/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License (the "License").
 * You may not use this file except in compliance with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */

/*
 * Copyright 2008 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 *
 * Copyright 2021 OmniOS Community Edition (OmniOSce) Association.
 * Copyright 2025 Oxide Computer Company
 */

#include <sys/types.h>
#include <sys/ucode.h>
#include <sys/ucode_intel.h>
#ifdef	_KERNEL
#include <sys/systm.h>
#else
#include <strings.h>
#endif

/*
 * Refer to
 *	Intel 64 and IA-32 Architectures Software Developers's Manual
 *		Chapter 9.11 Microcode Update Facilities	[1]
 * for details.
 */

/*
 * Validates the microcode header.
 * Returns EM_OK on success, EM_HEADER on failure.
 */
ucode_errno_t
ucode_header_validate_intel(ucode_header_intel_t *uhp)
{
	uint32_t header_size, body_size, total_size;

	if (uhp == NULL)
		return (EM_HEADER);

	/*
	 * The only header version number supported is 1.
	 */
	if (uhp->uh_header_ver != 0x1)
		return (EM_HEADER);

	header_size = UCODE_HEADER_SIZE_INTEL;
	total_size = UCODE_TOTAL_SIZE_INTEL(uhp->uh_total_size);
	body_size = UCODE_BODY_SIZE_INTEL(uhp->uh_body_size);

	/*
	 * The body size field of the microcode code header specifies the size
	 * of the encrypted data section, its value must be a multiple of the
	 * size of DWORD.  The total size field must be in multiples of 1K
	 * bytes.
	 */
	if ((body_size % sizeof (int)) != 0 ||
	    (total_size < header_size + body_size) ||
	    (total_size % UCODE_KB(1)) != 0) {
		return (EM_HEADER);
	}

	/*
	 * Sanity check to avoid reading bogus files
	 */
	if (total_size < UCODE_MIN_SIZE || total_size > UCODE_MAX_SIZE)
		return (EM_HEADER);

	/*
	 * If there is extended signature table, total_size is the sum of
	 *	header_size
	 *	body_size
	 *	sizeof (struct ucode_ext_table)
	 *	n * sizeof (struct ucode_ext_sig)
	 * where n is indicated by uet_count in struct ucode_ext_table.
	 */
	if (total_size > (header_size + body_size)) {
		if ((total_size - body_size - header_size -
		    UCODE_EXT_TABLE_SIZE_INTEL) % UCODE_EXT_SIG_SIZE_INTEL) {
			return (EM_HEADER);
		}
	}

	return (EM_OK);
}

/*
 * Returns checksum.
 */
uint32_t
ucode_checksum_intel(uint32_t sum, uint32_t size, uint8_t *code)
{
	int i;
	uint32_t *lcode = (uint32_t *)(intptr_t)code;

	i = size >> 2;
	while (i--)
		sum += lcode[i];

	return (sum);
}

uint32_t
ucode_checksum_intel_extsig(ucode_header_intel_t *uhp,
    ucode_ext_sig_intel_t *uesp)
{
	/*
	 * From [1], table 9-7, the checksum field contained in the extended
	 * patch signature is the checksum across the entire update which would
	 * result if the primary processor signature and processor flags were
	 * replaced with the values from this entry.
	 *
	 * We can therefore just calculate the difference in the checksum
	 * between the old and new values and return that to the caller. If the
	 * difference is zero then the checksum for the patch is valid.
	 */
	uint32_t diff;

	diff = uesp->ues_signature + uesp->ues_proc_flags + uesp->ues_checksum;
	diff -= uhp->uh_signature + uhp->uh_proc_flags + uhp->uh_checksum;

	return (diff);
}

ucode_errno_t
ucode_validate_intel(uint8_t *ucodep, size_t size)
{
	uint32_t header_size = UCODE_HEADER_SIZE_INTEL;
	size_t remaining;

	if (ucodep == NULL || size <= 0)
		return (EM_INVALIDARG);

	for (remaining = size; remaining > 0; ) {
		uint32_t total_size, body_size, ext_size;
		uint8_t *curbuf = &ucodep[size - remaining];
		ucode_header_intel_t *uhp = (ucode_header_intel_t *)curbuf;
		ucode_errno_t rc;

		if ((rc = ucode_header_validate_intel(uhp)) != EM_OK)
			return (rc);

		total_size = UCODE_TOTAL_SIZE_INTEL(uhp->uh_total_size);

		if (ucode_checksum_intel(0, total_size, curbuf) != 0)
			return (EM_CHECKSUM);

		body_size = UCODE_BODY_SIZE_INTEL(uhp->uh_body_size);
		ext_size = total_size - (header_size + body_size);

		if (ext_size > 0) {
			ucode_ext_table_intel_t *ext;
			uint32_t i;

			ext = (ucode_ext_table_intel_t *)
			    &curbuf[header_size + body_size];

			if (ucode_checksum_intel(0, ext_size, (uint8_t *)ext))
				return (EM_EXTCHECKSUM);

			for (i = 0; i < ext->uet_count; i++) {
				ucode_ext_sig_intel_t *sig =
				    &ext->uet_ext_sig[i];

				if (ucode_checksum_intel_extsig(uhp, sig) != 0)
					return (EM_SIGCHECKSUM);
			}
		}

		remaining -= total_size;
	}
	return (EM_OK);
}