1/*
2 *	IPV4 GSO/GRO offload support
3 *	Linux INET implementation
4 *
5 *	This program is free software; you can redistribute it and/or
6 *	modify it under the terms of the GNU General Public License
7 *	as published by the Free Software Foundation; either version
8 *	2 of the License, or (at your option) any later version.
9 *
10 *	UDPv4 GSO support
11 */
12
13#include <linux/skbuff.h>
14#include <net/udp.h>
15#include <net/protocol.h>
16
17static DEFINE_SPINLOCK(udp_offload_lock);
18static struct udp_offload_priv __rcu *udp_offload_base __read_mostly;
19
20#define udp_deref_protected(X) rcu_dereference_protected(X, lockdep_is_held(&udp_offload_lock))
21
22struct udp_offload_priv {
23	struct udp_offload	*offload;
24	struct rcu_head		rcu;
25	struct udp_offload_priv __rcu *next;
26};
27
28static struct sk_buff *__skb_udp_tunnel_segment(struct sk_buff *skb,
29	netdev_features_t features,
30	struct sk_buff *(*gso_inner_segment)(struct sk_buff *skb,
31					     netdev_features_t features),
32	__be16 new_protocol, bool is_ipv6)
33{
34	struct sk_buff *segs = ERR_PTR(-EINVAL);
35	u16 mac_offset = skb->mac_header;
36	int mac_len = skb->mac_len;
37	int tnl_hlen = skb_inner_mac_header(skb) - skb_transport_header(skb);
38	__be16 protocol = skb->protocol;
39	netdev_features_t enc_features;
40	int udp_offset, outer_hlen;
41	unsigned int oldlen;
42	bool need_csum = !!(skb_shinfo(skb)->gso_type &
43			    SKB_GSO_UDP_TUNNEL_CSUM);
44	bool remcsum = !!(skb_shinfo(skb)->gso_type & SKB_GSO_TUNNEL_REMCSUM);
45	bool offload_csum = false, dont_encap = (need_csum || remcsum);
46
47	oldlen = (u16)~skb->len;
48
49	if (unlikely(!pskb_may_pull(skb, tnl_hlen)))
50		goto out;
51
52	skb->encapsulation = 0;
53	__skb_pull(skb, tnl_hlen);
54	skb_reset_mac_header(skb);
55	skb_set_network_header(skb, skb_inner_network_offset(skb));
56	skb->mac_len = skb_inner_network_offset(skb);
57	skb->protocol = new_protocol;
58	skb->encap_hdr_csum = need_csum;
59	skb->remcsum_offload = remcsum;
60
61	/* Try to offload checksum if possible */
62	offload_csum = !!(need_csum &&
63			  (skb->dev->features &
64			   (is_ipv6 ? NETIF_F_V6_CSUM : NETIF_F_V4_CSUM)));
65
66	/* segment inner packet. */
67	enc_features = skb->dev->hw_enc_features & features;
68	segs = gso_inner_segment(skb, enc_features);
69	if (IS_ERR_OR_NULL(segs)) {
70		skb_gso_error_unwind(skb, protocol, tnl_hlen, mac_offset,
71				     mac_len);
72		goto out;
73	}
74
75	outer_hlen = skb_tnl_header_len(skb);
76	udp_offset = outer_hlen - tnl_hlen;
77	skb = segs;
78	do {
79		struct udphdr *uh;
80		int len;
81		__be32 delta;
82
83		if (dont_encap) {
84			skb->encapsulation = 0;
85			skb->ip_summed = CHECKSUM_NONE;
86		} else {
87			/* Only set up inner headers if we might be offloading
88			 * inner checksum.
89			 */
90			skb_reset_inner_headers(skb);
91			skb->encapsulation = 1;
92		}
93
94		skb->mac_len = mac_len;
95		skb->protocol = protocol;
96
97		skb_push(skb, outer_hlen);
98		skb_reset_mac_header(skb);
99		skb_set_network_header(skb, mac_len);
100		skb_set_transport_header(skb, udp_offset);
101		len = skb->len - udp_offset;
102		uh = udp_hdr(skb);
103		uh->len = htons(len);
104
105		if (!need_csum)
106			continue;
107
108		delta = htonl(oldlen + len);
109
110		uh->check = ~csum_fold((__force __wsum)
111				       ((__force u32)uh->check +
112					(__force u32)delta));
113		if (offload_csum) {
114			skb->ip_summed = CHECKSUM_PARTIAL;
115			skb->csum_start = skb_transport_header(skb) - skb->head;
116			skb->csum_offset = offsetof(struct udphdr, check);
117		} else if (remcsum) {
118			/* Need to calculate checksum from scratch,
119			 * inner checksums are never when doing
120			 * remote_checksum_offload.
121			 */
122
123			skb->csum = skb_checksum(skb, udp_offset,
124						 skb->len - udp_offset,
125						 0);
126			uh->check = csum_fold(skb->csum);
127			if (uh->check == 0)
128				uh->check = CSUM_MANGLED_0;
129		} else {
130			uh->check = gso_make_checksum(skb, ~uh->check);
131
132			if (uh->check == 0)
133				uh->check = CSUM_MANGLED_0;
134		}
135	} while ((skb = skb->next));
136out:
137	return segs;
138}
139
140struct sk_buff *skb_udp_tunnel_segment(struct sk_buff *skb,
141				       netdev_features_t features,
142				       bool is_ipv6)
143{
144	__be16 protocol = skb->protocol;
145	const struct net_offload **offloads;
146	const struct net_offload *ops;
147	struct sk_buff *segs = ERR_PTR(-EINVAL);
148	struct sk_buff *(*gso_inner_segment)(struct sk_buff *skb,
149					     netdev_features_t features);
150
151	rcu_read_lock();
152
153	switch (skb->inner_protocol_type) {
154	case ENCAP_TYPE_ETHER:
155		protocol = skb->inner_protocol;
156		gso_inner_segment = skb_mac_gso_segment;
157		break;
158	case ENCAP_TYPE_IPPROTO:
159		offloads = is_ipv6 ? inet6_offloads : inet_offloads;
160		ops = rcu_dereference(offloads[skb->inner_ipproto]);
161		if (!ops || !ops->callbacks.gso_segment)
162			goto out_unlock;
163		gso_inner_segment = ops->callbacks.gso_segment;
164		break;
165	default:
166		goto out_unlock;
167	}
168
169	segs = __skb_udp_tunnel_segment(skb, features, gso_inner_segment,
170					protocol, is_ipv6);
171
172out_unlock:
173	rcu_read_unlock();
174
175	return segs;
176}
177
178static struct sk_buff *udp4_ufo_fragment(struct sk_buff *skb,
179					 netdev_features_t features)
180{
181	struct sk_buff *segs = ERR_PTR(-EINVAL);
182	unsigned int mss;
183	__wsum csum;
184	struct udphdr *uh;
185	struct iphdr *iph;
186
187	if (skb->encapsulation &&
188	    (skb_shinfo(skb)->gso_type &
189	     (SKB_GSO_UDP_TUNNEL|SKB_GSO_UDP_TUNNEL_CSUM))) {
190		segs = skb_udp_tunnel_segment(skb, features, false);
191		goto out;
192	}
193
194	if (!pskb_may_pull(skb, sizeof(struct udphdr)))
195		goto out;
196
197	mss = skb_shinfo(skb)->gso_size;
198	if (unlikely(skb->len <= mss))
199		goto out;
200
201	if (skb_gso_ok(skb, features | NETIF_F_GSO_ROBUST)) {
202		/* Packet is from an untrusted source, reset gso_segs. */
203		int type = skb_shinfo(skb)->gso_type;
204
205		if (unlikely(type & ~(SKB_GSO_UDP | SKB_GSO_DODGY |
206				      SKB_GSO_UDP_TUNNEL |
207				      SKB_GSO_UDP_TUNNEL_CSUM |
208				      SKB_GSO_TUNNEL_REMCSUM |
209				      SKB_GSO_IPIP |
210				      SKB_GSO_GRE | SKB_GSO_GRE_CSUM) ||
211			     !(type & (SKB_GSO_UDP))))
212			goto out;
213
214		skb_shinfo(skb)->gso_segs = DIV_ROUND_UP(skb->len, mss);
215
216		segs = NULL;
217		goto out;
218	}
219
220	/* Do software UFO. Complete and fill in the UDP checksum as
221	 * HW cannot do checksum of UDP packets sent as multiple
222	 * IP fragments.
223	 */
224
225	uh = udp_hdr(skb);
226	iph = ip_hdr(skb);
227
228	uh->check = 0;
229	csum = skb_checksum(skb, 0, skb->len, 0);
230	uh->check = udp_v4_check(skb->len, iph->saddr, iph->daddr, csum);
231	if (uh->check == 0)
232		uh->check = CSUM_MANGLED_0;
233
234	skb->ip_summed = CHECKSUM_NONE;
235
236	/* Fragment the skb. IP headers of the fragments are updated in
237	 * inet_gso_segment()
238	 */
239	segs = skb_segment(skb, features);
240out:
241	return segs;
242}
243
244int udp_add_offload(struct udp_offload *uo)
245{
246	struct udp_offload_priv *new_offload = kzalloc(sizeof(*new_offload), GFP_ATOMIC);
247
248	if (!new_offload)
249		return -ENOMEM;
250
251	new_offload->offload = uo;
252
253	spin_lock(&udp_offload_lock);
254	new_offload->next = udp_offload_base;
255	rcu_assign_pointer(udp_offload_base, new_offload);
256	spin_unlock(&udp_offload_lock);
257
258	return 0;
259}
260EXPORT_SYMBOL(udp_add_offload);
261
262static void udp_offload_free_routine(struct rcu_head *head)
263{
264	struct udp_offload_priv *ou_priv = container_of(head, struct udp_offload_priv, rcu);
265	kfree(ou_priv);
266}
267
268void udp_del_offload(struct udp_offload *uo)
269{
270	struct udp_offload_priv __rcu **head = &udp_offload_base;
271	struct udp_offload_priv *uo_priv;
272
273	spin_lock(&udp_offload_lock);
274
275	uo_priv = udp_deref_protected(*head);
276	for (; uo_priv != NULL;
277	     uo_priv = udp_deref_protected(*head)) {
278		if (uo_priv->offload == uo) {
279			rcu_assign_pointer(*head,
280					   udp_deref_protected(uo_priv->next));
281			goto unlock;
282		}
283		head = &uo_priv->next;
284	}
285	pr_warn("udp_del_offload: didn't find offload for port %d\n", ntohs(uo->port));
286unlock:
287	spin_unlock(&udp_offload_lock);
288	if (uo_priv)
289		call_rcu(&uo_priv->rcu, udp_offload_free_routine);
290}
291EXPORT_SYMBOL(udp_del_offload);
292
293struct sk_buff **udp_gro_receive(struct sk_buff **head, struct sk_buff *skb,
294				 struct udphdr *uh)
295{
296	struct udp_offload_priv *uo_priv;
297	struct sk_buff *p, **pp = NULL;
298	struct udphdr *uh2;
299	unsigned int off = skb_gro_offset(skb);
300	int flush = 1;
301
302	if (NAPI_GRO_CB(skb)->udp_mark ||
303	    (skb->ip_summed != CHECKSUM_PARTIAL &&
304	     NAPI_GRO_CB(skb)->csum_cnt == 0 &&
305	     !NAPI_GRO_CB(skb)->csum_valid))
306		goto out;
307
308	/* mark that this skb passed once through the udp gro layer */
309	NAPI_GRO_CB(skb)->udp_mark = 1;
310
311	rcu_read_lock();
312	uo_priv = rcu_dereference(udp_offload_base);
313	for (; uo_priv != NULL; uo_priv = rcu_dereference(uo_priv->next)) {
314		if (uo_priv->offload->port == uh->dest &&
315		    uo_priv->offload->callbacks.gro_receive)
316			goto unflush;
317	}
318	goto out_unlock;
319
320unflush:
321	flush = 0;
322
323	for (p = *head; p; p = p->next) {
324		if (!NAPI_GRO_CB(p)->same_flow)
325			continue;
326
327		uh2 = (struct udphdr   *)(p->data + off);
328
329		/* Match ports and either checksums are either both zero
330		 * or nonzero.
331		 */
332		if ((*(u32 *)&uh->source != *(u32 *)&uh2->source) ||
333		    (!uh->check ^ !uh2->check)) {
334			NAPI_GRO_CB(p)->same_flow = 0;
335			continue;
336		}
337	}
338
339	skb_gro_pull(skb, sizeof(struct udphdr)); /* pull encapsulating udp header */
340	skb_gro_postpull_rcsum(skb, uh, sizeof(struct udphdr));
341	NAPI_GRO_CB(skb)->proto = uo_priv->offload->ipproto;
342	pp = uo_priv->offload->callbacks.gro_receive(head, skb,
343						     uo_priv->offload);
344
345out_unlock:
346	rcu_read_unlock();
347out:
348	NAPI_GRO_CB(skb)->flush |= flush;
349	return pp;
350}
351
352static struct sk_buff **udp4_gro_receive(struct sk_buff **head,
353					 struct sk_buff *skb)
354{
355	struct udphdr *uh = udp_gro_udphdr(skb);
356
357	if (unlikely(!uh))
358		goto flush;
359
360	/* Don't bother verifying checksum if we're going to flush anyway. */
361	if (NAPI_GRO_CB(skb)->flush)
362		goto skip;
363
364	if (skb_gro_checksum_validate_zero_check(skb, IPPROTO_UDP, uh->check,
365						 inet_gro_compute_pseudo))
366		goto flush;
367	else if (uh->check)
368		skb_gro_checksum_try_convert(skb, IPPROTO_UDP, uh->check,
369					     inet_gro_compute_pseudo);
370skip:
371	NAPI_GRO_CB(skb)->is_ipv6 = 0;
372	return udp_gro_receive(head, skb, uh);
373
374flush:
375	NAPI_GRO_CB(skb)->flush = 1;
376	return NULL;
377}
378
379int udp_gro_complete(struct sk_buff *skb, int nhoff)
380{
381	struct udp_offload_priv *uo_priv;
382	__be16 newlen = htons(skb->len - nhoff);
383	struct udphdr *uh = (struct udphdr *)(skb->data + nhoff);
384	int err = -ENOSYS;
385
386	uh->len = newlen;
387
388	rcu_read_lock();
389
390	uo_priv = rcu_dereference(udp_offload_base);
391	for (; uo_priv != NULL; uo_priv = rcu_dereference(uo_priv->next)) {
392		if (uo_priv->offload->port == uh->dest &&
393		    uo_priv->offload->callbacks.gro_complete)
394			break;
395	}
396
397	if (uo_priv) {
398		NAPI_GRO_CB(skb)->proto = uo_priv->offload->ipproto;
399		err = uo_priv->offload->callbacks.gro_complete(skb,
400				nhoff + sizeof(struct udphdr),
401				uo_priv->offload);
402	}
403
404	rcu_read_unlock();
405
406	if (skb->remcsum_offload)
407		skb_shinfo(skb)->gso_type |= SKB_GSO_TUNNEL_REMCSUM;
408
409	skb->encapsulation = 1;
410	skb_set_inner_mac_header(skb, nhoff + sizeof(struct udphdr));
411
412	return err;
413}
414
415static int udp4_gro_complete(struct sk_buff *skb, int nhoff)
416{
417	const struct iphdr *iph = ip_hdr(skb);
418	struct udphdr *uh = (struct udphdr *)(skb->data + nhoff);
419
420	if (uh->check) {
421		skb_shinfo(skb)->gso_type |= SKB_GSO_UDP_TUNNEL_CSUM;
422		uh->check = ~udp_v4_check(skb->len - nhoff, iph->saddr,
423					  iph->daddr, 0);
424	} else {
425		skb_shinfo(skb)->gso_type |= SKB_GSO_UDP_TUNNEL;
426	}
427
428	return udp_gro_complete(skb, nhoff);
429}
430
431static const struct net_offload udpv4_offload = {
432	.callbacks = {
433		.gso_segment = udp4_ufo_fragment,
434		.gro_receive  =	udp4_gro_receive,
435		.gro_complete =	udp4_gro_complete,
436	},
437};
438
439int __init udpv4_offload_init(void)
440{
441	return inet_add_offload(&udpv4_offload, IPPROTO_UDP);
442}
443