Re: [PATCH] AF_PACKET doesnt strip VLAN information
From: Willem de Bruijn <willemdebruijn.kernel@gmail.com>
Date: 2019-09-30 15:16:57
Also in:
lkml
On Mon, Sep 30, 2019 at 1:24 AM Sriram Krishnan [off-list ref] wrote:
When an application sends with AF_PACKET and places a vlan header on the raw packet; then the AF_PACKET needs to move the tag into the skb so that it gets processed normally through the rest of the transmit path. This is particularly a problem on Hyper-V where the host only allows vlan in the offload info.
This sounds like behavior that needs to be addressed in the driver, instead?
quoted hunk ↗ jump to hunk
Cc: xe-linux-external@cisco.com --- net/packet/af_packet.c | 26 ++++++++++++++++++++++++-- 1 file changed, 24 insertions(+), 2 deletions(-)diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c index e2742b0..cfe0904 100644 --- a/net/packet/af_packet.c +++ b/net/packet/af_packet.c@@ -1849,15 +1849,35 @@ static int packet_rcv_spkt(struct sk_buff *skb, struct net_device *dev, return 0; } -static void packet_parse_headers(struct sk_buff *skb, struct socket *sock) +static int packet_parse_headers(struct sk_buff *skb, struct socket *sock) { if ((!skb->protocol || skb->protocol == htons(ETH_P_ALL)) && sock->type == SOCK_RAW) {
If inside this branch, may miss packets with skb->protocol set to one of the VLAN Ethertypes.
+ __be16 ethertype;
+
skb_reset_mac_header(skb);
+
+ ethertype = eth_hdr(skb)->h_proto;
+ /*
+ * If Vlan tag is present in the packet
+ * move it to skb
+ */
+ if (eth_type_vlan(ethertype)) {
+ int err;
+ __be16 vlan_tci;
+
+ err = __skb_vlan_pop(skb, &vlan_tci);
+ if (unlikely(err))
+ return err;
+
+ __vlan_hwaccel_put_tag(skb, ethertype, vlan_tci);What happens with multiple tags (QinQ)?
quoted hunk ↗ jump to hunk
+ } + skb->protocol = dev_parse_header_protocol(skb); } skb_probe_transport_header(skb); + return 0; } /*@@ -1979,7 +1999,9 @@ static int packet_sendmsg_spkt(struct socket *sock, struct msghdr *msg, if (unlikely(extra_len == 4)) skb->no_fcs = 1; - packet_parse_headers(skb, sock); + err = packet_parse_headers(skb, sock); + if (err) + goto out_unlock;
This only tests the new return value in one of three callers of packet_sendmsg_spkt.