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, 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, 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); 153