net/sched/sch_frag.c

   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
  10 struct 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
  21 static DEFINE_PER_CPU(struct sch_frag_data, sch_frag_data_storage);
  22
  23 static 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
  50 static 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
  73 static unsigned int
  74 sch_frag_dst_get_mtu(const struct dst_entry *dst)
  75 {
  76         return dst->dev->mtu;
  77 }
  78
  79 static struct dst_ops sch_frag_dst_ops = {
  80         .family = AF_UNSPEC,
  81         .mtu = sch_frag_dst_get_mtu,
  82 };
  83
  84 static 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;
 135 err:
 136         kfree_skb(skb);
 137         return ret;
 138 }
 139
 140 int 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 }
 152 EXPORT_SYMBOL_GPL(sch_frag_xmit_hook);