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4f22f405 | 1 | /* |
c8147d37 | 2 | * Copyright 2000-2019 The OpenSSL Project Authors. All Rights Reserved. |
9b141126 | 3 | * |
367ace68 | 4 | * Licensed under the Apache License 2.0 (the "License"). You may not use |
4f22f405 RS |
5 | * this file except in compliance with the License. You can obtain a copy |
6 | * in the file LICENSE in the source distribution or at | |
7 | * https://www.openssl.org/source/license.html | |
9b141126 UM |
8 | */ |
9 | ||
6e810f2d | 10 | #include <openssl/trace.h> |
b39fc560 | 11 | #include "internal/cryptlib.h" |
c62b26fd | 12 | #include "bn_lcl.h" |
9b141126 | 13 | |
3a83462d MC |
14 | /*- |
15 | * TODO list | |
5c98b2ca GT |
16 | * |
17 | * 1. Check a bunch of "(words+1)" type hacks in various bignum functions and | |
18 | * check they can be safely removed. | |
5c98b2ca | 19 | * - Check +1 and other ugliness in BN_from_montgomery() |
5c98b2ca GT |
20 | * |
21 | * 2. Consider allowing a BN_new_ex() that, at least, lets you specify an | |
22 | * appropriate 'block' size that will be honoured by bn_expand_internal() to | |
23 | * prevent piddly little reallocations. OTOH, profiling bignum expansions in | |
24 | * BN_CTX doesn't show this to be a big issue. | |
25 | */ | |
26 | ||
27 | /* How many bignums are in each "pool item"; */ | |
0f113f3e | 28 | #define BN_CTX_POOL_SIZE 16 |
5c98b2ca | 29 | /* The stack frame info is resizing, set a first-time expansion size; */ |
0f113f3e | 30 | #define BN_CTX_START_FRAMES 32 |
5c98b2ca GT |
31 | |
32 | /***********/ | |
33 | /* BN_POOL */ | |
34 | /***********/ | |
35 | ||
36 | /* A bundle of bignums that can be linked with other bundles */ | |
0f113f3e MC |
37 | typedef struct bignum_pool_item { |
38 | /* The bignum values */ | |
39 | BIGNUM vals[BN_CTX_POOL_SIZE]; | |
40 | /* Linked-list admin */ | |
41 | struct bignum_pool_item *prev, *next; | |
42 | } BN_POOL_ITEM; | |
5c98b2ca | 43 | /* A linked-list of bignums grouped in bundles */ |
0f113f3e MC |
44 | typedef struct bignum_pool { |
45 | /* Linked-list admin */ | |
46 | BN_POOL_ITEM *head, *current, *tail; | |
47 | /* Stack depth and allocation size */ | |
48 | unsigned used, size; | |
49 | } BN_POOL; | |
50 | static void BN_POOL_init(BN_POOL *); | |
51 | static void BN_POOL_finish(BN_POOL *); | |
74924dcb | 52 | static BIGNUM *BN_POOL_get(BN_POOL *, int); |
0f113f3e | 53 | static void BN_POOL_release(BN_POOL *, unsigned int); |
5c98b2ca GT |
54 | |
55 | /************/ | |
56 | /* BN_STACK */ | |
57 | /************/ | |
58 | ||
59 | /* A wrapper to manage the "stack frames" */ | |
0f113f3e MC |
60 | typedef struct bignum_ctx_stack { |
61 | /* Array of indexes into the bignum stack */ | |
62 | unsigned int *indexes; | |
63 | /* Number of stack frames, and the size of the allocated array */ | |
64 | unsigned int depth, size; | |
65 | } BN_STACK; | |
66 | static void BN_STACK_init(BN_STACK *); | |
67 | static void BN_STACK_finish(BN_STACK *); | |
0f113f3e MC |
68 | static int BN_STACK_push(BN_STACK *, unsigned int); |
69 | static unsigned int BN_STACK_pop(BN_STACK *); | |
5c98b2ca GT |
70 | |
71 | /**********/ | |
72 | /* BN_CTX */ | |
73 | /**********/ | |
74 | ||
75 | /* The opaque BN_CTX type */ | |
0f113f3e MC |
76 | struct bignum_ctx { |
77 | /* The bignum bundles */ | |
78 | BN_POOL pool; | |
79 | /* The "stack frames", if you will */ | |
80 | BN_STACK stack; | |
81 | /* The number of bignums currently assigned */ | |
82 | unsigned int used; | |
83 | /* Depth of stack overflow */ | |
84 | int err_stack; | |
85 | /* Block "gets" until an "end" (compatibility behaviour) */ | |
86 | int too_many; | |
74924dcb RS |
87 | /* Flags. */ |
88 | int flags; | |
7bc081dd MC |
89 | /* The library context */ |
90 | OPENSSL_CTX *libctx; | |
0f113f3e | 91 | }; |
9b141126 | 92 | |
636b087e | 93 | #ifndef FIPS_MODE |
6e810f2d RL |
94 | /* Debugging functionality */ |
95 | static void ctxdbg(BIO *channel, const char *text, BN_CTX *ctx) | |
0f113f3e MC |
96 | { |
97 | unsigned int bnidx = 0, fpidx = 0; | |
98 | BN_POOL_ITEM *item = ctx->pool.head; | |
99 | BN_STACK *stack = &ctx->stack; | |
6e810f2d RL |
100 | |
101 | BIO_printf(channel, "%s\n", text); | |
102 | BIO_printf(channel, " (%16p): ", (void*)ctx); | |
0f113f3e | 103 | while (bnidx < ctx->used) { |
6e810f2d RL |
104 | BIO_printf(channel, "%03x ", |
105 | item->vals[bnidx++ % BN_CTX_POOL_SIZE].dmax); | |
0f113f3e MC |
106 | if (!(bnidx % BN_CTX_POOL_SIZE)) |
107 | item = item->next; | |
108 | } | |
6e810f2d | 109 | BIO_printf(channel, "\n"); |
0f113f3e | 110 | bnidx = 0; |
6e810f2d | 111 | BIO_printf(channel, " %16s : ", ""); |
0f113f3e MC |
112 | while (fpidx < stack->depth) { |
113 | while (bnidx++ < stack->indexes[fpidx]) | |
6e810f2d RL |
114 | BIO_printf(channel, " "); |
115 | BIO_printf(channel, "^^^ "); | |
0f113f3e MC |
116 | bnidx++; |
117 | fpidx++; | |
118 | } | |
6e810f2d | 119 | BIO_printf(channel, "\n"); |
0f113f3e MC |
120 | } |
121 | ||
636b087e | 122 | # define CTXDBG(str, ctx) \ |
6e810f2d RL |
123 | OSSL_TRACE_BEGIN(BN_CTX) { \ |
124 | ctxdbg(trc_out, str, ctx); \ | |
125 | } OSSL_TRACE_END(BN_CTX) | |
636b087e MC |
126 | #else |
127 | /* TODO(3.0): Consider if we want to do this in FIPS mode */ | |
128 | # define CTXDBG(str, ctx) do {} while(0) | |
129 | #endif /* FIPS_MODE */ | |
5c98b2ca | 130 | |
7bc081dd | 131 | BN_CTX *BN_CTX_new_ex(OPENSSL_CTX *ctx) |
0f113f3e | 132 | { |
74924dcb RS |
133 | BN_CTX *ret; |
134 | ||
64b25758 | 135 | if ((ret = OPENSSL_zalloc(sizeof(*ret))) == NULL) { |
7bc081dd | 136 | BNerr(BN_F_BN_CTX_NEW_EX, ERR_R_MALLOC_FAILURE); |
0f113f3e MC |
137 | return NULL; |
138 | } | |
139 | /* Initialise the structure */ | |
140 | BN_POOL_init(&ret->pool); | |
141 | BN_STACK_init(&ret->stack); | |
7bc081dd | 142 | ret->libctx = ctx; |
74924dcb RS |
143 | return ret; |
144 | } | |
145 | ||
7bc081dd | 146 | BN_CTX *BN_CTX_new(void) |
74924dcb | 147 | { |
7bc081dd MC |
148 | return BN_CTX_new_ex(NULL); |
149 | } | |
150 | ||
151 | BN_CTX *BN_CTX_secure_new_ex(OPENSSL_CTX *ctx) | |
152 | { | |
153 | BN_CTX *ret = BN_CTX_new_ex(ctx); | |
74924dcb | 154 | |
90945fa3 | 155 | if (ret != NULL) |
74924dcb | 156 | ret->flags = BN_FLG_SECURE; |
0f113f3e MC |
157 | return ret; |
158 | } | |
2ce90b9b | 159 | |
7bc081dd MC |
160 | BN_CTX *BN_CTX_secure_new(void) |
161 | { | |
162 | return BN_CTX_secure_new_ex(NULL); | |
163 | } | |
164 | ||
9b141126 | 165 | void BN_CTX_free(BN_CTX *ctx) |
0f113f3e | 166 | { |
e6e9170d RS |
167 | if (ctx == NULL) |
168 | return; | |
6e810f2d | 169 | OSSL_TRACE_BEGIN(BN_CTX) { |
0f113f3e | 170 | BN_POOL_ITEM *pool = ctx->pool.head; |
6e810f2d RL |
171 | BIO_printf(trc_out, |
172 | "BN_CTX_free(): stack-size=%d, pool-bignums=%d\n", | |
173 | ctx->stack.size, ctx->pool.size); | |
174 | BIO_printf(trc_out, " dmaxs: "); | |
0f113f3e MC |
175 | while (pool) { |
176 | unsigned loop = 0; | |
177 | while (loop < BN_CTX_POOL_SIZE) | |
6e810f2d | 178 | BIO_printf(trc_out, "%02x ", pool->vals[loop++].dmax); |
0f113f3e MC |
179 | pool = pool->next; |
180 | } | |
6e810f2d RL |
181 | BIO_printf(trc_out, "\n"); |
182 | } OSSL_TRACE_END(BN_CTX); | |
0f113f3e MC |
183 | BN_STACK_finish(&ctx->stack); |
184 | BN_POOL_finish(&ctx->pool); | |
185 | OPENSSL_free(ctx); | |
186 | } | |
9b141126 UM |
187 | |
188 | void BN_CTX_start(BN_CTX *ctx) | |
0f113f3e | 189 | { |
6e810f2d | 190 | CTXDBG("ENTER BN_CTX_start()", ctx); |
0f113f3e MC |
191 | /* If we're already overflowing ... */ |
192 | if (ctx->err_stack || ctx->too_many) | |
193 | ctx->err_stack++; | |
194 | /* (Try to) get a new frame pointer */ | |
195 | else if (!BN_STACK_push(&ctx->stack, ctx->used)) { | |
196 | BNerr(BN_F_BN_CTX_START, BN_R_TOO_MANY_TEMPORARY_VARIABLES); | |
197 | ctx->err_stack++; | |
198 | } | |
6e810f2d | 199 | CTXDBG("LEAVE BN_CTX_start()", ctx); |
0f113f3e | 200 | } |
9b141126 | 201 | |
5c98b2ca | 202 | void BN_CTX_end(BN_CTX *ctx) |
0f113f3e | 203 | { |
ce1415ed SL |
204 | if (ctx == NULL) |
205 | return; | |
6e810f2d | 206 | CTXDBG("ENTER BN_CTX_end()", ctx); |
0f113f3e MC |
207 | if (ctx->err_stack) |
208 | ctx->err_stack--; | |
209 | else { | |
210 | unsigned int fp = BN_STACK_pop(&ctx->stack); | |
211 | /* Does this stack frame have anything to release? */ | |
212 | if (fp < ctx->used) | |
213 | BN_POOL_release(&ctx->pool, ctx->used - fp); | |
214 | ctx->used = fp; | |
215 | /* Unjam "too_many" in case "get" had failed */ | |
216 | ctx->too_many = 0; | |
217 | } | |
6e810f2d | 218 | CTXDBG("LEAVE BN_CTX_end()", ctx); |
0f113f3e | 219 | } |
7f7b8d68 | 220 | |
9b141126 | 221 | BIGNUM *BN_CTX_get(BN_CTX *ctx) |
0f113f3e MC |
222 | { |
223 | BIGNUM *ret; | |
74924dcb | 224 | |
6e810f2d | 225 | CTXDBG("ENTER BN_CTX_get()", ctx); |
0f113f3e MC |
226 | if (ctx->err_stack || ctx->too_many) |
227 | return NULL; | |
74924dcb | 228 | if ((ret = BN_POOL_get(&ctx->pool, ctx->flags)) == NULL) { |
0f113f3e MC |
229 | /* |
230 | * Setting too_many prevents repeated "get" attempts from cluttering | |
231 | * the error stack. | |
232 | */ | |
233 | ctx->too_many = 1; | |
234 | BNerr(BN_F_BN_CTX_GET, BN_R_TOO_MANY_TEMPORARY_VARIABLES); | |
235 | return NULL; | |
236 | } | |
237 | /* OK, make sure the returned bignum is "zero" */ | |
238 | BN_zero(ret); | |
c8147d37 NT |
239 | /* clear BN_FLG_CONSTTIME if leaked from previous frames */ |
240 | ret->flags &= (~BN_FLG_CONSTTIME); | |
0f113f3e | 241 | ctx->used++; |
6e810f2d | 242 | CTXDBG("LEAVE BN_CTX_get()", ctx); |
0f113f3e MC |
243 | return ret; |
244 | } | |
9b141126 | 245 | |
636b087e MC |
246 | OPENSSL_CTX *bn_get_lib_ctx(BN_CTX *ctx) |
247 | { | |
248 | return ctx->libctx; | |
249 | } | |
250 | ||
5c98b2ca GT |
251 | /************/ |
252 | /* BN_STACK */ | |
253 | /************/ | |
254 | ||
255 | static void BN_STACK_init(BN_STACK *st) | |
0f113f3e MC |
256 | { |
257 | st->indexes = NULL; | |
258 | st->depth = st->size = 0; | |
259 | } | |
5c98b2ca GT |
260 | |
261 | static void BN_STACK_finish(BN_STACK *st) | |
0f113f3e | 262 | { |
74924dcb RS |
263 | OPENSSL_free(st->indexes); |
264 | st->indexes = NULL; | |
0f113f3e | 265 | } |
37e48b88 | 266 | |
5c98b2ca GT |
267 | |
268 | static int BN_STACK_push(BN_STACK *st, unsigned int idx) | |
0f113f3e | 269 | { |
74924dcb | 270 | if (st->depth == st->size) { |
0f113f3e | 271 | /* Need to expand */ |
74924dcb RS |
272 | unsigned int newsize = |
273 | st->size ? (st->size * 3 / 2) : BN_CTX_START_FRAMES; | |
cdb10bae | 274 | unsigned int *newitems; |
df443918 | 275 | |
cdb10bae RS |
276 | if ((newitems = OPENSSL_malloc(sizeof(*newitems) * newsize)) == NULL) { |
277 | BNerr(BN_F_BN_STACK_PUSH, ERR_R_MALLOC_FAILURE); | |
0f113f3e | 278 | return 0; |
cdb10bae | 279 | } |
0f113f3e | 280 | if (st->depth) |
74924dcb RS |
281 | memcpy(newitems, st->indexes, sizeof(*newitems) * st->depth); |
282 | OPENSSL_free(st->indexes); | |
0f113f3e MC |
283 | st->indexes = newitems; |
284 | st->size = newsize; | |
285 | } | |
286 | st->indexes[(st->depth)++] = idx; | |
287 | return 1; | |
288 | } | |
5c98b2ca GT |
289 | |
290 | static unsigned int BN_STACK_pop(BN_STACK *st) | |
0f113f3e MC |
291 | { |
292 | return st->indexes[--(st->depth)]; | |
293 | } | |
5c98b2ca GT |
294 | |
295 | /***********/ | |
296 | /* BN_POOL */ | |
297 | /***********/ | |
298 | ||
299 | static void BN_POOL_init(BN_POOL *p) | |
0f113f3e MC |
300 | { |
301 | p->head = p->current = p->tail = NULL; | |
302 | p->used = p->size = 0; | |
303 | } | |
5c98b2ca GT |
304 | |
305 | static void BN_POOL_finish(BN_POOL *p) | |
0f113f3e | 306 | { |
74924dcb RS |
307 | unsigned int loop; |
308 | BIGNUM *bn; | |
309 | ||
0f113f3e | 310 | while (p->head) { |
74924dcb | 311 | for (loop = 0, bn = p->head->vals; loop++ < BN_CTX_POOL_SIZE; bn++) |
0f113f3e MC |
312 | if (bn->d) |
313 | BN_clear_free(bn); | |
0f113f3e MC |
314 | p->current = p->head->next; |
315 | OPENSSL_free(p->head); | |
316 | p->head = p->current; | |
317 | } | |
318 | } | |
5c98b2ca | 319 | |
5c98b2ca | 320 | |
74924dcb | 321 | static BIGNUM *BN_POOL_get(BN_POOL *p, int flag) |
0f113f3e | 322 | { |
74924dcb RS |
323 | BIGNUM *bn; |
324 | unsigned int loop; | |
325 | ||
326 | /* Full; allocate a new pool item and link it in. */ | |
0f113f3e | 327 | if (p->used == p->size) { |
cdb10bae | 328 | BN_POOL_ITEM *item; |
df443918 | 329 | |
cdb10bae RS |
330 | if ((item = OPENSSL_malloc(sizeof(*item))) == NULL) { |
331 | BNerr(BN_F_BN_POOL_GET, ERR_R_MALLOC_FAILURE); | |
0f113f3e | 332 | return NULL; |
cdb10bae | 333 | } |
74924dcb | 334 | for (loop = 0, bn = item->vals; loop++ < BN_CTX_POOL_SIZE; bn++) { |
d59c7c81 | 335 | bn_init(bn); |
74924dcb RS |
336 | if ((flag & BN_FLG_SECURE) != 0) |
337 | BN_set_flags(bn, BN_FLG_SECURE); | |
338 | } | |
0f113f3e MC |
339 | item->prev = p->tail; |
340 | item->next = NULL; | |
74924dcb RS |
341 | |
342 | if (p->head == NULL) | |
0f113f3e MC |
343 | p->head = p->current = p->tail = item; |
344 | else { | |
345 | p->tail->next = item; | |
346 | p->tail = item; | |
347 | p->current = item; | |
348 | } | |
349 | p->size += BN_CTX_POOL_SIZE; | |
350 | p->used++; | |
351 | /* Return the first bignum from the new pool */ | |
352 | return item->vals; | |
353 | } | |
74924dcb | 354 | |
0f113f3e MC |
355 | if (!p->used) |
356 | p->current = p->head; | |
357 | else if ((p->used % BN_CTX_POOL_SIZE) == 0) | |
358 | p->current = p->current->next; | |
359 | return p->current->vals + ((p->used++) % BN_CTX_POOL_SIZE); | |
360 | } | |
5c98b2ca GT |
361 | |
362 | static void BN_POOL_release(BN_POOL *p, unsigned int num) | |
0f113f3e MC |
363 | { |
364 | unsigned int offset = (p->used - 1) % BN_CTX_POOL_SIZE; | |
74924dcb | 365 | |
0f113f3e MC |
366 | p->used -= num; |
367 | while (num--) { | |
368 | bn_check_top(p->current->vals + offset); | |
74924dcb | 369 | if (offset == 0) { |
0f113f3e MC |
370 | offset = BN_CTX_POOL_SIZE - 1; |
371 | p->current = p->current->prev; | |
372 | } else | |
373 | offset--; | |
374 | } | |
375 | } |