linux/net/ipv4/udp_offload.c

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/*
* 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;
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;
netdev_features_t enc_features;
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 &
(is_ipv6 ? NETIF_F_V6_CSUM : NETIF_F_V4_CSUM)));
/* segment inner packet. */
enc_features = skb->dev->hw_enc_features & features;
segs = gso_inner_segment(skb, enc_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 if (remcsum) {
/* Need to calculate checksum from scratch,
* inner checksums are never when doing
* remote_checksum_offload.
*/
skb->csum = skb_checksum(skb, udp_offset,
skb->len - udp_offset,
0);
uh->check = csum_fold(skb->csum);
if (uh->check == 0)
uh->check = CSUM_MANGLED_0;
} 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 udp_offload *uo)
{
struct udp_offload_priv *new_offload = kzalloc(sizeof(*new_offload), GFP_ATOMIC);
if (!new_offload)
return -ENOMEM;
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 != NULL)
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 (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);
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 (uo_priv->offload->port == uh->dest &&
uo_priv->offload->callbacks.gro_complete)
break;
}
if (uo_priv != NULL) {
NAPI_GRO_CB(skb)->proto = uo_priv->offload->ipproto;
err = uo_priv->offload->callbacks.gro_complete(skb, nhoff + sizeof(struct udphdr));
}
rcu_read_unlock();
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)
uh->check = ~udp_v4_check(skb->len - nhoff, iph->saddr,
iph->daddr, 0);
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);
}