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Linux kernel mirror (for testing) git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
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#include <linux/bitops.h>#include <linux/byteorder/generic.h>#include <linux/count_zeros.h>#include <linux/export.h>#include <linux/scatterlist.h>#include <linux/string.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]) - (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);
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 < nbytes) { 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(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);