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;
+
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++) {
--
2.46.0On 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
© 2016 - 2024 Red Hat, Inc.