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Tsirkin" To: =?utf-8?B?5rKI5a6J55CqKOWHm+eOpSk=?= Cc: netdev@vger.kernel.org, willemdebruijn.kernel@gmail.com, davem@davemloft.net, jasowang@redhat.com, =?utf-8?B?6LCI6Ym06ZSL?= Subject: Re: [PATCH 2/2] net/packet: send and receive pkt with given vnet_hdr_sz Message-ID: <20230209080612-mutt-send-email-mst@kernel.org> References: <1675946595-103034-1-git-send-email-amy.saq@antgroup.com> <1675946595-103034-3-git-send-email-amy.saq@antgroup.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <1675946595-103034-3-git-send-email-amy.saq@antgroup.com> Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On Thu, Feb 09, 2023 at 08:43:15PM +0800, 沈安琪(凛玥) wrote: > From: "Jianfeng Tan" > > 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 > Co-developed-by: Anqi Shen > Signed-off-by: Anqi Shen 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