X.509: Add a crypto key parser for binary (DER) X.509 certificates (c26fd69f) · Commits · 戴 / test

crypto/asymmetric_keys/.gitignore

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		*-asn1.[ch]

crypto/asymmetric_keys/Kconfig

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		@@ -25,4 +25,14 @@ config PUBLIC_KEY_ALGO_RSA
		help
		This option enables support for the RSA algorithm (PKCS#1, RFC3447).

		config X509_CERTIFICATE_PARSER
		tristate "X.509 certificate parser"
		depends on ASYMMETRIC_PUBLIC_KEY_SUBTYPE
		select ASN1
		select OID_REGISTRY
		help
		This option procides support for parsing X.509 format blobs for key
		data and provides the ability to instantiate a crypto key from a
		public key packet found inside the certificate.

		endif # ASYMMETRIC_KEY_TYPE

crypto/asymmetric_keys/Makefile

+17 −0

Original line number	Diff line number	Diff line
		@@ -8,3 +8,20 @@ asymmetric_keys-y := asymmetric_type.o signature.o

		obj-$(CONFIG_ASYMMETRIC_PUBLIC_KEY_SUBTYPE) += public_key.o
		obj-$(CONFIG_PUBLIC_KEY_ALGO_RSA) += rsa.o

		#
		# X.509 Certificate handling
		#
		obj-$(CONFIG_X509_CERTIFICATE_PARSER) += x509_key_parser.o
		x509_key_parser-y := \
		x509-asn1.o \
		x509_rsakey-asn1.o \
		x509_cert_parser.o \
		x509_public_key.o

		$(obj)/x509_cert_parser.o: $(obj)/x509-asn1.h $(obj)/x509_rsakey-asn1.h
		$(obj)/x509-asn1.o: $(obj)/x509-asn1.c $(obj)/x509-asn1.h
		$(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

crypto/asymmetric_keys/x509.asn1

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		Certificate ::= SEQUENCE {
		tbsCertificate TBSCertificate ({ x509_note_tbs_certificate }),
		signatureAlgorithm AlgorithmIdentifier,
		signature BIT STRING ({ x509_note_signature })
		}

		TBSCertificate ::= SEQUENCE {
		version [ 0 ] Version DEFAULT,
		serialNumber CertificateSerialNumber,
		signature AlgorithmIdentifier ({ x509_note_pkey_algo }),
		issuer Name ({ x509_note_issuer }),
		validity Validity,
		subject Name ({ x509_note_subject }),
		subjectPublicKeyInfo SubjectPublicKeyInfo,
		issuerUniqueID [ 1 ] IMPLICIT UniqueIdentifier OPTIONAL,
		subjectUniqueID [ 2 ] IMPLICIT UniqueIdentifier OPTIONAL,
		extensions [ 3 ] Extensions OPTIONAL
		}

		Version ::= INTEGER
		CertificateSerialNumber ::= INTEGER

		AlgorithmIdentifier ::= SEQUENCE {
		algorithm OBJECT IDENTIFIER ({ x509_note_OID }),
		parameters ANY OPTIONAL
		}

		Name ::= SEQUENCE OF RelativeDistinguishedName

		RelativeDistinguishedName ::= SET OF AttributeValueAssertion

		AttributeValueAssertion ::= SEQUENCE {
		attributeType OBJECT IDENTIFIER ({ x509_note_OID }),
		attributeValue ANY ({ x509_extract_name_segment })
		}

		Validity ::= SEQUENCE {
		notBefore Time ({ x509_note_not_before }),
		notAfter Time ({ x509_note_not_after })
		}

		Time ::= CHOICE {
		utcTime UTCTime,
		generalTime GeneralizedTime
		}

		SubjectPublicKeyInfo ::= SEQUENCE {
		algorithm AlgorithmIdentifier,
		subjectPublicKey BIT STRING ({ x509_extract_key_data })
		}

		UniqueIdentifier ::= BIT STRING

		Extensions ::= SEQUENCE OF Extension

		Extension ::= SEQUENCE {
		extnid OBJECT IDENTIFIER ({ x509_note_OID }),
		critical BOOLEAN DEFAULT,
		extnValue OCTET STRING ({ x509_process_extension })
		}

crypto/asymmetric_keys/x509_cert_parser.c

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		/* X.509 certificate 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) "X.509: "fmt
		#include <linux/kernel.h>
		#include <linux/slab.h>
		#include <linux/err.h>
		#include <linux/oid_registry.h>
		#include "public_key.h"
		#include "x509_parser.h"
		#include "x509-asn1.h"
		#include "x509_rsakey-asn1.h"

		struct x509_parse_context {
		struct x509_certificate cert; / Certificate being constructed */
		unsigned long data; /* Start of data */
		const void cert_start; / Start of cert content */
		const void key; / Key data */
		size_t key_size; /* Size of key data */
		enum OID last_oid; /* Last OID encountered */
		enum OID algo_oid; /* Algorithm OID */
		unsigned char nr_mpi; /* Number of MPIs stored */
		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 */
		};

		/*
		* Free an X.509 certificate
		*/
		void x509_free_certificate(struct x509_certificate *cert)
		{
		if (cert) {
		public_key_destroy(cert->pub);
		kfree(cert->issuer);
		kfree(cert->subject);
		kfree(cert->fingerprint);
		kfree(cert->authority);
		kfree(cert);
		}
		}

		/*
		* 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;
		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;
		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 public key */
		ret = asn1_ber_decoder(&x509_rsakey_decoder, ctx,
		ctx->key, ctx->key_size);
		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);
		}

		/*
		* 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: [%zu] %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 public key algorithm
		*/
		int x509_note_pkey_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 = PKEY_HASH_MD5;
		ctx->cert->sig_pkey_algo = PKEY_ALGO_RSA;
		break;

		case OID_sha1WithRSAEncryption:
		ctx->cert->sig_hash_algo = PKEY_HASH_SHA1;
		ctx->cert->sig_pkey_algo = PKEY_ALGO_RSA;
		break;

		case OID_sha256WithRSAEncryption:
		ctx->cert->sig_hash_algo = PKEY_HASH_SHA256;
		ctx->cert->sig_pkey_algo = PKEY_ALGO_RSA;
		break;

		case OID_sha384WithRSAEncryption:
		ctx->cert->sig_hash_algo = PKEY_HASH_SHA384;
		ctx->cert->sig_pkey_algo = PKEY_ALGO_RSA;
		break;

		case OID_sha512WithRSAEncryption:
		ctx->cert->sig_hash_algo = PKEY_HASH_SHA512;
		ctx->cert->sig_pkey_algo = PKEY_ALGO_RSA;
		break;

		case OID_sha224WithRSAEncryption:
		ctx->cert->sig_hash_algo = PKEY_HASH_SHA224;
		ctx->cert->sig_pkey_algo = PKEY_ALGO_RSA;
		break;
		}

		ctx->algo_oid = 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 type: %u size %zu\n", ctx->last_oid, vlen);

		if (ctx->last_oid != ctx->algo_oid) {
		pr_warn("Got cert with pkey (%u) and sig (%u) algorithm OIDs\n",
		ctx->algo_oid, ctx->last_oid);
		return -EINVAL;
		}

		ctx->cert->sig = value;
		ctx->cert->sig_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;
		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;
		return x509_fabricate_name(ctx, hdrlen, tag, &ctx->cert->subject, vlen);
		}

		/*
		* 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;

		if (ctx->last_oid != OID_rsaEncryption)
		return -ENOPKG;

		/* There seems to be an extraneous 0 byte on the front of the data */
		ctx->cert->pkey_algo = PKEY_ALGO_RSA;
		ctx->key = value + 1;
		ctx->key_size = vlen - 1;
		return 0;
		}

		/*
		* Extract a RSA public key value
		*/
		int rsa_extract_mpi(void *context, size_t hdrlen,
		unsigned char tag,
		const void *value, size_t vlen)
		{
		struct x509_parse_context *ctx = context;
		MPI mpi;

		if (ctx->nr_mpi >= ARRAY_SIZE(ctx->cert->pub->mpi)) {
		pr_err("Too many public key MPIs in certificate\n");
		return -EBADMSG;
		}

		mpi = mpi_read_raw_data(value, vlen);
		if (!mpi)
		return -ENOMEM;

		ctx->cert->pub->mpi[ctx->nr_mpi++] = mpi;
		return 0;
		}

		/*
		* 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;
		const unsigned char *v = value;
		char *f;
		int i;

		pr_debug("Extension: %u\n", ctx->last_oid);

		if (ctx->last_oid == OID_subjectKeyIdentifier) {
		/* Get hold of the key fingerprint */
		if (vlen < 3)
		return -EBADMSG;
		if (v[0] != ASN1_OTS \|\| v[1] != vlen - 2)
		return -EBADMSG;
		v += 2;
		vlen -= 2;

		f = kmalloc(vlen * 2 + 1, GFP_KERNEL);
		if (!f)
		return -ENOMEM;
		for (i = 0; i < vlen; i++)
		sprintf(f + i * 2, "%02x", v[i]);
		pr_debug("fingerprint %s\n", f);
		ctx->cert->fingerprint = f;
		return 0;
		}

		if (ctx->last_oid == OID_authorityKeyIdentifier) {
		/* Get hold of the CA key fingerprint */
		if (vlen < 5)
		return -EBADMSG;
		if (v[0] != (ASN1_SEQ \| (ASN1_CONS << 5)) \|\|
		v[1] != vlen - 2 \|\|
		v[2] != (ASN1_CONT << 6) \|\|
		v[3] != vlen - 4)
		return -EBADMSG;
		v += 4;
		vlen -= 4;

		f = kmalloc(vlen * 2 + 1, GFP_KERNEL);
		if (!f)
		return -ENOMEM;
		for (i = 0; i < vlen; i++)
		sprintf(f + i * 2, "%02x", v[i]);
		pr_debug("authority %s\n", f);
		ctx->cert->authority = f;
		return 0;
		}

		return 0;
		}

		/*
		* Record a certificate time.
		*/
		static int x509_note_time(time_t *_time, size_t hdrlen,
		unsigned char tag,
		const unsigned char *value, size_t vlen)
		{
		unsigned YY, MM, DD, hh, mm, ss;
		const unsigned char *p = value;

		#define dec2bin(X) ((X) - '0')
		#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;
		YY = DD2bin(p);
		if (YY > 50)
		YY += 1900;
		else
		YY += 2000;
		} else if (tag == ASN1_GENTIM) {
		/* GenTime: YYYYMMDDHHMMSSZ */
		if (vlen != 15)
		goto unsupported_time;
		YY = DD2bin(p) * 100 + DD2bin(p);
		} else {
		goto unsupported_time;
		}

		MM = DD2bin(p);
		DD = DD2bin(p);
		hh = DD2bin(p);
		mm = DD2bin(p);
		ss = DD2bin(p);

		if (*p != 'Z')
		goto unsupported_time;

		*_time = mktime(YY, MM, DD, hh, mm, ss);
		return 0;

		unsupported_time:
		pr_debug("Got unsupported time [tag %02x]: '%.s'\n",
		tag, (int)vlen, (int)vlen, value);
		return -EBADMSG;
		}

		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_note_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_note_time(&ctx->cert->valid_to, hdrlen, tag, value, vlen);
		}

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