/*
* Copyright (C) 2012 Michael Brown <mbrown@fensystems.co.uk>.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License as
* published by the Free Software Foundation; either version 2 of the
* License, or any later version.
*
* This program is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/
FILE_LICENCE ( GPL2_OR_LATER );
/** @file
*
* Cryptographic Message Syntax (PKCS #7)
*
* The format of CMS messages is defined in RFC 5652.
*
*/
#include <stdint.h>
#include <string.h>
#include <time.h>
#include <errno.h>
#include <ipxe/asn1.h>
#include <ipxe/x509.h>
#include <ipxe/uaccess.h>
#include <ipxe/cms.h>
/* Disambiguate the various error causes */
#define EACCES_NON_SIGNING \
__einfo_error ( EINFO_EACCES_NON_SIGNING )
#define EINFO_EACCES_NON_SIGNING \
__einfo_uniqify ( EINFO_EACCES, 0x01, "Not a signing certificate" )
#define EACCES_NON_CODE_SIGNING \
__einfo_error ( EINFO_EACCES_NON_CODE_SIGNING )
#define EINFO_EACCES_NON_CODE_SIGNING \
__einfo_uniqify ( EINFO_EACCES, 0x02, "Not a code-signing certificate" )
#define EACCES_INCOMPLETE \
__einfo_error ( EINFO_EACCES_INCOMPLETE )
#define EINFO_EACCES_INCOMPLETE \
__einfo_uniqify ( EINFO_EACCES, 0x03, "Incomplete certificate chain" )
#define EACCES_WRONG_NAME \
__einfo_error ( EINFO_EACCES_WRONG_NAME )
#define EINFO_EACCES_WRONG_NAME \
__einfo_uniqify ( EINFO_EACCES, 0x04, "Incorrect certificate name" )
#define EINVAL_DIGEST \
__einfo_error ( EINFO_EINVAL_DIGEST )
#define EINFO_EINVAL_DIGEST \
__einfo_uniqify ( EINFO_EINVAL, 0x01, "Not a digest algorithm" )
#define EINVAL_PUBKEY \
__einfo_error ( EINFO_EINVAL_PUBKEY )
#define EINFO_EINVAL_PUBKEY \
__einfo_uniqify ( EINFO_EINVAL, 0x02, "Not a public-key algorithm" )
#define ENOTSUP_SIGNEDDATA \
__einfo_error ( EINFO_ENOTSUP_SIGNEDDATA )
#define EINFO_ENOTSUP_SIGNEDDATA \
__einfo_uniqify ( EINFO_ENOTSUP, 0x01, "Not a digital signature" )
#define ENOTSUP_DIGEST \
__einfo_error ( EINFO_ENOTSUP_DIGEST )
#define EINFO_ENOTSUP_DIGEST \
__einfo_uniqify ( EINFO_ENOTSUP, 0x02, "Unsupported digest algorithm" )
#define ENOTSUP_PUBKEY \
__einfo_error ( EINFO_ENOTSUP_PUBKEY )
#define EINFO_ENOTSUP_PUBKEY \
__einfo_uniqify ( EINFO_ENOTSUP, 0x03, \
"Unsupported public-key algorithm" )
/** "pkcs7-signedData" object identifier */
static uint8_t oid_signeddata[] = { ASN1_OID_SIGNEDDATA };
/** "pkcs7-signedData" object identifier cursor */
static struct asn1_cursor oid_signeddata_cursor =
ASN1_OID_CURSOR ( oid_signeddata );
/**
* Parse CMS signature content type
*
* @v sig CMS signature
* @v raw ASN.1 cursor
* @ret rc Return status code
*/
static int cms_parse_content_type ( struct cms_signature *sig,
const struct asn1_cursor *raw ) {
struct asn1_cursor cursor;
/* Enter contentType */
memcpy ( &cursor, raw, sizeof ( cursor ) );
asn1_enter ( &cursor, ASN1_OID );
/* Check OID is pkcs7-signedData */
if ( asn1_compare ( &cursor, &oid_signeddata_cursor ) != 0 ) {
DBGC ( sig, "CMS %p does not contain signedData:\n", sig );
DBGC_HDA ( sig, 0, raw->data, raw->len );
return -ENOTSUP_SIGNEDDATA;
}
DBGC ( sig, "CMS %p contains signedData\n", sig );
return 0;
}
/**
* Parse CMS signature signer identifier
*
* @v sig CMS signature
* @v info Signer information to fill in
* @v raw ASN.1 cursor
* @ret rc Return status code
*/
static int cms_parse_signer_identifier ( struct cms_signature *sig,
struct cms_signer_info *info,
const struct asn1_cursor *raw ) {
struct asn1_cursor cursor;
int rc;
/* Enter issuerAndSerialNumber */
memcpy ( &cursor, raw, sizeof ( cursor ) );
asn1_enter ( &cursor, ASN1_SEQUENCE );
/* Record issuer */
memcpy ( &info->issuer, &cursor, sizeof ( info->issuer ) );
if ( ( rc = asn1_shrink ( &info->issuer, ASN1_SEQUENCE ) ) != 0 ) {
DBGC ( sig, "CMS %p/%p could not locate issuer: %s\n",
sig, info, strerror ( rc ) );
DBGC_HDA ( sig, 0, raw->data, raw->len );
return rc;
}
DBGC ( sig, "CMS %p/%p issuer is:\n", sig, info );
DBGC_HDA ( sig, 0, info->issuer.data, info->issuer.len );
asn1_skip_any ( &cursor );
/* Record serialNumber */
memcpy ( &info->serial, &cursor, sizeof ( info->serial ) );
if ( ( rc = asn1_shrink ( &info->serial, ASN1_INTEGER ) ) != 0 ) {
DBGC ( sig, "CMS %p/%p could not locate serialNumber: %s\n",
sig, info, strerror ( rc ) );
DBGC_HDA ( sig, 0, raw->data, raw->len );
return rc;
}
DBGC ( sig, "CMS %p/%p serial number is:\n", sig, info );
DBGC_HDA ( sig, 0, info->serial.data, info->serial.len );
return 0;
}
/**
* Parse CMS signature digest algorithm
*
* @v sig CMS signature
* @v info Signer information to fill in
* @v raw ASN.1 cursor
* @ret rc Return status code
*/
static int cms_parse_digest_algorithm ( struct cms_signature *sig,
struct cms_signer_info *info,
const struct asn1_cursor *raw ) {
struct asn1_algorithm *algorithm;
/* Identify algorithm */
algorithm = asn1_algorithm ( raw );
if ( ! algorithm ) {
DBGC ( sig, "CMS %p/%p could not identify digest algorithm:\n",
sig, info );
DBGC_HDA ( sig, 0, raw->data, raw->len );
return -ENOTSUP_DIGEST;
}
/* Check algorithm is a digest algorithm */
if ( ! algorithm->digest ) {
DBGC ( sig, "CMS %p/%p algorithm %s is not a digest "
"algorithm\n", sig, info, algorithm->name );
return -EINVAL_DIGEST;
}
/* Record digest algorithm */
info->digest = algorithm->digest;
DBGC ( sig, "CMS %p/%p digest algorithm is %s\n",
sig, info, algorithm->name );
return 0;
}
/**
* Parse CMS signature algorithm
*
* @v sig CMS signature
* @v info Signer information to fill in
* @v raw ASN.1 cursor
* @ret rc Return status code
*/
static int cms_parse_signature_algorithm ( struct cms_signature *sig,
struct cms_signer_info *info,
const struct asn1_cursor *raw ) {
struct asn1_algorithm *algorithm;
/* Identify algorithm */
algorithm = asn1_algorithm ( raw );
if ( ! algorithm ) {
DBGC ( sig, "CMS %p/%p could not identify public-key "
"algorithm:\n", sig, info );
DBGC_HDA ( sig, 0, raw->data, raw->len );
return -ENOTSUP_PUBKEY;
}
/* Check algorithm is a signature algorithm */
if ( ! algorithm->pubkey ) {
DBGC ( sig, "CMS %p/%p algorithm %s is not a public-key "
"algorithm\n", sig, info, algorithm->name );
return -EINVAL_PUBKEY;
}
/* Record signature algorithm */
info->pubkey = algorithm->pubkey;
DBGC ( sig, "CMS %p/%p public-key algorithm is %s\n",
sig, info, algorithm->name );
return 0;
}
/**
* Parse CMS signature value
*
* @v sig CMS signature
* @v info Signer information to fill in
* @v raw ASN.1 cursor
* @ret rc Return status code
*/
static int cms_parse_signature_value ( struct cms_signature *sig,
struct cms_signer_info *info,
const struct asn1_cursor *raw ) {
struct asn1_cursor cursor;
int rc;
/* Enter signature */
memcpy ( &cursor, raw, sizeof ( cursor ) );
if ( ( rc = asn1_enter ( &cursor, ASN1_OCTET_STRING ) ) != 0 ) {
DBGC ( sig, "CMS %p/%p could not locate signature:\n",
sig, info );
DBGC_HDA ( sig, 0, raw->data, raw->len );
return rc;
}
/* Record signature */
info->signature = cursor.data;
info->signature_len = cursor.len;
DBGC ( sig, "CMS %p/%p signature value is:\n", sig, info );
DBGC_HDA ( sig, 0, info->signature, info->signature_len );
return 0;
}
/**
* Parse CMS signature signer information
*
* @v sig CMS signature
* @v info Signer information to fill in
* @v raw ASN.1 cursor
* @ret rc Return status code
*/
static int cms_parse_signer_info ( struct cms_signature *sig,
struct cms_signer_info *info,
const struct asn1_cursor *raw ) {
struct asn1_cursor cursor;
int rc;
/* Enter signerInfo */
memcpy ( &cursor, raw, sizeof ( cursor ) );
asn1_enter ( &cursor, ASN1_SEQUENCE );
/* Skip version */
asn1_skip ( &cursor, ASN1_INTEGER );
/* Parse sid */
if ( ( rc = cms_parse_signer_identifier ( sig, info, &cursor ) ) != 0 )
return rc;
asn1_skip_any ( &cursor );
/* Parse digestAlgorithm */
if ( ( rc = cms_parse_digest_algorithm ( sig, info, &cursor ) ) != 0 )
return rc;
asn1_skip_any ( &cursor );
/* Skip signedAttrs, if present */
asn1_skip_if_exists ( &cursor, ASN1_EXPLICIT_TAG ( 0 ) );
/* Parse signatureAlgorithm */
if ( ( rc = cms_parse_signature_algorithm ( sig, info, &cursor ) ) != 0)
return rc;
asn1_skip_any ( &cursor );
/* Parse signature */
if ( ( rc = cms_parse_signature_value ( sig, info, &cursor ) ) != 0 )
return rc;
return 0;
}
/**
* Parse CMS signature from ASN.1 data
*
* @v sig CMS signature
* @v data Raw signature data
* @v len Length of raw data
* @ret rc Return status code
*/
int cms_parse ( struct cms_signature *sig, const void *data, size_t len ) {
struct asn1_cursor cursor;
int rc;
/* Initialise signature */
memset ( sig, 0, sizeof ( *sig ) );
cursor.data = data;
cursor.len = len;
/* Enter contentInfo */
asn1_enter ( &cursor, ASN1_SEQUENCE );
/* Parse contentType */
if ( ( rc = cms_parse_content_type ( sig, &cursor ) ) != 0 )
return rc;
asn1_skip_any ( &cursor );
/* Enter content */
asn1_enter ( &cursor, ASN1_EXPLICIT_TAG ( 0 ) );
/* Enter signedData */
asn1_enter ( &cursor, ASN1_SEQUENCE );
/* Skip version */
asn1_skip ( &cursor, ASN1_INTEGER );
/* Skip digestAlgorithms */
asn1_skip ( &cursor, ASN1_SET );
/* Skip encapContentInfo */
asn1_skip ( &cursor, ASN1_SEQUENCE );
/* Record certificates */
memcpy ( &sig->certificates, &cursor, sizeof ( sig->certificates ) );
if ( ( rc = asn1_enter ( &sig->certificates,
ASN1_EXPLICIT_TAG ( 0 ) ) ) != 0 ) {
DBGC ( sig, "CMS %p could not locate certificates:\n", sig );
DBGC_HDA ( sig, 0, data, len );
return rc;
}
asn1_skip_any ( &cursor );
/* Skip crls, if present */
asn1_skip_if_exists ( &cursor, ASN1_EXPLICIT_TAG ( 1 ) );
/* Enter signerInfos */
asn1_enter ( &cursor, ASN1_SET );
/* Parse first signerInfo */
if ( ( rc = cms_parse_signer_info ( sig, &sig->info, &cursor ) ) != 0 )
return rc;
return 0;
}
/** CMS certificate chain context */
struct cms_chain_context {
/** Signature */
struct cms_signature *sig;
/** Signer information */
struct cms_signer_info *info;
};
/**
* Parse next certificate in chain
*
* @v cert X.509 certificate to parse
* @v previous Previous X.509 certificate, or NULL
* @v ctx Chain context
* @ret rc Return status code
*/
static int cms_parse_next ( struct x509_certificate *cert,
const struct x509_certificate *previous,
void *ctx ) {
struct cms_chain_context *context = ctx;
struct cms_signature *sig = context->sig;
struct cms_signer_info *info = context->info;
struct asn1_cursor cursor;
int rc;
/* Search for relevant certificate */
memcpy ( &cursor, &sig->certificates, sizeof ( cursor ) );
while ( cursor.len ) {
/* Parse certificate */
if ( ( rc = x509_parse ( cert, cursor.data,
cursor.len ) ) != 0 ) {
DBGC ( sig, "CMS %p/%p could not parse certificate:\n",
sig, info );
DBGC_HDA ( sig, 0, cursor.data, cursor.len );
return rc;
}
if ( previous == NULL ) {
/* First certificate: check issuer and serial
* number against signer info
*/
if ( ( asn1_compare ( &info->issuer,
&cert->issuer.raw ) == 0 ) &&
( asn1_compare ( &info->serial,
&cert->serial.raw ) == 0 ) ) {
return 0;
}
} else {
/* Subsequent certificates: check subject
* against previous certificate's issuer.
*/
if ( asn1_compare ( &previous->issuer.raw,
&cert->subject.raw ) == 0 ) {
return 0;
}
}
/* Move to next certificate */
asn1_skip_any ( &cursor );
}
DBGC ( sig, "CMS %p/%p reached end of certificate chain\n", sig, info );
return -EACCES_INCOMPLETE;
}
/**
* Calculate digest of CMS-signed data
*
* @v sig CMS signature
* @v info Signer information
* @v data Signed data
* @v len Length of signed data
* @v out Digest output
*/
static void cms_digest ( struct cms_signature *sig,
struct cms_signer_info *info,
userptr_t data, size_t len, void *out ) {
struct digest_algorithm *digest = info->digest;
uint8_t ctx[ digest->ctxsize ];
uint8_t block[ digest->blocksize ];
size_t offset = 0;
size_t frag_len;
/* Initialise digest */
digest_init ( digest, ctx );
/* Process data one block at a time */
while ( len ) {
frag_len = len;
if ( frag_len > sizeof ( block ) )
frag_len = sizeof ( block );
copy_from_user ( block, data, offset, frag_len );
digest_update ( digest, ctx, block, frag_len );
offset += frag_len;
len -= frag_len;
}
/* Finalise digest */
digest_final ( digest, ctx, out );
DBGC ( sig, "CMS %p/%p digest value:\n", sig, info );
DBGC_HDA ( sig, 0, out, digest->digestsize );
}
/**
* Verify digest of CMS-signed data
*
* @v sig CMS signature
* @v info Signer information
* @v cert Corresponding certificate
* @v data Signed data
* @v len Length of signed data
* @ret rc Return status code
*/
static int cms_verify_digest ( struct cms_signature *sig,
struct cms_signer_info *info,
struct x509_certificate *cert,
userptr_t data, size_t len ) {
struct digest_algorithm *digest = info->digest;
struct pubkey_algorithm *pubkey = info->pubkey;
struct x509_public_key *public_key = &cert->subject.public_key;
uint8_t digest_out[ digest->digestsize ];
uint8_t ctx[ pubkey->ctxsize ];
int rc;
/* Generate digest */
cms_digest ( sig, info, data, len, digest_out );
/* Initialise public-key algorithm */
if ( ( rc = pubkey_init ( pubkey, ctx, public_key->raw.data,
public_key->raw.len ) ) != 0 ) {
DBGC ( sig, "CMS %p/%p could not initialise public key: %s\n",
sig, info, strerror ( rc ) );
goto err_init;
}
/* Verify digest */
if ( ( rc = pubkey_verify ( pubkey, ctx, digest, digest_out,
info->signature,
info->signature_len ) ) != 0 ) {
DBGC ( sig, "CMS %p/%p signature verification failed: %s\n",
sig, info, strerror ( rc ) );
goto err_verify;
}
err_verify:
pubkey_final ( pubkey, ctx );
err_init:
return rc;
}
/**
* Verify CMS signature signer information
*
* @v sig CMS signature
* @v info Signer information
* @v data Signed data
* @v len Length of signed data
* @v name Required common name, or NULL to allow any name
* @v time Time at which to validate certificates
* @v root Root certificate store, or NULL to use default
* @ret rc Return status code
*/
static int cms_verify_signer_info ( struct cms_signature *sig,
struct cms_signer_info *info,
userptr_t data, size_t len,
const char *name, time_t time,
struct x509_root *root ) {
struct cms_chain_context context;
struct x509_certificate cert;
int rc;
/* Validate certificate chain */
context.sig = sig;
context.info = info;
if ( ( rc = x509_validate_chain ( cms_parse_next, &context, time, root,
&cert ) ) != 0 ) {
DBGC ( sig, "CMS %p/%p could not validate chain: %s\n",
sig, info, strerror ( rc ) );
return rc;
}
/* Check that certificate can create digital signatures */
if ( ! ( cert.extensions.usage.bits & X509_DIGITAL_SIGNATURE ) ) {
DBGC ( sig, "CMS %p/%p certificate cannot create signatures\n",
sig, info );
return -EACCES_NON_SIGNING;
}
/* Check that certificate can sign code */
if ( ! ( cert.extensions.ext_usage.bits & X509_CODE_SIGNING ) ) {
DBGC ( sig, "CMS %p/%p certificate is not code-signing\n",
sig, info );
return -EACCES_NON_CODE_SIGNING;
}
/* Check certificate name, if applicable */
if ( ( name != NULL ) &&
( ( cert.subject.name.len != strlen ( name ) ) ||
( memcmp ( cert.subject.name.data, name,
cert.subject.name.len ) != 0 ) ) ) {
DBGC ( sig, "CMS %p/%p certificate name incorrect\n",
sig, info );
return -EACCES_WRONG_NAME;
}
/* Verify digest */
if ( ( rc = cms_verify_digest ( sig, info, &cert, data, len ) ) != 0 )
return rc;
return 0;
}
/**
* Verify CMS signature
*
* @v sig CMS signature
* @v data Signed data
* @v len Length of signed data
* @v name Required common name, or NULL to allow any name
* @v time Time at which to validate certificates
* @v root Root certificate store, or NULL to use default
* @ret rc Return status code
*/
int cms_verify ( struct cms_signature *sig, userptr_t data, size_t len,
const char *name, time_t time, struct x509_root *root ) {
int rc;
/* Verify using first signerInfo */
if ( ( rc = cms_verify_signer_info ( sig, &sig->info, data, len,
name, time, root ) ) != 0 )
return rc;
return 0;
}
