| // 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; |
| } |