[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 "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,%u", sinfo->index, sinfo->sig.pkey_hash_algo);

	if (sinfo->sig.pkey_hash_algo >= PKEY_HASH__LAST ||
	    !hash_algo_name[sinfo->sig.pkey_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(hash_algo_name[sinfo->sig.pkey_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(digest_size + desc_size, GFP_KERNEL);
	if (!digest)
		goto error_no_desc;

	desc = digest + digest_size;
	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->msgdigest) {
		u8 tag;

		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);

	/* 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
 *
 * 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 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)
{
	struct pkcs7_signed_info *sinfo;
	struct x509_certificate *x509;
	int enopkg = -ENOPKG;
	int ret, n;

	kenter("");

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