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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.
*
* GRE GSO support
*/
#include <linux/skbuff.h>
#include <linux/init.h>
#include <net/protocol.h>
#include <net/gre.h>
static struct sk_buff *gre_gso_segment(struct sk_buff *skb,
netdev_features_t features)
{
int tnl_hlen = skb_inner_mac_header(skb) - skb_transport_header(skb);
struct sk_buff *segs = ERR_PTR(-EINVAL);
u16 mac_offset = skb->mac_header;
__be16 protocol = skb->protocol;
u16 mac_len = skb->mac_len;
int gre_offset, outer_hlen;
bool need_csum, ufo;
if (unlikely(skb_shinfo(skb)->gso_type &
~(SKB_GSO_TCPV4 |
SKB_GSO_TCPV6 |
SKB_GSO_UDP |
SKB_GSO_DODGY |
SKB_GSO_TCP_ECN |
SKB_GSO_GRE |
SKB_GSO_GRE_CSUM |
SKB_GSO_IPIP |
SKB_GSO_SIT)))
goto out;
if (!skb->encapsulation)
goto out;
if (unlikely(tnl_hlen < sizeof(struct gre_base_hdr)))
goto out;
if (unlikely(!pskb_may_pull(skb, tnl_hlen)))
goto out;
/* setup inner skb. */
skb->encapsulation = 0;
SKB_GSO_CB(skb)->encap_level = 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 = skb->inner_protocol;
need_csum = !!(skb_shinfo(skb)->gso_type & SKB_GSO_GRE_CSUM);
skb->encap_hdr_csum = need_csum;
ufo = !!(skb_shinfo(skb)->gso_type & SKB_GSO_UDP);
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 based
* on the fact that we will be computing our checksum in software.
*/
if (ufo) {
features &= ~NETIF_F_CSUM_MASK;
if (!need_csum)
features |= NETIF_F_HW_CSUM;
}
/* segment inner packet. */
segs = skb_mac_gso_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);
gre_offset = outer_hlen - tnl_hlen;
skb = segs;
do {
struct gre_base_hdr *greh;
__be32 *pcsum;
/* Set up inner headers if we are offloading inner checksum */
if (skb->ip_summed == CHECKSUM_PARTIAL) {
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, gre_offset);
if (!need_csum)
continue;
greh = (struct gre_base_hdr *)skb_transport_header(skb);
pcsum = (__be32 *)(greh + 1);
*pcsum = 0;
*(__sum16 *)pcsum = gso_make_checksum(skb, 0);
} while ((skb = skb->next));
out:
return segs;
}
static struct sk_buff **gre_gro_receive(struct sk_buff **head,
struct sk_buff *skb)
{
struct sk_buff **pp = NULL;
struct sk_buff *p;
const struct gre_base_hdr *greh;
unsigned int hlen, grehlen;
unsigned int off;
int flush = 1;
struct packet_offload *ptype;
__be16 type;
if (NAPI_GRO_CB(skb)->encap_mark)
goto out;
NAPI_GRO_CB(skb)->encap_mark = 1;
off = skb_gro_offset(skb);
hlen = off + sizeof(*greh);
greh = skb_gro_header_fast(skb, off);
if (skb_gro_header_hard(skb, hlen)) {
greh = skb_gro_header_slow(skb, hlen, off);
if (unlikely(!greh))
goto out;
}
/* Only support version 0 and K (key), C (csum) flags. Note that
* although the support for the S (seq#) flag can be added easily
* for GRO, this is problematic for GSO hence can not be enabled
* here because a GRO pkt may end up in the forwarding path, thus
* requiring GSO support to break it up correctly.
*/
if ((greh->flags & ~(GRE_KEY|GRE_CSUM)) != 0)
goto out;
/* We can only support GRE_CSUM if we can track the location of
* the GRE header. In the case of FOU/GUE we cannot because the
* outer UDP header displaces the GRE header leaving us in a state
* of limbo.
*/
if ((greh->flags & GRE_CSUM) && NAPI_GRO_CB(skb)->is_fou)
goto out;
type = greh->protocol;
rcu_read_lock();
ptype = gro_find_receive_by_type(type);
if (!ptype)
goto out_unlock;
grehlen = GRE_HEADER_SECTION;
if (greh->flags & GRE_KEY)
grehlen += GRE_HEADER_SECTION;
if (greh->flags & GRE_CSUM)
grehlen += GRE_HEADER_SECTION;
hlen = off + grehlen;
if (skb_gro_header_hard(skb, hlen)) {
greh = skb_gro_header_slow(skb, hlen, off);
if (unlikely(!greh))
goto out_unlock;
}
/* Don't bother verifying checksum if we're going to flush anyway. */
if ((greh->flags & GRE_CSUM) && !NAPI_GRO_CB(skb)->flush) {
if (skb_gro_checksum_simple_validate(skb))
goto out_unlock;
skb_gro_checksum_try_convert(skb, IPPROTO_GRE, 0,
null_compute_pseudo);
}
for (p = *head; p; p = p->next) {
const struct gre_base_hdr *greh2;
if (!NAPI_GRO_CB(p)->same_flow)
continue;
/* The following checks are needed to ensure only pkts
* from the same tunnel are considered for aggregation.
* The criteria for "the same tunnel" includes:
* 1) same version (we only support version 0 here)
* 2) same protocol (we only support ETH_P_IP for now)
* 3) same set of flags
* 4) same key if the key field is present.
*/
greh2 = (struct gre_base_hdr *)(p->data + off);
if (greh2->flags != greh->flags ||
greh2->protocol != greh->protocol) {
NAPI_GRO_CB(p)->same_flow = 0;
continue;
}
if (greh->flags & GRE_KEY) {
/* compare keys */
if (*(__be32 *)(greh2+1) != *(__be32 *)(greh+1)) {
NAPI_GRO_CB(p)->same_flow = 0;
continue;
}
}
}
skb_gro_pull(skb, grehlen);
/* Adjusted NAPI_GRO_CB(skb)->csum after skb_gro_pull()*/
skb_gro_postpull_rcsum(skb, greh, grehlen);
pp = ptype->callbacks.gro_receive(head, skb);
flush = 0;
out_unlock:
rcu_read_unlock();
out:
NAPI_GRO_CB(skb)->flush |= flush;
return pp;
}
static int gre_gro_complete(struct sk_buff *skb, int nhoff)
{
struct gre_base_hdr *greh = (struct gre_base_hdr *)(skb->data + nhoff);
struct packet_offload *ptype;
unsigned int grehlen = sizeof(*greh);
int err = -ENOENT;
__be16 type;
skb->encapsulation = 1;
skb_shinfo(skb)->gso_type = SKB_GSO_GRE;
type = greh->protocol;
if (greh->flags & GRE_KEY)
grehlen += GRE_HEADER_SECTION;
if (greh->flags & GRE_CSUM)
grehlen += GRE_HEADER_SECTION;
rcu_read_lock();
ptype = gro_find_complete_by_type(type);
if (ptype)
err = ptype->callbacks.gro_complete(skb, nhoff + grehlen);
rcu_read_unlock();
skb_set_inner_mac_header(skb, nhoff + grehlen);
return err;
}
static const struct net_offload gre_offload = {
.callbacks = {
.gso_segment = gre_gso_segment,
.gro_receive = gre_gro_receive,
.gro_complete = gre_gro_complete,
},
};
static int __init gre_offload_init(void)
{
return inet_add_offload(&gre_offload, IPPROTO_GRE);
}
device_initcall(gre_offload_init);
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