2 * Copyright 2004-2021 The OpenSSL Project Authors. All Rights Reserved.
4 * Licensed under the Apache License 2.0 (the "License"). You may not use
5 * this file except in compliance with the License. You can obtain a copy
6 * in the file LICENSE in the source distribution or at
7 * https://www.openssl.org/source/license.html
10 #include "internal/cryptlib.h"
11 #include <openssl/trace.h>
12 #include <openssl/x509.h>
13 #include <openssl/x509v3.h>
15 #include "pcy_local.h"
18 * If the maximum number of nodes in the policy tree isn't defined, set it to
19 * a generous default of 1000 nodes.
21 * Defining this to be zero means unlimited policy tree growth which opens the
22 * door on CVE-2023-0464.
24 #ifndef OPENSSL_POLICY_TREE_NODES_MAX
25 # define OPENSSL_POLICY_TREE_NODES_MAX 1000
28 static void expected_print(BIO *channel,
29 X509_POLICY_LEVEL *lev, X509_POLICY_NODE *node,
32 if ((lev->flags & X509_V_FLAG_INHIBIT_MAP)
33 || !(node->data->flags & POLICY_DATA_FLAG_MAP_MASK))
34 BIO_puts(channel, " Not Mapped\n");
38 STACK_OF(ASN1_OBJECT) *pset = node->data->expected_policy_set;
40 BIO_puts(channel, " Expected: ");
41 for (i = 0; i < sk_ASN1_OBJECT_num(pset); i++) {
42 oid = sk_ASN1_OBJECT_value(pset, i);
44 BIO_puts(channel, ", ");
45 i2a_ASN1_OBJECT(channel, oid);
47 BIO_puts(channel, "\n");
51 static void tree_print(BIO *channel,
52 char *str, X509_POLICY_TREE *tree,
53 X509_POLICY_LEVEL *curr)
55 X509_POLICY_LEVEL *plev;
58 curr = tree->levels + tree->nlevel;
62 BIO_printf(channel, "Level print after %s\n", str);
63 BIO_printf(channel, "Printing Up to Level %ld\n",
64 (long)(curr - tree->levels));
65 for (plev = tree->levels; plev != curr; plev++) {
68 BIO_printf(channel, "Level %ld, flags = %x\n",
69 (long)(plev - tree->levels), plev->flags);
70 for (i = 0; i < sk_X509_POLICY_NODE_num(plev->nodes); i++) {
71 X509_POLICY_NODE *node =
72 sk_X509_POLICY_NODE_value(plev->nodes, i);
74 X509_POLICY_NODE_print(channel, node, 2);
75 expected_print(channel, plev, node, 2);
76 BIO_printf(channel, " Flags: %x\n", node->data->flags);
79 X509_POLICY_NODE_print(channel, plev->anyPolicy, 2);
83 #define TREE_PRINT(str, tree, curr) \
84 OSSL_TRACE_BEGIN(X509V3_POLICY) { \
85 tree_print(trc_out, "before tree_prune()", tree, curr); \
86 } OSSL_TRACE_END(X509V3_POLICY)
89 * Return value: <= 0 on error, or positive bit mask:
91 * X509_PCY_TREE_VALID: valid tree
92 * X509_PCY_TREE_EMPTY: empty tree (including bare TA case)
93 * X509_PCY_TREE_EXPLICIT: explicit policy required
95 static int tree_init(X509_POLICY_TREE **ptree, STACK_OF(X509) *certs,
98 X509_POLICY_TREE *tree;
99 X509_POLICY_LEVEL *level;
100 const X509_POLICY_CACHE *cache;
101 X509_POLICY_DATA *data = NULL;
102 int ret = X509_PCY_TREE_VALID;
103 int n = sk_X509_num(certs) - 1; /* RFC5280 paths omit the TA */
104 int explicit_policy = (flags & X509_V_FLAG_EXPLICIT_POLICY) ? 0 : n+1;
105 int any_skip = (flags & X509_V_FLAG_INHIBIT_ANY) ? 0 : n+1;
106 int map_skip = (flags & X509_V_FLAG_INHIBIT_MAP) ? 0 : n+1;
111 /* Can't do anything with just a trust anchor */
113 return X509_PCY_TREE_EMPTY;
116 * First setup the policy cache in all n non-TA certificates, this will be
117 * used in X509_verify_cert() which will invoke the verify callback for all
118 * certificates with invalid policy extensions.
120 for (i = n - 1; i >= 0; i--) {
121 X509 *x = sk_X509_value(certs, i);
123 /* Call for side-effect of computing hash and caching extensions */
124 X509_check_purpose(x, -1, 0);
126 /* If cache is NULL, likely ENOMEM: return immediately */
127 if (ossl_policy_cache_set(x) == NULL)
128 return X509_PCY_TREE_INTERNAL;
132 * At this point check for invalid policies and required explicit policy.
133 * Note that the explicit_policy counter is a count-down to zero, with the
134 * requirement kicking in if and once it does that. The counter is
135 * decremented for every non-self-issued certificate in the path, but may
136 * be further reduced by policy constraints in a non-leaf certificate.
138 * The ultimate policy set is the intersection of all the policies along
139 * the path, if we hit a certificate with an empty policy set, and explicit
140 * policy is required we're done.
143 i >= 0 && (explicit_policy > 0 || (ret & X509_PCY_TREE_EMPTY) == 0);
145 X509 *x = sk_X509_value(certs, i);
146 uint32_t ex_flags = X509_get_extension_flags(x);
148 /* All the policies are already cached, we can return early */
149 if (ex_flags & EXFLAG_INVALID_POLICY)
150 return X509_PCY_TREE_INVALID;
152 /* Access the cache which we now know exists */
153 cache = ossl_policy_cache_set(x);
155 if ((ret & X509_PCY_TREE_VALID) && cache->data == NULL)
156 ret = X509_PCY_TREE_EMPTY;
157 if (explicit_policy > 0) {
158 if (!(ex_flags & EXFLAG_SI))
160 if ((cache->explicit_skip >= 0)
161 && (cache->explicit_skip < explicit_policy))
162 explicit_policy = cache->explicit_skip;
166 if (explicit_policy == 0)
167 ret |= X509_PCY_TREE_EXPLICIT;
168 if ((ret & X509_PCY_TREE_VALID) == 0)
171 /* If we get this far initialize the tree */
172 if ((tree = OPENSSL_zalloc(sizeof(*tree))) == NULL)
173 return X509_PCY_TREE_INTERNAL;
175 /* Limit the growth of the tree to mitigate CVE-2023-0464 */
176 tree->node_maximum = OPENSSL_POLICY_TREE_NODES_MAX;
179 * http://tools.ietf.org/html/rfc5280#section-6.1.2, figure 3.
181 * The top level is implicitly for the trust anchor with valid expected
182 * policies of anyPolicy. (RFC 5280 has the TA at depth 0 and the leaf at
183 * depth n, we have the leaf at depth 0 and the TA at depth n).
185 if ((tree->levels = OPENSSL_zalloc(sizeof(*tree->levels)*(n+1))) == NULL) {
187 return X509_PCY_TREE_INTERNAL;
190 level = tree->levels;
191 if ((data = ossl_policy_data_new(NULL,
192 OBJ_nid2obj(NID_any_policy), 0)) == NULL)
194 if (ossl_policy_level_add_node(level, data, NULL, tree, 1) == NULL) {
195 ossl_policy_data_free(data);
200 * In this pass initialize all the tree levels and whether anyPolicy and
201 * policy mapping are inhibited at each level.
203 for (i = n - 1; i >= 0; i--) {
204 X509 *x = sk_X509_value(certs, i);
205 uint32_t ex_flags = X509_get_extension_flags(x);
207 /* Access the cache which we now know exists */
208 cache = ossl_policy_cache_set(x);
213 if (!cache->anyPolicy)
214 level->flags |= X509_V_FLAG_INHIBIT_ANY;
216 /* Determine inhibit any and inhibit map flags */
219 * Any matching allowed only if certificate is self issued and not
220 * the last in the chain.
222 if (!(ex_flags & EXFLAG_SI) || (i == 0))
223 level->flags |= X509_V_FLAG_INHIBIT_ANY;
225 if (!(ex_flags & EXFLAG_SI))
227 if ((cache->any_skip >= 0) && (cache->any_skip < any_skip))
228 any_skip = cache->any_skip;
232 level->flags |= X509_V_FLAG_INHIBIT_MAP;
234 if (!(ex_flags & EXFLAG_SI))
236 if ((cache->map_skip >= 0) && (cache->map_skip < map_skip))
237 map_skip = cache->map_skip;
245 X509_policy_tree_free(tree);
246 return X509_PCY_TREE_INTERNAL;
250 * Return value: 1 on success, 0 otherwise
252 static int tree_link_matching_nodes(X509_POLICY_LEVEL *curr,
253 X509_POLICY_DATA *data,
254 X509_POLICY_TREE *tree)
256 X509_POLICY_LEVEL *last = curr - 1;
259 /* Iterate through all in nodes linking matches */
260 for (i = 0; i < sk_X509_POLICY_NODE_num(last->nodes); i++) {
261 X509_POLICY_NODE *node = sk_X509_POLICY_NODE_value(last->nodes, i);
263 if (ossl_policy_node_match(last, node, data->valid_policy)) {
264 if (ossl_policy_level_add_node(curr, data, node, tree, 0) == NULL)
269 if (!matched && last->anyPolicy) {
270 if (ossl_policy_level_add_node(curr, data, last->anyPolicy, tree, 0) == NULL)
277 * This corresponds to RFC3280 6.1.3(d)(1): link any data from
278 * CertificatePolicies onto matching parent or anyPolicy if no match.
280 * Return value: 1 on success, 0 otherwise.
282 static int tree_link_nodes(X509_POLICY_LEVEL *curr,
283 const X509_POLICY_CACHE *cache,
284 X509_POLICY_TREE *tree)
288 for (i = 0; i < sk_X509_POLICY_DATA_num(cache->data); i++) {
289 X509_POLICY_DATA *data = sk_X509_POLICY_DATA_value(cache->data, i);
291 /* Look for matching nodes in previous level */
292 if (!tree_link_matching_nodes(curr, data, tree))
299 * This corresponds to RFC3280 6.1.3(d)(2): Create new data for any unmatched
300 * policies in the parent and link to anyPolicy.
302 * Return value: 1 on success, 0 otherwise.
304 static int tree_add_unmatched(X509_POLICY_LEVEL *curr,
305 const X509_POLICY_CACHE *cache,
306 const ASN1_OBJECT *id,
307 X509_POLICY_NODE *node, X509_POLICY_TREE *tree)
309 X509_POLICY_DATA *data;
312 id = node->data->valid_policy;
314 * Create a new node with qualifiers from anyPolicy and id from unmatched
317 if ((data = ossl_policy_data_new(NULL, id, node_critical(node))) == NULL)
320 /* Curr may not have anyPolicy */
321 data->qualifier_set = cache->anyPolicy->qualifier_set;
322 data->flags |= POLICY_DATA_FLAG_SHARED_QUALIFIERS;
323 if (ossl_policy_level_add_node(curr, data, node, tree, 1) == NULL) {
324 ossl_policy_data_free(data);
331 * Return value: 1 on success, 0 otherwise.
333 static int tree_link_unmatched(X509_POLICY_LEVEL *curr,
334 const X509_POLICY_CACHE *cache,
335 X509_POLICY_NODE *node, X509_POLICY_TREE *tree)
337 const X509_POLICY_LEVEL *last = curr - 1;
340 if ((last->flags & X509_V_FLAG_INHIBIT_MAP)
341 || !(node->data->flags & POLICY_DATA_FLAG_MAPPED)) {
342 /* If no policy mapping: matched if one child present */
345 if (!tree_add_unmatched(curr, cache, NULL, node, tree))
349 /* If mapping: matched if one child per expected policy set */
350 STACK_OF(ASN1_OBJECT) *expset = node->data->expected_policy_set;
351 if (node->nchild == sk_ASN1_OBJECT_num(expset))
353 /* Locate unmatched nodes */
354 for (i = 0; i < sk_ASN1_OBJECT_num(expset); i++) {
355 ASN1_OBJECT *oid = sk_ASN1_OBJECT_value(expset, i);
356 if (ossl_policy_level_find_node(curr, node, oid))
358 if (!tree_add_unmatched(curr, cache, oid, node, tree))
367 * Return value: 1 on success, 0 otherwise
369 static int tree_link_any(X509_POLICY_LEVEL *curr,
370 const X509_POLICY_CACHE *cache,
371 X509_POLICY_TREE *tree)
374 X509_POLICY_NODE *node;
375 X509_POLICY_LEVEL *last = curr - 1;
377 for (i = 0; i < sk_X509_POLICY_NODE_num(last->nodes); i++) {
378 node = sk_X509_POLICY_NODE_value(last->nodes, i);
380 if (!tree_link_unmatched(curr, cache, node, tree))
383 /* Finally add link to anyPolicy */
384 if (last->anyPolicy &&
385 ossl_policy_level_add_node(curr, cache->anyPolicy,
386 last->anyPolicy, tree, 0) == NULL)
392 * Prune the tree: delete any child mapped child data on the current level then
393 * proceed up the tree deleting any data with no children. If we ever have no
394 * data on a level we can halt because the tree will be empty.
396 * Return value: <= 0 error, otherwise one of:
398 * X509_PCY_TREE_VALID: valid tree
399 * X509_PCY_TREE_EMPTY: empty tree
401 static int tree_prune(X509_POLICY_TREE *tree, X509_POLICY_LEVEL *curr)
403 STACK_OF(X509_POLICY_NODE) *nodes;
404 X509_POLICY_NODE *node;
407 if (curr->flags & X509_V_FLAG_INHIBIT_MAP) {
408 for (i = sk_X509_POLICY_NODE_num(nodes) - 1; i >= 0; i--) {
409 node = sk_X509_POLICY_NODE_value(nodes, i);
410 /* Delete any mapped data: see RFC3280 XXXX */
411 if (node->data->flags & POLICY_DATA_FLAG_MAP_MASK) {
412 node->parent->nchild--;
414 (void)sk_X509_POLICY_NODE_delete(nodes, i);
422 for (i = sk_X509_POLICY_NODE_num(nodes) - 1; i >= 0; i--) {
423 node = sk_X509_POLICY_NODE_value(nodes, i);
424 if (node->nchild == 0) {
425 node->parent->nchild--;
427 (void)sk_X509_POLICY_NODE_delete(nodes, i);
430 if (curr->anyPolicy && !curr->anyPolicy->nchild) {
431 if (curr->anyPolicy->parent)
432 curr->anyPolicy->parent->nchild--;
433 OPENSSL_free(curr->anyPolicy);
434 curr->anyPolicy = NULL;
436 if (curr == tree->levels) {
437 /* If we zapped anyPolicy at top then tree is empty */
438 if (!curr->anyPolicy)
439 return X509_PCY_TREE_EMPTY;
443 return X509_PCY_TREE_VALID;
447 * Return value: 1 on success, 0 otherwise.
449 static int tree_add_auth_node(STACK_OF(X509_POLICY_NODE) **pnodes,
450 X509_POLICY_NODE *pcy)
452 if (*pnodes == NULL &&
453 (*pnodes = ossl_policy_node_cmp_new()) == NULL)
455 if (sk_X509_POLICY_NODE_find(*pnodes, pcy) >= 0)
457 return sk_X509_POLICY_NODE_push(*pnodes, pcy) != 0;
460 #define TREE_CALC_FAILURE 0
461 #define TREE_CALC_OK_NOFREE 1
462 #define TREE_CALC_OK_DOFREE 2
465 * Calculate the authority set based on policy tree. The 'pnodes' parameter is
466 * used as a store for the set of policy nodes used to calculate the user set.
467 * If the authority set is not anyPolicy then pnodes will just point to the
468 * authority set. If however the authority set is anyPolicy then the set of
469 * valid policies (other than anyPolicy) is store in pnodes.
472 * TREE_CALC_FAILURE on failure,
473 * TREE_CALC_OK_NOFREE on success and pnodes need not be freed,
474 * TREE_CALC_OK_DOFREE on success and pnodes needs to be freed
476 static int tree_calculate_authority_set(X509_POLICY_TREE *tree,
477 STACK_OF(X509_POLICY_NODE) **pnodes)
479 X509_POLICY_LEVEL *curr;
480 X509_POLICY_NODE *node, *anyptr;
481 STACK_OF(X509_POLICY_NODE) **addnodes;
483 curr = tree->levels + tree->nlevel - 1;
485 /* If last level contains anyPolicy set is anyPolicy */
486 if (curr->anyPolicy) {
487 if (!tree_add_auth_node(&tree->auth_policies, curr->anyPolicy))
488 return TREE_CALC_FAILURE;
491 /* Add policies to authority set */
492 addnodes = &tree->auth_policies;
495 for (i = 1; i < tree->nlevel; i++) {
497 * If no anyPolicy node on this level it can't appear on lower
498 * levels so end search.
500 if ((anyptr = curr->anyPolicy) == NULL)
503 for (j = 0; j < sk_X509_POLICY_NODE_num(curr->nodes); j++) {
504 node = sk_X509_POLICY_NODE_value(curr->nodes, j);
505 if ((node->parent == anyptr)
506 && !tree_add_auth_node(addnodes, node)) {
507 if (addnodes == pnodes) {
508 sk_X509_POLICY_NODE_free(*pnodes);
511 return TREE_CALC_FAILURE;
515 if (addnodes == pnodes)
516 return TREE_CALC_OK_DOFREE;
518 *pnodes = tree->auth_policies;
519 return TREE_CALC_OK_NOFREE;
523 * Return value: 1 on success, 0 otherwise.
525 static int tree_calculate_user_set(X509_POLICY_TREE *tree,
526 STACK_OF(ASN1_OBJECT) *policy_oids,
527 STACK_OF(X509_POLICY_NODE) *auth_nodes)
530 X509_POLICY_NODE *node;
532 X509_POLICY_NODE *anyPolicy;
533 X509_POLICY_DATA *extra;
536 * Check if anyPolicy present in authority constrained policy set: this
537 * will happen if it is a leaf node.
539 if (sk_ASN1_OBJECT_num(policy_oids) <= 0)
542 anyPolicy = tree->levels[tree->nlevel - 1].anyPolicy;
544 for (i = 0; i < sk_ASN1_OBJECT_num(policy_oids); i++) {
545 oid = sk_ASN1_OBJECT_value(policy_oids, i);
546 if (OBJ_obj2nid(oid) == NID_any_policy) {
547 tree->flags |= POLICY_FLAG_ANY_POLICY;
552 for (i = 0; i < sk_ASN1_OBJECT_num(policy_oids); i++) {
553 oid = sk_ASN1_OBJECT_value(policy_oids, i);
554 node = ossl_policy_tree_find_sk(auth_nodes, oid);
559 * Create a new node with policy ID from user set and qualifiers
562 extra = ossl_policy_data_new(NULL, oid, node_critical(anyPolicy));
565 extra->qualifier_set = anyPolicy->data->qualifier_set;
566 extra->flags = POLICY_DATA_FLAG_SHARED_QUALIFIERS
567 | POLICY_DATA_FLAG_EXTRA_NODE;
568 node = ossl_policy_level_add_node(NULL, extra, anyPolicy->parent,
571 if (!tree->user_policies) {
572 tree->user_policies = sk_X509_POLICY_NODE_new_null();
573 if (!tree->user_policies)
576 if (!sk_X509_POLICY_NODE_push(tree->user_policies, node))
583 * Return value: <= 0 error, otherwise one of:
584 * X509_PCY_TREE_VALID: valid tree
585 * X509_PCY_TREE_EMPTY: empty tree
586 * (see tree_prune()).
588 static int tree_evaluate(X509_POLICY_TREE *tree)
591 X509_POLICY_LEVEL *curr = tree->levels + 1;
592 const X509_POLICY_CACHE *cache;
594 for (i = 1; i < tree->nlevel; i++, curr++) {
595 cache = ossl_policy_cache_set(curr->cert);
596 if (!tree_link_nodes(curr, cache, tree))
597 return X509_PCY_TREE_INTERNAL;
599 if (!(curr->flags & X509_V_FLAG_INHIBIT_ANY)
600 && !tree_link_any(curr, cache, tree))
601 return X509_PCY_TREE_INTERNAL;
602 TREE_PRINT("before tree_prune()", tree, curr);
603 ret = tree_prune(tree, curr);
604 if (ret != X509_PCY_TREE_VALID)
607 return X509_PCY_TREE_VALID;
610 static void exnode_free(X509_POLICY_NODE *node)
612 if (node->data && (node->data->flags & POLICY_DATA_FLAG_EXTRA_NODE))
616 void X509_policy_tree_free(X509_POLICY_TREE *tree)
618 X509_POLICY_LEVEL *curr;
624 sk_X509_POLICY_NODE_free(tree->auth_policies);
625 sk_X509_POLICY_NODE_pop_free(tree->user_policies, exnode_free);
627 for (i = 0, curr = tree->levels; i < tree->nlevel; i++, curr++) {
628 X509_free(curr->cert);
629 sk_X509_POLICY_NODE_pop_free(curr->nodes, ossl_policy_node_free);
630 ossl_policy_node_free(curr->anyPolicy);
633 sk_X509_POLICY_DATA_pop_free(tree->extra_data, ossl_policy_data_free);
634 OPENSSL_free(tree->levels);
640 * Application policy checking function.
642 * X509_PCY_TREE_FAILURE: Failure to satisfy explicit policy
643 * X509_PCY_TREE_INVALID: Inconsistent or invalid extensions
644 * X509_PCY_TREE_INTERNAL: Internal error, most likely malloc
645 * X509_PCY_TREE_VALID: Success (null tree if empty or bare TA)
647 int X509_policy_check(X509_POLICY_TREE **ptree, int *pexplicit_policy,
648 STACK_OF(X509) *certs,
649 STACK_OF(ASN1_OBJECT) *policy_oids, unsigned int flags)
654 X509_POLICY_TREE *tree = NULL;
655 STACK_OF(X509_POLICY_NODE) *nodes, *auth_nodes = NULL;
658 *pexplicit_policy = 0;
659 init_ret = tree_init(&tree, certs, flags);
664 if ((init_ret & X509_PCY_TREE_EXPLICIT) == 0) {
665 if (init_ret & X509_PCY_TREE_EMPTY) {
666 X509_policy_tree_free(tree);
667 return X509_PCY_TREE_VALID;
670 *pexplicit_policy = 1;
671 /* Tree empty and requireExplicit True: Error */
672 if (init_ret & X509_PCY_TREE_EMPTY)
673 return X509_PCY_TREE_FAILURE;
676 ret = tree_evaluate(tree);
677 TREE_PRINT("tree_evaluate()", tree, NULL);
681 if (ret == X509_PCY_TREE_EMPTY) {
682 X509_policy_tree_free(tree);
683 if (init_ret & X509_PCY_TREE_EXPLICIT)
684 return X509_PCY_TREE_FAILURE;
685 return X509_PCY_TREE_VALID;
688 /* Tree is not empty: continue */
690 if ((calc_ret = tree_calculate_authority_set(tree, &auth_nodes)) == 0)
692 sk_X509_POLICY_NODE_sort(auth_nodes);
693 ret = tree_calculate_user_set(tree, policy_oids, auth_nodes);
694 if (calc_ret == TREE_CALC_OK_DOFREE)
695 sk_X509_POLICY_NODE_free(auth_nodes);
701 if (init_ret & X509_PCY_TREE_EXPLICIT) {
702 nodes = X509_policy_tree_get0_user_policies(tree);
703 if (sk_X509_POLICY_NODE_num(nodes) <= 0)
704 return X509_PCY_TREE_FAILURE;
706 return X509_PCY_TREE_VALID;
709 X509_policy_tree_free(tree);
710 return X509_PCY_TREE_INTERNAL;