linux/net/ipv4/udp_offload.c
Alexander Duyck 7fbeffed77 net: Update remote checksum segmentation to support use of GSO checksum
This patch addresses two main issues.

First in the case of remote checksum offload we were avoiding dealing with
scatter-gather issues.  As a result it would be possible to assemble a
series of frames that used frags instead of being linearized as they should
have if remote checksum offload was enabled.

Second I have updated the code so that we now let GSO take care of doing
the checksum on the data itself and drop the special case that was added
for remote checksum offload.

Signed-off-by: Alexander Duyck <aduyck@mirantis.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2016-02-11 08:55:33 -05:00

446 lines
11 KiB
C

/*
* IPV4 GSO/GRO offload support
* Linux INET implementation
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version
* 2 of the License, or (at your option) any later version.
*
* UDPv4 GSO support
*/
#include <linux/skbuff.h>
#include <net/udp.h>
#include <net/protocol.h>
static DEFINE_SPINLOCK(udp_offload_lock);
static struct udp_offload_priv __rcu *udp_offload_base __read_mostly;
#define udp_deref_protected(X) rcu_dereference_protected(X, lockdep_is_held(&udp_offload_lock))
struct udp_offload_priv {
struct udp_offload *offload;
possible_net_t net;
struct rcu_head rcu;
struct udp_offload_priv __rcu *next;
};
static struct sk_buff *__skb_udp_tunnel_segment(struct sk_buff *skb,
netdev_features_t features,
struct sk_buff *(*gso_inner_segment)(struct sk_buff *skb,
netdev_features_t features),
__be16 new_protocol, bool is_ipv6)
{
struct sk_buff *segs = ERR_PTR(-EINVAL);
u16 mac_offset = skb->mac_header;
int mac_len = skb->mac_len;
int tnl_hlen = skb_inner_mac_header(skb) - skb_transport_header(skb);
__be16 protocol = skb->protocol;
int udp_offset, outer_hlen;
unsigned int oldlen;
bool need_csum = !!(skb_shinfo(skb)->gso_type &
SKB_GSO_UDP_TUNNEL_CSUM);
bool remcsum = !!(skb_shinfo(skb)->gso_type & SKB_GSO_TUNNEL_REMCSUM);
bool offload_csum = false, dont_encap = (need_csum || remcsum);
oldlen = (u16)~skb->len;
if (unlikely(!pskb_may_pull(skb, tnl_hlen)))
goto out;
skb->encapsulation = 0;
__skb_pull(skb, tnl_hlen);
skb_reset_mac_header(skb);
skb_set_network_header(skb, skb_inner_network_offset(skb));
skb->mac_len = skb_inner_network_offset(skb);
skb->protocol = new_protocol;
skb->encap_hdr_csum = need_csum;
skb->remcsum_offload = remcsum;
/* Try to offload checksum if possible */
offload_csum = !!(need_csum &&
((skb->dev->features & NETIF_F_HW_CSUM) ||
(skb->dev->features & (is_ipv6 ?
NETIF_F_IPV6_CSUM : NETIF_F_IP_CSUM))));
features &= skb->dev->hw_enc_features;
/* The only checksum offload we care about from here on out is the
* outer one so strip the existing checksum feature flags and
* instead set the flag based on our outer checksum offload value.
*/
if (remcsum) {
features &= ~NETIF_F_CSUM_MASK;
if (offload_csum)
features |= NETIF_F_HW_CSUM;
}
/* segment inner packet. */
segs = gso_inner_segment(skb, features);
if (IS_ERR_OR_NULL(segs)) {
skb_gso_error_unwind(skb, protocol, tnl_hlen, mac_offset,
mac_len);
goto out;
}
outer_hlen = skb_tnl_header_len(skb);
udp_offset = outer_hlen - tnl_hlen;
skb = segs;
do {
struct udphdr *uh;
int len;
__be32 delta;
if (dont_encap) {
skb->encapsulation = 0;
skb->ip_summed = CHECKSUM_NONE;
} else {
/* Only set up inner headers if we might be offloading
* inner checksum.
*/
skb_reset_inner_headers(skb);
skb->encapsulation = 1;
}
skb->mac_len = mac_len;
skb->protocol = protocol;
skb_push(skb, outer_hlen);
skb_reset_mac_header(skb);
skb_set_network_header(skb, mac_len);
skb_set_transport_header(skb, udp_offset);
len = skb->len - udp_offset;
uh = udp_hdr(skb);
uh->len = htons(len);
if (!need_csum)
continue;
delta = htonl(oldlen + len);
uh->check = ~csum_fold((__force __wsum)
((__force u32)uh->check +
(__force u32)delta));
if (offload_csum) {
skb->ip_summed = CHECKSUM_PARTIAL;
skb->csum_start = skb_transport_header(skb) - skb->head;
skb->csum_offset = offsetof(struct udphdr, check);
} else {
uh->check = gso_make_checksum(skb, ~uh->check);
if (uh->check == 0)
uh->check = CSUM_MANGLED_0;
}
} while ((skb = skb->next));
out:
return segs;
}
struct sk_buff *skb_udp_tunnel_segment(struct sk_buff *skb,
netdev_features_t features,
bool is_ipv6)
{
__be16 protocol = skb->protocol;
const struct net_offload **offloads;
const struct net_offload *ops;
struct sk_buff *segs = ERR_PTR(-EINVAL);
struct sk_buff *(*gso_inner_segment)(struct sk_buff *skb,
netdev_features_t features);
rcu_read_lock();
switch (skb->inner_protocol_type) {
case ENCAP_TYPE_ETHER:
protocol = skb->inner_protocol;
gso_inner_segment = skb_mac_gso_segment;
break;
case ENCAP_TYPE_IPPROTO:
offloads = is_ipv6 ? inet6_offloads : inet_offloads;
ops = rcu_dereference(offloads[skb->inner_ipproto]);
if (!ops || !ops->callbacks.gso_segment)
goto out_unlock;
gso_inner_segment = ops->callbacks.gso_segment;
break;
default:
goto out_unlock;
}
segs = __skb_udp_tunnel_segment(skb, features, gso_inner_segment,
protocol, is_ipv6);
out_unlock:
rcu_read_unlock();
return segs;
}
static struct sk_buff *udp4_ufo_fragment(struct sk_buff *skb,
netdev_features_t features)
{
struct sk_buff *segs = ERR_PTR(-EINVAL);
unsigned int mss;
__wsum csum;
struct udphdr *uh;
struct iphdr *iph;
if (skb->encapsulation &&
(skb_shinfo(skb)->gso_type &
(SKB_GSO_UDP_TUNNEL|SKB_GSO_UDP_TUNNEL_CSUM))) {
segs = skb_udp_tunnel_segment(skb, features, false);
goto out;
}
if (!pskb_may_pull(skb, sizeof(struct udphdr)))
goto out;
mss = skb_shinfo(skb)->gso_size;
if (unlikely(skb->len <= mss))
goto out;
if (skb_gso_ok(skb, features | NETIF_F_GSO_ROBUST)) {
/* Packet is from an untrusted source, reset gso_segs. */
int type = skb_shinfo(skb)->gso_type;
if (unlikely(type & ~(SKB_GSO_UDP | SKB_GSO_DODGY |
SKB_GSO_UDP_TUNNEL |
SKB_GSO_UDP_TUNNEL_CSUM |
SKB_GSO_TUNNEL_REMCSUM |
SKB_GSO_IPIP |
SKB_GSO_GRE | SKB_GSO_GRE_CSUM) ||
!(type & (SKB_GSO_UDP))))
goto out;
skb_shinfo(skb)->gso_segs = DIV_ROUND_UP(skb->len, mss);
segs = NULL;
goto out;
}
/* Do software UFO. Complete and fill in the UDP checksum as
* HW cannot do checksum of UDP packets sent as multiple
* IP fragments.
*/
uh = udp_hdr(skb);
iph = ip_hdr(skb);
uh->check = 0;
csum = skb_checksum(skb, 0, skb->len, 0);
uh->check = udp_v4_check(skb->len, iph->saddr, iph->daddr, csum);
if (uh->check == 0)
uh->check = CSUM_MANGLED_0;
skb->ip_summed = CHECKSUM_NONE;
/* Fragment the skb. IP headers of the fragments are updated in
* inet_gso_segment()
*/
segs = skb_segment(skb, features);
out:
return segs;
}
int udp_add_offload(struct net *net, struct udp_offload *uo)
{
struct udp_offload_priv *new_offload = kzalloc(sizeof(*new_offload), GFP_ATOMIC);
if (!new_offload)
return -ENOMEM;
write_pnet(&new_offload->net, net);
new_offload->offload = uo;
spin_lock(&udp_offload_lock);
new_offload->next = udp_offload_base;
rcu_assign_pointer(udp_offload_base, new_offload);
spin_unlock(&udp_offload_lock);
return 0;
}
EXPORT_SYMBOL(udp_add_offload);
static void udp_offload_free_routine(struct rcu_head *head)
{
struct udp_offload_priv *ou_priv = container_of(head, struct udp_offload_priv, rcu);
kfree(ou_priv);
}
void udp_del_offload(struct udp_offload *uo)
{
struct udp_offload_priv __rcu **head = &udp_offload_base;
struct udp_offload_priv *uo_priv;
spin_lock(&udp_offload_lock);
uo_priv = udp_deref_protected(*head);
for (; uo_priv != NULL;
uo_priv = udp_deref_protected(*head)) {
if (uo_priv->offload == uo) {
rcu_assign_pointer(*head,
udp_deref_protected(uo_priv->next));
goto unlock;
}
head = &uo_priv->next;
}
pr_warn("udp_del_offload: didn't find offload for port %d\n", ntohs(uo->port));
unlock:
spin_unlock(&udp_offload_lock);
if (uo_priv)
call_rcu(&uo_priv->rcu, udp_offload_free_routine);
}
EXPORT_SYMBOL(udp_del_offload);
struct sk_buff **udp_gro_receive(struct sk_buff **head, struct sk_buff *skb,
struct udphdr *uh)
{
struct udp_offload_priv *uo_priv;
struct sk_buff *p, **pp = NULL;
struct udphdr *uh2;
unsigned int off = skb_gro_offset(skb);
int flush = 1;
if (NAPI_GRO_CB(skb)->udp_mark ||
(skb->ip_summed != CHECKSUM_PARTIAL &&
NAPI_GRO_CB(skb)->csum_cnt == 0 &&
!NAPI_GRO_CB(skb)->csum_valid))
goto out;
/* mark that this skb passed once through the udp gro layer */
NAPI_GRO_CB(skb)->udp_mark = 1;
rcu_read_lock();
uo_priv = rcu_dereference(udp_offload_base);
for (; uo_priv != NULL; uo_priv = rcu_dereference(uo_priv->next)) {
if (net_eq(read_pnet(&uo_priv->net), dev_net(skb->dev)) &&
uo_priv->offload->port == uh->dest &&
uo_priv->offload->callbacks.gro_receive)
goto unflush;
}
goto out_unlock;
unflush:
flush = 0;
for (p = *head; p; p = p->next) {
if (!NAPI_GRO_CB(p)->same_flow)
continue;
uh2 = (struct udphdr *)(p->data + off);
/* Match ports and either checksums are either both zero
* or nonzero.
*/
if ((*(u32 *)&uh->source != *(u32 *)&uh2->source) ||
(!uh->check ^ !uh2->check)) {
NAPI_GRO_CB(p)->same_flow = 0;
continue;
}
}
skb_gro_pull(skb, sizeof(struct udphdr)); /* pull encapsulating udp header */
skb_gro_postpull_rcsum(skb, uh, sizeof(struct udphdr));
NAPI_GRO_CB(skb)->proto = uo_priv->offload->ipproto;
pp = uo_priv->offload->callbacks.gro_receive(head, skb,
uo_priv->offload);
out_unlock:
rcu_read_unlock();
out:
NAPI_GRO_CB(skb)->flush |= flush;
return pp;
}
static struct sk_buff **udp4_gro_receive(struct sk_buff **head,
struct sk_buff *skb)
{
struct udphdr *uh = udp_gro_udphdr(skb);
if (unlikely(!uh))
goto flush;
/* Don't bother verifying checksum if we're going to flush anyway. */
if (NAPI_GRO_CB(skb)->flush)
goto skip;
if (skb_gro_checksum_validate_zero_check(skb, IPPROTO_UDP, uh->check,
inet_gro_compute_pseudo))
goto flush;
else if (uh->check)
skb_gro_checksum_try_convert(skb, IPPROTO_UDP, uh->check,
inet_gro_compute_pseudo);
skip:
NAPI_GRO_CB(skb)->is_ipv6 = 0;
return udp_gro_receive(head, skb, uh);
flush:
NAPI_GRO_CB(skb)->flush = 1;
return NULL;
}
int udp_gro_complete(struct sk_buff *skb, int nhoff)
{
struct udp_offload_priv *uo_priv;
__be16 newlen = htons(skb->len - nhoff);
struct udphdr *uh = (struct udphdr *)(skb->data + nhoff);
int err = -ENOSYS;
uh->len = newlen;
rcu_read_lock();
uo_priv = rcu_dereference(udp_offload_base);
for (; uo_priv != NULL; uo_priv = rcu_dereference(uo_priv->next)) {
if (net_eq(read_pnet(&uo_priv->net), dev_net(skb->dev)) &&
uo_priv->offload->port == uh->dest &&
uo_priv->offload->callbacks.gro_complete)
break;
}
if (uo_priv) {
NAPI_GRO_CB(skb)->proto = uo_priv->offload->ipproto;
err = uo_priv->offload->callbacks.gro_complete(skb,
nhoff + sizeof(struct udphdr),
uo_priv->offload);
}
rcu_read_unlock();
if (skb->remcsum_offload)
skb_shinfo(skb)->gso_type |= SKB_GSO_TUNNEL_REMCSUM;
skb->encapsulation = 1;
skb_set_inner_mac_header(skb, nhoff + sizeof(struct udphdr));
return err;
}
static int udp4_gro_complete(struct sk_buff *skb, int nhoff)
{
const struct iphdr *iph = ip_hdr(skb);
struct udphdr *uh = (struct udphdr *)(skb->data + nhoff);
if (uh->check) {
skb_shinfo(skb)->gso_type |= SKB_GSO_UDP_TUNNEL_CSUM;
uh->check = ~udp_v4_check(skb->len - nhoff, iph->saddr,
iph->daddr, 0);
} else {
skb_shinfo(skb)->gso_type |= SKB_GSO_UDP_TUNNEL;
}
return udp_gro_complete(skb, nhoff);
}
static const struct net_offload udpv4_offload = {
.callbacks = {
.gso_segment = udp4_ufo_fragment,
.gro_receive = udp4_gro_receive,
.gro_complete = udp4_gro_complete,
},
};
int __init udpv4_offload_init(void)
{
return inet_add_offload(&udpv4_offload, IPPROTO_UDP);
}