xen: netfront: handle incoming GSO SKBs which are not CHECKSUM_PARTIAL
The Linux network stack expects all GSO SKBs to have ip_summed == CHECKSUM_PARTIAL (which implies that the frame contains a partial checksum) and the Xen network ring protocol similarly expects an SKB which has GSO set to also have NETRX_csum_blank (which also implies a partial checksum). However there have been cases of buggy guests which mark a frame as GSO but do not set csum_blank. If we detect that we a receiving such a frame (which manifests as ip_summed != PARTIAL && skb_is_gso) then force the SKB to partial and recalculate the checksum, since we cannot rely on the peer having done so if they have not set csum_blank. Add an ethtool stat to track occurances of this event. Signed-off-by: Ian Campbell <ian.campbell@citrix.com> Cc: Jeremy Fitzhardinge <jeremy@goop.org> Cc: David Miller <davem@davemloft.net> Cc: xen-devel@lists.xensource.com Cc: netdev@vger.kernel.org Signed-off-by: David S. Miller <davem@davemloft.net>
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@ -120,6 +120,9 @@ struct netfront_info {
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unsigned long rx_pfn_array[NET_RX_RING_SIZE];
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struct multicall_entry rx_mcl[NET_RX_RING_SIZE+1];
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struct mmu_update rx_mmu[NET_RX_RING_SIZE];
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/* Statistics */
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int rx_gso_checksum_fixup;
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};
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struct netfront_rx_info {
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@ -770,11 +773,29 @@ static RING_IDX xennet_fill_frags(struct netfront_info *np,
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return cons;
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}
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static int skb_checksum_setup(struct sk_buff *skb)
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static int checksum_setup(struct net_device *dev, struct sk_buff *skb)
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{
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struct iphdr *iph;
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unsigned char *th;
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int err = -EPROTO;
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int recalculate_partial_csum = 0;
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/*
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* A GSO SKB must be CHECKSUM_PARTIAL. However some buggy
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* peers can fail to set NETRXF_csum_blank when sending a GSO
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* frame. In this case force the SKB to CHECKSUM_PARTIAL and
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* recalculate the partial checksum.
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*/
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if (skb->ip_summed != CHECKSUM_PARTIAL && skb_is_gso(skb)) {
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struct netfront_info *np = netdev_priv(dev);
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np->rx_gso_checksum_fixup++;
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skb->ip_summed = CHECKSUM_PARTIAL;
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recalculate_partial_csum = 1;
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}
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/* A non-CHECKSUM_PARTIAL SKB does not require setup. */
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if (skb->ip_summed != CHECKSUM_PARTIAL)
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return 0;
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if (skb->protocol != htons(ETH_P_IP))
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goto out;
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@ -788,9 +809,23 @@ static int skb_checksum_setup(struct sk_buff *skb)
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switch (iph->protocol) {
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case IPPROTO_TCP:
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skb->csum_offset = offsetof(struct tcphdr, check);
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if (recalculate_partial_csum) {
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struct tcphdr *tcph = (struct tcphdr *)th;
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tcph->check = ~csum_tcpudp_magic(iph->saddr, iph->daddr,
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skb->len - iph->ihl*4,
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IPPROTO_TCP, 0);
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}
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break;
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case IPPROTO_UDP:
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skb->csum_offset = offsetof(struct udphdr, check);
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if (recalculate_partial_csum) {
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struct udphdr *udph = (struct udphdr *)th;
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udph->check = ~csum_tcpudp_magic(iph->saddr, iph->daddr,
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skb->len - iph->ihl*4,
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IPPROTO_UDP, 0);
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}
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break;
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default:
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if (net_ratelimit())
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@ -829,13 +864,11 @@ static int handle_incoming_queue(struct net_device *dev,
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/* Ethernet work: Delayed to here as it peeks the header. */
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skb->protocol = eth_type_trans(skb, dev);
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if (skb->ip_summed == CHECKSUM_PARTIAL) {
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if (skb_checksum_setup(skb)) {
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kfree_skb(skb);
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packets_dropped++;
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dev->stats.rx_errors++;
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continue;
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}
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if (checksum_setup(dev, skb)) {
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kfree_skb(skb);
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packets_dropped++;
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dev->stats.rx_errors++;
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continue;
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}
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dev->stats.rx_packets++;
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@ -1632,12 +1665,59 @@ static void netback_changed(struct xenbus_device *dev,
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}
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}
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static const struct xennet_stat {
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char name[ETH_GSTRING_LEN];
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u16 offset;
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} xennet_stats[] = {
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{
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"rx_gso_checksum_fixup",
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offsetof(struct netfront_info, rx_gso_checksum_fixup)
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},
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};
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static int xennet_get_sset_count(struct net_device *dev, int string_set)
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{
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switch (string_set) {
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case ETH_SS_STATS:
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return ARRAY_SIZE(xennet_stats);
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default:
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return -EINVAL;
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}
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}
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static void xennet_get_ethtool_stats(struct net_device *dev,
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struct ethtool_stats *stats, u64 * data)
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{
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void *np = netdev_priv(dev);
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int i;
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for (i = 0; i < ARRAY_SIZE(xennet_stats); i++)
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data[i] = *(int *)(np + xennet_stats[i].offset);
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}
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static void xennet_get_strings(struct net_device *dev, u32 stringset, u8 * data)
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{
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int i;
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switch (stringset) {
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case ETH_SS_STATS:
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for (i = 0; i < ARRAY_SIZE(xennet_stats); i++)
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memcpy(data + i * ETH_GSTRING_LEN,
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xennet_stats[i].name, ETH_GSTRING_LEN);
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break;
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}
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}
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static const struct ethtool_ops xennet_ethtool_ops =
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{
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.set_tx_csum = ethtool_op_set_tx_csum,
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.set_sg = xennet_set_sg,
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.set_tso = xennet_set_tso,
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.get_link = ethtool_op_get_link,
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.get_sset_count = xennet_get_sset_count,
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.get_ethtool_stats = xennet_get_ethtool_stats,
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.get_strings = xennet_get_strings,
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};
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#ifdef CONFIG_SYSFS
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