[deliverable/linux.git] / crypto / asymmetric_keys / pkcs7_verify.c

/* Verify the signature on a PKCS#7 message.
 *
 * 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.
 */

#define pr_fmt(fmt) "PKCS7: "fmt
#include <linux/kernel.h>
#include <linux/export.h>
#include <linux/slab.h>
#include <linux/err.h>
#include <linux/asn1.h>
#include <crypto/hash.h>
#include <crypto/public_key.h>
#include "pkcs7_parser.h"

/*
 * Digest the relevant parts of the PKCS#7 data
 */
static int pkcs7_digest(struct pkcs7_message *pkcs7,
			struct pkcs7_signed_info *sinfo)
{
	struct crypto_shash *tfm;
	struct shash_desc *desc;
	size_t digest_size, desc_size;
	void *digest;
	int ret;

	kenter(",%u,%s", sinfo->index, sinfo->sig.hash_algo);

	if (!sinfo->sig.hash_algo)
		return -ENOPKG;

	/* Allocate the hashing algorithm we're going to need and find out how
	 * big the hash operational data will be.
	 */
	tfm = crypto_alloc_shash(sinfo->sig.hash_algo, 0, 0);
	if (IS_ERR(tfm))
		return (PTR_ERR(tfm) == -ENOENT) ? -ENOPKG : PTR_ERR(tfm);

	desc_size = crypto_shash_descsize(tfm) + sizeof(*desc);
	sinfo->sig.digest_size = digest_size = crypto_shash_digestsize(tfm);

	ret = -ENOMEM;
	digest = kzalloc(ALIGN(digest_size, __alignof__(*desc)) + desc_size,
			 GFP_KERNEL);
	if (!digest)
		goto error_no_desc;

	desc = PTR_ALIGN(digest + digest_size, __alignof__(*desc));
	desc->tfm   = tfm;
	desc->flags = CRYPTO_TFM_REQ_MAY_SLEEP;

	/* Digest the message [RFC2315 9.3] */
	ret = crypto_shash_init(desc);
	if (ret < 0)
		goto error;
	ret = crypto_shash_finup(desc, pkcs7->data, pkcs7->data_len, digest);
	if (ret < 0)
		goto error;
	pr_devel("MsgDigest = [%*ph]\n", 8, digest);

	/* However, if there are authenticated attributes, there must be a
	 * message digest attribute amongst them which corresponds to the
	 * digest we just calculated.
	 */
	if (sinfo->authattrs) {
		u8 tag;

		if (!sinfo->msgdigest) {
			pr_warn("Sig %u: No messageDigest\n", sinfo->index);
			ret = -EKEYREJECTED;
			goto error;
		}

		if (sinfo->msgdigest_len != sinfo->sig.digest_size) {
			pr_debug("Sig %u: Invalid digest size (%u)\n",
				 sinfo->index, sinfo->msgdigest_len);
			ret = -EBADMSG;
			goto error;
		}

		if (memcmp(digest, sinfo->msgdigest, sinfo->msgdigest_len) != 0) {
			pr_debug("Sig %u: Message digest doesn't match\n",
				 sinfo->index);
			ret = -EKEYREJECTED;
			goto error;
		}

		/* We then calculate anew, using the authenticated attributes
		 * as the contents of the digest instead.  Note that we need to
		 * convert the attributes from a CONT.0 into a SET before we
		 * hash it.
		 */
		memset(digest, 0, sinfo->sig.digest_size);

		ret = crypto_shash_init(desc);
		if (ret < 0)
			goto error;
		tag = ASN1_CONS_BIT | ASN1_SET;
		ret = crypto_shash_update(desc, &tag, 1);
		if (ret < 0)
			goto error;
		ret = crypto_shash_finup(desc, sinfo->authattrs,
					 sinfo->authattrs_len, digest);
		if (ret < 0)
			goto error;
		pr_devel("AADigest = [%*ph]\n", 8, digest);
	}

	sinfo->sig.digest = digest;
	digest = NULL;

error:
	kfree(digest);
error_no_desc:
	crypto_free_shash(tfm);
	kleave(" = %d", ret);
	return ret;
}

/*
 * Find the key (X.509 certificate) to use to verify a PKCS#7 message.  PKCS#7
 * uses the issuer's name and the issuing certificate serial number for
 * matching purposes.  These must match the certificate issuer's name (not
 * subject's name) and the certificate serial number [RFC 2315 6.7].
 */
static int pkcs7_find_key(struct pkcs7_message *pkcs7,
			  struct pkcs7_signed_info *sinfo)
{
	struct x509_certificate *x509;
	unsigned certix = 1;

	kenter("%u", sinfo->index);

	for (x509 = pkcs7->certs; x509; x509 = x509->next, certix++) {
		/* I'm _assuming_ that the generator of the PKCS#7 message will
		 * encode the fields from the X.509 cert in the same way in the
		 * PKCS#7 message - but I can't be 100% sure of that.  It's
		 * possible this will need element-by-element comparison.
		 */
		if (!asymmetric_key_id_same(x509->id, sinfo->signing_cert_id))
			continue;
		pr_devel("Sig %u: Found cert serial match X.509[%u]\n",
			 sinfo->index, certix);

		if (x509->pub->pkey_algo != sinfo->sig.pkey_algo) {
			pr_warn("Sig %u: X.509 algo and PKCS#7 sig algo don't match\n",
				sinfo->index);
			continue;
		}

		sinfo->signer = x509;
		return 0;
	}

	/* The relevant X.509 cert isn't found here, but it might be found in
	 * the trust keyring.
	 */
	pr_debug("Sig %u: Issuing X.509 cert not found (#%*phN)\n",
		 sinfo->index,
		 sinfo->signing_cert_id->len, sinfo->signing_cert_id->data);
	return 0;
}

/*
 * Verify the internal certificate chain as best we can.
 */
static int pkcs7_verify_sig_chain(struct pkcs7_message *pkcs7,
				  struct pkcs7_signed_info *sinfo)
{
	struct x509_certificate *x509 = sinfo->signer, *p;
	struct asymmetric_key_id *auth;
	int ret;

	kenter("");

	for (p = pkcs7->certs; p; p = p->next)
		p->seen = false;

	for (;;) {
		pr_debug("verify %s: %*phN\n",
			 x509->subject,
			 x509->raw_serial_size, x509->raw_serial);
		x509->seen = true;
		ret = x509_get_sig_params(x509);
		if (ret < 0)
			goto maybe_missing_crypto_in_x509;

		pr_debug("- issuer %s\n", x509->issuer);
		if (x509->akid_id)
			pr_debug("- authkeyid.id %*phN\n",
				 x509->akid_id->len, x509->akid_id->data);
		if (x509->akid_skid)
			pr_debug("- authkeyid.skid %*phN\n",
				 x509->akid_skid->len, x509->akid_skid->data);

		if ((!x509->akid_id && !x509->akid_skid) ||
		    strcmp(x509->subject, x509->issuer) == 0) {
			/* If there's no authority certificate specified, then
			 * the certificate must be self-signed and is the root
			 * of the chain.  Likewise if the cert is its own
			 * authority.
			 */
			pr_debug("- no auth?\n");
			if (x509->raw_subject_size != x509->raw_issuer_size ||
			    memcmp(x509->raw_subject, x509->raw_issuer,
				   x509->raw_issuer_size) != 0)
				return 0;

			ret = x509_check_signature(x509->pub, x509);
			if (ret < 0)
				goto maybe_missing_crypto_in_x509;
			x509->signer = x509;
			pr_debug("- self-signed\n");
			return 0;
		}

		/* Look through the X.509 certificates in the PKCS#7 message's
		 * list to see if the next one is there.
		 */
		auth = x509->akid_id;
		if (auth) {
			pr_debug("- want %*phN\n", auth->len, auth->data);
			for (p = pkcs7->certs; p; p = p->next) {
				pr_debug("- cmp [%u] %*phN\n",
					 p->index, p->id->len, p->id->data);
				if (asymmetric_key_id_same(p->id, auth))
					goto found_issuer_check_skid;
			}
		} else {
			auth = x509->akid_skid;
			pr_debug("- want %*phN\n", auth->len, auth->data);
			for (p = pkcs7->certs; p; p = p->next) {
				if (!p->skid)
					continue;
				pr_debug("- cmp [%u] %*phN\n",
					 p->index, p->skid->len, p->skid->data);
				if (asymmetric_key_id_same(p->skid, auth))
					goto found_issuer;
			}
		}

		/* We didn't find the root of this chain */
		pr_debug("- top\n");
		return 0;

	found_issuer_check_skid:
		/* We matched issuer + serialNumber, but if there's an
		 * authKeyId.keyId, that must match the CA subjKeyId also.
		 */
		if (x509->akid_skid &&
		    !asymmetric_key_id_same(p->skid, x509->akid_skid)) {
			pr_warn("Sig %u: X.509 chain contains auth-skid nonmatch (%u->%u)\n",
				sinfo->index, x509->index, p->index);
			return -EKEYREJECTED;
		}
	found_issuer:
		pr_debug("- subject %s\n", p->subject);
		if (p->seen) {
			pr_warn("Sig %u: X.509 chain contains loop\n",
				sinfo->index);
			return 0;
		}
		ret = x509_check_signature(p->pub, x509);
		if (ret < 0)
			return ret;
		x509->signer = p;
		if (x509 == p) {
			pr_debug("- self-signed\n");
			return 0;
		}
		x509 = p;
		might_sleep();
	}

maybe_missing_crypto_in_x509:
	/* Just prune the certificate chain at this point if we lack some
	 * crypto module to go further.  Note, however, we don't want to set
	 * sinfo->missing_crypto as the signed info block may still be
	 * validatable against an X.509 cert lower in the chain that we have a
	 * trusted copy of.
	 */
	if (ret == -ENOPKG)
		return 0;
	return ret;
}

/*
 * Verify one signed information block from a PKCS#7 message.
 */
static int pkcs7_verify_one(struct pkcs7_message *pkcs7,
			    struct pkcs7_signed_info *sinfo)
{
	int ret;

	kenter(",%u", sinfo->index);

	/* First of all, digest the data in the PKCS#7 message and the
	 * signed information block
	 */
	ret = pkcs7_digest(pkcs7, sinfo);
	if (ret < 0)
		return ret;

	/* Find the key for the signature if there is one */
	ret = pkcs7_find_key(pkcs7, sinfo);
	if (ret < 0)
		return ret;

	if (!sinfo->signer)
		return 0;

	pr_devel("Using X.509[%u] for sig %u\n",
		 sinfo->signer->index, sinfo->index);

	/* Check that the PKCS#7 signing time is valid according to the X.509
	 * certificate.  We can't, however, check against the system clock
	 * since that may not have been set yet and may be wrong.
	 */
	if (test_bit(sinfo_has_signing_time, &sinfo->aa_set)) {
		if (sinfo->signing_time < sinfo->signer->valid_from ||
		    sinfo->signing_time > sinfo->signer->valid_to) {
			pr_warn("Message signed outside of X.509 validity window\n");
			return -EKEYREJECTED;
		}
	}

	/* Verify the PKCS#7 binary against the key */
	ret = public_key_verify_signature(sinfo->signer->pub, &sinfo->sig);
	if (ret < 0)
		return ret;

	pr_devel("Verified signature %u\n", sinfo->index);

	/* Verify the internal certificate chain */
	return pkcs7_verify_sig_chain(pkcs7, sinfo);
}

/**
 * pkcs7_verify - Verify a PKCS#7 message
 * @pkcs7: The PKCS#7 message to be verified
 * @usage: The use to which the key is being put
 *
 * Verify a PKCS#7 message is internally consistent - that is, the data digest
 * matches the digest in the AuthAttrs and any signature in the message or one
 * of the X.509 certificates it carries that matches another X.509 cert in the
 * message can be verified.
 *
 * This does not look to match the contents of the PKCS#7 message against any
 * external public keys.
 *
 * Returns, in order of descending priority:
 *
 *  (*) -EKEYREJECTED if a key was selected that had a usage restriction at
 *      odds with the specified usage, or:
 *
 *  (*) -EKEYREJECTED if a signature failed to match for which we found an
 *	appropriate X.509 certificate, or:
 *
 *  (*) -EBADMSG if some part of the message was invalid, or:
 *
 *  (*) -ENOPKG if none of the signature chains are verifiable because suitable
 *	crypto modules couldn't be found, or:
 *
 *  (*) 0 if all the signature chains that don't incur -ENOPKG can be verified
 *	(note that a signature chain may be of zero length), or:
 */
int pkcs7_verify(struct pkcs7_message *pkcs7,
		 enum key_being_used_for usage)
{
	struct pkcs7_signed_info *sinfo;
	struct x509_certificate *x509;
	int enopkg = -ENOPKG;
	int ret, n;

	kenter("");

	switch (usage) {
	case VERIFYING_MODULE_SIGNATURE:
		if (pkcs7->data_type != OID_data) {
			pr_warn("Invalid module sig (not pkcs7-data)\n");
			return -EKEYREJECTED;
		}
		if (pkcs7->have_authattrs) {
			pr_warn("Invalid module sig (has authattrs)\n");
			return -EKEYREJECTED;
		}
		break;
	case VERIFYING_FIRMWARE_SIGNATURE:
		if (pkcs7->data_type != OID_data) {
			pr_warn("Invalid firmware sig (not pkcs7-data)\n");
			return -EKEYREJECTED;
		}
		if (!pkcs7->have_authattrs) {
			pr_warn("Invalid firmware sig (missing authattrs)\n");
			return -EKEYREJECTED;
		}
		break;
	case VERIFYING_KEXEC_PE_SIGNATURE:
		if (pkcs7->data_type != OID_msIndirectData) {
			pr_warn("Invalid kexec sig (not Authenticode)\n");
			return -EKEYREJECTED;
		}
		/* Authattr presence checked in parser */
		break;
	case VERIFYING_UNSPECIFIED_SIGNATURE:
		if (pkcs7->data_type != OID_data) {
			pr_warn("Invalid unspecified sig (not pkcs7-data)\n");
			return -EKEYREJECTED;
		}
		break;
	default:
		return -EINVAL;
	}

	for (n = 0, x509 = pkcs7->certs; x509; x509 = x509->next, n++) {
		ret = x509_get_sig_params(x509);
		if (ret < 0)
			return ret;
	}

	for (sinfo = pkcs7->signed_infos; sinfo; sinfo = sinfo->next) {
		ret = pkcs7_verify_one(pkcs7, sinfo);
		if (ret < 0) {
			if (ret == -ENOPKG) {
				sinfo->unsupported_crypto = true;
				continue;
			}
			kleave(" = %d", ret);
			return ret;
		}
		enopkg = 0;
	}

	kleave(" = %d", enopkg);
	return enopkg;
}
EXPORT_SYMBOL_GPL(pkcs7_verify);

/**
 * pkcs7_supply_detached_data - Supply the data needed to verify a PKCS#7 message
 * @pkcs7: The PKCS#7 message
 * @data: The data to be verified
 * @datalen: The amount of data
 *
 * Supply the detached data needed to verify a PKCS#7 message.  Note that no
 * attempt to retain/pin the data is made.  That is left to the caller.  The
 * data will not be modified by pkcs7_verify() and will not be freed when the
 * PKCS#7 message is freed.
 *
 * Returns -EINVAL if data is already supplied in the message, 0 otherwise.
 */
int pkcs7_supply_detached_data(struct pkcs7_message *pkcs7,
			       const void *data, size_t datalen)
{
	if (pkcs7->data) {
		pr_debug("Data already supplied\n");
		return -EINVAL;
	}
	pkcs7->data = data;
	pkcs7->data_len = datalen;
	return 0;
}
Commit	Line	Data
9f0d3314 DH	1	/* Verify the signature on a PKCS#7 message.
	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	#define pr_fmt(fmt) "PKCS7: "fmt
	13	#include <linux/kernel.h>
	14	#include <linux/export.h>
	15	#include <linux/slab.h>
	16	#include <linux/err.h>
	17	#include <linux/asn1.h>
	18	#include <crypto/hash.h>
db6c43bd	19	#include <crypto/public_key.h>
9f0d3314 DH	20	#include "pkcs7_parser.h"
	21
	22	/*
	23	* Digest the relevant parts of the PKCS#7 data
	24	*/
	25	static int pkcs7_digest(struct pkcs7_message *pkcs7,
	26	struct pkcs7_signed_info *sinfo)
	27	{
	28	struct crypto_shash *tfm;
	29	struct shash_desc *desc;
	30	size_t digest_size, desc_size;
	31	void *digest;
	32	int ret;
	33
4e8ae72a	34	kenter(",%u,%s", sinfo->index, sinfo->sig.hash_algo);
9f0d3314	35
4e8ae72a	36	if (!sinfo->sig.hash_algo)
9f0d3314 DH	37	return -ENOPKG;
	38
	39	/* Allocate the hashing algorithm we're going to need and find out how
	40	* big the hash operational data will be.
	41	*/
4e8ae72a	42	tfm = crypto_alloc_shash(sinfo->sig.hash_algo, 0, 0);
9f0d3314 DH	43	if (IS_ERR(tfm))
	44	return (PTR_ERR(tfm) == -ENOENT) ? -ENOPKG : PTR_ERR(tfm);
	45
	46	desc_size = crypto_shash_descsize(tfm) + sizeof(*desc);
	47	sinfo->sig.digest_size = digest_size = crypto_shash_digestsize(tfm);
	48
	49	ret = -ENOMEM;
62f57d05 SV	50	digest = kzalloc(ALIGN(digest_size, __alignof__(*desc)) + desc_size,
62f57d05 SV	51	GFP_KERNEL);
9f0d3314 DH	52	if (!digest)
	53	goto error_no_desc;
	54
62f57d05	55	desc = PTR_ALIGN(digest + digest_size, __alignof__(*desc));
9f0d3314 DH	56	desc->tfm = tfm;
	57	desc->flags = CRYPTO_TFM_REQ_MAY_SLEEP;
	58
	59	/* Digest the message [RFC2315 9.3] */
	60	ret = crypto_shash_init(desc);
	61	if (ret < 0)
	62	goto error;
	63	ret = crypto_shash_finup(desc, pkcs7->data, pkcs7->data_len, digest);
	64	if (ret < 0)
	65	goto error;
	66	pr_devel("MsgDigest = [%*ph]\n", 8, digest);
	67
	68	/* However, if there are authenticated attributes, there must be a
	69	* message digest attribute amongst them which corresponds to the
	70	* digest we just calculated.
	71	*/
99db4435	72	if (sinfo->authattrs) {
9f0d3314 DH	73	u8 tag;
9f0d3314 DH	74
99db4435 DH	75	if (!sinfo->msgdigest) {
	76	pr_warn("Sig %u: No messageDigest\n", sinfo->index);
	77	ret = -EKEYREJECTED;
	78	goto error;
	79	}
	80
9f0d3314 DH	81	if (sinfo->msgdigest_len != sinfo->sig.digest_size) {
	82	pr_debug("Sig %u: Invalid digest size (%u)\n",
	83	sinfo->index, sinfo->msgdigest_len);
	84	ret = -EBADMSG;
	85	goto error;
	86	}
	87
	88	if (memcmp(digest, sinfo->msgdigest, sinfo->msgdigest_len) != 0) {
	89	pr_debug("Sig %u: Message digest doesn't match\n",
	90	sinfo->index);
	91	ret = -EKEYREJECTED;
	92	goto error;
	93	}
	94
	95	/* We then calculate anew, using the authenticated attributes
	96	* as the contents of the digest instead. Note that we need to
	97	* convert the attributes from a CONT.0 into a SET before we
	98	* hash it.
	99	*/
	100	memset(digest, 0, sinfo->sig.digest_size);
	101
	102	ret = crypto_shash_init(desc);
	103	if (ret < 0)
	104	goto error;
	105	tag = ASN1_CONS_BIT \| ASN1_SET;
	106	ret = crypto_shash_update(desc, &tag, 1);
	107	if (ret < 0)
	108	goto error;
	109	ret = crypto_shash_finup(desc, sinfo->authattrs,
	110	sinfo->authattrs_len, digest);
	111	if (ret < 0)
	112	goto error;
	113	pr_devel("AADigest = [%*ph]\n", 8, digest);
	114	}
	115
	116	sinfo->sig.digest = digest;
	117	digest = NULL;
	118
	119	error:
	120	kfree(digest);
	121	error_no_desc:
	122	crypto_free_shash(tfm);
	123	kleave(" = %d", ret);
	124	return ret;
	125	}
	126
	127	/*
a4730357 DH	128	* Find the key (X.509 certificate) to use to verify a PKCS#7 message. PKCS#7
	129	* uses the issuer's name and the issuing certificate serial number for
	130	* matching purposes. These must match the certificate issuer's name (not
	131	* subject's name) and the certificate serial number [RFC 2315 6.7].
	132	*/
	133	static int pkcs7_find_key(struct pkcs7_message *pkcs7,
	134	struct pkcs7_signed_info *sinfo)
	135	{
	136	struct x509_certificate *x509;
	137	unsigned certix = 1;
	138
46963b77	139	kenter("%u", sinfo->index);
a4730357 DH	140
	141	for (x509 = pkcs7->certs; x509; x509 = x509->next, certix++) {
	142	/* I'm _assuming_ that the generator of the PKCS#7 message will
	143	* encode the fields from the X.509 cert in the same way in the
	144	* PKCS#7 message - but I can't be 100% sure of that. It's
	145	* possible this will need element-by-element comparison.
	146	*/
46963b77	147	if (!asymmetric_key_id_same(x509->id, sinfo->signing_cert_id))
a4730357 DH	148	continue;
	149	pr_devel("Sig %u: Found cert serial match X.509[%u]\n",
	150	sinfo->index, certix);
	151
a4730357 DH	152	if (x509->pub->pkey_algo != sinfo->sig.pkey_algo) {
	153	pr_warn("Sig %u: X.509 algo and PKCS#7 sig algo don't match\n",
	154	sinfo->index);
	155	continue;
	156	}
	157
	158	sinfo->signer = x509;
	159	return 0;
	160	}
46963b77	161
757932e6 DH	162	/* The relevant X.509 cert isn't found here, but it might be found in
	163	* the trust keyring.
	164	*/
	165	pr_debug("Sig %u: Issuing X.509 cert not found (#%*phN)\n",
	166	sinfo->index,
	167	sinfo->signing_cert_id->len, sinfo->signing_cert_id->data);
	168	return 0;
a4730357 DH	169	}
a4730357 DH	170
8c76d793 DH	171	/*
	172	* Verify the internal certificate chain as best we can.
	173	*/
	174	static int pkcs7_verify_sig_chain(struct pkcs7_message *pkcs7,
	175	struct pkcs7_signed_info *sinfo)
	176	{
	177	struct x509_certificate x509 = sinfo->signer, p;
4573b64a	178	struct asymmetric_key_id *auth;
8c76d793 DH	179	int ret;
	180
	181	kenter("");
	182
	183	for (p = pkcs7->certs; p; p = p->next)
	184	p->seen = false;
	185
	186	for (;;) {
46963b77 DH	187	pr_debug("verify %s: %*phN\n",
	188	x509->subject,
	189	x509->raw_serial_size, x509->raw_serial);
8c76d793 DH	190	x509->seen = true;
	191	ret = x509_get_sig_params(x509);
	192	if (ret < 0)
41559420	193	goto maybe_missing_crypto_in_x509;
8c76d793	194
412eccba	195	pr_debug("- issuer %s\n", x509->issuer);
4573b64a DH	196	if (x509->akid_id)
	197	pr_debug("- authkeyid.id %*phN\n",
	198	x509->akid_id->len, x509->akid_id->data);
b92e6570	199	if (x509->akid_skid)
4573b64a	200	pr_debug("- authkeyid.skid %*phN\n",
b92e6570	201	x509->akid_skid->len, x509->akid_skid->data);
8c76d793	202
4573b64a	203	if ((!x509->akid_id && !x509->akid_skid) \|\|
412eccba	204	strcmp(x509->subject, x509->issuer) == 0) {
8c76d793 DH	205	/* If there's no authority certificate specified, then
	206	* the certificate must be self-signed and is the root
	207	* of the chain. Likewise if the cert is its own
	208	* authority.
	209	*/
	210	pr_debug("- no auth?\n");
	211	if (x509->raw_subject_size != x509->raw_issuer_size \|\|
	212	memcmp(x509->raw_subject, x509->raw_issuer,
	213	x509->raw_issuer_size) != 0)
	214	return 0;
	215
	216	ret = x509_check_signature(x509->pub, x509);
	217	if (ret < 0)
41559420	218	goto maybe_missing_crypto_in_x509;
8c76d793 DH	219	x509->signer = x509;
	220	pr_debug("- self-signed\n");
	221	return 0;
	222	}
	223
	224	/* Look through the X.509 certificates in the PKCS#7 message's
	225	* list to see if the next one is there.
	226	*/
4573b64a DH	227	auth = x509->akid_id;
	228	if (auth) {
	229	pr_debug("- want %*phN\n", auth->len, auth->data);
	230	for (p = pkcs7->certs; p; p = p->next) {
	231	pr_debug("- cmp [%u] %*phN\n",
	232	p->index, p->id->len, p->id->data);
	233	if (asymmetric_key_id_same(p->id, auth))
	234	goto found_issuer_check_skid;
	235	}
	236	} else {
	237	auth = x509->akid_skid;
	238	pr_debug("- want %*phN\n", auth->len, auth->data);
	239	for (p = pkcs7->certs; p; p = p->next) {
	240	if (!p->skid)
	241	continue;
	242	pr_debug("- cmp [%u] %*phN\n",
	243	p->index, p->skid->len, p->skid->data);
	244	if (asymmetric_key_id_same(p->skid, auth))
	245	goto found_issuer;
	246	}
8c76d793 DH	247	}
	248
	249	/* We didn't find the root of this chain */
	250	pr_debug("- top\n");
	251	return 0;
	252
4573b64a DH	253	found_issuer_check_skid:
	254	/* We matched issuer + serialNumber, but if there's an
	255	* authKeyId.keyId, that must match the CA subjKeyId also.
	256	*/
	257	if (x509->akid_skid &&
	258	!asymmetric_key_id_same(p->skid, x509->akid_skid)) {
	259	pr_warn("Sig %u: X.509 chain contains auth-skid nonmatch (%u->%u)\n",
	260	sinfo->index, x509->index, p->index);
	261	return -EKEYREJECTED;
	262	}
8c76d793	263	found_issuer:
46963b77	264	pr_debug("- subject %s\n", p->subject);
8c76d793 DH	265	if (p->seen) {
	266	pr_warn("Sig %u: X.509 chain contains loop\n",
	267	sinfo->index);
	268	return 0;
	269	}
	270	ret = x509_check_signature(p->pub, x509);
	271	if (ret < 0)
	272	return ret;
	273	x509->signer = p;
	274	if (x509 == p) {
	275	pr_debug("- self-signed\n");
	276	return 0;
	277	}
	278	x509 = p;
	279	might_sleep();
	280	}
41559420 DH	281
	282	maybe_missing_crypto_in_x509:
	283	/* Just prune the certificate chain at this point if we lack some
	284	* crypto module to go further. Note, however, we don't want to set
	285	* sinfo->missing_crypto as the signed info block may still be
	286	* validatable against an X.509 cert lower in the chain that we have a
	287	* trusted copy of.
	288	*/
	289	if (ret == -ENOPKG)
	290	return 0;
	291	return ret;
8c76d793 DH	292	}
8c76d793 DH	293
9f0d3314 DH	294	/*
	295	* Verify one signed information block from a PKCS#7 message.
	296	*/
	297	static int pkcs7_verify_one(struct pkcs7_message *pkcs7,
	298	struct pkcs7_signed_info *sinfo)
	299	{
	300	int ret;
	301
	302	kenter(",%u", sinfo->index);
	303
	304	/* First of all, digest the data in the PKCS#7 message and the
	305	* signed information block
	306	*/
	307	ret = pkcs7_digest(pkcs7, sinfo);
	308	if (ret < 0)
	309	return ret;
	310
757932e6	311	/* Find the key for the signature if there is one */
a4730357 DH	312	ret = pkcs7_find_key(pkcs7, sinfo);
	313	if (ret < 0)
	314	return ret;
	315
757932e6 DH	316	if (!sinfo->signer)
	317	return 0;
	318
a4730357 DH	319	pr_devel("Using X.509[%u] for sig %u\n",
	320	sinfo->signer->index, sinfo->index);
	321
99db4435 DH	322	/* Check that the PKCS#7 signing time is valid according to the X.509
	323	* certificate. We can't, however, check against the system clock
	324	* since that may not have been set yet and may be wrong.
	325	*/
	326	if (test_bit(sinfo_has_signing_time, &sinfo->aa_set)) {
	327	if (sinfo->signing_time < sinfo->signer->valid_from \|\|
	328	sinfo->signing_time > sinfo->signer->valid_to) {
	329	pr_warn("Message signed outside of X.509 validity window\n");
	330	return -EKEYREJECTED;
	331	}
	332	}
	333
a4730357 DH	334	/* Verify the PKCS#7 binary against the key */
	335	ret = public_key_verify_signature(sinfo->signer->pub, &sinfo->sig);
	336	if (ret < 0)
	337	return ret;
	338
	339	pr_devel("Verified signature %u\n", sinfo->index);
	340
8c76d793 DH	341	/* Verify the internal certificate chain */
8c76d793 DH	342	return pkcs7_verify_sig_chain(pkcs7, sinfo);
9f0d3314 DH	343	}
	344
	345	/**
	346	* pkcs7_verify - Verify a PKCS#7 message
	347	* @pkcs7: The PKCS#7 message to be verified
99db4435	348	* @usage: The use to which the key is being put
41559420 DH	349	*
	350	* Verify a PKCS#7 message is internally consistent - that is, the data digest
	351	* matches the digest in the AuthAttrs and any signature in the message or one
	352	* of the X.509 certificates it carries that matches another X.509 cert in the
	353	* message can be verified.
	354	*
	355	* This does not look to match the contents of the PKCS#7 message against any
	356	* external public keys.
	357	*
	358	* Returns, in order of descending priority:
	359	*
99db4435 DH	360	* (*) -EKEYREJECTED if a key was selected that had a usage restriction at
	361	* odds with the specified usage, or:
	362	*
41559420 DH	363	* (*) -EKEYREJECTED if a signature failed to match for which we found an
	364	* appropriate X.509 certificate, or:
	365	*
	366	* (*) -EBADMSG if some part of the message was invalid, or:
	367	*
	368	* (*) -ENOPKG if none of the signature chains are verifiable because suitable
	369	* crypto modules couldn't be found, or:
	370	*
	371	* (*) 0 if all the signature chains that don't incur -ENOPKG can be verified
	372	* (note that a signature chain may be of zero length), or:
9f0d3314	373	*/
99db4435 DH	374	int pkcs7_verify(struct pkcs7_message *pkcs7,
99db4435 DH	375	enum key_being_used_for usage)
9f0d3314 DH	376	{
	377	struct pkcs7_signed_info *sinfo;
	378	struct x509_certificate *x509;
41559420	379	int enopkg = -ENOPKG;
9f0d3314 DH	380	int ret, n;
	381
	382	kenter("");
	383
99db4435 DH	384	switch (usage) {
	385	case VERIFYING_MODULE_SIGNATURE:
	386	if (pkcs7->data_type != OID_data) {
	387	pr_warn("Invalid module sig (not pkcs7-data)\n");
	388	return -EKEYREJECTED;
	389	}
	390	if (pkcs7->have_authattrs) {
	391	pr_warn("Invalid module sig (has authattrs)\n");
	392	return -EKEYREJECTED;
	393	}
	394	break;
	395	case VERIFYING_FIRMWARE_SIGNATURE:
	396	if (pkcs7->data_type != OID_data) {
	397	pr_warn("Invalid firmware sig (not pkcs7-data)\n");
	398	return -EKEYREJECTED;
	399	}
	400	if (!pkcs7->have_authattrs) {
	401	pr_warn("Invalid firmware sig (missing authattrs)\n");
	402	return -EKEYREJECTED;
	403	}
	404	break;
	405	case VERIFYING_KEXEC_PE_SIGNATURE:
	406	if (pkcs7->data_type != OID_msIndirectData) {
	407	pr_warn("Invalid kexec sig (not Authenticode)\n");
	408	return -EKEYREJECTED;
	409	}
	410	/* Authattr presence checked in parser */
	411	break;
	412	case VERIFYING_UNSPECIFIED_SIGNATURE:
	413	if (pkcs7->data_type != OID_data) {
	414	pr_warn("Invalid unspecified sig (not pkcs7-data)\n");
	415	return -EKEYREJECTED;
	416	}
	417	break;
	418	default:
	419	return -EINVAL;
	420	}
	421
9f0d3314 DH	422	for (n = 0, x509 = pkcs7->certs; x509; x509 = x509->next, n++) {
	423	ret = x509_get_sig_params(x509);
	424	if (ret < 0)
	425	return ret;
9f0d3314 DH	426	}
	427
	428	for (sinfo = pkcs7->signed_infos; sinfo; sinfo = sinfo->next) {
	429	ret = pkcs7_verify_one(pkcs7, sinfo);
	430	if (ret < 0) {
41559420 DH	431	if (ret == -ENOPKG) {
	432	sinfo->unsupported_crypto = true;
	433	continue;
	434	}
9f0d3314 DH	435	kleave(" = %d", ret);
	436	return ret;
	437	}
41559420	438	enopkg = 0;
9f0d3314 DH	439	}
9f0d3314 DH	440
41559420 DH	441	kleave(" = %d", enopkg);
41559420 DH	442	return enopkg;
9f0d3314 DH	443	}
9f0d3314 DH	444	EXPORT_SYMBOL_GPL(pkcs7_verify);
4ebdb76f DH	445
	446	/**
	447	* pkcs7_supply_detached_data - Supply the data needed to verify a PKCS#7 message
	448	* @pkcs7: The PKCS#7 message
	449	* @data: The data to be verified
	450	* @datalen: The amount of data
	451	*
	452	* Supply the detached data needed to verify a PKCS#7 message. Note that no
	453	* attempt to retain/pin the data is made. That is left to the caller. The
	454	* data will not be modified by pkcs7_verify() and will not be freed when the
	455	* PKCS#7 message is freed.
	456	*
	457	* Returns -EINVAL if data is already supplied in the message, 0 otherwise.
	458	*/
	459	int pkcs7_supply_detached_data(struct pkcs7_message *pkcs7,
	460	const void *data, size_t datalen)
	461	{
	462	if (pkcs7->data) {
	463	pr_debug("Data already supplied\n");
	464	return -EINVAL;
	465	}
	466	pkcs7->data = data;
	467	pkcs7->data_len = datalen;
	468	return 0;
	469	}