packet: tpacket_snd gso and checksum offload

Support socket option PACKET_VNET_HDR together with PACKET_TX_RING.

When enabled, a struct virtio_net_hdr is expected to precede the data
in the ring. The vnet option must be set before the ring is created.

The implementation reuses the existing skb_copy_bits code that is used
when dev->hard_header_len is non-zero. Move this ll_header check to
before the skb alloc and combine it with a test for vnet_hdr->hdr_len.
Allocate and copy the max of the two.

Verified with test program at
github.com/wdebruij/kerneltools/blob/master/tests/psock_txring_vnet.c

Signed-off-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c
index 89377bf..b7e7851 100644 (file)
--- a/net/packet/af_packet.c
+++ b/net/packet/af_packet.c
@@ -2495,7 +2495,7 @@ static int packet_snd_vnet_gso(struct sk_buff *skb,
 
 static int tpacket_fill_skb(struct packet_sock *po, struct sk_buff *skb,
                void *frame, struct net_device *dev, void *data, int tp_len,
-               __be16 proto, unsigned char *addr, int hlen)
+               __be16 proto, unsigned char *addr, int hlen, int copylen)
 {
        union tpacket_uhdr ph;
        int to_write, offset, len, nr_frags, len_max;
@@ -2522,20 +2522,17 @@ static int tpacket_fill_skb(struct packet_sock *po, struct sk_buff *skb,
                                NULL, tp_len);
                if (unlikely(err < 0))
                        return -EINVAL;
-       } else if (dev->hard_header_len) {
-               if (ll_header_truncated(dev, tp_len))
-                       return -EINVAL;
-
+       } else if (copylen) {
                skb_push(skb, dev->hard_header_len);
-               err = skb_store_bits(skb, 0, data,
-                               dev->hard_header_len);
+               skb_put(skb, copylen - dev->hard_header_len);
+               err = skb_store_bits(skb, 0, data, copylen);
                if (unlikely(err))
                        return err;
                if (!skb->protocol)
                        tpacket_set_protocol(dev, skb);
 
-               data += dev->hard_header_len;
-               to_write -= dev->hard_header_len;
+               data += copylen;
+               to_write -= copylen;
        }
 
        offset = offset_in_page(data);
@@ -2631,6 +2628,7 @@ static int tpacket_snd(struct packet_sock *po, struct msghdr *msg)
 {
        struct sk_buff *skb;
        struct net_device *dev;
+       struct virtio_net_hdr *vnet_hdr = NULL;
        __be16 proto;
        int err, reserve = 0;
        void *ph;
@@ -2641,7 +2639,7 @@ static int tpacket_snd(struct packet_sock *po, struct msghdr *msg)
        void *data;
        int len_sum = 0;
        int status = TP_STATUS_AVAILABLE;
-       int hlen, tlen;
+       int hlen, tlen, copylen = 0;
 
        mutex_lock(&po->pg_vec_lock);
 
@@ -2674,7 +2672,7 @@ static int tpacket_snd(struct packet_sock *po, struct msghdr *msg)
        size_max = po->tx_ring.frame_size
                - (po->tp_hdrlen - sizeof(struct sockaddr_ll));
 
-       if (size_max > dev->mtu + reserve + VLAN_HLEN)
+       if ((size_max > dev->mtu + reserve + VLAN_HLEN) && !po->has_vnet_hdr)
                size_max = dev->mtu + reserve + VLAN_HLEN;
 
        do {
@@ -2694,8 +2692,28 @@ static int tpacket_snd(struct packet_sock *po, struct msghdr *msg)
                status = TP_STATUS_SEND_REQUEST;
                hlen = LL_RESERVED_SPACE(dev);
                tlen = dev->needed_tailroom;
+               if (po->has_vnet_hdr) {
+                       vnet_hdr = data;
+                       data += sizeof(*vnet_hdr);
+                       tp_len -= sizeof(*vnet_hdr);
+                       if (tp_len < 0 ||
+                           __packet_snd_vnet_parse(vnet_hdr, tp_len)) {
+                               tp_len = -EINVAL;
+                               goto tpacket_error;
+                       }
+                       copylen = __virtio16_to_cpu(vio_le(),
+                                                   vnet_hdr->hdr_len);
+               }
+               if (dev->hard_header_len) {
+                       if (ll_header_truncated(dev, tp_len)) {
+                               tp_len = -EINVAL;
+                               goto tpacket_error;
+                       }
+                       copylen = max_t(int, copylen, dev->hard_header_len);
+               }
                skb = sock_alloc_send_skb(&po->sk,
-                               hlen + tlen + sizeof(struct sockaddr_ll),
+                               hlen + tlen + sizeof(struct sockaddr_ll) +
+                               (copylen - dev->hard_header_len),
                                !need_wait, &err);
 
                if (unlikely(skb == NULL)) {
@@ -2705,9 +2723,10 @@ static int tpacket_snd(struct packet_sock *po, struct msghdr *msg)
                        goto out_status;
                }
                tp_len = tpacket_fill_skb(po, skb, ph, dev, data, tp_len, proto,
-                                         addr, hlen);
+                                         addr, hlen, copylen);
                if (likely(tp_len >= 0) &&
                    tp_len > dev->mtu + reserve &&
+                   !po->has_vnet_hdr &&
                    !packet_extra_vlan_len_allowed(dev, skb))
                        tp_len = -EMSGSIZE;
 
@@ -2726,6 +2745,11 @@ tpacket_error:
                        }
                }
 
+               if (po->has_vnet_hdr && packet_snd_vnet_gso(skb, vnet_hdr)) {
+                       tp_len = -EINVAL;
+                       goto tpacket_error;
+               }
+
                packet_pick_tx_queue(dev, skb);
 
                skb->destructor = tpacket_destruct_skb;
@@ -3616,9 +3640,6 @@ packet_setsockopt(struct socket *sock, int level, int optname, char __user *optv
                }
                if (optlen < len)
                        return -EINVAL;
-               if (pkt_sk(sk)->has_vnet_hdr &&
-                   optname == PACKET_TX_RING)
-                       return -EINVAL;
                if (copy_from_user(&req_u.req, optval, len))
                        return -EFAULT;
                return packet_set_ring(sk, &req_u, 0,