tun: Allow GSO using virtio_net_hdr

Add a IFF_VNET_HDR flag.  This uses the same ABI as virtio_net
(ie. prepending struct virtio_net_hdr to packets) to indicate GSO and
checksum information.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Acked-by: Max Krasnyansky <maxk@qualcomm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/drivers/net/tun.c b/drivers/net/tun.c
index a314955e6994ca940e28d2c4bea02e8366bfbcae..aa4ee4439f048e864d559764c5f57316d1b6a7b3 100644 (file)
--- a/drivers/net/tun.c
+++ b/drivers/net/tun.c
@@ -63,6 +63,7 @@
 #include <linux/if_tun.h>
 #include <linux/crc32.h>
 #include <linux/nsproxy.h>
+#include <linux/virtio_net.h>
 #include <net/net_namespace.h>
 #include <net/netns/generic.h>
 
@@ -283,6 +284,7 @@ static __inline__ ssize_t tun_get_user(struct tun_struct *tun, struct iovec *iv,
        struct tun_pi pi = { 0, __constant_htons(ETH_P_IP) };
        struct sk_buff *skb;
        size_t len = count, align = 0;
+       struct virtio_net_hdr gso = { 0 };
 
        if (!(tun->flags & TUN_NO_PI)) {
                if ((len -= sizeof(pi)) > count)
@@ -292,6 +294,17 @@ static __inline__ ssize_t tun_get_user(struct tun_struct *tun, struct iovec *iv,
                        return -EFAULT;
        }
 
+       if (tun->flags & TUN_VNET_HDR) {
+               if ((len -= sizeof(gso)) > count)
+                       return -EINVAL;
+
+               if (memcpy_fromiovec((void *)&gso, iv, sizeof(gso)))
+                       return -EFAULT;
+
+               if (gso.hdr_len > len)
+                       return -EINVAL;
+       }
+
        if ((tun->flags & TUN_TYPE_MASK) == TUN_TAP_DEV) {
                align = NET_IP_ALIGN;
                if (unlikely(len < ETH_HLEN))
@@ -311,6 +324,16 @@ static __inline__ ssize_t tun_get_user(struct tun_struct *tun, struct iovec *iv,
                return -EFAULT;
        }
 
+       if (gso.flags & VIRTIO_NET_HDR_F_NEEDS_CSUM) {
+               if (!skb_partial_csum_set(skb, gso.csum_start,
+                                         gso.csum_offset)) {
+                       tun->dev->stats.rx_frame_errors++;
+                       kfree_skb(skb);
+                       return -EINVAL;
+               }
+       } else if (tun->flags & TUN_NOCHECKSUM)
+               skb->ip_summed = CHECKSUM_UNNECESSARY;
+
        switch (tun->flags & TUN_TYPE_MASK) {
        case TUN_TUN_DEV:
                if (tun->flags & TUN_NO_PI) {
@@ -337,8 +360,35 @@ static __inline__ ssize_t tun_get_user(struct tun_struct *tun, struct iovec *iv,
                break;
        };
 
-       if (tun->flags & TUN_NOCHECKSUM)
-               skb->ip_summed = CHECKSUM_UNNECESSARY;
+       if (gso.gso_type != VIRTIO_NET_HDR_GSO_NONE) {
+               pr_debug("GSO!\n");
+               switch (gso.gso_type & ~VIRTIO_NET_HDR_GSO_ECN) {
+               case VIRTIO_NET_HDR_GSO_TCPV4:
+                       skb_shinfo(skb)->gso_type = SKB_GSO_TCPV4;
+                       break;
+               case VIRTIO_NET_HDR_GSO_TCPV6:
+                       skb_shinfo(skb)->gso_type = SKB_GSO_TCPV6;
+                       break;
+               default:
+                       tun->dev->stats.rx_frame_errors++;
+                       kfree_skb(skb);
+                       return -EINVAL;
+               }
+
+               if (gso.gso_type & VIRTIO_NET_HDR_GSO_ECN)
+                       skb_shinfo(skb)->gso_type |= SKB_GSO_TCP_ECN;
+
+               skb_shinfo(skb)->gso_size = gso.gso_size;
+               if (skb_shinfo(skb)->gso_size == 0) {
+                       tun->dev->stats.rx_frame_errors++;
+                       kfree_skb(skb);
+                       return -EINVAL;
+               }
+
+               /* Header must be checked, and gso_segs computed. */
+               skb_shinfo(skb)->gso_type |= SKB_GSO_DODGY;
+               skb_shinfo(skb)->gso_segs = 0;
+       }
 
        netif_rx_ni(skb);
        tun->dev->last_rx = jiffies;
@@ -384,6 +434,39 @@ static __inline__ ssize_t tun_put_user(struct tun_struct *tun,
                total += sizeof(pi);
        }
 
+       if (tun->flags & TUN_VNET_HDR) {
+               struct virtio_net_hdr gso = { 0 }; /* no info leak */
+               if ((len -= sizeof(gso)) < 0)
+                       return -EINVAL;
+
+               if (skb_is_gso(skb)) {
+                       struct skb_shared_info *sinfo = skb_shinfo(skb);
+
+                       /* This is a hint as to how much should be linear. */
+                       gso.hdr_len = skb_headlen(skb);
+                       gso.gso_size = sinfo->gso_size;
+                       if (sinfo->gso_type & SKB_GSO_TCPV4)
+                               gso.gso_type = VIRTIO_NET_HDR_GSO_TCPV4;
+                       else if (sinfo->gso_type & SKB_GSO_TCPV6)
+                               gso.gso_type = VIRTIO_NET_HDR_GSO_TCPV6;
+                       else
+                               BUG();
+                       if (sinfo->gso_type & SKB_GSO_TCP_ECN)
+                               gso.gso_type |= VIRTIO_NET_HDR_GSO_ECN;
+               } else
+                       gso.gso_type = VIRTIO_NET_HDR_GSO_NONE;
+
+               if (skb->ip_summed == CHECKSUM_PARTIAL) {
+                       gso.flags = VIRTIO_NET_HDR_F_NEEDS_CSUM;
+                       gso.csum_start = skb->csum_start - skb_headroom(skb);
+                       gso.csum_offset = skb->csum_offset;
+               } /* else everything is zero */
+
+               if (unlikely(memcpy_toiovec(iv, (void *)&gso, sizeof(gso))))
+                       return -EFAULT;
+               total += sizeof(gso);
+       }
+
        len = min_t(int, skb->len, len);
 
        skb_copy_datagram_iovec(skb, 0, iv, len);
@@ -598,6 +681,11 @@ static int tun_set_iff(struct net *net, struct file *file, struct ifreq *ifr)
        else
                tun->flags &= ~TUN_ONE_QUEUE;
 
+       if (ifr->ifr_flags & IFF_VNET_HDR)
+               tun->flags |= TUN_VNET_HDR;
+       else
+               tun->flags &= ~TUN_VNET_HDR;
+
        file->private_data = tun;
        tun->attached = 1;
        get_net(dev_net(tun->dev));
@@ -684,7 +772,8 @@ static int tun_chr_ioctl(struct inode *inode, struct file *file,
                /* Currently this just means: "what IFF flags are valid?".
                 * This is needed because we never checked for invalid flags on
                 * TUNSETIFF. */
-               return put_user(IFF_TUN | IFF_TAP | IFF_NO_PI | IFF_ONE_QUEUE,
+               return put_user(IFF_TUN | IFF_TAP | IFF_NO_PI | IFF_ONE_QUEUE |
+                               IFF_VNET_HDR,
                                (unsigned int __user*)argp);
        }
 

diff --git a/include/linux/if_tun.h b/include/linux/if_tun.h
index 3f0a0995d4493e4f2f7aacf274374e8866e7cab6..563fae542da621c90017f623af2da3478030e2b5 100644 (file)
--- a/include/linux/if_tun.h
+++ b/include/linux/if_tun.h
@@ -31,6 +31,7 @@
 #define TUN_NO_PI      0x0040
 #define TUN_ONE_QUEUE  0x0080
 #define TUN_PERSIST    0x0100  
+#define TUN_VNET_HDR   0x0200
 
 /* Ioctl defines */
 #define TUNSETNOCSUM  _IOW('T', 200, int) 
@@ -48,6 +49,7 @@
 #define IFF_TAP                0x0002
 #define IFF_NO_PI      0x1000
 #define IFF_ONE_QUEUE  0x2000
+#define IFF_VNET_HDR   0x4000
 
 /* Features for GSO (TUNSETOFFLOAD). */
 #define TUN_F_CSUM     0x01    /* You can hand me unchecksummed packets. */