xref: /openbmc/linux/net/sched/sch_frag.c (revision b6459415)
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 
sch_frag_xmit(struct net * net,struct sock * sk,struct sk_buff * skb)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 
sch_frag_prepare_frag(struct sk_buff * skb,int (* xmit)(struct sk_buff * skb))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
sch_frag_dst_get_mtu(const struct dst_entry * dst)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 
sch_fragment(struct net * net,struct sk_buff * skb,u16 mru,int (* xmit)(struct sk_buff * skb))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 
sch_frag_xmit_hook(struct sk_buff * skb,int (* xmit)(struct sk_buff * skb))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