LXR linux/net/sched/sch

   1// SPDX-License-Identifier: GPL-2.0 OR Linux-OpenIB
   2#include <linux/if_vlan.h>
   3#include <net/netlink.h>
   4#include <net/sch_generic.h>
   5#include <net/pkt_sched.h>
   6#include <net/dst.h>
   7#include <net/ip.h>
   8#include <net/ip6_fib.h>
   9
  10struct sch_frag_data {
  11        unsigned long dst;
  12        struct qdisc_skb_cb cb;
  13        __be16 inner_protocol;
  14        u16 vlan_tci;
  15        __be16 vlan_proto;
  16        unsigned int l2_len;
  17        u8 l2_data[VLAN_ETH_HLEN];
  18        int (*xmit)(struct sk_buff *skb);
  19};
  20
  21static DEFINE_PER_CPU(struct sch_frag_data, sch_frag_data_storage);
  22
  23static int sch_frag_xmit(struct net *net, struct sock *sk, struct sk_buff *skb)
  24{
  25        struct sch_frag_data *data = this_cpu_ptr(&sch_frag_data_storage);
  26
  27        if (skb_cow_head(skb, data->l2_len) < 0) {
  28                kfree_skb(skb);
  29                return -ENOMEM;
  30        }
  31
  32        __skb_dst_copy(skb, data->dst);
  33        *qdisc_skb_cb(skb) = data->cb;
  34        skb->inner_protocol = data->inner_protocol;
  35        if (data->vlan_tci & VLAN_CFI_MASK)
  36                __vlan_hwaccel_put_tag(skb, data->vlan_proto,
  37                                       data->vlan_tci & ~VLAN_CFI_MASK);
  38        else
  39                __vlan_hwaccel_clear_tag(skb);
  40
  41        /* Reconstruct the MAC header.  */
  42        skb_push(skb, data->l2_len);
  43        memcpy(skb->data, &data->l2_data, data->l2_len);
  44        skb_postpush_rcsum(skb, skb->data, data->l2_len);
  45        skb_reset_mac_header(skb);
  46
  47        return data->xmit(skb);
  48}
  49
  50static void sch_frag_prepare_frag(struct sk_buff *skb,
  51                                  int (*xmit)(struct sk_buff *skb))
  52{
  53        unsigned int hlen = skb_network_offset(skb);
  54        struct sch_frag_data *data;
  55
  56        data = this_cpu_ptr(&sch_frag_data_storage);
  57        data->dst = skb->_skb_refdst;
  58        data->cb = *qdisc_skb_cb(skb);
  59        data->xmit = xmit;
  60        data->inner_protocol = skb->inner_protocol;
  61        if (skb_vlan_tag_present(skb))
  62                data->vlan_tci = skb_vlan_tag_get(skb) | VLAN_CFI_MASK;
  63        else
  64                data->vlan_tci = 0;
  65        data->vlan_proto = skb->vlan_proto;
  66        data->l2_len = hlen;
  67        memcpy(&data->l2_data, skb->data, hlen);
  68
  69        memset(IPCB(skb), 0, sizeof(struct inet_skb_parm));
  70        skb_pull(skb, hlen);
  71}
  72
  73static unsigned int
  74sch_frag_dst_get_mtu(const struct dst_entry *dst)
  75{
  76        return dst->dev->mtu;
  77}
  78
  79static struct dst_ops sch_frag_dst_ops = {
  80        .family = AF_UNSPEC,
  81        .mtu = sch_frag_dst_get_mtu,
  82};
  83
  84static int sch_fragment(struct net *net, struct sk_buff *skb,
  85                        u16 mru, int (*xmit)(struct sk_buff *skb))
  86{
  87        int ret = -1;
  88
  89        if (skb_network_offset(skb) > VLAN_ETH_HLEN) {
  90                net_warn_ratelimited("L2 header too long to fragment\n");
  91                goto err;
  92        }
  93
  94        if (skb_protocol(skb, true) == htons(ETH_P_IP)) {
  95                struct rtable sch_frag_rt = { 0 };
  96                unsigned long orig_dst;
  97
  98                sch_frag_prepare_frag(skb, xmit);
  99                dst_init(&sch_frag_rt.dst, &sch_frag_dst_ops, NULL, 1,
 100                         DST_OBSOLETE_NONE, DST_NOCOUNT);
 101                sch_frag_rt.dst.dev = skb->dev;
 102
 103                orig_dst = skb->_skb_refdst;
 104                skb_dst_set_noref(skb, &sch_frag_rt.dst);
 105                IPCB(skb)->frag_max_size = mru;
 106
 107                ret = ip_do_fragment(net, skb->sk, skb, sch_frag_xmit);
 108                refdst_drop(orig_dst);
 109        } else if (skb_protocol(skb, true) == htons(ETH_P_IPV6)) {
 110                unsigned long orig_dst;
 111                struct rt6_info sch_frag_rt;
 112
 113                sch_frag_prepare_frag(skb, xmit);
 114                memset(&sch_frag_rt, 0, sizeof(sch_frag_rt));
 115                dst_init(&sch_frag_rt.dst, &sch_frag_dst_ops, NULL, 1,
 116                         DST_OBSOLETE_NONE, DST_NOCOUNT);
 117                sch_frag_rt.dst.dev = skb->dev;
 118
 119                orig_dst = skb->_skb_refdst;
 120                skb_dst_set_noref(skb, &sch_frag_rt.dst);
 121                IP6CB(skb)->frag_max_size = mru;
 122
 123                ret = ipv6_stub->ipv6_fragment(net, skb->sk, skb,
 124                                               sch_frag_xmit);
 125                refdst_drop(orig_dst);
 126        } else {
 127                net_warn_ratelimited("Fail frag %s: eth=%x, MRU=%d, MTU=%d\n",
 128                                     netdev_name(skb->dev),
 129                                     ntohs(skb_protocol(skb, true)), mru,
 130                                     skb->dev->mtu);
 131                goto err;
 132        }
 133
 134        return ret;
 135err:
 136        kfree_skb(skb);
 137        return ret;
 138}
 139
 140int sch_frag_xmit_hook(struct sk_buff *skb, int (*xmit)(struct sk_buff *skb))
 141{
 142        u16 mru = tc_skb_cb(skb)->mru;
 143        int err;
 144
 145        if (mru && skb->len > mru + skb->dev->hard_header_len)
 146                err = sch_fragment(dev_net(skb->dev), skb, mru, xmit);
 147        else
 148                err = xmit(skb);
 149
 150        return err;
 151}
 152EXPORT_SYMBOL_GPL(sch_frag_xmit_hook);
 153