/* * Copyright 2004-2023 The OpenSSL Project Authors. All Rights Reserved. * * Licensed under the Apache License 2.0 (the "License"). You may not use * this file except in compliance with the License. You can obtain a copy * in the file LICENSE in the source distribution or at * https://www.openssl.org/source/license.html */ #include "internal/cryptlib.h" #include #include #include #include "pcy_local.h" /* * If the maximum number of nodes in the policy tree isn't defined, set it to * a generous default of 1000 nodes. * * Defining this to be zero means unlimited policy tree growth which opens the * door on CVE-2023-0464. */ #ifndef OPENSSL_POLICY_TREE_NODES_MAX # define OPENSSL_POLICY_TREE_NODES_MAX 1000 #endif static void exnode_free(X509_POLICY_NODE *node); static void expected_print(BIO *channel, 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(channel, " Not Mapped\n"); else { int i; STACK_OF(ASN1_OBJECT) *pset = node->data->expected_policy_set; ASN1_OBJECT *oid; BIO_puts(channel, " Expected: "); for (i = 0; i < sk_ASN1_OBJECT_num(pset); i++) { oid = sk_ASN1_OBJECT_value(pset, i); if (i) BIO_puts(channel, ", "); i2a_ASN1_OBJECT(channel, oid); } BIO_puts(channel, "\n"); } } static void tree_print(BIO *channel, char *str, X509_POLICY_TREE *tree, X509_POLICY_LEVEL *curr) { X509_POLICY_LEVEL *plev; if (!curr) curr = tree->levels + tree->nlevel; else curr++; BIO_printf(channel, "Level print after %s\n", str); BIO_printf(channel, "Printing Up to Level %ld\n", (long)(curr - tree->levels)); for (plev = tree->levels; plev != curr; plev++) { int i; BIO_printf(channel, "Level %ld, flags = %x\n", (long)(plev - tree->levels), plev->flags); for (i = 0; i < sk_X509_POLICY_NODE_num(plev->nodes); i++) { X509_POLICY_NODE *node = sk_X509_POLICY_NODE_value(plev->nodes, i); X509_POLICY_NODE_print(channel, node, 2); expected_print(channel, plev, node, 2); BIO_printf(channel, " Flags: %x\n", node->data->flags); } if (plev->anyPolicy) X509_POLICY_NODE_print(channel, plev->anyPolicy, 2); } } #define TREE_PRINT(str, tree, curr) \ OSSL_TRACE_BEGIN(X509V3_POLICY) { \ tree_print(trc_out, "before tree_prune()", tree, curr); \ } OSSL_TRACE_END(X509V3_POLICY) /*- * Return value: <= 0 on error, or positive bit mask: * * X509_PCY_TREE_VALID: valid tree * X509_PCY_TREE_EMPTY: empty tree (including bare TA case) * X509_PCY_TREE_EXPLICIT: explicit policy required */ 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; int ret = X509_PCY_TREE_VALID; int n = sk_X509_num(certs) - 1; /* RFC5280 paths omit the TA */ int explicit_policy = (flags & X509_V_FLAG_EXPLICIT_POLICY) ? 0 : n+1; int any_skip = (flags & X509_V_FLAG_INHIBIT_ANY) ? 0 : n+1; int map_skip = (flags & X509_V_FLAG_INHIBIT_MAP) ? 0 : n+1; int i; *ptree = NULL; /* Can't do anything with just a trust anchor */ if (n == 0) return X509_PCY_TREE_EMPTY; /* * First setup the policy cache in all n non-TA certificates, this will be * used in X509_verify_cert() which will invoke the verify callback for all * certificates with invalid policy extensions. */ for (i = n - 1; i >= 0; i--) { X509 *x = sk_X509_value(certs, i); /* Call for side-effect of computing hash and caching extensions */ X509_check_purpose(x, -1, 0); /* If cache is NULL, likely ENOMEM: return immediately */ if (ossl_policy_cache_set(x) == NULL) return X509_PCY_TREE_INTERNAL; } /* * At this point check for invalid policies and required explicit policy. * Note that the explicit_policy counter is a count-down to zero, with the * requirement kicking in if and once it does that. The counter is * decremented for every non-self-issued certificate in the path, but may * be further reduced by policy constraints in a non-leaf certificate. * * The ultimate policy set is the intersection of all the policies along * the path, if we hit a certificate with an empty policy set, and explicit * policy is required we're done. */ for (i = n - 1; i >= 0 && (explicit_policy > 0 || (ret & X509_PCY_TREE_EMPTY) == 0); i--) { X509 *x = sk_X509_value(certs, i); uint32_t ex_flags = X509_get_extension_flags(x); /* All the policies are already cached, we can return early */ if (ex_flags & EXFLAG_INVALID_POLICY) return X509_PCY_TREE_INVALID; /* Access the cache which we now know exists */ cache = ossl_policy_cache_set(x); if ((ret & X509_PCY_TREE_VALID) && cache->data == NULL) ret = X509_PCY_TREE_EMPTY; if (explicit_policy > 0) { if (!(ex_flags & EXFLAG_SI)) explicit_policy--; if ((cache->explicit_skip >= 0) && (cache->explicit_skip < explicit_policy)) explicit_policy = cache->explicit_skip; } } if (explicit_policy == 0) ret |= X509_PCY_TREE_EXPLICIT; if ((ret & X509_PCY_TREE_VALID) == 0) return ret; /* If we get this far initialize the tree */ if ((tree = OPENSSL_zalloc(sizeof(*tree))) == NULL) return X509_PCY_TREE_INTERNAL; /* Limit the growth of the tree to mitigate CVE-2023-0464 */ tree->node_maximum = OPENSSL_POLICY_TREE_NODES_MAX; /* * http://tools.ietf.org/html/rfc5280#section-6.1.2, figure 3. * * The top level is implicitly for the trust anchor with valid expected * policies of anyPolicy. (RFC 5280 has the TA at depth 0 and the leaf at * depth n, we have the leaf at depth 0 and the TA at depth n). */ if ((tree->levels = OPENSSL_zalloc(sizeof(*tree->levels)*(n+1))) == NULL) { OPENSSL_free(tree); return X509_PCY_TREE_INTERNAL; } tree->nlevel = n+1; level = tree->levels; if ((data = ossl_policy_data_new(NULL, OBJ_nid2obj(NID_any_policy), 0)) == NULL) goto bad_tree; if (ossl_policy_level_add_node(level, data, NULL, tree, 1) == NULL) { ossl_policy_data_free(data); goto bad_tree; } /* * In this pass initialize all the tree levels and whether anyPolicy and * policy mapping are inhibited at each level. */ for (i = n - 1; i >= 0; i--) { X509 *x = sk_X509_value(certs, i); uint32_t ex_flags = X509_get_extension_flags(x); /* Access the cache which we now know exists */ cache = ossl_policy_cache_set(x); X509_up_ref(x); (++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 only if certificate is self issued and not * the last in the chain. */ if (!(ex_flags & EXFLAG_SI) || (i == 0)) level->flags |= X509_V_FLAG_INHIBIT_ANY; } else { if (!(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 (!(ex_flags & EXFLAG_SI)) map_skip--; if ((cache->map_skip >= 0) && (cache->map_skip < map_skip)) map_skip = cache->map_skip; } } *ptree = tree; return ret; bad_tree: X509_policy_tree_free(tree); return X509_PCY_TREE_INTERNAL; } /* * Return value: 1 on success, 0 otherwise */ static int tree_link_matching_nodes(X509_POLICY_LEVEL *curr, X509_POLICY_DATA *data, X509_POLICY_TREE *tree) { X509_POLICY_LEVEL *last = curr - 1; int i, matched = 0; /* Iterate through all in nodes linking matches */ for (i = 0; i < sk_X509_POLICY_NODE_num(last->nodes); i++) { X509_POLICY_NODE *node = sk_X509_POLICY_NODE_value(last->nodes, i); if (ossl_policy_node_match(last, node, data->valid_policy)) { if (ossl_policy_level_add_node(curr, data, node, tree, 0) == NULL) return 0; matched = 1; } } if (!matched && last->anyPolicy) { if (ossl_policy_level_add_node(curr, data, last->anyPolicy, tree, 0) == 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. * * Return value: 1 on success, 0 otherwise. */ static int tree_link_nodes(X509_POLICY_LEVEL *curr, const X509_POLICY_CACHE *cache, X509_POLICY_TREE *tree) { int i; for (i = 0; i < sk_X509_POLICY_DATA_num(cache->data); i++) { X509_POLICY_DATA *data = sk_X509_POLICY_DATA_value(cache->data, i); /* Look for matching nodes in previous level */ if (!tree_link_matching_nodes(curr, data, tree)) 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. * * Return value: 1 on success, 0 otherwise. */ 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. */ if ((data = ossl_policy_data_new(NULL, id, node_critical(node))) == NULL) return 0; /* Curr may not have anyPolicy */ data->qualifier_set = cache->anyPolicy->qualifier_set; data->flags |= POLICY_DATA_FLAG_SHARED_QUALIFIERS; if (ossl_policy_level_add_node(curr, data, node, tree, 1) == NULL) { ossl_policy_data_free(data); return 0; } return 1; } /* * Return value: 1 on success, 0 otherwise. */ 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 (ossl_policy_level_find_node(curr, node, oid)) continue; if (!tree_add_unmatched(curr, cache, oid, node, tree)) return 0; } } return 1; } /* * Return value: 1 on success, 0 otherwise */ 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 && ossl_policy_level_add_node(curr, cache->anyPolicy, last->anyPolicy, tree, 0) == 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. * * Return value: <= 0 error, otherwise one of: * * X509_PCY_TREE_VALID: valid tree * X509_PCY_TREE_EMPTY: empty tree */ 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--; OPENSSL_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--; OPENSSL_free(node); (void)sk_X509_POLICY_NODE_delete(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 X509_PCY_TREE_EMPTY; break; } } return X509_PCY_TREE_VALID; } /* * Return value: 1 on success, 0 otherwise. */ static int tree_add_auth_node(STACK_OF(X509_POLICY_NODE) **pnodes, X509_POLICY_NODE *pcy) { if (*pnodes == NULL && (*pnodes = ossl_policy_node_cmp_new()) == NULL) return 0; if (sk_X509_POLICY_NODE_find(*pnodes, pcy) >= 0) return 1; return sk_X509_POLICY_NODE_push(*pnodes, pcy) != 0; } #define TREE_CALC_FAILURE 0 #define TREE_CALC_OK_NOFREE 1 #define TREE_CALC_OK_DOFREE 2 /*- * 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. * * Return value: * TREE_CALC_FAILURE on failure, * TREE_CALC_OK_NOFREE on success and pnodes need not be freed, * TREE_CALC_OK_DOFREE on success and pnodes needs to 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 TREE_CALC_FAILURE; 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 level it can't appear on lower * levels so end search. */ if ((anyptr = curr->anyPolicy) == NULL) 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)) { if (addnodes == pnodes) { sk_X509_POLICY_NODE_free(*pnodes); *pnodes = NULL; } return TREE_CALC_FAILURE; } } } if (addnodes == pnodes) return TREE_CALC_OK_DOFREE; *pnodes = tree->auth_policies; return TREE_CALC_OK_NOFREE; } /* * Return value: 1 on success, 0 otherwise. */ 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 = ossl_policy_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 = ossl_policy_data_new(NULL, oid, node_critical(anyPolicy)); if (extra == NULL) return 0; extra->qualifier_set = anyPolicy->data->qualifier_set; extra->flags = POLICY_DATA_FLAG_SHARED_QUALIFIERS | POLICY_DATA_FLAG_EXTRA_NODE; node = ossl_policy_level_add_node(NULL, extra, anyPolicy->parent, tree, 1); if (node == NULL) { ossl_policy_data_free(extra); return 0; } } if (!tree->user_policies) { tree->user_policies = sk_X509_POLICY_NODE_new_null(); if (!tree->user_policies) { exnode_free(node); return 0; } } if (!sk_X509_POLICY_NODE_push(tree->user_policies, node)) { exnode_free(node); return 0; } } return 1; } /*- * Return value: <= 0 error, otherwise one of: * X509_PCY_TREE_VALID: valid tree * X509_PCY_TREE_EMPTY: empty tree * (see tree_prune()). */ 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 = ossl_policy_cache_set(curr->cert); if (!tree_link_nodes(curr, cache, tree)) return X509_PCY_TREE_INTERNAL; if (!(curr->flags & X509_V_FLAG_INHIBIT_ANY) && !tree_link_any(curr, cache, tree)) return X509_PCY_TREE_INTERNAL; TREE_PRINT("before tree_prune()", tree, curr); ret = tree_prune(tree, curr); if (ret != X509_PCY_TREE_VALID) return ret; } return X509_PCY_TREE_VALID; } 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++) { X509_free(curr->cert); sk_X509_POLICY_NODE_pop_free(curr->nodes, ossl_policy_node_free); ossl_policy_node_free(curr->anyPolicy); } sk_X509_POLICY_DATA_pop_free(tree->extra_data, ossl_policy_data_free); OPENSSL_free(tree->levels); OPENSSL_free(tree); } /*- * Application policy checking function. * Return codes: * X509_PCY_TREE_FAILURE: Failure to satisfy explicit policy * X509_PCY_TREE_INVALID: Inconsistent or invalid extensions * X509_PCY_TREE_INTERNAL: Internal error, most likely malloc * X509_PCY_TREE_VALID: Success (null tree if empty or bare TA) */ 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 init_ret; int ret; int calc_ret; X509_POLICY_TREE *tree = NULL; STACK_OF(X509_POLICY_NODE) *nodes, *auth_nodes = NULL; *ptree = NULL; *pexplicit_policy = 0; init_ret = tree_init(&tree, certs, flags); if (init_ret <= 0) return init_ret; if ((init_ret & X509_PCY_TREE_EXPLICIT) == 0) { if (init_ret & X509_PCY_TREE_EMPTY) { X509_policy_tree_free(tree); return X509_PCY_TREE_VALID; } } else { *pexplicit_policy = 1; /* Tree empty and requireExplicit True: Error */ if (init_ret & X509_PCY_TREE_EMPTY) return X509_PCY_TREE_FAILURE; } ret = tree_evaluate(tree); TREE_PRINT("tree_evaluate()", tree, NULL); if (ret <= 0) goto error; if (ret == X509_PCY_TREE_EMPTY) { X509_policy_tree_free(tree); if (init_ret & X509_PCY_TREE_EXPLICIT) return X509_PCY_TREE_FAILURE; return X509_PCY_TREE_VALID; } /* Tree is not empty: continue */ if ((calc_ret = tree_calculate_authority_set(tree, &auth_nodes)) == 0) goto error; sk_X509_POLICY_NODE_sort(auth_nodes); ret = tree_calculate_user_set(tree, policy_oids, auth_nodes); if (calc_ret == TREE_CALC_OK_DOFREE) sk_X509_POLICY_NODE_free(auth_nodes); if (!ret) goto error; *ptree = tree; if (init_ret & X509_PCY_TREE_EXPLICIT) { nodes = X509_policy_tree_get0_user_policies(tree); if (sk_X509_POLICY_NODE_num(nodes) <= 0) return X509_PCY_TREE_FAILURE; } return X509_PCY_TREE_VALID; error: X509_policy_tree_free(tree); return X509_PCY_TREE_INTERNAL; }