Commit 2e3fadbf authored by David Howells's avatar David Howells

PKCS#7: Implement a parser [RFC 2315]

Implement a parser for a PKCS#7 signed-data message as described in part of
RFC 2315.
Signed-off-by: default avatarDavid Howells <dhowells@redhat.com>
Acked-by: default avatarVivek Goyal <vgoyal@redhat.com>
Reviewed-by: default avatarKees Cook <keescook@chromium.org>
parent ace0107a
......@@ -37,4 +37,13 @@ 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
tristate "PKCS#7 message parser"
depends on X509_CERTIFICATE_PARSER
select ASN1
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
......@@ -25,3 +25,16 @@ $(obj)/x509_rsakey-asn1.o: $(obj)/x509_rsakey-asn1.c $(obj)/x509_rsakey-asn1.h
clean-files += x509-asn1.c x509-asn1.h
clean-files += x509_rsakey-asn1.c x509_rsakey-asn1.h
#
# PKCS#7 message handling
#
obj-$(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
clean-files += pkcs7-asn1.c pkcs7-asn1.h
PKCS7ContentInfo ::= SEQUENCE {
contentType ContentType,
content [0] EXPLICIT SignedData OPTIONAL
}
ContentType ::= OBJECT IDENTIFIER ({ pkcs7_note_OID })
SignedData ::= SEQUENCE {
version INTEGER,
digestAlgorithms DigestAlgorithmIdentifiers,
contentInfo ContentInfo,
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,
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,
issuerAndSerialNumber IssuerAndSerialNumber,
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 })
IssuerAndSerialNumber ::= SEQUENCE {
issuer Name ({ pkcs7_sig_note_issuer }),
serialNumber CertificateSerialNumber ({ pkcs7_sig_note_serial })
}
CertificateSerialNumber ::= INTEGER
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 ({ pkcs7_note_OID }),
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
}
/* PKCS#7 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) "PKCS7: "fmt
#include <linux/kernel.h>
#include <linux/export.h>
#include <linux/slab.h>
#include <linux/err.h>
#include <linux/oid_registry.h>
#include "public_key.h"
#include "pkcs7_parser.h"
#include "pkcs7-asn1.h"
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;
};
/**
* 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;
mpi_free(sinfo->sig.mpi[0]);
kfree(sinfo->sig.digest);
kfree(sinfo);
}
kfree(pkcs7);
}
}
EXPORT_SYMBOL_GPL(pkcs7_free_message);
/**
* 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;
long ret;
ret = -ENOMEM;
msg = kzalloc(sizeof(struct pkcs7_message), GFP_KERNEL);
if (!msg)
goto error_no_sig;
ctx = kzalloc(sizeof(struct pkcs7_parse_context), GFP_KERNEL);
if (!ctx)
goto error_no_ctx;
ctx->sinfo = kzalloc(sizeof(struct pkcs7_signed_info), GFP_KERNEL);
if (!ctx->sinfo)
goto error_no_sinfo;
ctx->msg = msg;
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)
goto error_decode;
while (ctx->certs) {
struct x509_certificate *cert = ctx->certs;
ctx->certs = cert->next;
x509_free_certificate(cert);
}
mpi_free(ctx->sinfo->sig.mpi[0]);
kfree(ctx->sinfo->sig.digest);
kfree(ctx->sinfo);
kfree(ctx);
return msg;
error_decode:
mpi_free(ctx->sinfo->sig.mpi[0]);
kfree(ctx->sinfo->sig.digest);
kfree(ctx->sinfo);
error_no_sinfo:
kfree(ctx);
error_no_ctx:
pkcs7_free_message(msg);
error_no_sig:
return ERR_PTR(ret);
}
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
* @want_wrapper: True if the ASN.1 object header should be included in the data
*
* Get access to the data content of the PKCS#7 message, including, optionally,
* the header of the ASN.1 object that contains it. 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,
bool want_wrapper)
{
size_t wrapper;
if (!pkcs7->data)
return -ENODATA;
wrapper = want_wrapper ? pkcs7->data_hdrlen : 0;
*_data = pkcs7->data - wrapper;
*_data_len = pkcs7->data_len + wrapper;
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.pkey_hash_algo = HASH_ALGO_MD4;
break;
case OID_md5:
ctx->sinfo->sig.pkey_hash_algo = HASH_ALGO_MD5;
break;
case OID_sha1:
ctx->sinfo->sig.pkey_hash_algo = HASH_ALGO_SHA1;
break;
case OID_sha256:
ctx->sinfo->sig.pkey_hash_algo = HASH_ALGO_SHA256;
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 = PKEY_ALGO_RSA;
break;
default:
printk("Unsupported pkey algo: %u\n", ctx->last_oid);
return -ENOPKG;
}
return 0;
}
/*
* 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);
pr_debug("Got cert for %s\n", x509->subject);
pr_debug("- fingerprint %s\n", x509->fingerprint);
x509->index = ++ctx->x509_index;
*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;
}
/*
* 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;
ctx->msg->data_type = ctx->last_oid;
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;
pr_devel("AuthAttr: %02x %zu [%*ph]\n", tag, vlen, (unsigned)vlen, value);
switch (ctx->last_oid) {
case OID_messageDigest:
if (tag != ASN1_OTS)
return -EBADMSG;
ctx->sinfo->msgdigest = value;
ctx->sinfo->msgdigest_len = vlen;
return 0;
default:
return 0;
}
}
/*
* Note the set of auth attributes for digestion purposes [RFC2315 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;
/* We need to switch the 'CONT 0' to a 'SET OF' when we digest */
ctx->sinfo->authattrs = value - (hdrlen - 1);
ctx->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->sinfo->raw_serial = value;
ctx->sinfo->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->sinfo->raw_issuer = value;
ctx->sinfo->raw_issuer_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;
MPI mpi;
BUG_ON(ctx->sinfo->sig.pkey_algo != PKEY_ALGO_RSA);
mpi = mpi_read_raw_data(value, vlen);
if (!mpi)
return -ENOMEM;
ctx->sinfo->sig.mpi[0] = mpi;
ctx->sinfo->sig.nr_mpi = 1;
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;
ctx->sinfo->index = ++ctx->sinfo_index;
*ctx->ppsinfo = ctx->sinfo;
ctx->ppsinfo = &ctx->sinfo->next;
ctx->sinfo = kzalloc(sizeof(struct pkcs7_signed_info), GFP_KERNEL);
if (!ctx->sinfo)
return -ENOMEM;
return 0;
}
/* PKCS#7 crypto data 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 <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 trusted;
/* 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;
/* Issuing cert serial number and issuer's name */
const void *raw_serial;
unsigned raw_serial_size;
unsigned raw_issuer_size;
const void *raw_issuer;
/* 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.
*/
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;
/* 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) */
};
/* PKCS#7 crypto data 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.
*/
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,
bool want_wrapper);
......@@ -55,6 +55,7 @@ enum OID {
OID_certAuthInfoAccess, /* 1.3.6.1.5.5.7.1.1 */
OID_msOutlookExpress, /* 1.3.6.1.4.1.311.16.4 */
OID_sha1, /* 1.3.14.3.2.26 */
OID_sha256, /* 2.16.840.1.101.3.4.2.1 */
/* Distinguished Name attribute IDs [RFC 2256] */
OID_commonName, /* 2.5.4.3 */
......
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