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// SPDX-License-Identifier: GPL-2.0 OR Linux-OpenIB
#include <net/netlink.h>
#include <net/sch_generic.h>
#include <net/pkt_sched.h>
#include <net/dst.h>
#include <net/ip.h>
#include <net/ip6_fib.h>
struct sch_frag_data {
unsigned long dst;
struct qdisc_skb_cb cb;
__be16 inner_protocol;
u16 vlan_tci;
__be16 vlan_proto;
unsigned int l2_len;
u8 l2_data[VLAN_ETH_HLEN];
int (*xmit)(struct sk_buff *skb);
};
static DEFINE_PER_CPU(struct sch_frag_data, sch_frag_data_storage);
static int sch_frag_xmit(struct net *net, struct sock *sk, struct sk_buff *skb)
{
struct sch_frag_data *data = this_cpu_ptr(&sch_frag_data_storage);
if (skb_cow_head(skb, data->l2_len) < 0) {
kfree_skb(skb);
return -ENOMEM;
}
__skb_dst_copy(skb, data->dst);
*qdisc_skb_cb(skb) = data->cb;
skb->inner_protocol = data->inner_protocol;
if (data->vlan_tci & VLAN_CFI_MASK)
__vlan_hwaccel_put_tag(skb, data->vlan_proto,
data->vlan_tci & ~VLAN_CFI_MASK);
else
__vlan_hwaccel_clear_tag(skb);
/* Reconstruct the MAC header. */
skb_push(skb, data->l2_len);
memcpy(skb->data, &data->l2_data, data->l2_len);
skb_postpush_rcsum(skb, skb->data, data->l2_len);
skb_reset_mac_header(skb);
return data->xmit(skb);
}
static void sch_frag_prepare_frag(struct sk_buff *skb,
int (*xmit)(struct sk_buff *skb))
{
unsigned int hlen = skb_network_offset(skb);
struct sch_frag_data *data;
data = this_cpu_ptr(&sch_frag_data_storage);
data->dst = skb->_skb_refdst;
data->cb = *qdisc_skb_cb(skb);
data->xmit = xmit;
data->inner_protocol = skb->inner_protocol;
if (skb_vlan_tag_present(skb))
data->vlan_tci = skb_vlan_tag_get(skb) | VLAN_CFI_MASK;
else
data->vlan_tci = 0;
data->vlan_proto = skb->vlan_proto;
data->l2_len = hlen;
memcpy(&data->l2_data, skb->data, hlen);
memset(IPCB(skb), 0, sizeof(struct inet_skb_parm));
skb_pull(skb, hlen);
}
static unsigned int
sch_frag_dst_get_mtu(const struct dst_entry *dst)
{
return dst->dev->mtu;
}
static struct dst_ops sch_frag_dst_ops = {
.family = AF_UNSPEC,
.mtu = sch_frag_dst_get_mtu,
};
static int sch_fragment(struct net *net, struct sk_buff *skb,
u16 mru, int (*xmit)(struct sk_buff *skb))
{
int ret = -1;
if (skb_network_offset(skb) > VLAN_ETH_HLEN) {
net_warn_ratelimited("L2 header too long to fragment\n");
goto err;
}
if (skb_protocol(skb, true) == htons(ETH_P_IP)) {
struct rtable sch_frag_rt = { 0 };
unsigned long orig_dst;
sch_frag_prepare_frag(skb, xmit);
dst_init(&sch_frag_rt.dst, &sch_frag_dst_ops, NULL, 1,
DST_OBSOLETE_NONE, DST_NOCOUNT);
sch_frag_rt.dst.dev = skb->dev;
orig_dst = skb->_skb_refdst;
skb_dst_set_noref(skb, &sch_frag_rt.dst);
IPCB(skb)->frag_max_size = mru;
ret = ip_do_fragment(net, skb->sk, skb, sch_frag_xmit);
refdst_drop(orig_dst);
} else if (skb_protocol(skb, true) == htons(ETH_P_IPV6)) {
unsigned long orig_dst;
struct rt6_info sch_frag_rt;
sch_frag_prepare_frag(skb, xmit);
memset(&sch_frag_rt, 0, sizeof(sch_frag_rt));
dst_init(&sch_frag_rt.dst, &sch_frag_dst_ops, NULL, 1,
DST_OBSOLETE_NONE, DST_NOCOUNT);
sch_frag_rt.dst.dev = skb->dev;
orig_dst = skb->_skb_refdst;
skb_dst_set_noref(skb, &sch_frag_rt.dst);
IP6CB(skb)->frag_max_size = mru;
ret = ipv6_stub->ipv6_fragment(net, skb->sk, skb,
sch_frag_xmit);
refdst_drop(orig_dst);
} else {
net_warn_ratelimited("Fail frag %s: eth=%x, MRU=%d, MTU=%d\n",
netdev_name(skb->dev),
ntohs(skb_protocol(skb, true)), mru,
skb->dev->mtu);
goto err;
}
return ret;
err:
kfree_skb(skb);
return ret;
}
int sch_frag_xmit_hook(struct sk_buff *skb, int (*xmit)(struct sk_buff *skb))
{
u16 mru = tc_skb_cb(skb)->mru;
int err;
if (mru && skb->len > mru + skb->dev->hard_header_len)
err = sch_fragment(dev_net(skb->dev), skb, mru, xmit);
else
err = xmit(skb);
return err;
}
EXPORT_SYMBOL_GPL(sch_frag_xmit_hook);
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