/* Module signature checker * * Copyright (C) 2012 Red Hat, Inc. All Rights Reserved. * Written by David Howells (dhowells@redhat.com) * * This program is free software; you can redistribute it and/or * modify it under the terms of the GNU General Public Licence * as published by the Free Software Foundation; either version * 2 of the Licence, or (at your option) any later version. */ #include <linux/kernel.h>#include <keys/system_keyring.h>#include <crypto/public_key.h>#include "module-internal.h" /* * Module signature information block. * * The constituents of the signature section are, in order: * *	- Signer's name *	- Key identifier *	- Signature data *	- Information block */struct module_signature {	u8	algo;		/* Public-key crypto algorithm [0] */	u8	hash;		/* Digest algorithm [0] */	u8	id_type;	/* Key identifier type [PKEY_ID_PKCS7] */	u8	signer_len;	/* Length of signer's name [0] */	u8	key_id_len;	/* Length of key identifier [0] */	u8	__pad[3];	__be32	sig_len;	/* Length of signature data */}; /* * Verify the signature on a module. */int mod_verify_sig(const void *mod, unsigned long *_modlen){	struct module_signature ms;	size_t modlen = *_modlen, sig_len; 	pr_devel("==>%s(,%zu)\n", __func__, modlen); 	if (modlen <= sizeof(ms))		return -EBADMSG; 	memcpy(&ms, mod + (modlen - sizeof(ms)), sizeof(ms));	modlen -= sizeof(ms); 	sig_len = be32_to_cpu(ms.sig_len);	if (sig_len >= modlen)		return -EBADMSG;	modlen -= sig_len;	*_modlen = modlen; 	if (ms.id_type != PKEY_ID_PKCS7) {		pr_err("Module is not signed with expected PKCS#7 message\n");		return -ENOPKG;	} 	if (ms.algo != 0 ||	    ms.hash != 0 ||	    ms.signer_len != 0 ||	    ms.key_id_len != 0 ||	    ms.__pad[0] != 0 ||	    ms.__pad[1] != 0 ||	    ms.__pad[2] != 0) {		pr_err("PKCS#7 signature info has unexpected non-zero params\n");		return -EBADMSG;	} 	return system_verify_data(mod, modlen, mod + modlen, sig_len,				  VERIFYING_MODULE_SIGNATURE);}