1 files changed, 767 insertions, 0 deletions

diff --git a/crypto/asymmetric_keys/x509_cert_parser.c b/crypto/asymmetric_keys/x509_cert_parser.c
new file mode 100644
index 000000000..7a9b084e2
--- /dev/null
+++ b/crypto/asymmetric_keys/x509_cert_parser.c
@@ -0,0 +1,767 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/* X.509 certificate parser
+ *
+ * Copyright (C) 2012 Red Hat, Inc. All Rights Reserved.
+ * Written by David Howells (dhowells@redhat.com)
+ */
+
+#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>
+#include <crypto/public_key.h>
+#include "x509_parser.h"
+#include "x509.asn1.h"
+#include "x509_akid.asn1.h"
+
+struct x509_parse_context {
+	struct x509_certificate	*cert;		/* Certificate being constructed */
+	unsigned long	data;			/* Start of data */
+	const void	*key;			/* Key data */
+	size_t		key_size;		/* Size of key data */
+	const void	*params;		/* Key parameters */
+	size_t		params_size;		/* Size of key parameters */
+	enum OID	key_algo;		/* Algorithm used by the cert's key */
+	enum OID	last_oid;		/* Last OID encountered */
+	enum OID	sig_algo;		/* Algorithm used to sign the cert */
+	u8		o_size;			/* Size of organizationName (O) */
+	u8		cn_size;		/* Size of commonName (CN) */
+	u8		email_size;		/* Size of emailAddress */
+	u16		o_offset;		/* Offset of organizationName (O) */
+	u16		cn_offset;		/* Offset of commonName (CN) */
+	u16		email_offset;		/* Offset of emailAddress */
+	unsigned	raw_akid_size;
+	const void	*raw_akid;		/* Raw authorityKeyId in ASN.1 */
+	const void	*akid_raw_issuer;	/* Raw directoryName in authorityKeyId */
+	unsigned	akid_raw_issuer_size;
+};
+
+/*
+ * Free an X.509 certificate
+ */
+void x509_free_certificate(struct x509_certificate *cert)
+{
+	if (cert) {
+		public_key_free(cert->pub);
+		public_key_signature_free(cert->sig);
+		kfree(cert->issuer);
+		kfree(cert->subject);
+		kfree(cert->id);
+		kfree(cert->skid);
+		kfree(cert);
+	}
+}
+EXPORT_SYMBOL_GPL(x509_free_certificate);
+
+/*
+ * Parse an X.509 certificate
+ */
+struct x509_certificate *x509_cert_parse(const void *data, size_t datalen)
+{
+	struct x509_certificate *cert;
+	struct x509_parse_context *ctx;
+	struct asymmetric_key_id *kid;
+	long ret;
+
+	ret = -ENOMEM;
+	cert = kzalloc(sizeof(struct x509_certificate), GFP_KERNEL);
+	if (!cert)
+		goto error_no_cert;
+	cert->pub = kzalloc(sizeof(struct public_key), GFP_KERNEL);
+	if (!cert->pub)
+		goto error_no_ctx;
+	cert->sig = kzalloc(sizeof(struct public_key_signature), GFP_KERNEL);
+	if (!cert->sig)
+		goto error_no_ctx;
+	ctx = kzalloc(sizeof(struct x509_parse_context), GFP_KERNEL);
+	if (!ctx)
+		goto error_no_ctx;
+
+	ctx->cert = cert;
+	ctx->data = (unsigned long)data;
+
+	/* Attempt to decode the certificate */
+	ret = asn1_ber_decoder(&x509_decoder, ctx, data, datalen);
+	if (ret < 0)
+		goto error_decode;
+
+	/* Decode the AuthorityKeyIdentifier */
+	if (ctx->raw_akid) {
+		pr_devel("AKID: %u %*phN\n",
+			 ctx->raw_akid_size, ctx->raw_akid_size, ctx->raw_akid);
+		ret = asn1_ber_decoder(&x509_akid_decoder, ctx,
+				       ctx->raw_akid, ctx->raw_akid_size);
+		if (ret < 0) {
+			pr_warn("Couldn't decode AuthKeyIdentifier\n");
+			goto error_decode;
+		}
+	}
+
+	ret = -ENOMEM;
+	cert->pub->key = kmemdup(ctx->key, ctx->key_size, GFP_KERNEL);
+	if (!cert->pub->key)
+		goto error_decode;
+
+	cert->pub->keylen = ctx->key_size;
+
+	cert->pub->params = kmemdup(ctx->params, ctx->params_size, GFP_KERNEL);
+	if (!cert->pub->params)
+		goto error_decode;
+
+	cert->pub->paramlen = ctx->params_size;
+	cert->pub->algo = ctx->key_algo;
+
+	/* Grab the signature bits */
+	ret = x509_get_sig_params(cert);
+	if (ret < 0)
+		goto error_decode;
+
+	/* Generate cert issuer + serial number key ID */
+	kid = asymmetric_key_generate_id(cert->raw_serial,
+					 cert->raw_serial_size,
+					 cert->raw_issuer,
+					 cert->raw_issuer_size);
+	if (IS_ERR(kid)) {
+		ret = PTR_ERR(kid);
+		goto error_decode;
+	}
+	cert->id = kid;
+
+	/* Detect self-signed certificates */
+	ret = x509_check_for_self_signed(cert);
+	if (ret < 0)
+		goto error_decode;
+
+	kfree(ctx);
+	return cert;
+
+error_decode:
+	kfree(ctx);
+error_no_ctx:
+	x509_free_certificate(cert);
+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
+ * to interpret it.
+ */
+int x509_note_OID(void *context, size_t hdrlen,
+	     unsigned char tag,
+	     const void *value, size_t vlen)
+{
+	struct x509_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));
+		pr_debug("Unknown OID: [%lu] %s\n",
+			 (unsigned long)value - ctx->data, buffer);
+	}
+	return 0;
+}
+
+/*
+ * Save the position of the TBS data so that we can check the signature over it
+ * later.
+ */
+int x509_note_tbs_certificate(void *context, size_t hdrlen,
+			      unsigned char tag,
+			      const void *value, size_t vlen)
+{
+	struct x509_parse_context *ctx = context;
+
+	pr_debug("x509_note_tbs_certificate(,%zu,%02x,%ld,%zu)!\n",
+		 hdrlen, tag, (unsigned long)value - ctx->data, vlen);
+
+	ctx->cert->tbs = value - hdrlen;
+	ctx->cert->tbs_size = vlen + hdrlen;
+	return 0;
+}
+
+/*
+ * Record the algorithm that was used to sign this certificate.
+ */
+int x509_note_sig_algo(void *context, size_t hdrlen, unsigned char tag,
+		       const void *value, size_t vlen)
+{
+	struct x509_parse_context *ctx = context;
+
+	pr_debug("PubKey Algo: %u\n", ctx->last_oid);
+
+	switch (ctx->last_oid) {
+	case OID_md2WithRSAEncryption:
+	case OID_md3WithRSAEncryption:
+	default:
+		return -ENOPKG; /* Unsupported combination */
+
+	case OID_md4WithRSAEncryption:
+		ctx->cert->sig->hash_algo = "md4";
+		goto rsa_pkcs1;
+
+	case OID_sha1WithRSAEncryption:
+		ctx->cert->sig->hash_algo = "sha1";
+		goto rsa_pkcs1;
+
+	case OID_sha256WithRSAEncryption:
+		ctx->cert->sig->hash_algo = "sha256";
+		goto rsa_pkcs1;
+
+	case OID_sha384WithRSAEncryption:
+		ctx->cert->sig->hash_algo = "sha384";
+		goto rsa_pkcs1;
+
+	case OID_sha512WithRSAEncryption:
+		ctx->cert->sig->hash_algo = "sha512";
+		goto rsa_pkcs1;
+
+	case OID_sha224WithRSAEncryption:
+		ctx->cert->sig->hash_algo = "sha224";
+		goto rsa_pkcs1;
+
+	case OID_id_ecdsa_with_sha1:
+		ctx->cert->sig->hash_algo = "sha1";
+		goto ecdsa;
+
+	case OID_id_ecdsa_with_sha224:
+		ctx->cert->sig->hash_algo = "sha224";
+		goto ecdsa;
+
+	case OID_id_ecdsa_with_sha256:
+		ctx->cert->sig->hash_algo = "sha256";
+		goto ecdsa;
+
+	case OID_id_ecdsa_with_sha384:
+		ctx->cert->sig->hash_algo = "sha384";
+		goto ecdsa;
+
+	case OID_id_ecdsa_with_sha512:
+		ctx->cert->sig->hash_algo = "sha512";
+		goto ecdsa;
+
+	case OID_gost2012Signature256:
+		ctx->cert->sig->hash_algo = "streebog256";
+		goto ecrdsa;
+
+	case OID_gost2012Signature512:
+		ctx->cert->sig->hash_algo = "streebog512";
+		goto ecrdsa;
+
+	case OID_SM2_with_SM3:
+		ctx->cert->sig->hash_algo = "sm3";
+		goto sm2;
+	}
+
+rsa_pkcs1:
+	ctx->cert->sig->pkey_algo = "rsa";
+	ctx->cert->sig->encoding = "pkcs1";
+	ctx->sig_algo = ctx->last_oid;
+	return 0;
+ecrdsa:
+	ctx->cert->sig->pkey_algo = "ecrdsa";
+	ctx->cert->sig->encoding = "raw";
+	ctx->sig_algo = ctx->last_oid;
+	return 0;
+sm2:
+	ctx->cert->sig->pkey_algo = "sm2";
+	ctx->cert->sig->encoding = "raw";
+	ctx->sig_algo = ctx->last_oid;
+	return 0;
+ecdsa:
+	ctx->cert->sig->pkey_algo = "ecdsa";
+	ctx->cert->sig->encoding = "x962";
+	ctx->sig_algo = ctx->last_oid;
+	return 0;
+}
+
+/*
+ * Note the whereabouts and type of the signature.
+ */
+int x509_note_signature(void *context, size_t hdrlen,
+			unsigned char tag,
+			const void *value, size_t vlen)
+{
+	struct x509_parse_context *ctx = context;
+
+	pr_debug("Signature: alg=%u, size=%zu\n", ctx->last_oid, vlen);
+
+	/*
+	 * In X.509 certificates, the signature's algorithm is stored in two
+	 * places: inside the TBSCertificate (the data that is signed), and
+	 * alongside the signature.  These *must* match.
+	 */
+	if (ctx->last_oid != ctx->sig_algo) {
+		pr_warn("signatureAlgorithm (%u) differs from tbsCertificate.signature (%u)\n",
+			ctx->last_oid, ctx->sig_algo);
+		return -EINVAL;
+	}
+
+	if (strcmp(ctx->cert->sig->pkey_algo, "rsa") == 0 ||
+	    strcmp(ctx->cert->sig->pkey_algo, "ecrdsa") == 0 ||
+	    strcmp(ctx->cert->sig->pkey_algo, "sm2") == 0 ||
+	    strcmp(ctx->cert->sig->pkey_algo, "ecdsa") == 0) {
+		/* Discard the BIT STRING metadata */
+		if (vlen < 1 || *(const u8 *)value != 0)
+			return -EBADMSG;
+
+		value++;
+		vlen--;
+	}
+
+	ctx->cert->raw_sig = value;
+	ctx->cert->raw_sig_size = vlen;
+	return 0;
+}
+
+/*
+ * 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,
+			      unsigned char tag,
+			      const void *value, size_t vlen)
+{
+	struct x509_parse_context *ctx = context;
+
+	switch (ctx->last_oid) {
+	case OID_commonName:
+		ctx->cn_size = vlen;
+		ctx->cn_offset = (unsigned long)value - ctx->data;
+		break;
+	case OID_organizationName:
+		ctx->o_size = vlen;
+		ctx->o_offset = (unsigned long)value - ctx->data;
+		break;
+	case OID_email_address:
+		ctx->email_size = vlen;
+		ctx->email_offset = (unsigned long)value - ctx->data;
+		break;
+	default:
+		break;
+	}
+
+	return 0;
+}
+
+/*
+ * Fabricate and save the issuer and subject names
+ */
+static int x509_fabricate_name(struct x509_parse_context *ctx, size_t hdrlen,
+			       unsigned char tag,
+			       char **_name, size_t vlen)
+{
+	const void *name, *data = (const void *)ctx->data;
+	size_t namesize;
+	char *buffer;
+
+	if (*_name)
+		return -EINVAL;
+
+	/* Empty name string if no material */
+	if (!ctx->cn_size && !ctx->o_size && !ctx->email_size) {
+		buffer = kmalloc(1, GFP_KERNEL);
+		if (!buffer)
+			return -ENOMEM;
+		buffer[0] = 0;
+		goto done;
+	}
+
+	if (ctx->cn_size && ctx->o_size) {
+		/* Consider combining O and CN, but use only the CN if it is
+		 * prefixed by the O, or a significant portion thereof.
+		 */
+		namesize = ctx->cn_size;
+		name = data + ctx->cn_offset;
+		if (ctx->cn_size >= ctx->o_size &&
+		    memcmp(data + ctx->cn_offset, data + ctx->o_offset,
+			   ctx->o_size) == 0)
+			goto single_component;
+		if (ctx->cn_size >= 7 &&
+		    ctx->o_size >= 7 &&
+		    memcmp(data + ctx->cn_offset, data + ctx->o_offset, 7) == 0)
+			goto single_component;
+
+		buffer = kmalloc(ctx->o_size + 2 + ctx->cn_size + 1,
+				 GFP_KERNEL);
+		if (!buffer)
+			return -ENOMEM;
+
+		memcpy(buffer,
+		       data + ctx->o_offset, ctx->o_size);
+		buffer[ctx->o_size + 0] = ':';
+		buffer[ctx->o_size + 1] = ' ';
+		memcpy(buffer + ctx->o_size + 2,
+		       data + ctx->cn_offset, ctx->cn_size);
+		buffer[ctx->o_size + 2 + ctx->cn_size] = 0;
+		goto done;
+
+	} else if (ctx->cn_size) {
+		namesize = ctx->cn_size;
+		name = data + ctx->cn_offset;
+	} else if (ctx->o_size) {
+		namesize = ctx->o_size;
+		name = data + ctx->o_offset;
+	} else {
+		namesize = ctx->email_size;
+		name = data + ctx->email_offset;
+	}
+
+single_component:
+	buffer = kmalloc(namesize + 1, GFP_KERNEL);
+	if (!buffer)
+		return -ENOMEM;
+	memcpy(buffer, name, namesize);
+	buffer[namesize] = 0;
+
+done:
+	*_name = buffer;
+	ctx->cn_size = 0;
+	ctx->o_size = 0;
+	ctx->email_size = 0;
+	return 0;
+}
+
+int x509_note_issuer(void *context, size_t hdrlen,
+		     unsigned char tag,
+		     const void *value, size_t vlen)
+{
+	struct x509_parse_context *ctx = context;
+	struct asymmetric_key_id *kid;
+
+	ctx->cert->raw_issuer = value;
+	ctx->cert->raw_issuer_size = vlen;
+
+	if (!ctx->cert->sig->auth_ids[2]) {
+		kid = asymmetric_key_generate_id(value, vlen, "", 0);
+		if (IS_ERR(kid))
+			return PTR_ERR(kid);
+		ctx->cert->sig->auth_ids[2] = kid;
+	}
+
+	return x509_fabricate_name(ctx, hdrlen, tag, &ctx->cert->issuer, vlen);
+}
+
+int x509_note_subject(void *context, size_t hdrlen,
+		      unsigned char tag,
+		      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);
+}
+
+/*
+ * Extract the parameters for the public key
+ */
+int x509_note_params(void *context, size_t hdrlen,
+		     unsigned char tag,
+		     const void *value, size_t vlen)
+{
+	struct x509_parse_context *ctx = context;
+
+	/*
+	 * AlgorithmIdentifier is used three times in the x509, we should skip
+	 * first and ignore third, using second one which is after subject and
+	 * before subjectPublicKey.
+	 */
+	if (!ctx->cert->raw_subject || ctx->key)
+		return 0;
+	ctx->params = value - hdrlen;
+	ctx->params_size = vlen + hdrlen;
+	return 0;
+}
+
+/*
+ * Extract the data for the public key algorithm
+ */
+int x509_extract_key_data(void *context, size_t hdrlen,
+			  unsigned char tag,
+			  const void *value, size_t vlen)
+{
+	struct x509_parse_context *ctx = context;
+	enum OID oid;
+
+	ctx->key_algo = ctx->last_oid;
+	switch (ctx->last_oid) {
+	case OID_rsaEncryption:
+		ctx->cert->pub->pkey_algo = "rsa";
+		break;
+	case OID_gost2012PKey256:
+	case OID_gost2012PKey512:
+		ctx->cert->pub->pkey_algo = "ecrdsa";
+		break;
+	case OID_sm2:
+		ctx->cert->pub->pkey_algo = "sm2";
+		break;
+	case OID_id_ecPublicKey:
+		if (parse_OID(ctx->params, ctx->params_size, &oid) != 0)
+			return -EBADMSG;
+
+		switch (oid) {
+		case OID_sm2:
+			ctx->cert->pub->pkey_algo = "sm2";
+			break;
+		case OID_id_prime192v1:
+			ctx->cert->pub->pkey_algo = "ecdsa-nist-p192";
+			break;
+		case OID_id_prime256v1:
+			ctx->cert->pub->pkey_algo = "ecdsa-nist-p256";
+			break;
+		case OID_id_ansip384r1:
+			ctx->cert->pub->pkey_algo = "ecdsa-nist-p384";
+			break;
+		default:
+			return -ENOPKG;
+		}
+		break;
+	default:
+		return -ENOPKG;
+	}
+
+	/* Discard the BIT STRING metadata */
+	if (vlen < 1 || *(const u8 *)value != 0)
+		return -EBADMSG;
+	ctx->key = value + 1;
+	ctx->key_size = vlen - 1;
+	return 0;
+}
+
+/* The keyIdentifier in AuthorityKeyIdentifier SEQUENCE is tag(CONT,PRIM,0) */
+#define SEQ_TAG_KEYID (ASN1_CONT << 6)
+
+/*
+ * Process certificate extensions that are used to qualify the certificate.
+ */
+int x509_process_extension(void *context, size_t hdrlen,
+			   unsigned char tag,
+			   const void *value, size_t vlen)
+{
+	struct x509_parse_context *ctx = context;
+	struct asymmetric_key_id *kid;
+	const unsigned char *v = value;
+
+	pr_debug("Extension: %u\n", ctx->last_oid);
+
+	if (ctx->last_oid == OID_subjectKeyIdentifier) {
+		/* Get hold of the key fingerprint */
+		if (ctx->cert->skid || vlen < 3)
+			return -EBADMSG;
+		if (v[0] != ASN1_OTS || v[1] != vlen - 2)
+			return -EBADMSG;
+		v += 2;
+		vlen -= 2;
+
+		ctx->cert->raw_skid_size = vlen;
+		ctx->cert->raw_skid = v;
+		kid = asymmetric_key_generate_id(v, vlen, "", 0);
+		if (IS_ERR(kid))
+			return PTR_ERR(kid);
+		ctx->cert->skid = kid;
+		pr_debug("subjkeyid %*phN\n", kid->len, kid->data);
+		return 0;
+	}
+
+	if (ctx->last_oid == OID_authorityKeyIdentifier) {
+		/* Get hold of the CA key fingerprint */
+		ctx->raw_akid = v;
+		ctx->raw_akid_size = vlen;
+		return 0;
+	}
+
+	return 0;
+}
+
+/**
+ * x509_decode_time - Decode an X.509 time ASN.1 object
+ * @_t: The time to fill in
+ * @hdrlen: The length of the object header
+ * @tag: The object tag
+ * @value: The object value
+ * @vlen: The size of the object value
+ *
+ * Decode an ASN.1 universal time or generalised time field into a struct the
+ * kernel can handle and check it for validity.  The time is decoded thus:
+ *
+ *	[RFC5280 §4.1.2.5]
+ *	CAs conforming to this profile MUST always encode certificate validity
+ *	dates through the year 2049 as UTCTime; certificate validity dates in
+ *	2050 or later MUST be encoded as GeneralizedTime.  Conforming
+ *	applications MUST be able to process validity dates that are encoded in
+ *	either UTCTime or GeneralizedTime.
+ */
+int x509_decode_time(time64_t *_t,  size_t hdrlen,
+		     unsigned char tag,
+		     const unsigned char *value, size_t vlen)
+{
+	static const unsigned char month_lengths[] = { 31, 28, 31, 30, 31, 30,
+						       31, 31, 30, 31, 30, 31 };
+	const unsigned char *p = value;
+	unsigned year, mon, day, hour, min, sec, mon_len;
+
+#define dec2bin(X) ({ unsigned char x = (X) - '0'; if (x > 9) goto invalid_time; x; })
+#define DD2bin(P) ({ unsigned x = dec2bin(P[0]) * 10 + dec2bin(P[1]); P += 2; x; })
+
+	if (tag == ASN1_UNITIM) {
+		/* UTCTime: YYMMDDHHMMSSZ */
+		if (vlen != 13)
+			goto unsupported_time;
+		year = DD2bin(p);
+		if (year >= 50)
+			year += 1900;
+		else
+			year += 2000;
+	} else if (tag == ASN1_GENTIM) {
+		/* GenTime: YYYYMMDDHHMMSSZ */
+		if (vlen != 15)
+			goto unsupported_time;
+		year = DD2bin(p) * 100 + DD2bin(p);
+		if (year >= 1950 && year <= 2049)
+			goto invalid_time;
+	} else {
+		goto unsupported_time;
+	}
+
+	mon  = DD2bin(p);
+	day = DD2bin(p);
+	hour = DD2bin(p);
+	min  = DD2bin(p);
+	sec  = DD2bin(p);
+
+	if (*p != 'Z')
+		goto unsupported_time;
+
+	if (year < 1970 ||
+	    mon < 1 || mon > 12)
+		goto invalid_time;
+
+	mon_len = month_lengths[mon - 1];
+	if (mon == 2) {
+		if (year % 4 == 0) {
+			mon_len = 29;
+			if (year % 100 == 0) {
+				mon_len = 28;
+				if (year % 400 == 0)
+					mon_len = 29;
+			}
+		}
+	}
+
+	if (day < 1 || day > mon_len ||
+	    hour > 24 || /* ISO 8601 permits 24:00:00 as midnight tomorrow */
+	    min > 59 ||
+	    sec > 60) /* ISO 8601 permits leap seconds [X.680 46.3] */
+		goto invalid_time;
+
+	*_t = mktime64(year, mon, day, hour, min, sec);
+	return 0;
+
+unsupported_time:
+	pr_debug("Got unsupported time [tag %02x]: '%*phN'\n",
+		 tag, (int)vlen, value);
+	return -EBADMSG;
+invalid_time:
+	pr_debug("Got invalid time [tag %02x]: '%*phN'\n",
+		 tag, (int)vlen, value);
+	return -EBADMSG;
+}
+EXPORT_SYMBOL_GPL(x509_decode_time);
+
+int x509_note_not_before(void *context, size_t hdrlen,
+			 unsigned char tag,
+			 const void *value, size_t vlen)
+{
+	struct x509_parse_context *ctx = context;
+	return x509_decode_time(&ctx->cert->valid_from, hdrlen, tag, value, vlen);
+}
+
+int x509_note_not_after(void *context, size_t hdrlen,
+			unsigned char tag,
+			const void *value, size_t vlen)
+{
+	struct x509_parse_context *ctx = context;
+	return x509_decode_time(&ctx->cert->valid_to, hdrlen, tag, value, vlen);
+}
+
+/*
+ * Note a key identifier-based AuthorityKeyIdentifier
+ */
+int x509_akid_note_kid(void *context, size_t hdrlen,
+		       unsigned char tag,
+		       const void *value, size_t vlen)
+{
+	struct x509_parse_context *ctx = context;
+	struct asymmetric_key_id *kid;
+
+	pr_debug("AKID: keyid: %*phN\n", (int)vlen, value);
+
+	if (ctx->cert->sig->auth_ids[1])
+		return 0;
+
+	kid = asymmetric_key_generate_id(value, vlen, "", 0);
+	if (IS_ERR(kid))
+		return PTR_ERR(kid);
+	pr_debug("authkeyid %*phN\n", kid->len, kid->data);
+	ctx->cert->sig->auth_ids[1] = kid;
+	return 0;
+}
+
+/*
+ * Note a directoryName in an AuthorityKeyIdentifier
+ */
+int x509_akid_note_name(void *context, size_t hdrlen,
+			unsigned char tag,
+			const void *value, size_t vlen)
+{
+	struct x509_parse_context *ctx = context;
+
+	pr_debug("AKID: name: %*phN\n", (int)vlen, value);
+
+	ctx->akid_raw_issuer = value;
+	ctx->akid_raw_issuer_size = vlen;
+	return 0;
+}
+
+/*
+ * Note a serial number in an AuthorityKeyIdentifier
+ */
+int x509_akid_note_serial(void *context, size_t hdrlen,
+			  unsigned char tag,
+			  const void *value, size_t vlen)
+{
+	struct x509_parse_context *ctx = context;
+	struct asymmetric_key_id *kid;
+
+	pr_debug("AKID: serial: %*phN\n", (int)vlen, value);
+
+	if (!ctx->akid_raw_issuer || ctx->cert->sig->auth_ids[0])
+		return 0;
+
+	kid = asymmetric_key_generate_id(value,
+					 vlen,
+					 ctx->akid_raw_issuer,
+					 ctx->akid_raw_issuer_size);
+	if (IS_ERR(kid))
+		return PTR_ERR(kid);
+
+	pr_debug("authkeyid %*phN\n", kid->len, kid->data);
+	ctx->cert->sig->auth_ids[0] = kid;
+	return 0;
+}