2 files changed, 27 insertions, 3 deletions

diff --git a/include/linux/if_packet.h b/include/linux/if_packet.h
index a630295b255f..18db0668065a 100644
--- a/include/linux/if_packet.h
+++ b/include/linux/if_packet.h
@@ -45,6 +45,7 @@ struct sockaddr_ll
 #define PACKET_ORIGDEV                  9
 #define PACKET_VERSION                  10
 #define PACKET_HDRLEN                   11
+#define PACKET_RESERVE                  12
 
 struct tpacket_stats
 {
diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c
index db792e02a37f..de73bcb5235a 100644
--- a/net/packet/af_packet.c
+++ b/net/packet/af_packet.c
@@ -188,6 +188,7 @@ struct packet_sock {
         unsigned int            pg_vec_len;
         enum tpacket_versions   tp_version;
         unsigned int            tp_hdrlen;
+        unsigned int            tp_reserve;
 #endif
 };
 
@@ -635,11 +636,13 @@ static int tpacket_rcv(struct sk_buff *skb, struct net_device *dev, struct packe
                 snaplen = res;
 
         if (sk->sk_type == SOCK_DGRAM) {
-                macoff = netoff = TPACKET_ALIGN(po->tp_hdrlen) + 16;
+                macoff = netoff = TPACKET_ALIGN(po->tp_hdrlen) + 16 +
+                                  po->tp_reserve;
         } else {
                 unsigned maclen = skb_network_offset(skb);
                 netoff = TPACKET_ALIGN(po->tp_hdrlen +
-                                       (maclen < 16 ? 16 : maclen));
+                                       (maclen < 16 ? 16 : maclen)) +
+                        po->tp_reserve;
                 macoff = netoff - maclen;
         }
 
@@ -1448,6 +1451,19 @@ packet_setsockopt(struct socket *sock, int level, int optname, char __user *optv
                         return -EINVAL;
                 }
         }
+        case PACKET_RESERVE:
+        {
+                unsigned int val;
+
+                if (optlen != sizeof(val))
+                        return -EINVAL;
+                if (po->pg_vec)
+                        return -EBUSY;
+                if (copy_from_user(&val, optval, sizeof(val)))
+                        return -EFAULT;
+                po->tp_reserve = val;
+                return 0;
+        }
 #endif
         case PACKET_AUXDATA:
         {
@@ -1547,6 +1563,12 @@ static int packet_getsockopt(struct socket *sock, int level, int optname,
                 }
                 data = &val;
                 break;
+        case PACKET_RESERVE:
+                if (len > sizeof(unsigned int))
+                        len = sizeof(unsigned int);
+                val = po->tp_reserve;
+                data = &val;
+                break;
 #endif
         default:
                 return -ENOPROTOOPT;
@@ -1790,7 +1812,8 @@ static int packet_set_ring(struct sock *sk, struct tpacket_req *req, int closing
                         return -EINVAL;
                 if (unlikely(req->tp_block_size & (PAGE_SIZE - 1)))
                         return -EINVAL;
-                if (unlikely(req->tp_frame_size < po->tp_hdrlen))
+                if (unlikely(req->tp_frame_size < po->tp_hdrlen +
+                                                  po->tp_reserve))
                         return -EINVAL;
                 if (unlikely(req->tp_frame_size & (TPACKET_ALIGNMENT - 1)))
                         return -EINVAL;