Bug Summary

File:out/../deps/openssl/openssl/crypto/bn/bn_exp.c
Warning:line 378, column 5
Value stored to 'wend' is never read

Annotated Source Code

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clang -cc1 -cc1 -triple x86_64-unknown-linux-gnu -analyze -disable-free -clear-ast-before-backend -disable-llvm-verifier -discard-value-names -main-file-name bn_exp.c -analyzer-checker=core -analyzer-checker=apiModeling -analyzer-checker=unix -analyzer-checker=deadcode -analyzer-checker=security.insecureAPI.UncheckedReturn -analyzer-checker=security.insecureAPI.getpw -analyzer-checker=security.insecureAPI.gets -analyzer-checker=security.insecureAPI.mktemp -analyzer-checker=security.insecureAPI.mkstemp -analyzer-checker=security.insecureAPI.vfork -analyzer-checker=nullability.NullPassedToNonnull -analyzer-checker=nullability.NullReturnedFromNonnull -analyzer-output plist -w -setup-static-analyzer -mrelocation-model pic -pic-level 2 -pic-is-pie -mframe-pointer=all -fmath-errno -ffp-contract=on -fno-rounding-math -mconstructor-aliases -funwind-tables=2 -target-cpu x86-64 -tune-cpu generic -debugger-tuning=gdb -fcoverage-compilation-dir=/home/maurizio/node-v18.6.0/out -resource-dir /usr/local/lib/clang/16.0.0 -D V8_DEPRECATION_WARNINGS -D V8_IMMINENT_DEPRECATION_WARNINGS -D _GLIBCXX_USE_CXX11_ABI=1 -D NODE_OPENSSL_CONF_NAME=nodejs_conf -D NODE_OPENSSL_HAS_QUIC -D __STDC_FORMAT_MACROS -D OPENSSL_NO_PINSHARED -D OPENSSL_THREADS -D OPENSSL_NO_HW -D OPENSSL_API_COMPAT=0x10100001L -D STATIC_LEGACY -D NDEBUG -D OPENSSL_USE_NODELETE -D L_ENDIAN -D OPENSSL_BUILDING_OPENSSL -D AES_ASM -D BSAES_ASM -D CMLL_ASM -D ECP_NISTZ256_ASM -D GHASH_ASM -D KECCAK1600_ASM -D MD5_ASM -D OPENSSL_BN_ASM_GF2m -D OPENSSL_BN_ASM_MONT -D OPENSSL_BN_ASM_MONT5 -D OPENSSL_CPUID_OBJ -D OPENSSL_IA32_SSE2 -D PADLOCK_ASM -D POLY1305_ASM -D SHA1_ASM -D SHA256_ASM -D SHA512_ASM -D VPAES_ASM -D WHIRLPOOL_ASM -D X25519_ASM -D OPENSSL_PIC -D MODULESDIR="/home/maurizio/node-v18.6.0/out/Release/obj.target/deps/openssl/lib/openssl-modules" -D OPENSSLDIR="/home/maurizio/node-v18.6.0/out/Release/obj.target/deps/openssl" -D OPENSSLDIR="/etc/ssl" -D ENGINESDIR="/dev/null" -D TERMIOS -I ../deps/openssl/openssl -I ../deps/openssl/openssl/include -I ../deps/openssl/openssl/crypto -I ../deps/openssl/openssl/crypto/include -I ../deps/openssl/openssl/crypto/modes -I ../deps/openssl/openssl/crypto/ec/curve448 -I ../deps/openssl/openssl/crypto/ec/curve448/arch_32 -I ../deps/openssl/openssl/providers/common/include -I ../deps/openssl/openssl/providers/implementations/include -I ../deps/openssl/config -I ../deps/openssl/config/archs/linux-x86_64/asm -I ../deps/openssl/config/archs/linux-x86_64/asm/include -I ../deps/openssl/config/archs/linux-x86_64/asm/crypto -I ../deps/openssl/config/archs/linux-x86_64/asm/crypto/include/internal -I ../deps/openssl/config/archs/linux-x86_64/asm/providers/common/include -internal-isystem /usr/local/lib/clang/16.0.0/include -internal-isystem /usr/local/include -internal-isystem /usr/lib/gcc/x86_64-redhat-linux/8/../../../../x86_64-redhat-linux/include -internal-externc-isystem /include -internal-externc-isystem /usr/include -O3 -Wno-unused-parameter -Wno-missing-field-initializers -Wno-old-style-declaration -fdebug-compilation-dir=/home/maurizio/node-v18.6.0/out -ferror-limit 19 -fgnuc-version=4.2.1 -vectorize-loops -vectorize-slp -analyzer-output=html -faddrsig -D__GCC_HAVE_DWARF2_CFI_ASM=1 -o /tmp/scan-build-2022-08-22-142216-507842-1 -x c ../deps/openssl/openssl/crypto/bn/bn_exp.c
1/*
2 * Copyright 1995-2022 The OpenSSL Project Authors. All Rights Reserved.
3 *
4 * Licensed under the Apache License 2.0 (the "License"). You may not use
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
8 */
9
10#include "internal/cryptlib.h"
11#include "internal/constant_time.h"
12#include "bn_local.h"
13
14#include <stdlib.h>
15#ifdef _WIN32
16# include <malloc.h>
17# ifndef alloca
18# define alloca _alloca
19# endif
20#elif defined(__GNUC__4)
21# ifndef alloca
22# define alloca(s)__builtin_alloca (s) __builtin_alloca((s))
23# endif
24#elif defined(__sun)
25# include <alloca.h>
26#endif
27
28#include "rsaz_exp.h"
29
30#undef SPARC_T4_MONT
31#if defined(OPENSSL_BN_ASM_MONT1) && (defined(__sparc__) || defined(__sparc))
32# include "crypto/sparc_arch.h"
33# define SPARC_T4_MONT
34#endif
35
36/* maximum precomputation table size for *variable* sliding windows */
37#define TABLE_SIZE32 32
38
39/* this one works - simple but works */
40int BN_exp(BIGNUM *r, const BIGNUM *a, const BIGNUM *p, BN_CTX *ctx)
41{
42 int i, bits, ret = 0;
43 BIGNUM *v, *rr;
44
45 if (BN_get_flags(p, BN_FLG_CONSTTIME0x04) != 0
46 || BN_get_flags(a, BN_FLG_CONSTTIME0x04) != 0) {
47 /* BN_FLG_CONSTTIME only supported by BN_mod_exp_mont() */
48 ERR_raise(ERR_LIB_BN, ERR_R_SHOULD_NOT_HAVE_BEEN_CALLED)(ERR_new(), ERR_set_debug("../deps/openssl/openssl/crypto/bn/bn_exp.c"
,48,__func__), ERR_set_error)((3),((257|((0x1 << 18L)|(
0x2 << 18L)))),((void*)0))
;
49 return 0;
50 }
51
52 BN_CTX_start(ctx);
53 rr = ((r == a) || (r == p)) ? BN_CTX_get(ctx) : r;
54 v = BN_CTX_get(ctx);
55 if (rr == NULL((void*)0) || v == NULL((void*)0))
56 goto err;
57
58 if (BN_copy(v, a) == NULL((void*)0))
59 goto err;
60 bits = BN_num_bits(p);
61
62 if (BN_is_odd(p)) {
63 if (BN_copy(rr, a) == NULL((void*)0))
64 goto err;
65 } else {
66 if (!BN_one(rr)(BN_set_word((rr),1)))
67 goto err;
68 }
69
70 for (i = 1; i < bits; i++) {
71 if (!BN_sqr(v, v, ctx))
72 goto err;
73 if (BN_is_bit_set(p, i)) {
74 if (!BN_mul(rr, rr, v, ctx))
75 goto err;
76 }
77 }
78 if (r != rr && BN_copy(r, rr) == NULL((void*)0))
79 goto err;
80
81 ret = 1;
82 err:
83 BN_CTX_end(ctx);
84 bn_check_top(r);
85 return ret;
86}
87
88int BN_mod_exp(BIGNUM *r, const BIGNUM *a, const BIGNUM *p, const BIGNUM *m,
89 BN_CTX *ctx)
90{
91 int ret;
92
93 bn_check_top(a);
94 bn_check_top(p);
95 bn_check_top(m);
96
97 /*-
98 * For even modulus m = 2^k*m_odd, it might make sense to compute
99 * a^p mod m_odd and a^p mod 2^k separately (with Montgomery
100 * exponentiation for the odd part), using appropriate exponent
101 * reductions, and combine the results using the CRT.
102 *
103 * For now, we use Montgomery only if the modulus is odd; otherwise,
104 * exponentiation using the reciprocal-based quick remaindering
105 * algorithm is used.
106 *
107 * (Timing obtained with expspeed.c [computations a^p mod m
108 * where a, p, m are of the same length: 256, 512, 1024, 2048,
109 * 4096, 8192 bits], compared to the running time of the
110 * standard algorithm:
111 *
112 * BN_mod_exp_mont 33 .. 40 % [AMD K6-2, Linux, debug configuration]
113 * 55 .. 77 % [UltraSparc processor, but
114 * debug-solaris-sparcv8-gcc conf.]
115 *
116 * BN_mod_exp_recp 50 .. 70 % [AMD K6-2, Linux, debug configuration]
117 * 62 .. 118 % [UltraSparc, debug-solaris-sparcv8-gcc]
118 *
119 * On the Sparc, BN_mod_exp_recp was faster than BN_mod_exp_mont
120 * at 2048 and more bits, but at 512 and 1024 bits, it was
121 * slower even than the standard algorithm!
122 *
123 * "Real" timings [linux-elf, solaris-sparcv9-gcc configurations]
124 * should be obtained when the new Montgomery reduction code
125 * has been integrated into OpenSSL.)
126 */
127
128#define MONT_MUL_MOD
129#define MONT_EXP_WORD
130#define RECP_MUL_MOD
131
132#ifdef MONT_MUL_MOD
133 if (BN_is_odd(m)) {
134# ifdef MONT_EXP_WORD
135 if (a->top == 1 && !a->neg
136 && (BN_get_flags(p, BN_FLG_CONSTTIME0x04) == 0)
137 && (BN_get_flags(a, BN_FLG_CONSTTIME0x04) == 0)
138 && (BN_get_flags(m, BN_FLG_CONSTTIME0x04) == 0)) {
139 BN_ULONGunsigned long A = a->d[0];
140 ret = BN_mod_exp_mont_word(r, A, p, m, ctx, NULL((void*)0));
141 } else
142# endif
143 ret = BN_mod_exp_mont(r, a, p, m, ctx, NULL((void*)0));
144 } else
145#endif
146#ifdef RECP_MUL_MOD
147 {
148 ret = BN_mod_exp_recp(r, a, p, m, ctx);
149 }
150#else
151 {
152 ret = BN_mod_exp_simple(r, a, p, m, ctx);
153 }
154#endif
155
156 bn_check_top(r);
157 return ret;
158}
159
160int BN_mod_exp_recp(BIGNUM *r, const BIGNUM *a, const BIGNUM *p,
161 const BIGNUM *m, BN_CTX *ctx)
162{
163 int i, j, bits, ret = 0, wstart, wend, window, wvalue;
164 int start = 1;
165 BIGNUM *aa;
166 /* Table of variables obtained from 'ctx' */
167 BIGNUM *val[TABLE_SIZE32];
168 BN_RECP_CTX recp;
169
170 if (BN_get_flags(p, BN_FLG_CONSTTIME0x04) != 0
171 || BN_get_flags(a, BN_FLG_CONSTTIME0x04) != 0
172 || BN_get_flags(m, BN_FLG_CONSTTIME0x04) != 0) {
173 /* BN_FLG_CONSTTIME only supported by BN_mod_exp_mont() */
174 ERR_raise(ERR_LIB_BN, ERR_R_SHOULD_NOT_HAVE_BEEN_CALLED)(ERR_new(), ERR_set_debug("../deps/openssl/openssl/crypto/bn/bn_exp.c"
,174,__func__), ERR_set_error)((3),((257|((0x1 << 18L)|
(0x2 << 18L)))),((void*)0))
;
175 return 0;
176 }
177
178 bits = BN_num_bits(p);
179 if (bits == 0) {
180 /* x**0 mod 1, or x**0 mod -1 is still zero. */
181 if (BN_abs_is_word(m, 1)) {
182 ret = 1;
183 BN_zero(r)BN_zero_ex(r);
184 } else {
185 ret = BN_one(r)(BN_set_word((r),1));
186 }
187 return ret;
188 }
189
190 BN_RECP_CTX_init(&recp);
191
192 BN_CTX_start(ctx);
193 aa = BN_CTX_get(ctx);
194 val[0] = BN_CTX_get(ctx);
195 if (val[0] == NULL((void*)0))
196 goto err;
197
198 if (m->neg) {
199 /* ignore sign of 'm' */
200 if (!BN_copy(aa, m))
201 goto err;
202 aa->neg = 0;
203 if (BN_RECP_CTX_set(&recp, aa, ctx) <= 0)
204 goto err;
205 } else {
206 if (BN_RECP_CTX_set(&recp, m, ctx) <= 0)
207 goto err;
208 }
209
210 if (!BN_nnmod(val[0], a, m, ctx))
211 goto err; /* 1 */
212 if (BN_is_zero(val[0])) {
213 BN_zero(r)BN_zero_ex(r);
214 ret = 1;
215 goto err;
216 }
217
218 window = BN_window_bits_for_exponent_size(bits)((bits) > 671 ? 6 : (bits) > 239 ? 5 : (bits) > 79 ?
4 : (bits) > 23 ? 3 : 1)
;
219 if (window > 1) {
220 if (!BN_mod_mul_reciprocal(aa, val[0], val[0], &recp, ctx))
221 goto err; /* 2 */
222 j = 1 << (window - 1);
223 for (i = 1; i < j; i++) {
224 if (((val[i] = BN_CTX_get(ctx)) == NULL((void*)0)) ||
225 !BN_mod_mul_reciprocal(val[i], val[i - 1], aa, &recp, ctx))
226 goto err;
227 }
228 }
229
230 start = 1; /* This is used to avoid multiplication etc
231 * when there is only the value '1' in the
232 * buffer. */
233 wvalue = 0; /* The 'value' of the window */
234 wstart = bits - 1; /* The top bit of the window */
235 wend = 0; /* The bottom bit of the window */
236
237 if (!BN_one(r)(BN_set_word((r),1)))
238 goto err;
239
240 for (;;) {
241 if (BN_is_bit_set(p, wstart) == 0) {
242 if (!start)
243 if (!BN_mod_mul_reciprocal(r, r, r, &recp, ctx))
244 goto err;
245 if (wstart == 0)
246 break;
247 wstart--;
248 continue;
249 }
250 /*
251 * We now have wstart on a 'set' bit, we now need to work out how bit
252 * a window to do. To do this we need to scan forward until the last
253 * set bit before the end of the window
254 */
255 wvalue = 1;
256 wend = 0;
257 for (i = 1; i < window; i++) {
258 if (wstart - i < 0)
259 break;
260 if (BN_is_bit_set(p, wstart - i)) {
261 wvalue <<= (i - wend);
262 wvalue |= 1;
263 wend = i;
264 }
265 }
266
267 /* wend is the size of the current window */
268 j = wend + 1;
269 /* add the 'bytes above' */
270 if (!start)
271 for (i = 0; i < j; i++) {
272 if (!BN_mod_mul_reciprocal(r, r, r, &recp, ctx))
273 goto err;
274 }
275
276 /* wvalue will be an odd number < 2^window */
277 if (!BN_mod_mul_reciprocal(r, r, val[wvalue >> 1], &recp, ctx))
278 goto err;
279
280 /* move the 'window' down further */
281 wstart -= wend + 1;
282 wvalue = 0;
283 start = 0;
284 if (wstart < 0)
285 break;
286 }
287 ret = 1;
288 err:
289 BN_CTX_end(ctx);
290 BN_RECP_CTX_free(&recp);
291 bn_check_top(r);
292 return ret;
293}
294
295int BN_mod_exp_mont(BIGNUM *rr, const BIGNUM *a, const BIGNUM *p,
296 const BIGNUM *m, BN_CTX *ctx, BN_MONT_CTX *in_mont)
297{
298 int i, j, bits, ret = 0, wstart, wend, window, wvalue;
299 int start = 1;
300 BIGNUM *d, *r;
301 const BIGNUM *aa;
302 /* Table of variables obtained from 'ctx' */
303 BIGNUM *val[TABLE_SIZE32];
304 BN_MONT_CTX *mont = NULL((void*)0);
305
306 if (BN_get_flags(p, BN_FLG_CONSTTIME0x04) != 0
307 || BN_get_flags(a, BN_FLG_CONSTTIME0x04) != 0
308 || BN_get_flags(m, BN_FLG_CONSTTIME0x04) != 0) {
309 return BN_mod_exp_mont_consttime(rr, a, p, m, ctx, in_mont);
310 }
311
312 bn_check_top(a);
313 bn_check_top(p);
314 bn_check_top(m);
315
316 if (!BN_is_odd(m)) {
317 ERR_raise(ERR_LIB_BN, BN_R_CALLED_WITH_EVEN_MODULUS)(ERR_new(), ERR_set_debug("../deps/openssl/openssl/crypto/bn/bn_exp.c"
,317,__func__), ERR_set_error)((3),(102),((void*)0))
;
318 return 0;
319 }
320 bits = BN_num_bits(p);
321 if (bits == 0) {
322 /* x**0 mod 1, or x**0 mod -1 is still zero. */
323 if (BN_abs_is_word(m, 1)) {
324 ret = 1;
325 BN_zero(rr)BN_zero_ex(rr);
326 } else {
327 ret = BN_one(rr)(BN_set_word((rr),1));
328 }
329 return ret;
330 }
331
332 BN_CTX_start(ctx);
333 d = BN_CTX_get(ctx);
334 r = BN_CTX_get(ctx);
335 val[0] = BN_CTX_get(ctx);
336 if (val[0] == NULL((void*)0))
337 goto err;
338
339 /*
340 * If this is not done, things will break in the montgomery part
341 */
342
343 if (in_mont != NULL((void*)0))
344 mont = in_mont;
345 else {
346 if ((mont = BN_MONT_CTX_new()) == NULL((void*)0))
347 goto err;
348 if (!BN_MONT_CTX_set(mont, m, ctx))
349 goto err;
350 }
351
352 if (a->neg || BN_ucmp(a, m) >= 0) {
353 if (!BN_nnmod(val[0], a, m, ctx))
354 goto err;
355 aa = val[0];
356 } else
357 aa = a;
358 if (!bn_to_mont_fixed_top(val[0], aa, mont, ctx))
359 goto err; /* 1 */
360
361 window = BN_window_bits_for_exponent_size(bits)((bits) > 671 ? 6 : (bits) > 239 ? 5 : (bits) > 79 ?
4 : (bits) > 23 ? 3 : 1)
;
362 if (window > 1) {
363 if (!bn_mul_mont_fixed_top(d, val[0], val[0], mont, ctx))
364 goto err; /* 2 */
365 j = 1 << (window - 1);
366 for (i = 1; i < j; i++) {
367 if (((val[i] = BN_CTX_get(ctx)) == NULL((void*)0)) ||
368 !bn_mul_mont_fixed_top(val[i], val[i - 1], d, mont, ctx))
369 goto err;
370 }
371 }
372
373 start = 1; /* This is used to avoid multiplication etc
374 * when there is only the value '1' in the
375 * buffer. */
376 wvalue = 0; /* The 'value' of the window */
377 wstart = bits - 1; /* The top bit of the window */
378 wend = 0; /* The bottom bit of the window */
Value stored to 'wend' is never read
379
380#if 1 /* by Shay Gueron's suggestion */
381 j = m->top; /* borrow j */
382 if (m->d[j - 1] & (((BN_ULONGunsigned long)1) << (BN_BITS2(8 * 8) - 1))) {
383 if (bn_wexpand(r, j) == NULL((void*)0))
384 goto err;
385 /* 2^(top*BN_BITS2) - m */
386 r->d[0] = (0 - m->d[0]) & BN_MASK2(0xffffffffffffffffL);
387 for (i = 1; i < j; i++)
388 r->d[i] = (~m->d[i]) & BN_MASK2(0xffffffffffffffffL);
389 r->top = j;
390 r->flags |= BN_FLG_FIXED_TOP0;
391 } else
392#endif
393 if (!bn_to_mont_fixed_top(r, BN_value_one(), mont, ctx))
394 goto err;
395 for (;;) {
396 if (BN_is_bit_set(p, wstart) == 0) {
397 if (!start) {
398 if (!bn_mul_mont_fixed_top(r, r, r, mont, ctx))
399 goto err;
400 }
401 if (wstart == 0)
402 break;
403 wstart--;
404 continue;
405 }
406 /*
407 * We now have wstart on a 'set' bit, we now need to work out how bit
408 * a window to do. To do this we need to scan forward until the last
409 * set bit before the end of the window
410 */
411 wvalue = 1;
412 wend = 0;
413 for (i = 1; i < window; i++) {
414 if (wstart - i < 0)
415 break;
416 if (BN_is_bit_set(p, wstart - i)) {
417 wvalue <<= (i - wend);
418 wvalue |= 1;
419 wend = i;
420 }
421 }
422
423 /* wend is the size of the current window */
424 j = wend + 1;
425 /* add the 'bytes above' */
426 if (!start)
427 for (i = 0; i < j; i++) {
428 if (!bn_mul_mont_fixed_top(r, r, r, mont, ctx))
429 goto err;
430 }
431
432 /* wvalue will be an odd number < 2^window */
433 if (!bn_mul_mont_fixed_top(r, r, val[wvalue >> 1], mont, ctx))
434 goto err;
435
436 /* move the 'window' down further */
437 wstart -= wend + 1;
438 wvalue = 0;
439 start = 0;
440 if (wstart < 0)
441 break;
442 }
443 /*
444 * Done with zero-padded intermediate BIGNUMs. Final BN_from_montgomery
445 * removes padding [if any] and makes return value suitable for public
446 * API consumer.
447 */
448#if defined(SPARC_T4_MONT)
449 if (OPENSSL_sparcv9cap_P[0] & (SPARCV9_VIS3 | SPARCV9_PREFER_FPU)) {
450 j = mont->N.top; /* borrow j */
451 val[0]->d[0] = 1; /* borrow val[0] */
452 for (i = 1; i < j; i++)
453 val[0]->d[i] = 0;
454 val[0]->top = j;
455 if (!BN_mod_mul_montgomery(rr, r, val[0], mont, ctx))
456 goto err;
457 } else
458#endif
459 if (!BN_from_montgomery(rr, r, mont, ctx))
460 goto err;
461 ret = 1;
462 err:
463 if (in_mont == NULL((void*)0))
464 BN_MONT_CTX_free(mont);
465 BN_CTX_end(ctx);
466 bn_check_top(rr);
467 return ret;
468}
469
470static BN_ULONGunsigned long bn_get_bits(const BIGNUM *a, int bitpos)
471{
472 BN_ULONGunsigned long ret = 0;
473 int wordpos;
474
475 wordpos = bitpos / BN_BITS2(8 * 8);
476 bitpos %= BN_BITS2(8 * 8);
477 if (wordpos >= 0 && wordpos < a->top) {
478 ret = a->d[wordpos] & BN_MASK2(0xffffffffffffffffL);
479 if (bitpos) {
480 ret >>= bitpos;
481 if (++wordpos < a->top)
482 ret |= a->d[wordpos] << (BN_BITS2(8 * 8) - bitpos);
483 }
484 }
485
486 return ret & BN_MASK2(0xffffffffffffffffL);
487}
488
489/*
490 * BN_mod_exp_mont_consttime() stores the precomputed powers in a specific
491 * layout so that accessing any of these table values shows the same access
492 * pattern as far as cache lines are concerned. The following functions are
493 * used to transfer a BIGNUM from/to that table.
494 */
495
496static int MOD_EXP_CTIME_COPY_TO_PREBUF(const BIGNUM *b, int top,
497 unsigned char *buf, int idx,
498 int window)
499{
500 int i, j;
501 int width = 1 << window;
502 BN_ULONGunsigned long *table = (BN_ULONGunsigned long *)buf;
503
504 if (top > b->top)
505 top = b->top; /* this works because 'buf' is explicitly
506 * zeroed */
507 for (i = 0, j = idx; i < top; i++, j += width) {
508 table[j] = b->d[i];
509 }
510
511 return 1;
512}
513
514static int MOD_EXP_CTIME_COPY_FROM_PREBUF(BIGNUM *b, int top,
515 unsigned char *buf, int idx,
516 int window)
517{
518 int i, j;
519 int width = 1 << window;
520 /*
521 * We declare table 'volatile' in order to discourage compiler
522 * from reordering loads from the table. Concern is that if
523 * reordered in specific manner loads might give away the
524 * information we are trying to conceal. Some would argue that
525 * compiler can reorder them anyway, but it can as well be
526 * argued that doing so would be violation of standard...
527 */
528 volatile BN_ULONGunsigned long *table = (volatile BN_ULONGunsigned long *)buf;
529
530 if (bn_wexpand(b, top) == NULL((void*)0))
531 return 0;
532
533 if (window <= 3) {
534 for (i = 0; i < top; i++, table += width) {
535 BN_ULONGunsigned long acc = 0;
536
537 for (j = 0; j < width; j++) {
538 acc |= table[j] &
539 ((BN_ULONGunsigned long)0 - (constant_time_eq_int(j,idx)&1));
540 }
541
542 b->d[i] = acc;
543 }
544 } else {
545 int xstride = 1 << (window - 2);
546 BN_ULONGunsigned long y0, y1, y2, y3;
547
548 i = idx >> (window - 2); /* equivalent of idx / xstride */
549 idx &= xstride - 1; /* equivalent of idx % xstride */
550
551 y0 = (BN_ULONGunsigned long)0 - (constant_time_eq_int(i,0)&1);
552 y1 = (BN_ULONGunsigned long)0 - (constant_time_eq_int(i,1)&1);
553 y2 = (BN_ULONGunsigned long)0 - (constant_time_eq_int(i,2)&1);
554 y3 = (BN_ULONGunsigned long)0 - (constant_time_eq_int(i,3)&1);
555
556 for (i = 0; i < top; i++, table += width) {
557 BN_ULONGunsigned long acc = 0;
558
559 for (j = 0; j < xstride; j++) {
560 acc |= ( (table[j + 0 * xstride] & y0) |
561 (table[j + 1 * xstride] & y1) |
562 (table[j + 2 * xstride] & y2) |
563 (table[j + 3 * xstride] & y3) )
564 & ((BN_ULONGunsigned long)0 - (constant_time_eq_int(j,idx)&1));
565 }
566
567 b->d[i] = acc;
568 }
569 }
570
571 b->top = top;
572 b->flags |= BN_FLG_FIXED_TOP0;
573 return 1;
574}
575
576/*
577 * Given a pointer value, compute the next address that is a cache line
578 * multiple.
579 */
580#define MOD_EXP_CTIME_ALIGN(x_)((unsigned char*)(x_) + (( 64 ) - (((size_t)(x_)) & ((( 64
) - 1)))))
\
581 ((unsigned char*)(x_) + (MOD_EXP_CTIME_MIN_CACHE_LINE_WIDTH( 64 ) - (((size_t)(x_)) & (MOD_EXP_CTIME_MIN_CACHE_LINE_MASK(( 64 ) - 1)))))
582
583/*
584 * This variant of BN_mod_exp_mont() uses fixed windows and the special
585 * precomputation memory layout to limit data-dependency to a minimum to
586 * protect secret exponents (cf. the hyper-threading timing attacks pointed
587 * out by Colin Percival,
588 * http://www.daemonology.net/hyperthreading-considered-harmful/)
589 */
590int BN_mod_exp_mont_consttime(BIGNUM *rr, const BIGNUM *a, const BIGNUM *p,
591 const BIGNUM *m, BN_CTX *ctx,
592 BN_MONT_CTX *in_mont)
593{
594 int i, bits, ret = 0, window, wvalue, wmask, window0;
595 int top;
596 BN_MONT_CTX *mont = NULL((void*)0);
597
598 int numPowers;
599 unsigned char *powerbufFree = NULL((void*)0);
600 int powerbufLen = 0;
601 unsigned char *powerbuf = NULL((void*)0);
602 BIGNUM tmp, am;
603#if defined(SPARC_T4_MONT)
604 unsigned int t4 = 0;
605#endif
606
607 bn_check_top(a);
608 bn_check_top(p);
609 bn_check_top(m);
610
611 if (!BN_is_odd(m)) {
612 ERR_raise(ERR_LIB_BN, BN_R_CALLED_WITH_EVEN_MODULUS)(ERR_new(), ERR_set_debug("../deps/openssl/openssl/crypto/bn/bn_exp.c"
,612,__func__), ERR_set_error)((3),(102),((void*)0))
;
613 return 0;
614 }
615
616 top = m->top;
617
618 /*
619 * Use all bits stored in |p|, rather than |BN_num_bits|, so we do not leak
620 * whether the top bits are zero.
621 */
622 bits = p->top * BN_BITS2(8 * 8);
623 if (bits == 0) {
624 /* x**0 mod 1, or x**0 mod -1 is still zero. */
625 if (BN_abs_is_word(m, 1)) {
626 ret = 1;
627 BN_zero(rr)BN_zero_ex(rr);
628 } else {
629 ret = BN_one(rr)(BN_set_word((rr),1));
630 }
631 return ret;
632 }
633
634 BN_CTX_start(ctx);
635
636 /*
637 * Allocate a montgomery context if it was not supplied by the caller. If
638 * this is not done, things will break in the montgomery part.
639 */
640 if (in_mont != NULL((void*)0))
641 mont = in_mont;
642 else {
643 if ((mont = BN_MONT_CTX_new()) == NULL((void*)0))
644 goto err;
645 if (!BN_MONT_CTX_set(mont, m, ctx))
646 goto err;
647 }
648
649 if (a->neg || BN_ucmp(a, m) >= 0) {
650 BIGNUM *reduced = BN_CTX_get(ctx);
651 if (reduced == NULL((void*)0)
652 || !BN_nnmod(reduced, a, m, ctx)) {
653 goto err;
654 }
655 a = reduced;
656 }
657
658#ifdef RSAZ_ENABLED
659 /*
660 * If the size of the operands allow it, perform the optimized
661 * RSAZ exponentiation. For further information see
662 * crypto/bn/rsaz_exp.c and accompanying assembly modules.
663 */
664 if ((16 == a->top) && (16 == p->top) && (BN_num_bits(m) == 1024)
665 && rsaz_avx2_eligible()) {
666 if (NULL((void*)0) == bn_wexpand(rr, 16))
667 goto err;
668 RSAZ_1024_mod_exp_avx2(rr->d, a->d, p->d, m->d, mont->RR.d,
669 mont->n0[0]);
670 rr->top = 16;
671 rr->neg = 0;
672 bn_correct_top(rr);
673 ret = 1;
674 goto err;
675 } else if ((8 == a->top) && (8 == p->top) && (BN_num_bits(m) == 512)) {
676 if (NULL((void*)0) == bn_wexpand(rr, 8))
677 goto err;
678 RSAZ_512_mod_exp(rr->d, a->d, p->d, m->d, mont->n0[0], mont->RR.d);
679 rr->top = 8;
680 rr->neg = 0;
681 bn_correct_top(rr);
682 ret = 1;
683 goto err;
684 }
685#endif
686
687 /* Get the window size to use with size of p. */
688 window = BN_window_bits_for_ctime_exponent_size(bits)((bits) > 937 ? 6 : (bits) > 306 ? 5 : (bits) > 89 ?
4 : (bits) > 22 ? 3 : 1)
;
689#if defined(SPARC_T4_MONT)
690 if (window >= 5 && (top & 15) == 0 && top <= 64 &&
691 (OPENSSL_sparcv9cap_P[1] & (CFR_MONTMUL | CFR_MONTSQR)) ==
692 (CFR_MONTMUL | CFR_MONTSQR) && (t4 = OPENSSL_sparcv9cap_P[0]))
693 window = 5;
694 else
695#endif
696#if defined(OPENSSL_BN_ASM_MONT51)
697 if (window >= 5) {
698 window = 5; /* ~5% improvement for RSA2048 sign, and even
699 * for RSA4096 */
700 /* reserve space for mont->N.d[] copy */
701 powerbufLen += top * sizeof(mont->N.d[0]);
702 }
703#endif
704 (void)0;
705
706 /*
707 * Allocate a buffer large enough to hold all of the pre-computed powers
708 * of am, am itself and tmp.
709 */
710 numPowers = 1 << window;
711 powerbufLen += sizeof(m->d[0]) * (top * numPowers +
712 ((2 * top) >
713 numPowers ? (2 * top) : numPowers));
714#ifdef alloca
715 if (powerbufLen < 3072)
716 powerbufFree =
717 alloca(powerbufLen + MOD_EXP_CTIME_MIN_CACHE_LINE_WIDTH)__builtin_alloca (powerbufLen + ( 64 ));
718 else
719#endif
720 if ((powerbufFree =
721 OPENSSL_malloc(powerbufLen + MOD_EXP_CTIME_MIN_CACHE_LINE_WIDTH)CRYPTO_malloc(powerbufLen + ( 64 ), "../deps/openssl/openssl/crypto/bn/bn_exp.c"
, 721)
)
722 == NULL((void*)0))
723 goto err;
724
725 powerbuf = MOD_EXP_CTIME_ALIGN(powerbufFree)((unsigned char*)(powerbufFree) + (( 64 ) - (((size_t)(powerbufFree
)) & ((( 64 ) - 1)))))
;
726 memset(powerbuf, 0, powerbufLen);
727
728#ifdef alloca
729 if (powerbufLen < 3072)
730 powerbufFree = NULL((void*)0);
731#endif
732
733 /* lay down tmp and am right after powers table */
734 tmp.d = (BN_ULONGunsigned long *)(powerbuf + sizeof(m->d[0]) * top * numPowers);
735 am.d = tmp.d + top;
736 tmp.top = am.top = 0;
737 tmp.dmax = am.dmax = top;
738 tmp.neg = am.neg = 0;
739 tmp.flags = am.flags = BN_FLG_STATIC_DATA0x02;
740
741 /* prepare a^0 in Montgomery domain */
742#if 1 /* by Shay Gueron's suggestion */
743 if (m->d[top - 1] & (((BN_ULONGunsigned long)1) << (BN_BITS2(8 * 8) - 1))) {
744 /* 2^(top*BN_BITS2) - m */
745 tmp.d[0] = (0 - m->d[0]) & BN_MASK2(0xffffffffffffffffL);
746 for (i = 1; i < top; i++)
747 tmp.d[i] = (~m->d[i]) & BN_MASK2(0xffffffffffffffffL);
748 tmp.top = top;
749 } else
750#endif
751 if (!bn_to_mont_fixed_top(&tmp, BN_value_one(), mont, ctx))
752 goto err;
753
754 /* prepare a^1 in Montgomery domain */
755 if (!bn_to_mont_fixed_top(&am, a, mont, ctx))
756 goto err;
757
758#if defined(SPARC_T4_MONT)
759 if (t4) {
760 typedef int (*bn_pwr5_mont_f) (BN_ULONGunsigned long *tp, const BN_ULONGunsigned long *np,
761 const BN_ULONGunsigned long *n0, const void *table,
762 int power, int bits);
763 int bn_pwr5_mont_t4_8(BN_ULONGunsigned long *tp, const BN_ULONGunsigned long *np,
764 const BN_ULONGunsigned long *n0, const void *table,
765 int power, int bits);
766 int bn_pwr5_mont_t4_16(BN_ULONGunsigned long *tp, const BN_ULONGunsigned long *np,
767 const BN_ULONGunsigned long *n0, const void *table,
768 int power, int bits);
769 int bn_pwr5_mont_t4_24(BN_ULONGunsigned long *tp, const BN_ULONGunsigned long *np,
770 const BN_ULONGunsigned long *n0, const void *table,
771 int power, int bits);
772 int bn_pwr5_mont_t4_32(BN_ULONGunsigned long *tp, const BN_ULONGunsigned long *np,
773 const BN_ULONGunsigned long *n0, const void *table,
774 int power, int bits);
775 static const bn_pwr5_mont_f pwr5_funcs[4] = {
776 bn_pwr5_mont_t4_8, bn_pwr5_mont_t4_16,
777 bn_pwr5_mont_t4_24, bn_pwr5_mont_t4_32
778 };
779 bn_pwr5_mont_f pwr5_worker = pwr5_funcs[top / 16 - 1];
780
781 typedef int (*bn_mul_mont_f) (BN_ULONGunsigned long *rp, const BN_ULONGunsigned long *ap,
782 const void *bp, const BN_ULONGunsigned long *np,
783 const BN_ULONGunsigned long *n0);
784 int bn_mul_mont_t4_8(BN_ULONGunsigned long *rp, const BN_ULONGunsigned long *ap, const void *bp,
785 const BN_ULONGunsigned long *np, const BN_ULONGunsigned long *n0);
786 int bn_mul_mont_t4_16(BN_ULONGunsigned long *rp, const BN_ULONGunsigned long *ap,
787 const void *bp, const BN_ULONGunsigned long *np,
788 const BN_ULONGunsigned long *n0);
789 int bn_mul_mont_t4_24(BN_ULONGunsigned long *rp, const BN_ULONGunsigned long *ap,
790 const void *bp, const BN_ULONGunsigned long *np,
791 const BN_ULONGunsigned long *n0);
792 int bn_mul_mont_t4_32(BN_ULONGunsigned long *rp, const BN_ULONGunsigned long *ap,
793 const void *bp, const BN_ULONGunsigned long *np,
794 const BN_ULONGunsigned long *n0);
795 static const bn_mul_mont_f mul_funcs[4] = {
796 bn_mul_mont_t4_8, bn_mul_mont_t4_16,
797 bn_mul_mont_t4_24, bn_mul_mont_t4_32
798 };
799 bn_mul_mont_f mul_worker = mul_funcs[top / 16 - 1];
800
801 void bn_mul_mont_vis3(BN_ULONGunsigned long *rp, const BN_ULONGunsigned long *ap,
802 const void *bp, const BN_ULONGunsigned long *np,
803 const BN_ULONGunsigned long *n0, int num);
804 void bn_mul_mont_t4(BN_ULONGunsigned long *rp, const BN_ULONGunsigned long *ap,
805 const void *bp, const BN_ULONGunsigned long *np,
806 const BN_ULONGunsigned long *n0, int num);
807 void bn_mul_mont_gather5_t4(BN_ULONGunsigned long *rp, const BN_ULONGunsigned long *ap,
808 const void *table, const BN_ULONGunsigned long *np,
809 const BN_ULONGunsigned long *n0, int num, int power);
810 void bn_flip_n_scatter5_t4(const BN_ULONGunsigned long *inp, size_t num,
811 void *table, size_t power);
812 void bn_gather5_t4(BN_ULONGunsigned long *out, size_t num,
813 void *table, size_t power);
814 void bn_flip_t4(BN_ULONGunsigned long *dst, BN_ULONGunsigned long *src, size_t num);
815
816 BN_ULONGunsigned long *np = mont->N.d, *n0 = mont->n0;
817 int stride = 5 * (6 - (top / 16 - 1)); /* multiple of 5, but less
818 * than 32 */
819
820 /*
821 * BN_to_montgomery can contaminate words above .top [in
822 * BN_DEBUG build...
823 */
824 for (i = am.top; i < top; i++)
825 am.d[i] = 0;
826 for (i = tmp.top; i < top; i++)
827 tmp.d[i] = 0;
828
829 bn_flip_n_scatter5_t4(tmp.d, top, powerbuf, 0);
830 bn_flip_n_scatter5_t4(am.d, top, powerbuf, 1);
831 if (!(*mul_worker) (tmp.d, am.d, am.d, np, n0) &&
832 !(*mul_worker) (tmp.d, am.d, am.d, np, n0))
833 bn_mul_mont_vis3(tmp.d, am.d, am.d, np, n0, top);
834 bn_flip_n_scatter5_t4(tmp.d, top, powerbuf, 2);
835
836 for (i = 3; i < 32; i++) {
837 /* Calculate a^i = a^(i-1) * a */
838 if (!(*mul_worker) (tmp.d, tmp.d, am.d, np, n0) &&
839 !(*mul_worker) (tmp.d, tmp.d, am.d, np, n0))
840 bn_mul_mont_vis3(tmp.d, tmp.d, am.d, np, n0, top);
841 bn_flip_n_scatter5_t4(tmp.d, top, powerbuf, i);
842 }
843
844 /* switch to 64-bit domain */
845 np = alloca(top * sizeof(BN_ULONG))__builtin_alloca (top * sizeof(unsigned long));
846 top /= 2;
847 bn_flip_t4(np, mont->N.d, top);
848
849 /*
850 * The exponent may not have a whole number of fixed-size windows.
851 * To simplify the main loop, the initial window has between 1 and
852 * full-window-size bits such that what remains is always a whole
853 * number of windows
854 */
855 window0 = (bits - 1) % 5 + 1;
856 wmask = (1 << window0) - 1;
857 bits -= window0;
858 wvalue = bn_get_bits(p, bits) & wmask;
859 bn_gather5_t4(tmp.d, top, powerbuf, wvalue);
860
861 /*
862 * Scan the exponent one window at a time starting from the most
863 * significant bits.
864 */
865 while (bits > 0) {
866 if (bits < stride)
867 stride = bits;
868 bits -= stride;
869 wvalue = bn_get_bits(p, bits);
870
871 if ((*pwr5_worker) (tmp.d, np, n0, powerbuf, wvalue, stride))
872 continue;
873 /* retry once and fall back */
874 if ((*pwr5_worker) (tmp.d, np, n0, powerbuf, wvalue, stride))
875 continue;
876
877 bits += stride - 5;
878 wvalue >>= stride - 5;
879 wvalue &= 31;
880 bn_mul_mont_t4(tmp.d, tmp.d, tmp.d, np, n0, top);
881 bn_mul_mont_t4(tmp.d, tmp.d, tmp.d, np, n0, top);
882 bn_mul_mont_t4(tmp.d, tmp.d, tmp.d, np, n0, top);
883 bn_mul_mont_t4(tmp.d, tmp.d, tmp.d, np, n0, top);
884 bn_mul_mont_t4(tmp.d, tmp.d, tmp.d, np, n0, top);
885 bn_mul_mont_gather5_t4(tmp.d, tmp.d, powerbuf, np, n0, top,
886 wvalue);
887 }
888
889 bn_flip_t4(tmp.d, tmp.d, top);
890 top *= 2;
891 /* back to 32-bit domain */
892 tmp.top = top;
893 bn_correct_top(&tmp);
894 OPENSSL_cleanse(np, top * sizeof(BN_ULONGunsigned long));
895 } else
896#endif
897#if defined(OPENSSL_BN_ASM_MONT51)
898 if (window == 5 && top > 1) {
899 /*
900 * This optimization uses ideas from https://eprint.iacr.org/2011/239,
901 * specifically optimization of cache-timing attack countermeasures,
902 * pre-computation optimization, and Almost Montgomery Multiplication.
903 *
904 * The paper discusses a 4-bit window to optimize 512-bit modular
905 * exponentiation, used in RSA-1024 with CRT, but RSA-1024 is no longer
906 * important.
907 *
908 * |bn_mul_mont_gather5| and |bn_power5| implement the "almost"
909 * reduction variant, so the values here may not be fully reduced.
910 * They are bounded by R (i.e. they fit in |top| words), not |m|.
911 * Additionally, we pass these "almost" reduced inputs into
912 * |bn_mul_mont|, which implements the normal reduction variant.
913 * Given those inputs, |bn_mul_mont| may not give reduced
914 * output, but it will still produce "almost" reduced output.
915 */
916 void bn_mul_mont_gather5(BN_ULONGunsigned long *rp, const BN_ULONGunsigned long *ap,
917 const void *table, const BN_ULONGunsigned long *np,
918 const BN_ULONGunsigned long *n0, int num, int power);
919 void bn_scatter5(const BN_ULONGunsigned long *inp, size_t num,
920 void *table, size_t power);
921 void bn_gather5(BN_ULONGunsigned long *out, size_t num, void *table, size_t power);
922 void bn_power5(BN_ULONGunsigned long *rp, const BN_ULONGunsigned long *ap,
923 const void *table, const BN_ULONGunsigned long *np,
924 const BN_ULONGunsigned long *n0, int num, int power);
925 int bn_get_bits5(const BN_ULONGunsigned long *ap, int off);
926
927 BN_ULONGunsigned long *n0 = mont->n0, *np;
928
929 /*
930 * BN_to_montgomery can contaminate words above .top [in
931 * BN_DEBUG build...
932 */
933 for (i = am.top; i < top; i++)
934 am.d[i] = 0;
935 for (i = tmp.top; i < top; i++)
936 tmp.d[i] = 0;
937
938 /*
939 * copy mont->N.d[] to improve cache locality
940 */
941 for (np = am.d + top, i = 0; i < top; i++)
942 np[i] = mont->N.d[i];
943
944 bn_scatter5(tmp.d, top, powerbuf, 0);
945 bn_scatter5(am.d, am.top, powerbuf, 1);
946 bn_mul_mont(tmp.d, am.d, am.d, np, n0, top);
947 bn_scatter5(tmp.d, top, powerbuf, 2);
948
949# if 0
950 for (i = 3; i < 32; i++) {
951 /* Calculate a^i = a^(i-1) * a */
952 bn_mul_mont_gather5(tmp.d, am.d, powerbuf, np, n0, top, i - 1);
953 bn_scatter5(tmp.d, top, powerbuf, i);
954 }
955# else
956 /* same as above, but uses squaring for 1/2 of operations */
957 for (i = 4; i < 32; i *= 2) {
958 bn_mul_mont(tmp.d, tmp.d, tmp.d, np, n0, top);
959 bn_scatter5(tmp.d, top, powerbuf, i);
960 }
961 for (i = 3; i < 8; i += 2) {
962 int j;
963 bn_mul_mont_gather5(tmp.d, am.d, powerbuf, np, n0, top, i - 1);
964 bn_scatter5(tmp.d, top, powerbuf, i);
965 for (j = 2 * i; j < 32; j *= 2) {
966 bn_mul_mont(tmp.d, tmp.d, tmp.d, np, n0, top);
967 bn_scatter5(tmp.d, top, powerbuf, j);
968 }
969 }
970 for (; i < 16; i += 2) {
971 bn_mul_mont_gather5(tmp.d, am.d, powerbuf, np, n0, top, i - 1);
972 bn_scatter5(tmp.d, top, powerbuf, i);
973 bn_mul_mont(tmp.d, tmp.d, tmp.d, np, n0, top);
974 bn_scatter5(tmp.d, top, powerbuf, 2 * i);
975 }
976 for (; i < 32; i += 2) {
977 bn_mul_mont_gather5(tmp.d, am.d, powerbuf, np, n0, top, i - 1);
978 bn_scatter5(tmp.d, top, powerbuf, i);
979 }
980# endif
981 /*
982 * The exponent may not have a whole number of fixed-size windows.
983 * To simplify the main loop, the initial window has between 1 and
984 * full-window-size bits such that what remains is always a whole
985 * number of windows
986 */
987 window0 = (bits - 1) % 5 + 1;
988 wmask = (1 << window0) - 1;
989 bits -= window0;
990 wvalue = bn_get_bits(p, bits) & wmask;
991 bn_gather5(tmp.d, top, powerbuf, wvalue);
992
993 /*
994 * Scan the exponent one window at a time starting from the most
995 * significant bits.
996 */
997 if (top & 7) {
998 while (bits > 0) {
999 bn_mul_mont(tmp.d, tmp.d, tmp.d, np, n0, top);
1000 bn_mul_mont(tmp.d, tmp.d, tmp.d, np, n0, top);
1001 bn_mul_mont(tmp.d, tmp.d, tmp.d, np, n0, top);
1002 bn_mul_mont(tmp.d, tmp.d, tmp.d, np, n0, top);
1003 bn_mul_mont(tmp.d, tmp.d, tmp.d, np, n0, top);
1004 bn_mul_mont_gather5(tmp.d, tmp.d, powerbuf, np, n0, top,
1005 bn_get_bits5(p->d, bits -= 5));
1006 }
1007 } else {
1008 while (bits > 0) {
1009 bn_power5(tmp.d, tmp.d, powerbuf, np, n0, top,
1010 bn_get_bits5(p->d, bits -= 5));
1011 }
1012 }
1013
1014 tmp.top = top;
1015 /*
1016 * The result is now in |tmp| in Montgomery form, but it may not be
1017 * fully reduced. This is within bounds for |BN_from_montgomery|
1018 * (tmp < R <= m*R) so it will, when converting from Montgomery form,
1019 * produce a fully reduced result.
1020 *
1021 * This differs from Figure 2 of the paper, which uses AMM(h, 1) to
1022 * convert from Montgomery form with unreduced output, followed by an
1023 * extra reduction step. In the paper's terminology, we replace
1024 * steps 9 and 10 with MM(h, 1).
1025 */
1026 } else
1027#endif
1028 {
1029 if (!MOD_EXP_CTIME_COPY_TO_PREBUF(&tmp, top, powerbuf, 0, window))
1030 goto err;
1031 if (!MOD_EXP_CTIME_COPY_TO_PREBUF(&am, top, powerbuf, 1, window))
1032 goto err;
1033
1034 /*
1035 * If the window size is greater than 1, then calculate
1036 * val[i=2..2^winsize-1]. Powers are computed as a*a^(i-1) (even
1037 * powers could instead be computed as (a^(i/2))^2 to use the slight
1038 * performance advantage of sqr over mul).
1039 */
1040 if (window > 1) {
1041 if (!bn_mul_mont_fixed_top(&tmp, &am, &am, mont, ctx))
1042 goto err;
1043 if (!MOD_EXP_CTIME_COPY_TO_PREBUF(&tmp, top, powerbuf, 2,
1044 window))
1045 goto err;
1046 for (i = 3; i < numPowers; i++) {
1047 /* Calculate a^i = a^(i-1) * a */
1048 if (!bn_mul_mont_fixed_top(&tmp, &am, &tmp, mont, ctx))
1049 goto err;
1050 if (!MOD_EXP_CTIME_COPY_TO_PREBUF(&tmp, top, powerbuf, i,
1051 window))
1052 goto err;
1053 }
1054 }
1055
1056 /*
1057 * The exponent may not have a whole number of fixed-size windows.
1058 * To simplify the main loop, the initial window has between 1 and
1059 * full-window-size bits such that what remains is always a whole
1060 * number of windows
1061 */
1062 window0 = (bits - 1) % window + 1;
1063 wmask = (1 << window0) - 1;
1064 bits -= window0;
1065 wvalue = bn_get_bits(p, bits) & wmask;
1066 if (!MOD_EXP_CTIME_COPY_FROM_PREBUF(&tmp, top, powerbuf, wvalue,
1067 window))
1068 goto err;
1069
1070 wmask = (1 << window) - 1;
1071 /*
1072 * Scan the exponent one window at a time starting from the most
1073 * significant bits.
1074 */
1075 while (bits > 0) {
1076
1077 /* Square the result window-size times */
1078 for (i = 0; i < window; i++)
1079 if (!bn_mul_mont_fixed_top(&tmp, &tmp, &tmp, mont, ctx))
1080 goto err;
1081
1082 /*
1083 * Get a window's worth of bits from the exponent
1084 * This avoids calling BN_is_bit_set for each bit, which
1085 * is not only slower but also makes each bit vulnerable to
1086 * EM (and likely other) side-channel attacks like One&Done
1087 * (for details see "One&Done: A Single-Decryption EM-Based
1088 * Attack on OpenSSL's Constant-Time Blinded RSA" by M. Alam,
1089 * H. Khan, M. Dey, N. Sinha, R. Callan, A. Zajic, and
1090 * M. Prvulovic, in USENIX Security'18)
1091 */
1092 bits -= window;
1093 wvalue = bn_get_bits(p, bits) & wmask;
1094 /*
1095 * Fetch the appropriate pre-computed value from the pre-buf
1096 */
1097 if (!MOD_EXP_CTIME_COPY_FROM_PREBUF(&am, top, powerbuf, wvalue,
1098 window))
1099 goto err;
1100
1101 /* Multiply the result into the intermediate result */
1102 if (!bn_mul_mont_fixed_top(&tmp, &tmp, &am, mont, ctx))
1103 goto err;
1104 }
1105 }
1106
1107 /*
1108 * Done with zero-padded intermediate BIGNUMs. Final BN_from_montgomery
1109 * removes padding [if any] and makes return value suitable for public
1110 * API consumer.
1111 */
1112#if defined(SPARC_T4_MONT)
1113 if (OPENSSL_sparcv9cap_P[0] & (SPARCV9_VIS3 | SPARCV9_PREFER_FPU)) {
1114 am.d[0] = 1; /* borrow am */
1115 for (i = 1; i < top; i++)
1116 am.d[i] = 0;
1117 if (!BN_mod_mul_montgomery(rr, &tmp, &am, mont, ctx))
1118 goto err;
1119 } else
1120#endif
1121 if (!BN_from_montgomery(rr, &tmp, mont, ctx))
1122 goto err;
1123 ret = 1;
1124 err:
1125 if (in_mont == NULL((void*)0))
1126 BN_MONT_CTX_free(mont);
1127 if (powerbuf != NULL((void*)0)) {
1128 OPENSSL_cleanse(powerbuf, powerbufLen);
1129 OPENSSL_free(powerbufFree)CRYPTO_free(powerbufFree, "../deps/openssl/openssl/crypto/bn/bn_exp.c"
, 1129)
;
1130 }
1131 BN_CTX_end(ctx);
1132 return ret;
1133}
1134
1135int BN_mod_exp_mont_word(BIGNUM *rr, BN_ULONGunsigned long a, const BIGNUM *p,
1136 const BIGNUM *m, BN_CTX *ctx, BN_MONT_CTX *in_mont)
1137{
1138 BN_MONT_CTX *mont = NULL((void*)0);
1139 int b, bits, ret = 0;
1140 int r_is_one;
1141 BN_ULONGunsigned long w, next_w;
1142 BIGNUM *r, *t;
1143 BIGNUM *swap_tmp;
1144#define BN_MOD_MUL_WORD(r, w, m)(BN_mul_word(r, (w)) && ( (BN_div(((void*)0),(t),(r),
(m),(ctx)) && (swap_tmp = r, r = t, t = swap_tmp, 1))
))
\
1145 (BN_mul_word(r, (w)) && \
1146 (/* BN_ucmp(r, (m)) < 0 ? 1 :*/ \
1147 (BN_mod(t, r, m, ctx)BN_div(((void*)0),(t),(r),(m),(ctx)) && (swap_tmp = r, r = t, t = swap_tmp, 1))))
1148 /*
1149 * BN_MOD_MUL_WORD is only used with 'w' large, so the BN_ucmp test is
1150 * probably more overhead than always using BN_mod (which uses BN_copy if
1151 * a similar test returns true).
1152 */
1153 /*
1154 * We can use BN_mod and do not need BN_nnmod because our accumulator is
1155 * never negative (the result of BN_mod does not depend on the sign of
1156 * the modulus).
1157 */
1158#define BN_TO_MONTGOMERY_WORD(r, w, mont)(BN_set_word(r, (w)) && BN_to_montgomery(r, r, (mont)
, ctx))
\
1159 (BN_set_word(r, (w)) && BN_to_montgomery(r, r, (mont), ctx))
1160
1161 if (BN_get_flags(p, BN_FLG_CONSTTIME0x04) != 0
1162 || BN_get_flags(m, BN_FLG_CONSTTIME0x04) != 0) {
1163 /* BN_FLG_CONSTTIME only supported by BN_mod_exp_mont() */
1164 ERR_raise(ERR_LIB_BN, ERR_R_SHOULD_NOT_HAVE_BEEN_CALLED)(ERR_new(), ERR_set_debug("../deps/openssl/openssl/crypto/bn/bn_exp.c"
,1164,__func__), ERR_set_error)((3),((257|((0x1 << 18L)
|(0x2 << 18L)))),((void*)0))
;
1165 return 0;
1166 }
1167
1168 bn_check_top(p);
1169 bn_check_top(m);
1170
1171 if (!BN_is_odd(m)) {
1172 ERR_raise(ERR_LIB_BN, BN_R_CALLED_WITH_EVEN_MODULUS)(ERR_new(), ERR_set_debug("../deps/openssl/openssl/crypto/bn/bn_exp.c"
,1172,__func__), ERR_set_error)((3),(102),((void*)0))
;
1173 return 0;
1174 }
1175 if (m->top == 1)
1176 a %= m->d[0]; /* make sure that 'a' is reduced */
1177
1178 bits = BN_num_bits(p);
1179 if (bits == 0) {
1180 /* x**0 mod 1, or x**0 mod -1 is still zero. */
1181 if (BN_abs_is_word(m, 1)) {
1182 ret = 1;
1183 BN_zero(rr)BN_zero_ex(rr);
1184 } else {
1185 ret = BN_one(rr)(BN_set_word((rr),1));
1186 }
1187 return ret;
1188 }
1189 if (a == 0) {
1190 BN_zero(rr)BN_zero_ex(rr);
1191 ret = 1;
1192 return ret;
1193 }
1194
1195 BN_CTX_start(ctx);
1196 r = BN_CTX_get(ctx);
1197 t = BN_CTX_get(ctx);
1198 if (t == NULL((void*)0))
1199 goto err;
1200
1201 if (in_mont != NULL((void*)0))
1202 mont = in_mont;
1203 else {
1204 if ((mont = BN_MONT_CTX_new()) == NULL((void*)0))
1205 goto err;
1206 if (!BN_MONT_CTX_set(mont, m, ctx))
1207 goto err;
1208 }
1209
1210 r_is_one = 1; /* except for Montgomery factor */
1211
1212 /* bits-1 >= 0 */
1213
1214 /* The result is accumulated in the product r*w. */
1215 w = a; /* bit 'bits-1' of 'p' is always set */
1216 for (b = bits - 2; b >= 0; b--) {
1217 /* First, square r*w. */
1218 next_w = w * w;
1219 if ((next_w / w) != w) { /* overflow */
1220 if (r_is_one) {
1221 if (!BN_TO_MONTGOMERY_WORD(r, w, mont)(BN_set_word(r, (w)) && BN_to_montgomery(r, r, (mont)
, ctx))
)
1222 goto err;
1223 r_is_one = 0;
1224 } else {
1225 if (!BN_MOD_MUL_WORD(r, w, m)(BN_mul_word(r, (w)) && ( (BN_div(((void*)0),(t),(r),
(m),(ctx)) && (swap_tmp = r, r = t, t = swap_tmp, 1))
))
)
1226 goto err;
1227 }
1228 next_w = 1;
1229 }
1230 w = next_w;
1231 if (!r_is_one) {
1232 if (!BN_mod_mul_montgomery(r, r, r, mont, ctx))
1233 goto err;
1234 }
1235
1236 /* Second, multiply r*w by 'a' if exponent bit is set. */
1237 if (BN_is_bit_set(p, b)) {
1238 next_w = w * a;
1239 if ((next_w / a) != w) { /* overflow */
1240 if (r_is_one) {
1241 if (!BN_TO_MONTGOMERY_WORD(r, w, mont)(BN_set_word(r, (w)) && BN_to_montgomery(r, r, (mont)
, ctx))
)
1242 goto err;
1243 r_is_one = 0;
1244 } else {
1245 if (!BN_MOD_MUL_WORD(r, w, m)(BN_mul_word(r, (w)) && ( (BN_div(((void*)0),(t),(r),
(m),(ctx)) && (swap_tmp = r, r = t, t = swap_tmp, 1))
))
)
1246 goto err;
1247 }
1248 next_w = a;
1249 }
1250 w = next_w;
1251 }
1252 }
1253
1254 /* Finally, set r:=r*w. */
1255 if (w != 1) {
1256 if (r_is_one) {
1257 if (!BN_TO_MONTGOMERY_WORD(r, w, mont)(BN_set_word(r, (w)) && BN_to_montgomery(r, r, (mont)
, ctx))
)
1258 goto err;
1259 r_is_one = 0;
1260 } else {
1261 if (!BN_MOD_MUL_WORD(r, w, m)(BN_mul_word(r, (w)) && ( (BN_div(((void*)0),(t),(r),
(m),(ctx)) && (swap_tmp = r, r = t, t = swap_tmp, 1))
))
)
1262 goto err;
1263 }
1264 }
1265
1266 if (r_is_one) { /* can happen only if a == 1 */
1267 if (!BN_one(rr)(BN_set_word((rr),1)))
1268 goto err;
1269 } else {
1270 if (!BN_from_montgomery(rr, r, mont, ctx))
1271 goto err;
1272 }
1273 ret = 1;
1274 err:
1275 if (in_mont == NULL((void*)0))
1276 BN_MONT_CTX_free(mont);
1277 BN_CTX_end(ctx);
1278 bn_check_top(rr);
1279 return ret;
1280}
1281
1282/* The old fallback, simple version :-) */
1283int BN_mod_exp_simple(BIGNUM *r, const BIGNUM *a, const BIGNUM *p,
1284 const BIGNUM *m, BN_CTX *ctx)
1285{
1286 int i, j, bits, ret = 0, wstart, wend, window, wvalue;
1287 int start = 1;
1288 BIGNUM *d;
1289 /* Table of variables obtained from 'ctx' */
1290 BIGNUM *val[TABLE_SIZE32];
1291
1292 if (BN_get_flags(p, BN_FLG_CONSTTIME0x04) != 0
1293 || BN_get_flags(a, BN_FLG_CONSTTIME0x04) != 0
1294 || BN_get_flags(m, BN_FLG_CONSTTIME0x04) != 0) {
1295 /* BN_FLG_CONSTTIME only supported by BN_mod_exp_mont() */
1296 ERR_raise(ERR_LIB_BN, ERR_R_SHOULD_NOT_HAVE_BEEN_CALLED)(ERR_new(), ERR_set_debug("../deps/openssl/openssl/crypto/bn/bn_exp.c"
,1296,__func__), ERR_set_error)((3),((257|((0x1 << 18L)
|(0x2 << 18L)))),((void*)0))
;
1297 return 0;
1298 }
1299
1300 bits = BN_num_bits(p);
1301 if (bits == 0) {
1302 /* x**0 mod 1, or x**0 mod -1 is still zero. */
1303 if (BN_abs_is_word(m, 1)) {
1304 ret = 1;
1305 BN_zero(r)BN_zero_ex(r);
1306 } else {
1307 ret = BN_one(r)(BN_set_word((r),1));
1308 }
1309 return ret;
1310 }
1311
1312 BN_CTX_start(ctx);
1313 d = BN_CTX_get(ctx);
1314 val[0] = BN_CTX_get(ctx);
1315 if (val[0] == NULL((void*)0))
1316 goto err;
1317
1318 if (!BN_nnmod(val[0], a, m, ctx))
1319 goto err; /* 1 */
1320 if (BN_is_zero(val[0])) {
1321 BN_zero(r)BN_zero_ex(r);
1322 ret = 1;
1323 goto err;
1324 }
1325
1326 window = BN_window_bits_for_exponent_size(bits)((bits) > 671 ? 6 : (bits) > 239 ? 5 : (bits) > 79 ?
4 : (bits) > 23 ? 3 : 1)
;
1327 if (window > 1) {
1328 if (!BN_mod_mul(d, val[0], val[0], m, ctx))
1329 goto err; /* 2 */
1330 j = 1 << (window - 1);
1331 for (i = 1; i < j; i++) {
1332 if (((val[i] = BN_CTX_get(ctx)) == NULL((void*)0)) ||
1333 !BN_mod_mul(val[i], val[i - 1], d, m, ctx))
1334 goto err;
1335 }
1336 }
1337
1338 start = 1; /* This is used to avoid multiplication etc
1339 * when there is only the value '1' in the
1340 * buffer. */
1341 wvalue = 0; /* The 'value' of the window */
1342 wstart = bits - 1; /* The top bit of the window */
1343 wend = 0; /* The bottom bit of the window */
1344
1345 if (!BN_one(r)(BN_set_word((r),1)))
1346 goto err;
1347
1348 for (;;) {
1349 if (BN_is_bit_set(p, wstart) == 0) {
1350 if (!start)
1351 if (!BN_mod_mul(r, r, r, m, ctx))
1352 goto err;
1353 if (wstart == 0)
1354 break;
1355 wstart--;
1356 continue;
1357 }
1358 /*
1359 * We now have wstart on a 'set' bit, we now need to work out how bit
1360 * a window to do. To do this we need to scan forward until the last
1361 * set bit before the end of the window
1362 */
1363 wvalue = 1;
1364 wend = 0;
1365 for (i = 1; i < window; i++) {
1366 if (wstart - i < 0)
1367 break;
1368 if (BN_is_bit_set(p, wstart - i)) {
1369 wvalue <<= (i - wend);
1370 wvalue |= 1;
1371 wend = i;
1372 }
1373 }
1374
1375 /* wend is the size of the current window */
1376 j = wend + 1;
1377 /* add the 'bytes above' */
1378 if (!start)
1379 for (i = 0; i < j; i++) {
1380 if (!BN_mod_mul(r, r, r, m, ctx))
1381 goto err;
1382 }
1383
1384 /* wvalue will be an odd number < 2^window */
1385 if (!BN_mod_mul(r, r, val[wvalue >> 1], m, ctx))
1386 goto err;
1387
1388 /* move the 'window' down further */
1389 wstart -= wend + 1;
1390 wvalue = 0;
1391 start = 0;
1392 if (wstart < 0)
1393 break;
1394 }
1395 ret = 1;
1396 err:
1397 BN_CTX_end(ctx);
1398 bn_check_top(r);
1399 return ret;
1400}
1401
1402/*
1403 * This is a variant of modular exponentiation optimization that does
1404 * parallel 2-primes exponentiation using 256-bit (AVX512VL) AVX512_IFMA ISA
1405 * in 52-bit binary redundant representation.
1406 * If such instructions are not available, or input data size is not supported,
1407 * it falls back to two BN_mod_exp_mont_consttime() calls.
1408 */
1409int BN_mod_exp_mont_consttime_x2(BIGNUM *rr1, const BIGNUM *a1, const BIGNUM *p1,
1410 const BIGNUM *m1, BN_MONT_CTX *in_mont1,
1411 BIGNUM *rr2, const BIGNUM *a2, const BIGNUM *p2,
1412 const BIGNUM *m2, BN_MONT_CTX *in_mont2,
1413 BN_CTX *ctx)
1414{
1415 int ret = 0;
1416
1417#ifdef RSAZ_ENABLED
1418 BN_MONT_CTX *mont1 = NULL((void*)0);
1419 BN_MONT_CTX *mont2 = NULL((void*)0);
1420
1421 if (ossl_rsaz_avx512ifma_eligible() &&
1422 ((a1->top == 16) && (p1->top == 16) && (BN_num_bits(m1) == 1024) &&
1423 (a2->top == 16) && (p2->top == 16) && (BN_num_bits(m2) == 1024))) {
1424
1425 if (bn_wexpand(rr1, 16) == NULL((void*)0))
1426 goto err;
1427 if (bn_wexpand(rr2, 16) == NULL((void*)0))
1428 goto err;
1429
1430 /* Ensure that montgomery contexts are initialized */
1431 if (in_mont1 != NULL((void*)0)) {
1432 mont1 = in_mont1;
1433 } else {
1434 if ((mont1 = BN_MONT_CTX_new()) == NULL((void*)0))
1435 goto err;
1436 if (!BN_MONT_CTX_set(mont1, m1, ctx))
1437 goto err;
1438 }
1439 if (in_mont2 != NULL((void*)0)) {
1440 mont2 = in_mont2;
1441 } else {
1442 if ((mont2 = BN_MONT_CTX_new()) == NULL((void*)0))
1443 goto err;
1444 if (!BN_MONT_CTX_set(mont2, m2, ctx))
1445 goto err;
1446 }
1447
1448 ret = ossl_rsaz_mod_exp_avx512_x2(rr1->d, a1->d, p1->d, m1->d,
1449 mont1->RR.d, mont1->n0[0],
1450 rr2->d, a2->d, p2->d, m2->d,
1451 mont2->RR.d, mont2->n0[0],
1452 1024 /* factor bit size */);
1453
1454 rr1->top = 16;
1455 rr1->neg = 0;
1456 bn_correct_top(rr1);
1457 bn_check_top(rr1);
1458
1459 rr2->top = 16;
1460 rr2->neg = 0;
1461 bn_correct_top(rr2);
1462 bn_check_top(rr2);
1463
1464 goto err;
1465 }
1466#endif
1467
1468 /* rr1 = a1^p1 mod m1 */
1469 ret = BN_mod_exp_mont_consttime(rr1, a1, p1, m1, ctx, in_mont1);
1470 /* rr2 = a2^p2 mod m2 */
1471 ret &= BN_mod_exp_mont_consttime(rr2, a2, p2, m2, ctx, in_mont2);
1472
1473#ifdef RSAZ_ENABLED
1474err:
1475 if (in_mont2 == NULL((void*)0))
1476 BN_MONT_CTX_free(mont2);
1477 if (in_mont1 == NULL((void*)0))
1478 BN_MONT_CTX_free(mont1);
1479#endif
1480
1481 return ret;
1482}