/*

 * Written by Dr Stephen N Henson (steve@openssl.org) for the OpenSSL

 * project.

 */

/* ====================================================================

 * Copyright (c) 2003 The OpenSSL Project.  All rights reserved.

 *

 * Redistribution and use in source and binary forms, with or without

 * modification, are permitted provided that the following conditions

 * are met:

 *

 * 1. Redistributions of source code must retain the above copyright

 *    notice, this list of conditions and the following disclaimer.

 *

 * 2. Redistributions in binary form must reproduce the above copyright

 *    notice, this list of conditions and the following disclaimer in

 *    the documentation and/or other materials provided with the

 *    distribution.

 *

 * 3. All advertising materials mentioning features or use of this

 *    software must display the following acknowledgment:

 *    "This product includes software developed by the OpenSSL Project

 *    for use in the OpenSSL Toolkit. (http://www.OpenSSL.org/)"

 *

 * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to

 *    endorse or promote products derived from this software without

 *    prior written permission. For written permission, please contact

 *    licensing@OpenSSL.org.

 *

 * 5. Products derived from this software may not be called "OpenSSL"

 *    nor may "OpenSSL" appear in their names without prior written

 *    permission of the OpenSSL Project.

 *

 * 6. Redistributions of any form whatsoever must retain the following

 *    acknowledgment:

 *    "This product includes software developed by the OpenSSL Project

 *    for use in the OpenSSL Toolkit (http://www.OpenSSL.org/)"

 *

 * THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY

 * EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE

 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR

 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE OpenSSL PROJECT OR

 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,

 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT

 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;

 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)

 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,

 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)

 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED

 * OF THE POSSIBILITY OF SUCH DAMAGE.

 * ====================================================================

 *

 * This product includes cryptographic software written by Eric Young

 * (eay@cryptsoft.com).  This product includes software written by Tim

 * Hudson (tjh@cryptsoft.com). */

#include <stdio.h>

#include <string.h>

#include <openssl/asn1t.h>

#include <openssl/conf.h>

#include <openssl/err.h>

#include <openssl/mem.h>

#include <openssl/obj.h>

#include <openssl/x509v3.h>

#include "../internal.h"

#include "../x509/internal.h"

static void *v2i_NAME_CONSTRAINTS(const X509V3_EXT_METHOD *method,

                                  const X509V3_CTX *ctx,

                                  const STACK_OF(CONF_VALUE) *nval);

static int i2r_NAME_CONSTRAINTS(const X509V3_EXT_METHOD *method, void *a,

                                BIO *bp, int ind);

static int do_i2r_name_constraints(const X509V3_EXT_METHOD *method,

                                   STACK_OF(GENERAL_SUBTREE) *trees, BIO *bp,

                                   int ind, const char *name);

static int print_nc_ipadd(BIO *bp, const ASN1_OCTET_STRING *ip);

static int nc_match(GENERAL_NAME *gen, NAME_CONSTRAINTS *nc);

static int nc_match_single(GENERAL_NAME *sub, GENERAL_NAME *gen);

static int nc_dn(X509_NAME *sub, X509_NAME *nm);

static int nc_dns(const ASN1_IA5STRING *sub, const ASN1_IA5STRING *dns);

static int nc_email(const ASN1_IA5STRING *sub, const ASN1_IA5STRING *eml);

static int nc_uri(const ASN1_IA5STRING *uri, const ASN1_IA5STRING *base);

const X509V3_EXT_METHOD v3_name_constraints = {

    NID_name_constraints,

    0,

    ASN1_ITEM_ref(NAME_CONSTRAINTS),

    0,

    0,

    0,

    0,

    0,

    0,

    0,

    v2i_NAME_CONSTRAINTS,

    i2r_NAME_CONSTRAINTS,

    0,

    NULL,

};

ASN1_SEQUENCE(GENERAL_SUBTREE) = {

    ASN1_SIMPLE(GENERAL_SUBTREE, base, GENERAL_NAME),

    ASN1_IMP_OPT(GENERAL_SUBTREE, minimum, ASN1_INTEGER, 0),

    ASN1_IMP_OPT(GENERAL_SUBTREE, maximum, ASN1_INTEGER, 1),

} ASN1_SEQUENCE_END(GENERAL_SUBTREE)

ASN1_SEQUENCE(NAME_CONSTRAINTS) = {

    ASN1_IMP_SEQUENCE_OF_OPT(NAME_CONSTRAINTS, permittedSubtrees,

                             GENERAL_SUBTREE, 0),

    ASN1_IMP_SEQUENCE_OF_OPT(NAME_CONSTRAINTS, excludedSubtrees,

                             GENERAL_SUBTREE, 1),

} ASN1_SEQUENCE_END(NAME_CONSTRAINTS)

IMPLEMENT_ASN1_ALLOC_FUNCTIONS(GENERAL_SUBTREE)

IMPLEMENT_ASN1_ALLOC_FUNCTIONS(NAME_CONSTRAINTS)

static void *v2i_NAME_CONSTRAINTS(const X509V3_EXT_METHOD *method,

                                  const X509V3_CTX *ctx,

                                  const STACK_OF(CONF_VALUE) *nval) {

  STACK_OF(GENERAL_SUBTREE) **ptree = NULL;

  NAME_CONSTRAINTS *ncons = NULL;

  GENERAL_SUBTREE *sub = NULL;

  ncons = NAME_CONSTRAINTS_new();

  if (!ncons) {

    goto err;

  }

  for (size_t i = 0; i < sk_CONF_VALUE_num(nval); i++) {

    const CONF_VALUE *val = sk_CONF_VALUE_value(nval, i);

    CONF_VALUE tval;

    if (!strncmp(val->name, "permitted", 9) && val->name[9]) {

      ptree = &ncons->permittedSubtrees;

      tval.name = val->name + 10;

    } else if (!strncmp(val->name, "excluded", 8) && val->name[8]) {

      ptree = &ncons->excludedSubtrees;

      tval.name = val->name + 9;

    } else {

      OPENSSL_PUT_ERROR(X509V3, X509V3_R_INVALID_SYNTAX);

      goto err;

    }

    tval.value = val->value;

    sub = GENERAL_SUBTREE_new();

    if (!v2i_GENERAL_NAME_ex(sub->base, method, ctx, &tval, 1)) {

      goto err;

    }

    if (!*ptree) {

      *ptree = sk_GENERAL_SUBTREE_new_null();

    }

    if (!*ptree || !sk_GENERAL_SUBTREE_push(*ptree, sub)) {

      goto err;

    }

    sub = NULL;

  }

  return ncons;

err:

  NAME_CONSTRAINTS_free(ncons);

  GENERAL_SUBTREE_free(sub);

  return NULL;

}

static int i2r_NAME_CONSTRAINTS(const X509V3_EXT_METHOD *method, void *a,

                                BIO *bp, int ind) {

  NAME_CONSTRAINTS *ncons = a;

  do_i2r_name_constraints(method, ncons->permittedSubtrees, bp, ind,

                          "Permitted");

  do_i2r_name_constraints(method, ncons->excludedSubtrees, bp, ind, "Excluded");

  return 1;

}

static int do_i2r_name_constraints(const X509V3_EXT_METHOD *method,

                                   STACK_OF(GENERAL_SUBTREE) *trees, BIO *bp,

                                   int ind, const char *name) {

  GENERAL_SUBTREE *tree;

  size_t i;

  if (sk_GENERAL_SUBTREE_num(trees) > 0) {

    BIO_printf(bp, "%*s%s:\n", ind, "", name);

  }

  for (i = 0; i < sk_GENERAL_SUBTREE_num(trees); i++) {

    tree = sk_GENERAL_SUBTREE_value(trees, i);

    BIO_printf(bp, "%*s", ind + 2, "");

    if (tree->base->type == GEN_IPADD) {

      print_nc_ipadd(bp, tree->base->d.ip);

    } else {

      GENERAL_NAME_print(bp, tree->base);

    }

    BIO_puts(bp, "\n");

  }

  return 1;

}

static int print_nc_ipadd(BIO *bp, const ASN1_OCTET_STRING *ip) {

  int i, len;

  unsigned char *p;

  p = ip->data;

  len = ip->length;

  BIO_puts(bp, "IP:");

  if (len == 8) {

    BIO_printf(bp, "%d.%d.%d.%d/%d.%d.%d.%d", p[0], p[1], p[2], p[3], p[4],

               p[5], p[6], p[7]);

  } else if (len == 32) {

    for (i = 0; i < 16; i++) {

      uint16_t v = ((uint16_t)p[0] << 8) | p[1];

      BIO_printf(bp, "%X", v);

      p += 2;

      if (i == 7) {

        BIO_puts(bp, "/");

      } else if (i != 15) {

        BIO_puts(bp, ":");

      }

    }

  } else {

    BIO_printf(bp, "IP Address:<invalid>");

  }

  return 1;

}

//-

// Check a certificate conforms to a specified set of constraints.

// Return values:

//   X509_V_OK: All constraints obeyed.

//   X509_V_ERR_PERMITTED_VIOLATION: Permitted subtree violation.

//   X509_V_ERR_EXCLUDED_VIOLATION: Excluded subtree violation.

//   X509_V_ERR_SUBTREE_MINMAX: Min or max values present and matching type.

//   X509_V_ERR_UNSPECIFIED: Unspecified error.

//   X509_V_ERR_UNSUPPORTED_CONSTRAINT_TYPE: Unsupported constraint type.

//   X509_V_ERR_UNSUPPORTED_CONSTRAINT_SYNTAX: Bad or unsupported constraint

//     syntax.

//   X509_V_ERR_UNSUPPORTED_NAME_SYNTAX: Bad or unsupported syntax of name.

int NAME_CONSTRAINTS_check(X509 *x, NAME_CONSTRAINTS *nc) {

  int r, i;

  size_t j;

  X509_NAME *nm;

  nm = X509_get_subject_name(x);

  // Guard against certificates with an excessive number of names or

  // constraints causing a computationally expensive name constraints

  // check.

  size_t name_count =

      X509_NAME_entry_count(nm) + sk_GENERAL_NAME_num(x->altname);

  size_t constraint_count = sk_GENERAL_SUBTREE_num(nc->permittedSubtrees) +

                            sk_GENERAL_SUBTREE_num(nc->excludedSubtrees);

  size_t check_count = constraint_count * name_count;

  if (name_count < (size_t)X509_NAME_entry_count(nm) ||

      constraint_count < sk_GENERAL_SUBTREE_num(nc->permittedSubtrees) ||

      (constraint_count && check_count / constraint_count != name_count) ||

      check_count > 1 << 20) {

    return X509_V_ERR_UNSPECIFIED;

  }

  if (X509_NAME_entry_count(nm) > 0) {

    GENERAL_NAME gntmp;

    gntmp.type = GEN_DIRNAME;

    gntmp.d.directoryName = nm;

    r = nc_match(&gntmp, nc);

    if (r != X509_V_OK) {

      return r;

    }

    gntmp.type = GEN_EMAIL;

    // Process any email address attributes in subject name

    for (i = -1;;) {

      i = X509_NAME_get_index_by_NID(nm, NID_pkcs9_emailAddress, i);

      if (i == -1) {

        break;

      }

      const X509_NAME_ENTRY *ne = X509_NAME_get_entry(nm, i);

      gntmp.d.rfc822Name = X509_NAME_ENTRY_get_data(ne);

      if (gntmp.d.rfc822Name->type != V_ASN1_IA5STRING) {

        return X509_V_ERR_UNSUPPORTED_NAME_SYNTAX;

      }

      r = nc_match(&gntmp, nc);

      if (r != X509_V_OK) {

        return r;

      }

    }

  }

  for (j = 0; j < sk_GENERAL_NAME_num(x->altname); j++) {

    GENERAL_NAME *gen = sk_GENERAL_NAME_value(x->altname, j);

    r = nc_match(gen, nc);

    if (r != X509_V_OK) {

      return r;

    }

  }

  return X509_V_OK;

}

static int nc_match(GENERAL_NAME *gen, NAME_CONSTRAINTS *nc) {

  GENERAL_SUBTREE *sub;

  int r, match = 0;

  size_t i;

  // Permitted subtrees: if any subtrees exist of matching the type at

  // least one subtree must match.

  for (i = 0; i < sk_GENERAL_SUBTREE_num(nc->permittedSubtrees); i++) {

    sub = sk_GENERAL_SUBTREE_value(nc->permittedSubtrees, i);

    if (gen->type != sub->base->type) {

      continue;

    }

    if (sub->minimum || sub->maximum) {

      return X509_V_ERR_SUBTREE_MINMAX;

    }

    // If we already have a match don't bother trying any more

    if (match == 2) {

      continue;

    }

    if (match == 0) {

      match = 1;

    }

    r = nc_match_single(gen, sub->base);

    if (r == X509_V_OK) {

      match = 2;

    } else if (r != X509_V_ERR_PERMITTED_VIOLATION) {

      return r;

    }

  }

  if (match == 1) {

    return X509_V_ERR_PERMITTED_VIOLATION;

  }

  // Excluded subtrees: must not match any of these

  for (i = 0; i < sk_GENERAL_SUBTREE_num(nc->excludedSubtrees); i++) {

    sub = sk_GENERAL_SUBTREE_value(nc->excludedSubtrees, i);

    if (gen->type != sub->base->type) {

      continue;

    }

    if (sub->minimum || sub->maximum) {

      return X509_V_ERR_SUBTREE_MINMAX;

    }

    r = nc_match_single(gen, sub->base);

    if (r == X509_V_OK) {

      return X509_V_ERR_EXCLUDED_VIOLATION;

    } else if (r != X509_V_ERR_PERMITTED_VIOLATION) {

      return r;

    }

  }

  return X509_V_OK;

}

static int nc_match_single(GENERAL_NAME *gen, GENERAL_NAME *base) {

  switch (base->type) {

    case GEN_DIRNAME:

      return nc_dn(gen->d.directoryName, base->d.directoryName);

    case GEN_DNS:

      return nc_dns(gen->d.dNSName, base->d.dNSName);

    case GEN_EMAIL:

      return nc_email(gen->d.rfc822Name, base->d.rfc822Name);

    case GEN_URI:

      return nc_uri(gen->d.uniformResourceIdentifier,

                    base->d.uniformResourceIdentifier);

    default:

      return X509_V_ERR_UNSUPPORTED_CONSTRAINT_TYPE;

  }

}

// directoryName name constraint matching. The canonical encoding of

// X509_NAME makes this comparison easy. It is matched if the subtree is a

// subset of the name.

static int nc_dn(X509_NAME *nm, X509_NAME *base) {

  // Ensure canonical encodings are up to date.

  if (nm->modified && i2d_X509_NAME(nm, NULL) < 0) {

    return X509_V_ERR_OUT_OF_MEM;

  }

  if (base->modified && i2d_X509_NAME(base, NULL) < 0) {

    return X509_V_ERR_OUT_OF_MEM;

  }

  if (base->canon_enclen > nm->canon_enclen) {

    return X509_V_ERR_PERMITTED_VIOLATION;

  }

  if (OPENSSL_memcmp(base->canon_enc, nm->canon_enc, base->canon_enclen)) {

    return X509_V_ERR_PERMITTED_VIOLATION;

  }

  return X509_V_OK;

}

static int starts_with(const CBS *cbs, uint8_t c) {

  return CBS_len(cbs) > 0 && CBS_data(cbs)[0] == c;

}

static int equal_case(const CBS *a, const CBS *b) {

  if (CBS_len(a) != CBS_len(b)) {

    return 0;

  }

  // Note we cannot use |OPENSSL_strncasecmp| because that would stop

  // iterating at NUL.

  const uint8_t *a_data = CBS_data(a), *b_data = CBS_data(b);

  for (size_t i = 0; i < CBS_len(a); i++) {

    if (OPENSSL_tolower(a_data[i]) != OPENSSL_tolower(b_data[i])) {

      return 0;

    }

  }

  return 1;

}

static int has_suffix_case(const CBS *a, const CBS *b) {

  if (CBS_len(a) < CBS_len(b)) {

    return 0;

  }

  CBS copy = *a;

  CBS_skip(&copy, CBS_len(a) - CBS_len(b));

  return equal_case(&copy, b);

}

static int nc_dns(const ASN1_IA5STRING *dns, const ASN1_IA5STRING *base) {

  CBS dns_cbs, base_cbs;

  CBS_init(&dns_cbs, dns->data, dns->length);

  CBS_init(&base_cbs, base->data, base->length);

  // Empty matches everything

  if (CBS_len(&base_cbs) == 0) {

    return X509_V_OK;

  }

  // If |base_cbs| begins with a '.', do a simple suffix comparison. This is

  // not part of RFC5280, but is part of OpenSSL's original behavior.

  if (starts_with(&base_cbs, '.')) {

    if (has_suffix_case(&dns_cbs, &base_cbs)) {

      return X509_V_OK;

    }

    return X509_V_ERR_PERMITTED_VIOLATION;

  }

  // Otherwise can add zero or more components on the left so compare RHS

  // and if dns is longer and expect '.' as preceding character.

  if (CBS_len(&dns_cbs) > CBS_len(&base_cbs)) {

    uint8_t dot;

    if (!CBS_skip(&dns_cbs, CBS_len(&dns_cbs) - CBS_len(&base_cbs) - 1) ||

        !CBS_get_u8(&dns_cbs, &dot) || dot != '.') {

      return X509_V_ERR_PERMITTED_VIOLATION;

    }

  }

  if (!equal_case(&dns_cbs, &base_cbs)) {

    return X509_V_ERR_PERMITTED_VIOLATION;

  }

  return X509_V_OK;

}

static int nc_email(const ASN1_IA5STRING *eml, const ASN1_IA5STRING *base) {

  CBS eml_cbs, base_cbs;

  CBS_init(&eml_cbs, eml->data, eml->length);

  CBS_init(&base_cbs, base->data, base->length);

  // TODO(davidben): In OpenSSL 1.1.1, this switched from the first '@' to the

  // last one. Match them here, or perhaps do an actual parse. Looks like

  // multiple '@'s may be allowed in quoted strings.

  CBS eml_local, base_local;

  if (!CBS_get_until_first(&eml_cbs, &eml_local, '@')) {

    return X509_V_ERR_UNSUPPORTED_NAME_SYNTAX;

  }

  int base_has_at = CBS_get_until_first(&base_cbs, &base_local, '@');

  // Special case: initial '.' is RHS match

  if (!base_has_at && starts_with(&base_cbs, '.')) {

    if (has_suffix_case(&eml_cbs, &base_cbs)) {

      return X509_V_OK;

    }

    return X509_V_ERR_PERMITTED_VIOLATION;

  }

  // If we have anything before '@' match local part

  if (base_has_at) {

    // TODO(davidben): This interprets a constraint of "@example.com" as

    // "example.com", which is not part of RFC5280.

    if (CBS_len(&base_local) > 0) {

      // Case sensitive match of local part

      if (!CBS_mem_equal(&base_local, CBS_data(&eml_local),

                         CBS_len(&eml_local))) {

        return X509_V_ERR_PERMITTED_VIOLATION;

      }

    }

    // Position base after '@'

    assert(starts_with(&base_cbs, '@'));

    CBS_skip(&base_cbs, 1);

  }

  // Just have hostname left to match: case insensitive

  assert(starts_with(&eml_cbs, '@'));

  CBS_skip(&eml_cbs, 1);

  if (!equal_case(&base_cbs, &eml_cbs)) {

    return X509_V_ERR_PERMITTED_VIOLATION;

  }

  return X509_V_OK;

}

static int nc_uri(const ASN1_IA5STRING *uri, const ASN1_IA5STRING *base) {

  CBS uri_cbs, base_cbs;

  CBS_init(&uri_cbs, uri->data, uri->length);

  CBS_init(&base_cbs, base->data, base->length);

  // Check for foo:// and skip past it

  CBS scheme;

  uint8_t byte;

  if (!CBS_get_until_first(&uri_cbs, &scheme, ':') ||

      !CBS_skip(&uri_cbs, 1) ||  // Skip the colon

      !CBS_get_u8(&uri_cbs, &byte) || byte != '/' ||

      !CBS_get_u8(&uri_cbs, &byte) || byte != '/') {

    return X509_V_ERR_UNSUPPORTED_NAME_SYNTAX;

  }

  // Look for a port indicator as end of hostname first. Otherwise look for

  // trailing slash, or the end of the string.

  // TODO(davidben): This is not a correct URI parser and mishandles IPv6

  // literals.

  CBS host;

  if (!CBS_get_until_first(&uri_cbs, &host, ':') &&

      !CBS_get_until_first(&uri_cbs, &host, '/')) {

    host = uri_cbs;

  }

  if (CBS_len(&host) == 0) {

    return X509_V_ERR_UNSUPPORTED_NAME_SYNTAX;

  }

  // Special case: initial '.' is RHS match

  if (starts_with(&base_cbs, '.')) {

    if (has_suffix_case(&host, &base_cbs)) {

      return X509_V_OK;

    }

    return X509_V_ERR_PERMITTED_VIOLATION;

  }

  if (!equal_case(&base_cbs, &host)) {

    return X509_V_ERR_PERMITTED_VIOLATION;

  }

  return X509_V_OK;

}