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-rw-r--r--lib/mpi/mpicoder.c520
1 files changed, 520 insertions, 0 deletions
diff --git a/lib/mpi/mpicoder.c b/lib/mpi/mpicoder.c
new file mode 100644
index 000000000000..e37dbf53e226
--- /dev/null
+++ b/lib/mpi/mpicoder.c
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+/* 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 "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);
+
+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 bufer provided by user (msb first)
+ *
+ * @a: a multi precision integer
+ * @buf: bufer to which the output will be written to. Needs to be at
+ * leaset mpi_get_size(a) long.
+ * @buf_len: size of the buf.
+ * @nbytes: receives the actual length of the data written.
+ * @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;
+ mpi_limb_t alimb;
+ unsigned int n = mpi_get_size(a);
+ int i, lzeros;
+
+ if (buf_len < n || !buf || !nbytes)
+ return -EINVAL;
+
+ if (sign)
+ *sign = a->sign;
+
+ lzeros = count_lzeros(a);
+
+ p = buf;
+ *nbytes = n - lzeros;
+
+ 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
+
+ if (lzeros > 0) {
+ if (lzeros >= sizeof(alimb)) {
+ p -= sizeof(alimb);
+ } else {
+ mpi_limb_t *limb1 = (void *)p - sizeof(alimb);
+ mpi_limb_t *limb2 = (void *)p - sizeof(alimb)
+ + lzeros;
+ *limb1 = *limb2;
+ p -= lzeros;
+ }
+ lzeros -= sizeof(alimb);
+ }
+ }
+ 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);
+
+/****************
+ * 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);
+
+/**
+ * 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: in/out param - it has the be set to the maximum number of
+ * bytes that can be written to sgl. This has to be at least
+ * the size of the integer a. On return it receives the actual
+ * length of the data written.
+ * @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;
+ mpi_limb_t alimb, alimb2;
+ unsigned int n = mpi_get_size(a);
+ int i, x, y = 0, lzeros, buf_len;
+
+ if (!nbytes || *nbytes < n)
+ return -EINVAL;
+
+ if (sign)
+ *sign = a->sign;
+
+ lzeros = count_lzeros(a);
+
+ *nbytes = n - lzeros;
+ buf_len = sgl->length;
+ p2 = sg_virt(sgl);
+
+ for (i = a->nlimbs - 1 - lzeros / BYTES_PER_MPI_LIMB,
+ lzeros %= BYTES_PER_MPI_LIMB;
+ i >= 0; i--) {
+ alimb = a->d[i];
+ p = (u8 *)&alimb2;
+#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
+ if (lzeros > 0) {
+ mpi_limb_t *limb1 = (void *)p - sizeof(alimb);
+ mpi_limb_t *limb2 = (void *)p - sizeof(alimb)
+ + lzeros;
+ *limb1 = *limb2;
+ p -= lzeros;
+ y = lzeros;
+ lzeros -= sizeof(alimb);
+ }
+
+ p = p - (sizeof(alimb) - y);
+
+ for (x = 0; x < sizeof(alimb) - y; x++) {
+ if (!buf_len) {
+ sgl = sg_next(sgl);
+ if (!sgl)
+ return -EINVAL;
+ buf_len = sgl->length;
+ p2 = sg_virt(sgl);
+ }
+ *p2++ = *p++;
+ buf_len--;
+ }
+ y = 0;
+ }
+ 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
+ * @len: 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 len)
+{
+ struct scatterlist *sg;
+ int x, i, j, z, lzeros, ents;
+ unsigned int nbits, nlimbs, nbytes;
+ mpi_limb_t a;
+ MPI val = NULL;
+
+ lzeros = 0;
+ ents = sg_nents(sgl);
+
+ for_each_sg(sgl, sg, ents, i) {
+ const u8 *buff = sg_virt(sg);
+ int len = sg->length;
+
+ while (len && !*buff) {
+ lzeros++;
+ len--;
+ buff++;
+ }
+
+ if (len && *buff)
+ break;
+
+ ents--;
+ lzeros = 0;
+ }
+
+ sgl = sg;
+
+ if (!ents)
+ nbytes = 0;
+ else
+ nbytes = len - lzeros;
+
+ 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(*(u8 *)(sg_virt(sgl) + lzeros));
+ 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)
+ return val;
+
+ j = nlimbs - 1;
+ a = 0;
+ z = 0;
+ x = BYTES_PER_MPI_LIMB - nbytes % BYTES_PER_MPI_LIMB;
+ x %= BYTES_PER_MPI_LIMB;
+
+ for_each_sg(sgl, sg, ents, i) {
+ const u8 *buffer = sg_virt(sg) + lzeros;
+ int len = sg->length - lzeros;
+ int buf_shift = x;
+
+ if (sg_is_last(sg) && (len % BYTES_PER_MPI_LIMB))
+ len += BYTES_PER_MPI_LIMB - (len % BYTES_PER_MPI_LIMB);
+
+ for (; x < len + buf_shift; x++) {
+ a <<= 8;
+ a |= *buffer++;
+ if (((z + x + 1) % BYTES_PER_MPI_LIMB) == 0) {
+ val->d[j--] = a;
+ a = 0;
+ }
+ }
+ z += x;
+ x = 0;
+ lzeros = 0;
+ }
+ return val;
+}
+EXPORT_SYMBOL_GPL(mpi_read_raw_from_sgl);
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