Add mpi_read_raw_from_sgl and mpi_write_to_sgl helpers.
Signed-off-by: Tadeusz Struk <tadeusz.struk@xxxxxxxxx>
---
include/linux/mpi.h | 4 +
lib/mpi/mpicoder.c | 191 +++++++++++++++++++++++++++++++++++++++++++++++++++
2 files changed, 195 insertions(+)
diff --git a/include/linux/mpi.h b/include/linux/mpi.h
index 641b7d6..8b8269f 100644
--- a/include/linux/mpi.h
+++ b/include/linux/mpi.h
@@ -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
diff --git a/lib/mpi/mpicoder.c b/lib/mpi/mpicoder.c
index 95c52a9..ae1efa8 100644
--- a/lib/mpi/mpicoder.c
+++ b/lib/mpi/mpicoder.c
@@ -319,3 +319,194 @@ 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: 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)
+ 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);
+ 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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