MPILIB: add mpi_read_buf() and mpi_get_size() helpers
Added a mpi_read_buf() helper function to export MPI to a buf provided by
the user, and a mpi_get_size() helper, that tells the user how big the buf is.
Changed mpi_free to use kzfree instead of kfree because it is used to free
crypto keys.
Signed-off-by: Tadeusz Struk <tadeusz.struk@intel.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
diff --git a/lib/mpi/mpicoder.c b/lib/mpi/mpicoder.c
index 4cc6442..bc0a1da 100644
--- a/lib/mpi/mpicoder.c
+++ b/lib/mpi/mpicoder.c
@@ -128,28 +128,36 @@
}
EXPORT_SYMBOL_GPL(mpi_read_from_buffer);
-/****************
- * Return an allocated buffer with the MPI (msb first).
- * NBYTES receives the length of this buffer. 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. If sign is not NULL, it will
- * be set to the sign of the A.
+/**
+ * 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
*/
-void *mpi_get_buffer(MPI a, unsigned *nbytes, int *sign)
+int mpi_read_buffer(MPI a, uint8_t *buf, unsigned buf_len, unsigned *nbytes,
+ int *sign)
{
- uint8_t *p, *buffer;
+ uint8_t *p;
mpi_limb_t alimb;
+ unsigned int n = mpi_get_size(a);
int i;
- unsigned int n;
+
+ if (buf_len < n || !buf)
+ return -EINVAL;
if (sign)
*sign = a->sign;
- *nbytes = n = a->nlimbs * BYTES_PER_MPI_LIMB;
- if (!n)
- n++; /* avoid zero length allocation */
- p = buffer = kmalloc(n, GFP_KERNEL);
- if (!p)
- return NULL;
+
+ if (nbytes)
+ *nbytes = n;
+
+ p = buf;
for (i = a->nlimbs - 1; i >= 0; i--) {
alimb = a->d[i];
@@ -171,15 +179,56 @@
#error please implement for this limb size.
#endif
}
+ 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, *p;
+ 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;
+ }
/* this is sub-optimal but we need to do the shift operation
* because the caller has to free the returned buffer */
- for (p = buffer; !*p && *nbytes; p++, --*nbytes)
+ for (p = buf; !*p && *nbytes; p++, --*nbytes)
;
- if (p != buffer)
- memmove(buffer, p, *nbytes);
+ if (p != buf)
+ memmove(buf, p, *nbytes);
- return buffer;
+ return buf;
}
EXPORT_SYMBOL_GPL(mpi_get_buffer);