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pcy_tree.c

/* pcy_tree.c */
/* Written by Dr Stephen N Henson (shenson@bigfoot.com) for the OpenSSL
 * project 2004.
 */
/* ====================================================================
 * Copyright (c) 2004 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 "cryptlib.h"
#include <openssl/x509.h>
#include <openssl/x509v3.h>

#include "pcy_int.h"

/* Initialize policy tree. Return values:
 *  0 Some internal error occured.
 * -1 Inconsistent or invalid extensions in certificates.
 *  1 Tree initialized OK.
 *  2 Policy tree is empty.
 *  5 Tree OK and requireExplicitPolicy true.
 *  6 Tree empty and requireExplicitPolicy true.
 */

static int tree_init(X509_POLICY_TREE **ptree, STACK_OF(X509) *certs,
                  unsigned int flags)
      {
      X509_POLICY_TREE *tree;
      X509_POLICY_LEVEL *level;
      const X509_POLICY_CACHE *cache;
      X509_POLICY_DATA *data = NULL;
      X509 *x;
      int ret = 1;
      int i, n;
      int explicit_policy;
      int any_skip;
      int map_skip;
      *ptree = NULL;
      n = sk_X509_num(certs);

      /* Disable policy mapping for now... */
      flags |= X509_V_FLAG_INHIBIT_MAP;

      if (flags & X509_V_FLAG_EXPLICIT_POLICY)
            explicit_policy = 0;
      else
            explicit_policy = n + 1;

      if (flags & X509_V_FLAG_INHIBIT_ANY)
            any_skip = 0;
      else
            any_skip = n + 1;

      if (flags & X509_V_FLAG_INHIBIT_MAP)
            map_skip = 0;
      else
            map_skip = n + 1;

      /* Can't do anything with just a trust anchor */
      if (n == 1)
            return 1;
      /* First setup policy cache in all certificates apart from the
       * trust anchor. Note any bad cache results on the way. Also can
       * calculate explicit_policy value at this point.
       */
      for (i = n - 2; i >= 0; i--)
            {
            x = sk_X509_value(certs, i);
            X509_check_purpose(x, -1, -1);
            cache = policy_cache_set(x);
            /* If cache NULL something bad happened: return immediately */
            if (cache == NULL)
                  return 0;
            /* If inconsistent extensions keep a note of it but continue */
            if (x->ex_flags & EXFLAG_INVALID_POLICY)
                  ret = -1;
            /* Otherwise if we have no data (hence no CertificatePolicies)
             * and haven't already set an inconsistent code note it.
             */
            else if ((ret == 1) && !cache->data)
                  ret = 2;
            if (explicit_policy > 0)
                  {
                  explicit_policy--;
                  if (!(x->ex_flags & EXFLAG_SS)
                        && (cache->explicit_skip != -1)
                        && (cache->explicit_skip < explicit_policy))
                        explicit_policy = cache->explicit_skip;
                  }
            }

      if (ret != 1)
            {
            if (ret == 2 && !explicit_policy)
                  return 6;
            return ret;
            }


      /* If we get this far initialize the tree */

      tree = OPENSSL_malloc(sizeof(X509_POLICY_TREE));

      if (!tree)
            return 0;

      tree->flags = 0;
      tree->levels = OPENSSL_malloc(sizeof(X509_POLICY_LEVEL) * n);
      tree->nlevel = 0;
      tree->extra_data = NULL;
      tree->auth_policies = NULL;
      tree->user_policies = NULL;

      if (!tree)
            {
            OPENSSL_free(tree);
            return 0;
            }

      memset(tree->levels, 0, n * sizeof(X509_POLICY_LEVEL));

      tree->nlevel = n;

      level = tree->levels;

      /* Root data: initialize to anyPolicy */

      data = policy_data_new(NULL, OBJ_nid2obj(NID_any_policy), 0);

      if (!data || !level_add_node(level, data, NULL, tree))
            goto bad_tree;

      for (i = n - 2; i >= 0; i--)
            {
            level++;
            x = sk_X509_value(certs, i);
            cache = policy_cache_set(x);

            CRYPTO_add(&x->references, 1, CRYPTO_LOCK_X509);
            level->cert = x;

            if (!cache->anyPolicy)
                        level->flags |= X509_V_FLAG_INHIBIT_ANY;

            /* Determine inhibit any and inhibit map flags */
            if (any_skip == 0)
                  {
                  /* Any matching allowed if certificate is self
                   * issued and not the last in the chain.
                   */
                  if (!(x->ex_flags & EXFLAG_SS) || (i == 0))
                        level->flags |= X509_V_FLAG_INHIBIT_ANY;
                  }
            else
                  {
                  any_skip--;
                  if ((cache->any_skip > 0)
                        && (cache->any_skip < any_skip))
                        any_skip = cache->any_skip;
                  }

            if (map_skip == 0)
                  level->flags |= X509_V_FLAG_INHIBIT_MAP;
            else
                  {
                  map_skip--;
                  if ((cache->map_skip > 0)
                        && (cache->map_skip < map_skip))
                        map_skip = cache->map_skip;
                  }


            }

      *ptree = tree;

      if (explicit_policy)
            return 1;
      else
            return 5;

      bad_tree:

      X509_policy_tree_free(tree);

      return 0;

      }

/* This corresponds to RFC3280 XXXX XXXXX:
 * link any data from CertificatePolicies onto matching parent
 * or anyPolicy if no match.
 */

static int tree_link_nodes(X509_POLICY_LEVEL *curr,
                        const X509_POLICY_CACHE *cache)
      {
      int i;
      X509_POLICY_LEVEL *last;
      X509_POLICY_DATA *data;
      X509_POLICY_NODE *parent;
      last = curr - 1;
      for (i = 0; i < sk_X509_POLICY_DATA_num(cache->data); i++)
            {
            data = sk_X509_POLICY_DATA_value(cache->data, i);
            /* If a node is mapped any it doesn't have a corresponding
             * CertificatePolicies entry. 
             * However such an identical node would be created
             * if anyPolicy matching is enabled because there would be
             * no match with the parent valid_policy_set. So we create
             * link because then it will have the mapping flags
             * right and we can prune it later.
             */
            if ((data->flags & POLICY_DATA_FLAG_MAPPED_ANY)
                  && !(curr->flags & X509_V_FLAG_INHIBIT_ANY))
                  continue;
            /* Look for matching node in parent */
            parent = level_find_node(last, data->valid_policy);
            /* If no match link to anyPolicy */
            if (!parent)
                  parent = last->anyPolicy;
            if (parent && !level_add_node(curr, data, parent, NULL))
                        return 0;
            }
      return 1;
      }

/* This corresponds to RFC3280 XXXX XXXXX:
 * Create new data for any unmatched policies in the parent and link
 * to anyPolicy.
 */

static int tree_link_any(X509_POLICY_LEVEL *curr,
                  const X509_POLICY_CACHE *cache,
                  X509_POLICY_TREE *tree)
      {
      int i;
      X509_POLICY_DATA *data;
      X509_POLICY_NODE *node;
      X509_POLICY_LEVEL *last;

      last = curr - 1;

      for (i = 0; i < sk_X509_POLICY_NODE_num(last->nodes); i++)
            {
            node = sk_X509_POLICY_NODE_value(last->nodes, i);

            /* Skip any node with any children: we only want unmathced
             * nodes.
             *
             * Note: need something better for policy mapping
             * because each node may have multiple children 
             */
            if (node->nchild)
                  continue;
            /* Create a new node with qualifiers from anyPolicy and
             * id from unmatched node.
             */
            data = policy_data_new(NULL, node->data->valid_policy, 
                                    node_critical(node));

            if (data == NULL)
                  return 0;
            data->qualifier_set = curr->anyPolicy->data->qualifier_set;
            data->flags |= POLICY_DATA_FLAG_SHARED_QUALIFIERS;
            if (!level_add_node(curr, data, node, tree))
                  {
                  policy_data_free(data);
                  return 0;
                  }
            }
      /* Finally add link to anyPolicy */
      if (last->anyPolicy)
            {
            if (!level_add_node(curr, cache->anyPolicy,
                                    last->anyPolicy, NULL))
                  return 0;
            }
      return 1;
      }

/* Prune the tree: delete any child mapped child data on the current level
 * then proceed up the tree deleting any data with no children. If we ever
 * have no data on a level we can halt because the tree will be empty.
 */

static int tree_prune(X509_POLICY_TREE *tree, X509_POLICY_LEVEL *curr)
      {
      X509_POLICY_NODE *node;
      int i;
      for (i = sk_X509_POLICY_NODE_num(curr->nodes) - 1; i >= 0; i--)
            {
            node = sk_X509_POLICY_NODE_value(curr->nodes, i);
            /* Delete any mapped data: see RFC3280 XXXX */
            if (node->data->flags & POLICY_DATA_FLAG_MAP_MASK)
                  {
                  node->parent->nchild--;
                  OPENSSL_free(node);
                  sk_X509_POLICY_NODE_delete(curr->nodes, i);
                  }
            }

      for(;;)     {
            --curr;
            for (i = sk_X509_POLICY_NODE_num(curr->nodes) - 1; i >= 0; i--)
                  {
                  node = sk_X509_POLICY_NODE_value(curr->nodes, i);
                  if (node->nchild == 0)
                        {
                        node->parent->nchild--;
                        OPENSSL_free(node);
                        sk_X509_POLICY_NODE_delete(curr->nodes, i);
                        }
                  }
            if (curr->anyPolicy && !curr->anyPolicy->nchild)
                  {
                  if (curr->anyPolicy->parent)
                        curr->anyPolicy->parent->nchild--;
                  OPENSSL_free(curr->anyPolicy);
                  curr->anyPolicy = NULL;
                  }
            if (curr == tree->levels)
                  {
                  /* If we zapped anyPolicy at top then tree is empty */
                  if (!curr->anyPolicy)
                              return 2;
                  return 1;
                  }
            }

      return 1;

      }

static int tree_add_auth_node(STACK_OF(X509_POLICY_NODE) **pnodes,
                                     X509_POLICY_NODE *pcy)
      {
      if (!*pnodes)
            {
            *pnodes = policy_node_cmp_new();
            if (!*pnodes)
                  return 0;
            }
      else if (sk_X509_POLICY_NODE_find(*pnodes, pcy) != -1)
            return 1;

      if (!sk_X509_POLICY_NODE_push(*pnodes, pcy))
            return 0;

      return 1;

      }

/* Calculate the authority set based on policy tree.
 * The 'pnodes' parameter is used as a store for the set of policy nodes
 * used to calculate the user set. If the authority set is not anyPolicy
 * then pnodes will just point to the authority set. If however the authority
 * set is anyPolicy then the set of valid policies (other than anyPolicy)
 * is store in pnodes. The return value of '2' is used in this case to indicate
 * that pnodes should be freed.
 */

static int tree_calculate_authority_set(X509_POLICY_TREE *tree,
                              STACK_OF(X509_POLICY_NODE) **pnodes)
      {
      X509_POLICY_LEVEL *curr;
      X509_POLICY_NODE *node, *anyptr;
      STACK_OF(X509_POLICY_NODE) **addnodes;
      int i, j;
      curr = tree->levels + tree->nlevel - 1;

      /* If last level contains anyPolicy set is anyPolicy */
      if (curr->anyPolicy)
            {
            if (!tree_add_auth_node(&tree->auth_policies, curr->anyPolicy))
                  return 0;
            addnodes = pnodes;
            }
      else
            /* Add policies to authority set */
            addnodes = &tree->auth_policies;

      curr = tree->levels;
      for (i = 1; i < tree->nlevel; i++)
            {
            /* If no anyPolicy node on this this level it can't
             * appear on lower levels so end search.
             */
            if (!(anyptr = curr->anyPolicy))
                  break;
            curr++;
            for (j = 0; j < sk_X509_POLICY_NODE_num(curr->nodes); j++)
                  {
                  node = sk_X509_POLICY_NODE_value(curr->nodes, j);
                  if ((node->parent == anyptr)
                        && !tree_add_auth_node(addnodes, node))
                              return 0;
                  }
            }

      if (addnodes == pnodes)
            return 2;

      *pnodes = tree->auth_policies;

      return 1;
      }

static int tree_calculate_user_set(X509_POLICY_TREE *tree,
                        STACK_OF(ASN1_OBJECT) *policy_oids,
                        STACK_OF(X509_POLICY_NODE) *auth_nodes)
      {
      int i;
      X509_POLICY_NODE *node;
      ASN1_OBJECT *oid;

      X509_POLICY_NODE *anyPolicy;
      X509_POLICY_DATA *extra;

      /* Check if anyPolicy present in authority constrained policy set:
       * this will happen if it is a leaf node.
       */

      if (sk_ASN1_OBJECT_num(policy_oids) <= 0)
            return 1;

      anyPolicy = tree->levels[tree->nlevel - 1].anyPolicy;

      for (i = 0; i < sk_ASN1_OBJECT_num(policy_oids); i++)
            {
            oid = sk_ASN1_OBJECT_value(policy_oids, i);
            if (OBJ_obj2nid(oid) == NID_any_policy)
                  {
                  tree->flags |= POLICY_FLAG_ANY_POLICY;
                  return 1;
                  }
            }

      for (i = 0; i < sk_ASN1_OBJECT_num(policy_oids); i++)
            {
            oid = sk_ASN1_OBJECT_value(policy_oids, i);
            node = tree_find_sk(auth_nodes, oid);
            if (!node)
                  {
                  if (!anyPolicy)
                        continue;
                  /* Create a new node with policy ID from user set
                   * and qualifiers from anyPolicy.
                   */
                  extra = policy_data_new(NULL, oid,
                                    node_critical(anyPolicy));
                  if (!extra)
                        return 0;
                  extra->qualifier_set = anyPolicy->data->qualifier_set;
                  extra->flags = POLICY_DATA_FLAG_SHARED_QUALIFIERS
                                    | POLICY_DATA_FLAG_EXTRA_NODE;
                  node = level_add_node(NULL, extra, anyPolicy->parent,
                                    tree);
                  }
            if (!tree->user_policies)
                  {
                  tree->user_policies = sk_X509_POLICY_NODE_new_null();
                  if (!tree->user_policies)
                        return 1;
                  }
            if (!sk_X509_POLICY_NODE_push(tree->user_policies, node))
                  return 0;
            }
      return 1;

      }

static int tree_evaluate(X509_POLICY_TREE *tree)
      {
      int ret, i;
      X509_POLICY_LEVEL *curr = tree->levels + 1;
      const X509_POLICY_CACHE *cache;

      for(i = 1; i < tree->nlevel; i++, curr++)
            {
            cache = policy_cache_set(curr->cert);
            if (!tree_link_nodes(curr, cache))
                  return 0;

            if (!(curr->flags & X509_V_FLAG_INHIBIT_ANY)
                  && !tree_link_any(curr, cache, tree))
                  return 0;
            ret = tree_prune(tree, curr);
            if (ret != 1)
                  return ret;
            }

      return 1;

      }

static void exnode_free(X509_POLICY_NODE *node)
      {
      if (node->data && (node->data->flags & POLICY_DATA_FLAG_EXTRA_NODE))
            OPENSSL_free(node);
      }


void X509_policy_tree_free(X509_POLICY_TREE *tree)
      {
      X509_POLICY_LEVEL *curr;
      int i;

      if (!tree)
            return;

      sk_X509_POLICY_NODE_free(tree->auth_policies);
      sk_X509_POLICY_NODE_pop_free(tree->user_policies, exnode_free);

      for(i = 0, curr = tree->levels; i < tree->nlevel; i++, curr++)
            {
            if (curr->cert)
                  X509_free(curr->cert);
            if (curr->nodes)
                  sk_X509_POLICY_NODE_pop_free(curr->nodes,
                                    policy_node_free);
            if (curr->anyPolicy)
                  policy_node_free(curr->anyPolicy);
            }

      if (tree->extra_data)
            sk_X509_POLICY_DATA_pop_free(tree->extra_data,
                                    policy_data_free);

      OPENSSL_free(tree->levels);
      OPENSSL_free(tree);

      }

/* Application policy checking function.
 * Return codes:
 *  0       Internal Error.
 *  1   Successful.
 * -1   One or more certificates contain invalid or inconsistent extensions
 * -2 User constrained policy set empty and requireExplicit true.
 */

int X509_policy_check(X509_POLICY_TREE **ptree, int *pexplicit_policy,
                  STACK_OF(X509) *certs,
                  STACK_OF(ASN1_OBJECT) *policy_oids,
                  unsigned int flags)
      {
      int ret;
      X509_POLICY_TREE *tree = NULL;
      STACK_OF(X509_POLICY_NODE) *nodes, *auth_nodes = NULL;
      *ptree = NULL;

      *pexplicit_policy = 0;
      ret = tree_init(&tree, certs, flags);


      switch (ret)
            {

            /* Tree empty requireExplicit False: OK */
            case 2:
            return 1;

            /* Some internal error */
            case 0:
            return 0;

            /* Tree empty requireExplicit True: Error */

            case 6:
            *pexplicit_policy = 1;
            return -2;

            /* Tree OK requireExplicit True: OK and continue */
            case 5:
            *pexplicit_policy = 1;
            break;

            /* Tree OK: continue */

            case 1:
            break;
            }

      if (!tree) goto error;
      ret = tree_evaluate(tree);

      if (ret <= 0)
            goto error;

      /* Return value 2 means tree empty */
      if (ret == 2)
            {
            X509_policy_tree_free(tree);
            if (*pexplicit_policy)
                  return -2;
            else
                  return 1;
            }

      /* Tree is not empty: continue */

      ret = tree_calculate_authority_set(tree, &auth_nodes);

      if (!ret)
            goto error;

      if (!tree_calculate_user_set(tree, policy_oids, auth_nodes))
            goto error;
      
      if (ret == 2)
            sk_X509_POLICY_NODE_free(auth_nodes);

      if (tree)
            *ptree = tree;

      if (*pexplicit_policy)
            {
            nodes = X509_policy_tree_get0_user_policies(tree);
            if (sk_X509_POLICY_NODE_num(nodes) <= 0)
                  return -2;
            }

      return 1;

      error:

      X509_policy_tree_free(tree);

      return 0;

      }


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