[linux-2.6-block.git] / kernel / module_signing.c

/* 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 <linux/errno.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);
}
Commit	Line	Data
106a4ee2 RR	1	/* Module signature checker
	2	*
	3	* Copyright (C) 2012 Red Hat, Inc. All Rights Reserved.
	4	* Written by David Howells (dhowells@redhat.com)
	5	*
	6	* This program is free software; you can redistribute it and/or
	7	* modify it under the terms of the GNU General Public Licence
	8	* as published by the Free Software Foundation; either version
	9	* 2 of the Licence, or (at your option) any later version.
	10	*/
	11
	12	#include <linux/kernel.h>
146aa8b1	13	#include <linux/errno.h>
b56e5a17	14	#include <keys/system_keyring.h>
3f1e1bea	15	#include <crypto/public_key.h>
106a4ee2 RR	16	#include "module-internal.h"
106a4ee2 RR	17
48ba2462 DH	18	/*
	19	* Module signature information block.
	20	*
	21	* The constituents of the signature section are, in order:
	22	*
	23	* - Signer's name
	24	* - Key identifier
	25	* - Signature data
	26	* - Information block
	27	*/
	28	struct module_signature {
3f1e1bea DH	29	u8 algo; /* Public-key crypto algorithm [0] */
	30	u8 hash; /* Digest algorithm [0] */
	31	u8 id_type; /* Key identifier type [PKEY_ID_PKCS7] */
	32	u8 signer_len; /* Length of signer's name [0] */
	33	u8 key_id_len; /* Length of key identifier [0] */
12e130b0 DH	34	u8 __pad[3];
12e130b0 DH	35	__be32 sig_len; /* Length of signature data */
48ba2462 DH	36	};
48ba2462 DH	37
106a4ee2 RR	38	/*
	39	* Verify the signature on a module.
	40	*/
caabe240	41	int mod_verify_sig(const void mod, unsigned long _modlen)
106a4ee2	42	{
48ba2462	43	struct module_signature ms;
caabe240	44	size_t modlen = *_modlen, sig_len;
48ba2462	45
0390c883	46	pr_devel("==>%s(,%zu)\n", __func__, modlen);
48ba2462	47
caabe240	48	if (modlen <= sizeof(ms))
48ba2462 DH	49	return -EBADMSG;
48ba2462 DH	50
caabe240 DH	51	memcpy(&ms, mod + (modlen - sizeof(ms)), sizeof(ms));
caabe240 DH	52	modlen -= sizeof(ms);
48ba2462 DH	53
48ba2462 DH	54	sig_len = be32_to_cpu(ms.sig_len);
caabe240	55	if (sig_len >= modlen)
48ba2462	56	return -EBADMSG;
caabe240	57	modlen -= sig_len;
caabe240	58	*_modlen = modlen;
48ba2462	59
3f1e1bea DH	60	if (ms.id_type != PKEY_ID_PKCS7) {
3f1e1bea DH	61	pr_err("Module is not signed with expected PKCS#7 message\n");
48ba2462	62	return -ENOPKG;
48ba2462 DH	63	}
48ba2462 DH	64
3f1e1bea DH	65	if (ms.algo != 0 \|\|
	66	ms.hash != 0 \|\|
	67	ms.signer_len != 0 \|\|
	68	ms.key_id_len != 0 \|\|
	69	ms.__pad[0] != 0 \|\|
	70	ms.__pad[1] != 0 \|\|
	71	ms.__pad[2] != 0) {
	72	pr_err("PKCS#7 signature info has unexpected non-zero params\n");
	73	return -EBADMSG;
	74	}
48ba2462	75
99db4435 DH	76	return system_verify_data(mod, modlen, mod + modlen, sig_len,
99db4435 DH	77	VERIFYING_MODULE_SIGNATURE);
106a4ee2	78	}