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 tcf_csum_init(struct net *n, struct nlattr *nla, struct nlattr *est,
46 struct tc_action *a, int ovr, int bind)
47 {
48 struct nlattr *tb[TCA_CSUM_MAX + 1];
49 struct tc_csum *parm;
50 struct tcf_csum *p;
51 int ret = 0, err;
52
53 if (nla == NULL)
54 return -EINVAL;
55
56 err = nla_parse_nested(tb, TCA_CSUM_MAX, nla, csum_policy);
57 if (err < 0)
58 return err;
59
60 if (tb[TCA_CSUM_PARMS] == NULL)
61 return -EINVAL;
62 parm = nla_data(tb[TCA_CSUM_PARMS]);
63
64 if (!tcf_hash_check(parm->index, a, bind)) {
65 ret = tcf_hash_create(parm->index, est, a, sizeof(*p),
66 bind, false);
67 if (ret)
68 return ret;
69 ret = ACT_P_CREATED;
70 } else {
71 if (bind)/* dont override defaults */
72 return 0;
73 tcf_hash_release(a, bind);
74 if (!ovr)
75 return -EEXIST;
76 }
77
78 p = to_tcf_csum(a);
79 spin_lock_bh(&p->tcf_lock);
80 p->tcf_action = parm->action;
81 p->update_flags = parm->update_flags;
82 spin_unlock_bh(&p->tcf_lock);
83
84 if (ret == ACT_P_CREATED)
85 tcf_hash_insert(a);
86
87 return ret;
88 }
89
90 /**
91 * tcf_csum_skb_nextlayer - Get next layer pointer
92 * @skb: sk_buff to use
93 * @ihl: previous summed headers length
94 * @ipl: complete packet length
95 * @jhl: next header length
96 *
97 * Check the expected next layer availability in the specified sk_buff.
98 * Return the next layer pointer if pass, NULL otherwise.
99 */
100 static void *tcf_csum_skb_nextlayer(struct sk_buff *skb,
101 unsigned int ihl, unsigned int ipl,
102 unsigned int jhl)
103 {
104 int ntkoff = skb_network_offset(skb);
105 int hl = ihl + jhl;
106
107 if (!pskb_may_pull(skb, ipl + ntkoff) || (ipl < hl) ||
108 skb_try_make_writable(skb, hl + ntkoff))
109 return NULL;
110 else
111 return (void *)(skb_network_header(skb) + ihl);
112 }
113
114 static int tcf_csum_ipv4_icmp(struct sk_buff *skb,
115 unsigned int ihl, unsigned int ipl)
116 {
117 struct icmphdr *icmph;
118
119 icmph = tcf_csum_skb_nextlayer(skb, ihl, ipl, sizeof(*icmph));
120 if (icmph == NULL)
121 return 0;
122
123 icmph->checksum = 0;
124 skb->csum = csum_partial(icmph, ipl - ihl, 0);
125 icmph->checksum = csum_fold(skb->csum);
126
127 skb->ip_summed = CHECKSUM_NONE;
128
129 return 1;
130 }
131
132 static int tcf_csum_ipv4_igmp(struct sk_buff *skb,
133 unsigned int ihl, unsigned int ipl)
134 {
135 struct igmphdr *igmph;
136
137 igmph = tcf_csum_skb_nextlayer(skb, ihl, ipl, sizeof(*igmph));
138 if (igmph == NULL)
139 return 0;
140
141 igmph->csum = 0;
142 skb->csum = csum_partial(igmph, ipl - ihl, 0);
143 igmph->csum = csum_fold(skb->csum);
144
145 skb->ip_summed = CHECKSUM_NONE;
146
147 return 1;
148 }
149
150 static int tcf_csum_ipv6_icmp(struct sk_buff *skb,
151 unsigned int ihl, unsigned int ipl)
152 {
153 struct icmp6hdr *icmp6h;
154 const struct ipv6hdr *ip6h;
155
156 icmp6h = tcf_csum_skb_nextlayer(skb, ihl, ipl, sizeof(*icmp6h));
157 if (icmp6h == NULL)
158 return 0;
159
160 ip6h = ipv6_hdr(skb);
161 icmp6h->icmp6_cksum = 0;
162 skb->csum = csum_partial(icmp6h, ipl - ihl, 0);
163 icmp6h->icmp6_cksum = csum_ipv6_magic(&ip6h->saddr, &ip6h->daddr,
164 ipl - ihl, IPPROTO_ICMPV6,
165 skb->csum);
166
167 skb->ip_summed = CHECKSUM_NONE;
168
169 return 1;
170 }
171
172 static int tcf_csum_ipv4_tcp(struct sk_buff *skb,
173 unsigned int ihl, unsigned int ipl)
174 {
175 struct tcphdr *tcph;
176 const struct iphdr *iph;
177
178 if (skb_is_gso(skb) && skb_shinfo(skb)->gso_type & SKB_GSO_TCPV4)
179 return 1;
180
181 tcph = tcf_csum_skb_nextlayer(skb, ihl, ipl, sizeof(*tcph));
182 if (tcph == NULL)
183 return 0;
184
185 iph = ip_hdr(skb);
186 tcph->check = 0;
187 skb->csum = csum_partial(tcph, ipl - ihl, 0);
188 tcph->check = tcp_v4_check(ipl - ihl,
189 iph->saddr, iph->daddr, skb->csum);
190
191 skb->ip_summed = CHECKSUM_NONE;
192
193 return 1;
194 }
195
196 static int tcf_csum_ipv6_tcp(struct sk_buff *skb,
197 unsigned int ihl, unsigned int ipl)
198 {
199 struct tcphdr *tcph;
200 const struct ipv6hdr *ip6h;
201
202 if (skb_is_gso(skb) && skb_shinfo(skb)->gso_type & SKB_GSO_TCPV6)
203 return 1;
204
205 tcph = tcf_csum_skb_nextlayer(skb, ihl, ipl, sizeof(*tcph));
206 if (tcph == NULL)
207 return 0;
208
209 ip6h = ipv6_hdr(skb);
210 tcph->check = 0;
211 skb->csum = csum_partial(tcph, ipl - ihl, 0);
212 tcph->check = csum_ipv6_magic(&ip6h->saddr, &ip6h->daddr,
213 ipl - ihl, IPPROTO_TCP,
214 skb->csum);
215
216 skb->ip_summed = CHECKSUM_NONE;
217
218 return 1;
219 }
220
221 static int tcf_csum_ipv4_udp(struct sk_buff *skb,
222 unsigned int ihl, unsigned int ipl, int udplite)
223 {
224 struct udphdr *udph;
225 const struct iphdr *iph;
226 u16 ul;
227
228 if (skb_is_gso(skb) && skb_shinfo(skb)->gso_type & SKB_GSO_UDP)
229 return 1;
230
231 /*
232 * Support both UDP and UDPLITE checksum algorithms, Don't use
233 * udph->len to get the real length without any protocol check,
234 * UDPLITE uses udph->len for another thing,
235 * Use iph->tot_len, or just ipl.
236 */
237
238 udph = tcf_csum_skb_nextlayer(skb, ihl, ipl, sizeof(*udph));
239 if (udph == NULL)
240 return 0;
241
242 iph = ip_hdr(skb);
243 ul = ntohs(udph->len);
244
245 if (udplite || udph->check) {
246
247 udph->check = 0;
248
249 if (udplite) {
250 if (ul == 0)
251 skb->csum = csum_partial(udph, ipl - ihl, 0);
252 else if ((ul >= sizeof(*udph)) && (ul <= ipl - ihl))
253 skb->csum = csum_partial(udph, ul, 0);
254 else
255 goto ignore_obscure_skb;
256 } else {
257 if (ul != ipl - ihl)
258 goto ignore_obscure_skb;
259
260 skb->csum = csum_partial(udph, ul, 0);
261 }
262
263 udph->check = csum_tcpudp_magic(iph->saddr, iph->daddr,
264 ul, iph->protocol,
265 skb->csum);
266
267 if (!udph->check)
268 udph->check = CSUM_MANGLED_0;
269 }
270
271 skb->ip_summed = CHECKSUM_NONE;
272
273 ignore_obscure_skb:
274 return 1;
275 }
276
277 static int tcf_csum_ipv6_udp(struct sk_buff *skb,
278 unsigned int ihl, unsigned int ipl, int udplite)
279 {
280 struct udphdr *udph;
281 const struct ipv6hdr *ip6h;
282 u16 ul;
283
284 if (skb_is_gso(skb) && skb_shinfo(skb)->gso_type & SKB_GSO_UDP)
285 return 1;
286
287 /*
288 * Support both UDP and UDPLITE checksum algorithms, Don't use
289 * udph->len to get the real length without any protocol check,
290 * UDPLITE uses udph->len for another thing,
291 * Use ip6h->payload_len + sizeof(*ip6h) ... , or just ipl.
292 */
293
294 udph = tcf_csum_skb_nextlayer(skb, ihl, ipl, sizeof(*udph));
295 if (udph == NULL)
296 return 0;
297
298 ip6h = ipv6_hdr(skb);
299 ul = ntohs(udph->len);
300
301 udph->check = 0;
302
303 if (udplite) {
304 if (ul == 0)
305 skb->csum = csum_partial(udph, ipl - ihl, 0);
306
307 else if ((ul >= sizeof(*udph)) && (ul <= ipl - ihl))
308 skb->csum = csum_partial(udph, ul, 0);
309
310 else
311 goto ignore_obscure_skb;
312 } else {
313 if (ul != ipl - ihl)
314 goto ignore_obscure_skb;
315
316 skb->csum = csum_partial(udph, ul, 0);
317 }
318
319 udph->check = csum_ipv6_magic(&ip6h->saddr, &ip6h->daddr, ul,
320 udplite ? IPPROTO_UDPLITE : IPPROTO_UDP,
321 skb->csum);
322
323 if (!udph->check)
324 udph->check = CSUM_MANGLED_0;
325
326 skb->ip_summed = CHECKSUM_NONE;
327
328 ignore_obscure_skb:
329 return 1;
330 }
331
332 static int tcf_csum_ipv4(struct sk_buff *skb, u32 update_flags)
333 {
334 const struct iphdr *iph;
335 int ntkoff;
336
337 ntkoff = skb_network_offset(skb);
338
339 if (!pskb_may_pull(skb, sizeof(*iph) + ntkoff))
340 goto fail;
341
342 iph = ip_hdr(skb);
343
344 switch (iph->frag_off & htons(IP_OFFSET) ? 0 : iph->protocol) {
345 case IPPROTO_ICMP:
346 if (update_flags & TCA_CSUM_UPDATE_FLAG_ICMP)
347 if (!tcf_csum_ipv4_icmp(skb, iph->ihl * 4,
348 ntohs(iph->tot_len)))
349 goto fail;
350 break;
351 case IPPROTO_IGMP:
352 if (update_flags & TCA_CSUM_UPDATE_FLAG_IGMP)
353 if (!tcf_csum_ipv4_igmp(skb, iph->ihl * 4,
354 ntohs(iph->tot_len)))
355 goto fail;
356 break;
357 case IPPROTO_TCP:
358 if (update_flags & TCA_CSUM_UPDATE_FLAG_TCP)
359 if (!tcf_csum_ipv4_tcp(skb, iph->ihl * 4,
360 ntohs(iph->tot_len)))
361 goto fail;
362 break;
363 case IPPROTO_UDP:
364 if (update_flags & TCA_CSUM_UPDATE_FLAG_UDP)
365 if (!tcf_csum_ipv4_udp(skb, iph->ihl * 4,
366 ntohs(iph->tot_len), 0))
367 goto fail;
368 break;
369 case IPPROTO_UDPLITE:
370 if (update_flags & TCA_CSUM_UPDATE_FLAG_UDPLITE)
371 if (!tcf_csum_ipv4_udp(skb, iph->ihl * 4,
372 ntohs(iph->tot_len), 1))
373 goto fail;
374 break;
375 }
376
377 if (update_flags & TCA_CSUM_UPDATE_FLAG_IPV4HDR) {
378 if (skb_try_make_writable(skb, sizeof(*iph) + ntkoff))
379 goto fail;
380
381 ip_send_check(ip_hdr(skb));
382 }
383
384 return 1;
385
386 fail:
387 return 0;
388 }
389
390 static int tcf_csum_ipv6_hopopts(struct ipv6_opt_hdr *ip6xh,
391 unsigned int ixhl, unsigned int *pl)
392 {
393 int off, len, optlen;
394 unsigned char *xh = (void *)ip6xh;
395
396 off = sizeof(*ip6xh);
397 len = ixhl - off;
398
399 while (len > 1) {
400 switch (xh[off]) {
401 case IPV6_TLV_PAD1:
402 optlen = 1;
403 break;
404 case IPV6_TLV_JUMBO:
405 optlen = xh[off + 1] + 2;
406 if (optlen != 6 || len < 6 || (off & 3) != 2)
407 /* wrong jumbo option length/alignment */
408 return 0;
409 *pl = ntohl(*(__be32 *)(xh + off + 2));
410 goto done;
411 default:
412 optlen = xh[off + 1] + 2;
413 if (optlen > len)
414 /* ignore obscure options */
415 goto done;
416 break;
417 }
418 off += optlen;
419 len -= optlen;
420 }
421
422 done:
423 return 1;
424 }
425
426 static int tcf_csum_ipv6(struct sk_buff *skb, u32 update_flags)
427 {
428 struct ipv6hdr *ip6h;
429 struct ipv6_opt_hdr *ip6xh;
430 unsigned int hl, ixhl;
431 unsigned int pl;
432 int ntkoff;
433 u8 nexthdr;
434
435 ntkoff = skb_network_offset(skb);
436
437 hl = sizeof(*ip6h);
438
439 if (!pskb_may_pull(skb, hl + ntkoff))
440 goto fail;
441
442 ip6h = ipv6_hdr(skb);
443
444 pl = ntohs(ip6h->payload_len);
445 nexthdr = ip6h->nexthdr;
446
447 do {
448 switch (nexthdr) {
449 case NEXTHDR_FRAGMENT:
450 goto ignore_skb;
451 case NEXTHDR_ROUTING:
452 case NEXTHDR_HOP:
453 case NEXTHDR_DEST:
454 if (!pskb_may_pull(skb, hl + sizeof(*ip6xh) + ntkoff))
455 goto fail;
456 ip6xh = (void *)(skb_network_header(skb) + hl);
457 ixhl = ipv6_optlen(ip6xh);
458 if (!pskb_may_pull(skb, hl + ixhl + ntkoff))
459 goto fail;
460 ip6xh = (void *)(skb_network_header(skb) + hl);
461 if ((nexthdr == NEXTHDR_HOP) &&
462 !(tcf_csum_ipv6_hopopts(ip6xh, ixhl, &pl)))
463 goto fail;
464 nexthdr = ip6xh->nexthdr;
465 hl += ixhl;
466 break;
467 case IPPROTO_ICMPV6:
468 if (update_flags & TCA_CSUM_UPDATE_FLAG_ICMP)
469 if (!tcf_csum_ipv6_icmp(skb,
470 hl, pl + sizeof(*ip6h)))
471 goto fail;
472 goto done;
473 case IPPROTO_TCP:
474 if (update_flags & TCA_CSUM_UPDATE_FLAG_TCP)
475 if (!tcf_csum_ipv6_tcp(skb,
476 hl, pl + sizeof(*ip6h)))
477 goto fail;
478 goto done;
479 case IPPROTO_UDP:
480 if (update_flags & TCA_CSUM_UPDATE_FLAG_UDP)
481 if (!tcf_csum_ipv6_udp(skb, hl,
482 pl + sizeof(*ip6h), 0))
483 goto fail;
484 goto done;
485 case IPPROTO_UDPLITE:
486 if (update_flags & TCA_CSUM_UPDATE_FLAG_UDPLITE)
487 if (!tcf_csum_ipv6_udp(skb, hl,
488 pl + sizeof(*ip6h), 1))
489 goto fail;
490 goto done;
491 default:
492 goto ignore_skb;
493 }
494 } while (pskb_may_pull(skb, hl + 1 + ntkoff));
495
496 done:
497 ignore_skb:
498 return 1;
499
500 fail:
501 return 0;
502 }
503
504 static int tcf_csum(struct sk_buff *skb,
505 const struct tc_action *a, struct tcf_result *res)
506 {
507 struct tcf_csum *p = a->priv;
508 int action;
509 u32 update_flags;
510
511 spin_lock(&p->tcf_lock);
512 p->tcf_tm.lastuse = jiffies;
513 bstats_update(&p->tcf_bstats, skb);
514 action = p->tcf_action;
515 update_flags = p->update_flags;
516 spin_unlock(&p->tcf_lock);
517
518 if (unlikely(action == TC_ACT_SHOT))
519 goto drop;
520
521 switch (tc_skb_protocol(skb)) {
522 case cpu_to_be16(ETH_P_IP):
523 if (!tcf_csum_ipv4(skb, update_flags))
524 goto drop;
525 break;
526 case cpu_to_be16(ETH_P_IPV6):
527 if (!tcf_csum_ipv6(skb, update_flags))
528 goto drop;
529 break;
530 }
531
532 return action;
533
534 drop:
535 spin_lock(&p->tcf_lock);
536 p->tcf_qstats.drops++;
537 spin_unlock(&p->tcf_lock);
538 return TC_ACT_SHOT;
539 }
540
541 static int tcf_csum_dump(struct sk_buff *skb,
542 struct tc_action *a, int bind, int ref)
543 {
544 unsigned char *b = skb_tail_pointer(skb);
545 struct tcf_csum *p = a->priv;
546 struct tc_csum opt = {
547 .update_flags = p->update_flags,
548 .index = p->tcf_index,
549 .action = p->tcf_action,
550 .refcnt = p->tcf_refcnt - ref,
551 .bindcnt = p->tcf_bindcnt - bind,
552 };
553 struct tcf_t t;
554
555 if (nla_put(skb, TCA_CSUM_PARMS, sizeof(opt), &opt))
556 goto nla_put_failure;
557 t.install = jiffies_to_clock_t(jiffies - p->tcf_tm.install);
558 t.lastuse = jiffies_to_clock_t(jiffies - p->tcf_tm.lastuse);
559 t.expires = jiffies_to_clock_t(p->tcf_tm.expires);
560 if (nla_put(skb, TCA_CSUM_TM, sizeof(t), &t))
561 goto nla_put_failure;
562
563 return skb->len;
564
565 nla_put_failure:
566 nlmsg_trim(skb, b);
567 return -1;
568 }
569
570 static struct tc_action_ops act_csum_ops = {
571 .kind = "csum",
572 .type = TCA_ACT_CSUM,
573 .owner = THIS_MODULE,
574 .act = tcf_csum,
575 .dump = tcf_csum_dump,
576 .init = tcf_csum_init,
577 };
578
579 MODULE_DESCRIPTION("Checksum updating actions");
580 MODULE_LICENSE("GPL");
581
582 static int __init csum_init_module(void)
583 {
584 return tcf_register_action(&act_csum_ops, CSUM_TAB_MASK);
585 }
586
587 static void __exit csum_cleanup_module(void)
588 {
589 tcf_unregister_action(&act_csum_ops);
590 }
591
592 module_init(csum_init_module);
593 module_exit(csum_cleanup_module);
594
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