1 files changed, 45 insertions, 1 deletions

diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c
index 9034f52659b5..f262dbfc7f06 100644
--- a/net/packet/af_packet.c
+++ b/net/packet/af_packet.c
@@ -1881,7 +1881,35 @@ static int tpacket_fill_skb(struct packet_sock *po, struct sk_buff *skb,
         skb_reserve(skb, hlen);
         skb_reset_network_header(skb);
 
-        data = ph.raw + po->tp_hdrlen - sizeof(struct sockaddr_ll);
+        if (po->tp_tx_has_off) {
+                int off_min, off_max, off;
+                off_min = po->tp_hdrlen - sizeof(struct sockaddr_ll);
+                off_max = po->tx_ring.frame_size - tp_len;
+                if (sock->type == SOCK_DGRAM) {
+                        switch (po->tp_version) {
+                        case TPACKET_V2:
+                                off = ph.h2->tp_net;
+                                break;
+                        default:
+                                off = ph.h1->tp_net;
+                                break;
+                        }
+                } else {
+                        switch (po->tp_version) {
+                        case TPACKET_V2:
+                                off = ph.h2->tp_mac;
+                                break;
+                        default:
+                                off = ph.h1->tp_mac;
+                                break;
+                        }
+                }
+                if (unlikely((off < off_min) || (off_max < off)))
+                        return -EINVAL;
+                data = ph.raw + off;
+        } else {
+                data = ph.raw + po->tp_hdrlen - sizeof(struct sockaddr_ll);
+        }
         to_write = tp_len;
 
         if (sock->type == SOCK_DGRAM) {
@@ -3109,6 +3137,19 @@ packet_setsockopt(struct socket *sock, int level, int optname, char __user *optv
 
                 return fanout_add(sk, val & 0xffff, val >> 16);
         }
+        case PACKET_TX_HAS_OFF:
+        {
+                unsigned int val;
+
+                if (optlen != sizeof(val))
+                        return -EINVAL;
+                if (po->rx_ring.pg_vec || po->tx_ring.pg_vec)
+                        return -EBUSY;
+                if (copy_from_user(&val, optval, sizeof(val)))
+                        return -EFAULT;
+                po->tp_tx_has_off = !!val;
+                return 0;
+        }
         default:
                 return -ENOPROTOOPT;
         }
@@ -3200,6 +3241,9 @@ static int packet_getsockopt(struct socket *sock, int level, int optname,
                         ((u32)po->fanout->type << 16)) :
                        0);
                 break;
+        case PACKET_TX_HAS_OFF:
+                val = po->tp_tx_has_off;
+                break;
         default:
                 return -ENOPROTOOPT;
         }