xref: /openbmc/linux/net/sched/act_csum.c (revision 23c2b932) 
1 /*
2  * Checksum updating actions
3  *
4  * Copyright (c) 2010 Gregoire Baron <baronchon@n7mm.org>
5  *
6  * This program is free software; you can redistribute it and/or modify it
7  * under the terms of the GNU General Public License as published by the Free
8  * Software Foundation; either version 2 of the License, or (at your option)
9  * any later version.
10  *
11  */
12 
13 #include <linux/types.h>
14 #include <linux/init.h>
15 #include <linux/kernel.h>
16 #include <linux/module.h>
17 #include <linux/spinlock.h>
18 
19 #include <linux/netlink.h>
20 #include <net/netlink.h>
21 #include <linux/rtnetlink.h>
22 
23 #include <linux/skbuff.h>
24 
25 #include <net/ip.h>
26 #include <net/ipv6.h>
27 #include <net/icmp.h>
28 #include <linux/icmpv6.h>
29 #include <linux/igmp.h>
30 #include <net/tcp.h>
31 #include <net/udp.h>
32 #include <net/ip6_checksum.h>
33 
34 #include <net/act_api.h>
35 
36 #include <linux/tc_act/tc_csum.h>
37 #include <net/tc_act/tc_csum.h>
38 
39 #define CSUM_TAB_MASK 15
40 
41 static const struct nla_policy csum_policy[TCA_CSUM_MAX + 1] = {
42 	[TCA_CSUM_PARMS] = { .len = sizeof(struct tc_csum), },
43 };
44 
45 static int csum_net_id;
46 
47 static int tcf_csum_init(struct net *net, struct nlattr *nla,
48 			 struct nlattr *est, struct tc_action *a, int ovr,
49 			 int bind)
50 {
51 	struct tc_action_net *tn = net_generic(net, csum_net_id);
52 	struct nlattr *tb[TCA_CSUM_MAX + 1];
53 	struct tc_csum *parm;
54 	struct tcf_csum *p;
55 	int ret = 0, err;
56 
57 	if (nla == NULL)
58 		return -EINVAL;
59 
60 	err = nla_parse_nested(tb, TCA_CSUM_MAX, nla, csum_policy);
61 	if (err < 0)
62 		return err;
63 
64 	if (tb[TCA_CSUM_PARMS] == NULL)
65 		return -EINVAL;
66 	parm = nla_data(tb[TCA_CSUM_PARMS]);
67 
68 	if (!tcf_hash_check(tn, parm->index, a, bind)) {
69 		ret = tcf_hash_create(tn, parm->index, est, a,
70 				      sizeof(*p), bind, false);
71 		if (ret)
72 			return ret;
73 		ret = ACT_P_CREATED;
74 	} else {
75 		if (bind)/* dont override defaults */
76 			return 0;
77 		tcf_hash_release(a, bind);
78 		if (!ovr)
79 			return -EEXIST;
80 	}
81 
82 	p = to_tcf_csum(a);
83 	spin_lock_bh(&p->tcf_lock);
84 	p->tcf_action = parm->action;
85 	p->update_flags = parm->update_flags;
86 	spin_unlock_bh(&p->tcf_lock);
87 
88 	if (ret == ACT_P_CREATED)
89 		tcf_hash_insert(tn, a);
90 
91 	return ret;
92 }
93 
94 /**
95  * tcf_csum_skb_nextlayer - Get next layer pointer
96  * @skb: sk_buff to use
97  * @ihl: previous summed headers length
98  * @ipl: complete packet length
99  * @jhl: next header length
100  *
101  * Check the expected next layer availability in the specified sk_buff.
102  * Return the next layer pointer if pass, NULL otherwise.
103  */
104 static void *tcf_csum_skb_nextlayer(struct sk_buff *skb,
105 				    unsigned int ihl, unsigned int ipl,
106 				    unsigned int jhl)
107 {
108 	int ntkoff = skb_network_offset(skb);
109 	int hl = ihl + jhl;
110 
111 	if (!pskb_may_pull(skb, ipl + ntkoff) || (ipl < hl) ||
112 	    skb_try_make_writable(skb, hl + ntkoff))
113 		return NULL;
114 	else
115 		return (void *)(skb_network_header(skb) + ihl);
116 }
117 
118 static int tcf_csum_ipv4_icmp(struct sk_buff *skb,
119 			      unsigned int ihl, unsigned int ipl)
120 {
121 	struct icmphdr *icmph;
122 
123 	icmph = tcf_csum_skb_nextlayer(skb, ihl, ipl, sizeof(*icmph));
124 	if (icmph == NULL)
125 		return 0;
126 
127 	icmph->checksum = 0;
128 	skb->csum = csum_partial(icmph, ipl - ihl, 0);
129 	icmph->checksum = csum_fold(skb->csum);
130 
131 	skb->ip_summed = CHECKSUM_NONE;
132 
133 	return 1;
134 }
135 
136 static int tcf_csum_ipv4_igmp(struct sk_buff *skb,
137 			      unsigned int ihl, unsigned int ipl)
138 {
139 	struct igmphdr *igmph;
140 
141 	igmph = tcf_csum_skb_nextlayer(skb, ihl, ipl, sizeof(*igmph));
142 	if (igmph == NULL)
143 		return 0;
144 
145 	igmph->csum = 0;
146 	skb->csum = csum_partial(igmph, ipl - ihl, 0);
147 	igmph->csum = csum_fold(skb->csum);
148 
149 	skb->ip_summed = CHECKSUM_NONE;
150 
151 	return 1;
152 }
153 
154 static int tcf_csum_ipv6_icmp(struct sk_buff *skb,
155 			      unsigned int ihl, unsigned int ipl)
156 {
157 	struct icmp6hdr *icmp6h;
158 	const struct ipv6hdr *ip6h;
159 
160 	icmp6h = tcf_csum_skb_nextlayer(skb, ihl, ipl, sizeof(*icmp6h));
161 	if (icmp6h == NULL)
162 		return 0;
163 
164 	ip6h = ipv6_hdr(skb);
165 	icmp6h->icmp6_cksum = 0;
166 	skb->csum = csum_partial(icmp6h, ipl - ihl, 0);
167 	icmp6h->icmp6_cksum = csum_ipv6_magic(&ip6h->saddr, &ip6h->daddr,
168 					      ipl - ihl, IPPROTO_ICMPV6,
169 					      skb->csum);
170 
171 	skb->ip_summed = CHECKSUM_NONE;
172 
173 	return 1;
174 }
175 
176 static int tcf_csum_ipv4_tcp(struct sk_buff *skb,
177 			     unsigned int ihl, unsigned int ipl)
178 {
179 	struct tcphdr *tcph;
180 	const struct iphdr *iph;
181 
182 	tcph = tcf_csum_skb_nextlayer(skb, ihl, ipl, sizeof(*tcph));
183 	if (tcph == NULL)
184 		return 0;
185 
186 	iph = ip_hdr(skb);
187 	tcph->check = 0;
188 	skb->csum = csum_partial(tcph, ipl - ihl, 0);
189 	tcph->check = tcp_v4_check(ipl - ihl,
190 				   iph->saddr, iph->daddr, skb->csum);
191 
192 	skb->ip_summed = CHECKSUM_NONE;
193 
194 	return 1;
195 }
196 
197 static int tcf_csum_ipv6_tcp(struct sk_buff *skb,
198 			     unsigned int ihl, unsigned int ipl)
199 {
200 	struct tcphdr *tcph;
201 	const struct ipv6hdr *ip6h;
202 
203 	tcph = tcf_csum_skb_nextlayer(skb, ihl, ipl, sizeof(*tcph));
204 	if (tcph == NULL)
205 		return 0;
206 
207 	ip6h = ipv6_hdr(skb);
208 	tcph->check = 0;
209 	skb->csum = csum_partial(tcph, ipl - ihl, 0);
210 	tcph->check = csum_ipv6_magic(&ip6h->saddr, &ip6h->daddr,
211 				      ipl - ihl, IPPROTO_TCP,
212 				      skb->csum);
213 
214 	skb->ip_summed = CHECKSUM_NONE;
215 
216 	return 1;
217 }
218 
219 static int tcf_csum_ipv4_udp(struct sk_buff *skb,
220 			     unsigned int ihl, unsigned int ipl, int udplite)
221 {
222 	struct udphdr *udph;
223 	const struct iphdr *iph;
224 	u16 ul;
225 
226 	/*
227 	 * Support both UDP and UDPLITE checksum algorithms, Don't use
228 	 * udph->len to get the real length without any protocol check,
229 	 * UDPLITE uses udph->len for another thing,
230 	 * Use iph->tot_len, or just ipl.
231 	 */
232 
233 	udph = tcf_csum_skb_nextlayer(skb, ihl, ipl, sizeof(*udph));
234 	if (udph == NULL)
235 		return 0;
236 
237 	iph = ip_hdr(skb);
238 	ul = ntohs(udph->len);
239 
240 	if (udplite || udph->check) {
241 
242 		udph->check = 0;
243 
244 		if (udplite) {
245 			if (ul == 0)
246 				skb->csum = csum_partial(udph, ipl - ihl, 0);
247 			else if ((ul >= sizeof(*udph)) && (ul <= ipl - ihl))
248 				skb->csum = csum_partial(udph, ul, 0);
249 			else
250 				goto ignore_obscure_skb;
251 		} else {
252 			if (ul != ipl - ihl)
253 				goto ignore_obscure_skb;
254 
255 			skb->csum = csum_partial(udph, ul, 0);
256 		}
257 
258 		udph->check = csum_tcpudp_magic(iph->saddr, iph->daddr,
259 						ul, iph->protocol,
260 						skb->csum);
261 
262 		if (!udph->check)
263 			udph->check = CSUM_MANGLED_0;
264 	}
265 
266 	skb->ip_summed = CHECKSUM_NONE;
267 
268 ignore_obscure_skb:
269 	return 1;
270 }
271 
272 static int tcf_csum_ipv6_udp(struct sk_buff *skb,
273 			     unsigned int ihl, unsigned int ipl, int udplite)
274 {
275 	struct udphdr *udph;
276 	const struct ipv6hdr *ip6h;
277 	u16 ul;
278 
279 	/*
280 	 * Support both UDP and UDPLITE checksum algorithms, Don't use
281 	 * udph->len to get the real length without any protocol check,
282 	 * UDPLITE uses udph->len for another thing,
283 	 * Use ip6h->payload_len + sizeof(*ip6h) ... , or just ipl.
284 	 */
285 
286 	udph = tcf_csum_skb_nextlayer(skb, ihl, ipl, sizeof(*udph));
287 	if (udph == NULL)
288 		return 0;
289 
290 	ip6h = ipv6_hdr(skb);
291 	ul = ntohs(udph->len);
292 
293 	udph->check = 0;
294 
295 	if (udplite) {
296 		if (ul == 0)
297 			skb->csum = csum_partial(udph, ipl - ihl, 0);
298 
299 		else if ((ul >= sizeof(*udph)) && (ul <= ipl - ihl))
300 			skb->csum = csum_partial(udph, ul, 0);
301 
302 		else
303 			goto ignore_obscure_skb;
304 	} else {
305 		if (ul != ipl - ihl)
306 			goto ignore_obscure_skb;
307 
308 		skb->csum = csum_partial(udph, ul, 0);
309 	}
310 
311 	udph->check = csum_ipv6_magic(&ip6h->saddr, &ip6h->daddr, ul,
312 				      udplite ? IPPROTO_UDPLITE : IPPROTO_UDP,
313 				      skb->csum);
314 
315 	if (!udph->check)
316 		udph->check = CSUM_MANGLED_0;
317 
318 	skb->ip_summed = CHECKSUM_NONE;
319 
320 ignore_obscure_skb:
321 	return 1;
322 }
323 
324 static int tcf_csum_ipv4(struct sk_buff *skb, u32 update_flags)
325 {
326 	const struct iphdr *iph;
327 	int ntkoff;
328 
329 	ntkoff = skb_network_offset(skb);
330 
331 	if (!pskb_may_pull(skb, sizeof(*iph) + ntkoff))
332 		goto fail;
333 
334 	iph = ip_hdr(skb);
335 
336 	switch (iph->frag_off & htons(IP_OFFSET) ? 0 : iph->protocol) {
337 	case IPPROTO_ICMP:
338 		if (update_flags & TCA_CSUM_UPDATE_FLAG_ICMP)
339 			if (!tcf_csum_ipv4_icmp(skb, iph->ihl * 4,
340 						ntohs(iph->tot_len)))
341 				goto fail;
342 		break;
343 	case IPPROTO_IGMP:
344 		if (update_flags & TCA_CSUM_UPDATE_FLAG_IGMP)
345 			if (!tcf_csum_ipv4_igmp(skb, iph->ihl * 4,
346 						ntohs(iph->tot_len)))
347 				goto fail;
348 		break;
349 	case IPPROTO_TCP:
350 		if (update_flags & TCA_CSUM_UPDATE_FLAG_TCP)
351 			if (!tcf_csum_ipv4_tcp(skb, iph->ihl * 4,
352 					       ntohs(iph->tot_len)))
353 				goto fail;
354 		break;
355 	case IPPROTO_UDP:
356 		if (update_flags & TCA_CSUM_UPDATE_FLAG_UDP)
357 			if (!tcf_csum_ipv4_udp(skb, iph->ihl * 4,
358 					       ntohs(iph->tot_len), 0))
359 				goto fail;
360 		break;
361 	case IPPROTO_UDPLITE:
362 		if (update_flags & TCA_CSUM_UPDATE_FLAG_UDPLITE)
363 			if (!tcf_csum_ipv4_udp(skb, iph->ihl * 4,
364 					       ntohs(iph->tot_len), 1))
365 				goto fail;
366 		break;
367 	}
368 
369 	if (update_flags & TCA_CSUM_UPDATE_FLAG_IPV4HDR) {
370 		if (skb_try_make_writable(skb, sizeof(*iph) + ntkoff))
371 			goto fail;
372 
373 		ip_send_check(ip_hdr(skb));
374 	}
375 
376 	return 1;
377 
378 fail:
379 	return 0;
380 }
381 
382 static int tcf_csum_ipv6_hopopts(struct ipv6_opt_hdr *ip6xh,
383 				 unsigned int ixhl, unsigned int *pl)
384 {
385 	int off, len, optlen;
386 	unsigned char *xh = (void *)ip6xh;
387 
388 	off = sizeof(*ip6xh);
389 	len = ixhl - off;
390 
391 	while (len > 1) {
392 		switch (xh[off]) {
393 		case IPV6_TLV_PAD1:
394 			optlen = 1;
395 			break;
396 		case IPV6_TLV_JUMBO:
397 			optlen = xh[off + 1] + 2;
398 			if (optlen != 6 || len < 6 || (off & 3) != 2)
399 				/* wrong jumbo option length/alignment */
400 				return 0;
401 			*pl = ntohl(*(__be32 *)(xh + off + 2));
402 			goto done;
403 		default:
404 			optlen = xh[off + 1] + 2;
405 			if (optlen > len)
406 				/* ignore obscure options */
407 				goto done;
408 			break;
409 		}
410 		off += optlen;
411 		len -= optlen;
412 	}
413 
414 done:
415 	return 1;
416 }
417 
418 static int tcf_csum_ipv6(struct sk_buff *skb, u32 update_flags)
419 {
420 	struct ipv6hdr *ip6h;
421 	struct ipv6_opt_hdr *ip6xh;
422 	unsigned int hl, ixhl;
423 	unsigned int pl;
424 	int ntkoff;
425 	u8 nexthdr;
426 
427 	ntkoff = skb_network_offset(skb);
428 
429 	hl = sizeof(*ip6h);
430 
431 	if (!pskb_may_pull(skb, hl + ntkoff))
432 		goto fail;
433 
434 	ip6h = ipv6_hdr(skb);
435 
436 	pl = ntohs(ip6h->payload_len);
437 	nexthdr = ip6h->nexthdr;
438 
439 	do {
440 		switch (nexthdr) {
441 		case NEXTHDR_FRAGMENT:
442 			goto ignore_skb;
443 		case NEXTHDR_ROUTING:
444 		case NEXTHDR_HOP:
445 		case NEXTHDR_DEST:
446 			if (!pskb_may_pull(skb, hl + sizeof(*ip6xh) + ntkoff))
447 				goto fail;
448 			ip6xh = (void *)(skb_network_header(skb) + hl);
449 			ixhl = ipv6_optlen(ip6xh);
450 			if (!pskb_may_pull(skb, hl + ixhl + ntkoff))
451 				goto fail;
452 			ip6xh = (void *)(skb_network_header(skb) + hl);
453 			if ((nexthdr == NEXTHDR_HOP) &&
454 			    !(tcf_csum_ipv6_hopopts(ip6xh, ixhl, &pl)))
455 				goto fail;
456 			nexthdr = ip6xh->nexthdr;
457 			hl += ixhl;
458 			break;
459 		case IPPROTO_ICMPV6:
460 			if (update_flags & TCA_CSUM_UPDATE_FLAG_ICMP)
461 				if (!tcf_csum_ipv6_icmp(skb,
462 							hl, pl + sizeof(*ip6h)))
463 					goto fail;
464 			goto done;
465 		case IPPROTO_TCP:
466 			if (update_flags & TCA_CSUM_UPDATE_FLAG_TCP)
467 				if (!tcf_csum_ipv6_tcp(skb,
468 						       hl, pl + sizeof(*ip6h)))
469 					goto fail;
470 			goto done;
471 		case IPPROTO_UDP:
472 			if (update_flags & TCA_CSUM_UPDATE_FLAG_UDP)
473 				if (!tcf_csum_ipv6_udp(skb, hl,
474 						       pl + sizeof(*ip6h), 0))
475 					goto fail;
476 			goto done;
477 		case IPPROTO_UDPLITE:
478 			if (update_flags & TCA_CSUM_UPDATE_FLAG_UDPLITE)
479 				if (!tcf_csum_ipv6_udp(skb, hl,
480 						       pl + sizeof(*ip6h), 1))
481 					goto fail;
482 			goto done;
483 		default:
484 			goto ignore_skb;
485 		}
486 	} while (pskb_may_pull(skb, hl + 1 + ntkoff));
487 
488 done:
489 ignore_skb:
490 	return 1;
491 
492 fail:
493 	return 0;
494 }
495 
496 static int tcf_csum(struct sk_buff *skb,
497 		    const struct tc_action *a, struct tcf_result *res)
498 {
499 	struct tcf_csum *p = a->priv;
500 	int action;
501 	u32 update_flags;
502 
503 	spin_lock(&p->tcf_lock);
504 	p->tcf_tm.lastuse = jiffies;
505 	bstats_update(&p->tcf_bstats, skb);
506 	action = p->tcf_action;
507 	update_flags = p->update_flags;
508 	spin_unlock(&p->tcf_lock);
509 
510 	if (unlikely(action == TC_ACT_SHOT))
511 		goto drop;
512 
513 	switch (tc_skb_protocol(skb)) {
514 	case cpu_to_be16(ETH_P_IP):
515 		if (!tcf_csum_ipv4(skb, update_flags))
516 			goto drop;
517 		break;
518 	case cpu_to_be16(ETH_P_IPV6):
519 		if (!tcf_csum_ipv6(skb, update_flags))
520 			goto drop;
521 		break;
522 	}
523 
524 	return action;
525 
526 drop:
527 	spin_lock(&p->tcf_lock);
528 	p->tcf_qstats.drops++;
529 	spin_unlock(&p->tcf_lock);
530 	return TC_ACT_SHOT;
531 }
532 
533 static int tcf_csum_dump(struct sk_buff *skb,
534 			 struct tc_action *a, int bind, int ref)
535 {
536 	unsigned char *b = skb_tail_pointer(skb);
537 	struct tcf_csum *p = a->priv;
538 	struct tc_csum opt = {
539 		.update_flags = p->update_flags,
540 		.index   = p->tcf_index,
541 		.action  = p->tcf_action,
542 		.refcnt  = p->tcf_refcnt - ref,
543 		.bindcnt = p->tcf_bindcnt - bind,
544 	};
545 	struct tcf_t t;
546 
547 	if (nla_put(skb, TCA_CSUM_PARMS, sizeof(opt), &opt))
548 		goto nla_put_failure;
549 	t.install = jiffies_to_clock_t(jiffies - p->tcf_tm.install);
550 	t.lastuse = jiffies_to_clock_t(jiffies - p->tcf_tm.lastuse);
551 	t.expires = jiffies_to_clock_t(p->tcf_tm.expires);
552 	if (nla_put_64bit(skb, TCA_CSUM_TM, sizeof(t), &t, TCA_CSUM_PAD))
553 		goto nla_put_failure;
554 
555 	return skb->len;
556 
557 nla_put_failure:
558 	nlmsg_trim(skb, b);
559 	return -1;
560 }
561 
562 static int tcf_csum_walker(struct net *net, struct sk_buff *skb,
563 			   struct netlink_callback *cb, int type,
564 			   struct tc_action *a)
565 {
566 	struct tc_action_net *tn = net_generic(net, csum_net_id);
567 
568 	return tcf_generic_walker(tn, skb, cb, type, a);
569 }
570 
571 static int tcf_csum_search(struct net *net, struct tc_action *a, u32 index)
572 {
573 	struct tc_action_net *tn = net_generic(net, csum_net_id);
574 
575 	return tcf_hash_search(tn, a, index);
576 }
577 
578 static struct tc_action_ops act_csum_ops = {
579 	.kind		= "csum",
580 	.type		= TCA_ACT_CSUM,
581 	.owner		= THIS_MODULE,
582 	.act		= tcf_csum,
583 	.dump		= tcf_csum_dump,
584 	.init		= tcf_csum_init,
585 	.walk		= tcf_csum_walker,
586 	.lookup		= tcf_csum_search,
587 };
588 
589 static __net_init int csum_init_net(struct net *net)
590 {
591 	struct tc_action_net *tn = net_generic(net, csum_net_id);
592 
593 	return tc_action_net_init(tn, &act_csum_ops, CSUM_TAB_MASK);
594 }
595 
596 static void __net_exit csum_exit_net(struct net *net)
597 {
598 	struct tc_action_net *tn = net_generic(net, csum_net_id);
599 
600 	tc_action_net_exit(tn);
601 }
602 
603 static struct pernet_operations csum_net_ops = {
604 	.init = csum_init_net,
605 	.exit = csum_exit_net,
606 	.id   = &csum_net_id,
607 	.size = sizeof(struct tc_action_net),
608 };
609 
610 MODULE_DESCRIPTION("Checksum updating actions");
611 MODULE_LICENSE("GPL");
612 
613 static int __init csum_init_module(void)
614 {
615 	return tcf_register_action(&act_csum_ops, &csum_net_ops);
616 }
617 
618 static void __exit csum_cleanup_module(void)
619 {
620 	tcf_unregister_action(&act_csum_ops, &csum_net_ops);
621 }
622 
623 module_init(csum_init_module);
624 module_exit(csum_cleanup_module);
625