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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; | |
0f113f3e | 89 | }; |
9b141126 | 90 | |
6e810f2d RL |
91 | /* Debugging functionality */ |
92 | static void ctxdbg(BIO *channel, const char *text, BN_CTX *ctx) | |
0f113f3e MC |
93 | { |
94 | unsigned int bnidx = 0, fpidx = 0; | |
95 | BN_POOL_ITEM *item = ctx->pool.head; | |
96 | BN_STACK *stack = &ctx->stack; | |
6e810f2d RL |
97 | |
98 | BIO_printf(channel, "%s\n", text); | |
99 | BIO_printf(channel, " (%16p): ", (void*)ctx); | |
0f113f3e | 100 | while (bnidx < ctx->used) { |
6e810f2d RL |
101 | BIO_printf(channel, "%03x ", |
102 | item->vals[bnidx++ % BN_CTX_POOL_SIZE].dmax); | |
0f113f3e MC |
103 | if (!(bnidx % BN_CTX_POOL_SIZE)) |
104 | item = item->next; | |
105 | } | |
6e810f2d | 106 | BIO_printf(channel, "\n"); |
0f113f3e | 107 | bnidx = 0; |
6e810f2d | 108 | BIO_printf(channel, " %16s : ", ""); |
0f113f3e MC |
109 | while (fpidx < stack->depth) { |
110 | while (bnidx++ < stack->indexes[fpidx]) | |
6e810f2d RL |
111 | BIO_printf(channel, " "); |
112 | BIO_printf(channel, "^^^ "); | |
0f113f3e MC |
113 | bnidx++; |
114 | fpidx++; | |
115 | } | |
6e810f2d | 116 | BIO_printf(channel, "\n"); |
0f113f3e MC |
117 | } |
118 | ||
6e810f2d RL |
119 | #define CTXDBG(str, ctx) \ |
120 | OSSL_TRACE_BEGIN(BN_CTX) { \ | |
121 | ctxdbg(trc_out, str, ctx); \ | |
122 | } OSSL_TRACE_END(BN_CTX) | |
5c98b2ca | 123 | |
9b141126 | 124 | |
2ce90b9b | 125 | BN_CTX *BN_CTX_new(void) |
0f113f3e | 126 | { |
74924dcb RS |
127 | BN_CTX *ret; |
128 | ||
64b25758 | 129 | if ((ret = OPENSSL_zalloc(sizeof(*ret))) == NULL) { |
0f113f3e MC |
130 | BNerr(BN_F_BN_CTX_NEW, ERR_R_MALLOC_FAILURE); |
131 | return NULL; | |
132 | } | |
133 | /* Initialise the structure */ | |
134 | BN_POOL_init(&ret->pool); | |
135 | BN_STACK_init(&ret->stack); | |
74924dcb RS |
136 | return ret; |
137 | } | |
138 | ||
139 | BN_CTX *BN_CTX_secure_new(void) | |
140 | { | |
141 | BN_CTX *ret = BN_CTX_new(); | |
142 | ||
90945fa3 | 143 | if (ret != NULL) |
74924dcb | 144 | ret->flags = BN_FLG_SECURE; |
0f113f3e MC |
145 | return ret; |
146 | } | |
2ce90b9b | 147 | |
9b141126 | 148 | void BN_CTX_free(BN_CTX *ctx) |
0f113f3e | 149 | { |
e6e9170d RS |
150 | if (ctx == NULL) |
151 | return; | |
6e810f2d | 152 | OSSL_TRACE_BEGIN(BN_CTX) { |
0f113f3e | 153 | BN_POOL_ITEM *pool = ctx->pool.head; |
6e810f2d RL |
154 | BIO_printf(trc_out, |
155 | "BN_CTX_free(): stack-size=%d, pool-bignums=%d\n", | |
156 | ctx->stack.size, ctx->pool.size); | |
157 | BIO_printf(trc_out, " dmaxs: "); | |
0f113f3e MC |
158 | while (pool) { |
159 | unsigned loop = 0; | |
160 | while (loop < BN_CTX_POOL_SIZE) | |
6e810f2d | 161 | BIO_printf(trc_out, "%02x ", pool->vals[loop++].dmax); |
0f113f3e MC |
162 | pool = pool->next; |
163 | } | |
6e810f2d RL |
164 | BIO_printf(trc_out, "\n"); |
165 | } OSSL_TRACE_END(BN_CTX); | |
0f113f3e MC |
166 | BN_STACK_finish(&ctx->stack); |
167 | BN_POOL_finish(&ctx->pool); | |
168 | OPENSSL_free(ctx); | |
169 | } | |
9b141126 UM |
170 | |
171 | void BN_CTX_start(BN_CTX *ctx) | |
0f113f3e | 172 | { |
6e810f2d | 173 | CTXDBG("ENTER BN_CTX_start()", ctx); |
0f113f3e MC |
174 | /* If we're already overflowing ... */ |
175 | if (ctx->err_stack || ctx->too_many) | |
176 | ctx->err_stack++; | |
177 | /* (Try to) get a new frame pointer */ | |
178 | else if (!BN_STACK_push(&ctx->stack, ctx->used)) { | |
179 | BNerr(BN_F_BN_CTX_START, BN_R_TOO_MANY_TEMPORARY_VARIABLES); | |
180 | ctx->err_stack++; | |
181 | } | |
6e810f2d | 182 | CTXDBG("LEAVE BN_CTX_start()", ctx); |
0f113f3e | 183 | } |
9b141126 | 184 | |
5c98b2ca | 185 | void BN_CTX_end(BN_CTX *ctx) |
0f113f3e | 186 | { |
6e810f2d | 187 | CTXDBG("ENTER BN_CTX_end()", ctx); |
0f113f3e MC |
188 | if (ctx->err_stack) |
189 | ctx->err_stack--; | |
190 | else { | |
191 | unsigned int fp = BN_STACK_pop(&ctx->stack); | |
192 | /* Does this stack frame have anything to release? */ | |
193 | if (fp < ctx->used) | |
194 | BN_POOL_release(&ctx->pool, ctx->used - fp); | |
195 | ctx->used = fp; | |
196 | /* Unjam "too_many" in case "get" had failed */ | |
197 | ctx->too_many = 0; | |
198 | } | |
6e810f2d | 199 | CTXDBG("LEAVE BN_CTX_end()", ctx); |
0f113f3e | 200 | } |
7f7b8d68 | 201 | |
9b141126 | 202 | BIGNUM *BN_CTX_get(BN_CTX *ctx) |
0f113f3e MC |
203 | { |
204 | BIGNUM *ret; | |
74924dcb | 205 | |
6e810f2d | 206 | CTXDBG("ENTER BN_CTX_get()", ctx); |
0f113f3e MC |
207 | if (ctx->err_stack || ctx->too_many) |
208 | return NULL; | |
74924dcb | 209 | if ((ret = BN_POOL_get(&ctx->pool, ctx->flags)) == NULL) { |
0f113f3e MC |
210 | /* |
211 | * Setting too_many prevents repeated "get" attempts from cluttering | |
212 | * the error stack. | |
213 | */ | |
214 | ctx->too_many = 1; | |
215 | BNerr(BN_F_BN_CTX_GET, BN_R_TOO_MANY_TEMPORARY_VARIABLES); | |
216 | return NULL; | |
217 | } | |
218 | /* OK, make sure the returned bignum is "zero" */ | |
219 | BN_zero(ret); | |
c8147d37 NT |
220 | /* clear BN_FLG_CONSTTIME if leaked from previous frames */ |
221 | ret->flags &= (~BN_FLG_CONSTTIME); | |
0f113f3e | 222 | ctx->used++; |
6e810f2d | 223 | CTXDBG("LEAVE BN_CTX_get()", ctx); |
0f113f3e MC |
224 | return ret; |
225 | } | |
9b141126 | 226 | |
5c98b2ca GT |
227 | /************/ |
228 | /* BN_STACK */ | |
229 | /************/ | |
230 | ||
231 | static void BN_STACK_init(BN_STACK *st) | |
0f113f3e MC |
232 | { |
233 | st->indexes = NULL; | |
234 | st->depth = st->size = 0; | |
235 | } | |
5c98b2ca GT |
236 | |
237 | static void BN_STACK_finish(BN_STACK *st) | |
0f113f3e | 238 | { |
74924dcb RS |
239 | OPENSSL_free(st->indexes); |
240 | st->indexes = NULL; | |
0f113f3e | 241 | } |
37e48b88 | 242 | |
5c98b2ca GT |
243 | |
244 | static int BN_STACK_push(BN_STACK *st, unsigned int idx) | |
0f113f3e | 245 | { |
74924dcb | 246 | if (st->depth == st->size) { |
0f113f3e | 247 | /* Need to expand */ |
74924dcb RS |
248 | unsigned int newsize = |
249 | st->size ? (st->size * 3 / 2) : BN_CTX_START_FRAMES; | |
cdb10bae | 250 | unsigned int *newitems; |
df443918 | 251 | |
cdb10bae RS |
252 | if ((newitems = OPENSSL_malloc(sizeof(*newitems) * newsize)) == NULL) { |
253 | BNerr(BN_F_BN_STACK_PUSH, ERR_R_MALLOC_FAILURE); | |
0f113f3e | 254 | return 0; |
cdb10bae | 255 | } |
0f113f3e | 256 | if (st->depth) |
74924dcb RS |
257 | memcpy(newitems, st->indexes, sizeof(*newitems) * st->depth); |
258 | OPENSSL_free(st->indexes); | |
0f113f3e MC |
259 | st->indexes = newitems; |
260 | st->size = newsize; | |
261 | } | |
262 | st->indexes[(st->depth)++] = idx; | |
263 | return 1; | |
264 | } | |
5c98b2ca GT |
265 | |
266 | static unsigned int BN_STACK_pop(BN_STACK *st) | |
0f113f3e MC |
267 | { |
268 | return st->indexes[--(st->depth)]; | |
269 | } | |
5c98b2ca GT |
270 | |
271 | /***********/ | |
272 | /* BN_POOL */ | |
273 | /***********/ | |
274 | ||
275 | static void BN_POOL_init(BN_POOL *p) | |
0f113f3e MC |
276 | { |
277 | p->head = p->current = p->tail = NULL; | |
278 | p->used = p->size = 0; | |
279 | } | |
5c98b2ca GT |
280 | |
281 | static void BN_POOL_finish(BN_POOL *p) | |
0f113f3e | 282 | { |
74924dcb RS |
283 | unsigned int loop; |
284 | BIGNUM *bn; | |
285 | ||
0f113f3e | 286 | while (p->head) { |
74924dcb | 287 | for (loop = 0, bn = p->head->vals; loop++ < BN_CTX_POOL_SIZE; bn++) |
0f113f3e MC |
288 | if (bn->d) |
289 | BN_clear_free(bn); | |
0f113f3e MC |
290 | p->current = p->head->next; |
291 | OPENSSL_free(p->head); | |
292 | p->head = p->current; | |
293 | } | |
294 | } | |
5c98b2ca | 295 | |
5c98b2ca | 296 | |
74924dcb | 297 | static BIGNUM *BN_POOL_get(BN_POOL *p, int flag) |
0f113f3e | 298 | { |
74924dcb RS |
299 | BIGNUM *bn; |
300 | unsigned int loop; | |
301 | ||
302 | /* Full; allocate a new pool item and link it in. */ | |
0f113f3e | 303 | if (p->used == p->size) { |
cdb10bae | 304 | BN_POOL_ITEM *item; |
df443918 | 305 | |
cdb10bae RS |
306 | if ((item = OPENSSL_malloc(sizeof(*item))) == NULL) { |
307 | BNerr(BN_F_BN_POOL_GET, ERR_R_MALLOC_FAILURE); | |
0f113f3e | 308 | return NULL; |
cdb10bae | 309 | } |
74924dcb | 310 | for (loop = 0, bn = item->vals; loop++ < BN_CTX_POOL_SIZE; bn++) { |
d59c7c81 | 311 | bn_init(bn); |
74924dcb RS |
312 | if ((flag & BN_FLG_SECURE) != 0) |
313 | BN_set_flags(bn, BN_FLG_SECURE); | |
314 | } | |
0f113f3e MC |
315 | item->prev = p->tail; |
316 | item->next = NULL; | |
74924dcb RS |
317 | |
318 | if (p->head == NULL) | |
0f113f3e MC |
319 | p->head = p->current = p->tail = item; |
320 | else { | |
321 | p->tail->next = item; | |
322 | p->tail = item; | |
323 | p->current = item; | |
324 | } | |
325 | p->size += BN_CTX_POOL_SIZE; | |
326 | p->used++; | |
327 | /* Return the first bignum from the new pool */ | |
328 | return item->vals; | |
329 | } | |
74924dcb | 330 | |
0f113f3e MC |
331 | if (!p->used) |
332 | p->current = p->head; | |
333 | else if ((p->used % BN_CTX_POOL_SIZE) == 0) | |
334 | p->current = p->current->next; | |
335 | return p->current->vals + ((p->used++) % BN_CTX_POOL_SIZE); | |
336 | } | |
5c98b2ca GT |
337 | |
338 | static void BN_POOL_release(BN_POOL *p, unsigned int num) | |
0f113f3e MC |
339 | { |
340 | unsigned int offset = (p->used - 1) % BN_CTX_POOL_SIZE; | |
74924dcb | 341 | |
0f113f3e MC |
342 | p->used -= num; |
343 | while (num--) { | |
344 | bn_check_top(p->current->vals + offset); | |
74924dcb | 345 | if (offset == 0) { |
0f113f3e MC |
346 | offset = BN_CTX_POOL_SIZE - 1; |
347 | p->current = p->current->prev; | |
348 | } else | |
349 | offset--; | |
350 | } | |
351 | } |