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
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