1 /*-
2 * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
3 *
4 * Copyright (c) 2011 Pawel Jakub Dawidek <[email protected]>
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
47 MALLOC_DECLARE(M_ELI);
48
49 SYSCTL_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 */
54 static u_int g_eli_key_cache_limit = 8192;
55 SYSCTL_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");
57 static uint64_t g_eli_key_cache_hits;
58 SYSCTL_UQUAD(_kern_geom_eli, OID_AUTO, key_cache_hits, CTLFLAG_RW,
59 &g_eli_key_cache_hits, 0, "Key cache hits");
60 static uint64_t g_eli_key_cache_misses;
61 SYSCTL_UQUAD(_kern_geom_eli, OID_AUTO, key_cache_misses, CTLFLAG_RW,
62 &g_eli_key_cache_misses, 0, "Key cache misses");
63
64 static int
g_eli_key_cmp(const struct g_eli_key * a,const struct g_eli_key * b)65 g_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
76 void
g_eli_key_fill(struct g_eli_softc * sc,struct g_eli_key * key,uint64_t keyno)77 g_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
100 RB_PROTOTYPE(g_eli_key_tree, g_eli_key, gek_link, g_eli_key_cmp);
101 RB_GENERATE(g_eli_key_tree, g_eli_key, gek_link, g_eli_key_cmp);
102
103 static struct g_eli_key *
g_eli_key_allocate(struct g_eli_softc * sc,uint64_t keyno)104 g_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
134 static struct g_eli_key *
g_eli_key_find_last(struct g_eli_softc * sc)135 g_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
149 static void
g_eli_key_replace(struct g_eli_softc * sc,struct g_eli_key * key,uint64_t keyno)150 g_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
167 static void
g_eli_key_remove(struct g_eli_softc * sc,struct g_eli_key * key)168 g_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
182 void
g_eli_key_init(struct g_eli_softc * sc)183 g_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
237 void
g_eli_key_destroy(struct g_eli_softc * sc)238 g_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 */
260 uint8_t *
g_eli_key_hold(struct g_eli_softc * sc,off_t offset,size_t blocksize)261 g_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
319 void
g_eli_key_drop(struct g_eli_softc * sc,uint8_t * rawkey)320 g_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