Collapse the x509v3 directory into x509.

This avoids the need to grep across directories to find functions and
prepares for further rototilling and chainsawing.

Discussed with tb@ (who also tested the release build)

1 files changed, 770 insertions, 0 deletions

diff --git a/src/lib/libcrypto/x509/pcy_tree.c b/src/lib/libcrypto/x509/pcy_tree.c
new file mode 100644
index 0000000000..d0f7cd1ada
--- /dev/null
+++ b/src/lib/libcrypto/x509/pcy_tree.c
@@ -0,0 +1,770 @@
+/* $OpenBSD: pcy_tree.c,v 1.1 2020/06/04 15:19:31 jsing Exp $ */
+/* Written by Dr Stephen N Henson (steve@openssl.org) 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 <openssl/x509.h>
+#include <openssl/x509v3.h>
+
+#include "pcy_int.h"
+
+/* Enable this to print out the complete policy tree at various point during
+ * evaluation.
+ */
+
+/*#define OPENSSL_POLICY_DEBUG*/
+
+#ifdef OPENSSL_POLICY_DEBUG
+
+static void
+expected_print(BIO *err, X509_POLICY_LEVEL *lev, X509_POLICY_NODE *node,
+    int indent)
+{
+        if ((lev->flags & X509_V_FLAG_INHIBIT_MAP) ||
+            !(node->data->flags & POLICY_DATA_FLAG_MAP_MASK))
+                BIO_puts(err, "  Not Mapped\n");
+        else {
+                int i;
+                STACK_OF(ASN1_OBJECT) *pset = node->data->expected_policy_set;
+                ASN1_OBJECT *oid;
+                BIO_puts(err, "  Expected: ");
+                for (i = 0; i < sk_ASN1_OBJECT_num(pset); i++) {
+                        oid = sk_ASN1_OBJECT_value(pset, i);
+                        if (i)
+                                BIO_puts(err, ", ");
+                        i2a_ASN1_OBJECT(err, oid);
+                }
+                BIO_puts(err, "\n");
+        }
+}
+
+static void
+tree_print(char *str, X509_POLICY_TREE *tree, X509_POLICY_LEVEL *curr)
+{
+        X509_POLICY_LEVEL *plev;
+        X509_POLICY_NODE *node;
+        int i;
+        BIO *err;
+
+        if ((err = BIO_new_fp(stderr, BIO_NOCLOSE)) == NULL)
+                return;
+
+        if (!curr)
+                curr = tree->levels + tree->nlevel;
+        else
+                curr++;
+        BIO_printf(err, "Level print after %s\n", str);
+        BIO_printf(err, "Printing Up to Level %ld\n", curr - tree->levels);
+        for (plev = tree->levels; plev != curr; plev++) {
+                BIO_printf(err, "Level %ld, flags = %x\n",
+                    plev - tree->levels, plev->flags);
+                for (i = 0; i < sk_X509_POLICY_NODE_num(plev->nodes); i++) {
+                        node = sk_X509_POLICY_NODE_value(plev->nodes, i);
+                        X509_POLICY_NODE_print(err, node, 2);
+                        expected_print(err, plev, node, 2);
+                        BIO_printf(err, "  Flags: %x\n", node->data->flags);
+                }
+                if (plev->anyPolicy)
+                        X509_POLICY_NODE_print(err, plev->anyPolicy, 2);
+        }
+
+        BIO_free(err);
+}
+#else
+
+#define tree_print(a,b,c) /* */
+
+#endif
+
+/* 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);
+
+        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) {
+                        if (!(x->ex_flags & EXFLAG_SI))
+                                explicit_policy--;
+                        if ((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 = malloc(sizeof(X509_POLICY_TREE));
+
+        if (!tree)
+                return 0;
+
+        tree->flags = 0;
+        tree->levels = calloc(n, sizeof(X509_POLICY_LEVEL));
+        tree->nlevel = 0;
+        tree->extra_data = NULL;
+        tree->auth_policies = NULL;
+        tree->user_policies = NULL;
+
+        if (!tree->levels) {
+                free(tree);
+                return 0;
+        }
+
+        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, NULL))
+                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_SI) || (i == 0))
+                                level->flags |= X509_V_FLAG_INHIBIT_ANY;
+                } else {
+                        if (!(x->ex_flags & EXFLAG_SI))
+                                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 {
+                        if (!(x->ex_flags & EXFLAG_SI))
+                                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;
+}
+
+static int
+tree_link_matching_nodes(X509_POLICY_LEVEL *curr, const X509_POLICY_DATA *data)
+{
+        X509_POLICY_LEVEL *last = curr - 1;
+        X509_POLICY_NODE *node;
+        int i, matched = 0;
+
+        /* Iterate through all in nodes linking matches */
+        for (i = 0; i < sk_X509_POLICY_NODE_num(last->nodes); i++) {
+                node = sk_X509_POLICY_NODE_value(last->nodes, i);
+                if (policy_node_match(last, node, data->valid_policy)) {
+                        if (!level_add_node(curr, data, node, NULL, NULL))
+                                return 0;
+                        matched = 1;
+                }
+        }
+        if (!matched && last->anyPolicy) {
+                if (!level_add_node(curr, data, last->anyPolicy, NULL, NULL))
+                        return 0;
+        }
+        return 1;
+}
+
+/* This corresponds to RFC3280 6.1.3(d)(1):
+ * 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_DATA *data;
+
+        for (i = 0; i < sk_X509_POLICY_DATA_num(cache->data); i++) {
+                data = sk_X509_POLICY_DATA_value(cache->data, i);
+                /* Look for matching nodes in previous level */
+                if (!tree_link_matching_nodes(curr, data))
+                        return 0;
+        }
+        return 1;
+}
+
+/* This corresponds to RFC3280 6.1.3(d)(2):
+ * Create new data for any unmatched policies in the parent and link
+ * to anyPolicy.
+ */
+
+static int
+tree_add_unmatched(X509_POLICY_LEVEL *curr, const X509_POLICY_CACHE *cache,
+    const ASN1_OBJECT *id, X509_POLICY_NODE *node, X509_POLICY_TREE *tree)
+{
+        X509_POLICY_DATA *data;
+
+        if (id == NULL)
+                id = node->data->valid_policy;
+        /* Create a new node with qualifiers from anyPolicy and
+         * id from unmatched node.
+         */
+        data = policy_data_new(NULL, id, node_critical(node));
+
+        if (data == NULL)
+                return 0;
+        /* Curr may not have anyPolicy */
+        data->qualifier_set = cache->anyPolicy->qualifier_set;
+        data->flags |= POLICY_DATA_FLAG_SHARED_QUALIFIERS;
+        if (!level_add_node(curr, data, node, tree, NULL)) {
+                policy_data_free(data);
+                return 0;
+        }
+
+        return 1;
+}
+
+static int
+tree_link_unmatched(X509_POLICY_LEVEL *curr, const X509_POLICY_CACHE *cache,
+    X509_POLICY_NODE *node, X509_POLICY_TREE *tree)
+{
+        const X509_POLICY_LEVEL *last = curr - 1;
+        int i;
+
+        if ((last->flags & X509_V_FLAG_INHIBIT_MAP) ||
+            !(node->data->flags & POLICY_DATA_FLAG_MAPPED)) {
+                /* If no policy mapping: matched if one child present */
+                if (node->nchild)
+                        return 1;
+                if (!tree_add_unmatched(curr, cache, NULL, node, tree))
+                        return 0;
+                /* Add it */
+        } else {
+                /* If mapping: matched if one child per expected policy set */
+                STACK_OF(ASN1_OBJECT) *expset = node->data->expected_policy_set;
+                if (node->nchild == sk_ASN1_OBJECT_num(expset))
+                        return 1;
+                /* Locate unmatched nodes */
+                for (i = 0; i < sk_ASN1_OBJECT_num(expset); i++) {
+                        ASN1_OBJECT *oid = sk_ASN1_OBJECT_value(expset, i);
+                        if (level_find_node(curr, node, oid))
+                                continue;
+                        if (!tree_add_unmatched(curr, cache, oid, node, tree))
+                                return 0;
+                }
+        }
+
+        return 1;
+}
+
+static int
+tree_link_any(X509_POLICY_LEVEL *curr, const X509_POLICY_CACHE *cache,
+    X509_POLICY_TREE *tree)
+{
+        int i;
+        X509_POLICY_NODE *node;
+        X509_POLICY_LEVEL *last = curr - 1;
+
+        for (i = 0; i < sk_X509_POLICY_NODE_num(last->nodes); i++) {
+                node = sk_X509_POLICY_NODE_value(last->nodes, i);
+
+                if (!tree_link_unmatched(curr, cache, node, tree))
+                        return 0;
+        }
+        /* Finally add link to anyPolicy */
+        if (last->anyPolicy) {
+                if (!level_add_node(curr, cache->anyPolicy,
+                    last->anyPolicy, NULL, 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)
+{
+        STACK_OF(X509_POLICY_NODE) *nodes;
+        X509_POLICY_NODE *node;
+        int i;
+
+        nodes = curr->nodes;
+        if (curr->flags & X509_V_FLAG_INHIBIT_MAP) {
+                for (i = sk_X509_POLICY_NODE_num(nodes) - 1; i >= 0; i--) {
+                        node = sk_X509_POLICY_NODE_value(nodes, i);
+                        /* Delete any mapped data: see RFC3280 XXXX */
+                        if (node->data->flags & POLICY_DATA_FLAG_MAP_MASK) {
+                                node->parent->nchild--;
+                                free(node);
+                                (void)sk_X509_POLICY_NODE_delete(nodes, i);
+                        }
+                }
+        }
+
+        for (;;) {
+                --curr;
+                nodes = curr->nodes;
+                for (i = sk_X509_POLICY_NODE_num(nodes) - 1; i >= 0; i--) {
+                        node = sk_X509_POLICY_NODE_value(nodes, i);
+                        if (node->nchild == 0) {
+                                node->parent->nchild--;
+                                free(node);
+                                (void)sk_X509_POLICY_NODE_delete(nodes, i);
+                        }
+                }
+                if (curr->anyPolicy && !curr->anyPolicy->nchild) {
+                        if (curr->anyPolicy->parent)
+                                curr->anyPolicy->parent->nchild--;
+                        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;
+                        (void) level_add_node(NULL, extra, anyPolicy->parent,
+                            tree, &node);
+                }
+                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;
+                tree_print("before tree_prune()", tree, curr);
+                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))
+                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++) {
+                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);
+
+        free(tree->levels);
+        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, ret2;
+        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 -1:
+                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:
+                if (!tree)
+                        /*
+                         * tree_init() returns success and a null tree
+                         * if it's just looking at a trust anchor.
+                         * I'm not sure that returning success here is
+                         * correct, but I'm sure that reporting this
+                         * as an internal error which our caller
+                         * interprets as a malloc failure is wrong.
+                         */
+                        return 1;
+                break;
+        }
+
+        if (!tree)
+                goto error;
+        ret = tree_evaluate(tree);
+
+        tree_print("tree_evaluate()", tree, NULL);
+
+        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 == 0)
+                goto error;
+
+        ret2 = tree_calculate_user_set(tree, policy_oids, auth_nodes);
+
+        /* Return value 2 means auth_nodes needs to be freed */
+        if (ret == 2)
+                sk_X509_POLICY_NODE_free(auth_nodes);
+
+        if (ret2 == 0)
+                goto error;
+
+        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;
+}