Showing 4 changed files with 148 additions and 70 deletions.
61 changes: 37 additions & 24 deletions include/linux/netfilter.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -168,6 +168,37 @@ void nf_log_packet(int pf,
const struct net_device *out,
struct nf_loginfo *li,
const char *fmt, ...);

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);

/**
* nf_hook_thresh - call a netfilter hook
*
* Returns 1 if the hook has allowed the packet to pass. The function
* okfn must be invoked by the caller in this case. Any other return
* value indicates the packet has been consumed by the hook.
*/
static inline int nf_hook_thresh(int pf, unsigned int hook,
struct sk_buff **pskb,
struct net_device *indev,
struct net_device *outdev,
int (*okfn)(struct sk_buff *), int thresh)
{
#ifndef CONFIG_NETFILTER_DEBUG
if (list_empty(&nf_hooks[pf][hook]))
return 1;
#endif
return nf_hook_slow(pf, hook, pskb, indev, outdev, okfn, thresh);
}

static inline int nf_hook(int pf, unsigned int hook, struct sk_buff **pskb,
struct net_device *indev, struct net_device *outdev,
int (*okfn)(struct sk_buff *))
{
return nf_hook_thresh(pf, hook, pskb, indev, outdev, okfn, INT_MIN);
}

/* Activate hook; either okfn or kfree_skb called, unless a hook
returns NF_STOLEN (in which case, it's up to the hook to deal with
Expand All @@ -188,35 +219,17 @@ 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) \
({int __ret; \
if ((__ret=nf_hook_slow(pf, hook, &(skb), indev, outdev, okfn, INT_MIN)) == 1) \
__ret = (okfn)(skb); \
__ret;})
#define NF_HOOK_THRESH(pf, hook, skb, indev, outdev, okfn, thresh) \
({int __ret; \
if ((__ret=nf_hook_slow(pf, hook, &(skb), indev, outdev, okfn, thresh)) == 1) \
__ret = (okfn)(skb); \
__ret;})
#else
#define NF_HOOK(pf, hook, skb, indev, outdev, okfn) \
({int __ret; \
if (list_empty(&nf_hooks[pf][hook]) || \
(__ret=nf_hook_slow(pf, hook, &(skb), indev, outdev, okfn, INT_MIN)) == 1) \
__ret = (okfn)(skb); \
__ret;})

/* HX: It's slightly less gross now. */

#define NF_HOOK_THRESH(pf, hook, skb, indev, outdev, okfn, thresh) \
({int __ret; \
if (list_empty(&nf_hooks[pf][hook]) || \
(__ret=nf_hook_slow(pf, hook, &(skb), indev, outdev, okfn, thresh)) == 1) \
if ((__ret=nf_hook_thresh(pf, hook, &(skb), indev, outdev, okfn, thresh)) == 1)\
__ret = (okfn)(skb); \
__ret;})
#endif

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);
#define NF_HOOK(pf, hook, skb, indev, outdev, okfn) \
NF_HOOK_THRESH(pf, hook, skb, indev, outdev, okfn, INT_MIN)

/* Call setsockopt() */
int nf_setsockopt(struct sock *sk, int pf, int optval, char __user *opt,
Expand Down
11 changes: 1 addition & 10 deletions include/net/dst.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -225,16 +225,7 @@ static inline void dst_set_expires(struct dst_entry *dst, int timeout)
/* Output packet to network from transport. */
static inline int dst_output(struct sk_buff *skb)
{
int err;

for (;;) {
err = skb->dst->output(skb);

if (likely(err == 0))
return err;
if (unlikely(err != NET_XMIT_BYPASS))
return err;
}
return skb->dst->output(skb);
}

/* Input packet from network to transport. */
Expand Down
71 changes: 54 additions & 17 deletions net/ipv4/xfrm4_output.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -8,8 +8,10 @@
* 2 of the License, or (at your option) any later version.
*/

#include <linux/compiler.h>
#include <linux/skbuff.h>
#include <linux/spinlock.h>
#include <linux/netfilter_ipv4.h>
#include <net/inet_ecn.h>
#include <net/ip.h>
#include <net/xfrm.h>
Expand Down Expand Up @@ -95,7 +97,7 @@ static int xfrm4_tunnel_check_size(struct sk_buff *skb)
return ret;
}

int xfrm4_output(struct sk_buff *skb)
static int xfrm4_output_one(struct sk_buff *skb)
{
struct dst_entry *dst = skb->dst;
struct xfrm_state *x = dst->xfrm;
Expand All @@ -113,27 +115,32 @@ int xfrm4_output(struct sk_buff *skb)
goto error_nolock;
}

spin_lock_bh(&x->lock);
err = xfrm_state_check(x, skb);
if (err)
goto error;
do {
spin_lock_bh(&x->lock);
err = xfrm_state_check(x, skb);
if (err)
goto error;

xfrm4_encap(skb);
xfrm4_encap(skb);

err = x->type->output(x, skb);
if (err)
goto error;
err = x->type->output(x, skb);
if (err)
goto error;

x->curlft.bytes += skb->len;
x->curlft.packets++;
x->curlft.bytes += skb->len;
x->curlft.packets++;

spin_unlock_bh(&x->lock);
spin_unlock_bh(&x->lock);

if (!(skb->dst = dst_pop(dst))) {
err = -EHOSTUNREACH;
goto error_nolock;
}
err = NET_XMIT_BYPASS;
if (!(skb->dst = dst_pop(dst))) {
err = -EHOSTUNREACH;
goto error_nolock;
}
dst = skb->dst;
x = dst->xfrm;
} while (x && !x->props.mode);

err = 0;

out_exit:
return err;
Expand All @@ -143,3 +150,33 @@ int xfrm4_output(struct sk_buff *skb)
kfree_skb(skb);
goto out_exit;
}

static int xfrm4_output_finish(struct sk_buff *skb)
{
int err;

while (likely((err = xfrm4_output_one(skb)) == 0)) {
nf_reset(skb);

err = nf_hook(PF_INET, NF_IP_LOCAL_OUT, &skb, NULL,
skb->dst->dev, dst_output);
if (unlikely(err != 1))
break;

if (!skb->dst->xfrm)
return dst_output(skb);

err = nf_hook(PF_INET, NF_IP_POST_ROUTING, &skb, NULL,
skb->dst->dev, xfrm4_output_finish);
if (unlikely(err != 1))
break;
}

return err;
}

int xfrm4_output(struct sk_buff *skb)
{
return NF_HOOK(PF_INET, NF_IP_POST_ROUTING, skb, NULL, skb->dst->dev,
xfrm4_output_finish);
}
75 changes: 56 additions & 19 deletions net/ipv6/xfrm6_output.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -9,9 +9,11 @@
* 2 of the License, or (at your option) any later version.
*/

#include <linux/compiler.h>
#include <linux/skbuff.h>
#include <linux/spinlock.h>
#include <linux/icmpv6.h>
#include <linux/netfilter_ipv6.h>
#include <net/dsfield.h>
#include <net/inet_ecn.h>
#include <net/ipv6.h>
Expand Down Expand Up @@ -92,7 +94,7 @@ static int xfrm6_tunnel_check_size(struct sk_buff *skb)
return ret;
}

int xfrm6_output(struct sk_buff *skb)
static int xfrm6_output_one(struct sk_buff *skb)
{
struct dst_entry *dst = skb->dst;
struct xfrm_state *x = dst->xfrm;
Expand All @@ -110,29 +112,34 @@ int xfrm6_output(struct sk_buff *skb)
goto error_nolock;
}

spin_lock_bh(&x->lock);
err = xfrm_state_check(x, skb);
if (err)
goto error;
do {
spin_lock_bh(&x->lock);
err = xfrm_state_check(x, skb);
if (err)
goto error;

xfrm6_encap(skb);
xfrm6_encap(skb);

err = x->type->output(x, skb);
if (err)
goto error;
err = x->type->output(x, skb);
if (err)
goto error;

x->curlft.bytes += skb->len;
x->curlft.packets++;
x->curlft.bytes += skb->len;
x->curlft.packets++;

spin_unlock_bh(&x->lock);
spin_unlock_bh(&x->lock);

skb->nh.raw = skb->data;

if (!(skb->dst = dst_pop(dst))) {
err = -EHOSTUNREACH;
goto error_nolock;
}
err = NET_XMIT_BYPASS;
skb->nh.raw = skb->data;

if (!(skb->dst = dst_pop(dst))) {
err = -EHOSTUNREACH;
goto error_nolock;
}
dst = skb->dst;
x = dst->xfrm;
} while (x && !x->props.mode);

err = 0;

out_exit:
return err;
Expand All @@ -142,3 +149,33 @@ int xfrm6_output(struct sk_buff *skb)
kfree_skb(skb);
goto out_exit;
}

static int xfrm6_output_finish(struct sk_buff *skb)
{
int err;

while (likely((err = xfrm6_output_one(skb)) == 0)) {
nf_reset(skb);

err = nf_hook(PF_INET6, NF_IP6_LOCAL_OUT, &skb, NULL,
skb->dst->dev, dst_output);
if (unlikely(err != 1))
break;

if (!skb->dst->xfrm)
return dst_output(skb);

err = nf_hook(PF_INET6, NF_IP6_POST_ROUTING, &skb, NULL,
skb->dst->dev, xfrm6_output_finish);
if (unlikely(err != 1))
break;
}

return err;
}

int xfrm6_output(struct sk_buff *skb)
{
return NF_HOOK(PF_INET6, NF_IP6_POST_ROUTING, skb, NULL, skb->dst->dev,
xfrm6_output_finish);
}

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