diff --git a/include/crypto/pkcs7.h b/include/crypto/pkcs7.h
new file mode 100644
index 000000000000..8f5c8a7ee3b9
--- /dev/null
+++ b/include/crypto/pkcs7.h
@@ -0,0 +1,47 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/* PKCS#7 crypto data parser
+ *
+ * Copyright (C) 2012 Red Hat, Inc. All Rights Reserved.
+ * Written by David Howells (dhowells@redhat.com)
+ */
+
+#ifndef _CRYPTO_PKCS7_H
+#define _CRYPTO_PKCS7_H
+
+#ifndef __UBOOT__
+#include <linux/verification.h>
+#include <crypto/public_key.h>
+#endif
+
+struct key;
+struct pkcs7_message;
+
+/*
+ * pkcs7_parser.c
+ */
+extern struct pkcs7_message *pkcs7_parse_message(const void *data,
+						 size_t datalen);
+extern void pkcs7_free_message(struct pkcs7_message *pkcs7);
+
+extern int pkcs7_get_content_data(const struct pkcs7_message *pkcs7,
+				  const void **_data, size_t *_datalen,
+				  size_t *_headerlen);
+
+#ifndef __UBOOT__
+/*
+ * pkcs7_trust.c
+ */
+extern int pkcs7_validate_trust(struct pkcs7_message *pkcs7,
+				struct key *trust_keyring);
+
+/*
+ * pkcs7_verify.c
+ */
+extern int pkcs7_verify(struct pkcs7_message *pkcs7,
+			enum key_being_used_for usage);
+
+extern int pkcs7_supply_detached_data(struct pkcs7_message *pkcs7,
+				      const void *data, size_t datalen);
+#endif
+
+#endif /* _CRYPTO_PKCS7_H */
diff --git a/lib/crypto/Kconfig b/lib/crypto/Kconfig
index aeb599c593ac..2b221b915aa6 100644
--- a/lib/crypto/Kconfig
+++ b/lib/crypto/Kconfig
@@ -39,4 +39,14 @@ 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
+	bool "PKCS#7 message parser"
+	depends on X509_CERTIFICATE_PARSER
+	select ASN1_DECODER
+	select ASN1_COMPILER
+	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.
+
 endif # ASYMMETRIC_KEY_TYPE
diff --git a/lib/crypto/Makefile b/lib/crypto/Makefile
index d7e27be568a1..8267fee0a7b8 100644
--- a/lib/crypto/Makefile
+++ b/lib/crypto/Makefile
@@ -36,3 +36,14 @@ $(obj)/x509_cert_parser.o: \
 
 $(obj)/x509.asn1.o: $(obj)/x509.asn1.c $(obj)/x509.asn1.h
 $(obj)/x509_akid.asn1.o: $(obj)/x509_akid.asn1.c $(obj)/x509_akid.asn1.h
+
+#
+# PKCS#7 message handling
+#
+obj-$(CONFIG_PKCS7_MESSAGE_PARSER) += pkcs7_message.o
+pkcs7_message-y := \
+	pkcs7.asn1.o \
+	pkcs7_parser.o
+
+$(obj)/pkcs7_parser.o: $(obj)/pkcs7.asn1.h
+$(obj)/pkcs7.asn1.o: $(obj)/pkcs7.asn1.c $(obj)/pkcs7.asn1.h
diff --git a/lib/crypto/pkcs7.asn1 b/lib/crypto/pkcs7.asn1
new file mode 100644
index 000000000000..1eca740b816a
--- /dev/null
+++ b/lib/crypto/pkcs7.asn1
@@ -0,0 +1,135 @@
+PKCS7ContentInfo ::= SEQUENCE {
+	contentType	ContentType ({ pkcs7_check_content_type }),
+	content		[0] EXPLICIT SignedData OPTIONAL
+}
+
+ContentType ::= OBJECT IDENTIFIER ({ pkcs7_note_OID })
+
+SignedData ::= SEQUENCE {
+	version			INTEGER ({ pkcs7_note_signeddata_version }),
+	digestAlgorithms	DigestAlgorithmIdentifiers,
+	contentInfo		ContentInfo ({ pkcs7_note_content }),
+	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 ({ pkcs7_note_OID }),
+	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 ({ pkcs7_note_signerinfo_version }),
+	sid			SignerIdentifier, -- CMS variant, not PKCS#7
+	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 })
+
+SignerIdentifier ::= CHOICE {
+	-- RFC5652 sec 5.3
+	issuerAndSerialNumber IssuerAndSerialNumber,
+        subjectKeyIdentifier [0] IMPLICIT SubjectKeyIdentifier
+}
+
+IssuerAndSerialNumber ::= SEQUENCE {
+	issuer			Name ({ pkcs7_sig_note_issuer }),
+	serialNumber		CertificateSerialNumber ({ pkcs7_sig_note_serial })
+}
+
+CertificateSerialNumber ::= INTEGER
+
+SubjectKeyIdentifier ::= OCTET STRING ({ pkcs7_sig_note_skid })
+
+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,
+	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/lib/crypto/pkcs7_parser.c b/lib/crypto/pkcs7_parser.c
new file mode 100644
index 000000000000..bf9e7e888f6b
--- /dev/null
+++ b/lib/crypto/pkcs7_parser.c
@@ -0,0 +1,693 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/* PKCS#7 parser
+ *
+ * Copyright (C) 2012 Red Hat, Inc. All Rights Reserved.
+ * Written by David Howells (dhowells@redhat.com)
+ */
+
+#define pr_fmt(fmt) "PKCS7: "fmt
+#ifdef __UBOOT__
+#include <linux/bitops.h>
+#include <linux/compat.h>
+#endif
+#include <linux/kernel.h>
+#ifndef __UBOOT__
+#include <linux/module.h>
+#include <linux/export.h>
+#include <linux/slab.h>
+#endif
+#include <linux/err.h>
+#include <linux/oid_registry.h>
+#include <crypto/public_key.h>
+#include "pkcs7_parser.h"
+#include "pkcs7.asn1.h"
+
+MODULE_DESCRIPTION("PKCS#7 parser");
+MODULE_AUTHOR("Red Hat, Inc.");
+MODULE_LICENSE("GPL");
+
+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;
+	const void	*raw_serial;
+	unsigned	raw_serial_size;
+	unsigned	raw_issuer_size;
+	const void	*raw_issuer;
+	const void	*raw_skid;
+	unsigned	raw_skid_size;
+	bool		expect_skid;
+};
+
+/*
+ * Free a signed information block.
+ */
+static void pkcs7_free_signed_info(struct pkcs7_signed_info *sinfo)
+{
+	if (sinfo) {
+		public_key_signature_free(sinfo->sig);
+		kfree(sinfo);
+	}
+}
+
+/**
+ * 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;
+			pkcs7_free_signed_info(sinfo);
+		}
+		kfree(pkcs7);
+	}
+}
+EXPORT_SYMBOL_GPL(pkcs7_free_message);
+
+/*
+ * Check authenticatedAttributes are provided or not provided consistently.
+ */
+static int pkcs7_check_authattrs(struct pkcs7_message *msg)
+{
+	struct pkcs7_signed_info *sinfo;
+	bool want = false;
+
+	sinfo = msg->signed_infos;
+	if (!sinfo)
+		goto inconsistent;
+
+	if (sinfo->authattrs) {
+		want = true;
+		msg->have_authattrs = true;
+	}
+
+	for (sinfo = sinfo->next; sinfo; sinfo = sinfo->next)
+		if (!!sinfo->authattrs != want)
+			goto inconsistent;
+	return 0;
+
+inconsistent:
+	pr_warn("Inconsistently supplied authAttrs\n");
+	return -EINVAL;
+}
+
+/**
+ * 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 = ERR_PTR(-ENOMEM);
+	int ret;
+
+	ctx = kzalloc(sizeof(struct pkcs7_parse_context), GFP_KERNEL);
+	if (!ctx)
+		goto out_no_ctx;
+	ctx->msg = kzalloc(sizeof(struct pkcs7_message), GFP_KERNEL);
+	if (!ctx->msg)
+		goto out_no_msg;
+	ctx->sinfo = kzalloc(sizeof(struct pkcs7_signed_info), GFP_KERNEL);
+	if (!ctx->sinfo)
+		goto out_no_sinfo;
+	ctx->sinfo->sig = kzalloc(sizeof(struct public_key_signature),
+				  GFP_KERNEL);
+	if (!ctx->sinfo->sig)
+		goto out_no_sig;
+
+	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) {
+		msg = ERR_PTR(ret);
+		goto out;
+	}
+
+	ret = pkcs7_check_authattrs(ctx->msg);
+	if (ret < 0) {
+		msg = ERR_PTR(ret);
+		goto out;
+	}
+
+	msg = ctx->msg;
+	ctx->msg = NULL;
+
+out:
+	while (ctx->certs) {
+		struct x509_certificate *cert = ctx->certs;
+		ctx->certs = cert->next;
+		x509_free_certificate(cert);
+	}
+out_no_sig:
+	pkcs7_free_signed_info(ctx->sinfo);
+out_no_sinfo:
+	pkcs7_free_message(ctx->msg);
+out_no_msg:
+	kfree(ctx);
+out_no_ctx:
+	return msg;
+}
+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
+ * @_headerlen: Size of ASN.1 header not included in _data
+ *
+ * Get access to the data content of the PKCS#7 message.  The size of the
+ * header of the ASN.1 object that contains it is also provided and can be used
+ * to adjust *_data and *_data_len to get the entire object.
+ *
+ * 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,
+			   size_t *_headerlen)
+{
+	if (!pkcs7->data)
+		return -ENODATA;
+
+	*_data = pkcs7->data;
+	*_data_len = pkcs7->data_len;
+	if (_headerlen)
+		*_headerlen = pkcs7->data_hdrlen;
+	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->hash_algo = "md4";
+		break;
+	case OID_md5:
+		ctx->sinfo->sig->hash_algo = "md5";
+		break;
+	case OID_sha1:
+		ctx->sinfo->sig->hash_algo = "sha1";
+		break;
+	case OID_sha256:
+		ctx->sinfo->sig->hash_algo = "sha256";
+		break;
+	case OID_sha384:
+		ctx->sinfo->sig->hash_algo = "sha384";
+		break;
+	case OID_sha512:
+		ctx->sinfo->sig->hash_algo = "sha512";
+		break;
+	case OID_sha224:
+		ctx->sinfo->sig->hash_algo = "sha224";
+		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 = "rsa";
+		ctx->sinfo->sig->encoding = "pkcs1";
+		break;
+	default:
+		printk("Unsupported pkey algo: %u\n", ctx->last_oid);
+		return -ENOPKG;
+	}
+	return 0;
+}
+
+/*
+ * We only support signed data [RFC2315 sec 9].
+ */
+int pkcs7_check_content_type(void *context, size_t hdrlen,
+			     unsigned char tag,
+			     const void *value, size_t vlen)
+{
+	struct pkcs7_parse_context *ctx = context;
+
+	if (ctx->last_oid != OID_signed_data) {
+		pr_warn("Only support pkcs7_signedData type\n");
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+/*
+ * Note the SignedData version
+ */
+int pkcs7_note_signeddata_version(void *context, size_t hdrlen,
+				  unsigned char tag,
+				  const void *value, size_t vlen)
+{
+	struct pkcs7_parse_context *ctx = context;
+	unsigned version;
+
+	if (vlen != 1)
+		goto unsupported;
+
+	ctx->msg->version = version = *(const u8 *)value;
+	switch (version) {
+	case 1:
+		/* PKCS#7 SignedData [RFC2315 sec 9.1]
+		 * CMS ver 1 SignedData [RFC5652 sec 5.1]
+		 */
+		break;
+	case 3:
+		/* CMS ver 3 SignedData [RFC2315 sec 5.1] */
+		break;
+	default:
+		goto unsupported;
+	}
+
+	return 0;
+
+unsupported:
+	pr_warn("Unsupported SignedData version\n");
+	return -EINVAL;
+}
+
+/*
+ * Note the SignerInfo version
+ */
+int pkcs7_note_signerinfo_version(void *context, size_t hdrlen,
+				  unsigned char tag,
+				  const void *value, size_t vlen)
+{
+	struct pkcs7_parse_context *ctx = context;
+	unsigned version;
+
+	if (vlen != 1)
+		goto unsupported;
+
+	version = *(const u8 *)value;
+	switch (version) {
+	case 1:
+		/* PKCS#7 SignerInfo [RFC2315 sec 9.2]
+		 * CMS ver 1 SignerInfo [RFC5652 sec 5.3]
+		 */
+		if (ctx->msg->version != 1)
+			goto version_mismatch;
+		ctx->expect_skid = false;
+		break;
+	case 3:
+		/* CMS ver 3 SignerInfo [RFC2315 sec 5.3] */
+		if (ctx->msg->version == 1)
+			goto version_mismatch;
+		ctx->expect_skid = true;
+		break;
+	default:
+		goto unsupported;
+	}
+
+	return 0;
+
+unsupported:
+	pr_warn("Unsupported SignerInfo version\n");
+	return -EINVAL;
+version_mismatch:
+	pr_warn("SignedData-SignerInfo version mismatch\n");
+	return -EBADMSG;
+}
+
+/*
+ * 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);
+
+	x509->index = ++ctx->x509_index;
+	pr_debug("Got cert %u for %s\n", x509->index, x509->subject);
+	pr_debug("- fingerprint %*phN\n", x509->id->len, x509->id->data);
+
+	*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;
+}
+
+/*
+ * Note the content type.
+ */
+int pkcs7_note_content(void *context, size_t hdrlen,
+		       unsigned char tag,
+		       const void *value, size_t vlen)
+{
+	struct pkcs7_parse_context *ctx = context;
+
+	if (ctx->last_oid != OID_data &&
+	    ctx->last_oid != OID_msIndirectData) {
+		pr_warn("Unsupported data type %d\n", ctx->last_oid);
+		return -EINVAL;
+	}
+
+	ctx->msg->data_type = ctx->last_oid;
+	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;
+	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;
+	struct pkcs7_signed_info *sinfo = ctx->sinfo;
+	enum OID content_type;
+
+	pr_devel("AuthAttr: %02x %zu [%*ph]\n", tag, vlen, (unsigned)vlen, value);
+
+	switch (ctx->last_oid) {
+	case OID_contentType:
+		if (__test_and_set_bit(sinfo_has_content_type, &sinfo->aa_set))
+			goto repeated;
+		content_type = look_up_OID(value, vlen);
+		if (content_type != ctx->msg->data_type) {
+			pr_warn("Mismatch between global data type (%d) and sinfo %u (%d)\n",
+				ctx->msg->data_type, sinfo->index,
+				content_type);
+			return -EBADMSG;
+		}
+		return 0;
+
+	case OID_signingTime:
+		if (__test_and_set_bit(sinfo_has_signing_time, &sinfo->aa_set))
+			goto repeated;
+		/* Should we check that the signing time is consistent
+		 * with the signer's X.509 cert?
+		 */
+		return x509_decode_time(&sinfo->signing_time,
+					hdrlen, tag, value, vlen);
+
+	case OID_messageDigest:
+		if (__test_and_set_bit(sinfo_has_message_digest, &sinfo->aa_set))
+			goto repeated;
+		if (tag != ASN1_OTS)
+			return -EBADMSG;
+		sinfo->msgdigest = value;
+		sinfo->msgdigest_len = vlen;
+		return 0;
+
+	case OID_smimeCapabilites:
+		if (__test_and_set_bit(sinfo_has_smime_caps, &sinfo->aa_set))
+			goto repeated;
+#ifdef __UBOOT__ /* OID_data is needed for authenticated UEFI variables */
+		if (ctx->msg->data_type != OID_msIndirectData &&
+		    ctx->msg->data_type != OID_data) {
+#else
+		if (ctx->msg->data_type != OID_msIndirectData) {
+#endif
+			pr_warn("S/MIME Caps only allowed with Authenticode\n");
+			return -EKEYREJECTED;
+		}
+		return 0;
+
+		/* Microsoft SpOpusInfo seems to be contain cont[0] 16-bit BE
+		 * char URLs and cont[1] 8-bit char URLs.
+		 *
+		 * Microsoft StatementType seems to contain a list of OIDs that
+		 * are also used as extendedKeyUsage types in X.509 certs.
+		 */
+	case OID_msSpOpusInfo:
+		if (__test_and_set_bit(sinfo_has_ms_opus_info, &sinfo->aa_set))
+			goto repeated;
+		goto authenticode_check;
+	case OID_msStatementType:
+		if (__test_and_set_bit(sinfo_has_ms_statement_type, &sinfo->aa_set))
+			goto repeated;
+	authenticode_check:
+		if (ctx->msg->data_type != OID_msIndirectData) {
+			pr_warn("Authenticode AuthAttrs only allowed with Authenticode\n");
+			return -EKEYREJECTED;
+		}
+		/* I'm not sure how to validate these */
+		return 0;
+	default:
+		return 0;
+	}
+
+repeated:
+	/* We permit max one item per AuthenticatedAttribute and no repeats */
+	pr_warn("Repeated/multivalue AuthAttrs not permitted\n");
+	return -EKEYREJECTED;
+}
+
+/*
+ * Note the set of auth attributes for digestion purposes [RFC2315 sec 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;
+	struct pkcs7_signed_info *sinfo = ctx->sinfo;
+
+	if (!test_bit(sinfo_has_content_type, &sinfo->aa_set) ||
+	    !test_bit(sinfo_has_message_digest, &sinfo->aa_set)) {
+		pr_warn("Missing required AuthAttr\n");
+		return -EBADMSG;
+	}
+
+	if (ctx->msg->data_type != OID_msIndirectData &&
+	    test_bit(sinfo_has_ms_opus_info, &sinfo->aa_set)) {
+		pr_warn("Unexpected Authenticode AuthAttr\n");
+		return -EBADMSG;
+	}
+
+	/* We need to switch the 'CONT 0' to a 'SET OF' when we digest */
+	sinfo->authattrs = value - (hdrlen - 1);
+	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->raw_serial = value;
+	ctx->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->raw_issuer = value;
+	ctx->raw_issuer_size = vlen;
+	return 0;
+}
+
+/*
+ * Note the issuing cert's subjectKeyIdentifier
+ */
+int pkcs7_sig_note_skid(void *context, size_t hdrlen,
+			unsigned char tag,
+			const void *value, size_t vlen)
+{
+	struct pkcs7_parse_context *ctx = context;
+
+	pr_devel("SKID: %02x %zu [%*ph]\n", tag, vlen, (unsigned)vlen, value);
+
+	ctx->raw_skid = value;
+	ctx->raw_skid_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;
+
+	ctx->sinfo->sig->s = kmemdup(value, vlen, GFP_KERNEL);
+	if (!ctx->sinfo->sig->s)
+		return -ENOMEM;
+
+	ctx->sinfo->sig->s_size = vlen;
+	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;
+	struct pkcs7_signed_info *sinfo = ctx->sinfo;
+	struct asymmetric_key_id *kid;
+
+	if (ctx->msg->data_type == OID_msIndirectData && !sinfo->authattrs) {
+		pr_warn("Authenticode requires AuthAttrs\n");
+		return -EBADMSG;
+	}
+
+	/* Generate cert issuer + serial number key ID */
+	if (!ctx->expect_skid) {
+		kid = asymmetric_key_generate_id(ctx->raw_serial,
+						 ctx->raw_serial_size,
+						 ctx->raw_issuer,
+						 ctx->raw_issuer_size);
+	} else {
+		kid = asymmetric_key_generate_id(ctx->raw_skid,
+						 ctx->raw_skid_size,
+						 "", 0);
+	}
+	if (IS_ERR(kid))
+		return PTR_ERR(kid);
+
+	pr_devel("SINFO KID: %u [%*phN]\n", kid->len, kid->len, kid->data);
+
+	sinfo->sig->auth_ids[0] = kid;
+	sinfo->index = ++ctx->sinfo_index;
+	*ctx->ppsinfo = sinfo;
+	ctx->ppsinfo = &sinfo->next;
+	ctx->sinfo = kzalloc(sizeof(struct pkcs7_signed_info), GFP_KERNEL);
+	if (!ctx->sinfo)
+		return -ENOMEM;
+	ctx->sinfo->sig = kzalloc(sizeof(struct public_key_signature),
+				  GFP_KERNEL);
+	if (!ctx->sinfo->sig)
+		return -ENOMEM;
+	return 0;
+}
diff --git a/lib/crypto/pkcs7_parser.h b/lib/crypto/pkcs7_parser.h
new file mode 100644
index 000000000000..6565fdc2d4ca
--- /dev/null
+++ b/lib/crypto/pkcs7_parser.h
@@ -0,0 +1,65 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/* PKCS#7 crypto data parser internal definitions
+ *
+ * Copyright (C) 2012 Red Hat, Inc. All Rights Reserved.
+ * Written by David Howells (dhowells@redhat.com)
+ */
+
+#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		unsupported_crypto;	/* T if not usable due to missing crypto */
+	bool		blacklisted;
+
+	/* 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;
+	unsigned long	aa_set;
+#define	sinfo_has_content_type		0
+#define	sinfo_has_signing_time		1
+#define	sinfo_has_message_digest	2
+#define sinfo_has_smime_caps		3
+#define	sinfo_has_ms_opus_info		4
+#define	sinfo_has_ms_statement_type	5
+	time64_t	signing_time;
+
+	/* 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.
+	 *
+	 * THis also contains the issuing cert serial number and issuer's name
+	 * [PKCS#7 or CMS ver 1] or issuing cert's SKID [CMS ver 3].
+	 */
+	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;
+	u8		version;	/* Version of cert (1 -> PKCS#7 or CMS; 3 -> CMS) */
+	bool		have_authattrs;	/* T if have authattrs */
+
+	/* 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/scripts/Makefile.build b/scripts/Makefile.build
index 6d59ea91fac3..26eb701f8dea 100644
--- a/scripts/Makefile.build
+++ b/scripts/Makefile.build
@@ -419,11 +419,9 @@ targets += $(multi-used-y) $(multi-used-m)
 intermediate_targets = $(foreach sfx, $(2), \
 				$(patsubst %$(strip $(1)),%$(sfx), \
 					$(filter %$(strip $(1)), $(targets))))
-# %.asn1.o <- %.asn1.[ch] <- %.asn1
 # %.lex.o <- %.lex.c <- %.l
 # %.tab.o <- %.tab.[ch] <- %.y
-targets += $(call intermediate_targets, .asn1.o, .asn1.c .asn1.h) \
-	   $(call intermediate_targets, .lex.o, .lex.c) \
+targets += $(call intermediate_targets, .lex.o, .lex.c) \
 	   $(call intermediate_targets, .tab.o, .tab.c .tab.h)
 
 # Descending
