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 local_lock_t bh_lock; 20 }; 21 22 static DEFINE_PER_CPU(struct sch_frag_data, sch_frag_data_storage) = { 23 .bh_lock = INIT_LOCAL_LOCK(bh_lock), 24 }; 25 26 static int sch_frag_xmit(struct net *net, struct sock *sk, struct sk_buff *skb) 27 { 28 struct sch_frag_data *data = this_cpu_ptr(&sch_frag_data_storage); 29 30 lockdep_assert_held(&data->bh_lock); 31 if (skb_cow_head(skb, data->l2_len) < 0) { 32 kfree_skb(skb); 33 return -ENOMEM; 34 } 35 36 __skb_dst_copy(skb, data->dst); 37 *qdisc_skb_cb(skb) = data->cb; 38 skb->inner_protocol = data->inner_protocol; 39 if (data->vlan_tci & VLAN_CFI_MASK) 40 __vlan_hwaccel_put_tag(skb, data->vlan_proto, 41 data->vlan_tci & ~VLAN_CFI_MASK); 42 else 43 __vlan_hwaccel_clear_tag(skb); 44 45 /* Reconstruct the MAC header. */ 46 skb_push(skb, data->l2_len); 47 memcpy(skb->data, &data->l2_data, data->l2_len); 48 skb_postpush_rcsum(skb, skb->data, data->l2_len); 49 skb_reset_mac_header(skb); 50 51 return data->xmit(skb); 52 } 53 54 static void sch_frag_prepare_frag(struct sk_buff *skb, 55 int (*xmit)(struct sk_buff *skb)) 56 { 57 unsigned int hlen = skb_network_offset(skb); 58 struct sch_frag_data *data; 59 60 data = this_cpu_ptr(&sch_frag_data_storage); 61 data->dst = skb->_skb_refdst; 62 data->cb = *qdisc_skb_cb(skb); 63 data->xmit = xmit; 64 data->inner_protocol = skb->inner_protocol; 65 if (skb_vlan_tag_present(skb)) 66 data->vlan_tci = skb_vlan_tag_get(skb) | VLAN_CFI_MASK; 67 else 68 data->vlan_tci = 0; 69 data->vlan_proto = skb->vlan_proto; 70 data->l2_len = hlen; 71 memcpy(&data->l2_data, skb->data, hlen); 72 73 memset(IPCB(skb), 0, sizeof(struct inet_skb_parm)); 74 skb_pull(skb, hlen); 75 } 76 77 static unsigned int 78 sch_frag_dst_get_mtu(const struct dst_entry *dst) 79 { 80 return dst->dev->mtu; 81 } 82 83 static struct dst_ops sch_frag_dst_ops = { 84 .family = AF_UNSPEC, 85 .mtu = sch_frag_dst_get_mtu, 86 }; 87 88 static int sch_fragment(struct net *net, struct sk_buff *skb, 89 u16 mru, int (*xmit)(struct sk_buff *skb)) 90 { 91 int ret = -1; 92 93 if (skb_network_offset(skb) > VLAN_ETH_HLEN) { 94 net_warn_ratelimited("L2 header too long to fragment\n"); 95 goto err; 96 } 97 98 if (skb_protocol(skb, true) == htons(ETH_P_IP)) { 99 struct rtable sch_frag_rt = { 0 }; 100 unsigned long orig_dst; 101 102 local_lock_nested_bh(&sch_frag_data_storage.bh_lock); 103 sch_frag_prepare_frag(skb, xmit); 104 dst_init(&sch_frag_rt.dst, &sch_frag_dst_ops, NULL, 105 DST_OBSOLETE_NONE, DST_NOCOUNT); 106 sch_frag_rt.dst.dev = skb->dev; 107 108 orig_dst = skb->_skb_refdst; 109 skb_dst_set_noref(skb, &sch_frag_rt.dst); 110 IPCB(skb)->frag_max_size = mru; 111 112 ret = ip_do_fragment(net, skb->sk, skb, sch_frag_xmit); 113 local_unlock_nested_bh(&sch_frag_data_storage.bh_lock); 114 refdst_drop(orig_dst); 115 } else if (skb_protocol(skb, true) == htons(ETH_P_IPV6)) { 116 unsigned long orig_dst; 117 struct rt6_info sch_frag_rt; 118 119 local_lock_nested_bh(&sch_frag_data_storage.bh_lock); 120 sch_frag_prepare_frag(skb, xmit); 121 memset(&sch_frag_rt, 0, sizeof(sch_frag_rt)); 122 dst_init(&sch_frag_rt.dst, &sch_frag_dst_ops, NULL, 123 DST_OBSOLETE_NONE, DST_NOCOUNT); 124 sch_frag_rt.dst.dev = skb->dev; 125 126 orig_dst = skb->_skb_refdst; 127 skb_dst_set_noref(skb, &sch_frag_rt.dst); 128 IP6CB(skb)->frag_max_size = mru; 129 130 ret = ipv6_stub->ipv6_fragment(net, skb->sk, skb, 131 sch_frag_xmit); 132 local_unlock_nested_bh(&sch_frag_data_storage.bh_lock); 133 refdst_drop(orig_dst); 134 } else { 135 net_warn_ratelimited("Fail frag %s: eth=%x, MRU=%d, MTU=%d\n", 136 netdev_name(skb->dev), 137 ntohs(skb_protocol(skb, true)), mru, 138 skb->dev->mtu); 139 goto err; 140 } 141 142 return ret; 143 err: 144 kfree_skb(skb); 145 return ret; 146 } 147 148 int sch_frag_xmit_hook(struct sk_buff *skb, int (*xmit)(struct sk_buff *skb)) 149 { 150 u16 mru = tc_skb_cb(skb)->mru; 151 int err; 152 153 if (mru && skb->len > mru + skb->dev->hard_header_len) 154 err = sch_fragment(dev_net(skb->dev), skb, mru, xmit); 155 else 156 err = xmit(skb); 157 158 return err; 159 } 160 EXPORT_SYMBOL_GPL(sch_frag_xmit_hook); 161