net/sched/sch_frag.c

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