Merge branch 'ufo-fix'

Ben Hutchings says:

====================
drivers/net,ipv6: Fix IPv6 fragment ID selection for virtio

The virtio net protocol supports UFO but does not provide for passing a
fragment ID for fragmentation of IPv6 packets.  We used to generate a
fragment ID wherever such a packet was fragmented, but currently we
always use ID=0!

v2: Add blank lines after declarations
====================

Signed-off-by: David S. Miller <davem@davemloft.net>

5 files changed, 74 insertions, 27 deletions

diff --git a/drivers/net/macvtap.c b/drivers/net/macvtap.c
index 65e2892342bd..6f226de655a4 100644
--- a/drivers/net/macvtap.c
+++ b/drivers/net/macvtap.c
@@ -16,6 +16,7 @@
 #include <linux/idr.h>
 #include <linux/fs.h>
 
+#include <net/ipv6.h>
 #include <net/net_namespace.h>
 #include <net/rtnetlink.h>
 #include <net/sock.h>
@@ -65,7 +66,7 @@ static struct cdev macvtap_cdev;
 static const struct proto_ops macvtap_socket_ops;
 
 #define TUN_OFFLOADS (NETIF_F_HW_CSUM | NETIF_F_TSO_ECN | NETIF_F_TSO | \
-                      NETIF_F_TSO6 | NETIF_F_UFO)
+                      NETIF_F_TSO6)
 #define RX_OFFLOADS (NETIF_F_GRO | NETIF_F_LRO)
 #define TAP_FEATURES (NETIF_F_GSO | NETIF_F_SG)
 
@@ -569,7 +570,11 @@ static int macvtap_skb_from_vnet_hdr(struct sk_buff *skb,
                         gso_type = SKB_GSO_TCPV6;
                         break;
                 case VIRTIO_NET_HDR_GSO_UDP:
+                        pr_warn_once("macvtap: %s: using disabled UFO feature; please fix this program\n",
+                                     current->comm);
                         gso_type = SKB_GSO_UDP;
+                        if (skb->protocol == htons(ETH_P_IPV6))
+                                ipv6_proxy_select_ident(skb);
                         break;
                 default:
                         return -EINVAL;
@@ -614,8 +619,6 @@ static void macvtap_skb_to_vnet_hdr(const struct sk_buff *skb,
                         vnet_hdr->gso_type = VIRTIO_NET_HDR_GSO_TCPV4;
                 else if (sinfo->gso_type & SKB_GSO_TCPV6)
                         vnet_hdr->gso_type = VIRTIO_NET_HDR_GSO_TCPV6;
-                else if (sinfo->gso_type & SKB_GSO_UDP)
-                        vnet_hdr->gso_type = VIRTIO_NET_HDR_GSO_UDP;
                 else
                         BUG();
                 if (sinfo->gso_type & SKB_GSO_TCP_ECN)
@@ -950,9 +953,6 @@ static int set_offload(struct macvtap_queue *q, unsigned long arg)
                         if (arg & TUN_F_TSO6)
                                 feature_mask |= NETIF_F_TSO6;
                 }
-
-                if (arg & TUN_F_UFO)
-                        feature_mask |= NETIF_F_UFO;
         }
 
         /* tun/tap driver inverts the usage for TSO offloads, where
@@ -963,7 +963,7 @@ static int set_offload(struct macvtap_queue *q, unsigned long arg)
          * When user space turns off TSO, we turn off GSO/LRO so that
          * user-space will not receive TSO frames.
          */
-        if (feature_mask & (NETIF_F_TSO | NETIF_F_TSO6 | NETIF_F_UFO))
+        if (feature_mask & (NETIF_F_TSO | NETIF_F_TSO6))
                 features |= RX_OFFLOADS;
         else
                 features &= ~RX_OFFLOADS;
@@ -1064,7 +1064,7 @@ static long macvtap_ioctl(struct file *file, unsigned int cmd,
         case TUNSETOFFLOAD:
                 /* let the user check for future flags */
                 if (arg & ~(TUN_F_CSUM | TUN_F_TSO4 | TUN_F_TSO6 |
-                            TUN_F_TSO_ECN | TUN_F_UFO))
+                            TUN_F_TSO_ECN))
                         return -EINVAL;
 
                 rtnl_lock();
diff --git a/drivers/net/tun.c b/drivers/net/tun.c
index 186ce541c657..7302398f0b1f 100644
--- a/drivers/net/tun.c
+++ b/drivers/net/tun.c
@@ -65,6 +65,7 @@
 #include <linux/nsproxy.h>
 #include <linux/virtio_net.h>
 #include <linux/rcupdate.h>
+#include <net/ipv6.h>
 #include <net/net_namespace.h>
 #include <net/netns/generic.h>
 #include <net/rtnetlink.h>
@@ -174,7 +175,7 @@ struct tun_struct {
         struct net_device       *dev;
         netdev_features_t       set_features;
 #define TUN_USER_FEATURES (NETIF_F_HW_CSUM|NETIF_F_TSO_ECN|NETIF_F_TSO| \
-                          NETIF_F_TSO6|NETIF_F_UFO)
+                          NETIF_F_TSO6)
 
         int                     vnet_hdr_sz;
         int                     sndbuf;
@@ -1139,6 +1140,8 @@ static ssize_t tun_get_user(struct tun_struct *tun, struct tun_file *tfile,
                 break;
         }
 
+        skb_reset_network_header(skb);
+
         if (gso.gso_type != VIRTIO_NET_HDR_GSO_NONE) {
                 pr_debug("GSO!\n");
                 switch (gso.gso_type & ~VIRTIO_NET_HDR_GSO_ECN) {
@@ -1149,8 +1152,20 @@ static ssize_t tun_get_user(struct tun_struct *tun, struct tun_file *tfile,
                         skb_shinfo(skb)->gso_type = SKB_GSO_TCPV6;
                         break;
                 case VIRTIO_NET_HDR_GSO_UDP:
+                {
+                        static bool warned;
+
+                        if (!warned) {
+                                warned = true;
+                                netdev_warn(tun->dev,
+                                            "%s: using disabled UFO feature; please fix this program\n",
+                                            current->comm);
+                        }
                         skb_shinfo(skb)->gso_type = SKB_GSO_UDP;
+                        if (skb->protocol == htons(ETH_P_IPV6))
+                                ipv6_proxy_select_ident(skb);
                         break;
+                }
                 default:
                         tun->dev->stats.rx_frame_errors++;
                         kfree_skb(skb);
@@ -1179,7 +1194,6 @@ static ssize_t tun_get_user(struct tun_struct *tun, struct tun_file *tfile,
                 skb_shinfo(skb)->tx_flags |= SKBTX_SHARED_FRAG;
         }
 
-        skb_reset_network_header(skb);
         skb_probe_transport_header(skb, 0);
 
         rxhash = skb_get_hash(skb);
@@ -1251,8 +1265,6 @@ static ssize_t tun_put_user(struct tun_struct *tun,
                                 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 if (sinfo->gso_type & SKB_GSO_UDP)
-                                gso.gso_type = VIRTIO_NET_HDR_GSO_UDP;
                         else {
                                 pr_err("unexpected GSO type: "
                                        "0x%x, gso_size %d, hdr_len %d\n",
@@ -1762,11 +1774,6 @@ static int set_offload(struct tun_struct *tun, unsigned long arg)
                                 features |= NETIF_F_TSO6;
                         arg &= ~(TUN_F_TSO4|TUN_F_TSO6);
                 }
-
-                if (arg & TUN_F_UFO) {
-                        features |= NETIF_F_UFO;
-                        arg &= ~TUN_F_UFO;
-                }
         }
 
         /* This gives the user a way to test for new features in future by
diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index d75256bd1a6a..ec2a8b41ed41 100644
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -491,8 +491,17 @@ static void receive_buf(struct receive_queue *rq, void *buf, unsigned int len)
                         skb_shinfo(skb)->gso_type = SKB_GSO_TCPV4;
                         break;
                 case VIRTIO_NET_HDR_GSO_UDP:
+                {
+                        static bool warned;
+
+                        if (!warned) {
+                                warned = true;
+                                netdev_warn(dev,
+                                            "host using disabled UFO feature; please fix it\n");
+                        }
                         skb_shinfo(skb)->gso_type = SKB_GSO_UDP;
                         break;
+                }
                 case VIRTIO_NET_HDR_GSO_TCPV6:
                         skb_shinfo(skb)->gso_type = SKB_GSO_TCPV6;
                         break;
@@ -881,8 +890,6 @@ static int xmit_skb(struct send_queue *sq, struct sk_buff *skb)
                         hdr->hdr.gso_type = VIRTIO_NET_HDR_GSO_TCPV4;
                 else if (skb_shinfo(skb)->gso_type & SKB_GSO_TCPV6)
                         hdr->hdr.gso_type = VIRTIO_NET_HDR_GSO_TCPV6;
-                else if (skb_shinfo(skb)->gso_type & SKB_GSO_UDP)
-                        hdr->hdr.gso_type = VIRTIO_NET_HDR_GSO_UDP;
                 else
                         BUG();
                 if (skb_shinfo(skb)->gso_type & SKB_GSO_TCP_ECN)
@@ -1705,7 +1712,7 @@ static int virtnet_probe(struct virtio_device *vdev)
                         dev->features |= NETIF_F_HW_CSUM|NETIF_F_SG|NETIF_F_FRAGLIST;
 
                 if (virtio_has_feature(vdev, VIRTIO_NET_F_GSO)) {
-                        dev->hw_features |= NETIF_F_TSO | NETIF_F_UFO
+                        dev->hw_features |= NETIF_F_TSO
                                 | NETIF_F_TSO_ECN | NETIF_F_TSO6;
                 }
                 /* Individual feature bits: what can host handle? */
@@ -1715,11 +1722,9 @@ static int virtnet_probe(struct virtio_device *vdev)
                         dev->hw_features |= NETIF_F_TSO6;
                 if (virtio_has_feature(vdev, VIRTIO_NET_F_HOST_ECN))
                         dev->hw_features |= NETIF_F_TSO_ECN;
-                if (virtio_has_feature(vdev, VIRTIO_NET_F_HOST_UFO))
-                        dev->hw_features |= NETIF_F_UFO;
 
                 if (gso)
-                        dev->features |= dev->hw_features & (NETIF_F_ALL_TSO|NETIF_F_UFO);
+                        dev->features |= dev->hw_features & NETIF_F_ALL_TSO;
                 /* (!csum && gso) case will be fixed by register_netdev() */
         }
         if (virtio_has_feature(vdev, VIRTIO_NET_F_GUEST_CSUM))
@@ -1757,8 +1762,7 @@ static int virtnet_probe(struct virtio_device *vdev)
         /* If we can receive ANY GSO packets, we must allocate large ones. */
         if (virtio_has_feature(vdev, VIRTIO_NET_F_GUEST_TSO4) ||
             virtio_has_feature(vdev, VIRTIO_NET_F_GUEST_TSO6) ||
-            virtio_has_feature(vdev, VIRTIO_NET_F_GUEST_ECN) ||
-            virtio_has_feature(vdev, VIRTIO_NET_F_GUEST_UFO))
+            virtio_has_feature(vdev, VIRTIO_NET_F_GUEST_ECN))
                 vi->big_packets = true;
 
         if (virtio_has_feature(vdev, VIRTIO_NET_F_MRG_RXBUF))
@@ -1952,9 +1956,9 @@ static struct virtio_device_id id_table[] = {
 static unsigned int features[] = {
         VIRTIO_NET_F_CSUM, VIRTIO_NET_F_GUEST_CSUM,
         VIRTIO_NET_F_GSO, VIRTIO_NET_F_MAC,
-        VIRTIO_NET_F_HOST_TSO4, VIRTIO_NET_F_HOST_UFO, VIRTIO_NET_F_HOST_TSO6,
+        VIRTIO_NET_F_HOST_TSO4, VIRTIO_NET_F_HOST_TSO6,
         VIRTIO_NET_F_HOST_ECN, VIRTIO_NET_F_GUEST_TSO4, VIRTIO_NET_F_GUEST_TSO6,
-        VIRTIO_NET_F_GUEST_ECN, VIRTIO_NET_F_GUEST_UFO,
+        VIRTIO_NET_F_GUEST_ECN,
         VIRTIO_NET_F_MRG_RXBUF, VIRTIO_NET_F_STATUS, VIRTIO_NET_F_CTRL_VQ,
         VIRTIO_NET_F_CTRL_RX, VIRTIO_NET_F_CTRL_VLAN,
         VIRTIO_NET_F_GUEST_ANNOUNCE, VIRTIO_NET_F_MQ,
diff --git a/include/net/ipv6.h b/include/net/ipv6.h
index 97f472012438..4292929392b0 100644
--- a/include/net/ipv6.h
+++ b/include/net/ipv6.h
@@ -671,6 +671,8 @@ static inline int ipv6_addr_diff(const struct in6_addr *a1, const struct in6_add
         return __ipv6_addr_diff(a1, a2, sizeof(struct in6_addr));
 }
 
+void ipv6_proxy_select_ident(struct sk_buff *skb);
+
 int ip6_dst_hoplimit(struct dst_entry *dst);
 
 static inline int ip6_sk_dst_hoplimit(struct ipv6_pinfo *np, struct flowi6 *fl6,
diff --git a/net/ipv6/output_core.c b/net/ipv6/output_core.c
index fc24c390af05..97f41a3e68d9 100644
--- a/net/ipv6/output_core.c
+++ b/net/ipv6/output_core.c
@@ -3,11 +3,45 @@
  * not configured or static.  These functions are needed by GSO/GRO implementation.
  */
 #include <linux/export.h>
+#include <net/ip.h>
 #include <net/ipv6.h>
 #include <net/ip6_fib.h>
 #include <net/addrconf.h>
 #include <net/secure_seq.h>
 
+/* This function exists only for tap drivers that must support broken
+ * clients requesting UFO without specifying an IPv6 fragment ID.
+ *
+ * This is similar to ipv6_select_ident() but we use an independent hash
+ * seed to limit information leakage.
+ *
+ * The network header must be set before calling this.
+ */
+void ipv6_proxy_select_ident(struct sk_buff *skb)
+{
+        static u32 ip6_proxy_idents_hashrnd __read_mostly;
+        struct in6_addr buf[2];
+        struct in6_addr *addrs;
+        u32 hash, id;
+
+        addrs = skb_header_pointer(skb,
+                                   skb_network_offset(skb) +
+                                   offsetof(struct ipv6hdr, saddr),
+                                   sizeof(buf), buf);
+        if (!addrs)
+                return;
+
+        net_get_random_once(&ip6_proxy_idents_hashrnd,
+                            sizeof(ip6_proxy_idents_hashrnd));
+
+        hash = __ipv6_addr_jhash(&addrs[1], ip6_proxy_idents_hashrnd);
+        hash = __ipv6_addr_jhash(&addrs[0], hash);
+
+        id = ip_idents_reserve(hash, 1);
+        skb_shinfo(skb)->ip6_frag_id = htonl(id);
+}
+EXPORT_SYMBOL_GPL(ipv6_proxy_select_ident);
+
 int ip6_find_1stfragopt(struct sk_buff *skb, u8 **nexthdr)
 {
         u16 offset = sizeof(struct ipv6hdr);