1 | /* mpicoder.c - Coder for the external representation of MPIs |
2 | * Copyright (C) 1998, 1999 Free Software Foundation, Inc. |
3 | * |
4 | * This file is part of GnuPG. |
5 | * |
6 | * GnuPG is free software; you can redistribute it and/or modify |
7 | * it under the terms of the GNU General Public License as published by |
8 | * the Free Software Foundation; either version 2 of the License, or |
9 | * (at your option) any later version. |
10 | * |
11 | * GnuPG is distributed in the hope that it will be useful, |
12 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
13 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
14 | * GNU General Public License for more details. |
15 | * |
16 | * You should have received a copy of the GNU General Public License |
17 | * along with this program; if not, write to the Free Software |
18 | * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA |
19 | */ |
20 | |
21 | #include <linux/bitops.h> |
22 | #include <linux/count_zeros.h> |
23 | #include <linux/byteorder/generic.h> |
24 | #include <linux/scatterlist.h> |
25 | #include <linux/string.h> |
26 | #include "mpi-internal.h" |
27 | |
28 | #define MAX_EXTERN_SCAN_BYTES (16*1024*1024) |
29 | #define MAX_EXTERN_MPI_BITS 16384 |
30 | |
31 | /** |
32 | * mpi_read_raw_data - Read a raw byte stream as a positive integer |
33 | * @xbuffer: The data to read |
34 | * @nbytes: The amount of data to read |
35 | */ |
36 | MPI mpi_read_raw_data(const void *xbuffer, size_t nbytes) |
37 | { |
38 | const uint8_t *buffer = xbuffer; |
39 | int i, j; |
40 | unsigned nbits, nlimbs; |
41 | mpi_limb_t a; |
42 | MPI val = NULL; |
43 | |
44 | while (nbytes > 0 && buffer[0] == 0) { |
45 | buffer++; |
46 | nbytes--; |
47 | } |
48 | |
49 | nbits = nbytes * 8; |
50 | if (nbits > MAX_EXTERN_MPI_BITS) { |
51 | pr_info("MPI: mpi too large (%u bits)\n" , nbits); |
52 | return NULL; |
53 | } |
54 | if (nbytes > 0) |
55 | nbits -= count_leading_zeros(x: buffer[0]) - (BITS_PER_LONG - 8); |
56 | |
57 | nlimbs = DIV_ROUND_UP(nbytes, BYTES_PER_MPI_LIMB); |
58 | val = mpi_alloc(nlimbs); |
59 | if (!val) |
60 | return NULL; |
61 | val->nbits = nbits; |
62 | val->sign = 0; |
63 | val->nlimbs = nlimbs; |
64 | |
65 | if (nbytes > 0) { |
66 | i = BYTES_PER_MPI_LIMB - nbytes % BYTES_PER_MPI_LIMB; |
67 | i %= BYTES_PER_MPI_LIMB; |
68 | for (j = nlimbs; j > 0; j--) { |
69 | a = 0; |
70 | for (; i < BYTES_PER_MPI_LIMB; i++) { |
71 | a <<= 8; |
72 | a |= *buffer++; |
73 | } |
74 | i = 0; |
75 | val->d[j - 1] = a; |
76 | } |
77 | } |
78 | return val; |
79 | } |
80 | EXPORT_SYMBOL_GPL(mpi_read_raw_data); |
81 | |
82 | MPI mpi_read_from_buffer(const void *xbuffer, unsigned *ret_nread) |
83 | { |
84 | const uint8_t *buffer = xbuffer; |
85 | unsigned int nbits, nbytes; |
86 | MPI val; |
87 | |
88 | if (*ret_nread < 2) |
89 | return ERR_PTR(error: -EINVAL); |
90 | nbits = buffer[0] << 8 | buffer[1]; |
91 | |
92 | if (nbits > MAX_EXTERN_MPI_BITS) { |
93 | pr_info("MPI: mpi too large (%u bits)\n" , nbits); |
94 | return ERR_PTR(error: -EINVAL); |
95 | } |
96 | |
97 | nbytes = DIV_ROUND_UP(nbits, 8); |
98 | if (nbytes + 2 > *ret_nread) { |
99 | pr_info("MPI: mpi larger than buffer nbytes=%u ret_nread=%u\n" , |
100 | nbytes, *ret_nread); |
101 | return ERR_PTR(error: -EINVAL); |
102 | } |
103 | |
104 | val = mpi_read_raw_data(buffer + 2, nbytes); |
105 | if (!val) |
106 | return ERR_PTR(error: -ENOMEM); |
107 | |
108 | *ret_nread = nbytes + 2; |
109 | return val; |
110 | } |
111 | EXPORT_SYMBOL_GPL(mpi_read_from_buffer); |
112 | |
113 | /**************** |
114 | * Fill the mpi VAL from the hex string in STR. |
115 | */ |
116 | int mpi_fromstr(MPI val, const char *str) |
117 | { |
118 | int sign = 0; |
119 | int prepend_zero = 0; |
120 | int i, j, c, c1, c2; |
121 | unsigned int nbits, nbytes, nlimbs; |
122 | mpi_limb_t a; |
123 | |
124 | if (*str == '-') { |
125 | sign = 1; |
126 | str++; |
127 | } |
128 | |
129 | /* Skip optional hex prefix. */ |
130 | if (*str == '0' && str[1] == 'x') |
131 | str += 2; |
132 | |
133 | nbits = strlen(str); |
134 | if (nbits > MAX_EXTERN_SCAN_BYTES) { |
135 | mpi_clear(a: val); |
136 | return -EINVAL; |
137 | } |
138 | nbits *= 4; |
139 | if ((nbits % 8)) |
140 | prepend_zero = 1; |
141 | |
142 | nbytes = (nbits+7) / 8; |
143 | nlimbs = (nbytes+BYTES_PER_MPI_LIMB-1) / BYTES_PER_MPI_LIMB; |
144 | |
145 | if (val->alloced < nlimbs) |
146 | mpi_resize(a: val, nlimbs); |
147 | |
148 | i = BYTES_PER_MPI_LIMB - (nbytes % BYTES_PER_MPI_LIMB); |
149 | i %= BYTES_PER_MPI_LIMB; |
150 | j = val->nlimbs = nlimbs; |
151 | val->sign = sign; |
152 | for (; j > 0; j--) { |
153 | a = 0; |
154 | for (; i < BYTES_PER_MPI_LIMB; i++) { |
155 | if (prepend_zero) { |
156 | c1 = '0'; |
157 | prepend_zero = 0; |
158 | } else |
159 | c1 = *str++; |
160 | |
161 | if (!c1) { |
162 | mpi_clear(a: val); |
163 | return -EINVAL; |
164 | } |
165 | c2 = *str++; |
166 | if (!c2) { |
167 | mpi_clear(a: val); |
168 | return -EINVAL; |
169 | } |
170 | if (c1 >= '0' && c1 <= '9') |
171 | c = c1 - '0'; |
172 | else if (c1 >= 'a' && c1 <= 'f') |
173 | c = c1 - 'a' + 10; |
174 | else if (c1 >= 'A' && c1 <= 'F') |
175 | c = c1 - 'A' + 10; |
176 | else { |
177 | mpi_clear(a: val); |
178 | return -EINVAL; |
179 | } |
180 | c <<= 4; |
181 | if (c2 >= '0' && c2 <= '9') |
182 | c |= c2 - '0'; |
183 | else if (c2 >= 'a' && c2 <= 'f') |
184 | c |= c2 - 'a' + 10; |
185 | else if (c2 >= 'A' && c2 <= 'F') |
186 | c |= c2 - 'A' + 10; |
187 | else { |
188 | mpi_clear(a: val); |
189 | return -EINVAL; |
190 | } |
191 | a <<= 8; |
192 | a |= c; |
193 | } |
194 | i = 0; |
195 | val->d[j-1] = a; |
196 | } |
197 | |
198 | return 0; |
199 | } |
200 | EXPORT_SYMBOL_GPL(mpi_fromstr); |
201 | |
202 | MPI mpi_scanval(const char *string) |
203 | { |
204 | MPI a; |
205 | |
206 | a = mpi_alloc(nlimbs: 0); |
207 | if (!a) |
208 | return NULL; |
209 | |
210 | if (mpi_fromstr(a, string)) { |
211 | mpi_free(a); |
212 | return NULL; |
213 | } |
214 | mpi_normalize(a); |
215 | return a; |
216 | } |
217 | EXPORT_SYMBOL_GPL(mpi_scanval); |
218 | |
219 | static int count_lzeros(MPI a) |
220 | { |
221 | mpi_limb_t alimb; |
222 | int i, lzeros = 0; |
223 | |
224 | for (i = a->nlimbs - 1; i >= 0; i--) { |
225 | alimb = a->d[i]; |
226 | if (alimb == 0) { |
227 | lzeros += sizeof(mpi_limb_t); |
228 | } else { |
229 | lzeros += count_leading_zeros(x: alimb) / 8; |
230 | break; |
231 | } |
232 | } |
233 | return lzeros; |
234 | } |
235 | |
236 | /** |
237 | * mpi_read_buffer() - read MPI to a buffer provided by user (msb first) |
238 | * |
239 | * @a: a multi precision integer |
240 | * @buf: buffer to which the output will be written to. Needs to be at |
241 | * least mpi_get_size(a) long. |
242 | * @buf_len: size of the buf. |
243 | * @nbytes: receives the actual length of the data written on success and |
244 | * the data to-be-written on -EOVERFLOW in case buf_len was too |
245 | * small. |
246 | * @sign: if not NULL, it will be set to the sign of a. |
247 | * |
248 | * Return: 0 on success or error code in case of error |
249 | */ |
250 | int mpi_read_buffer(MPI a, uint8_t *buf, unsigned buf_len, unsigned *nbytes, |
251 | int *sign) |
252 | { |
253 | uint8_t *p; |
254 | #if BYTES_PER_MPI_LIMB == 4 |
255 | __be32 alimb; |
256 | #elif BYTES_PER_MPI_LIMB == 8 |
257 | __be64 alimb; |
258 | #else |
259 | #error please implement for this limb size. |
260 | #endif |
261 | unsigned int n = mpi_get_size(a); |
262 | int i, lzeros; |
263 | |
264 | if (!buf || !nbytes) |
265 | return -EINVAL; |
266 | |
267 | if (sign) |
268 | *sign = a->sign; |
269 | |
270 | lzeros = count_lzeros(a); |
271 | |
272 | if (buf_len < n - lzeros) { |
273 | *nbytes = n - lzeros; |
274 | return -EOVERFLOW; |
275 | } |
276 | |
277 | p = buf; |
278 | *nbytes = n - lzeros; |
279 | |
280 | for (i = a->nlimbs - 1 - lzeros / BYTES_PER_MPI_LIMB, |
281 | lzeros %= BYTES_PER_MPI_LIMB; |
282 | i >= 0; i--) { |
283 | #if BYTES_PER_MPI_LIMB == 4 |
284 | alimb = cpu_to_be32(a->d[i]); |
285 | #elif BYTES_PER_MPI_LIMB == 8 |
286 | alimb = cpu_to_be64(a->d[i]); |
287 | #else |
288 | #error please implement for this limb size. |
289 | #endif |
290 | memcpy(p, (u8 *)&alimb + lzeros, BYTES_PER_MPI_LIMB - lzeros); |
291 | p += BYTES_PER_MPI_LIMB - lzeros; |
292 | lzeros = 0; |
293 | } |
294 | return 0; |
295 | } |
296 | EXPORT_SYMBOL_GPL(mpi_read_buffer); |
297 | |
298 | /* |
299 | * mpi_get_buffer() - Returns an allocated buffer with the MPI (msb first). |
300 | * Caller must free the return string. |
301 | * This function does return a 0 byte buffer with nbytes set to zero if the |
302 | * value of A is zero. |
303 | * |
304 | * @a: a multi precision integer. |
305 | * @nbytes: receives the length of this buffer. |
306 | * @sign: if not NULL, it will be set to the sign of the a. |
307 | * |
308 | * Return: Pointer to MPI buffer or NULL on error |
309 | */ |
310 | void *mpi_get_buffer(MPI a, unsigned *nbytes, int *sign) |
311 | { |
312 | uint8_t *buf; |
313 | unsigned int n; |
314 | int ret; |
315 | |
316 | if (!nbytes) |
317 | return NULL; |
318 | |
319 | n = mpi_get_size(a); |
320 | |
321 | if (!n) |
322 | n++; |
323 | |
324 | buf = kmalloc(size: n, GFP_KERNEL); |
325 | |
326 | if (!buf) |
327 | return NULL; |
328 | |
329 | ret = mpi_read_buffer(a, buf, n, nbytes, sign); |
330 | |
331 | if (ret) { |
332 | kfree(objp: buf); |
333 | return NULL; |
334 | } |
335 | return buf; |
336 | } |
337 | EXPORT_SYMBOL_GPL(mpi_get_buffer); |
338 | |
339 | /** |
340 | * mpi_write_to_sgl() - Funnction exports MPI to an sgl (msb first) |
341 | * |
342 | * This function works in the same way as the mpi_read_buffer, but it |
343 | * takes an sgl instead of u8 * buf. |
344 | * |
345 | * @a: a multi precision integer |
346 | * @sgl: scatterlist to write to. Needs to be at least |
347 | * mpi_get_size(a) long. |
348 | * @nbytes: the number of bytes to write. Leading bytes will be |
349 | * filled with zero. |
350 | * @sign: if not NULL, it will be set to the sign of a. |
351 | * |
352 | * Return: 0 on success or error code in case of error |
353 | */ |
354 | int mpi_write_to_sgl(MPI a, struct scatterlist *sgl, unsigned nbytes, |
355 | int *sign) |
356 | { |
357 | u8 *p, *p2; |
358 | #if BYTES_PER_MPI_LIMB == 4 |
359 | __be32 alimb; |
360 | #elif BYTES_PER_MPI_LIMB == 8 |
361 | __be64 alimb; |
362 | #else |
363 | #error please implement for this limb size. |
364 | #endif |
365 | unsigned int n = mpi_get_size(a); |
366 | struct sg_mapping_iter miter; |
367 | int i, x, buf_len; |
368 | int nents; |
369 | |
370 | if (sign) |
371 | *sign = a->sign; |
372 | |
373 | if (nbytes < n) |
374 | return -EOVERFLOW; |
375 | |
376 | nents = sg_nents_for_len(sg: sgl, len: nbytes); |
377 | if (nents < 0) |
378 | return -EINVAL; |
379 | |
380 | sg_miter_start(miter: &miter, sgl, nents, SG_MITER_ATOMIC | SG_MITER_TO_SG); |
381 | sg_miter_next(miter: &miter); |
382 | buf_len = miter.length; |
383 | p2 = miter.addr; |
384 | |
385 | while (nbytes > n) { |
386 | i = min_t(unsigned, nbytes - n, buf_len); |
387 | memset(p2, 0, i); |
388 | p2 += i; |
389 | nbytes -= i; |
390 | |
391 | buf_len -= i; |
392 | if (!buf_len) { |
393 | sg_miter_next(miter: &miter); |
394 | buf_len = miter.length; |
395 | p2 = miter.addr; |
396 | } |
397 | } |
398 | |
399 | for (i = a->nlimbs - 1; i >= 0; i--) { |
400 | #if BYTES_PER_MPI_LIMB == 4 |
401 | alimb = a->d[i] ? cpu_to_be32(a->d[i]) : 0; |
402 | #elif BYTES_PER_MPI_LIMB == 8 |
403 | alimb = a->d[i] ? cpu_to_be64(a->d[i]) : 0; |
404 | #else |
405 | #error please implement for this limb size. |
406 | #endif |
407 | p = (u8 *)&alimb; |
408 | |
409 | for (x = 0; x < sizeof(alimb); x++) { |
410 | *p2++ = *p++; |
411 | if (!--buf_len) { |
412 | sg_miter_next(miter: &miter); |
413 | buf_len = miter.length; |
414 | p2 = miter.addr; |
415 | } |
416 | } |
417 | } |
418 | |
419 | sg_miter_stop(miter: &miter); |
420 | return 0; |
421 | } |
422 | EXPORT_SYMBOL_GPL(mpi_write_to_sgl); |
423 | |
424 | /* |
425 | * mpi_read_raw_from_sgl() - Function allocates an MPI and populates it with |
426 | * data from the sgl |
427 | * |
428 | * This function works in the same way as the mpi_read_raw_data, but it |
429 | * takes an sgl instead of void * buffer. i.e. it allocates |
430 | * a new MPI and reads the content of the sgl to the MPI. |
431 | * |
432 | * @sgl: scatterlist to read from |
433 | * @nbytes: number of bytes to read |
434 | * |
435 | * Return: Pointer to a new MPI or NULL on error |
436 | */ |
437 | MPI mpi_read_raw_from_sgl(struct scatterlist *sgl, unsigned int nbytes) |
438 | { |
439 | struct sg_mapping_iter miter; |
440 | unsigned int nbits, nlimbs; |
441 | int x, j, z, lzeros, ents; |
442 | unsigned int len; |
443 | const u8 *buff; |
444 | mpi_limb_t a; |
445 | MPI val = NULL; |
446 | |
447 | ents = sg_nents_for_len(sg: sgl, len: nbytes); |
448 | if (ents < 0) |
449 | return NULL; |
450 | |
451 | sg_miter_start(miter: &miter, sgl, nents: ents, SG_MITER_ATOMIC | SG_MITER_FROM_SG); |
452 | |
453 | lzeros = 0; |
454 | len = 0; |
455 | while (nbytes > 0) { |
456 | while (len && !*buff) { |
457 | lzeros++; |
458 | len--; |
459 | buff++; |
460 | } |
461 | |
462 | if (len && *buff) |
463 | break; |
464 | |
465 | sg_miter_next(miter: &miter); |
466 | buff = miter.addr; |
467 | len = miter.length; |
468 | |
469 | nbytes -= lzeros; |
470 | lzeros = 0; |
471 | } |
472 | |
473 | miter.consumed = lzeros; |
474 | |
475 | nbytes -= lzeros; |
476 | nbits = nbytes * 8; |
477 | if (nbits > MAX_EXTERN_MPI_BITS) { |
478 | sg_miter_stop(miter: &miter); |
479 | pr_info("MPI: mpi too large (%u bits)\n" , nbits); |
480 | return NULL; |
481 | } |
482 | |
483 | if (nbytes > 0) |
484 | nbits -= count_leading_zeros(x: *buff) - (BITS_PER_LONG - 8); |
485 | |
486 | sg_miter_stop(miter: &miter); |
487 | |
488 | nlimbs = DIV_ROUND_UP(nbytes, BYTES_PER_MPI_LIMB); |
489 | val = mpi_alloc(nlimbs); |
490 | if (!val) |
491 | return NULL; |
492 | |
493 | val->nbits = nbits; |
494 | val->sign = 0; |
495 | val->nlimbs = nlimbs; |
496 | |
497 | if (nbytes == 0) |
498 | return val; |
499 | |
500 | j = nlimbs - 1; |
501 | a = 0; |
502 | z = BYTES_PER_MPI_LIMB - nbytes % BYTES_PER_MPI_LIMB; |
503 | z %= BYTES_PER_MPI_LIMB; |
504 | |
505 | while (sg_miter_next(miter: &miter)) { |
506 | buff = miter.addr; |
507 | len = min_t(unsigned, miter.length, nbytes); |
508 | nbytes -= len; |
509 | |
510 | for (x = 0; x < len; x++) { |
511 | a <<= 8; |
512 | a |= *buff++; |
513 | if (((z + x + 1) % BYTES_PER_MPI_LIMB) == 0) { |
514 | val->d[j--] = a; |
515 | a = 0; |
516 | } |
517 | } |
518 | z += x; |
519 | } |
520 | |
521 | return val; |
522 | } |
523 | EXPORT_SYMBOL_GPL(mpi_read_raw_from_sgl); |
524 | |
525 | /* Perform a two's complement operation on buffer P of size N bytes. */ |
526 | static void twocompl(unsigned char *p, unsigned int n) |
527 | { |
528 | int i; |
529 | |
530 | for (i = n-1; i >= 0 && !p[i]; i--) |
531 | ; |
532 | if (i >= 0) { |
533 | if ((p[i] & 0x01)) |
534 | p[i] = (((p[i] ^ 0xfe) | 0x01) & 0xff); |
535 | else if ((p[i] & 0x02)) |
536 | p[i] = (((p[i] ^ 0xfc) | 0x02) & 0xfe); |
537 | else if ((p[i] & 0x04)) |
538 | p[i] = (((p[i] ^ 0xf8) | 0x04) & 0xfc); |
539 | else if ((p[i] & 0x08)) |
540 | p[i] = (((p[i] ^ 0xf0) | 0x08) & 0xf8); |
541 | else if ((p[i] & 0x10)) |
542 | p[i] = (((p[i] ^ 0xe0) | 0x10) & 0xf0); |
543 | else if ((p[i] & 0x20)) |
544 | p[i] = (((p[i] ^ 0xc0) | 0x20) & 0xe0); |
545 | else if ((p[i] & 0x40)) |
546 | p[i] = (((p[i] ^ 0x80) | 0x40) & 0xc0); |
547 | else |
548 | p[i] = 0x80; |
549 | |
550 | for (i--; i >= 0; i--) |
551 | p[i] ^= 0xff; |
552 | } |
553 | } |
554 | |
555 | int mpi_print(enum gcry_mpi_format format, unsigned char *buffer, |
556 | size_t buflen, size_t *nwritten, MPI a) |
557 | { |
558 | unsigned int nbits = mpi_get_nbits(a); |
559 | size_t len; |
560 | size_t dummy_nwritten; |
561 | int negative; |
562 | |
563 | if (!nwritten) |
564 | nwritten = &dummy_nwritten; |
565 | |
566 | /* Libgcrypt does no always care to set clear the sign if the value |
567 | * is 0. For printing this is a bit of a surprise, in particular |
568 | * because if some of the formats don't support negative numbers but |
569 | * should be able to print a zero. Thus we need this extra test |
570 | * for a negative number. |
571 | */ |
572 | if (a->sign && mpi_cmp_ui(u: a, v: 0)) |
573 | negative = 1; |
574 | else |
575 | negative = 0; |
576 | |
577 | len = buflen; |
578 | *nwritten = 0; |
579 | if (format == GCRYMPI_FMT_STD) { |
580 | unsigned char *tmp; |
581 | int = 0; |
582 | unsigned int n; |
583 | |
584 | tmp = mpi_get_buffer(a, &n, NULL); |
585 | if (!tmp) |
586 | return -EINVAL; |
587 | |
588 | if (negative) { |
589 | twocompl(p: tmp, n); |
590 | if (!(*tmp & 0x80)) { |
591 | /* Need to extend the sign. */ |
592 | n++; |
593 | extra = 2; |
594 | } |
595 | } else if (n && (*tmp & 0x80)) { |
596 | /* Positive but the high bit of the returned buffer is set. |
597 | * Thus we need to print an extra leading 0x00 so that the |
598 | * output is interpreted as a positive number. |
599 | */ |
600 | n++; |
601 | extra = 1; |
602 | } |
603 | |
604 | if (buffer && n > len) { |
605 | /* The provided buffer is too short. */ |
606 | kfree(objp: tmp); |
607 | return -E2BIG; |
608 | } |
609 | if (buffer) { |
610 | unsigned char *s = buffer; |
611 | |
612 | if (extra == 1) |
613 | *s++ = 0; |
614 | else if (extra) |
615 | *s++ = 0xff; |
616 | memcpy(s, tmp, n-!!extra); |
617 | } |
618 | kfree(objp: tmp); |
619 | *nwritten = n; |
620 | return 0; |
621 | } else if (format == GCRYMPI_FMT_USG) { |
622 | unsigned int n = (nbits + 7)/8; |
623 | |
624 | /* Note: We ignore the sign for this format. */ |
625 | /* FIXME: for performance reasons we should put this into |
626 | * mpi_aprint because we can then use the buffer directly. |
627 | */ |
628 | |
629 | if (buffer && n > len) |
630 | return -E2BIG; |
631 | if (buffer) { |
632 | unsigned char *tmp; |
633 | |
634 | tmp = mpi_get_buffer(a, &n, NULL); |
635 | if (!tmp) |
636 | return -EINVAL; |
637 | memcpy(buffer, tmp, n); |
638 | kfree(objp: tmp); |
639 | } |
640 | *nwritten = n; |
641 | return 0; |
642 | } else if (format == GCRYMPI_FMT_PGP) { |
643 | unsigned int n = (nbits + 7)/8; |
644 | |
645 | /* The PGP format can only handle unsigned integers. */ |
646 | if (negative) |
647 | return -EINVAL; |
648 | |
649 | if (buffer && n+2 > len) |
650 | return -E2BIG; |
651 | |
652 | if (buffer) { |
653 | unsigned char *tmp; |
654 | unsigned char *s = buffer; |
655 | |
656 | s[0] = nbits >> 8; |
657 | s[1] = nbits; |
658 | |
659 | tmp = mpi_get_buffer(a, &n, NULL); |
660 | if (!tmp) |
661 | return -EINVAL; |
662 | memcpy(s+2, tmp, n); |
663 | kfree(objp: tmp); |
664 | } |
665 | *nwritten = n+2; |
666 | return 0; |
667 | } else if (format == GCRYMPI_FMT_SSH) { |
668 | unsigned char *tmp; |
669 | int = 0; |
670 | unsigned int n; |
671 | |
672 | tmp = mpi_get_buffer(a, &n, NULL); |
673 | if (!tmp) |
674 | return -EINVAL; |
675 | |
676 | if (negative) { |
677 | twocompl(p: tmp, n); |
678 | if (!(*tmp & 0x80)) { |
679 | /* Need to extend the sign. */ |
680 | n++; |
681 | extra = 2; |
682 | } |
683 | } else if (n && (*tmp & 0x80)) { |
684 | n++; |
685 | extra = 1; |
686 | } |
687 | |
688 | if (buffer && n+4 > len) { |
689 | kfree(objp: tmp); |
690 | return -E2BIG; |
691 | } |
692 | |
693 | if (buffer) { |
694 | unsigned char *s = buffer; |
695 | |
696 | *s++ = n >> 24; |
697 | *s++ = n >> 16; |
698 | *s++ = n >> 8; |
699 | *s++ = n; |
700 | if (extra == 1) |
701 | *s++ = 0; |
702 | else if (extra) |
703 | *s++ = 0xff; |
704 | memcpy(s, tmp, n-!!extra); |
705 | } |
706 | kfree(objp: tmp); |
707 | *nwritten = 4+n; |
708 | return 0; |
709 | } else if (format == GCRYMPI_FMT_HEX) { |
710 | unsigned char *tmp; |
711 | int i; |
712 | int = 0; |
713 | unsigned int n = 0; |
714 | |
715 | tmp = mpi_get_buffer(a, &n, NULL); |
716 | if (!tmp) |
717 | return -EINVAL; |
718 | if (!n || (*tmp & 0x80)) |
719 | extra = 2; |
720 | |
721 | if (buffer && 2*n + extra + negative + 1 > len) { |
722 | kfree(objp: tmp); |
723 | return -E2BIG; |
724 | } |
725 | if (buffer) { |
726 | unsigned char *s = buffer; |
727 | |
728 | if (negative) |
729 | *s++ = '-'; |
730 | if (extra) { |
731 | *s++ = '0'; |
732 | *s++ = '0'; |
733 | } |
734 | |
735 | for (i = 0; i < n; i++) { |
736 | unsigned int c = tmp[i]; |
737 | |
738 | *s++ = (c >> 4) < 10 ? '0'+(c>>4) : 'A'+(c>>4)-10; |
739 | c &= 15; |
740 | *s++ = c < 10 ? '0'+c : 'A'+c-10; |
741 | } |
742 | *s++ = 0; |
743 | *nwritten = s - buffer; |
744 | } else { |
745 | *nwritten = 2*n + extra + negative + 1; |
746 | } |
747 | kfree(objp: tmp); |
748 | return 0; |
749 | } else |
750 | return -EINVAL; |
751 | } |
752 | EXPORT_SYMBOL_GPL(mpi_print); |
753 | |