diff mbox

[v16,11/17] Add a hook to intercept external buffers from NIC driver.

Message ID c1b20adfd68fc241611845c0ef42fe8fa91ed981.1291187695.git.xiaohui.xin@intel.com
State Changes Requested, archived
Delegated to: David Miller
Headers show

Commit Message

Xin, Xiaohui Dec. 1, 2010, 8:08 a.m. UTC 
From: Xin Xiaohui <xiaohui.xin@intel.com>

The hook is called in __netif_receive_skb().

Signed-off-by: Xin Xiaohui <xiaohui.xin@intel.com>
Signed-off-by: Zhao Yu <yzhao81new@gmail.com>
Reviewed-by: Jeff Dike <jdike@linux.intel.com>
---
 net/core/dev.c |   40 ++++++++++++++++++++++++++++++++++++++++
 1 files changed, 40 insertions(+), 0 deletions(-)

Comments

Changli Gao Dec. 1, 2010, 9:38 a.m. UTC | #1 
On Wed, Dec 1, 2010 at 4:08 PM,  <xiaohui.xin@intel.com> wrote:
> From: Xin Xiaohui <xiaohui.xin@intel.com>
> @@ -2891,6 +2925,11 @@ static int __netif_receive_skb(struct sk_buff *skb)
>  ncls:
>  #endif
>
> +       /* To intercept mediate passthru(zero-copy) packets here */
> +       skb = handle_mpassthru(skb, &pt_prev, &ret, orig_dev);
> +       if (!skb)
> +               goto out;
> +
>        /* Handle special case of bridge or macvlan */

I think it won't work if the skbs is captured by the previous ptype.
We need to trace the skb pages(skb_shared_info.frags[*].page), but
currently, there isn't a easy way to do that. skb pages are treated as
normal pages, and anyone can get it freely. And it is the problem in
the way to fix the potential data corruption bug.

Eric thinks af_packets(mmap) isn't worth fixing. But if this patch
serial has the same problem. It will be worth.

My idea is adding a new function dtor pointer  and some other args
pointers to the struct skb_shared_info. If skb_shared_info.dtor
exists, the pages in skb_shared_info.frags are private to this
skb->head. Anyone who wants to get these pages, should copy them
instead.
diff mbox

Patch

diff --git a/net/core/dev.c b/net/core/dev.c
index 84fbb83..bdad1c8 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -2814,6 +2814,40 @@  int __skb_bond_should_drop(struct sk_buff *skb, struct net_device *master)
 }
 EXPORT_SYMBOL(__skb_bond_should_drop);
 
+#if defined(CONFIG_MEDIATE_PASSTHRU) || defined(CONFIG_MEDIATE_PASSTHRU_MODULE)
+/* Add a hook to intercept mediate passthru(zero-copy) packets,
+ * and insert it to the socket queue owned by mp_port specially.
+ */
+static inline struct sk_buff *handle_mpassthru(struct sk_buff *skb,
+					       struct packet_type **pt_prev,
+					       int *ret,
+					       struct net_device *orig_dev)
+{
+	struct mp_port *mp_port = NULL;
+	struct sock *sk = NULL;
+
+	if (!dev_is_mpassthru(skb->dev) && !dev_is_mpassthru(orig_dev))
+		return skb;
+	if (dev_is_mpassthru(skb->dev))
+		mp_port = skb->dev->mp_port;
+	else if (orig_dev->master == skb->dev && dev_is_mpassthru(orig_dev))
+		mp_port = orig_dev->mp_port;
+
+	if (*pt_prev) {
+		*ret = deliver_skb(skb, *pt_prev, orig_dev);
+		*pt_prev = NULL;
+	}
+
+	sk = mp_port->sock->sk;
+	skb_queue_tail(&sk->sk_receive_queue, skb);
+	sk->sk_state_change(sk);
+
+	return NULL;
+}
+#else
+#define handle_mpassthru(skb, pt_prev, ret, orig_dev)     (skb)
+#endif
+
 static int __netif_receive_skb(struct sk_buff *skb)
 {
 	struct packet_type *ptype, *pt_prev;
@@ -2891,6 +2925,11 @@  static int __netif_receive_skb(struct sk_buff *skb)
 ncls:
 #endif
 
+	/* To intercept mediate passthru(zero-copy) packets here */
+	skb = handle_mpassthru(skb, &pt_prev, &ret, orig_dev);
+	if (!skb)
+		goto out;
+
 	/* Handle special case of bridge or macvlan */
 	rx_handler = rcu_dereference(skb->dev->rx_handler);
 	if (rx_handler) {
@@ -2983,6 +3022,7 @@  err:
 EXPORT_SYMBOL(netdev_mp_port_prep);
 #endif
 
+
 /**
  *	netif_receive_skb - process receive buffer from network
  *	@skb: buffer to process