From e0ce4af920eb028f38bfd680b1d733f4c7a0b7cf Mon Sep 17 00:00:00 2001 From: Ian Campbell Date: Thu, 27 Jan 2011 04:14:03 +0000 Subject: [PATCH] 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 Cc: Jeremy Fitzhardinge Cc: David Miller Cc: xen-devel@lists.xensource.com Cc: netdev@vger.kernel.org Signed-off-by: David S. Miller --- drivers/net/xen-netfront.c | 96 ++++++++++++++++++++++++++++++++++---- 1 file changed, 88 insertions(+), 8 deletions(-) diff --git a/drivers/net/xen-netfront.c b/drivers/net/xen-netfront.c index 546de5749824..da1f12120346 100644 --- a/drivers/net/xen-netfront.c +++ b/drivers/net/xen-netfront.c @@ -120,6 +120,9 @@ struct netfront_info { unsigned long rx_pfn_array[NET_RX_RING_SIZE]; struct multicall_entry rx_mcl[NET_RX_RING_SIZE+1]; struct mmu_update rx_mmu[NET_RX_RING_SIZE]; + + /* Statistics */ + int rx_gso_checksum_fixup; }; struct netfront_rx_info { @@ -770,11 +773,29 @@ static RING_IDX xennet_fill_frags(struct netfront_info *np, return cons; } -static int skb_checksum_setup(struct sk_buff *skb) +static int checksum_setup(struct net_device *dev, struct sk_buff *skb) { struct iphdr *iph; unsigned char *th; int err = -EPROTO; + int recalculate_partial_csum = 0; + + /* + * A GSO SKB must be CHECKSUM_PARTIAL. However some buggy + * peers can fail to set NETRXF_csum_blank when sending a GSO + * frame. In this case force the SKB to CHECKSUM_PARTIAL and + * recalculate the partial checksum. + */ + if (skb->ip_summed != CHECKSUM_PARTIAL && skb_is_gso(skb)) { + struct netfront_info *np = netdev_priv(dev); + np->rx_gso_checksum_fixup++; + skb->ip_summed = CHECKSUM_PARTIAL; + recalculate_partial_csum = 1; + } + + /* A non-CHECKSUM_PARTIAL SKB does not require setup. */ + if (skb->ip_summed != CHECKSUM_PARTIAL) + return 0; if (skb->protocol != htons(ETH_P_IP)) goto out; @@ -788,9 +809,23 @@ static int skb_checksum_setup(struct sk_buff *skb) switch (iph->protocol) { case IPPROTO_TCP: skb->csum_offset = offsetof(struct tcphdr, check); + + if (recalculate_partial_csum) { + struct tcphdr *tcph = (struct tcphdr *)th; + tcph->check = ~csum_tcpudp_magic(iph->saddr, iph->daddr, + skb->len - iph->ihl*4, + IPPROTO_TCP, 0); + } break; case IPPROTO_UDP: skb->csum_offset = offsetof(struct udphdr, check); + + if (recalculate_partial_csum) { + struct udphdr *udph = (struct udphdr *)th; + udph->check = ~csum_tcpudp_magic(iph->saddr, iph->daddr, + skb->len - iph->ihl*4, + IPPROTO_UDP, 0); + } break; default: if (net_ratelimit()) @@ -829,13 +864,11 @@ static int handle_incoming_queue(struct net_device *dev, /* Ethernet work: Delayed to here as it peeks the header. */ skb->protocol = eth_type_trans(skb, dev); - if (skb->ip_summed == CHECKSUM_PARTIAL) { - if (skb_checksum_setup(skb)) { - kfree_skb(skb); - packets_dropped++; - dev->stats.rx_errors++; - continue; - } + if (checksum_setup(dev, skb)) { + kfree_skb(skb); + packets_dropped++; + dev->stats.rx_errors++; + continue; } dev->stats.rx_packets++; @@ -1632,12 +1665,59 @@ static void netback_changed(struct xenbus_device *dev, } } +static const struct xennet_stat { + char name[ETH_GSTRING_LEN]; + u16 offset; +} xennet_stats[] = { + { + "rx_gso_checksum_fixup", + offsetof(struct netfront_info, rx_gso_checksum_fixup) + }, +}; + +static int xennet_get_sset_count(struct net_device *dev, int string_set) +{ + switch (string_set) { + case ETH_SS_STATS: + return ARRAY_SIZE(xennet_stats); + default: + return -EINVAL; + } +} + +static void xennet_get_ethtool_stats(struct net_device *dev, + struct ethtool_stats *stats, u64 * data) +{ + void *np = netdev_priv(dev); + int i; + + for (i = 0; i < ARRAY_SIZE(xennet_stats); i++) + data[i] = *(int *)(np + xennet_stats[i].offset); +} + +static void xennet_get_strings(struct net_device *dev, u32 stringset, u8 * data) +{ + int i; + + switch (stringset) { + case ETH_SS_STATS: + for (i = 0; i < ARRAY_SIZE(xennet_stats); i++) + memcpy(data + i * ETH_GSTRING_LEN, + xennet_stats[i].name, ETH_GSTRING_LEN); + break; + } +} + static const struct ethtool_ops xennet_ethtool_ops = { .set_tx_csum = ethtool_op_set_tx_csum, .set_sg = xennet_set_sg, .set_tso = xennet_set_tso, .get_link = ethtool_op_get_link, + + .get_sset_count = xennet_get_sset_count, + .get_ethtool_stats = xennet_get_ethtool_stats, + .get_strings = xennet_get_strings, }; #ifdef CONFIG_SYSFS -- 2.34.1