Commit 2d4d1eea authored by Tadeusz Struk's avatar Tadeusz Struk Committed by Herbert Xu

lib/mpi: Add mpi sgl helpers

Add mpi_read_raw_from_sgl and mpi_write_to_sgl helpers.
Signed-off-by: default avatarTadeusz Struk <tadeusz.struk@intel.com>
Signed-off-by: default avatarHerbert Xu <herbert@gondor.apana.org.au>
parent 9ad92bdf
......@@ -31,6 +31,7 @@
#define G10_MPI_H
#include <linux/types.h>
#include <linux/scatterlist.h>
/* DSI defines */
......@@ -78,6 +79,7 @@ void mpi_swap(MPI a, MPI b);
MPI do_encode_md(const void *sha_buffer, unsigned nbits);
MPI mpi_read_raw_data(const void *xbuffer, size_t nbytes);
MPI mpi_read_from_buffer(const void *buffer, unsigned *ret_nread);
MPI mpi_read_raw_from_sgl(struct scatterlist *sgl, unsigned int len);
int mpi_fromstr(MPI val, const char *str);
u32 mpi_get_keyid(MPI a, u32 *keyid);
void *mpi_get_buffer(MPI a, unsigned *nbytes, int *sign);
......@@ -85,6 +87,8 @@ int mpi_read_buffer(MPI a, uint8_t *buf, unsigned buf_len, unsigned *nbytes,
int *sign);
void *mpi_get_secure_buffer(MPI a, unsigned *nbytes, int *sign);
int mpi_set_buffer(MPI a, const void *buffer, unsigned nbytes, int sign);
int mpi_write_to_sgl(MPI a, struct scatterlist *sg, unsigned *nbytes,
int *sign);
#define log_mpidump g10_log_mpidump
......
......@@ -319,3 +319,199 @@ int mpi_set_buffer(MPI a, const void *xbuffer, unsigned nbytes, int sign)
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 = 0, buf_len;
if (!nbytes || *nbytes < n)
return -EINVAL;
if (sign)
*sign = a->sign;
p = (void *)&a->d[a->nlimbs] - 1;
for (i = a->nlimbs * sizeof(alimb) - 1; i >= 0; i--, p--) {
if (!*p)
lzeros++;
else
break;
}
*nbytes = n - lzeros;
buf_len = sgl->length;
p2 = sg_virt(sgl);
for (i = a->nlimbs - 1; 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) {
if (lzeros >= sizeof(alimb)) {
p -= sizeof(alimb);
continue;
} else {
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++;
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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