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Note: File does not exist in v3.1.
  1// SPDX-License-Identifier: GPL-2.0-or-later
  2/*
  3 *  SR-IPv6 implementation -- HMAC functions
  4 *
  5 *  Author:
  6 *  David Lebrun <david.lebrun@uclouvain.be>
  7 */
  8
  9#include <linux/errno.h>
 10#include <linux/kernel.h>
 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>
 20#include <linux/rhashtable.h>
 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
 45static DEFINE_PER_CPU(char [SEG6_HMAC_RING_SIZE], hmac_ring);
 46
 47static 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
 54static inline void seg6_hinfo_release(struct seg6_hmac_info *hinfo)
 55{
 56	kfree_rcu(hinfo, rcu);
 57}
 58
 59static 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
 67static 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
 75static 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
 86static 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
105static struct seg6_hmac_algo *__hmac_get_algo(u8 alg_id)
106{
107	struct seg6_hmac_algo *algo;
108	int i, alg_count;
109
110	alg_count = ARRAY_SIZE(hmac_algos);
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
120static 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
158failed:
159	return ret;
160}
161
162int 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
174	/* saddr(16) + first_seg(1) + flags(1) + keyid(4) + seglist(16n) */
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)
186	 * 3. Flags (8 bits)
187	 * 4. HMAC Key ID (32 bits)
188	 * 5. All segments in the segments list (n * 128 bits)
189	 */
190
191	local_bh_disable();
192	ring = this_cpu_ptr(hmac_ring);
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
202	/* flags */
203	*off++ = hdr->flags;
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}
231EXPORT_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 */
238bool 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}
279EXPORT_SYMBOL(seg6_hmac_validate_skb);
280
281/* called with rcu_read_lock() */
282struct 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}
291EXPORT_SYMBOL(seg6_hmac_info_lookup);
292
293int 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}
303EXPORT_SYMBOL(seg6_hmac_info_add);
304
305int 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
322out:
323	return err;
324}
325EXPORT_SYMBOL(seg6_hmac_info_del);
326
327int 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
347out:
348	rcu_read_unlock();
349	return err;
350}
351EXPORT_SYMBOL(seg6_push_hmac);
352
353static 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
360	alg_count = ARRAY_SIZE(hmac_algos);
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) {
372			tfm = crypto_alloc_shash(algo->name, 0, 0);
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
379		p_tfm = raw_cpu_ptr(algo->tfms);
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) {
389			shash = kzalloc_node(shsize, GFP_KERNEL,
390					     cpu_to_node(cpu));
391			if (!shash)
392				return -ENOMEM;
393			*per_cpu_ptr(algo->shashs, cpu) = shash;
394		}
395	}
396
397	return 0;
398}
399
400int __init seg6_hmac_init(void)
401{
402	return seg6_hmac_init_algo();
403}
404EXPORT_SYMBOL(seg6_hmac_init);
405
406int __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}
414EXPORT_SYMBOL(seg6_hmac_net_init);
415
416void seg6_hmac_exit(void)
417{
418	struct seg6_hmac_algo *algo = NULL;
419	int i, alg_count, cpu;
420
421	alg_count = ARRAY_SIZE(hmac_algos);
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}
437EXPORT_SYMBOL(seg6_hmac_exit);
438
439void __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}
445EXPORT_SYMBOL(seg6_hmac_net_exit);