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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 int gre_gso_send_check(struct sk_buff *skb)
{
if (!skb->encapsulation)
return -EINVAL;
return 0;
}
static struct sk_buff *gre_gso_segment(struct sk_buff *skb,
netdev_features_t features)
{
struct sk_buff *segs = ERR_PTR(-EINVAL);
netdev_features_t enc_features;
int ghl;
struct gre_base_hdr *greh;
u16 mac_offset = skb->mac_header;
int mac_len = skb->mac_len;
__be16 protocol = skb->protocol;
int tnl_hlen;
bool csum;
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_IPIP)))
goto out;
if (unlikely(!pskb_may_pull(skb, sizeof(*greh))))
goto out;
greh = (struct gre_base_hdr *)skb_transport_header(skb);
ghl = skb_inner_network_header(skb) - skb_transport_header(skb);
if (unlikely(ghl < sizeof(*greh)))
goto out;
csum = !!(greh->flags & GRE_CSUM);
if (unlikely(!pskb_may_pull(skb, ghl)))
goto out;
/* setup inner skb. */
skb->protocol = greh->protocol;
skb->encapsulation = 0;
__skb_pull(skb, ghl);
skb_reset_mac_header(skb);
skb_set_network_header(skb, skb_inner_network_offset(skb));
skb->mac_len = skb_inner_network_offset(skb);
/* segment inner packet. */
enc_features = skb->dev->hw_enc_features & netif_skb_features(skb);
segs = skb_mac_gso_segment(skb, enc_features);
if (!segs || IS_ERR(segs)) {
skb_gso_error_unwind(skb, protocol, ghl, mac_offset, mac_len);
goto out;
}
skb = segs;
tnl_hlen = skb_tnl_header_len(skb);
do {
__skb_push(skb, ghl);
if (csum) {
__be32 *pcsum;
if (skb_has_shared_frag(skb)) {
int err;
err = __skb_linearize(skb);
if (err) {
kfree_skb_list(segs);
segs = ERR_PTR(err);
goto out;
}
}
greh = (struct gre_base_hdr *)(skb->data);
pcsum = (__be32 *)(greh + 1);
*pcsum = 0;
*(__sum16 *)pcsum = csum_fold(skb_checksum(skb, 0, skb->len, 0));
}
__skb_push(skb, tnl_hlen - ghl);
skb_reset_inner_headers(skb);
skb->encapsulation = 1;
skb_reset_mac_header(skb);
skb_set_network_header(skb, mac_len);
skb->mac_len = mac_len;
skb->protocol = protocol;
} while ((skb = skb->next));
out:
return segs;
}
/* Compute the whole skb csum in s/w and store it, then verify GRO csum
* starting from gro_offset.
*/
static __sum16 gro_skb_checksum(struct sk_buff *skb)
{
__sum16 sum;
skb->csum = skb_checksum(skb, 0, skb->len, 0);
NAPI_GRO_CB(skb)->csum = csum_sub(skb->csum,
csum_partial(skb->data, skb_gro_offset(skb), 0));
sum = csum_fold(NAPI_GRO_CB(skb)->csum);
if (unlikely(skb->ip_summed == CHECKSUM_COMPLETE)) {
if (unlikely(!sum))
netdev_rx_csum_fault(skb->dev);
} else
skb->ip_summed = CHECKSUM_COMPLETE;
return sum;
}
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;
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;
type = greh->protocol;
rcu_read_lock();
ptype = gro_find_receive_by_type(type);
if (ptype == NULL)
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;
}
if (greh->flags & GRE_CSUM) { /* Need to verify GRE csum first */
__sum16 csum = 0;
if (skb->ip_summed == CHECKSUM_COMPLETE)
csum = csum_fold(NAPI_GRO_CB(skb)->csum);
/* Don't trust csum error calculated/reported by h/w */
if (skb->ip_summed == CHECKSUM_NONE || csum != 0)
csum = gro_skb_checksum(skb);
/* GRE CSUM is the 1's complement of the 1's complement sum
* of the GRE hdr plus payload so it should add up to 0xffff
* (and 0 after csum_fold()) just like the IPv4 hdr csum.
*/
if (csum)
goto out_unlock;
}
flush = 0;
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);
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 != NULL)
err = ptype->callbacks.gro_complete(skb, nhoff + grehlen);
rcu_read_unlock();
return err;
}
static const struct net_offload gre_offload = {
.callbacks = {
.gso_send_check = gre_gso_send_check,
.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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