--- /dev/null
+// 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;
+ }
+
+ if (ret && ret != MBEDTLS_ERR_ASN1_OUT_OF_DATA)
+ return ret;
+
+ 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)
+ 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;
+}
projects / u-boot.git / commitdiff