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Message-ID: <20230209080612-mutt-send-email-mst@kernel.org>
Date: Thu, 9 Feb 2023 08:07:09 -0500
From: "Michael S. Tsirkin" <mst@...hat.com>
To: 沈安琪(凛玥) <amy.saq@...group.com>
Cc: netdev@...r.kernel.org, willemdebruijn.kernel@...il.com,
davem@...emloft.net, jasowang@...hat.com,
谈鉴锋 <henry.tjf@...group.com>
Subject: Re: [PATCH 2/2] net/packet: send and receive pkt with given
vnet_hdr_sz
On Thu, Feb 09, 2023 at 08:43:15PM +0800, 沈安琪(凛玥) wrote:
> From: "Jianfeng Tan" <henry.tjf@...group.com>
>
> When raw socket is used as the backend for kernel vhost, currently it
> will regard the virtio net header as 10-byte, which is not always the
> case since some virtio features need virtio net header other than
> 10-byte, such as mrg_rxbuf and VERSION_1 that both need 12-byte virtio
> net header.
>
> Instead of hardcoding virtio net header length to 10 bytes, tpacket_snd,
> tpacket_rcv, packet_snd and packet_recvmsg now get the virtio net header
> size that is recorded in packet_sock to indicate the exact virtio net
> header size that virtio user actually prepares in the packets. By doing
> so, it can fix the issue of incorrect mac header parsing when these
> virtio features that need virtio net header other than 10-byte are
> enable.
>
> Signed-off-by: Jianfeng Tan <henry.tjf@...group.com>
> Co-developed-by: Anqi Shen <amy.saq@...group.com>
> Signed-off-by: Anqi Shen <amy.saq@...group.com>
Does it handle VERSION_1 though? That one is also LE.
Would it be better to pass a features bitmap instead?
> ---
> net/packet/af_packet.c | 48 +++++++++++++++++++++++++++++++++---------------
> 1 file changed, 33 insertions(+), 15 deletions(-)
>
> diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c
> index ab37baf..4f49939 100644
> --- a/net/packet/af_packet.c
> +++ b/net/packet/af_packet.c
> @@ -2092,18 +2092,25 @@ static unsigned int run_filter(struct sk_buff *skb,
> }
>
> static int packet_rcv_vnet(struct msghdr *msg, const struct sk_buff *skb,
> - size_t *len)
> + size_t *len, int vnet_hdr_sz)
> {
> struct virtio_net_hdr vnet_hdr;
> + int ret;
>
> - if (*len < sizeof(vnet_hdr))
> + if (*len < vnet_hdr_sz)
> return -EINVAL;
> - *len -= sizeof(vnet_hdr);
> + *len -= vnet_hdr_sz;
>
> if (virtio_net_hdr_from_skb(skb, &vnet_hdr, vio_le(), true, 0))
> return -EINVAL;
>
> - return memcpy_to_msg(msg, (void *)&vnet_hdr, sizeof(vnet_hdr));
> + ret = memcpy_to_msg(msg, (void *)&vnet_hdr, sizeof(vnet_hdr));
> +
> + /* reserve space for extra info in vnet_hdr if needed */
> + if (ret == 0)
> + iov_iter_advance(&msg->msg_iter, vnet_hdr_sz - sizeof(vnet_hdr));
> +
> + return ret;
> }
>
> /*
> @@ -2311,7 +2318,7 @@ static int tpacket_rcv(struct sk_buff *skb, struct net_device *dev,
> (maclen < 16 ? 16 : maclen)) +
> po->tp_reserve;
> if (po->has_vnet_hdr) {
> - netoff += sizeof(struct virtio_net_hdr);
> + netoff += po->vnet_hdr_sz;
> do_vnet = true;
> }
> macoff = netoff - maclen;
> @@ -2552,16 +2559,23 @@ static int __packet_snd_vnet_parse(struct virtio_net_hdr *vnet_hdr, size_t len)
> }
>
> static int packet_snd_vnet_parse(struct msghdr *msg, size_t *len,
> - struct virtio_net_hdr *vnet_hdr)
> + struct virtio_net_hdr *vnet_hdr, int vnet_hdr_sz)
> {
> - if (*len < sizeof(*vnet_hdr))
> + int ret;
> +
> + if (*len < vnet_hdr_sz)
> return -EINVAL;
> - *len -= sizeof(*vnet_hdr);
> + *len -= vnet_hdr_sz;
>
> if (!copy_from_iter_full(vnet_hdr, sizeof(*vnet_hdr), &msg->msg_iter))
> return -EFAULT;
>
> - return __packet_snd_vnet_parse(vnet_hdr, *len);
> + ret = __packet_snd_vnet_parse(vnet_hdr, *len);
> +
> + /* move iter to point to the start of mac header */
> + if (ret == 0)
> + iov_iter_advance(&msg->msg_iter, vnet_hdr_sz - sizeof(struct virtio_net_hdr));
> + return ret;
> }
>
> static int tpacket_fill_skb(struct packet_sock *po, struct sk_buff *skb,
> @@ -2730,6 +2744,7 @@ static int tpacket_snd(struct packet_sock *po, struct msghdr *msg)
> int status = TP_STATUS_AVAILABLE;
> int hlen, tlen, copylen = 0;
> long timeo = 0;
> + int vnet_hdr_sz;
>
> mutex_lock(&po->pg_vec_lock);
>
> @@ -2811,8 +2826,9 @@ static int tpacket_snd(struct packet_sock *po, struct msghdr *msg)
> tlen = dev->needed_tailroom;
> if (po->has_vnet_hdr) {
> vnet_hdr = data;
> - data += sizeof(*vnet_hdr);
> - tp_len -= sizeof(*vnet_hdr);
> + vnet_hdr_sz = po->vnet_hdr_sz;
> + data += vnet_hdr_sz;
> + tp_len -= vnet_hdr_sz;
> if (tp_len < 0 ||
> __packet_snd_vnet_parse(vnet_hdr, tp_len)) {
> tp_len = -EINVAL;
> @@ -2947,6 +2963,7 @@ static int packet_snd(struct socket *sock, struct msghdr *msg, size_t len)
> int offset = 0;
> struct packet_sock *po = pkt_sk(sk);
> bool has_vnet_hdr = false;
> + int vnet_hdr_sz;
> int hlen, tlen, linear;
> int extra_len = 0;
>
> @@ -2991,7 +3008,8 @@ static int packet_snd(struct socket *sock, struct msghdr *msg, size_t len)
> if (sock->type == SOCK_RAW)
> reserve = dev->hard_header_len;
> if (po->has_vnet_hdr) {
> - err = packet_snd_vnet_parse(msg, &len, &vnet_hdr);
> + vnet_hdr_sz = po->vnet_hdr_sz;
> + err = packet_snd_vnet_parse(msg, &len, &vnet_hdr, vnet_hdr_sz);
> if (err)
> goto out_unlock;
> has_vnet_hdr = true;
> @@ -3068,7 +3086,7 @@ static int packet_snd(struct socket *sock, struct msghdr *msg, size_t len)
> err = virtio_net_hdr_to_skb(skb, &vnet_hdr, vio_le());
> if (err)
> goto out_free;
> - len += sizeof(vnet_hdr);
> + len += vnet_hdr_sz;
> virtio_net_hdr_set_proto(skb, &vnet_hdr);
> }
>
> @@ -3452,10 +3470,10 @@ static int packet_recvmsg(struct socket *sock, struct msghdr *msg, size_t len,
> packet_rcv_try_clear_pressure(pkt_sk(sk));
>
> if (pkt_sk(sk)->has_vnet_hdr) {
> - err = packet_rcv_vnet(msg, skb, &len);
> + vnet_hdr_len = pkt_sk(sk)->vnet_hdr_sz;
> + err = packet_rcv_vnet(msg, skb, &len, vnet_hdr_len);
> if (err)
> goto out_free;
> - vnet_hdr_len = sizeof(struct virtio_net_hdr);
> }
>
> /* You lose any data beyond the buffer you gave. If it worries
> --
> 1.8.3.1
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