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-rw-r--r--lib/mpi/mpicoder.c752
1 files changed, 752 insertions, 0 deletions
diff --git a/lib/mpi/mpicoder.c b/lib/mpi/mpicoder.c
new file mode 100644
index 000000000..3cb6bd148
--- /dev/null
+++ b/lib/mpi/mpicoder.c
@@ -0,0 +1,752 @@
+/* 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);
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