1/*-
2 * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
3 *
4 * Copyright (c) 2011 Pawel Jakub Dawidek <pawel@dawidek.net>
5 * All rights reserved.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 * 1. Redistributions of source code must retain the above copyright
11 *    notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 *    notice, this list of conditions and the following disclaimer in the
14 *    documentation and/or other materials provided with the distribution.
15 *
16 * THIS SOFTWARE IS PROVIDED BY THE AUTHORS AND CONTRIBUTORS ``AS IS'' AND
17 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
18 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
19 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHORS OR CONTRIBUTORS BE LIABLE
20 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
21 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
22 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
23 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
24 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
25 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
26 * SUCH DAMAGE.
27 */
28
29#include <sys/cdefs.h>
30__FBSDID("$FreeBSD$");
31
32#include <sys/param.h>
33#ifdef _KERNEL
34#include <sys/kernel.h>
35#include <sys/malloc.h>
36#include <sys/sysctl.h>
37#include <sys/systm.h>
38#endif /* _KERNEL */
39#include <sys/queue.h>
40#include <sys/tree.h>
41
42#include <geom/geom.h>
43
44#include <geom/eli/g_eli.h>
45
46#ifdef _KERNEL
47MALLOC_DECLARE(M_ELI);
48
49SYSCTL_DECL(_kern_geom_eli);
50/*
51 * The default limit (8192 keys) will allow to cache all keys for 4TB
52 * provider with 512 bytes sectors and will take around 1MB of memory.
53 */
54static u_int g_eli_key_cache_limit = 8192;
55SYSCTL_UINT(_kern_geom_eli, OID_AUTO, key_cache_limit, CTLFLAG_RDTUN,
56    &g_eli_key_cache_limit, 0, "Maximum number of encryption keys to cache");
57static uint64_t g_eli_key_cache_hits;
58SYSCTL_UQUAD(_kern_geom_eli, OID_AUTO, key_cache_hits, CTLFLAG_RW,
59    &g_eli_key_cache_hits, 0, "Key cache hits");
60static uint64_t g_eli_key_cache_misses;
61SYSCTL_UQUAD(_kern_geom_eli, OID_AUTO, key_cache_misses, CTLFLAG_RW,
62    &g_eli_key_cache_misses, 0, "Key cache misses");
63
64static int
65g_eli_key_cmp(const struct g_eli_key *a, const struct g_eli_key *b)
66{
67
68	if (a->gek_keyno > b->gek_keyno)
69		return (1);
70	else if (a->gek_keyno < b->gek_keyno)
71		return (-1);
72	return (0);
73}
74#endif /* _KERNEL */
75
76void
77g_eli_key_fill(struct g_eli_softc *sc, struct g_eli_key *key, uint64_t keyno)
78{
79	const uint8_t *ekey;
80	struct {
81		char magic[4];
82		uint8_t keyno[8];
83	} __packed hmacdata;
84
85	if ((sc->sc_flags & G_ELI_FLAG_ENC_IVKEY) != 0)
86		ekey = sc->sc_mkey;
87	else
88		ekey = sc->sc_ekey;
89
90	bcopy("ekey", hmacdata.magic, 4);
91	le64enc(hmacdata.keyno, keyno);
92	g_eli_crypto_hmac(ekey, G_ELI_MAXKEYLEN, (uint8_t *)&hmacdata,
93	    sizeof(hmacdata), key->gek_key, 0);
94	key->gek_keyno = keyno;
95	key->gek_count = 0;
96	key->gek_magic = G_ELI_KEY_MAGIC;
97}
98
99#ifdef _KERNEL
100RB_PROTOTYPE(g_eli_key_tree, g_eli_key, gek_link, g_eli_key_cmp);
101RB_GENERATE(g_eli_key_tree, g_eli_key, gek_link, g_eli_key_cmp);
102
103static struct g_eli_key *
104g_eli_key_allocate(struct g_eli_softc *sc, uint64_t keyno)
105{
106	struct g_eli_key *key, *ekey, keysearch;
107
108	mtx_assert(&sc->sc_ekeys_lock, MA_OWNED);
109	mtx_unlock(&sc->sc_ekeys_lock);
110
111	key = malloc(sizeof(*key), M_ELI, M_WAITOK);
112	g_eli_key_fill(sc, key, keyno);
113
114	mtx_lock(&sc->sc_ekeys_lock);
115	/*
116	 * Recheck if the key wasn't added while we weren't holding the lock.
117	 */
118	keysearch.gek_keyno = keyno;
119	ekey = RB_FIND(g_eli_key_tree, &sc->sc_ekeys_tree, &keysearch);
120	if (ekey != NULL) {
121		explicit_bzero(key, sizeof(*key));
122		free(key, M_ELI);
123		key = ekey;
124		TAILQ_REMOVE(&sc->sc_ekeys_queue, key, gek_next);
125	} else {
126		RB_INSERT(g_eli_key_tree, &sc->sc_ekeys_tree, key);
127		sc->sc_ekeys_allocated++;
128	}
129	TAILQ_INSERT_TAIL(&sc->sc_ekeys_queue, key, gek_next);
130
131	return (key);
132}
133
134static struct g_eli_key *
135g_eli_key_find_last(struct g_eli_softc *sc)
136{
137	struct g_eli_key *key;
138
139	mtx_assert(&sc->sc_ekeys_lock, MA_OWNED);
140
141	TAILQ_FOREACH(key, &sc->sc_ekeys_queue, gek_next) {
142		if (key->gek_count == 0)
143			break;
144	}
145
146	return (key);
147}
148
149static void
150g_eli_key_replace(struct g_eli_softc *sc, struct g_eli_key *key, uint64_t keyno)
151{
152
153	mtx_assert(&sc->sc_ekeys_lock, MA_OWNED);
154	KASSERT(key->gek_magic == G_ELI_KEY_MAGIC, ("Invalid magic."));
155
156	RB_REMOVE(g_eli_key_tree, &sc->sc_ekeys_tree, key);
157	TAILQ_REMOVE(&sc->sc_ekeys_queue, key, gek_next);
158
159	KASSERT(key->gek_count == 0, ("gek_count=%d", key->gek_count));
160
161	g_eli_key_fill(sc, key, keyno);
162
163	RB_INSERT(g_eli_key_tree, &sc->sc_ekeys_tree, key);
164	TAILQ_INSERT_TAIL(&sc->sc_ekeys_queue, key, gek_next);
165}
166
167static void
168g_eli_key_remove(struct g_eli_softc *sc, struct g_eli_key *key)
169{
170
171	mtx_assert(&sc->sc_ekeys_lock, MA_OWNED);
172	KASSERT(key->gek_magic == G_ELI_KEY_MAGIC, ("Invalid magic."));
173	KASSERT(key->gek_count == 0, ("gek_count=%d", key->gek_count));
174
175	RB_REMOVE(g_eli_key_tree, &sc->sc_ekeys_tree, key);
176	TAILQ_REMOVE(&sc->sc_ekeys_queue, key, gek_next);
177	sc->sc_ekeys_allocated--;
178	explicit_bzero(key, sizeof(*key));
179	free(key, M_ELI);
180}
181
182void
183g_eli_key_init(struct g_eli_softc *sc)
184{
185	uint8_t *mkey;
186
187	mtx_lock(&sc->sc_ekeys_lock);
188
189	mkey = sc->sc_mkey + sizeof(sc->sc_ivkey);
190	if ((sc->sc_flags & G_ELI_FLAG_AUTH) == 0)
191		bcopy(mkey, sc->sc_ekey, G_ELI_DATAKEYLEN);
192	else {
193		/*
194		 * The encryption key is: ekey = HMAC_SHA512(Data-Key, 0x10)
195		 */
196		g_eli_crypto_hmac(mkey, G_ELI_MAXKEYLEN, "\x10", 1,
197		    sc->sc_ekey, 0);
198	}
199
200	if ((sc->sc_flags & G_ELI_FLAG_SINGLE_KEY) != 0) {
201		sc->sc_ekeys_total = 1;
202		sc->sc_ekeys_allocated = 0;
203	} else {
204		off_t mediasize;
205		size_t blocksize;
206
207		if ((sc->sc_flags & G_ELI_FLAG_AUTH) != 0) {
208			struct g_provider *pp;
209
210			pp = LIST_FIRST(&sc->sc_geom->consumer)->provider;
211			mediasize = pp->mediasize;
212			blocksize = pp->sectorsize;
213		} else {
214			mediasize = sc->sc_mediasize;
215			blocksize = sc->sc_sectorsize;
216		}
217		sc->sc_ekeys_total =
218		    ((mediasize - 1) >> G_ELI_KEY_SHIFT) / blocksize + 1;
219		sc->sc_ekeys_allocated = 0;
220		TAILQ_INIT(&sc->sc_ekeys_queue);
221		RB_INIT(&sc->sc_ekeys_tree);
222		if (sc->sc_ekeys_total <= g_eli_key_cache_limit) {
223			uint64_t keyno;
224
225			for (keyno = 0; keyno < sc->sc_ekeys_total; keyno++)
226				(void)g_eli_key_allocate(sc, keyno);
227			KASSERT(sc->sc_ekeys_total == sc->sc_ekeys_allocated,
228			    ("sc_ekeys_total=%ju != sc_ekeys_allocated=%ju",
229			    (uintmax_t)sc->sc_ekeys_total,
230			    (uintmax_t)sc->sc_ekeys_allocated));
231		}
232	}
233
234	mtx_unlock(&sc->sc_ekeys_lock);
235}
236
237void
238g_eli_key_destroy(struct g_eli_softc *sc)
239{
240
241	mtx_lock(&sc->sc_ekeys_lock);
242	if ((sc->sc_flags & G_ELI_FLAG_SINGLE_KEY) != 0) {
243		explicit_bzero(sc->sc_ekey, sizeof(sc->sc_ekey));
244	} else {
245		struct g_eli_key *key;
246
247		while ((key = TAILQ_FIRST(&sc->sc_ekeys_queue)) != NULL)
248			g_eli_key_remove(sc, key);
249		TAILQ_INIT(&sc->sc_ekeys_queue);
250		RB_INIT(&sc->sc_ekeys_tree);
251	}
252	mtx_unlock(&sc->sc_ekeys_lock);
253}
254
255/*
256 * Select encryption key. If G_ELI_FLAG_SINGLE_KEY is present we only have one
257 * key available for all the data. If the flag is not present select the key
258 * based on data offset.
259 */
260uint8_t *
261g_eli_key_hold(struct g_eli_softc *sc, off_t offset, size_t blocksize)
262{
263	struct g_eli_key *key, keysearch;
264	uint64_t keyno;
265
266	if ((sc->sc_flags & G_ELI_FLAG_SINGLE_KEY) != 0)
267		return (sc->sc_ekey);
268
269	/* We switch key every 2^G_ELI_KEY_SHIFT blocks. */
270	keyno = (offset >> G_ELI_KEY_SHIFT) / blocksize;
271
272	KASSERT(keyno < sc->sc_ekeys_total,
273	    ("%s: keyno=%ju >= sc_ekeys_total=%ju",
274	    __func__, (uintmax_t)keyno, (uintmax_t)sc->sc_ekeys_total));
275
276	keysearch.gek_keyno = keyno;
277
278	if (sc->sc_ekeys_total == sc->sc_ekeys_allocated) {
279		/* We have all the keys, so avoid some overhead. */
280		key = RB_FIND(g_eli_key_tree, &sc->sc_ekeys_tree, &keysearch);
281		KASSERT(key != NULL, ("No key %ju found.", (uintmax_t)keyno));
282		KASSERT(key->gek_magic == G_ELI_KEY_MAGIC,
283		    ("Invalid key magic."));
284		return (key->gek_key);
285	}
286
287	mtx_lock(&sc->sc_ekeys_lock);
288	key = RB_FIND(g_eli_key_tree, &sc->sc_ekeys_tree, &keysearch);
289	if (key != NULL) {
290		g_eli_key_cache_hits++;
291		TAILQ_REMOVE(&sc->sc_ekeys_queue, key, gek_next);
292		TAILQ_INSERT_TAIL(&sc->sc_ekeys_queue, key, gek_next);
293	} else {
294		/*
295		 * No key in cache, find the least recently unreferenced key
296		 * or allocate one if we haven't reached our limit yet.
297		 */
298		if (sc->sc_ekeys_allocated < g_eli_key_cache_limit) {
299			key = g_eli_key_allocate(sc, keyno);
300		} else {
301			g_eli_key_cache_misses++;
302			key = g_eli_key_find_last(sc);
303			if (key != NULL) {
304				g_eli_key_replace(sc, key, keyno);
305			} else {
306				/* All keys are referenced? Allocate one. */
307				key = g_eli_key_allocate(sc, keyno);
308			}
309		}
310	}
311	key->gek_count++;
312	mtx_unlock(&sc->sc_ekeys_lock);
313
314	KASSERT(key->gek_magic == G_ELI_KEY_MAGIC, ("Invalid key magic."));
315
316	return (key->gek_key);
317}
318
319void
320g_eli_key_drop(struct g_eli_softc *sc, uint8_t *rawkey)
321{
322	struct g_eli_key *key = (struct g_eli_key *)rawkey;
323
324	if ((sc->sc_flags & G_ELI_FLAG_SINGLE_KEY) != 0)
325		return;
326
327	KASSERT(key->gek_magic == G_ELI_KEY_MAGIC, ("Invalid key magic."));
328
329	if (sc->sc_ekeys_total == sc->sc_ekeys_allocated)
330		return;
331
332	mtx_lock(&sc->sc_ekeys_lock);
333	KASSERT(key->gek_count > 0, ("key->gek_count=%d", key->gek_count));
334	key->gek_count--;
335	while (sc->sc_ekeys_allocated > g_eli_key_cache_limit) {
336		key = g_eli_key_find_last(sc);
337		if (key == NULL)
338			break;
339		g_eli_key_remove(sc, key);
340	}
341	mtx_unlock(&sc->sc_ekeys_lock);
342}
343#endif /* _KERNEL */
344