/* 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 <crypto/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;

  	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
  ");
  	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)
  		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
  ",
  		       (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
  ", 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";

  		break;
  	default:
  		printk("Unsupported pkey algo: %u
  ", 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
  ");
  		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
  ");
  	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
  ");
  	return -EINVAL;

  version_mismatch:
  	pr_warn("SignedData-SignerInfo version mismatch
  ");
  	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
  ",
  			 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
  ", x509->index, x509->subject);
  	pr_debug("- fingerprint %*phN
  ", 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)
  ", 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
  ", 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
  ");
  
  	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]
  ", 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)
  ",
  				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
  ");
  			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
  ");
  			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
  ");
  	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
  ");
  		return -EBADMSG;
  	}
  
  	if (ctx->msg->data_type != OID_msIndirectData &&
  	    test_bit(sinfo_has_ms_opus_info, &sinfo->aa_set)) {
  		pr_warn("Unexpected Authenticode AuthAttr
  ");
  		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]
  ", 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
  ");
  		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]
  ", 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;
  }