+++ /dev/null
-/* mpicoder.c - Coder for the external representation of MPIs
- * Copyright (C) 1998, 1999 Free Software Foundation, Inc.
- *
- * This file is part of GnuPG.
- *
- * GnuPG is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation; either version 2 of the License, or
- * (at your option) any later version.
- *
- * GnuPG is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program; if not, write to the Free Software
- * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
- */
-
-#include <linux/bitops.h>
-#include <linux/count_zeros.h>
-#include <linux/byteorder/generic.h>
-#include <linux/scatterlist.h>
-#include <linux/string.h>
-#include "mpi-internal.h"
-
-#define MAX_EXTERN_SCAN_BYTES (16*1024*1024)
-#define MAX_EXTERN_MPI_BITS 16384
-
-/**
- * mpi_read_raw_data - Read a raw byte stream as a positive integer
- * @xbuffer: The data to read
- * @nbytes: The amount of data to read
- */
-MPI mpi_read_raw_data(const void *xbuffer, size_t nbytes)
-{
- const uint8_t *buffer = xbuffer;
- int i, j;
- unsigned nbits, nlimbs;
- mpi_limb_t a;
- MPI val = NULL;
-
- while (nbytes > 0 && buffer[0] == 0) {
- buffer++;
- nbytes--;
- }
-
- nbits = nbytes * 8;
- if (nbits > MAX_EXTERN_MPI_BITS) {
- pr_info("MPI: mpi too large (%u bits)\n", nbits);
- return NULL;
- }
- if (nbytes > 0)
- nbits -= count_leading_zeros(buffer[0]) - (BITS_PER_LONG - 8);
-
- nlimbs = DIV_ROUND_UP(nbytes, BYTES_PER_MPI_LIMB);
- val = mpi_alloc(nlimbs);
- if (!val)
- return NULL;
- val->nbits = nbits;
- val->sign = 0;
- val->nlimbs = nlimbs;
-
- if (nbytes > 0) {
- i = BYTES_PER_MPI_LIMB - nbytes % BYTES_PER_MPI_LIMB;
- i %= BYTES_PER_MPI_LIMB;
- for (j = nlimbs; j > 0; j--) {
- a = 0;
- for (; i < BYTES_PER_MPI_LIMB; i++) {
- a <<= 8;
- a |= *buffer++;
- }
- i = 0;
- val->d[j - 1] = a;
- }
- }
- return val;
-}
-EXPORT_SYMBOL_GPL(mpi_read_raw_data);
-
-MPI mpi_read_from_buffer(const void *xbuffer, unsigned *ret_nread)
-{
- const uint8_t *buffer = xbuffer;
- unsigned int nbits, nbytes;
- MPI val;
-
- if (*ret_nread < 2)
- return ERR_PTR(-EINVAL);
- nbits = buffer[0] << 8 | buffer[1];
-
- if (nbits > MAX_EXTERN_MPI_BITS) {
- pr_info("MPI: mpi too large (%u bits)\n", nbits);
- return ERR_PTR(-EINVAL);
- }
-
- nbytes = DIV_ROUND_UP(nbits, 8);
- if (nbytes + 2 > *ret_nread) {
- pr_info("MPI: mpi larger than buffer nbytes=%u ret_nread=%u\n",
- nbytes, *ret_nread);
- return ERR_PTR(-EINVAL);
- }
-
- val = mpi_read_raw_data(buffer + 2, nbytes);
- if (!val)
- return ERR_PTR(-ENOMEM);
-
- *ret_nread = nbytes + 2;
- return val;
-}
-EXPORT_SYMBOL_GPL(mpi_read_from_buffer);
-
-/****************
- * Fill the mpi VAL from the hex string in STR.
- */
-int mpi_fromstr(MPI val, const char *str)
-{
- int sign = 0;
- int prepend_zero = 0;
- int i, j, c, c1, c2;
- unsigned int nbits, nbytes, nlimbs;
- mpi_limb_t a;
-
- if (*str == '-') {
- sign = 1;
- str++;
- }
-
- /* Skip optional hex prefix. */
- if (*str == '0' && str[1] == 'x')
- str += 2;
-
- nbits = strlen(str);
- if (nbits > MAX_EXTERN_SCAN_BYTES) {
- mpi_clear(val);
- return -EINVAL;
- }
- nbits *= 4;
- if ((nbits % 8))
- prepend_zero = 1;
-
- nbytes = (nbits+7) / 8;
- nlimbs = (nbytes+BYTES_PER_MPI_LIMB-1) / BYTES_PER_MPI_LIMB;
-
- if (val->alloced < nlimbs)
- mpi_resize(val, nlimbs);
-
- i = BYTES_PER_MPI_LIMB - (nbytes % BYTES_PER_MPI_LIMB);
- i %= BYTES_PER_MPI_LIMB;
- j = val->nlimbs = nlimbs;
- val->sign = sign;
- for (; j > 0; j--) {
- a = 0;
- for (; i < BYTES_PER_MPI_LIMB; i++) {
- if (prepend_zero) {
- c1 = '0';
- prepend_zero = 0;
- } else
- c1 = *str++;
-
- if (!c1) {
- mpi_clear(val);
- return -EINVAL;
- }
- c2 = *str++;
- if (!c2) {
- mpi_clear(val);
- return -EINVAL;
- }
- if (c1 >= '0' && c1 <= '9')
- c = c1 - '0';
- else if (c1 >= 'a' && c1 <= 'f')
- c = c1 - 'a' + 10;
- else if (c1 >= 'A' && c1 <= 'F')
- c = c1 - 'A' + 10;
- else {
- mpi_clear(val);
- return -EINVAL;
- }
- c <<= 4;
- if (c2 >= '0' && c2 <= '9')
- c |= c2 - '0';
- else if (c2 >= 'a' && c2 <= 'f')
- c |= c2 - 'a' + 10;
- else if (c2 >= 'A' && c2 <= 'F')
- c |= c2 - 'A' + 10;
- else {
- mpi_clear(val);
- return -EINVAL;
- }
- a <<= 8;
- a |= c;
- }
- i = 0;
- val->d[j-1] = a;
- }
-
- return 0;
-}
-EXPORT_SYMBOL_GPL(mpi_fromstr);
-
-MPI mpi_scanval(const char *string)
-{
- MPI a;
-
- a = mpi_alloc(0);
- if (!a)
- return NULL;
-
- if (mpi_fromstr(a, string)) {
- mpi_free(a);
- return NULL;
- }
- mpi_normalize(a);
- return a;
-}
-EXPORT_SYMBOL_GPL(mpi_scanval);
-
-static int count_lzeros(MPI a)
-{
- mpi_limb_t alimb;
- int i, lzeros = 0;
-
- for (i = a->nlimbs - 1; i >= 0; i--) {
- alimb = a->d[i];
- if (alimb == 0) {
- lzeros += sizeof(mpi_limb_t);
- } else {
- lzeros += count_leading_zeros(alimb) / 8;
- break;
- }
- }
- return lzeros;
-}
-
-/**
- * mpi_read_buffer() - read MPI to a buffer provided by user (msb first)
- *
- * @a: a multi precision integer
- * @buf: buffer to which the output will be written to. Needs to be at
- * least mpi_get_size(a) long.
- * @buf_len: size of the buf.
- * @nbytes: receives the actual length of the data written on success and
- * the data to-be-written on -EOVERFLOW in case buf_len was too
- * small.
- * @sign: if not NULL, it will be set to the sign of a.
- *
- * Return: 0 on success or error code in case of error
- */
-int mpi_read_buffer(MPI a, uint8_t *buf, unsigned buf_len, unsigned *nbytes,
- int *sign)
-{
- uint8_t *p;
-#if BYTES_PER_MPI_LIMB == 4
- __be32 alimb;
-#elif BYTES_PER_MPI_LIMB == 8
- __be64 alimb;
-#else
-#error please implement for this limb size.
-#endif
- unsigned int n = mpi_get_size(a);
- int i, lzeros;
-
- if (!buf || !nbytes)
- return -EINVAL;
-
- if (sign)
- *sign = a->sign;
-
- lzeros = count_lzeros(a);
-
- if (buf_len < n - lzeros) {
- *nbytes = n - lzeros;
- return -EOVERFLOW;
- }
-
- p = buf;
- *nbytes = n - lzeros;
-
- for (i = a->nlimbs - 1 - lzeros / BYTES_PER_MPI_LIMB,
- lzeros %= BYTES_PER_MPI_LIMB;
- i >= 0; i--) {
-#if BYTES_PER_MPI_LIMB == 4
- alimb = cpu_to_be32(a->d[i]);
-#elif BYTES_PER_MPI_LIMB == 8
- alimb = cpu_to_be64(a->d[i]);
-#else
-#error please implement for this limb size.
-#endif
- memcpy(p, (u8 *)&alimb + lzeros, BYTES_PER_MPI_LIMB - lzeros);
- p += BYTES_PER_MPI_LIMB - lzeros;
- lzeros = 0;
- }
- return 0;
-}
-EXPORT_SYMBOL_GPL(mpi_read_buffer);
-
-/*
- * mpi_get_buffer() - Returns an allocated buffer with the MPI (msb first).
- * Caller must free the return string.
- * This function does return a 0 byte buffer with nbytes set to zero if the
- * value of A is zero.
- *
- * @a: a multi precision integer.
- * @nbytes: receives the length of this buffer.
- * @sign: if not NULL, it will be set to the sign of the a.
- *
- * Return: Pointer to MPI buffer or NULL on error
- */
-void *mpi_get_buffer(MPI a, unsigned *nbytes, int *sign)
-{
- uint8_t *buf;
- unsigned int n;
- int ret;
-
- if (!nbytes)
- return NULL;
-
- n = mpi_get_size(a);
-
- if (!n)
- n++;
-
- buf = kmalloc(n, GFP_KERNEL);
-
- if (!buf)
- return NULL;
-
- ret = mpi_read_buffer(a, buf, n, nbytes, sign);
-
- if (ret) {
- kfree(buf);
- return NULL;
- }
- return buf;
-}
-EXPORT_SYMBOL_GPL(mpi_get_buffer);
-
-/**
- * mpi_write_to_sgl() - Funnction exports MPI to an sgl (msb first)
- *
- * This function works in the same way as the mpi_read_buffer, but it
- * takes an sgl instead of u8 * buf.
- *
- * @a: a multi precision integer
- * @sgl: scatterlist to write to. Needs to be at least
- * mpi_get_size(a) long.
- * @nbytes: the number of bytes to write. Leading bytes will be
- * filled with zero.
- * @sign: if not NULL, it will be set to the sign of a.
- *
- * Return: 0 on success or error code in case of error
- */
-int mpi_write_to_sgl(MPI a, struct scatterlist *sgl, unsigned nbytes,
- int *sign)
-{
- u8 *p, *p2;
-#if BYTES_PER_MPI_LIMB == 4
- __be32 alimb;
-#elif BYTES_PER_MPI_LIMB == 8
- __be64 alimb;
-#else
-#error please implement for this limb size.
-#endif
- unsigned int n = mpi_get_size(a);
- struct sg_mapping_iter miter;
- int i, x, buf_len;
- int nents;
-
- if (sign)
- *sign = a->sign;
-
- if (nbytes < n)
- return -EOVERFLOW;
-
- nents = sg_nents_for_len(sgl, nbytes);
- if (nents < 0)
- return -EINVAL;
-
- sg_miter_start(&miter, sgl, nents, SG_MITER_ATOMIC | SG_MITER_TO_SG);
- sg_miter_next(&miter);
- buf_len = miter.length;
- p2 = miter.addr;
-
- while (nbytes > n) {
- i = min_t(unsigned, nbytes - n, buf_len);
- memset(p2, 0, i);
- p2 += i;
- nbytes -= i;
-
- buf_len -= i;
- if (!buf_len) {
- sg_miter_next(&miter);
- buf_len = miter.length;
- p2 = miter.addr;
- }
- }
-
- for (i = a->nlimbs - 1; i >= 0; i--) {
-#if BYTES_PER_MPI_LIMB == 4
- alimb = a->d[i] ? cpu_to_be32(a->d[i]) : 0;
-#elif BYTES_PER_MPI_LIMB == 8
- alimb = a->d[i] ? cpu_to_be64(a->d[i]) : 0;
-#else
-#error please implement for this limb size.
-#endif
- p = (u8 *)&alimb;
-
- for (x = 0; x < sizeof(alimb); x++) {
- *p2++ = *p++;
- if (!--buf_len) {
- sg_miter_next(&miter);
- buf_len = miter.length;
- p2 = miter.addr;
- }
- }
- }
-
- sg_miter_stop(&miter);
- return 0;
-}
-EXPORT_SYMBOL_GPL(mpi_write_to_sgl);
-
-/*
- * mpi_read_raw_from_sgl() - Function allocates an MPI and populates it with
- * data from the sgl
- *
- * This function works in the same way as the mpi_read_raw_data, but it
- * takes an sgl instead of void * buffer. i.e. it allocates
- * a new MPI and reads the content of the sgl to the MPI.
- *
- * @sgl: scatterlist to read from
- * @nbytes: number of bytes to read
- *
- * Return: Pointer to a new MPI or NULL on error
- */
-MPI mpi_read_raw_from_sgl(struct scatterlist *sgl, unsigned int nbytes)
-{
- struct sg_mapping_iter miter;
- unsigned int nbits, nlimbs;
- int x, j, z, lzeros, ents;
- unsigned int len;
- const u8 *buff;
- mpi_limb_t a;
- MPI val = NULL;
-
- ents = sg_nents_for_len(sgl, nbytes);
- if (ents < 0)
- return NULL;
-
- sg_miter_start(&miter, sgl, ents, SG_MITER_ATOMIC | SG_MITER_FROM_SG);
-
- lzeros = 0;
- len = 0;
- while (nbytes > 0) {
- while (len && !*buff) {
- lzeros++;
- len--;
- buff++;
- }
-
- if (len && *buff)
- break;
-
- sg_miter_next(&miter);
- buff = miter.addr;
- len = miter.length;
-
- nbytes -= lzeros;
- lzeros = 0;
- }
-
- miter.consumed = lzeros;
-
- nbytes -= lzeros;
- nbits = nbytes * 8;
- if (nbits > MAX_EXTERN_MPI_BITS) {
- sg_miter_stop(&miter);
- pr_info("MPI: mpi too large (%u bits)\n", nbits);
- return NULL;
- }
-
- if (nbytes > 0)
- nbits -= count_leading_zeros(*buff) - (BITS_PER_LONG - 8);
-
- sg_miter_stop(&miter);
-
- nlimbs = DIV_ROUND_UP(nbytes, BYTES_PER_MPI_LIMB);
- val = mpi_alloc(nlimbs);
- if (!val)
- return NULL;
-
- val->nbits = nbits;
- val->sign = 0;
- val->nlimbs = nlimbs;
-
- if (nbytes == 0)
- return val;
-
- j = nlimbs - 1;
- a = 0;
- z = BYTES_PER_MPI_LIMB - nbytes % BYTES_PER_MPI_LIMB;
- z %= BYTES_PER_MPI_LIMB;
-
- while (sg_miter_next(&miter)) {
- buff = miter.addr;
- len = min_t(unsigned, miter.length, nbytes);
- nbytes -= len;
-
- for (x = 0; x < len; x++) {
- a <<= 8;
- a |= *buff++;
- if (((z + x + 1) % BYTES_PER_MPI_LIMB) == 0) {
- val->d[j--] = a;
- a = 0;
- }
- }
- z += x;
- }
-
- return val;
-}
-EXPORT_SYMBOL_GPL(mpi_read_raw_from_sgl);
-
-/* Perform a two's complement operation on buffer P of size N bytes. */
-static void twocompl(unsigned char *p, unsigned int n)
-{
- int i;
-
- for (i = n-1; i >= 0 && !p[i]; i--)
- ;
- if (i >= 0) {
- if ((p[i] & 0x01))
- p[i] = (((p[i] ^ 0xfe) | 0x01) & 0xff);
- else if ((p[i] & 0x02))
- p[i] = (((p[i] ^ 0xfc) | 0x02) & 0xfe);
- else if ((p[i] & 0x04))
- p[i] = (((p[i] ^ 0xf8) | 0x04) & 0xfc);
- else if ((p[i] & 0x08))
- p[i] = (((p[i] ^ 0xf0) | 0x08) & 0xf8);
- else if ((p[i] & 0x10))
- p[i] = (((p[i] ^ 0xe0) | 0x10) & 0xf0);
- else if ((p[i] & 0x20))
- p[i] = (((p[i] ^ 0xc0) | 0x20) & 0xe0);
- else if ((p[i] & 0x40))
- p[i] = (((p[i] ^ 0x80) | 0x40) & 0xc0);
- else
- p[i] = 0x80;
-
- for (i--; i >= 0; i--)
- p[i] ^= 0xff;
- }
-}
-
-int mpi_print(enum gcry_mpi_format format, unsigned char *buffer,
- size_t buflen, size_t *nwritten, MPI a)
-{
- unsigned int nbits = mpi_get_nbits(a);
- size_t len;
- size_t dummy_nwritten;
- int negative;
-
- if (!nwritten)
- nwritten = &dummy_nwritten;
-
- /* Libgcrypt does no always care to set clear the sign if the value
- * is 0. For printing this is a bit of a surprise, in particular
- * because if some of the formats don't support negative numbers but
- * should be able to print a zero. Thus we need this extra test
- * for a negative number.
- */
- if (a->sign && mpi_cmp_ui(a, 0))
- negative = 1;
- else
- negative = 0;
-
- len = buflen;
- *nwritten = 0;
- if (format == GCRYMPI_FMT_STD) {
- unsigned char *tmp;
- int extra = 0;
- unsigned int n;
-
- tmp = mpi_get_buffer(a, &n, NULL);
- if (!tmp)
- return -EINVAL;
-
- if (negative) {
- twocompl(tmp, n);
- if (!(*tmp & 0x80)) {
- /* Need to extend the sign. */
- n++;
- extra = 2;
- }
- } else if (n && (*tmp & 0x80)) {
- /* Positive but the high bit of the returned buffer is set.
- * Thus we need to print an extra leading 0x00 so that the
- * output is interpreted as a positive number.
- */
- n++;
- extra = 1;
- }
-
- if (buffer && n > len) {
- /* The provided buffer is too short. */
- kfree(tmp);
- return -E2BIG;
- }
- if (buffer) {
- unsigned char *s = buffer;
-
- if (extra == 1)
- *s++ = 0;
- else if (extra)
- *s++ = 0xff;
- memcpy(s, tmp, n-!!extra);
- }
- kfree(tmp);
- *nwritten = n;
- return 0;
- } else if (format == GCRYMPI_FMT_USG) {
- unsigned int n = (nbits + 7)/8;
-
- /* Note: We ignore the sign for this format. */
- /* FIXME: for performance reasons we should put this into
- * mpi_aprint because we can then use the buffer directly.
- */
-
- if (buffer && n > len)
- return -E2BIG;
- if (buffer) {
- unsigned char *tmp;
-
- tmp = mpi_get_buffer(a, &n, NULL);
- if (!tmp)
- return -EINVAL;
- memcpy(buffer, tmp, n);
- kfree(tmp);
- }
- *nwritten = n;
- return 0;
- } else if (format == GCRYMPI_FMT_PGP) {
- unsigned int n = (nbits + 7)/8;
-
- /* The PGP format can only handle unsigned integers. */
- if (negative)
- return -EINVAL;
-
- if (buffer && n+2 > len)
- return -E2BIG;
-
- if (buffer) {
- unsigned char *tmp;
- unsigned char *s = buffer;
-
- s[0] = nbits >> 8;
- s[1] = nbits;
-
- tmp = mpi_get_buffer(a, &n, NULL);
- if (!tmp)
- return -EINVAL;
- memcpy(s+2, tmp, n);
- kfree(tmp);
- }
- *nwritten = n+2;
- return 0;
- } else if (format == GCRYMPI_FMT_SSH) {
- unsigned char *tmp;
- int extra = 0;
- unsigned int n;
-
- tmp = mpi_get_buffer(a, &n, NULL);
- if (!tmp)
- return -EINVAL;
-
- if (negative) {
- twocompl(tmp, n);
- if (!(*tmp & 0x80)) {
- /* Need to extend the sign. */
- n++;
- extra = 2;
- }
- } else if (n && (*tmp & 0x80)) {
- n++;
- extra = 1;
- }
-
- if (buffer && n+4 > len) {
- kfree(tmp);
- return -E2BIG;
- }
-
- if (buffer) {
- unsigned char *s = buffer;
-
- *s++ = n >> 24;
- *s++ = n >> 16;
- *s++ = n >> 8;
- *s++ = n;
- if (extra == 1)
- *s++ = 0;
- else if (extra)
- *s++ = 0xff;
- memcpy(s, tmp, n-!!extra);
- }
- kfree(tmp);
- *nwritten = 4+n;
- return 0;
- } else if (format == GCRYMPI_FMT_HEX) {
- unsigned char *tmp;
- int i;
- int extra = 0;
- unsigned int n = 0;
-
- tmp = mpi_get_buffer(a, &n, NULL);
- if (!tmp)
- return -EINVAL;
- if (!n || (*tmp & 0x80))
- extra = 2;
-
- if (buffer && 2*n + extra + negative + 1 > len) {
- kfree(tmp);
- return -E2BIG;
- }
- if (buffer) {
- unsigned char *s = buffer;
-
- if (negative)
- *s++ = '-';
- if (extra) {
- *s++ = '0';
- *s++ = '0';
- }
-
- for (i = 0; i < n; i++) {
- unsigned int c = tmp[i];
-
- *s++ = (c >> 4) < 10 ? '0'+(c>>4) : 'A'+(c>>4)-10;
- c &= 15;
- *s++ = c < 10 ? '0'+c : 'A'+c-10;
- }
- *s++ = 0;
- *nwritten = s - buffer;
- } else {
- *nwritten = 2*n + extra + negative + 1;
- }
- kfree(tmp);
- return 0;
- } else
- return -EINVAL;
-}
-EXPORT_SYMBOL_GPL(mpi_print);
projects / linux-2.6-block.git / blobdiff