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packet: Add GSO/csum offload support.
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This patch adds GSO/checksum offload to af_packet sockets using
virtio_net_hdr. Based on Rusty's patch to add this support to tun.
It allows GSO/checksum offload to be enabled when using raw socket
backend with virtio_net.
Adds PACKET_VNET_HDR socket option to prepend virtio_net_hdr in the
receive path and process/skip virtio_net_hdr in the send path. This
option is only allowed with SOCK_RAW sockets attached to ethernet
type devices.

v2 updates
----------
Michael's Comments
- Perform length check in packet_snd() when GSO is off even when
  vnet_hdr is present.
- Check for SKB_GSO_FCOE type and return -EINVAL
- don't allow tx/rx ring when vnet_hdr is enabled.
Herbert's Comments
- Removed ethernet specific code.
- protocol value is assumed to be passed in by the caller.

Signed-off-by: Sridhar Samudrala <sri@us.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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@davem330
Sridhar Samudrala authored and davem330 committed Feb 5, 2010
1 parent 746079d commit bfd5f4a
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Showing 2 changed files with 177 additions and 11 deletions.
1 change: 1 addition & 0 deletions include/linux/if_packet.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -46,6 +46,7 @@ struct sockaddr_ll {
#define PACKET_RESERVE 12
#define PACKET_TX_RING 13
#define PACKET_LOSS 14
#define PACKET_VNET_HDR 15

struct tpacket_stats {
unsigned int tp_packets;
Expand Down
187 changes: 176 additions & 11 deletions net/packet/af_packet.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -80,6 +80,7 @@
#include <linux/init.h>
#include <linux/mutex.h>
#include <linux/if_vlan.h>
#include <linux/virtio_net.h>

#ifdef CONFIG_INET
#include <net/inet_common.h>
Expand Down Expand Up @@ -193,7 +194,8 @@ struct packet_sock {
struct mutex pg_vec_lock;
unsigned int running:1, /* prot_hook is attached*/
auxdata:1,
origdev:1;
origdev:1,
has_vnet_hdr:1;
int ifindex; /* bound device */
__be16 num;
struct packet_mclist *mclist;
Expand Down Expand Up @@ -1056,6 +1058,30 @@ static int tpacket_snd(struct packet_sock *po, struct msghdr *msg)
}
#endif

static inline struct sk_buff *packet_alloc_skb(struct sock *sk, size_t prepad,
size_t reserve, size_t len,
size_t linear, int noblock,
int *err)
{
struct sk_buff *skb;

/* Under a page? Don't bother with paged skb. */
if (prepad + len < PAGE_SIZE || !linear)
linear = len;

skb = sock_alloc_send_pskb(sk, prepad + linear, len - linear, noblock,
err);
if (!skb)
return NULL;

skb_reserve(skb, reserve);
skb_put(skb, linear);
skb->data_len = len - linear;
skb->len += len - linear;

return skb;
}

static int packet_snd(struct socket *sock,
struct msghdr *msg, size_t len)
{
Expand All @@ -1066,14 +1092,17 @@ static int packet_snd(struct socket *sock,
__be16 proto;
unsigned char *addr;
int ifindex, err, reserve = 0;
struct virtio_net_hdr vnet_hdr = { 0 };
int offset = 0;
int vnet_hdr_len;
struct packet_sock *po = pkt_sk(sk);
unsigned short gso_type = 0;

/*
* Get and verify the address.
*/

if (saddr == NULL) {
struct packet_sock *po = pkt_sk(sk);

ifindex = po->ifindex;
proto = po->num;
addr = NULL;
Expand All @@ -1100,25 +1129,74 @@ static int packet_snd(struct socket *sock,
if (!(dev->flags & IFF_UP))
goto out_unlock;

if (po->has_vnet_hdr) {
vnet_hdr_len = sizeof(vnet_hdr);

err = -EINVAL;
if (len < vnet_hdr_len)
goto out_unlock;

len -= vnet_hdr_len;

err = memcpy_fromiovec((void *)&vnet_hdr, msg->msg_iov,
vnet_hdr_len);
if (err < 0)
goto out_unlock;

if ((vnet_hdr.flags & VIRTIO_NET_HDR_F_NEEDS_CSUM) &&
(vnet_hdr.csum_start + vnet_hdr.csum_offset + 2 >
vnet_hdr.hdr_len))
vnet_hdr.hdr_len = vnet_hdr.csum_start +
vnet_hdr.csum_offset + 2;

err = -EINVAL;
if (vnet_hdr.hdr_len > len)
goto out_unlock;

if (vnet_hdr.gso_type != VIRTIO_NET_HDR_GSO_NONE) {
switch (vnet_hdr.gso_type & ~VIRTIO_NET_HDR_GSO_ECN) {
case VIRTIO_NET_HDR_GSO_TCPV4:
gso_type = SKB_GSO_TCPV4;
break;
case VIRTIO_NET_HDR_GSO_TCPV6:
gso_type = SKB_GSO_TCPV6;
break;
case VIRTIO_NET_HDR_GSO_UDP:
gso_type = SKB_GSO_UDP;
break;
default:
goto out_unlock;
}

if (vnet_hdr.gso_type & VIRTIO_NET_HDR_GSO_ECN)
gso_type |= SKB_GSO_TCP_ECN;

if (vnet_hdr.gso_size == 0)
goto out_unlock;

}
}

err = -EMSGSIZE;
if (len > dev->mtu+reserve)
if (!gso_type && (len > dev->mtu+reserve))
goto out_unlock;

skb = sock_alloc_send_skb(sk, len + LL_ALLOCATED_SPACE(dev),
msg->msg_flags & MSG_DONTWAIT, &err);
err = -ENOBUFS;
skb = packet_alloc_skb(sk, LL_ALLOCATED_SPACE(dev),
LL_RESERVED_SPACE(dev), len, vnet_hdr.hdr_len,
msg->msg_flags & MSG_DONTWAIT, &err);
if (skb == NULL)
goto out_unlock;

skb_reserve(skb, LL_RESERVED_SPACE(dev));
skb_reset_network_header(skb);
skb_set_network_header(skb, reserve);

err = -EINVAL;
if (sock->type == SOCK_DGRAM &&
dev_hard_header(skb, dev, ntohs(proto), addr, NULL, len) < 0)
(offset = dev_hard_header(skb, dev, ntohs(proto), addr, NULL, len)) < 0)
goto out_free;

/* Returns -EFAULT on error */
err = memcpy_fromiovec(skb_put(skb, len), msg->msg_iov, len);
err = skb_copy_datagram_from_iovec(skb, offset, msg->msg_iov, 0, len);
if (err)
goto out_free;

Expand All @@ -1127,6 +1205,25 @@ static int packet_snd(struct socket *sock,
skb->priority = sk->sk_priority;
skb->mark = sk->sk_mark;

if (po->has_vnet_hdr) {
if (vnet_hdr.flags & VIRTIO_NET_HDR_F_NEEDS_CSUM) {
if (!skb_partial_csum_set(skb, vnet_hdr.csum_start,
vnet_hdr.csum_offset)) {
err = -EINVAL;
goto out_free;
}
}

skb_shinfo(skb)->gso_size = vnet_hdr.gso_size;
skb_shinfo(skb)->gso_type = gso_type;

/* Header must be checked, and gso_segs computed. */
skb_shinfo(skb)->gso_type |= SKB_GSO_DODGY;
skb_shinfo(skb)->gso_segs = 0;

len += vnet_hdr_len;
}

/*
* Now send it
*/
Expand Down Expand Up @@ -1420,6 +1517,7 @@ static int packet_recvmsg(struct kiocb *iocb, struct socket *sock,
struct sk_buff *skb;
int copied, err;
struct sockaddr_ll *sll;
int vnet_hdr_len = 0;

err = -EINVAL;
if (flags & ~(MSG_PEEK|MSG_DONTWAIT|MSG_TRUNC|MSG_CMSG_COMPAT))
Expand Down Expand Up @@ -1451,6 +1549,48 @@ static int packet_recvmsg(struct kiocb *iocb, struct socket *sock,
if (skb == NULL)
goto out;

if (pkt_sk(sk)->has_vnet_hdr) {
struct virtio_net_hdr vnet_hdr = { 0 };

err = -EINVAL;
vnet_hdr_len = sizeof(vnet_hdr);
if ((len -= vnet_hdr_len) < 0)
goto out_free;

if (skb_is_gso(skb)) {
struct skb_shared_info *sinfo = skb_shinfo(skb);

/* This is a hint as to how much should be linear. */
vnet_hdr.hdr_len = skb_headlen(skb);
vnet_hdr.gso_size = sinfo->gso_size;
if (sinfo->gso_type & SKB_GSO_TCPV4)
vnet_hdr.gso_type = VIRTIO_NET_HDR_GSO_TCPV4;
else if (sinfo->gso_type & SKB_GSO_TCPV6)
vnet_hdr.gso_type = VIRTIO_NET_HDR_GSO_TCPV6;
else if (sinfo->gso_type & SKB_GSO_UDP)
vnet_hdr.gso_type = VIRTIO_NET_HDR_GSO_UDP;
else if (sinfo->gso_type & SKB_GSO_FCOE)
goto out_free;
else
BUG();
if (sinfo->gso_type & SKB_GSO_TCP_ECN)
vnet_hdr.gso_type |= VIRTIO_NET_HDR_GSO_ECN;
} else
vnet_hdr.gso_type = VIRTIO_NET_HDR_GSO_NONE;

if (skb->ip_summed == CHECKSUM_PARTIAL) {
vnet_hdr.flags = VIRTIO_NET_HDR_F_NEEDS_CSUM;
vnet_hdr.csum_start = skb->csum_start -
skb_headroom(skb);
vnet_hdr.csum_offset = skb->csum_offset;
} /* else everything is zero */

err = memcpy_toiovec(msg->msg_iov, (void *)&vnet_hdr,
vnet_hdr_len);
if (err < 0)
goto out_free;
}

/*
* If the address length field is there to be filled in, we fill
* it in now.
Expand Down Expand Up @@ -1502,7 +1642,7 @@ static int packet_recvmsg(struct kiocb *iocb, struct socket *sock,
* Free or return the buffer as appropriate. Again this
* hides all the races and re-entrancy issues from us.
*/
err = (flags&MSG_TRUNC) ? skb->len : copied;
err = vnet_hdr_len + ((flags&MSG_TRUNC) ? skb->len : copied);

out_free:
skb_free_datagram(sk, skb);
Expand Down Expand Up @@ -1740,6 +1880,8 @@ packet_setsockopt(struct socket *sock, int level, int optname, char __user *optv

if (optlen < sizeof(req))
return -EINVAL;
if (pkt_sk(sk)->has_vnet_hdr)
return -EINVAL;
if (copy_from_user(&req, optval, sizeof(req)))
return -EFAULT;
return packet_set_ring(sk, &req, 0, optname == PACKET_TX_RING);
Expand Down Expand Up @@ -1826,6 +1968,22 @@ packet_setsockopt(struct socket *sock, int level, int optname, char __user *optv
po->origdev = !!val;
return 0;
}
case PACKET_VNET_HDR:
{
int val;

if (sock->type != SOCK_RAW)
return -EINVAL;
if (po->rx_ring.pg_vec || po->tx_ring.pg_vec)
return -EBUSY;
if (optlen < sizeof(val))
return -EINVAL;
if (copy_from_user(&val, optval, sizeof(val)))
return -EFAULT;

po->has_vnet_hdr = !!val;
return 0;
}
default:
return -ENOPROTOOPT;
}
Expand Down Expand Up @@ -1874,6 +2032,13 @@ static int packet_getsockopt(struct socket *sock, int level, int optname,
len = sizeof(int);
val = po->origdev;

data = &val;
break;
case PACKET_VNET_HDR:
if (len > sizeof(int))
len = sizeof(int);
val = po->has_vnet_hdr;

data = &val;
break;
#ifdef CONFIG_PACKET_MMAP
Expand Down

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