linux/crypto/asymmetric_keys/verify_pefile.c

// SPDX-License-Identifier: GPL-2.0-or-later
/* Parse a signed PE binary
 *
 * Copyright (C) 2014 Red Hat, Inc. All Rights Reserved.
 * Written by David Howells ([email protected])
 */

#define pr_fmt(fmt) …
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/err.h>
#include <linux/pe.h>
#include <linux/asn1.h>
#include <linux/verification.h>
#include <crypto/hash.h>
#include "verify_pefile.h"

/*
 * Parse a PE binary.
 */
static int pefile_parse_binary(const void *pebuf, unsigned int pelen,
			       struct pefile_context *ctx)
{ … }

/*
 * Check and strip the PE wrapper from around the signature and check that the
 * remnant looks something like PKCS#7.
 */
static int pefile_strip_sig_wrapper(const void *pebuf,
				    struct pefile_context *ctx)
{ … }

/*
 * Compare two sections for canonicalisation.
 */
static int pefile_compare_shdrs(const void *a, const void *b)
{ … }

/*
 * Load the contents of the PE binary into the digest, leaving out the image
 * checksum and the certificate data block.
 */
static int pefile_digest_pe_contents(const void *pebuf, unsigned int pelen,
				     struct pefile_context *ctx,
				     struct shash_desc *desc)
{ … }

/*
 * Digest the contents of the PE binary, leaving out the image checksum and the
 * certificate data block.
 */
static int pefile_digest_pe(const void *pebuf, unsigned int pelen,
			    struct pefile_context *ctx)
{ … }

/**
 * verify_pefile_signature - Verify the signature on a PE binary image
 * @pebuf: Buffer containing the PE binary image
 * @pelen: Length of the binary image
 * @trusted_keys: Signing certificate(s) to use as starting points
 * @usage: The use to which the key is being put.
 *
 * Validate that the certificate chain inside the PKCS#7 message inside the PE
 * binary image intersects keys we already know and trust.
 *
 * Returns, in order of descending priority:
 *
 *  (*) -ELIBBAD if the image cannot be parsed, or:
 *
 *  (*) -EKEYREJECTED if a signature failed to match for which we have a valid
 *	key, or:
 *
 *  (*) 0 if at least one signature chain intersects with the keys in the trust
 *	keyring, or:
 *
 *  (*) -ENODATA if there is no signature present.
 *
 *  (*) -ENOPKG if a suitable crypto module couldn't be found for a check on a
 *	chain.
 *
 *  (*) -ENOKEY if we couldn't find a match for any of the signature chains in
 *	the message.
 *
 * May also return -ENOMEM.
 */
int verify_pefile_signature(const void *pebuf, unsigned pelen,
			    struct key *trusted_keys,
			    enum key_being_used_for usage)
{ … }