xref: /openbmc/linux/net/xfrm/xfrm_device.c (revision 8d81cd1a) 
1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3  * xfrm_device.c - IPsec device offloading code.
4  *
5  * Copyright (c) 2015 secunet Security Networks AG
6  *
7  * Author:
8  * Steffen Klassert <steffen.klassert@secunet.com>
9  */
10 
11 #include <linux/errno.h>
12 #include <linux/module.h>
13 #include <linux/netdevice.h>
14 #include <linux/skbuff.h>
15 #include <linux/slab.h>
16 #include <linux/spinlock.h>
17 #include <net/dst.h>
18 #include <net/gso.h>
19 #include <net/xfrm.h>
20 #include <linux/notifier.h>
21 
22 #ifdef CONFIG_XFRM_OFFLOAD
23 static void __xfrm_transport_prep(struct xfrm_state *x, struct sk_buff *skb,
24 				  unsigned int hsize)
25 {
26 	struct xfrm_offload *xo = xfrm_offload(skb);
27 
28 	skb_reset_mac_len(skb);
29 	if (xo->flags & XFRM_GSO_SEGMENT)
30 		skb->transport_header -= x->props.header_len;
31 
32 	pskb_pull(skb, skb_transport_offset(skb) + x->props.header_len);
33 }
34 
35 static void __xfrm_mode_tunnel_prep(struct xfrm_state *x, struct sk_buff *skb,
36 				    unsigned int hsize)
37 
38 {
39 	struct xfrm_offload *xo = xfrm_offload(skb);
40 
41 	if (xo->flags & XFRM_GSO_SEGMENT)
42 		skb->transport_header = skb->network_header + hsize;
43 
44 	skb_reset_mac_len(skb);
45 	pskb_pull(skb, skb->mac_len + x->props.header_len);
46 }
47 
48 static void __xfrm_mode_beet_prep(struct xfrm_state *x, struct sk_buff *skb,
49 				  unsigned int hsize)
50 {
51 	struct xfrm_offload *xo = xfrm_offload(skb);
52 	int phlen = 0;
53 
54 	if (xo->flags & XFRM_GSO_SEGMENT)
55 		skb->transport_header = skb->network_header + hsize;
56 
57 	skb_reset_mac_len(skb);
58 	if (x->sel.family != AF_INET6) {
59 		phlen = IPV4_BEET_PHMAXLEN;
60 		if (x->outer_mode.family == AF_INET6)
61 			phlen += sizeof(struct ipv6hdr) - sizeof(struct iphdr);
62 	}
63 
64 	pskb_pull(skb, skb->mac_len + hsize + (x->props.header_len - phlen));
65 }
66 
67 /* Adjust pointers into the packet when IPsec is done at layer2 */
68 static void xfrm_outer_mode_prep(struct xfrm_state *x, struct sk_buff *skb)
69 {
70 	switch (x->outer_mode.encap) {
71 	case XFRM_MODE_TUNNEL:
72 		if (x->outer_mode.family == AF_INET)
73 			return __xfrm_mode_tunnel_prep(x, skb,
74 						       sizeof(struct iphdr));
75 		if (x->outer_mode.family == AF_INET6)
76 			return __xfrm_mode_tunnel_prep(x, skb,
77 						       sizeof(struct ipv6hdr));
78 		break;
79 	case XFRM_MODE_TRANSPORT:
80 		if (x->outer_mode.family == AF_INET)
81 			return __xfrm_transport_prep(x, skb,
82 						     sizeof(struct iphdr));
83 		if (x->outer_mode.family == AF_INET6)
84 			return __xfrm_transport_prep(x, skb,
85 						     sizeof(struct ipv6hdr));
86 		break;
87 	case XFRM_MODE_BEET:
88 		if (x->outer_mode.family == AF_INET)
89 			return __xfrm_mode_beet_prep(x, skb,
90 						     sizeof(struct iphdr));
91 		if (x->outer_mode.family == AF_INET6)
92 			return __xfrm_mode_beet_prep(x, skb,
93 						     sizeof(struct ipv6hdr));
94 		break;
95 	case XFRM_MODE_ROUTEOPTIMIZATION:
96 	case XFRM_MODE_IN_TRIGGER:
97 		break;
98 	}
99 }
100 
101 static inline bool xmit_xfrm_check_overflow(struct sk_buff *skb)
102 {
103 	struct xfrm_offload *xo = xfrm_offload(skb);
104 	__u32 seq = xo->seq.low;
105 
106 	seq += skb_shinfo(skb)->gso_segs;
107 	if (unlikely(seq < xo->seq.low))
108 		return true;
109 
110 	return false;
111 }
112 
113 struct sk_buff *validate_xmit_xfrm(struct sk_buff *skb, netdev_features_t features, bool *again)
114 {
115 	int err;
116 	unsigned long flags;
117 	struct xfrm_state *x;
118 	struct softnet_data *sd;
119 	struct sk_buff *skb2, *nskb, *pskb = NULL;
120 	netdev_features_t esp_features = features;
121 	struct xfrm_offload *xo = xfrm_offload(skb);
122 	struct net_device *dev = skb->dev;
123 	struct sec_path *sp;
124 
125 	if (!xo || (xo->flags & XFRM_XMIT))
126 		return skb;
127 
128 	if (!(features & NETIF_F_HW_ESP))
129 		esp_features = features & ~(NETIF_F_SG | NETIF_F_CSUM_MASK);
130 
131 	sp = skb_sec_path(skb);
132 	x = sp->xvec[sp->len - 1];
133 	if (xo->flags & XFRM_GRO || x->xso.dir == XFRM_DEV_OFFLOAD_IN)
134 		return skb;
135 
136 	/* The packet was sent to HW IPsec packet offload engine,
137 	 * but to wrong device. Drop the packet, so it won't skip
138 	 * XFRM stack.
139 	 */
140 	if (x->xso.type == XFRM_DEV_OFFLOAD_PACKET && x->xso.dev != dev) {
141 		kfree_skb(skb);
142 		dev_core_stats_tx_dropped_inc(dev);
143 		return NULL;
144 	}
145 
146 	/* This skb was already validated on the upper/virtual dev */
147 	if ((x->xso.dev != dev) && (x->xso.real_dev == dev))
148 		return skb;
149 
150 	local_irq_save(flags);
151 	sd = this_cpu_ptr(&softnet_data);
152 	err = !skb_queue_empty(&sd->xfrm_backlog);
153 	local_irq_restore(flags);
154 
155 	if (err) {
156 		*again = true;
157 		return skb;
158 	}
159 
160 	if (skb_is_gso(skb) && (unlikely(x->xso.dev != dev) ||
161 				unlikely(xmit_xfrm_check_overflow(skb)))) {
162 		struct sk_buff *segs;
163 
164 		/* Packet got rerouted, fixup features and segment it. */
165 		esp_features = esp_features & ~(NETIF_F_HW_ESP | NETIF_F_GSO_ESP);
166 
167 		segs = skb_gso_segment(skb, esp_features);
168 		if (IS_ERR(segs)) {
169 			kfree_skb(skb);
170 			dev_core_stats_tx_dropped_inc(dev);
171 			return NULL;
172 		} else {
173 			consume_skb(skb);
174 			skb = segs;
175 		}
176 	}
177 
178 	if (!skb->next) {
179 		esp_features |= skb->dev->gso_partial_features;
180 		xfrm_outer_mode_prep(x, skb);
181 
182 		xo->flags |= XFRM_DEV_RESUME;
183 
184 		err = x->type_offload->xmit(x, skb, esp_features);
185 		if (err) {
186 			if (err == -EINPROGRESS)
187 				return NULL;
188 
189 			XFRM_INC_STATS(xs_net(x), LINUX_MIB_XFRMOUTSTATEPROTOERROR);
190 			kfree_skb(skb);
191 			return NULL;
192 		}
193 
194 		skb_push(skb, skb->data - skb_mac_header(skb));
195 
196 		return skb;
197 	}
198 
199 	skb_list_walk_safe(skb, skb2, nskb) {
200 		esp_features |= skb->dev->gso_partial_features;
201 		skb_mark_not_on_list(skb2);
202 
203 		xo = xfrm_offload(skb2);
204 		xo->flags |= XFRM_DEV_RESUME;
205 
206 		xfrm_outer_mode_prep(x, skb2);
207 
208 		err = x->type_offload->xmit(x, skb2, esp_features);
209 		if (!err) {
210 			skb2->next = nskb;
211 		} else if (err != -EINPROGRESS) {
212 			XFRM_INC_STATS(xs_net(x), LINUX_MIB_XFRMOUTSTATEPROTOERROR);
213 			skb2->next = nskb;
214 			kfree_skb_list(skb2);
215 			return NULL;
216 		} else {
217 			if (skb == skb2)
218 				skb = nskb;
219 			else
220 				pskb->next = nskb;
221 
222 			continue;
223 		}
224 
225 		skb_push(skb2, skb2->data - skb_mac_header(skb2));
226 		pskb = skb2;
227 	}
228 
229 	return skb;
230 }
231 EXPORT_SYMBOL_GPL(validate_xmit_xfrm);
232 
233 int xfrm_dev_state_add(struct net *net, struct xfrm_state *x,
234 		       struct xfrm_user_offload *xuo,
235 		       struct netlink_ext_ack *extack)
236 {
237 	int err;
238 	struct dst_entry *dst;
239 	struct net_device *dev;
240 	struct xfrm_dev_offload *xso = &x->xso;
241 	xfrm_address_t *saddr;
242 	xfrm_address_t *daddr;
243 	bool is_packet_offload;
244 
245 	if (!x->type_offload) {
246 		NL_SET_ERR_MSG(extack, "Type doesn't support offload");
247 		return -EINVAL;
248 	}
249 
250 	if (xuo->flags &
251 	    ~(XFRM_OFFLOAD_IPV6 | XFRM_OFFLOAD_INBOUND | XFRM_OFFLOAD_PACKET)) {
252 		NL_SET_ERR_MSG(extack, "Unrecognized flags in offload request");
253 		return -EINVAL;
254 	}
255 
256 	is_packet_offload = xuo->flags & XFRM_OFFLOAD_PACKET;
257 
258 	/* We don't yet support UDP encapsulation and TFC padding. */
259 	if ((!is_packet_offload && x->encap) || x->tfcpad) {
260 		NL_SET_ERR_MSG(extack, "Encapsulation and TFC padding can't be offloaded");
261 		return -EINVAL;
262 	}
263 
264 	dev = dev_get_by_index(net, xuo->ifindex);
265 	if (!dev) {
266 		if (!(xuo->flags & XFRM_OFFLOAD_INBOUND)) {
267 			saddr = &x->props.saddr;
268 			daddr = &x->id.daddr;
269 		} else {
270 			saddr = &x->id.daddr;
271 			daddr = &x->props.saddr;
272 		}
273 
274 		dst = __xfrm_dst_lookup(net, 0, 0, saddr, daddr,
275 					x->props.family,
276 					xfrm_smark_get(0, x));
277 		if (IS_ERR(dst))
278 			return (is_packet_offload) ? -EINVAL : 0;
279 
280 		dev = dst->dev;
281 
282 		dev_hold(dev);
283 		dst_release(dst);
284 	}
285 
286 	if (!dev->xfrmdev_ops || !dev->xfrmdev_ops->xdo_dev_state_add) {
287 		xso->dev = NULL;
288 		dev_put(dev);
289 		return (is_packet_offload) ? -EINVAL : 0;
290 	}
291 
292 	if (!is_packet_offload && x->props.flags & XFRM_STATE_ESN &&
293 	    !dev->xfrmdev_ops->xdo_dev_state_advance_esn) {
294 		NL_SET_ERR_MSG(extack, "Device doesn't support offload with ESN");
295 		xso->dev = NULL;
296 		dev_put(dev);
297 		return -EINVAL;
298 	}
299 
300 	xso->dev = dev;
301 	netdev_tracker_alloc(dev, &xso->dev_tracker, GFP_ATOMIC);
302 	xso->real_dev = dev;
303 
304 	if (xuo->flags & XFRM_OFFLOAD_INBOUND)
305 		xso->dir = XFRM_DEV_OFFLOAD_IN;
306 	else
307 		xso->dir = XFRM_DEV_OFFLOAD_OUT;
308 
309 	if (is_packet_offload)
310 		xso->type = XFRM_DEV_OFFLOAD_PACKET;
311 	else
312 		xso->type = XFRM_DEV_OFFLOAD_CRYPTO;
313 
314 	err = dev->xfrmdev_ops->xdo_dev_state_add(x, extack);
315 	if (err) {
316 		xso->dev = NULL;
317 		xso->dir = 0;
318 		xso->real_dev = NULL;
319 		netdev_put(dev, &xso->dev_tracker);
320 		xso->type = XFRM_DEV_OFFLOAD_UNSPECIFIED;
321 
322 		/* User explicitly requested packet offload mode and configured
323 		 * policy in addition to the XFRM state. So be civil to users,
324 		 * and return an error instead of taking fallback path.
325 		 *
326 		 * This WARN_ON() can be seen as a documentation for driver
327 		 * authors to do not return -EOPNOTSUPP in packet offload mode.
328 		 */
329 		WARN_ON(err == -EOPNOTSUPP && is_packet_offload);
330 		if (err != -EOPNOTSUPP || is_packet_offload) {
331 			NL_SET_ERR_MSG_WEAK(extack, "Device failed to offload this state");
332 			return err;
333 		}
334 	}
335 
336 	return 0;
337 }
338 EXPORT_SYMBOL_GPL(xfrm_dev_state_add);
339 
340 int xfrm_dev_policy_add(struct net *net, struct xfrm_policy *xp,
341 			struct xfrm_user_offload *xuo, u8 dir,
342 			struct netlink_ext_ack *extack)
343 {
344 	struct xfrm_dev_offload *xdo = &xp->xdo;
345 	struct net_device *dev;
346 	int err;
347 
348 	if (!xuo->flags || xuo->flags & ~XFRM_OFFLOAD_PACKET) {
349 		/* We support only packet offload mode and it means
350 		 * that user must set XFRM_OFFLOAD_PACKET bit.
351 		 */
352 		NL_SET_ERR_MSG(extack, "Unrecognized flags in offload request");
353 		return -EINVAL;
354 	}
355 
356 	dev = dev_get_by_index(net, xuo->ifindex);
357 	if (!dev)
358 		return -EINVAL;
359 
360 	if (!dev->xfrmdev_ops || !dev->xfrmdev_ops->xdo_dev_policy_add) {
361 		xdo->dev = NULL;
362 		dev_put(dev);
363 		NL_SET_ERR_MSG(extack, "Policy offload is not supported");
364 		return -EINVAL;
365 	}
366 
367 	xdo->dev = dev;
368 	netdev_tracker_alloc(dev, &xdo->dev_tracker, GFP_ATOMIC);
369 	xdo->real_dev = dev;
370 	xdo->type = XFRM_DEV_OFFLOAD_PACKET;
371 	switch (dir) {
372 	case XFRM_POLICY_IN:
373 		xdo->dir = XFRM_DEV_OFFLOAD_IN;
374 		break;
375 	case XFRM_POLICY_OUT:
376 		xdo->dir = XFRM_DEV_OFFLOAD_OUT;
377 		break;
378 	case XFRM_POLICY_FWD:
379 		xdo->dir = XFRM_DEV_OFFLOAD_FWD;
380 		break;
381 	default:
382 		xdo->dev = NULL;
383 		netdev_put(dev, &xdo->dev_tracker);
384 		NL_SET_ERR_MSG(extack, "Unrecognized offload direction");
385 		return -EINVAL;
386 	}
387 
388 	err = dev->xfrmdev_ops->xdo_dev_policy_add(xp, extack);
389 	if (err) {
390 		xdo->dev = NULL;
391 		xdo->real_dev = NULL;
392 		xdo->type = XFRM_DEV_OFFLOAD_UNSPECIFIED;
393 		xdo->dir = 0;
394 		netdev_put(dev, &xdo->dev_tracker);
395 		NL_SET_ERR_MSG_WEAK(extack, "Device failed to offload this policy");
396 		return err;
397 	}
398 
399 	return 0;
400 }
401 EXPORT_SYMBOL_GPL(xfrm_dev_policy_add);
402 
403 bool xfrm_dev_offload_ok(struct sk_buff *skb, struct xfrm_state *x)
404 {
405 	int mtu;
406 	struct dst_entry *dst = skb_dst(skb);
407 	struct xfrm_dst *xdst = (struct xfrm_dst *)dst;
408 	struct net_device *dev = x->xso.dev;
409 
410 	if (!x->type_offload ||
411 	    (x->xso.type == XFRM_DEV_OFFLOAD_UNSPECIFIED && x->encap))
412 		return false;
413 
414 	if (x->xso.type == XFRM_DEV_OFFLOAD_PACKET ||
415 	    ((!dev || (dev == xfrm_dst_path(dst)->dev)) &&
416 	     !xdst->child->xfrm)) {
417 		mtu = xfrm_state_mtu(x, xdst->child_mtu_cached);
418 		if (skb->len <= mtu)
419 			goto ok;
420 
421 		if (skb_is_gso(skb) && skb_gso_validate_network_len(skb, mtu))
422 			goto ok;
423 	}
424 
425 	return false;
426 
427 ok:
428 	if (dev && dev->xfrmdev_ops && dev->xfrmdev_ops->xdo_dev_offload_ok)
429 		return x->xso.dev->xfrmdev_ops->xdo_dev_offload_ok(skb, x);
430 
431 	return true;
432 }
433 EXPORT_SYMBOL_GPL(xfrm_dev_offload_ok);
434 
435 void xfrm_dev_resume(struct sk_buff *skb)
436 {
437 	struct net_device *dev = skb->dev;
438 	int ret = NETDEV_TX_BUSY;
439 	struct netdev_queue *txq;
440 	struct softnet_data *sd;
441 	unsigned long flags;
442 
443 	rcu_read_lock();
444 	txq = netdev_core_pick_tx(dev, skb, NULL);
445 
446 	HARD_TX_LOCK(dev, txq, smp_processor_id());
447 	if (!netif_xmit_frozen_or_stopped(txq))
448 		skb = dev_hard_start_xmit(skb, dev, txq, &ret);
449 	HARD_TX_UNLOCK(dev, txq);
450 
451 	if (!dev_xmit_complete(ret)) {
452 		local_irq_save(flags);
453 		sd = this_cpu_ptr(&softnet_data);
454 		skb_queue_tail(&sd->xfrm_backlog, skb);
455 		raise_softirq_irqoff(NET_TX_SOFTIRQ);
456 		local_irq_restore(flags);
457 	}
458 	rcu_read_unlock();
459 }
460 EXPORT_SYMBOL_GPL(xfrm_dev_resume);
461 
462 void xfrm_dev_backlog(struct softnet_data *sd)
463 {
464 	struct sk_buff_head *xfrm_backlog = &sd->xfrm_backlog;
465 	struct sk_buff_head list;
466 	struct sk_buff *skb;
467 
468 	if (skb_queue_empty(xfrm_backlog))
469 		return;
470 
471 	__skb_queue_head_init(&list);
472 
473 	spin_lock(&xfrm_backlog->lock);
474 	skb_queue_splice_init(xfrm_backlog, &list);
475 	spin_unlock(&xfrm_backlog->lock);
476 
477 	while (!skb_queue_empty(&list)) {
478 		skb = __skb_dequeue(&list);
479 		xfrm_dev_resume(skb);
480 	}
481 
482 }
483 #endif
484 
485 static int xfrm_api_check(struct net_device *dev)
486 {
487 #ifdef CONFIG_XFRM_OFFLOAD
488 	if ((dev->features & NETIF_F_HW_ESP_TX_CSUM) &&
489 	    !(dev->features & NETIF_F_HW_ESP))
490 		return NOTIFY_BAD;
491 
492 	if ((dev->features & NETIF_F_HW_ESP) &&
493 	    (!(dev->xfrmdev_ops &&
494 	       dev->xfrmdev_ops->xdo_dev_state_add &&
495 	       dev->xfrmdev_ops->xdo_dev_state_delete)))
496 		return NOTIFY_BAD;
497 #else
498 	if (dev->features & (NETIF_F_HW_ESP | NETIF_F_HW_ESP_TX_CSUM))
499 		return NOTIFY_BAD;
500 #endif
501 
502 	return NOTIFY_DONE;
503 }
504 
505 static int xfrm_dev_down(struct net_device *dev)
506 {
507 	if (dev->features & NETIF_F_HW_ESP) {
508 		xfrm_dev_state_flush(dev_net(dev), dev, true);
509 		xfrm_dev_policy_flush(dev_net(dev), dev, true);
510 	}
511 
512 	return NOTIFY_DONE;
513 }
514 
515 static int xfrm_dev_event(struct notifier_block *this, unsigned long event, void *ptr)
516 {
517 	struct net_device *dev = netdev_notifier_info_to_dev(ptr);
518 
519 	switch (event) {
520 	case NETDEV_REGISTER:
521 		return xfrm_api_check(dev);
522 
523 	case NETDEV_FEAT_CHANGE:
524 		return xfrm_api_check(dev);
525 
526 	case NETDEV_DOWN:
527 	case NETDEV_UNREGISTER:
528 		return xfrm_dev_down(dev);
529 	}
530 	return NOTIFY_DONE;
531 }
532 
533 static struct notifier_block xfrm_dev_notifier = {
534 	.notifier_call	= xfrm_dev_event,
535 };
536 
537 void __init xfrm_dev_init(void)
538 {
539 	register_netdevice_notifier(&xfrm_dev_notifier);
540 }
541