[AF_PACKET]: Add option to return orig_dev to userspace.

Add a packet socket option to allow the orig_dev index to be returned
to userspace when passing traffic through a decapsulated device, such
as the bonding driver.

This is very useful for layer 2 traffic being able to report which
physical device actually received the traffic, instead of having the
encapsulating device hide that information.

The new option is called PACKET_ORIGDEV.

Signed-off-by: Peter P. Waskiewicz Jr. <peter.p.waskiewicz.jr@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

2 files changed, 30 insertions, 3 deletions

diff --git a/include/linux/if_packet.h b/include/linux/if_packet.h
index f3de05c30678..ad09609227ff 100644
--- a/include/linux/if_packet.h
+++ b/include/linux/if_packet.h
@@ -42,6 +42,7 @@ struct sockaddr_ll
 #define PACKET_STATISTICS               6
 #define PACKET_COPY_THRESH              7
 #define PACKET_AUXDATA                  8
+#define PACKET_ORIGDEV                  9
 
 struct tpacket_stats
 {
diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c
index 36388b2f32f9..02e401cd683f 100644
--- a/net/packet/af_packet.c
+++ b/net/packet/af_packet.c
@@ -201,7 +201,8 @@ struct packet_sock {
         struct packet_type      prot_hook;
         spinlock_t              bind_lock;
         unsigned int            running:1,      /* prot_hook is attached*/
-                                auxdata:1;
+                                auxdata:1,
+                                origdev:1;
         int                     ifindex;        /* bound device         */
         __be16                  num;
 #ifdef CONFIG_PACKET_MULTICAST
@@ -528,7 +529,10 @@ static int packet_rcv(struct sk_buff *skb, struct net_device *dev, struct packet
         sll->sll_hatype = dev->type;
         sll->sll_protocol = skb->protocol;
         sll->sll_pkttype = skb->pkt_type;
-        sll->sll_ifindex = dev->ifindex;
+        if (unlikely(po->origdev) && skb->pkt_type == PACKET_HOST)
+                sll->sll_ifindex = orig_dev->ifindex;
+        else
+                sll->sll_ifindex = dev->ifindex;
         sll->sll_halen = 0;
 
         if (dev->hard_header_parse)
@@ -673,7 +677,10 @@ static int tpacket_rcv(struct sk_buff *skb, struct net_device *dev, struct packe
         sll->sll_hatype = dev->type;
         sll->sll_protocol = skb->protocol;
         sll->sll_pkttype = skb->pkt_type;
-        sll->sll_ifindex = dev->ifindex;
+        if (unlikely(po->origdev) && skb->pkt_type == PACKET_HOST)
+                sll->sll_ifindex = orig_dev->ifindex;
+        else
+                sll->sll_ifindex = dev->ifindex;
 
         h->tp_status = status;
         smp_mb();
@@ -1413,6 +1420,18 @@ packet_setsockopt(struct socket *sock, int level, int optname, char __user *optv
                 po->auxdata = !!val;
                 return 0;
         }
+        case PACKET_ORIGDEV:
+        {
+                int val;
+
+                if (optlen < sizeof(val))
+                        return -EINVAL;
+                if (copy_from_user(&val, optval, sizeof(val)))
+                        return -EFAULT;
+
+                po->origdev = !!val;
+                return 0;
+        }
         default:
                 return -ENOPROTOOPT;
         }
@@ -1456,6 +1475,13 @@ static int packet_getsockopt(struct socket *sock, int level, int optname,
 
                 data = &val;
                 break;
+        case PACKET_ORIGDEV:
+                if (len > sizeof(int))
+                        len = sizeof(int);
+                val = po->origdev;
+
+                data = &val;
+                break;
         default:
                 return -ENOPROTOOPT;
         }