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@xxxxxxxxx>
---
include/linux/mpi.h | 15 +++++++++
lib/mpi/mpicoder.c | 87 ++++++++++++++++++++++++++++++++++++++++-----------
lib/mpi/mpiutil.c | 6 ++--
3 files changed, 86 insertions(+), 22 deletions(-)
diff --git a/include/linux/mpi.h b/include/linux/mpi.h
index 5af1b81..641b7d6 100644
--- a/include/linux/mpi.h
+++ b/include/linux/mpi.h
@@ -81,6 +81,8 @@ MPI mpi_read_from_buffer(const void *buffer, unsigned *ret_nread);
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);
+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);
@@ -142,4 +144,17 @@ int mpi_rshift(MPI x, MPI a, unsigned n);
/*-- mpi-inv.c --*/
int mpi_invm(MPI x, MPI u, MPI v);
+/* inline functions */
+
+/**
+ * mpi_get_size() - returns max size required to store the number
+ *
+ * @a: A multi precision integer for which we want to allocate a bufer
+ *
+ * Return: size required to store the number
+ */
+static inline unsigned int mpi_get_size(MPI a)
+{
+ return a->nlimbs * BYTES_PER_MPI_LIMB;
+}
#endif /*G10_MPI_H */
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 @@ leave:
}
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 @@ void *mpi_get_buffer(MPI a, unsigned *nbytes, int *sign)
#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);
diff --git a/lib/mpi/mpiutil.c b/lib/mpi/mpiutil.c
index bf076d2..314f4df 100644
--- a/lib/mpi/mpiutil.c
+++ b/lib/mpi/mpiutil.c
@@ -69,7 +69,7 @@ void mpi_free_limb_space(mpi_ptr_t a)
if (!a)
return;
- kfree(a);
+ kzfree(a);
}
void mpi_assign_limb_space(MPI a, mpi_ptr_t ap, unsigned nlimbs)
@@ -95,7 +95,7 @@ int mpi_resize(MPI a, unsigned nlimbs)
if (!p)
return -ENOMEM;
memcpy(p, a->d, a->alloced * sizeof(mpi_limb_t));
- kfree(a->d);
+ kzfree(a->d);
a->d = p;
} else {
a->d = kzalloc(nlimbs * sizeof(mpi_limb_t), GFP_KERNEL);
@@ -112,7 +112,7 @@ void mpi_free(MPI a)
return;
if (a->flags & 4)
- kfree(a->d);
+ kzfree(a->d);
else
mpi_free_limb_space(a->d);
--
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