// SPDX-License-Identifier: GPL-2.0-or-later /* PKCS#7 parser * * Copyright (C) 2012 Red Hat, Inc. All Rights Reserved. * Written by David Howells (dhowells@redhat.com) */ #define pr_fmt(fmt) "PKCS7: "fmt #include <linux/kernel.h> #include <linux/module.h> #include <linux/export.h> #include <linux/slab.h> #include <linux/err.h> #include <linux/oid_registry.h> #include <crypto/public_key.h> #include "pkcs7_parser.h" #include "pkcs7.asn1.h" MODULE_DESCRIPTION("PKCS#7 parser"); MODULE_AUTHOR("Red Hat, Inc."); MODULE_LICENSE("GPL"); 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; const void *raw_serial; unsigned raw_serial_size; unsigned raw_issuer_size; const void *raw_issuer; const void *raw_skid; unsigned raw_skid_size; bool expect_skid; }; /* * Free a signed information block. */ static void pkcs7_free_signed_info(struct pkcs7_signed_info *sinfo) { if (sinfo) { public_key_signature_free(sinfo->sig); 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); } kfree(pkcs7); } } EXPORT_SYMBOL_GPL(pkcs7_free_message); /* * Check authenticatedAttributes are provided or not provided consistently. */ static int pkcs7_check_authattrs(struct pkcs7_message *msg) { struct pkcs7_signed_info *sinfo; bool want = false; sinfo = msg->signed_infos; if (!sinfo) goto inconsistent; if (sinfo->authattrs) { want = true; msg->have_authattrs = true; } for (sinfo = sinfo->next; sinfo; sinfo = sinfo->next) if (!!sinfo->authattrs != want) goto inconsistent; return 0; inconsistent: pr_warn("Inconsistently supplied authAttrs\n"); return -EINVAL; } /** * 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 = ERR_PTR(-ENOMEM); int ret; ctx = kzalloc(sizeof(struct pkcs7_parse_context), GFP_KERNEL); if (!ctx) goto out_no_ctx; ctx->msg = kzalloc(sizeof(struct pkcs7_message), GFP_KERNEL); if (!ctx->msg) goto out_no_msg; ctx->sinfo = kzalloc(sizeof(struct pkcs7_signed_info), GFP_KERNEL); if (!ctx->sinfo) goto out_no_sinfo; ctx->sinfo->sig = kzalloc(sizeof(struct public_key_signature), GFP_KERNEL); if (!ctx->sinfo->sig) goto out_no_sig; 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) { msg = ERR_PTR(ret); goto out; } ret = pkcs7_check_authattrs(ctx->msg); if (ret < 0) { msg = ERR_PTR(ret); goto out; } msg = ctx->msg; ctx->msg = NULL; out: while (ctx->certs) { struct x509_certificate *cert = ctx->certs; ctx->certs = cert->next; x509_free_certificate(cert); } out_no_sig: pkcs7_free_signed_info(ctx->sinfo); out_no_sinfo: pkcs7_free_message(ctx->msg); out_no_msg: kfree(ctx); out_no_ctx: return msg; } 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 * @_headerlen: Size of ASN.1 header not included in _data * * Get access to the data content of the PKCS#7 message. The size of the * header of the ASN.1 object that contains it is also provided and can be used * to adjust *_data and *_data_len to get the entire object. * * 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, size_t *_headerlen) { if (!pkcs7->data) return -ENODATA; *_data = pkcs7->data; *_data_len = pkcs7->data_len; if (_headerlen) *_headerlen = pkcs7->data_hdrlen; 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->hash_algo = "md4"; break; case OID_md5: ctx->sinfo->sig->hash_algo = "md5"; break; case OID_sha1: ctx->sinfo->sig->hash_algo = "sha1"; break; case OID_sha256: ctx->sinfo->sig->hash_algo = "sha256"; break; case OID_sha384: ctx->sinfo->sig->hash_algo = "sha384"; break; case OID_sha512: ctx->sinfo->sig->hash_algo = "sha512"; break; case OID_sha224: ctx->sinfo->sig->hash_algo = "sha224"; 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 = "rsa"; ctx->sinfo->sig->encoding = "pkcs1"; break; default: printk("Unsupported pkey algo: %u\n", ctx->last_oid); return -ENOPKG; } return 0; } /* * We only support signed data [RFC2315 sec 9]. */ int pkcs7_check_content_type(void *context, size_t hdrlen, unsigned char tag, const void *value, size_t vlen) { struct pkcs7_parse_context *ctx = context; if (ctx->last_oid != OID_signed_data) { pr_warn("Only support pkcs7_signedData type\n"); return -EINVAL; } return 0; } /* * Note the SignedData version */ int pkcs7_note_signeddata_version(void *context, size_t hdrlen, unsigned char tag, const void *value, size_t vlen) { struct pkcs7_parse_context *ctx = context; unsigned version; if (vlen != 1) goto unsupported; ctx->msg->version = version = *(const u8 *)value; switch (version) { case 1: /* PKCS#7 SignedData [RFC2315 sec 9.1] * CMS ver 1 SignedData [RFC5652 sec 5.1] */ break; case 3: /* CMS ver 3 SignedData [RFC2315 sec 5.1] */ break; default: goto unsupported; } return 0; unsupported: pr_warn("Unsupported SignedData version\n"); return -EINVAL; } /* * Note the SignerInfo version */ int pkcs7_note_signerinfo_version(void *context, size_t hdrlen, unsigned char tag, const void *value, size_t vlen) { struct pkcs7_parse_context *ctx = context; unsigned version; if (vlen != 1) goto unsupported; version = *(const u8 *)value; switch (version) { case 1: /* PKCS#7 SignerInfo [RFC2315 sec 9.2] * CMS ver 1 SignerInfo [RFC5652 sec 5.3] */ if (ctx->msg->version != 1) goto version_mismatch; ctx->expect_skid = false; break; case 3: /* CMS ver 3 SignerInfo [RFC2315 sec 5.3] */ if (ctx->msg->version == 1) goto version_mismatch; ctx->expect_skid = true; break; default: goto unsupported; } return 0; unsupported: pr_warn("Unsupported SignerInfo version\n"); return -EINVAL; version_mismatch: pr_warn("SignedData-SignerInfo version mismatch\n"); return -EBADMSG; } /* * 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); x509->index = ++ctx->x509_index; pr_debug("Got cert %u for %s\n", x509->index, x509->subject); pr_debug("- fingerprint %*phN\n", x509->id->len, x509->id->data); *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; } /* * Note the content type. */ int pkcs7_note_content(void *context, size_t hdrlen, unsigned char tag, const void *value, size_t vlen) { struct pkcs7_parse_context *ctx = context; if (ctx->last_oid != OID_data && ctx->last_oid != OID_msIndirectData) { pr_warn("Unsupported data type %d\n", ctx->last_oid); return -EINVAL; } ctx->msg->data_type = ctx->last_oid; 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; 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; struct pkcs7_signed_info *sinfo = ctx->sinfo; enum OID content_type; pr_devel("AuthAttr: %02x %zu [%*ph]\n", tag, vlen, (unsigned)vlen, value); switch (ctx->last_oid) { case OID_contentType: if (__test_and_set_bit(sinfo_has_content_type, &sinfo->aa_set)) goto repeated; content_type = look_up_OID(value, vlen); if (content_type != ctx->msg->data_type) { pr_warn("Mismatch between global data type (%d) and sinfo %u (%d)\n", ctx->msg->data_type, sinfo->index, content_type); return -EBADMSG; } return 0; case OID_signingTime: if (__test_and_set_bit(sinfo_has_signing_time, &sinfo->aa_set)) goto repeated; /* Should we check that the signing time is consistent * with the signer's X.509 cert? */ return x509_decode_time(&sinfo->signing_time, hdrlen, tag, value, vlen); case OID_messageDigest: if (__test_and_set_bit(sinfo_has_message_digest, &sinfo->aa_set)) goto repeated; if (tag != ASN1_OTS) return -EBADMSG; sinfo->msgdigest = value; sinfo->msgdigest_len = vlen; return 0; case OID_smimeCapabilites: if (__test_and_set_bit(sinfo_has_smime_caps, &sinfo->aa_set)) goto repeated; if (ctx->msg->data_type != OID_msIndirectData) { pr_warn("S/MIME Caps only allowed with Authenticode\n"); return -EKEYREJECTED; } return 0; /* Microsoft SpOpusInfo seems to be contain cont[0] 16-bit BE * char URLs and cont[1] 8-bit char URLs. * * Microsoft StatementType seems to contain a list of OIDs that * are also used as extendedKeyUsage types in X.509 certs. */ case OID_msSpOpusInfo: if (__test_and_set_bit(sinfo_has_ms_opus_info, &sinfo->aa_set)) goto repeated; goto authenticode_check; case OID_msStatementType: if (__test_and_set_bit(sinfo_has_ms_statement_type, &sinfo->aa_set)) goto repeated; authenticode_check: if (ctx->msg->data_type != OID_msIndirectData) { pr_warn("Authenticode AuthAttrs only allowed with Authenticode\n"); return -EKEYREJECTED; } /* I'm not sure how to validate these */ return 0; default: return 0; } repeated: /* We permit max one item per AuthenticatedAttribute and no repeats */ pr_warn("Repeated/multivalue AuthAttrs not permitted\n"); return -EKEYREJECTED; } /* * Note the set of auth attributes for digestion purposes [RFC2315 sec 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; struct pkcs7_signed_info *sinfo = ctx->sinfo; if (!test_bit(sinfo_has_content_type, &sinfo->aa_set) || !test_bit(sinfo_has_message_digest, &sinfo->aa_set)) { pr_warn("Missing required AuthAttr\n"); return -EBADMSG; } if (ctx->msg->data_type != OID_msIndirectData && test_bit(sinfo_has_ms_opus_info, &sinfo->aa_set)) { pr_warn("Unexpected Authenticode AuthAttr\n"); return -EBADMSG; } /* We need to switch the 'CONT 0' to a 'SET OF' when we digest */ sinfo->authattrs = value - (hdrlen - 1); 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->raw_serial = value; ctx->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->raw_issuer = value; ctx->raw_issuer_size = vlen; return 0; } /* * Note the issuing cert's subjectKeyIdentifier */ int pkcs7_sig_note_skid(void *context, size_t hdrlen, unsigned char tag, const void *value, size_t vlen) { struct pkcs7_parse_context *ctx = context; pr_devel("SKID: %02x %zu [%*ph]\n", tag, vlen, (unsigned)vlen, value); ctx->raw_skid = value; ctx->raw_skid_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; ctx->sinfo->sig->s = kmemdup(value, vlen, GFP_KERNEL); if (!ctx->sinfo->sig->s) return -ENOMEM; ctx->sinfo->sig->s_size = vlen; 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; struct pkcs7_signed_info *sinfo = ctx->sinfo; struct asymmetric_key_id *kid; if (ctx->msg->data_type == OID_msIndirectData && !sinfo->authattrs) { pr_warn("Authenticode requires AuthAttrs\n"); return -EBADMSG; } /* Generate cert issuer + serial number key ID */ if (!ctx->expect_skid) { kid = asymmetric_key_generate_id(ctx->raw_serial, ctx->raw_serial_size, ctx->raw_issuer, ctx->raw_issuer_size); } else { kid = asymmetric_key_generate_id(ctx->raw_skid, ctx->raw_skid_size, "", 0); } if (IS_ERR(kid)) return PTR_ERR(kid); pr_devel("SINFO KID: %u [%*phN]\n", kid->len, kid->len, kid->data); sinfo->sig->auth_ids[0] = kid; sinfo->index = ++ctx->sinfo_index; *ctx->ppsinfo = sinfo; ctx->ppsinfo = &sinfo->next; ctx->sinfo = kzalloc(sizeof(struct pkcs7_signed_info), GFP_KERNEL); if (!ctx->sinfo) return -ENOMEM; ctx->sinfo->sig = kzalloc(sizeof(struct public_key_signature), GFP_KERNEL); if (!ctx->sinfo->sig) return -ENOMEM; return 0; }