dev: introduce skb_scrub_packet()

The goal of this new function is to perform all needed cleanup before sending
an skb into another netns.

Signed-off-by: Nicolas Dichtel <nicolas.dichtel@6wind.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index a7393adea0b5cce9cdbaf0eca1c21e14589c0009..6b06023e8a08d7f81303d182cf8c06fc76ac5940 100644 (file)
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -2384,6 +2384,7 @@ extern void              skb_split(struct sk_buff *skb,
                                 struct sk_buff *skb1, const u32 len);
 extern int            skb_shift(struct sk_buff *tgt, struct sk_buff *skb,
                                 int shiftlen);
+extern void           skb_scrub_packet(struct sk_buff *skb);
 
 extern struct sk_buff *skb_segment(struct sk_buff *skb,
                                   netdev_features_t features);

diff --git a/net/core/dev.c b/net/core/dev.c
index 722f633926e062884f44c51c1dbe54de7b8b67f3..370354a9c5f6926e977ce4374541bc4b6e2e5dac 100644 (file)
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -1652,22 +1652,13 @@ int dev_forward_skb(struct net_device *dev, struct sk_buff *skb)
                }
        }
 
-       skb_orphan(skb);
-
        if (unlikely(!is_skb_forwardable(dev, skb))) {
                atomic_long_inc(&dev->rx_dropped);
                kfree_skb(skb);
                return NET_RX_DROP;
        }
-       skb->skb_iif = 0;
-       skb_dst_drop(skb);
-       skb->tstamp.tv64 = 0;
-       skb->pkt_type = PACKET_HOST;
+       skb_scrub_packet(skb);
        skb->protocol = eth_type_trans(skb, dev);
-       skb->mark = 0;
-       secpath_reset(skb);
-       nf_reset(skb);
-       nf_reset_trace(skb);
        return netif_rx(skb);
 }
 EXPORT_SYMBOL_GPL(dev_forward_skb);

diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index 9f73eca29fbe5156303f340664324bc1940a3c0c..b1fcb8727e5640b7c3f19e84d03d3aaa02f1f583 100644 (file)
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -3492,3 +3492,26 @@ bool skb_try_coalesce(struct sk_buff *to, struct sk_buff *from,
        return true;
 }
 EXPORT_SYMBOL(skb_try_coalesce);
+
+/**
+ * skb_scrub_packet - scrub an skb before sending it to another netns
+ *
+ * @skb: buffer to clean
+ *
+ * skb_scrub_packet can be used to clean an skb before injecting it in
+ * another namespace. We have to clear all information in the skb that
+ * could impact namespace isolation.
+ */
+void skb_scrub_packet(struct sk_buff *skb)
+{
+       skb_orphan(skb);
+       skb->tstamp.tv64 = 0;
+       skb->pkt_type = PACKET_HOST;
+       skb->skb_iif = 0;
+       skb_dst_drop(skb);
+       skb->mark = 0;
+       secpath_reset(skb);
+       nf_reset(skb);
+       nf_reset_trace(skb);
+}
+EXPORT_SYMBOL_GPL(skb_scrub_packet);