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2874c5fd | 1 | // SPDX-License-Identifier: GPL-2.0-or-later |
bf355b8d DL |
2 | /* |
3 | * SR-IPv6 implementation -- HMAC functions | |
4 | * | |
5 | * Author: | |
6 | * David Lebrun <david.lebrun@uclouvain.be> | |
bf355b8d DL |
7 | */ |
8 | ||
9 | #include <linux/errno.h> | |
6391c4f6 | 10 | #include <linux/kernel.h> |
bf355b8d DL |
11 | #include <linux/types.h> |
12 | #include <linux/socket.h> | |
13 | #include <linux/sockios.h> | |
14 | #include <linux/net.h> | |
15 | #include <linux/netdevice.h> | |
16 | #include <linux/in6.h> | |
17 | #include <linux/icmpv6.h> | |
18 | #include <linux/mroute6.h> | |
19 | #include <linux/slab.h> | |
0eb71a9d | 20 | #include <linux/rhashtable.h> |
bf355b8d DL |
21 | |
22 | #include <linux/netfilter.h> | |
23 | #include <linux/netfilter_ipv6.h> | |
24 | ||
25 | #include <net/sock.h> | |
26 | #include <net/snmp.h> | |
27 | ||
28 | #include <net/ipv6.h> | |
29 | #include <net/protocol.h> | |
30 | #include <net/transp_v6.h> | |
31 | #include <net/rawv6.h> | |
32 | #include <net/ndisc.h> | |
33 | #include <net/ip6_route.h> | |
34 | #include <net/addrconf.h> | |
35 | #include <net/xfrm.h> | |
36 | ||
37 | #include <linux/cryptohash.h> | |
38 | #include <crypto/hash.h> | |
39 | #include <crypto/sha.h> | |
40 | #include <net/seg6.h> | |
41 | #include <net/genetlink.h> | |
42 | #include <net/seg6_hmac.h> | |
43 | #include <linux/random.h> | |
44 | ||
717ac5ce | 45 | static DEFINE_PER_CPU(char [SEG6_HMAC_RING_SIZE], hmac_ring); |
bf355b8d DL |
46 | |
47 | static int seg6_hmac_cmpfn(struct rhashtable_compare_arg *arg, const void *obj) | |
48 | { | |
49 | const struct seg6_hmac_info *hinfo = obj; | |
50 | ||
51 | return (hinfo->hmackeyid != *(__u32 *)arg->key); | |
52 | } | |
53 | ||
54 | static inline void seg6_hinfo_release(struct seg6_hmac_info *hinfo) | |
55 | { | |
56 | kfree_rcu(hinfo, rcu); | |
57 | } | |
58 | ||
59 | static void seg6_free_hi(void *ptr, void *arg) | |
60 | { | |
61 | struct seg6_hmac_info *hinfo = (struct seg6_hmac_info *)ptr; | |
62 | ||
63 | if (hinfo) | |
64 | seg6_hinfo_release(hinfo); | |
65 | } | |
66 | ||
67 | static const struct rhashtable_params rht_params = { | |
68 | .head_offset = offsetof(struct seg6_hmac_info, node), | |
69 | .key_offset = offsetof(struct seg6_hmac_info, hmackeyid), | |
70 | .key_len = sizeof(u32), | |
71 | .automatic_shrinking = true, | |
72 | .obj_cmpfn = seg6_hmac_cmpfn, | |
73 | }; | |
74 | ||
75 | static struct seg6_hmac_algo hmac_algos[] = { | |
76 | { | |
77 | .alg_id = SEG6_HMAC_ALGO_SHA1, | |
78 | .name = "hmac(sha1)", | |
79 | }, | |
80 | { | |
81 | .alg_id = SEG6_HMAC_ALGO_SHA256, | |
82 | .name = "hmac(sha256)", | |
83 | }, | |
84 | }; | |
85 | ||
86 | static struct sr6_tlv_hmac *seg6_get_tlv_hmac(struct ipv6_sr_hdr *srh) | |
87 | { | |
88 | struct sr6_tlv_hmac *tlv; | |
89 | ||
90 | if (srh->hdrlen < (srh->first_segment + 1) * 2 + 5) | |
91 | return NULL; | |
92 | ||
93 | if (!sr_has_hmac(srh)) | |
94 | return NULL; | |
95 | ||
96 | tlv = (struct sr6_tlv_hmac *) | |
97 | ((char *)srh + ((srh->hdrlen + 1) << 3) - 40); | |
98 | ||
99 | if (tlv->tlvhdr.type != SR6_TLV_HMAC || tlv->tlvhdr.len != 38) | |
100 | return NULL; | |
101 | ||
102 | return tlv; | |
103 | } | |
104 | ||
105 | static struct seg6_hmac_algo *__hmac_get_algo(u8 alg_id) | |
106 | { | |
107 | struct seg6_hmac_algo *algo; | |
108 | int i, alg_count; | |
109 | ||
6391c4f6 | 110 | alg_count = ARRAY_SIZE(hmac_algos); |
bf355b8d DL |
111 | for (i = 0; i < alg_count; i++) { |
112 | algo = &hmac_algos[i]; | |
113 | if (algo->alg_id == alg_id) | |
114 | return algo; | |
115 | } | |
116 | ||
117 | return NULL; | |
118 | } | |
119 | ||
120 | static int __do_hmac(struct seg6_hmac_info *hinfo, const char *text, u8 psize, | |
121 | u8 *output, int outlen) | |
122 | { | |
123 | struct seg6_hmac_algo *algo; | |
124 | struct crypto_shash *tfm; | |
125 | struct shash_desc *shash; | |
126 | int ret, dgsize; | |
127 | ||
128 | algo = __hmac_get_algo(hinfo->alg_id); | |
129 | if (!algo) | |
130 | return -ENOENT; | |
131 | ||
132 | tfm = *this_cpu_ptr(algo->tfms); | |
133 | ||
134 | dgsize = crypto_shash_digestsize(tfm); | |
135 | if (dgsize > outlen) { | |
136 | pr_debug("sr-ipv6: __do_hmac: digest size too big (%d / %d)\n", | |
137 | dgsize, outlen); | |
138 | return -ENOMEM; | |
139 | } | |
140 | ||
141 | ret = crypto_shash_setkey(tfm, hinfo->secret, hinfo->slen); | |
142 | if (ret < 0) { | |
143 | pr_debug("sr-ipv6: crypto_shash_setkey failed: err %d\n", ret); | |
144 | goto failed; | |
145 | } | |
146 | ||
147 | shash = *this_cpu_ptr(algo->shashs); | |
148 | shash->tfm = tfm; | |
149 | ||
150 | ret = crypto_shash_digest(shash, text, psize, output); | |
151 | if (ret < 0) { | |
152 | pr_debug("sr-ipv6: crypto_shash_digest failed: err %d\n", ret); | |
153 | goto failed; | |
154 | } | |
155 | ||
156 | return dgsize; | |
157 | ||
158 | failed: | |
159 | return ret; | |
160 | } | |
161 | ||
162 | int seg6_hmac_compute(struct seg6_hmac_info *hinfo, struct ipv6_sr_hdr *hdr, | |
163 | struct in6_addr *saddr, u8 *output) | |
164 | { | |
165 | __be32 hmackeyid = cpu_to_be32(hinfo->hmackeyid); | |
166 | u8 tmp_out[SEG6_HMAC_MAX_DIGESTSIZE]; | |
167 | int plen, i, dgsize, wrsize; | |
168 | char *ring, *off; | |
169 | ||
170 | /* a 160-byte buffer for digest output allows to store highest known | |
171 | * hash function (RadioGatun) with up to 1216 bits | |
172 | */ | |
173 | ||
013e8167 | 174 | /* saddr(16) + first_seg(1) + flags(1) + keyid(4) + seglist(16n) */ |
bf355b8d DL |
175 | plen = 16 + 1 + 1 + 4 + (hdr->first_segment + 1) * 16; |
176 | ||
177 | /* this limit allows for 14 segments */ | |
178 | if (plen >= SEG6_HMAC_RING_SIZE) | |
179 | return -EMSGSIZE; | |
180 | ||
181 | /* Let's build the HMAC text on the ring buffer. The text is composed | |
182 | * as follows, in order: | |
183 | * | |
184 | * 1. Source IPv6 address (128 bits) | |
185 | * 2. first_segment value (8 bits) | |
013e8167 | 186 | * 3. Flags (8 bits) |
bf355b8d DL |
187 | * 4. HMAC Key ID (32 bits) |
188 | * 5. All segments in the segments list (n * 128 bits) | |
189 | */ | |
190 | ||
191 | local_bh_disable(); | |
717ac5ce | 192 | ring = this_cpu_ptr(hmac_ring); |
bf355b8d DL |
193 | off = ring; |
194 | ||
195 | /* source address */ | |
196 | memcpy(off, saddr, 16); | |
197 | off += 16; | |
198 | ||
199 | /* first_segment value */ | |
200 | *off++ = hdr->first_segment; | |
201 | ||
013e8167 DL |
202 | /* flags */ |
203 | *off++ = hdr->flags; | |
bf355b8d DL |
204 | |
205 | /* HMAC Key ID */ | |
206 | memcpy(off, &hmackeyid, 4); | |
207 | off += 4; | |
208 | ||
209 | /* all segments in the list */ | |
210 | for (i = 0; i < hdr->first_segment + 1; i++) { | |
211 | memcpy(off, hdr->segments + i, 16); | |
212 | off += 16; | |
213 | } | |
214 | ||
215 | dgsize = __do_hmac(hinfo, ring, plen, tmp_out, | |
216 | SEG6_HMAC_MAX_DIGESTSIZE); | |
217 | local_bh_enable(); | |
218 | ||
219 | if (dgsize < 0) | |
220 | return dgsize; | |
221 | ||
222 | wrsize = SEG6_HMAC_FIELD_LEN; | |
223 | if (wrsize > dgsize) | |
224 | wrsize = dgsize; | |
225 | ||
226 | memset(output, 0, SEG6_HMAC_FIELD_LEN); | |
227 | memcpy(output, tmp_out, wrsize); | |
228 | ||
229 | return 0; | |
230 | } | |
231 | EXPORT_SYMBOL(seg6_hmac_compute); | |
232 | ||
233 | /* checks if an incoming SR-enabled packet's HMAC status matches | |
234 | * the incoming policy. | |
235 | * | |
236 | * called with rcu_read_lock() | |
237 | */ | |
238 | bool seg6_hmac_validate_skb(struct sk_buff *skb) | |
239 | { | |
240 | u8 hmac_output[SEG6_HMAC_FIELD_LEN]; | |
241 | struct net *net = dev_net(skb->dev); | |
242 | struct seg6_hmac_info *hinfo; | |
243 | struct sr6_tlv_hmac *tlv; | |
244 | struct ipv6_sr_hdr *srh; | |
245 | struct inet6_dev *idev; | |
246 | ||
247 | idev = __in6_dev_get(skb->dev); | |
248 | ||
249 | srh = (struct ipv6_sr_hdr *)skb_transport_header(skb); | |
250 | ||
251 | tlv = seg6_get_tlv_hmac(srh); | |
252 | ||
253 | /* mandatory check but no tlv */ | |
254 | if (idev->cnf.seg6_require_hmac > 0 && !tlv) | |
255 | return false; | |
256 | ||
257 | /* no check */ | |
258 | if (idev->cnf.seg6_require_hmac < 0) | |
259 | return true; | |
260 | ||
261 | /* check only if present */ | |
262 | if (idev->cnf.seg6_require_hmac == 0 && !tlv) | |
263 | return true; | |
264 | ||
265 | /* now, seg6_require_hmac >= 0 && tlv */ | |
266 | ||
267 | hinfo = seg6_hmac_info_lookup(net, be32_to_cpu(tlv->hmackeyid)); | |
268 | if (!hinfo) | |
269 | return false; | |
270 | ||
271 | if (seg6_hmac_compute(hinfo, srh, &ipv6_hdr(skb)->saddr, hmac_output)) | |
272 | return false; | |
273 | ||
274 | if (memcmp(hmac_output, tlv->hmac, SEG6_HMAC_FIELD_LEN) != 0) | |
275 | return false; | |
276 | ||
277 | return true; | |
278 | } | |
279 | EXPORT_SYMBOL(seg6_hmac_validate_skb); | |
280 | ||
281 | /* called with rcu_read_lock() */ | |
282 | struct seg6_hmac_info *seg6_hmac_info_lookup(struct net *net, u32 key) | |
283 | { | |
284 | struct seg6_pernet_data *sdata = seg6_pernet(net); | |
285 | struct seg6_hmac_info *hinfo; | |
286 | ||
287 | hinfo = rhashtable_lookup_fast(&sdata->hmac_infos, &key, rht_params); | |
288 | ||
289 | return hinfo; | |
290 | } | |
291 | EXPORT_SYMBOL(seg6_hmac_info_lookup); | |
292 | ||
293 | int seg6_hmac_info_add(struct net *net, u32 key, struct seg6_hmac_info *hinfo) | |
294 | { | |
295 | struct seg6_pernet_data *sdata = seg6_pernet(net); | |
296 | int err; | |
297 | ||
298 | err = rhashtable_lookup_insert_fast(&sdata->hmac_infos, &hinfo->node, | |
299 | rht_params); | |
300 | ||
301 | return err; | |
302 | } | |
303 | EXPORT_SYMBOL(seg6_hmac_info_add); | |
304 | ||
305 | int seg6_hmac_info_del(struct net *net, u32 key) | |
306 | { | |
307 | struct seg6_pernet_data *sdata = seg6_pernet(net); | |
308 | struct seg6_hmac_info *hinfo; | |
309 | int err = -ENOENT; | |
310 | ||
311 | hinfo = rhashtable_lookup_fast(&sdata->hmac_infos, &key, rht_params); | |
312 | if (!hinfo) | |
313 | goto out; | |
314 | ||
315 | err = rhashtable_remove_fast(&sdata->hmac_infos, &hinfo->node, | |
316 | rht_params); | |
317 | if (err) | |
318 | goto out; | |
319 | ||
320 | seg6_hinfo_release(hinfo); | |
321 | ||
322 | out: | |
323 | return err; | |
324 | } | |
325 | EXPORT_SYMBOL(seg6_hmac_info_del); | |
326 | ||
327 | int seg6_push_hmac(struct net *net, struct in6_addr *saddr, | |
328 | struct ipv6_sr_hdr *srh) | |
329 | { | |
330 | struct seg6_hmac_info *hinfo; | |
331 | struct sr6_tlv_hmac *tlv; | |
332 | int err = -ENOENT; | |
333 | ||
334 | tlv = seg6_get_tlv_hmac(srh); | |
335 | if (!tlv) | |
336 | return -EINVAL; | |
337 | ||
338 | rcu_read_lock(); | |
339 | ||
340 | hinfo = seg6_hmac_info_lookup(net, be32_to_cpu(tlv->hmackeyid)); | |
341 | if (!hinfo) | |
342 | goto out; | |
343 | ||
344 | memset(tlv->hmac, 0, SEG6_HMAC_FIELD_LEN); | |
345 | err = seg6_hmac_compute(hinfo, srh, saddr, tlv->hmac); | |
346 | ||
347 | out: | |
348 | rcu_read_unlock(); | |
349 | return err; | |
350 | } | |
351 | EXPORT_SYMBOL(seg6_push_hmac); | |
352 | ||
bf355b8d DL |
353 | static int seg6_hmac_init_algo(void) |
354 | { | |
355 | struct seg6_hmac_algo *algo; | |
356 | struct crypto_shash *tfm; | |
357 | struct shash_desc *shash; | |
358 | int i, alg_count, cpu; | |
359 | ||
6391c4f6 | 360 | alg_count = ARRAY_SIZE(hmac_algos); |
bf355b8d DL |
361 | |
362 | for (i = 0; i < alg_count; i++) { | |
363 | struct crypto_shash **p_tfm; | |
364 | int shsize; | |
365 | ||
366 | algo = &hmac_algos[i]; | |
367 | algo->tfms = alloc_percpu(struct crypto_shash *); | |
368 | if (!algo->tfms) | |
369 | return -ENOMEM; | |
370 | ||
371 | for_each_possible_cpu(cpu) { | |
fc9c2029 | 372 | tfm = crypto_alloc_shash(algo->name, 0, 0); |
bf355b8d DL |
373 | if (IS_ERR(tfm)) |
374 | return PTR_ERR(tfm); | |
375 | p_tfm = per_cpu_ptr(algo->tfms, cpu); | |
376 | *p_tfm = tfm; | |
377 | } | |
378 | ||
fa79581e | 379 | p_tfm = raw_cpu_ptr(algo->tfms); |
bf355b8d DL |
380 | tfm = *p_tfm; |
381 | ||
382 | shsize = sizeof(*shash) + crypto_shash_descsize(tfm); | |
383 | ||
384 | algo->shashs = alloc_percpu(struct shash_desc *); | |
385 | if (!algo->shashs) | |
386 | return -ENOMEM; | |
387 | ||
388 | for_each_possible_cpu(cpu) { | |
9ca677b1 ED |
389 | shash = kzalloc_node(shsize, GFP_KERNEL, |
390 | cpu_to_node(cpu)); | |
bf355b8d DL |
391 | if (!shash) |
392 | return -ENOMEM; | |
393 | *per_cpu_ptr(algo->shashs, cpu) = shash; | |
394 | } | |
395 | } | |
396 | ||
397 | return 0; | |
398 | } | |
399 | ||
400 | int __init seg6_hmac_init(void) | |
401 | { | |
717ac5ce | 402 | return seg6_hmac_init_algo(); |
bf355b8d DL |
403 | } |
404 | EXPORT_SYMBOL(seg6_hmac_init); | |
405 | ||
406 | int __net_init seg6_hmac_net_init(struct net *net) | |
407 | { | |
408 | struct seg6_pernet_data *sdata = seg6_pernet(net); | |
409 | ||
410 | rhashtable_init(&sdata->hmac_infos, &rht_params); | |
411 | ||
412 | return 0; | |
413 | } | |
414 | EXPORT_SYMBOL(seg6_hmac_net_init); | |
415 | ||
416 | void seg6_hmac_exit(void) | |
417 | { | |
418 | struct seg6_hmac_algo *algo = NULL; | |
419 | int i, alg_count, cpu; | |
420 | ||
6391c4f6 | 421 | alg_count = ARRAY_SIZE(hmac_algos); |
bf355b8d DL |
422 | for (i = 0; i < alg_count; i++) { |
423 | algo = &hmac_algos[i]; | |
424 | for_each_possible_cpu(cpu) { | |
425 | struct crypto_shash *tfm; | |
426 | struct shash_desc *shash; | |
427 | ||
428 | shash = *per_cpu_ptr(algo->shashs, cpu); | |
429 | kfree(shash); | |
430 | tfm = *per_cpu_ptr(algo->tfms, cpu); | |
431 | crypto_free_shash(tfm); | |
432 | } | |
433 | free_percpu(algo->tfms); | |
434 | free_percpu(algo->shashs); | |
435 | } | |
436 | } | |
437 | EXPORT_SYMBOL(seg6_hmac_exit); | |
438 | ||
439 | void __net_exit seg6_hmac_net_exit(struct net *net) | |
440 | { | |
441 | struct seg6_pernet_data *sdata = seg6_pernet(net); | |
442 | ||
443 | rhashtable_free_and_destroy(&sdata->hmac_infos, seg6_free_hi, NULL); | |
444 | } | |
445 | EXPORT_SYMBOL(seg6_hmac_net_exit); |