kern: Add safe copyin() and copyout()

Introduce new routines that make it safer to transfer data between
userland and the kernel.

Signed-off-by: Ian Moffett <ian@osmora.org>

1 files changed, 59 insertions, 0 deletions

diff --git a/src/sys/include/os/systm.h b/src/sys/include/os/systm.h
new file mode 100644
index 0000000..33de08a
--- /dev/null
+++ b/src/sys/include/os/systm.h
@@ -0,0 +1,59 @@
+/*
+ * Copyright (c) 2025 Ian Marco Moffett and L5 engineers
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice,
+ *    this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. Neither the name of the project nor the names of its
+ *    contributors may be used to endorse or promote products derived from
+ *    this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#ifndef _OS_SYSTM_H_
+#define _OS_SYSTM_H_
+
+#include <sys/types.h>
+
+/*
+ * Copy userland data to kernel space safely
+ *
+ * @uaddr: Userspace source address to copy from
+ * @kaddr: Kernel address dest address to copy to
+ * @len: Length of buffer
+ *
+ * Returns 0 on success, otherwise a less than zero value
+ * on failure.
+ */
+int copyin(const void *uaddr, void *kaddr, size_t len);
+
+/*
+ * Copy kernel data to userland safely
+ *
+ * @kaddr: Kernel space address to copy from
+ * @uaddr: User space address to copy to
+ * @len: Length of bytes to copy
+ *
+ * Returns zero on success, otherwise a less than
+ * zero value.
+ */
+int copyout(const void *kaddr, void *uaddr, size_t len);
+
+#endif  /* !_OS_SYSTM_H_ */