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