From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759287Ab2IMXus (ORCPT ); Thu, 13 Sep 2012 19:50:48 -0400 Received: from mx1.redhat.com ([209.132.183.28]:48206 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1759236Ab2IMXul (ORCPT ); Thu, 13 Sep 2012 19:50:41 -0400 From: David Howells Subject: [PATCH 16/16] X.509: Add a crypto key parser for binary (DER) X.509 certificates To: herbert@gondor.hengli.com.au, rusty@rustcorp.com.au Cc: linux-crypto@vger.kernel.org, zohar@us.ibm.com, dmitry.kasatkin@intel.com, linux-security-module@vger.kernel.org, linux-kernel@vger.kernel.org Date: Fri, 14 Sep 2012 00:50:23 +0100 Message-ID: <20120913235023.3575.67327.stgit@warthog.procyon.org.uk> In-Reply-To: <20120913234802.3575.77103.stgit@warthog.procyon.org.uk> References: <20120913234802.3575.77103.stgit@warthog.procyon.org.uk> User-Agent: StGIT/0.14.3 MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Add a crypto key parser for binary (DER) encoded X.509 certificates. The certificate is parsed and, if possible, the signature is verified. An X.509 key can be added like this: # keyctl padd crypto bar @s --- crypto/asymmetric_keys/.gitignore | 1 crypto/asymmetric_keys/Kconfig | 10 + crypto/asymmetric_keys/Makefile | 17 + crypto/asymmetric_keys/x509.asn1 | 60 +++ crypto/asymmetric_keys/x509_cert_parser.c | 503 +++++++++++++++++++++++++++++ crypto/asymmetric_keys/x509_parser.h | 37 ++ crypto/asymmetric_keys/x509_public_key.c | 206 ++++++++++++ crypto/asymmetric_keys/x509_rsakey.asn1 | 4 8 files changed, 838 insertions(+) create mode 100644 crypto/asymmetric_keys/.gitignore create mode 100644 crypto/asymmetric_keys/x509.asn1 create mode 100644 crypto/asymmetric_keys/x509_cert_parser.c create mode 100644 crypto/asymmetric_keys/x509_parser.h create mode 100644 crypto/asymmetric_keys/x509_public_key.c create mode 100644 crypto/asymmetric_keys/x509_rsakey.asn1 diff --git a/crypto/asymmetric_keys/.gitignore b/crypto/asymmetric_keys/.gitignore new file mode 100644 index 0000000..ee32837 --- /dev/null +++ b/crypto/asymmetric_keys/.gitignore @@ -0,0 +1 @@ +*-asn1.[ch] diff --git a/crypto/asymmetric_keys/Kconfig b/crypto/asymmetric_keys/Kconfig index 561759d..6d2c2ea 100644 --- a/crypto/asymmetric_keys/Kconfig +++ b/crypto/asymmetric_keys/Kconfig @@ -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 diff --git a/crypto/asymmetric_keys/Makefile b/crypto/asymmetric_keys/Makefile index 7c92691..0727204 100644 --- a/crypto/asymmetric_keys/Makefile +++ b/crypto/asymmetric_keys/Makefile @@ -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 diff --git a/crypto/asymmetric_keys/x509.asn1 b/crypto/asymmetric_keys/x509.asn1 new file mode 100644 index 0000000..a7ad4fc --- /dev/null +++ b/crypto/asymmetric_keys/x509.asn1 @@ -0,0 +1,60 @@ +Certificate ::= SEQUENCE { + tbsCertificate TBSCertificate ({ x509_note_tbs_certificate }), + signatureAlgorithm AlgorithmIdentifier, + signature BIT STRING ({ x509_note_signature }) + } ({ x509_note_cert_start }) + +TBSCertificate ::= SEQUENCE { + version [ 0 ] Version DEFAULT, + serialNumber CertificateSerialNumber ({ x509_note_serial }), + 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 }) + } diff --git a/crypto/asymmetric_keys/x509_cert_parser.c b/crypto/asymmetric_keys/x509_cert_parser.c new file mode 100644 index 0000000..cdcfce8 --- /dev/null +++ b/crypto/asymmetric_keys/x509_cert_parser.c @@ -0,0 +1,503 @@ +/* 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. + */ +#undef DEBUG +#define pr_fmt(fmt) "X.509: "fmt +#include +#include +#include +#include +#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 */ + int namesize; /* Usage of namebuffer */ + char namebuffer[256]; /* Name building buffer */ +}; + +/* + * Free an X.509 certificate + */ +void x509_free_certificate(struct x509_certificate *cert) +{ + if (cert) { + public_key_destroy(cert->pub); + kfree(cert->serial); + 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)); + printk("X.509: Unknown OID: [%zu] %s: %d\n", + (unsigned long)value - ctx->data, buffer, ctx->last_oid); + } + 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(,%02x,%ld,%zu)!\n", + tag, (unsigned long)value - ctx->data, vlen); + + ctx->cert->tbs = value; + ctx->cert->tbs_size = vlen; + return 0; +} + +/* + * Note the start position of the certificate content with respect to the TBS + * data and use this to compute the length of the TBS header which is needed + * for the signature check. + */ +int x509_note_cert_start(void *context, size_t hdrlen, + unsigned char tag, + const void *value, size_t vlen) +{ + struct x509_parse_context *ctx = context; + ptrdiff_t hdrsize; + + pr_debug("x509_note_cert_start(,%02x,%ld,%zu)!\n", + tag, (unsigned long)value - ctx->data, vlen); + + hdrsize = ctx->cert->tbs - value; + ctx->cert->tbs = value; + ctx->cert->tbs_size += hdrsize; + 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("X.509: 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; +} + +/* + * Extract name segments into the assembly buffer and tag them with prefixes + * appropriate to the attribute OID. + */ +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; + const char *prefix; + char pbuf[4]; + + switch (ctx->last_oid) { + case OID_commonName: prefix = "CN"; break; + case OID_surname: prefix = "S"; break; + case OID_countryName: prefix = "C"; break; + case OID_locality: prefix = "L"; break; + case OID_stateOrProvinceName: prefix = "ST"; break; + case OID_organizationName: prefix = "O"; break; + case OID_organizationUnitName: prefix = "OU"; break; + case OID_title: prefix = "T"; break; + case OID_name: prefix = "N"; break; + case OID_givenName: prefix = "G"; break; + case OID_initials: prefix = "I"; break; + case OID_generationalQualifier: prefix = "GQ"; break; + default: + sprintf(pbuf, "?%u", ctx->last_oid); + prefix = pbuf; + break; + } + + ctx->namesize += snprintf(ctx->namebuffer + ctx->namesize, + sizeof(ctx->namebuffer) - ctx->namesize, + "/%s=%*.*s", + prefix, + (int)vlen, (int)vlen, (const char *)value); + if (ctx->namesize > sizeof(ctx->namebuffer) - 1) + ctx->namesize = sizeof(ctx->namebuffer) - 1; + + return 0; +} + +/* + * Take a copy of the issuer name. + */ +int x509_note_issuer(void *context, size_t hdrlen, + unsigned char tag, + const void *value, size_t vlen) +{ + struct x509_parse_context *ctx = context; + + pr_debug("Issuer: %s\n", ctx->namebuffer); + + ctx->cert->issuer = kmalloc(ctx->namesize + 1, GFP_KERNEL); + if (!ctx->cert->issuer) + return -ENOMEM; + memcpy(ctx->cert->issuer, ctx->namebuffer, ctx->namesize); + ctx->cert->issuer[ctx->namesize] = 0; + ctx->namesize = 0; + return 0; +} + +/* + * Take a copy of the subject name. + */ +int x509_note_subject(void *context, size_t hdrlen, + unsigned char tag, + const void *value, size_t vlen) +{ + struct x509_parse_context *ctx = context; + pr_debug("Subject: %s\n", ctx->namebuffer); + + ctx->cert->subject = kmalloc(ctx->namesize + 1, GFP_KERNEL); + if (!ctx->cert->subject) + return -ENOMEM; + memcpy(ctx->cert->subject, ctx->namebuffer, ctx->namesize); + ctx->cert->subject[ctx->namesize] = 0; + ctx->namesize = 0; + 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; + + 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 keys 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; + + ctx->cert->pub->key_id_size = i = + min(vlen, sizeof(ctx->cert->pub->key_id)); + memcpy(ctx->cert->pub->key_id, v + vlen - i, i); + 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 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; + char *serial; + + for (; vlen > 0; vlen--, value++) + if (*(const u8 *)value != 0) + break; + + serial = kmalloc(vlen * 2 + 1, GFP_KERNEL); + if (!serial) + return -ENOMEM; + ctx->cert->serial = serial; + + /* Note: this limits the field width to a maximum of 64 */ + sprintf(serial, "%*phN", (int)vlen, value); + + pr_devel("Serial: %s\n", serial); + 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_warn("X.509: 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); +} diff --git a/crypto/asymmetric_keys/x509_parser.h b/crypto/asymmetric_keys/x509_parser.h new file mode 100644 index 0000000..b38789a --- /dev/null +++ b/crypto/asymmetric_keys/x509_parser.h @@ -0,0 +1,37 @@ +/* X.509 certificate 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 + +struct x509_certificate { + struct x509_certificate *next; + struct public_key *pub; /* Public key details */ + char *serial; /* Certificate serial number */ + char *issuer; /* Name of certificate issuer */ + char *subject; /* Name of certificate subject */ + char *fingerprint; /* Key fingerprint as hex */ + char *authority; /* Authority key fingerprint as hex */ + time_t valid_from; + time_t valid_to; + enum pkey_algo pkey_algo : 8; /* Public key algorithm */ + enum pkey_algo sig_pkey_algo : 8; /* Signature public key algorithm */ + enum pkey_hash_algo sig_hash_algo : 8; /* Signature hash algorithm */ + const void *tbs; /* Signed data */ + size_t tbs_size; /* Size of signed data */ + const void *sig; /* Signature data */ + size_t sig_size; /* Size of sigature */ +}; + +/* + * x509_cert_parser.c + */ +extern void x509_free_certificate(struct x509_certificate *cert); +extern struct x509_certificate *x509_cert_parse(const void *data, size_t datalen); diff --git a/crypto/asymmetric_keys/x509_public_key.c b/crypto/asymmetric_keys/x509_public_key.c new file mode 100644 index 0000000..a44c22c --- /dev/null +++ b/crypto/asymmetric_keys/x509_public_key.c @@ -0,0 +1,206 @@ +/* Instantiate a public key crypto key from an X.509 Certificate + * + * 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 +#include +#include +#include +#include +#include +#include +#include +#include +#include "asymmetric_keys.h" +#include "public_key.h" +#include "x509_parser.h" + +static const +struct public_key_algorithm *x509_public_key_algorithms[PKEY_ALGO__LAST] = { + [PKEY_ALGO_DSA] = NULL, +#if defined(CONFIG_PUBLIC_KEY_ALGO_RSA) || \ + defined(CONFIG_PUBLIC_KEY_ALGO_RSA_MODULE) + [PKEY_ALGO_RSA] = &RSA_public_key_algorithm, +#endif +}; + +/* + * Check the signature on a certificate using the provided public key + */ +static int x509_check_signature(const struct public_key *pub, + const struct x509_certificate *cert) +{ + struct public_key_signature *sig; + struct crypto_shash *tfm; + struct shash_desc *desc; + size_t digest_size, desc_size; + int ret; + + pr_devel("==>%s()\n", __func__); + + /* Allocate the hashing algorithm we're going to need and find out how + * big the hash operational data will be. + */ + tfm = crypto_alloc_shash(pkey_hash_algo[cert->sig_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); + digest_size = crypto_shash_digestsize(tfm); + + /* We allocate the hash operational data storage on the end of our + * context data. + */ + ret = -ENOMEM; + sig = kzalloc(sizeof(*sig) + desc_size + digest_size, GFP_KERNEL); + if (!sig) + goto error_no_sig; + + sig->pkey_hash_algo = cert->sig_hash_algo; + sig->digest = (u8 *)sig + sizeof(*sig) + desc_size; + sig->digest_size = digest_size; + + desc = (void *)sig + sizeof(*sig); + desc->tfm = tfm; + desc->flags = CRYPTO_TFM_REQ_MAY_SLEEP; + + ret = crypto_shash_init(desc); + if (ret < 0) + goto error; + + ret = -ENOMEM; + sig->rsa.s = mpi_read_raw_data(cert->sig, cert->sig_size); + if (!sig->rsa.s) + goto error; + + ret = crypto_shash_update(desc, cert->tbs, cert->tbs_size); + if (ret < 0) + goto error_mpi; + + sig->digest[0] = 0xa5; + sig->digest[1] = 0x5a; + + ret = crypto_shash_final(desc, sig->digest); + if (ret < 0) + goto error_mpi; + + ret = pub->algo->verify_signature(pub, sig); + + pr_debug("Cert Verification: %d\n", ret); + +error_mpi: + mpi_free(sig->rsa.s); +error: + kfree(sig); +error_no_sig: + crypto_free_shash(tfm); + + pr_devel("<==%s() = %d\n", __func__, ret); + return ret; +} + +/* + * Attempt to parse a data blob for a key as an X509 certificate. + */ +static int x509_key_preparse(struct key_preparsed_payload *prep) +{ + struct x509_certificate *cert; + time_t now; + size_t srlen, sulen; + char *desc = NULL; + int ret; + + cert = x509_cert_parse(prep->data, prep->datalen); + if (IS_ERR(cert)) + return PTR_ERR(cert); + + pr_devel("Cert Issuer: %s\n", cert->issuer); + pr_devel("Cert Subject: %s\n", cert->subject); + pr_devel("Cert Key Algo: %s\n", pkey_algo[cert->pkey_algo]); + pr_devel("Cert Valid: %lu - %lu\n", cert->valid_from, cert->valid_to); + pr_devel("Cert Signature: %s + %s\n", + pkey_algo[cert->sig_pkey_algo], + pkey_hash_algo[cert->sig_hash_algo]); + + now = CURRENT_TIME.tv_sec; + if (now < cert->valid_from) { + pr_warn("Cert %s is not yet valid\n", cert->fingerprint); + ret = -EKEYREJECTED; + goto error_free_cert; + } + if (now >= cert->valid_to) { + pr_warn("Cert %s has expired\n", cert->fingerprint); + ret = -EKEYEXPIRED; + goto error_free_cert; + } + + cert->pub->algo = x509_public_key_algorithms[cert->pkey_algo]; + cert->pub->id_type = PKEY_ID_X509; + + /* Check the signature on the key */ + if (strcmp(cert->fingerprint, cert->authority) == 0) { + ret = x509_check_signature(cert->pub, cert); + if (ret < 0) + goto error_free_cert; + } + + /* Propose a description */ + srlen = strlen(cert->serial); + sulen = strlen(cert->subject); + ret = -ENOMEM; + desc = kmalloc(srlen + sulen + 2, GFP_KERNEL); + if (!desc) + goto error_free_cert; + memcpy(desc, cert->serial, srlen); + desc[srlen] = ':'; + memcpy(desc + srlen + 1, cert->subject, sulen); + desc[srlen + sulen + 1] = 0; + + /* We're pinning the module by being linked against it */ + __module_get(public_key_subtype.owner); + prep->type_data[0] = &public_key_subtype; + prep->type_data[1] = cert->fingerprint; + prep->payload = cert->pub; + prep->description = desc; + prep->quotalen = 100; + + /* We've finished with the certificate */ + cert->pub = NULL; + cert->fingerprint = NULL; + desc = NULL; + ret = 0; + +error_free_cert: + x509_free_certificate(cert); + return ret; +} + +static struct asymmetric_key_parser x509_key_parser = { + .owner = THIS_MODULE, + .name = "x509", + .parse = x509_key_preparse, +}; + +/* + * Module stuff + */ +static int __init x509_key_init(void) +{ + return register_asymmetric_key_parser(&x509_key_parser); +} + +static void __exit x509_key_exit(void) +{ + unregister_asymmetric_key_parser(&x509_key_parser); +} + +module_init(x509_key_init); +module_exit(x509_key_exit); diff --git a/crypto/asymmetric_keys/x509_rsakey.asn1 b/crypto/asymmetric_keys/x509_rsakey.asn1 new file mode 100644 index 0000000..4ec7cc6 --- /dev/null +++ b/crypto/asymmetric_keys/x509_rsakey.asn1 @@ -0,0 +1,4 @@ +RSAPublicKey ::= SEQUENCE { + modulus INTEGER ({ rsa_extract_mpi }), -- n + publicExponent INTEGER ({ rsa_extract_mpi }) -- e + }