/* $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;
}
