Implement boot-time encryption key passing (keybuf)

This patch adds a general mechanism for providing encryption keys to the
kernel from the boot loader. This is intended to enable GELI support at
boot time, providing a better mechanism for passing keys to the kernel
than environment variables. It is designed to be extensible to other
applications, and can easily handle multiple encrypted volumes with
different keys.

This mechanism is currently used by the pending GELI EFI work.
Additionally, this mechanism can potentially be used to interface with
GRUB, opening up options for coreboot+GRUB configurations with completely
encrypted disks.

Another benefit over the existing system is that it does not require
re-deriving the user key from the password at each boot stage.

Most of this patch was written by Eric McCorkle. It was extended by
Allan Jude with a number of minor enhancements and extending the keybuf
feature into boot2.

GELI user keys are now derived once, in boot2, then passed to the loader,
which reuses the key, then passes it to the kernel, where the GELI module
destroys the keybuf after decrypting the volumes.

Submitted by:	Eric McCorkle <eric@metricspace.net> (Original Version)
Reviewed by:	oshogbo (earlier version), cem (earlier version)
MFC after:	3 weeks
Relnotes:	yes
Sponsored by:	ScaleEngine Inc.
Differential Revision:	https://reviews.freebsd.org/D9575

1 files changed, 64 insertions, 0 deletions

diff --git a/sys/crypto/intake.h b/sys/crypto/intake.h
new file mode 100644
index 000000000000..bdded3a767f2
--- /dev/null
+++ b/sys/crypto/intake.h
@@ -0,0 +1,64 @@
+/*-
+ * Copyright (c) 2016 Eric McCorkle
+ * 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.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR 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 AUTHOR 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.
+ *
+ * $FreeBSD$
+ */
+
+#ifndef _INTAKE_H_
+#define _INTAKE_H_
+
+#include  <sys/param.h>
+
+/*
+ * This file provides an interface for providing keys to the kernel
+ * during boot time.
+ */
+
+#define MAX_KEY_BITS	4096
+#define	MAX_KEY_BYTES	(MAX_KEY_BITS / NBBY)
+
+#define KEYBUF_SENTINEL	0xcee54b5d	/* KEYS4BSD */
+
+enum {
+        KEYBUF_TYPE_NONE,
+        KEYBUF_TYPE_GELI
+};
+
+struct keybuf_ent {
+        unsigned int ke_type;
+        char ke_data[MAX_KEY_BYTES];
+};
+
+struct keybuf {
+        unsigned int kb_nents;
+        struct keybuf_ent kb_ents[];
+};
+
+#ifdef _KERNEL
+/* Get the key intake buffer */
+extern struct keybuf* get_keybuf(void);
+#endif
+
+#endif