diff options
Diffstat (limited to 'kernel/lib/mpi/mpicoder.c')
| -rw-r--r-- | kernel/lib/mpi/mpicoder.c | 260 |
1 files changed, 260 insertions, 0 deletions
diff --git a/kernel/lib/mpi/mpicoder.c b/kernel/lib/mpi/mpicoder.c new file mode 100644 index 000000000..4cc644273 --- /dev/null +++ b/kernel/lib/mpi/mpicoder.c @@ -0,0 +1,260 @@ +/* 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 <asm-generic/bitops/count_zeros.h> +#include "mpi-internal.h" + +#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]); + else + nbits = 0; + + 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; + int i, j; + unsigned nbits, nbytes, nlimbs, nread = 0; + mpi_limb_t a; + MPI val = NULL; + + if (*ret_nread < 2) + goto leave; + nbits = buffer[0] << 8 | buffer[1]; + + if (nbits > MAX_EXTERN_MPI_BITS) { + pr_info("MPI: mpi too large (%u bits)\n", nbits); + goto leave; + } + buffer += 2; + nread = 2; + + nbytes = DIV_ROUND_UP(nbits, 8); + nlimbs = DIV_ROUND_UP(nbytes, BYTES_PER_MPI_LIMB); + val = mpi_alloc(nlimbs); + if (!val) + return NULL; + i = BYTES_PER_MPI_LIMB - nbytes % BYTES_PER_MPI_LIMB; + i %= BYTES_PER_MPI_LIMB; + val->nbits = nbits; + j = val->nlimbs = nlimbs; + val->sign = 0; + for (; j > 0; j--) { + a = 0; + for (; i < BYTES_PER_MPI_LIMB; i++) { + if (++nread > *ret_nread) { + printk + ("MPI: mpi larger than buffer nread=%d ret_nread=%d\n", + nread, *ret_nread); + goto leave; + } + a <<= 8; + a |= *buffer++; + } + i = 0; + val->d[j - 1] = a; + } + +leave: + *ret_nread = nread; + return val; +} +EXPORT_SYMBOL_GPL(mpi_read_from_buffer); + +/**************** + * Return an allocated buffer with the MPI (msb first). + * NBYTES receives the length of this buffer. 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. If sign is not NULL, it will + * be set to the sign of the A. + */ +void *mpi_get_buffer(MPI a, unsigned *nbytes, int *sign) +{ + uint8_t *p, *buffer; + mpi_limb_t alimb; + int i; + unsigned int n; + + if (sign) + *sign = a->sign; + *nbytes = n = a->nlimbs * BYTES_PER_MPI_LIMB; + if (!n) + n++; /* avoid zero length allocation */ + p = buffer = kmalloc(n, GFP_KERNEL); + if (!p) + return NULL; + + for (i = a->nlimbs - 1; i >= 0; i--) { + alimb = a->d[i]; +#if BYTES_PER_MPI_LIMB == 4 + *p++ = alimb >> 24; + *p++ = alimb >> 16; + *p++ = alimb >> 8; + *p++ = alimb; +#elif BYTES_PER_MPI_LIMB == 8 + *p++ = alimb >> 56; + *p++ = alimb >> 48; + *p++ = alimb >> 40; + *p++ = alimb >> 32; + *p++ = alimb >> 24; + *p++ = alimb >> 16; + *p++ = alimb >> 8; + *p++ = alimb; +#else +#error please implement for this limb size. +#endif + } + + /* this is sub-optimal but we need to do the shift operation + * because the caller has to free the returned buffer */ + for (p = buffer; !*p && *nbytes; p++, --*nbytes) + ; + if (p != buffer) + memmove(buffer, p, *nbytes); + + return buffer; +} +EXPORT_SYMBOL_GPL(mpi_get_buffer); + +/**************** + * Use BUFFER to update MPI. + */ +int mpi_set_buffer(MPI a, const void *xbuffer, unsigned nbytes, int sign) +{ + const uint8_t *buffer = xbuffer, *p; + mpi_limb_t alimb; + int nlimbs; + int i; + + nlimbs = DIV_ROUND_UP(nbytes, BYTES_PER_MPI_LIMB); + if (RESIZE_IF_NEEDED(a, nlimbs) < 0) + return -ENOMEM; + a->sign = sign; + + for (i = 0, p = buffer + nbytes - 1; p >= buffer + BYTES_PER_MPI_LIMB;) { +#if BYTES_PER_MPI_LIMB == 4 + alimb = (mpi_limb_t) *p--; + alimb |= (mpi_limb_t) *p-- << 8; + alimb |= (mpi_limb_t) *p-- << 16; + alimb |= (mpi_limb_t) *p-- << 24; +#elif BYTES_PER_MPI_LIMB == 8 + alimb = (mpi_limb_t) *p--; + alimb |= (mpi_limb_t) *p-- << 8; + alimb |= (mpi_limb_t) *p-- << 16; + alimb |= (mpi_limb_t) *p-- << 24; + alimb |= (mpi_limb_t) *p-- << 32; + alimb |= (mpi_limb_t) *p-- << 40; + alimb |= (mpi_limb_t) *p-- << 48; + alimb |= (mpi_limb_t) *p-- << 56; +#else +#error please implement for this limb size. +#endif + a->d[i++] = alimb; + } + if (p >= buffer) { +#if BYTES_PER_MPI_LIMB == 4 + alimb = *p--; + if (p >= buffer) + alimb |= (mpi_limb_t) *p-- << 8; + if (p >= buffer) + alimb |= (mpi_limb_t) *p-- << 16; + if (p >= buffer) + alimb |= (mpi_limb_t) *p-- << 24; +#elif BYTES_PER_MPI_LIMB == 8 + alimb = (mpi_limb_t) *p--; + if (p >= buffer) + alimb |= (mpi_limb_t) *p-- << 8; + if (p >= buffer) + alimb |= (mpi_limb_t) *p-- << 16; + if (p >= buffer) + alimb |= (mpi_limb_t) *p-- << 24; + if (p >= buffer) + alimb |= (mpi_limb_t) *p-- << 32; + if (p >= buffer) + alimb |= (mpi_limb_t) *p-- << 40; + if (p >= buffer) + alimb |= (mpi_limb_t) *p-- << 48; + if (p >= buffer) + alimb |= (mpi_limb_t) *p-- << 56; +#else +#error please implement for this limb size. +#endif + a->d[i++] = alimb; + } + a->nlimbs = i; + + if (i != nlimbs) { + pr_emerg("MPI: mpi_set_buffer: Assertion failed (%d != %d)", i, + nlimbs); + BUG(); + } + return 0; +} +EXPORT_SYMBOL_GPL(mpi_set_buffer); |