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// SPDX-License-Identifier: GPL-2.0+
/*
* PKCS#7 parser using MbedTLS PKCS#7 library
*
* Copyright (c) 2024 Linaro Limited
* Author: Raymond Mao <raymond.mao@linaro.org>
*/
#include <log.h>
#include <linux/kernel.h>
#include <linux/err.h>
#include <crypto/public_key.h>
#include <crypto/pkcs7_parser.h>
static void pkcs7_free_mbedtls_ctx(struct pkcs7_mbedtls_ctx *ctx)
{
if (ctx) {
kfree(ctx->content_data);
kfree(ctx);
}
}
static void pkcs7_free_sinfo_mbedtls_ctx(struct pkcs7_sinfo_mbedtls_ctx *ctx)
{
if (ctx) {
kfree(ctx->authattrs_data);
kfree(ctx->content_data_digest);
kfree(ctx);
}
}
/*
* Parse Authenticate Attributes
* TODO: Shall we consider to integrate decoding of authenticate attribute into
* MbedTLS library?
*
* There are two kinds of structure for the Authenticate Attributes being used
* in U-Boot.
*
* Type 1 - contains in a PE/COFF EFI image:
*
* [C.P.0] {
* U.P.SEQUENCE {
* U.P.OBJECTIDENTIFIER 1.2.840.113549.1.9.3 (OID_contentType)
* U.P.SET {
* U.P.OBJECTIDENTIFIER 1.3.6.1.4.1.311.2.1.4 (OID_msIndirectData)
* }
* }
* U.P.SEQUENCE {
* U.P.OBJECTIDENTIFIER 1.2.840.113549.1.9.5 (OID_signingTime)
* U.P.SET {
* U.P.UTCTime '<siging_time>'
* }
* }
* U.P.SEQUENCE {
* U.P.OBJECTIDENTIFIER 1.2.840.113549.1.9.4 (OID_messageDigest)
* U.P.SET {
* U.P.OCTETSTRING <digest>
* }
* }
* U.P.SEQUENCE {
* U.P.OBJECTIDENTIFIER 1.2.840.113549.1.9.15 (OID_smimeCapabilites)
* U.P.SET {
* U.P.SEQUENCE {
* <...>
* }
* }
* }
* }
*
* Type 2 - contains in an EFI Capsule:
*
* [C.P.0] {
* U.P.SEQUENCE {
* U.P.OBJECTIDENTIFIER 1.2.840.113549.1.9.3 (OID_contentType)
* U.P.SET {
* U.P.OBJECTIDENTIFIER 1.2.840.113549.1.7.1 (OID_data)
* }
* }
* U.P.SEQUENCE {
* U.P.OBJECTIDENTIFIER 1.2.840.113549.1.9.5 (OID_signingTime)
* U.P.SET {
* U.P.UTCTime '<siging_time>'
* }
* }
* U.P.SEQUENCE {
* U.P.OBJECTIDENTIFIER 1.2.840.113549.1.9.4 (OID_messageDigest)
* U.P.SET {
* U.P.OCTETSTRING <digest>
* }
* }
*}
*
* Note:
* They have different Content Type (OID_msIndirectData or OID_data).
* OID_smimeCapabilites only exists in a PE/COFF EFI image.
*/
static int authattrs_parse(struct pkcs7_message *msg, void *aa, size_t aa_len,
struct pkcs7_signed_info *sinfo)
{
unsigned char *p = aa;
unsigned char *end = (unsigned char *)aa + aa_len;
size_t len = 0;
int ret;
unsigned char *inner_p;
size_t seq_len = 0;
ret = mbedtls_asn1_get_tag(&p, end, &seq_len,
MBEDTLS_ASN1_CONTEXT_SPECIFIC |
MBEDTLS_ASN1_CONSTRUCTED);
if (ret)
return ret;
while (!mbedtls_asn1_get_tag(&p, end, &seq_len,
MBEDTLS_ASN1_CONSTRUCTED |
MBEDTLS_ASN1_SEQUENCE)) {
inner_p = p;
ret = mbedtls_asn1_get_tag(&inner_p, p + seq_len, &len,
MBEDTLS_ASN1_OID);
if (ret)
return ret;
if (!MBEDTLS_OID_CMP_RAW(MBEDTLS_OID_PKCS9_CONTENTTYPE, inner_p, len)) {
inner_p += len;
ret = mbedtls_asn1_get_tag(&inner_p, p + seq_len, &len,
MBEDTLS_ASN1_CONSTRUCTED |
MBEDTLS_ASN1_SET);
if (ret)
return ret;
ret = mbedtls_asn1_get_tag(&inner_p, p + seq_len, &len,
MBEDTLS_ASN1_OID);
if (ret)
return ret;
/*
* We should only support 1.2.840.113549.1.7.1 (OID_data)
* for PKCS7 DATA that is used in EFI Capsule and
* 1.3.6.1.4.1.311.2.1.4 (OID_msIndirectData) for
* MicroSoft Authentication Code that is used in EFI
* Secure Boot.
*/
if (MBEDTLS_OID_CMP_RAW(MBEDTLS_OID_MICROSOFT_INDIRECTDATA,
inner_p, len) &&
MBEDTLS_OID_CMP_RAW(MBEDTLS_OID_PKCS7_DATA,
inner_p, len))
return -EINVAL;
if (__test_and_set_bit(sinfo_has_content_type, &sinfo->aa_set))
return -EINVAL;
} else if (!MBEDTLS_OID_CMP_RAW(MBEDTLS_OID_PKCS9_MESSAGEDIGEST, inner_p,
len)) {
inner_p += len;
ret = mbedtls_asn1_get_tag(&inner_p, p + seq_len, &len,
MBEDTLS_ASN1_CONSTRUCTED |
MBEDTLS_ASN1_SET);
if (ret)
return ret;
ret = mbedtls_asn1_get_tag(&inner_p, p + seq_len, &len,
MBEDTLS_ASN1_OCTET_STRING);
if (ret)
return ret;
sinfo->msgdigest = inner_p;
sinfo->msgdigest_len = len;
if (__test_and_set_bit(sinfo_has_message_digest, &sinfo->aa_set))
return -EINVAL;
} else if (!MBEDTLS_OID_CMP_RAW(MBEDTLS_OID_PKCS9_SIGNINGTIME, inner_p,
len)) {
mbedtls_x509_time st;
inner_p += len;
ret = mbedtls_asn1_get_tag(&inner_p, p + seq_len, &len,
MBEDTLS_ASN1_CONSTRUCTED |
MBEDTLS_ASN1_SET);
if (ret)
return ret;
ret = mbedtls_x509_get_time(&inner_p, p + seq_len, &st);
if (ret)
return ret;
sinfo->signing_time = x509_get_timestamp(&st);
if (__test_and_set_bit(sinfo_has_signing_time, &sinfo->aa_set))
return -EINVAL;
} else if (!MBEDTLS_OID_CMP_RAW(MBEDTLS_OID_PKCS9_SMIMECAP, inner_p,
len)) {
if (__test_and_set_bit(sinfo_has_smime_caps, &sinfo->aa_set))
return -EINVAL;
if (msg->data_type != OID_msIndirectData &&
msg->data_type != OID_data)
return -EINVAL;
} else if (!MBEDTLS_OID_CMP_RAW(MBEDTLS_OID_MICROSOFT_SPOPUSINFO, inner_p,
len)) {
if (__test_and_set_bit(sinfo_has_ms_opus_info, &sinfo->aa_set))
return -EINVAL;
} else if (!MBEDTLS_OID_CMP_RAW(MBEDTLS_OID_MICROSOFT_STATETYPE, inner_p,
len)) {
if (__test_and_set_bit(sinfo_has_ms_statement_type, &sinfo->aa_set))
return -EINVAL;
}
p += seq_len;
}
msg->have_authattrs = true;
/*
* Skip the leading tag byte (MBEDTLS_ASN1_CONTEXT_SPECIFIC |
* MBEDTLS_ASN1_CONSTRUCTED) to satisfy pkcs7_digest() when calculating
* the digest of authattrs.
*/
sinfo->authattrs = aa + 1;
sinfo->authattrs_len = aa_len - 1;
return 0;
}
static int x509_populate_content_data(struct pkcs7_message *msg,
mbedtls_pkcs7 *pkcs7_ctx)
{
struct pkcs7_mbedtls_ctx *mctx;
if (!pkcs7_ctx->content_data.data ||
!pkcs7_ctx->content_data.data_len)
return 0;
mctx = kzalloc(sizeof(*mctx), GFP_KERNEL);
if (!mctx)
return -ENOMEM;
mctx->content_data = kmemdup(pkcs7_ctx->content_data.data,
pkcs7_ctx->content_data.data_len,
GFP_KERNEL);
if (!mctx->content_data) {
pkcs7_free_mbedtls_ctx(mctx);
return -ENOMEM;
}
msg->data = mctx->content_data;
msg->data_len = pkcs7_ctx->content_data.data_len;
msg->data_hdrlen = pkcs7_ctx->content_data.data_hdrlen;
msg->data_type = pkcs7_ctx->content_data.data_type;
msg->mbedtls_ctx = mctx;
return 0;
}
static int x509_populate_sinfo(struct pkcs7_message *msg,
mbedtls_pkcs7_signer_info *mb_sinfo,
struct pkcs7_signed_info **sinfo)
{
struct pkcs7_signed_info *signed_info;
struct public_key_signature *s;
mbedtls_md_type_t md_alg;
struct pkcs7_sinfo_mbedtls_ctx *mctx;
int ret;
signed_info = kzalloc(sizeof(*signed_info), GFP_KERNEL);
if (!signed_info)
return -ENOMEM;
s = kzalloc(sizeof(*s), GFP_KERNEL);
if (!s) {
ret = -ENOMEM;
goto out_no_sig;
}
mctx = kzalloc(sizeof(*mctx), GFP_KERNEL);
if (!mctx) {
ret = -ENOMEM;
goto out_no_mctx;
}
/*
* Hash algorithm:
*
* alg_identifier = digestAlgorithm (DigestAlgorithmIdentifier)
* MbedTLS internally checks this field to ensure
* it is the same as digest_alg_identifiers.
* sig_alg_identifier = digestEncryptionAlgorithm
* (DigestEncryptionAlgorithmIdentifier)
* MbedTLS just saves this field without any actions.
* See function pkcs7_get_signer_info() for reference.
*
* Public key algorithm:
* No information related to public key algorithm under MbedTLS signer
* info. Assume that we are using RSA.
*/
ret = mbedtls_oid_get_md_alg(&mb_sinfo->alg_identifier, &md_alg);
if (ret)
goto out_err_sinfo;
s->pkey_algo = "rsa";
/* Translate the hash algorithm */
switch (md_alg) {
case MBEDTLS_MD_SHA1:
s->hash_algo = "sha1";
s->digest_size = SHA1_SUM_LEN;
break;
case MBEDTLS_MD_SHA256:
s->hash_algo = "sha256";
s->digest_size = SHA256_SUM_LEN;
break;
case MBEDTLS_MD_SHA384:
s->hash_algo = "sha384";
s->digest_size = SHA384_SUM_LEN;
break;
case MBEDTLS_MD_SHA512:
s->hash_algo = "sha512";
s->digest_size = SHA512_SUM_LEN;
break;
/* Unsupported algo */
case MBEDTLS_MD_MD5:
case MBEDTLS_MD_SHA224:
default:
ret = -EINVAL;
goto out_err_sinfo;
}
/*
* auth_ids holds AuthorityKeyIdentifier, aka akid
* auth_ids[0]:
* [PKCS#7 or CMS ver 1] - generated from "Issuer + Serial number"
* [CMS ver 3] - generated from skid (subjectKeyId)
* auth_ids[1]: generated from skid (subjectKeyId)
*
* Assume that we are using PKCS#7 (msg->version=1),
* not CMS ver 3 (msg->version=3).
*/
s->auth_ids[0] = asymmetric_key_generate_id(mb_sinfo->serial.p,
mb_sinfo->serial.len,
mb_sinfo->issuer_raw.p,
mb_sinfo->issuer_raw.len);
if (!s->auth_ids[0]) {
ret = -ENOMEM;
goto out_err_sinfo;
}
/* skip s->auth_ids[1], no subjectKeyId in MbedTLS signer info ctx */
/*
* Encoding can be pkcs1 or raw, but only pkcs1 is supported.
* Set the encoding explicitly to pkcs1.
*/
s->encoding = "pkcs1";
/* Copy the signature data */
s->s = kmemdup(mb_sinfo->sig.p, mb_sinfo->sig.len, GFP_KERNEL);
if (!s->s) {
ret = -ENOMEM;
goto out_err_sinfo;
}
s->s_size = mb_sinfo->sig.len;
signed_info->sig = s;
/* Save the Authenticate Attributes data if exists */
if (!mb_sinfo->authattrs.data || !mb_sinfo->authattrs.data_len) {
kfree(mctx);
goto no_authattrs;
}
mctx->authattrs_data = kmemdup(mb_sinfo->authattrs.data,
mb_sinfo->authattrs.data_len,
GFP_KERNEL);
if (!mctx->authattrs_data) {
ret = -ENOMEM;
goto out_err_sinfo;
}
signed_info->mbedtls_ctx = mctx;
/* If authattrs exists, decode it and parse msgdigest from it */
ret = authattrs_parse(msg, mctx->authattrs_data,
mb_sinfo->authattrs.data_len,
signed_info);
if (ret)
goto out_err_sinfo;
no_authattrs:
*sinfo = signed_info;
return 0;
out_err_sinfo:
pkcs7_free_sinfo_mbedtls_ctx(mctx);
out_no_mctx:
public_key_signature_free(s);
out_no_sig:
kfree(signed_info);
return ret;
}
/*
* Free a signed information block.
*/
static void pkcs7_free_signed_info(struct pkcs7_signed_info *sinfo)
{
if (sinfo) {
public_key_signature_free(sinfo->sig);
pkcs7_free_sinfo_mbedtls_ctx(sinfo->mbedtls_ctx);
kfree(sinfo);
}
}
/**
* 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;
pkcs7_free_signed_info(sinfo);
}
pkcs7_free_mbedtls_ctx(pkcs7->mbedtls_ctx);
kfree(pkcs7);
}
}
struct pkcs7_message *pkcs7_parse_message(const void *data, size_t datalen)
{
int i;
int ret;
mbedtls_pkcs7 pkcs7_ctx;
mbedtls_pkcs7_signer_info *mb_sinfos;
mbedtls_x509_crt *mb_certs;
struct pkcs7_message *msg;
struct x509_certificate **cert;
struct pkcs7_signed_info **sinfos;
msg = kzalloc(sizeof(*msg), GFP_KERNEL);
if (!msg) {
ret = -ENOMEM;
goto out_no_msg;
}
/* Parse the DER encoded PKCS#7 message using MbedTLS */
mbedtls_pkcs7_init(&pkcs7_ctx);
ret = mbedtls_pkcs7_parse_der(&pkcs7_ctx, data, datalen);
/* Check if it is a PKCS#7 message with signed data */
if (ret != MBEDTLS_PKCS7_SIGNED_DATA)
goto parse_fail;
/* Assume that we are using PKCS#7, not CMS ver 3 */
msg->version = 1; /* 1 for [PKCS#7 or CMS ver 1] */
/* Populate the certs to msg->certs */
for (i = 0, cert = &msg->certs, mb_certs = &pkcs7_ctx.signed_data.certs;
i < pkcs7_ctx.signed_data.no_of_certs && mb_certs;
i++, cert = &(*cert)->next, mb_certs = mb_certs->next) {
ret = x509_populate_cert(mb_certs, cert);
if (ret)
goto parse_fail;
(*cert)->index = i + 1;
}
/*
* Skip populating crl, that is not currently in-use.
*/
/* Populate content data */
ret = x509_populate_content_data(msg, &pkcs7_ctx);
if (ret)
goto parse_fail;
/* Populate signed info to msg->signed_infos */
for (i = 0, sinfos = &msg->signed_infos,
mb_sinfos = &pkcs7_ctx.signed_data.signers;
i < pkcs7_ctx.signed_data.no_of_signers && mb_sinfos;
i++, sinfos = &(*sinfos)->next, mb_sinfos = mb_sinfos->next) {
ret = x509_populate_sinfo(msg, mb_sinfos, sinfos);
if (ret)
goto parse_fail;
(*sinfos)->index = i + 1;
}
mbedtls_pkcs7_free(&pkcs7_ctx);
return msg;
parse_fail:
mbedtls_pkcs7_free(&pkcs7_ctx);
pkcs7_free_message(msg);
out_no_msg:
msg = ERR_PTR(ret);
return msg;
}
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