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bf355b8d DL |
1 | /* |
2 | * SR-IPv6 implementation -- HMAC functions | |
3 | * | |
4 | * Author: | |
5 | * David Lebrun <david.lebrun@uclouvain.be> | |
6 | * | |
7 | * | |
8 | * This program is free software; you can redistribute it and/or | |
9 | * modify it under the terms of the GNU General Public License | |
10 | * as published by the Free Software Foundation; either version | |
11 | * 2 of the License, or (at your option) any later version. | |
12 | */ | |
13 | ||
14 | #include <linux/errno.h> | |
15 | #include <linux/types.h> | |
16 | #include <linux/socket.h> | |
17 | #include <linux/sockios.h> | |
18 | #include <linux/net.h> | |
19 | #include <linux/netdevice.h> | |
20 | #include <linux/in6.h> | |
21 | #include <linux/icmpv6.h> | |
22 | #include <linux/mroute6.h> | |
23 | #include <linux/slab.h> | |
24 | ||
25 | #include <linux/netfilter.h> | |
26 | #include <linux/netfilter_ipv6.h> | |
27 | ||
28 | #include <net/sock.h> | |
29 | #include <net/snmp.h> | |
30 | ||
31 | #include <net/ipv6.h> | |
32 | #include <net/protocol.h> | |
33 | #include <net/transp_v6.h> | |
34 | #include <net/rawv6.h> | |
35 | #include <net/ndisc.h> | |
36 | #include <net/ip6_route.h> | |
37 | #include <net/addrconf.h> | |
38 | #include <net/xfrm.h> | |
39 | ||
40 | #include <linux/cryptohash.h> | |
41 | #include <crypto/hash.h> | |
42 | #include <crypto/sha.h> | |
43 | #include <net/seg6.h> | |
44 | #include <net/genetlink.h> | |
45 | #include <net/seg6_hmac.h> | |
46 | #include <linux/random.h> | |
47 | ||
48 | static char * __percpu *hmac_ring; | |
49 | ||
50 | static int seg6_hmac_cmpfn(struct rhashtable_compare_arg *arg, const void *obj) | |
51 | { | |
52 | const struct seg6_hmac_info *hinfo = obj; | |
53 | ||
54 | return (hinfo->hmackeyid != *(__u32 *)arg->key); | |
55 | } | |
56 | ||
57 | static inline void seg6_hinfo_release(struct seg6_hmac_info *hinfo) | |
58 | { | |
59 | kfree_rcu(hinfo, rcu); | |
60 | } | |
61 | ||
62 | static void seg6_free_hi(void *ptr, void *arg) | |
63 | { | |
64 | struct seg6_hmac_info *hinfo = (struct seg6_hmac_info *)ptr; | |
65 | ||
66 | if (hinfo) | |
67 | seg6_hinfo_release(hinfo); | |
68 | } | |
69 | ||
70 | static const struct rhashtable_params rht_params = { | |
71 | .head_offset = offsetof(struct seg6_hmac_info, node), | |
72 | .key_offset = offsetof(struct seg6_hmac_info, hmackeyid), | |
73 | .key_len = sizeof(u32), | |
74 | .automatic_shrinking = true, | |
75 | .obj_cmpfn = seg6_hmac_cmpfn, | |
76 | }; | |
77 | ||
78 | static struct seg6_hmac_algo hmac_algos[] = { | |
79 | { | |
80 | .alg_id = SEG6_HMAC_ALGO_SHA1, | |
81 | .name = "hmac(sha1)", | |
82 | }, | |
83 | { | |
84 | .alg_id = SEG6_HMAC_ALGO_SHA256, | |
85 | .name = "hmac(sha256)", | |
86 | }, | |
87 | }; | |
88 | ||
89 | static struct sr6_tlv_hmac *seg6_get_tlv_hmac(struct ipv6_sr_hdr *srh) | |
90 | { | |
91 | struct sr6_tlv_hmac *tlv; | |
92 | ||
93 | if (srh->hdrlen < (srh->first_segment + 1) * 2 + 5) | |
94 | return NULL; | |
95 | ||
96 | if (!sr_has_hmac(srh)) | |
97 | return NULL; | |
98 | ||
99 | tlv = (struct sr6_tlv_hmac *) | |
100 | ((char *)srh + ((srh->hdrlen + 1) << 3) - 40); | |
101 | ||
102 | if (tlv->tlvhdr.type != SR6_TLV_HMAC || tlv->tlvhdr.len != 38) | |
103 | return NULL; | |
104 | ||
105 | return tlv; | |
106 | } | |
107 | ||
108 | static struct seg6_hmac_algo *__hmac_get_algo(u8 alg_id) | |
109 | { | |
110 | struct seg6_hmac_algo *algo; | |
111 | int i, alg_count; | |
112 | ||
113 | alg_count = sizeof(hmac_algos) / sizeof(struct seg6_hmac_algo); | |
114 | for (i = 0; i < alg_count; i++) { | |
115 | algo = &hmac_algos[i]; | |
116 | if (algo->alg_id == alg_id) | |
117 | return algo; | |
118 | } | |
119 | ||
120 | return NULL; | |
121 | } | |
122 | ||
123 | static int __do_hmac(struct seg6_hmac_info *hinfo, const char *text, u8 psize, | |
124 | u8 *output, int outlen) | |
125 | { | |
126 | struct seg6_hmac_algo *algo; | |
127 | struct crypto_shash *tfm; | |
128 | struct shash_desc *shash; | |
129 | int ret, dgsize; | |
130 | ||
131 | algo = __hmac_get_algo(hinfo->alg_id); | |
132 | if (!algo) | |
133 | return -ENOENT; | |
134 | ||
135 | tfm = *this_cpu_ptr(algo->tfms); | |
136 | ||
137 | dgsize = crypto_shash_digestsize(tfm); | |
138 | if (dgsize > outlen) { | |
139 | pr_debug("sr-ipv6: __do_hmac: digest size too big (%d / %d)\n", | |
140 | dgsize, outlen); | |
141 | return -ENOMEM; | |
142 | } | |
143 | ||
144 | ret = crypto_shash_setkey(tfm, hinfo->secret, hinfo->slen); | |
145 | if (ret < 0) { | |
146 | pr_debug("sr-ipv6: crypto_shash_setkey failed: err %d\n", ret); | |
147 | goto failed; | |
148 | } | |
149 | ||
150 | shash = *this_cpu_ptr(algo->shashs); | |
151 | shash->tfm = tfm; | |
152 | ||
153 | ret = crypto_shash_digest(shash, text, psize, output); | |
154 | if (ret < 0) { | |
155 | pr_debug("sr-ipv6: crypto_shash_digest failed: err %d\n", ret); | |
156 | goto failed; | |
157 | } | |
158 | ||
159 | return dgsize; | |
160 | ||
161 | failed: | |
162 | return ret; | |
163 | } | |
164 | ||
165 | int seg6_hmac_compute(struct seg6_hmac_info *hinfo, struct ipv6_sr_hdr *hdr, | |
166 | struct in6_addr *saddr, u8 *output) | |
167 | { | |
168 | __be32 hmackeyid = cpu_to_be32(hinfo->hmackeyid); | |
169 | u8 tmp_out[SEG6_HMAC_MAX_DIGESTSIZE]; | |
170 | int plen, i, dgsize, wrsize; | |
171 | char *ring, *off; | |
172 | ||
173 | /* a 160-byte buffer for digest output allows to store highest known | |
174 | * hash function (RadioGatun) with up to 1216 bits | |
175 | */ | |
176 | ||
177 | /* saddr(16) + first_seg(1) + cleanup(1) + keyid(4) + seglist(16n) */ | |
178 | plen = 16 + 1 + 1 + 4 + (hdr->first_segment + 1) * 16; | |
179 | ||
180 | /* this limit allows for 14 segments */ | |
181 | if (plen >= SEG6_HMAC_RING_SIZE) | |
182 | return -EMSGSIZE; | |
183 | ||
184 | /* Let's build the HMAC text on the ring buffer. The text is composed | |
185 | * as follows, in order: | |
186 | * | |
187 | * 1. Source IPv6 address (128 bits) | |
188 | * 2. first_segment value (8 bits) | |
189 | * 3. cleanup flag (8 bits: highest bit is cleanup value, others are 0) | |
190 | * 4. HMAC Key ID (32 bits) | |
191 | * 5. All segments in the segments list (n * 128 bits) | |
192 | */ | |
193 | ||
194 | local_bh_disable(); | |
195 | ring = *this_cpu_ptr(hmac_ring); | |
196 | off = ring; | |
197 | ||
198 | /* source address */ | |
199 | memcpy(off, saddr, 16); | |
200 | off += 16; | |
201 | ||
202 | /* first_segment value */ | |
203 | *off++ = hdr->first_segment; | |
204 | ||
205 | /* cleanup flag */ | |
206 | *off++ = !!(sr_has_cleanup(hdr)) << 7; | |
207 | ||
208 | /* HMAC Key ID */ | |
209 | memcpy(off, &hmackeyid, 4); | |
210 | off += 4; | |
211 | ||
212 | /* all segments in the list */ | |
213 | for (i = 0; i < hdr->first_segment + 1; i++) { | |
214 | memcpy(off, hdr->segments + i, 16); | |
215 | off += 16; | |
216 | } | |
217 | ||
218 | dgsize = __do_hmac(hinfo, ring, plen, tmp_out, | |
219 | SEG6_HMAC_MAX_DIGESTSIZE); | |
220 | local_bh_enable(); | |
221 | ||
222 | if (dgsize < 0) | |
223 | return dgsize; | |
224 | ||
225 | wrsize = SEG6_HMAC_FIELD_LEN; | |
226 | if (wrsize > dgsize) | |
227 | wrsize = dgsize; | |
228 | ||
229 | memset(output, 0, SEG6_HMAC_FIELD_LEN); | |
230 | memcpy(output, tmp_out, wrsize); | |
231 | ||
232 | return 0; | |
233 | } | |
234 | EXPORT_SYMBOL(seg6_hmac_compute); | |
235 | ||
236 | /* checks if an incoming SR-enabled packet's HMAC status matches | |
237 | * the incoming policy. | |
238 | * | |
239 | * called with rcu_read_lock() | |
240 | */ | |
241 | bool seg6_hmac_validate_skb(struct sk_buff *skb) | |
242 | { | |
243 | u8 hmac_output[SEG6_HMAC_FIELD_LEN]; | |
244 | struct net *net = dev_net(skb->dev); | |
245 | struct seg6_hmac_info *hinfo; | |
246 | struct sr6_tlv_hmac *tlv; | |
247 | struct ipv6_sr_hdr *srh; | |
248 | struct inet6_dev *idev; | |
249 | ||
250 | idev = __in6_dev_get(skb->dev); | |
251 | ||
252 | srh = (struct ipv6_sr_hdr *)skb_transport_header(skb); | |
253 | ||
254 | tlv = seg6_get_tlv_hmac(srh); | |
255 | ||
256 | /* mandatory check but no tlv */ | |
257 | if (idev->cnf.seg6_require_hmac > 0 && !tlv) | |
258 | return false; | |
259 | ||
260 | /* no check */ | |
261 | if (idev->cnf.seg6_require_hmac < 0) | |
262 | return true; | |
263 | ||
264 | /* check only if present */ | |
265 | if (idev->cnf.seg6_require_hmac == 0 && !tlv) | |
266 | return true; | |
267 | ||
268 | /* now, seg6_require_hmac >= 0 && tlv */ | |
269 | ||
270 | hinfo = seg6_hmac_info_lookup(net, be32_to_cpu(tlv->hmackeyid)); | |
271 | if (!hinfo) | |
272 | return false; | |
273 | ||
274 | if (seg6_hmac_compute(hinfo, srh, &ipv6_hdr(skb)->saddr, hmac_output)) | |
275 | return false; | |
276 | ||
277 | if (memcmp(hmac_output, tlv->hmac, SEG6_HMAC_FIELD_LEN) != 0) | |
278 | return false; | |
279 | ||
280 | return true; | |
281 | } | |
282 | EXPORT_SYMBOL(seg6_hmac_validate_skb); | |
283 | ||
284 | /* called with rcu_read_lock() */ | |
285 | struct seg6_hmac_info *seg6_hmac_info_lookup(struct net *net, u32 key) | |
286 | { | |
287 | struct seg6_pernet_data *sdata = seg6_pernet(net); | |
288 | struct seg6_hmac_info *hinfo; | |
289 | ||
290 | hinfo = rhashtable_lookup_fast(&sdata->hmac_infos, &key, rht_params); | |
291 | ||
292 | return hinfo; | |
293 | } | |
294 | EXPORT_SYMBOL(seg6_hmac_info_lookup); | |
295 | ||
296 | int seg6_hmac_info_add(struct net *net, u32 key, struct seg6_hmac_info *hinfo) | |
297 | { | |
298 | struct seg6_pernet_data *sdata = seg6_pernet(net); | |
299 | int err; | |
300 | ||
301 | err = rhashtable_lookup_insert_fast(&sdata->hmac_infos, &hinfo->node, | |
302 | rht_params); | |
303 | ||
304 | return err; | |
305 | } | |
306 | EXPORT_SYMBOL(seg6_hmac_info_add); | |
307 | ||
308 | int seg6_hmac_info_del(struct net *net, u32 key) | |
309 | { | |
310 | struct seg6_pernet_data *sdata = seg6_pernet(net); | |
311 | struct seg6_hmac_info *hinfo; | |
312 | int err = -ENOENT; | |
313 | ||
314 | hinfo = rhashtable_lookup_fast(&sdata->hmac_infos, &key, rht_params); | |
315 | if (!hinfo) | |
316 | goto out; | |
317 | ||
318 | err = rhashtable_remove_fast(&sdata->hmac_infos, &hinfo->node, | |
319 | rht_params); | |
320 | if (err) | |
321 | goto out; | |
322 | ||
323 | seg6_hinfo_release(hinfo); | |
324 | ||
325 | out: | |
326 | return err; | |
327 | } | |
328 | EXPORT_SYMBOL(seg6_hmac_info_del); | |
329 | ||
330 | int seg6_push_hmac(struct net *net, struct in6_addr *saddr, | |
331 | struct ipv6_sr_hdr *srh) | |
332 | { | |
333 | struct seg6_hmac_info *hinfo; | |
334 | struct sr6_tlv_hmac *tlv; | |
335 | int err = -ENOENT; | |
336 | ||
337 | tlv = seg6_get_tlv_hmac(srh); | |
338 | if (!tlv) | |
339 | return -EINVAL; | |
340 | ||
341 | rcu_read_lock(); | |
342 | ||
343 | hinfo = seg6_hmac_info_lookup(net, be32_to_cpu(tlv->hmackeyid)); | |
344 | if (!hinfo) | |
345 | goto out; | |
346 | ||
347 | memset(tlv->hmac, 0, SEG6_HMAC_FIELD_LEN); | |
348 | err = seg6_hmac_compute(hinfo, srh, saddr, tlv->hmac); | |
349 | ||
350 | out: | |
351 | rcu_read_unlock(); | |
352 | return err; | |
353 | } | |
354 | EXPORT_SYMBOL(seg6_push_hmac); | |
355 | ||
356 | static int seg6_hmac_init_ring(void) | |
357 | { | |
358 | int i; | |
359 | ||
360 | hmac_ring = alloc_percpu(char *); | |
361 | ||
362 | if (!hmac_ring) | |
363 | return -ENOMEM; | |
364 | ||
365 | for_each_possible_cpu(i) { | |
366 | char *ring = kzalloc(SEG6_HMAC_RING_SIZE, GFP_KERNEL); | |
367 | ||
368 | if (!ring) | |
369 | return -ENOMEM; | |
370 | ||
371 | *per_cpu_ptr(hmac_ring, i) = ring; | |
372 | } | |
373 | ||
374 | return 0; | |
375 | } | |
376 | ||
377 | static int seg6_hmac_init_algo(void) | |
378 | { | |
379 | struct seg6_hmac_algo *algo; | |
380 | struct crypto_shash *tfm; | |
381 | struct shash_desc *shash; | |
382 | int i, alg_count, cpu; | |
383 | ||
384 | alg_count = sizeof(hmac_algos) / sizeof(struct seg6_hmac_algo); | |
385 | ||
386 | for (i = 0; i < alg_count; i++) { | |
387 | struct crypto_shash **p_tfm; | |
388 | int shsize; | |
389 | ||
390 | algo = &hmac_algos[i]; | |
391 | algo->tfms = alloc_percpu(struct crypto_shash *); | |
392 | if (!algo->tfms) | |
393 | return -ENOMEM; | |
394 | ||
395 | for_each_possible_cpu(cpu) { | |
396 | tfm = crypto_alloc_shash(algo->name, 0, GFP_KERNEL); | |
397 | if (IS_ERR(tfm)) | |
398 | return PTR_ERR(tfm); | |
399 | p_tfm = per_cpu_ptr(algo->tfms, cpu); | |
400 | *p_tfm = tfm; | |
401 | } | |
402 | ||
403 | p_tfm = this_cpu_ptr(algo->tfms); | |
404 | tfm = *p_tfm; | |
405 | ||
406 | shsize = sizeof(*shash) + crypto_shash_descsize(tfm); | |
407 | ||
408 | algo->shashs = alloc_percpu(struct shash_desc *); | |
409 | if (!algo->shashs) | |
410 | return -ENOMEM; | |
411 | ||
412 | for_each_possible_cpu(cpu) { | |
413 | shash = kzalloc(shsize, GFP_KERNEL); | |
414 | if (!shash) | |
415 | return -ENOMEM; | |
416 | *per_cpu_ptr(algo->shashs, cpu) = shash; | |
417 | } | |
418 | } | |
419 | ||
420 | return 0; | |
421 | } | |
422 | ||
423 | int __init seg6_hmac_init(void) | |
424 | { | |
425 | int ret; | |
426 | ||
427 | ret = seg6_hmac_init_ring(); | |
428 | if (ret < 0) | |
429 | goto out; | |
430 | ||
431 | ret = seg6_hmac_init_algo(); | |
432 | ||
433 | out: | |
434 | return ret; | |
435 | } | |
436 | EXPORT_SYMBOL(seg6_hmac_init); | |
437 | ||
438 | int __net_init seg6_hmac_net_init(struct net *net) | |
439 | { | |
440 | struct seg6_pernet_data *sdata = seg6_pernet(net); | |
441 | ||
442 | rhashtable_init(&sdata->hmac_infos, &rht_params); | |
443 | ||
444 | return 0; | |
445 | } | |
446 | EXPORT_SYMBOL(seg6_hmac_net_init); | |
447 | ||
448 | void seg6_hmac_exit(void) | |
449 | { | |
450 | struct seg6_hmac_algo *algo = NULL; | |
451 | int i, alg_count, cpu; | |
452 | ||
453 | for_each_possible_cpu(i) { | |
454 | char *ring = *per_cpu_ptr(hmac_ring, i); | |
455 | ||
456 | kfree(ring); | |
457 | } | |
458 | free_percpu(hmac_ring); | |
459 | ||
460 | alg_count = sizeof(hmac_algos) / sizeof(struct seg6_hmac_algo); | |
461 | for (i = 0; i < alg_count; i++) { | |
462 | algo = &hmac_algos[i]; | |
463 | for_each_possible_cpu(cpu) { | |
464 | struct crypto_shash *tfm; | |
465 | struct shash_desc *shash; | |
466 | ||
467 | shash = *per_cpu_ptr(algo->shashs, cpu); | |
468 | kfree(shash); | |
469 | tfm = *per_cpu_ptr(algo->tfms, cpu); | |
470 | crypto_free_shash(tfm); | |
471 | } | |
472 | free_percpu(algo->tfms); | |
473 | free_percpu(algo->shashs); | |
474 | } | |
475 | } | |
476 | EXPORT_SYMBOL(seg6_hmac_exit); | |
477 | ||
478 | void __net_exit seg6_hmac_net_exit(struct net *net) | |
479 | { | |
480 | struct seg6_pernet_data *sdata = seg6_pernet(net); | |
481 | ||
482 | rhashtable_free_and_destroy(&sdata->hmac_infos, seg6_free_hi, NULL); | |
483 | } | |
484 | EXPORT_SYMBOL(seg6_hmac_net_exit); |