Merge tag 'keys-pkcs7-20140708' into keys-next

Here's a set of changes that implement a PKCS#7 message parser in the kernel.

The PKCS#7 message parsing will then be used to limit kexec to authenticated
kernels only if so configured.

The changes provide the following facilities:

 (1) Parse an ASN.1 PKCS#7 message and pick out useful bits such as the data
     content and the X.509 certificates used to sign it and all the data
     signatures.

 (2) Verify all the data signatures against the set of X.509 certificates
     available in the message.

 (3) Follow the certificate chains and verify that:

     (a) for every self-signed X.509 certificate, check that it validly signed
     	 itself, and:

     (b) for every non-self-signed certificate, if we have a 'parent'
     	 certificate, the former is validly signed by the latter.

 (4) Look for intersections between the certificate chains and the trusted
     keyring, if any intersections are found, verify that the trusted
     certificates signed the intersection point in the chain.

 (5) For testing purposes, a key type can be made available that will take a
     PKCS#7 message, check that the message is trustworthy, and if so, add its
     data content into the key.

Note that (5) has to be altered to take account of the preparsing patches
already committed to this branch.

Signed-off-by: David Howells <dhowells@redhat.com>

11 files changed, 1302 insertions, 2 deletions

diff --git a/crypto/asymmetric_keys/Kconfig b/crypto/asymmetric_keys/Kconfig
index 03a6eb95ab5..b6df198d1b6 100644
--- a/crypto/asymmetric_keys/Kconfig
+++ b/crypto/asymmetric_keys/Kconfig
@@ -37,4 +37,26 @@ config X509_CERTIFICATE_PARSER
 	  data and provides the ability to instantiate a crypto key from a
 	  public key packet found inside the certificate.
 
+config PKCS7_MESSAGE_PARSER
+	tristate "PKCS#7 message parser"
+	depends on X509_CERTIFICATE_PARSER
+	select ASN1
+	select OID_REGISTRY
+	help
+	  This option provides support for parsing PKCS#7 format messages for
+	  signature data and provides the ability to verify the signature.
+
+config PKCS7_TEST_KEY
+	tristate "PKCS#7 testing key type"
+	depends on PKCS7_MESSAGE_PARSER
+	select SYSTEM_TRUSTED_KEYRING
+	help
+	  This option provides a type of key that can be loaded up from a
+	  PKCS#7 message - provided the message is signed by a trusted key.  If
+	  it is, the PKCS#7 wrapper is discarded and reading the key returns
+	  just the payload.  If it isn't, adding the key will fail with an
+	  error.
+
+	  This is intended for testing the PKCS#7 parser.
+
 endif # ASYMMETRIC_KEY_TYPE
diff --git a/crypto/asymmetric_keys/Makefile b/crypto/asymmetric_keys/Makefile
index 0727204aab6..92d0e9af24d 100644
--- a/crypto/asymmetric_keys/Makefile
+++ b/crypto/asymmetric_keys/Makefile
@@ -25,3 +25,25 @@ $(obj)/x509_rsakey-asn1.o: $(obj)/x509_rsakey-asn1.c $(obj)/x509_rsakey-asn1.h
 
 clean-files	+= x509-asn1.c x509-asn1.h
 clean-files	+= x509_rsakey-asn1.c x509_rsakey-asn1.h
+
+#
+# PKCS#7 message handling
+#
+obj-$(CONFIG_PKCS7_MESSAGE_PARSER) += pkcs7_message.o
+pkcs7_message-y := \
+	pkcs7-asn1.o \
+	pkcs7_parser.o \
+	pkcs7_trust.o \
+	pkcs7_verify.o
+
+$(obj)/pkcs7_parser.o: $(obj)/pkcs7-asn1.h
+$(obj)/pkcs7-asn1.o: $(obj)/pkcs7-asn1.c $(obj)/pkcs7-asn1.h
+
+clean-files	+= pkcs7-asn1.c pkcs7-asn1.h
+
+#
+# PKCS#7 parser testing key
+#
+obj-$(CONFIG_PKCS7_TEST_KEY) += pkcs7_test_key.o
+pkcs7_test_key-y := \
+	pkcs7_key_type.o
diff --git a/crypto/asymmetric_keys/pkcs7.asn1 b/crypto/asymmetric_keys/pkcs7.asn1
new file mode 100644
index 00000000000..a5a14ef28c8
--- /dev/null
+++ b/crypto/asymmetric_keys/pkcs7.asn1
@@ -0,0 +1,127 @@
+PKCS7ContentInfo ::= SEQUENCE {
+	contentType	ContentType,
+	content		[0] EXPLICIT SignedData OPTIONAL
+}
+
+ContentType ::= OBJECT IDENTIFIER ({ pkcs7_note_OID })
+
+SignedData ::= SEQUENCE {
+	version			INTEGER,
+	digestAlgorithms	DigestAlgorithmIdentifiers,
+	contentInfo		ContentInfo,
+	certificates		CHOICE {
+		certSet		[0] IMPLICIT ExtendedCertificatesAndCertificates,
+		certSequence	[2] IMPLICIT Certificates
+	} OPTIONAL ({ pkcs7_note_certificate_list }),
+	crls CHOICE {
+		crlSet		[1] IMPLICIT CertificateRevocationLists,
+		crlSequence	[3] IMPLICIT CRLSequence
+	} OPTIONAL,
+	signerInfos		SignerInfos
+}
+
+ContentInfo ::= SEQUENCE {
+	contentType	ContentType,
+	content		[0] EXPLICIT Data OPTIONAL
+}
+
+Data ::= ANY ({ pkcs7_note_data })
+
+DigestAlgorithmIdentifiers ::= CHOICE {
+	daSet			SET OF DigestAlgorithmIdentifier,
+	daSequence		SEQUENCE OF DigestAlgorithmIdentifier
+}
+
+DigestAlgorithmIdentifier ::= SEQUENCE {
+	algorithm   OBJECT IDENTIFIER ({ pkcs7_note_OID }),
+	parameters  ANY OPTIONAL
+}
+
+--
+-- Certificates and certificate lists
+--
+ExtendedCertificatesAndCertificates ::= SET OF ExtendedCertificateOrCertificate
+
+ExtendedCertificateOrCertificate ::= CHOICE {
+  certificate		Certificate,				-- X.509
+  extendedCertificate	[0] IMPLICIT ExtendedCertificate	-- PKCS#6
+}
+
+ExtendedCertificate ::= Certificate -- cheating
+
+Certificates ::= SEQUENCE OF Certificate
+
+CertificateRevocationLists ::= SET OF CertificateList
+
+CertificateList ::= SEQUENCE OF Certificate -- This may be defined incorrectly
+
+CRLSequence ::= SEQUENCE OF CertificateList
+
+Certificate ::= ANY ({ pkcs7_extract_cert }) -- X.509
+
+--
+-- Signer information
+--
+SignerInfos ::= CHOICE {
+	siSet		SET OF SignerInfo,
+	siSequence	SEQUENCE OF SignerInfo
+}
+
+SignerInfo ::= SEQUENCE {
+	version			INTEGER,
+	issuerAndSerialNumber	IssuerAndSerialNumber,
+	digestAlgorithm		DigestAlgorithmIdentifier ({ pkcs7_sig_note_digest_algo }),
+	authenticatedAttributes	CHOICE {
+		aaSet		[0] IMPLICIT SetOfAuthenticatedAttribute
+					({ pkcs7_sig_note_set_of_authattrs }),
+		aaSequence	[2] EXPLICIT SEQUENCE OF AuthenticatedAttribute
+			-- Explicit because easier to compute digest on
+			-- sequence of attributes and then reuse encoded
+			-- sequence in aaSequence.
+	} OPTIONAL,
+	digestEncryptionAlgorithm
+				DigestEncryptionAlgorithmIdentifier ({ pkcs7_sig_note_pkey_algo }),
+	encryptedDigest		EncryptedDigest,
+	unauthenticatedAttributes CHOICE {
+		uaSet		[1] IMPLICIT SET OF UnauthenticatedAttribute,
+		uaSequence	[3] IMPLICIT SEQUENCE OF UnauthenticatedAttribute
+	} OPTIONAL
+} ({ pkcs7_note_signed_info })
+
+IssuerAndSerialNumber ::= SEQUENCE {
+	issuer			Name ({ pkcs7_sig_note_issuer }),
+	serialNumber		CertificateSerialNumber ({ pkcs7_sig_note_serial })
+}
+
+CertificateSerialNumber ::= INTEGER
+
+SetOfAuthenticatedAttribute ::= SET OF AuthenticatedAttribute
+
+AuthenticatedAttribute ::= SEQUENCE {
+	type			OBJECT IDENTIFIER ({ pkcs7_note_OID }),
+	values			SET OF ANY ({ pkcs7_sig_note_authenticated_attr })
+}
+
+UnauthenticatedAttribute ::= SEQUENCE {
+	type			OBJECT IDENTIFIER ({ pkcs7_note_OID }),
+	values			SET OF ANY
+}
+
+DigestEncryptionAlgorithmIdentifier ::= SEQUENCE {
+	algorithm		OBJECT IDENTIFIER ({ pkcs7_note_OID }),
+	parameters		ANY OPTIONAL
+}
+
+EncryptedDigest ::= OCTET STRING ({ pkcs7_sig_note_signature })
+
+---
+--- X.500 Name
+---
+Name ::= SEQUENCE OF RelativeDistinguishedName
+
+RelativeDistinguishedName ::= SET OF AttributeValueAssertion
+
+AttributeValueAssertion ::= SEQUENCE {
+	attributeType		OBJECT IDENTIFIER ({ pkcs7_note_OID }),
+	attributeValue		ANY
+}
diff --git a/crypto/asymmetric_keys/pkcs7_key_type.c b/crypto/asymmetric_keys/pkcs7_key_type.c
new file mode 100644
index 00000000000..c2091f7bd15
--- /dev/null
+++ b/crypto/asymmetric_keys/pkcs7_key_type.c
@@ -0,0 +1,99 @@
+/* Testing module to load key from trusted PKCS#7 message
+ *
+ * Copyright (C) 2014 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) "PKCS7key: "fmt
+#include <linux/key.h>
+#include <linux/key-type.h>
+#include <crypto/pkcs7.h>
+#include <keys/user-type.h>
+#include <keys/system_keyring.h>
+#include "pkcs7_parser.h"
+
+/*
+ * Preparse a PKCS#7 wrapped and validated data blob.
+ */
+static int pkcs7_preparse(struct key_preparsed_payload *prep)
+{
+	struct pkcs7_message *pkcs7;
+	const void *data, *saved_prep_data;
+	size_t datalen, saved_prep_datalen;
+	bool trusted;
+	int ret;
+
+	kenter("");
+
+	saved_prep_data = prep->data;
+	saved_prep_datalen = prep->datalen;
+	pkcs7 = pkcs7_parse_message(saved_prep_data, saved_prep_datalen);
+	if (IS_ERR(pkcs7)) {
+		ret = PTR_ERR(pkcs7);
+		goto error;
+	}
+
+	ret = pkcs7_verify(pkcs7);
+	if (ret < 0)
+		goto error_free;
+
+	ret = pkcs7_validate_trust(pkcs7, system_trusted_keyring, &trusted);
+	if (ret < 0)
+		goto error_free;
+	if (!trusted)
+		pr_warn("PKCS#7 message doesn't chain back to a trusted key\n");
+
+	ret = pkcs7_get_content_data(pkcs7, &data, &datalen, false);
+	if (ret < 0)
+		goto error_free;
+
+	prep->data = data;
+	prep->datalen = datalen;
+	ret = user_preparse(prep);
+	prep->data = saved_prep_data;
+	prep->datalen = saved_prep_datalen;
+
+error_free:
+	pkcs7_free_message(pkcs7);
+error:
+	kleave(" = %d", ret);
+	return ret;
+}
+
+/*
+ * user defined keys take an arbitrary string as the description and an
+ * arbitrary blob of data as the payload
+ */
+struct key_type key_type_pkcs7 = {
+	.name			= "pkcs7_test",
+	.def_lookup_type	= KEYRING_SEARCH_LOOKUP_DIRECT,
+	.preparse		= pkcs7_preparse,
+	.free_preparse		= user_free_preparse,
+	.instantiate		= generic_key_instantiate,
+	.match			= user_match,
+	.revoke			= user_revoke,
+	.destroy		= user_destroy,
+	.describe		= user_describe,
+	.read			= user_read,
+};
+
+/*
+ * Module stuff
+ */
+static int __init pkcs7_key_init(void)
+{
+	return register_key_type(&key_type_pkcs7);
+}
+
+static void __exit pkcs7_key_cleanup(void)
+{
+	unregister_key_type(&key_type_pkcs7);
+}
+
+module_init(pkcs7_key_init);
+module_exit(pkcs7_key_cleanup);
diff --git a/crypto/asymmetric_keys/pkcs7_parser.c b/crypto/asymmetric_keys/pkcs7_parser.c
new file mode 100644
index 00000000000..42e56aa7d27
--- /dev/null
+++ b/crypto/asymmetric_keys/pkcs7_parser.c
@@ -0,0 +1,396 @@
+/* PKCS#7 parser
+ *
+ * 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/oid_registry.h>
+#include "public_key.h"
+#include "pkcs7_parser.h"
+#include "pkcs7-asn1.h"
+
+struct pkcs7_parse_context {
+	struct pkcs7_message	*msg;		/* Message being constructed */
+	struct pkcs7_signed_info *sinfo;	/* SignedInfo being constructed */
+	struct pkcs7_signed_info **ppsinfo;
+	struct x509_certificate *certs;		/* Certificate cache */
+	struct x509_certificate **ppcerts;
+	unsigned long	data;			/* Start of data */
+	enum OID	last_oid;		/* Last OID encountered */
+	unsigned	x509_index;
+	unsigned	sinfo_index;
+};
+
+/**
+ * pkcs7_free_message - Free a PKCS#7 message
+ * @pkcs7: The PKCS#7 message to free
+ */
+void pkcs7_free_message(struct pkcs7_message *pkcs7)
+{
+	struct x509_certificate *cert;
+	struct pkcs7_signed_info *sinfo;
+
+	if (pkcs7) {
+		while (pkcs7->certs) {
+			cert = pkcs7->certs;
+			pkcs7->certs = cert->next;
+			x509_free_certificate(cert);
+		}
+		while (pkcs7->crl) {
+			cert = pkcs7->crl;
+			pkcs7->crl = cert->next;
+			x509_free_certificate(cert);
+		}
+		while (pkcs7->signed_infos) {
+			sinfo = pkcs7->signed_infos;
+			pkcs7->signed_infos = sinfo->next;
+			mpi_free(sinfo->sig.mpi[0]);
+			kfree(sinfo->sig.digest);
+			kfree(sinfo);
+		}
+		kfree(pkcs7);
+	}
+}
+EXPORT_SYMBOL_GPL(pkcs7_free_message);
+
+/**
+ * pkcs7_parse_message - Parse a PKCS#7 message
+ * @data: The raw binary ASN.1 encoded message to be parsed
+ * @datalen: The size of the encoded message
+ */
+struct pkcs7_message *pkcs7_parse_message(const void *data, size_t datalen)
+{
+	struct pkcs7_parse_context *ctx;
+	struct pkcs7_message *msg;
+	long ret;
+
+	ret = -ENOMEM;
+	msg = kzalloc(sizeof(struct pkcs7_message), GFP_KERNEL);
+	if (!msg)
+		goto error_no_sig;
+	ctx = kzalloc(sizeof(struct pkcs7_parse_context), GFP_KERNEL);
+	if (!ctx)
+		goto error_no_ctx;
+	ctx->sinfo = kzalloc(sizeof(struct pkcs7_signed_info), GFP_KERNEL);
+	if (!ctx->sinfo)
+		goto error_no_sinfo;
+
+	ctx->msg = msg;
+	ctx->data = (unsigned long)data;
+	ctx->ppcerts = &ctx->certs;
+	ctx->ppsinfo = &ctx->msg->signed_infos;
+
+	/* Attempt to decode the signature */
+	ret = asn1_ber_decoder(&pkcs7_decoder, ctx, data, datalen);
+	if (ret < 0)
+		goto error_decode;
+
+	while (ctx->certs) {
+		struct x509_certificate *cert = ctx->certs;
+		ctx->certs = cert->next;
+		x509_free_certificate(cert);
+	}
+	mpi_free(ctx->sinfo->sig.mpi[0]);
+	kfree(ctx->sinfo->sig.digest);
+	kfree(ctx->sinfo);
+	kfree(ctx);
+	return msg;
+
+error_decode:
+	mpi_free(ctx->sinfo->sig.mpi[0]);
+	kfree(ctx->sinfo->sig.digest);
+	kfree(ctx->sinfo);
+error_no_sinfo:
+	kfree(ctx);
+error_no_ctx:
+	pkcs7_free_message(msg);
+error_no_sig:
+	return ERR_PTR(ret);
+}
+EXPORT_SYMBOL_GPL(pkcs7_parse_message);
+
+/**
+ * pkcs7_get_content_data - Get access to the PKCS#7 content
+ * @pkcs7: The preparsed PKCS#7 message to access
+ * @_data: Place to return a pointer to the data
+ * @_data_len: Place to return the data length
+ * @want_wrapper: True if the ASN.1 object header should be included in the data
+ *
+ * Get access to the data content of the PKCS#7 message, including, optionally,
+ * the header of the ASN.1 object that contains it.  Returns -ENODATA if the
+ * data object was missing from the message.
+ */
+int pkcs7_get_content_data(const struct pkcs7_message *pkcs7,
+			   const void **_data, size_t *_data_len,
+			   bool want_wrapper)
+{
+	size_t wrapper;
+
+	if (!pkcs7->data)
+		return -ENODATA;
+
+	wrapper = want_wrapper ? pkcs7->data_hdrlen : 0;
+	*_data = pkcs7->data - wrapper;
+	*_data_len = pkcs7->data_len + wrapper;
+	return 0;
+}
+EXPORT_SYMBOL_GPL(pkcs7_get_content_data);
+
+/*
+ * Note an OID when we find one for later processing when we know how
+ * to interpret it.
+ */
+int pkcs7_note_OID(void *context, size_t hdrlen,
+		   unsigned char tag,
+		   const void *value, size_t vlen)
+{
+	struct pkcs7_parse_context *ctx = context;
+
+	ctx->last_oid = look_up_OID(value, vlen);
+	if (ctx->last_oid == OID__NR) {
+		char buffer[50];
+		sprint_oid(value, vlen, buffer, sizeof(buffer));
+		printk("PKCS7: Unknown OID: [%lu] %s\n",
+		       (unsigned long)value - ctx->data, buffer);
+	}
+	return 0;
+}
+
+/*
+ * Note the digest algorithm for the signature.
+ */
+int pkcs7_sig_note_digest_algo(void *context, size_t hdrlen,
+			       unsigned char tag,
+			       const void *value, size_t vlen)
+{
+	struct pkcs7_parse_context *ctx = context;
+
+	switch (ctx->last_oid) {
+	case OID_md4:
+		ctx->sinfo->sig.pkey_hash_algo = HASH_ALGO_MD4;
+		break;
+	case OID_md5:
+		ctx->sinfo->sig.pkey_hash_algo = HASH_ALGO_MD5;
+		break;
+	case OID_sha1:
+		ctx->sinfo->sig.pkey_hash_algo = HASH_ALGO_SHA1;
+		break;
+	case OID_sha256:
+		ctx->sinfo->sig.pkey_hash_algo = HASH_ALGO_SHA256;
+		break;
+	default:
+		printk("Unsupported digest algo: %u\n", ctx->last_oid);
+		return -ENOPKG;
+	}
+	return 0;
+}
+
+/*
+ * Note the public key algorithm for the signature.
+ */
+int pkcs7_sig_note_pkey_algo(void *context, size_t hdrlen,
+			     unsigned char tag,
+			     const void *value, size_t vlen)
+{
+	struct pkcs7_parse_context *ctx = context;
+
+	switch (ctx->last_oid) {
+	case OID_rsaEncryption:
+		ctx->sinfo->sig.pkey_algo = PKEY_ALGO_RSA;
+		break;
+	default:
+		printk("Unsupported pkey algo: %u\n", ctx->last_oid);
+		return -ENOPKG;
+	}
+	return 0;
+}
+
+/*
+ * Extract a certificate and store it in the context.
+ */
+int pkcs7_extract_cert(void *context, size_t hdrlen,
+		       unsigned char tag,
+		       const void *value, size_t vlen)
+{
+	struct pkcs7_parse_context *ctx = context;
+	struct x509_certificate *x509;
+
+	if (tag != ((ASN1_UNIV << 6) | ASN1_CONS_BIT | ASN1_SEQ)) {
+		pr_debug("Cert began with tag %02x at %lu\n",
+			 tag, (unsigned long)ctx - ctx->data);
+		return -EBADMSG;
+	}
+
+	/* We have to correct for the header so that the X.509 parser can start
+	 * from the beginning.  Note that since X.509 stipulates DER, there
+	 * probably shouldn't be an EOC trailer - but it is in PKCS#7 (which
+	 * stipulates BER).
+	 */
+	value -= hdrlen;
+	vlen += hdrlen;
+
+	if (((u8*)value)[1] == 0x80)
+		vlen += 2; /* Indefinite length - there should be an EOC */
+
+	x509 = x509_cert_parse(value, vlen);
+	if (IS_ERR(x509))
+		return PTR_ERR(x509);
+
+	pr_debug("Got cert for %s\n", x509->subject);
+	pr_debug("- fingerprint %s\n", x509->fingerprint);
+
+	x509->index = ++ctx->x509_index;
+	*ctx->ppcerts = x509;
+	ctx->ppcerts = &x509->next;
+	return 0;
+}
+
+/*
+ * Save the certificate list
+ */
+int pkcs7_note_certificate_list(void *context, size_t hdrlen,
+				unsigned char tag,
+				const void *value, size_t vlen)
+{
+	struct pkcs7_parse_context *ctx = context;
+
+	pr_devel("Got cert list (%02x)\n", tag);
+
+	*ctx->ppcerts = ctx->msg->certs;
+	ctx->msg->certs = ctx->certs;
+	ctx->certs = NULL;
+	ctx->ppcerts = &ctx->certs;
+	return 0;
+}
+
+/*
+ * Extract the data from the message and store that and its content type OID in
+ * the context.
+ */
+int pkcs7_note_data(void *context, size_t hdrlen,
+		    unsigned char tag,
+		    const void *value, size_t vlen)
+{
+	struct pkcs7_parse_context *ctx = context;
+
+	pr_debug("Got data\n");
+
+	ctx->msg->data = value;
+	ctx->msg->data_len = vlen;
+	ctx->msg->data_hdrlen = hdrlen;
+	ctx->msg->data_type = ctx->last_oid;
+	return 0;
+}
+
+/*
+ * Parse authenticated attributes
+ */
+int pkcs7_sig_note_authenticated_attr(void *context, size_t hdrlen,
+				      unsigned char tag,
+				      const void *value, size_t vlen)
+{
+	struct pkcs7_parse_context *ctx = context;
+
+	pr_devel("AuthAttr: %02x %zu [%*ph]\n", tag, vlen, (unsigned)vlen, value);
+
+	switch (ctx->last_oid) {
+	case OID_messageDigest:
+		if (tag != ASN1_OTS)
+			return -EBADMSG;
+		ctx->sinfo->msgdigest = value;
+		ctx->sinfo->msgdigest_len = vlen;
+		return 0;
+	default:
+		return 0;
+	}
+}
+
+/*
+ * Note the set of auth attributes for digestion purposes [RFC2315 9.3]
+ */
+int pkcs7_sig_note_set_of_authattrs(void *context, size_t hdrlen,
+				    unsigned char tag,
+				    const void *value, size_t vlen)
+{
+	struct pkcs7_parse_context *ctx = context;
+
+	/* We need to switch the 'CONT 0' to a 'SET OF' when we digest */
+	ctx->sinfo->authattrs = value - (hdrlen - 1);
+	ctx->sinfo->authattrs_len = vlen + (hdrlen - 1);
+	return 0;
+}
+
+/*
+ * Note the issuing certificate serial number
+ */
+int pkcs7_sig_note_serial(void *context, size_t hdrlen,
+			  unsigned char tag,
+			  const void *value, size_t vlen)
+{
+	struct pkcs7_parse_context *ctx = context;
+	ctx->sinfo->raw_serial = value;
+	ctx->sinfo->raw_serial_size = vlen;
+	return 0;
+}
+
+/*
+ * Note the issuer's name
+ */
+int pkcs7_sig_note_issuer(void *context, size_t hdrlen,
+			  unsigned char tag,
+			  const void *value, size_t vlen)
+{
+	struct pkcs7_parse_context *ctx = context;
+	ctx->sinfo->raw_issuer = value;
+	ctx->sinfo->raw_issuer_size = vlen;
+	return 0;
+}
+
+/*
+ * Note the signature data
+ */
+int pkcs7_sig_note_signature(void *context, size_t hdrlen,
+			     unsigned char tag,
+			     const void *value, size_t vlen)
+{
+	struct pkcs7_parse_context *ctx = context;
+	MPI mpi;
+
+	BUG_ON(ctx->sinfo->sig.pkey_algo != PKEY_ALGO_RSA);
+
+	mpi = mpi_read_raw_data(value, vlen);
+	if (!mpi)
+		return -ENOMEM;
+
+	ctx->sinfo->sig.mpi[0] = mpi;
+	ctx->sinfo->sig.nr_mpi = 1;
+	return 0;
+}
+
+/*
+ * Note a signature information block
+ */
+int pkcs7_note_signed_info(void *context, size_t hdrlen,
+			   unsigned char tag,
+			   const void *value, size_t vlen)
+{
+	struct pkcs7_parse_context *ctx = context;
+
+	ctx->sinfo->index = ++ctx->sinfo_index;
+	*ctx->ppsinfo = ctx->sinfo;
+	ctx->ppsinfo = &ctx->sinfo->next;
+	ctx->sinfo = kzalloc(sizeof(struct pkcs7_signed_info), GFP_KERNEL);
+	if (!ctx->sinfo)
+		return -ENOMEM;
+	return 0;
+}
diff --git a/crypto/asymmetric_keys/pkcs7_parser.h b/crypto/asymmetric_keys/pkcs7_parser.h
new file mode 100644
index 00000000000..d25f4d15370
--- /dev/null
+++ b/crypto/asymmetric_keys/pkcs7_parser.h
@@ -0,0 +1,61 @@
+/* PKCS#7 crypto data parser internal definitions
+ *
+ * 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/oid_registry.h>
+#include <crypto/pkcs7.h>
+#include "x509_parser.h"
+
+#define kenter(FMT, ...) \
+	pr_devel("==> %s("FMT")\n", __func__, ##__VA_ARGS__)
+#define kleave(FMT, ...) \
+	pr_devel("<== %s()"FMT"\n", __func__, ##__VA_ARGS__)
+
+struct pkcs7_signed_info {
+	struct pkcs7_signed_info *next;
+	struct x509_certificate *signer; /* Signing certificate (in msg->certs) */
+	unsigned index;
+	bool trusted;
+
+	/* Message digest - the digest of the Content Data (or NULL) */
+	const void	*msgdigest;
+	unsigned	msgdigest_len;
+
+	/* Authenticated Attribute data (or NULL) */
+	unsigned	authattrs_len;
+	const void	*authattrs;
+
+	/* Issuing cert serial number and issuer's name */
+	const void	*raw_serial;
+	unsigned	raw_serial_size;
+	unsigned	raw_issuer_size;
+	const void	*raw_issuer;
+
+	/* Message signature.
+	 *
+	 * This contains the generated digest of _either_ the Content Data or
+	 * the Authenticated Attributes [RFC2315 9.3].  If the latter, one of
+	 * the attributes contains the digest of the the Content Data within
+	 * it.
+	 */
+	struct public_key_signature sig;
+};
+
+struct pkcs7_message {
+	struct x509_certificate *certs;	/* Certificate list */
+	struct x509_certificate *crl;	/* Revocation list */
+	struct pkcs7_signed_info *signed_infos;
+
+	/* Content Data (or NULL) */
+	enum OID	data_type;	/* Type of Data */
+	size_t		data_len;	/* Length of Data */
+	size_t		data_hdrlen;	/* Length of Data ASN.1 header */
+	const void	*data;		/* Content Data (or 0) */
+};
diff --git a/crypto/asymmetric_keys/pkcs7_trust.c b/crypto/asymmetric_keys/pkcs7_trust.c
new file mode 100644
index 00000000000..b6b04513140
--- /dev/null
+++ b/crypto/asymmetric_keys/pkcs7_trust.c
@@ -0,0 +1,219 @@
+/* Validate the trust chain of 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 <linux/key.h>
+#include <keys/asymmetric-type.h>
+#include "public_key.h"
+#include "pkcs7_parser.h"
+
+/*
+ * Request an asymmetric key.
+ */
+static struct key *pkcs7_request_asymmetric_key(
+	struct key *keyring,
+	const char *signer, size_t signer_len,
+	const char *authority, size_t auth_len)
+{
+	key_ref_t key;
+	char *id;
+
+	kenter(",%zu,,%zu", signer_len, auth_len);
+
+	/* Construct an identifier. */
+	id = kmalloc(signer_len + 2 + auth_len + 1, GFP_KERNEL);
+	if (!id)
+		return ERR_PTR(-ENOMEM);
+
+	memcpy(id, signer, signer_len);
+	id[signer_len + 0] = ':';
+	id[signer_len + 1] = ' ';
+	memcpy(id + signer_len + 2, authority, auth_len);
+	id[signer_len + 2 + auth_len] = 0;
+
+	pr_debug("Look up: \"%s\"\n", id);
+
+	key = keyring_search(make_key_ref(keyring, 1),
+			     &key_type_asymmetric, id);
+	if (IS_ERR(key))
+		pr_debug("Request for module key '%s' err %ld\n",
+			 id, PTR_ERR(key));
+	kfree(id);
+
+	if (IS_ERR(key)) {
+		switch (PTR_ERR(key)) {
+			/* Hide some search errors */
+		case -EACCES:
+		case -ENOTDIR:
+		case -EAGAIN:
+			return ERR_PTR(-ENOKEY);
+		default:
+			return ERR_CAST(key);
+		}
+	}
+
+	pr_devel("<==%s() = 0 [%x]\n", __func__, key_serial(key_ref_to_ptr(key)));
+	return key_ref_to_ptr(key);
+}
+
+/**
+ * Check the trust on one PKCS#7 SignedInfo block.
+ */
+int pkcs7_validate_trust_one(struct pkcs7_message *pkcs7,
+			     struct pkcs7_signed_info *sinfo,
+			     struct key *trust_keyring)
+{
+	struct public_key_signature *sig = &sinfo->sig;
+	struct x509_certificate *x509, *last = NULL, *p;
+	struct key *key;
+	bool trusted;
+	int ret;
+
+	kenter(",%u,", sinfo->index);
+
+	for (x509 = sinfo->signer; x509; x509 = x509->signer) {
+		if (x509->seen) {
+			if (x509->verified) {
+				trusted = x509->trusted;
+				goto verified;
+			}
+			kleave(" = -ENOKEY [cached]");
+			return -ENOKEY;
+		}
+		x509->seen = true;
+
+		/* Look to see if this certificate is present in the trusted
+		 * keys.
+		 */
+		key = pkcs7_request_asymmetric_key(
+			trust_keyring,
+			x509->subject, strlen(x509->subject),
+			x509->fingerprint, strlen(x509->fingerprint));
+		if (!IS_ERR(key))
+			/* One of the X.509 certificates in the PKCS#7 message
+			 * is apparently the same as one we already trust.
+			 * Verify that the trusted variant can also validate
+			 * the signature on the descendant.
+			 */
+			goto matched;
+		if (key == ERR_PTR(-ENOMEM))
+			return -ENOMEM;
+
+		 /* Self-signed certificates form roots of their own, and if we
+		  * don't know them, then we can't accept them.
+		  */
+		if (x509->next == x509) {
+			kleave(" = -ENOKEY [unknown self-signed]");
+			return -ENOKEY;
+		}
+
+		might_sleep();
+		last = x509;
+		sig = &last->sig;
+	}
+
+	/* No match - see if the root certificate has a signer amongst the
+	 * trusted keys.
+	 */
+	if (!last || !last->issuer || !last->authority) {
+		kleave(" = -ENOKEY [no backref]");
+		return -ENOKEY;
+	}
+
+	key = pkcs7_request_asymmetric_key(
+		trust_keyring,
+		last->issuer, strlen(last->issuer),
+		last->authority, strlen(last->authority));
+	if (IS_ERR(key))
+		return PTR_ERR(key) == -ENOMEM ? -ENOMEM : -ENOKEY;
+	x509 = last;
+
+matched:
+	ret = verify_signature(key, sig);
+	trusted = test_bit(KEY_FLAG_TRUSTED, &key->flags);
+	key_put(key);
+	if (ret < 0) {
+		if (ret == -ENOMEM)
+			return ret;
+		kleave(" = -EKEYREJECTED [verify %d]", ret);
+		return -EKEYREJECTED;
+	}
+
+verified:
+	x509->verified = true;
+	for (p = sinfo->signer; p != x509; p = p->signer) {
+		p->verified = true;
+		p->trusted = trusted;
+	}
+	sinfo->trusted = trusted;
+	kleave(" = 0");
+	return 0;
+}
+
+/**
+ * pkcs7_validate_trust - Validate PKCS#7 trust chain
+ * @pkcs7: The PKCS#7 certificate to validate
+ * @trust_keyring: Signing certificates to use as starting points
+ * @_trusted: Set to true if trustworth, false otherwise
+ *
+ * Validate that the certificate chain inside the PKCS#7 message intersects
+ * keys we already know and trust.
+ *
+ * Returns, in order of descending priority:
+ *
+ *  (*) -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:
+ *
+ *  (*) -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 pkcs7_validate_trust(struct pkcs7_message *pkcs7,
+			 struct key *trust_keyring,
+			 bool *_trusted)
+{
+	struct pkcs7_signed_info *sinfo;
+	struct x509_certificate *p;
+	int cached_ret = 0, ret;
+
+	for (p = pkcs7->certs; p; p = p->next)
+		p->seen = false;
+
+	for (sinfo = pkcs7->signed_infos; sinfo; sinfo = sinfo->next) {
+		ret = pkcs7_validate_trust_one(pkcs7, sinfo, trust_keyring);
+		if (ret < 0) {
+			if (ret == -ENOPKG) {
+				cached_ret = -ENOPKG;
+			} else if (ret == -ENOKEY) {
+				if (cached_ret == 0)
+					cached_ret = -ENOKEY;
+			} else {
+				return ret;
+			}
+		}
+		*_trusted |= sinfo->trusted;
+	}
+
+	return cached_ret;
+}
+EXPORT_SYMBOL_GPL(pkcs7_validate_trust);
diff --git a/crypto/asymmetric_keys/pkcs7_verify.c b/crypto/asymmetric_keys/pkcs7_verify.c
new file mode 100644
index 00000000000..51ff36f3a91
--- /dev/null
+++ b/crypto/asymmetric_keys/pkcs7_verify.c
@@ -0,0 +1,323 @@
+/* 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,%u,%u",
+	       sinfo->index, sinfo->raw_serial_size, sinfo->raw_issuer_size);
+
+	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 (x509->raw_serial_size != sinfo->raw_serial_size ||
+		    memcmp(x509->raw_serial, sinfo->raw_serial,
+			   sinfo->raw_serial_size) != 0)
+			continue;
+		pr_devel("Sig %u: Found cert serial match X.509[%u]\n",
+			 sinfo->index, certix);
+
+		if (x509->raw_issuer_size != sinfo->raw_issuer_size ||
+		    memcmp(x509->raw_issuer, sinfo->raw_issuer,
+			   sinfo->raw_issuer_size) != 0) {
+			pr_warn("Sig %u: X.509 subject and PKCS#7 issuer don't match\n",
+				sinfo->index);
+			continue;
+		}
+
+		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;
+	}
+	pr_warn("Sig %u: Issuing X.509 cert not found (#%*ph)\n",
+		sinfo->index, sinfo->raw_serial_size, sinfo->raw_serial);
+	return -ENOKEY;
+}
+
+/*
+ * 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;
+	int ret;
+
+	kenter("");
+
+	for (p = pkcs7->certs; p; p = p->next)
+		p->seen = false;
+
+	for (;;) {
+		pr_debug("verify %s: %s\n", x509->subject, x509->fingerprint);
+		x509->seen = true;
+		ret = x509_get_sig_params(x509);
+		if (ret < 0)
+			return ret;
+
+		if (x509->issuer)
+			pr_debug("- issuer %s\n", x509->issuer);
+		if (x509->authority)
+			pr_debug("- authkeyid %s\n", x509->authority);
+
+		if (!x509->authority ||
+		    (x509->subject &&
+		     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)
+				return ret;
+			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.
+		 */
+		pr_debug("- want %s\n", x509->authority);
+		for (p = pkcs7->certs; p; p = p->next) {
+			pr_debug("- cmp [%u] %s\n", p->index, p->fingerprint);
+			if (p->raw_subject_size == x509->raw_issuer_size &&
+			    strcmp(p->fingerprint, x509->authority) == 0 &&
+			    memcmp(p->raw_subject, x509->raw_issuer,
+				   x509->raw_issuer_size) == 0)
+				goto found_issuer;
+		}
+
+		/* We didn't find the root of this chain */
+		pr_debug("- top\n");
+		return 0;
+
+	found_issuer:
+		pr_debug("- issuer %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();
+	}
+}
+
+/*
+ * 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 */
+	ret = pkcs7_find_key(pkcs7, sinfo);
+	if (ret < 0)
+		return ret;
+
+	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
+ */
+int pkcs7_verify(struct pkcs7_message *pkcs7)
+{
+	struct pkcs7_signed_info *sinfo;
+	struct x509_certificate *x509;
+	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;
+		pr_debug("X.509[%u] %s\n", n, x509->authority);
+	}
+
+	for (sinfo = pkcs7->signed_infos; sinfo; sinfo = sinfo->next) {
+		ret = pkcs7_verify_one(pkcs7, sinfo);
+		if (ret < 0) {
+			kleave(" = %d", ret);
+			return ret;
+		}
+	}
+
+	kleave(" = 0");
+	return 0;
+}
+EXPORT_SYMBOL_GPL(pkcs7_verify);
diff --git a/crypto/asymmetric_keys/x509.asn1 b/crypto/asymmetric_keys/x509.asn1
index bf32b3dff08..aae0cde414e 100644
--- a/crypto/asymmetric_keys/x509.asn1
+++ b/crypto/asymmetric_keys/x509.asn1
@@ -6,7 +6,7 @@ Certificate ::= SEQUENCE {
 
 TBSCertificate ::= SEQUENCE {
 	version           [ 0 ]	Version DEFAULT,
-	serialNumber		CertificateSerialNumber,
+	serialNumber		CertificateSerialNumber ({ x509_note_serial }),
 	signature		AlgorithmIdentifier ({ x509_note_pkey_algo }),
 	issuer			Name ({ x509_note_issuer }),
 	validity		Validity,
diff --git a/crypto/asymmetric_keys/x509_cert_parser.c b/crypto/asymmetric_keys/x509_cert_parser.c
index 29893162497..ac72348c186 100644
--- a/crypto/asymmetric_keys/x509_cert_parser.c
+++ b/crypto/asymmetric_keys/x509_cert_parser.c
@@ -11,6 +11,7 @@
 
 #define pr_fmt(fmt) "X.509: "fmt
 #include <linux/kernel.h>
+#include <linux/export.h>
 #include <linux/slab.h>
 #include <linux/err.h>
 #include <linux/oid_registry.h>
@@ -52,6 +53,7 @@ void x509_free_certificate(struct x509_certificate *cert)
 		kfree(cert);
 	}
 }
+EXPORT_SYMBOL_GPL(x509_free_certificate);
 
 /*
  * Parse an X.509 certificate
@@ -97,6 +99,7 @@ error_no_ctx:
 error_no_cert:
 	return ERR_PTR(ret);
 }
+EXPORT_SYMBOL_GPL(x509_cert_parse);
 
 /*
  * Note an OID when we find one for later processing when we know how
@@ -211,6 +214,19 @@ int x509_note_signature(void *context, size_t hdrlen,
 }
 
 /*
+ * Note the certificate serial number
+ */
+int x509_note_serial(void *context, size_t hdrlen,
+		     unsigned char tag,
+		     const void *value, size_t vlen)
+{
+	struct x509_parse_context *ctx = context;
+	ctx->cert->raw_serial = value;
+	ctx->cert->raw_serial_size = vlen;
+	return 0;
+}
+
+/*
  * Note some of the name segments from which we'll fabricate a name.
  */
 int x509_extract_name_segment(void *context, size_t hdrlen,
@@ -322,6 +338,8 @@ int x509_note_issuer(void *context, size_t hdrlen,
 		     const void *value, size_t vlen)
 {
 	struct x509_parse_context *ctx = context;
+	ctx->cert->raw_issuer = value;
+	ctx->cert->raw_issuer_size = vlen;
 	return x509_fabricate_name(ctx, hdrlen, tag, &ctx->cert->issuer, vlen);
 }
 
@@ -330,6 +348,8 @@ int x509_note_subject(void *context, size_t hdrlen,
 		      const void *value, size_t vlen)
 {
 	struct x509_parse_context *ctx = context;
+	ctx->cert->raw_subject = value;
+	ctx->cert->raw_subject_size = vlen;
 	return x509_fabricate_name(ctx, hdrlen, tag, &ctx->cert->subject, vlen);
 }
 
diff --git a/crypto/asymmetric_keys/x509_parser.h b/crypto/asymmetric_keys/x509_parser.h
index 87d9cc26f63..1b76f207c1f 100644
--- a/crypto/asymmetric_keys/x509_parser.h
+++ b/crypto/asymmetric_keys/x509_parser.h
@@ -14,7 +14,9 @@
 
 struct x509_certificate {
 	struct x509_certificate *next;
+	struct x509_certificate *signer;	/* Certificate that signed this one */
 	struct public_key *pub;			/* Public key details */
+	struct public_key_signature sig;	/* Signature parameters */
 	char		*issuer;		/* Name of certificate issuer */
 	char		*subject;		/* Name of certificate subject */
 	char		*fingerprint;		/* Key fingerprint as hex */
@@ -25,7 +27,16 @@ struct x509_certificate {
 	unsigned	tbs_size;		/* Size of signed data */
 	unsigned	raw_sig_size;		/* Size of sigature */
 	const void	*raw_sig;		/* Signature data */
-	struct public_key_signature sig;	/* Signature parameters */
+	const void	*raw_serial;		/* Raw serial number in ASN.1 */
+	unsigned	raw_serial_size;
+	unsigned	raw_issuer_size;
+	const void	*raw_issuer;		/* Raw issuer name in ASN.1 */
+	const void	*raw_subject;		/* Raw subject name in ASN.1 */
+	unsigned	raw_subject_size;
+	unsigned	index;
+	bool		seen;			/* Infinite recursion prevention */
+	bool		verified;
+	bool		trusted;
 };
 
 /*