| Message ID | 20240915-queue-v1-6-b49bd49b926d@daynix.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | virtio-net fixes | expand |
On Sun, Sep 15, 2024 at 9:07 AM Akihiko Odaki <akihiko.odaki@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.odaki@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
On Mon, Oct 21, 2024 at 4:21 PM Jason Wang <jasowang@redhat.com> wrote: > > On Sun, Sep 15, 2024 at 9:07 AM Akihiko Odaki <akihiko.odaki@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.odaki@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()? Btw, since the code was for ancient guests and userspace, I wonder how it is tested. Thanks > > Thanks
On 2024/10/21 17:22, Jason Wang wrote: > On Mon, Oct 21, 2024 at 4:21 PM Jason Wang <jasowang@redhat.com> wrote: >> >> On Sun, Sep 15, 2024 at 9:07 AM Akihiko Odaki <akihiko.odaki@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.odaki@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()? We still need to access virtio_net and it needs to be properly aligned. We can still make the latter part an array, but it does not look nicer: typedef struct Header { struct virtio_net_hdr_v1_hash virtio_net; uint8_t eth[sizeof(struct eth_header) + sizeof(struct ip_header) + sizeof(struct udp_header)]; } Header; > > Btw, since the code was for ancient guests and userspace, I wonder how > it is tested. I didn't test with dhclient, but I tested with UDP packets synthesized with iperf. Regards, Akihiko Odaki
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; + static ssize_t virtio_net_receive_rcu(NetClientState *nc, const uint8_t *buf, size_t size) { @@ -1896,15 +1906,15 @@ static ssize_t virtio_net_receive_rcu(NetClientState *nc, const uint8_t *buf, VirtQueueElement *elems[VIRTQUEUE_MAX_SIZE]; size_t lens[VIRTQUEUE_MAX_SIZE]; struct iovec mhdr_sg[VIRTQUEUE_MAX_SIZE]; - struct virtio_net_hdr_v1_hash extra_hdr; + Header hdr; unsigned mhdr_cnt = 0; size_t offset, i, guest_offset, j; ssize_t err; - memset(&extra_hdr, 0, sizeof(extra_hdr)); + memset(&hdr.virtio_net, 0, sizeof(hdr.virtio_net)); if (n->rss_data.enabled && n->rss_data.enabled_software_rss) { - int index = virtio_net_process_rss(nc, buf, size, &extra_hdr); + int index = virtio_net_process_rss(nc, buf, size, &hdr.virtio_net); if (index >= 0) { nc = qemu_get_subqueue(n->nic, index); } @@ -1969,21 +1979,18 @@ static ssize_t virtio_net_receive_rcu(NetClientState *nc, const uint8_t *buf, if (n->mergeable_rx_bufs) { mhdr_cnt = iov_copy(mhdr_sg, ARRAY_SIZE(mhdr_sg), sg, elem->in_num, - offsetof(typeof(extra_hdr), hdr.num_buffers), - sizeof(extra_hdr.hdr.num_buffers)); + offsetof(typeof(hdr), + virtio_net.hdr.num_buffers), + sizeof(hdr.virtio_net.hdr.num_buffers)); } - receive_header(n, sg, elem->in_num, buf, size); - if (n->rss_data.populate_hash) { - offset = offsetof(typeof(extra_hdr), hash_value); - iov_from_buf(sg, elem->in_num, offset, - (char *)&extra_hdr + offset, - sizeof(extra_hdr.hash_value) + - sizeof(extra_hdr.hash_report)); - } - offset = n->host_hdr_len; - total += n->guest_hdr_len; - guest_offset = n->guest_hdr_len; + guest_offset = n->has_vnet_hdr ? + receive_header(n, (struct virtio_net_hdr *)&hdr, + buf, size, &offset) : + n->guest_hdr_len; + + iov_from_buf(sg, elem->in_num, 0, &hdr, guest_offset); + total += guest_offset; } else { guest_offset = 0; } @@ -2009,11 +2016,11 @@ static ssize_t virtio_net_receive_rcu(NetClientState *nc, const uint8_t *buf, } if (mhdr_cnt) { - virtio_stw_p(vdev, &extra_hdr.hdr.num_buffers, i); + virtio_stw_p(vdev, &hdr.virtio_net.hdr.num_buffers, i); iov_from_buf(mhdr_sg, mhdr_cnt, 0, - &extra_hdr.hdr.num_buffers, - sizeof extra_hdr.hdr.num_buffers); + &hdr.virtio_net.hdr.num_buffers, + sizeof hdr.virtio_net.hdr.num_buffers); } for (j = 0; j < i; j++) {
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.odaki@daynix.com> --- hw/net/virtio-net.c | 85 +++++++++++++++++++++++++++++------------------------ 1 file changed, 46 insertions(+), 39 deletions(-)