From 104ba78c98808ae837d1f63aae58c183db5505df Mon Sep 17 00:00:00 2001 From: Willem de Bruijn Date: Wed, 26 Oct 2016 11:23:07 -0400 Subject: [PATCH] packet: on direct_xmit, limit tso and csum to supported devices When transmitting on a packet socket with PACKET_VNET_HDR and PACKET_QDISC_BYPASS, validate device support for features requested in vnet_hdr. Drop TSO packets sent to devices that do not support TSO or have the feature disabled. Note that the latter currently do process those packets correctly, regardless of not advertising the feature. Because of SKB_GSO_DODGY, it is not sufficient to test device features with netif_needs_gso. Full validate_xmit_skb is needed. Switch to software checksum for non-TSO packets that request checksum offload if that device feature is unsupported or disabled. Note that similar to the TSO case, device drivers may perform checksum offload correctly even when not advertising it. When switching to software checksum, packets hit skb_checksum_help, which has two BUG_ON checksum not in linear segment. Packet sockets always allocate at least up to csum_start + csum_off + 2 as linear. Tested by running github.com/wdebruij/kerneltools/psock_txring_vnet.c ethtool -K eth0 tso off tx on psock_txring_vnet -d $dst -s $src -i eth0 -l 2000 -n 1 -q -v psock_txring_vnet -d $dst -s $src -i eth0 -l 2000 -n 1 -q -v -N ethtool -K eth0 tx off psock_txring_vnet -d $dst -s $src -i eth0 -l 1000 -n 1 -q -v -G psock_txring_vnet -d $dst -s $src -i eth0 -l 1000 -n 1 -q -v -G -N v2: - add EXPORT_SYMBOL_GPL(validate_xmit_skb_list) Fixes: d346a3fae3ff ("packet: introduce PACKET_QDISC_BYPASS socket option") Signed-off-by: Willem de Bruijn Acked-by: Eric Dumazet Acked-by: Daniel Borkmann Signed-off-by: David S. Miller --- net/core/dev.c | 1 + net/packet/af_packet.c | 9 ++++----- 2 files changed, 5 insertions(+), 5 deletions(-) diff --git a/net/core/dev.c b/net/core/dev.c index dbc871306910..f745112f7efa 100644 --- a/net/core/dev.c +++ b/net/core/dev.c @@ -3035,6 +3035,7 @@ struct sk_buff *validate_xmit_skb_list(struct sk_buff *skb, struct net_device *d } return head; } +EXPORT_SYMBOL_GPL(validate_xmit_skb_list); static void qdisc_pkt_len_init(struct sk_buff *skb) { diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c index 11db0d619c00..d2238b204691 100644 --- a/net/packet/af_packet.c +++ b/net/packet/af_packet.c @@ -250,7 +250,7 @@ static void __fanout_link(struct sock *sk, struct packet_sock *po); static int packet_direct_xmit(struct sk_buff *skb) { struct net_device *dev = skb->dev; - netdev_features_t features; + struct sk_buff *orig_skb = skb; struct netdev_queue *txq; int ret = NETDEV_TX_BUSY; @@ -258,9 +258,8 @@ static int packet_direct_xmit(struct sk_buff *skb) !netif_carrier_ok(dev))) goto drop; - features = netif_skb_features(skb); - if (skb_needs_linearize(skb, features) && - __skb_linearize(skb)) + skb = validate_xmit_skb_list(skb, dev); + if (skb != orig_skb) goto drop; txq = skb_get_tx_queue(dev, skb); @@ -280,7 +279,7 @@ static int packet_direct_xmit(struct sk_buff *skb) return ret; drop: atomic_long_inc(&dev->tx_dropped); - kfree_skb(skb); + kfree_skb_list(skb); return NET_XMIT_DROP; } -- 2.34.1