On Sun, Sep 15, 2024 at 9:07 AM Akihiko Odaki <akihiko.od...@daynix.com> wrote:
>
> receive_header() used to cast the const qualifier of the pointer to the
> received packet away to modify the header. Avoid this by copying the
> received header to buffer.
>
> Signed-off-by: Akihiko Odaki <akihiko.od...@daynix.com>
> ---
> hw/net/virtio-net.c | 85
> +++++++++++++++++++++++++++++------------------------
> 1 file changed, 46 insertions(+), 39 deletions(-)
>
> diff --git a/hw/net/virtio-net.c b/hw/net/virtio-net.c
> index 3fc1d10cb9e0..ca4e22344f78 100644
> --- a/hw/net/virtio-net.c
> +++ b/hw/net/virtio-net.c
> @@ -1685,41 +1685,44 @@ static void virtio_net_hdr_swap(VirtIODevice *vdev,
> struct virtio_net_hdr *hdr)
> * cache.
> */
> static void work_around_broken_dhclient(struct virtio_net_hdr *hdr,
> - uint8_t *buf, size_t size)
> + size_t *hdr_len, const uint8_t *buf,
> + size_t buf_size, size_t *buf_offset)
> {
> size_t csum_size = ETH_HLEN + sizeof(struct ip_header) +
> sizeof(struct udp_header);
>
> + buf += *buf_offset;
> + buf_size -= *buf_offset;
> +
> if ((hdr->flags & VIRTIO_NET_HDR_F_NEEDS_CSUM) && /* missing csum */
> - (size >= csum_size && size < 1500) && /* normal sized MTU */
> + (buf_size >= csum_size && buf_size < 1500) && /* normal sized MTU */
> (buf[12] == 0x08 && buf[13] == 0x00) && /* ethertype == IPv4 */
> (buf[23] == 17) && /* ip.protocol == UDP */
> (buf[34] == 0 && buf[35] == 67)) { /* udp.srcport == bootps */
> - net_checksum_calculate(buf, size, CSUM_UDP);
> + memcpy((uint8_t *)hdr + *hdr_len, buf, csum_size);
> + net_checksum_calculate((uint8_t *)hdr + *hdr_len, csum_size,
> CSUM_UDP);
> hdr->flags &= ~VIRTIO_NET_HDR_F_NEEDS_CSUM;
> + *hdr_len += csum_size;
> + *buf_offset += csum_size;
> }
> }
>
> -static void receive_header(VirtIONet *n, const struct iovec *iov, int
> iov_cnt,
> - const void *buf, size_t size)
> +static size_t receive_header(VirtIONet *n, struct virtio_net_hdr *hdr,
> + const void *buf, size_t buf_size,
> + size_t *buf_offset)
> {
> - if (n->has_vnet_hdr) {
> - /* FIXME this cast is evil */
> - void *wbuf = (void *)buf;
> - work_around_broken_dhclient(wbuf, wbuf + n->host_hdr_len,
> - size - n->host_hdr_len);
> + size_t hdr_len = n->guest_hdr_len;
>
> - if (n->needs_vnet_hdr_swap) {
> - virtio_net_hdr_swap(VIRTIO_DEVICE(n), wbuf);
> - }
> - iov_from_buf(iov, iov_cnt, 0, buf, sizeof(struct virtio_net_hdr));
> - } else {
> - struct virtio_net_hdr hdr = {
> - .flags = 0,
> - .gso_type = VIRTIO_NET_HDR_GSO_NONE
> - };
> - iov_from_buf(iov, iov_cnt, 0, &hdr, sizeof hdr);
> + memcpy(hdr, buf, sizeof(struct virtio_net_hdr));
> +
> + *buf_offset = n->host_hdr_len;
> + work_around_broken_dhclient(hdr, &hdr_len, buf, buf_size, buf_offset);
> +
> + if (n->needs_vnet_hdr_swap) {
> + virtio_net_hdr_swap(VIRTIO_DEVICE(n), hdr);
> }
> +
> + return hdr_len;
> }
>
> static int receive_filter(VirtIONet *n, const uint8_t *buf, int size)
> @@ -1887,6 +1890,13 @@ static int virtio_net_process_rss(NetClientState *nc,
> const uint8_t *buf,
> return (index == new_index) ? -1 : new_index;
> }
>
> +typedef struct Header {
> + struct virtio_net_hdr_v1_hash virtio_net;
> + struct eth_header eth;
> + struct ip_header ip;
> + struct udp_header udp;
> +} Header;
I don't see too much value in having this structure especially
considering eth/ip/udp is not even used.
Any reason we can simply use an array as a buffer in virtio_net_receive_rcu()?
Thanks
