--- /dev/null
+/* Copyright (c) 2022, Google Inc.
+ *
+ * Permission to use, copy, modify, and/or distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
+ * SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION
+ * OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
+ * CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. */
+
+#include <openssl/x509.h>
+
+#include <assert.h>
+
+#include <openssl/mem.h>
+#include <openssl/obj.h>
+#include <openssl/stack.h>
+#include <openssl/x509v3.h>
+
+#include "../internal.h"
+#include "../x509v3/internal.h"
+#include "internal.h"
+
+
+// This file computes the X.509 policy tree, as described in RFC 5280, section
+// 6.1. It differs in that:
+//
+// (1) It does not track "qualifier_set". This is not needed as it is not
+// output by this implementation.
+//
+// (2) It builds a directed acyclic graph, rather than a tree. When a given
+// policy matches multiple parents, RFC 5280 makes a separate node for
+// each parent. This representation condenses them into one node with
+// multiple parents. Thus we refer to this structure as a "policy graph",
+// rather than a "policy tree".
+//
+// (3) "expected_policy_set" is not tracked explicitly and built temporarily
+// as part of building the graph.
+//
+// (4) anyPolicy nodes are not tracked explicitly.
+//
+// (5) Some pruning steps are deferred to when policies are evaluated, as a
+// reachability pass.
+
+// An X509_POLICY_NODE is a node in the policy graph. It corresponds to a node
+// from RFC 5280, section 6.1.2, step (a), but we store some fields differently.
+typedef struct x509_policy_node_st {
+ // policy is the "valid_policy" field from RFC 5280.
+ ASN1_OBJECT *policy;
+
+ // parent_policies, if non-empty, is the list of "valid_policy" values for all
+ // nodes which are a parent of this node. In this case, no entry in this list
+ // will be anyPolicy. This list is in no particular order and may contain
+ // duplicates if the corresponding certificate had duplicate mappings.
+ //
+ // If empty, this node has a single parent, anyPolicy. The node is then a root
+ // policies, and is in authorities-constrained-policy-set if it has a path to
+ // a leaf node.
+ //
+ // Note it is not possible for a policy to have both anyPolicy and a
+ // concrete policy as a parent. Section 6.1.3, step (d.1.ii) only runs if
+ // there was no match in step (d.1.i). We do not need to represent a parent
+ // list of, say, {anyPolicy, OID1, OID2}.
+ STACK_OF(ASN1_OBJECT) *parent_policies;
+
+ // mapped is one if this node matches a policy mapping in the certificate and
+ // zero otherwise.
+ int mapped;
+
+ // reachable is one if this node is reachable from some valid policy in the
+ // end-entity certificate. It is computed during |has_explicit_policy|.
+ int reachable;
+} X509_POLICY_NODE;
+
+DEFINE_STACK_OF(X509_POLICY_NODE)
+
+// An X509_POLICY_LEVEL is the collection of nodes at the same depth in the
+// policy graph. This structure can also be used to represent a level's
+// "expected_policy_set" values. See |process_policy_mappings|.
+typedef struct x509_policy_level_st {
+ // nodes is the list of nodes at this depth, except for the anyPolicy node, if
+ // any. This list is sorted by policy OID for efficient lookup.
+ STACK_OF(X509_POLICY_NODE) *nodes;
+
+ // has_any_policy is one if there is an anyPolicy node at this depth, and zero
+ // otherwise.
+ int has_any_policy;
+} X509_POLICY_LEVEL;
+
+DEFINE_STACK_OF(X509_POLICY_LEVEL)
+
+static int is_any_policy(const ASN1_OBJECT *obj) {
+ return OBJ_obj2nid(obj) == NID_any_policy;
+}
+
+static void x509_policy_node_free(X509_POLICY_NODE *node) {
+ if (node != NULL) {
+ ASN1_OBJECT_free(node->policy);
+ sk_ASN1_OBJECT_pop_free(node->parent_policies, ASN1_OBJECT_free);
+ OPENSSL_free(node);
+ }
+}
+
+static X509_POLICY_NODE *x509_policy_node_new(const ASN1_OBJECT *policy) {
+ assert(!is_any_policy(policy));
+ X509_POLICY_NODE *node = OPENSSL_malloc(sizeof(X509_POLICY_NODE));
+ if (node == NULL) {
+ return NULL;
+ }
+ OPENSSL_memset(node, 0, sizeof(X509_POLICY_NODE));
+ node->policy = OBJ_dup(policy);
+ node->parent_policies = sk_ASN1_OBJECT_new_null();
+ if (node->policy == NULL || node->parent_policies == NULL) {
+ x509_policy_node_free(node);
+ return NULL;
+ }
+ return node;
+}
+
+static int x509_policy_node_cmp(const X509_POLICY_NODE *const *a,
+ const X509_POLICY_NODE *const *b) {
+ return OBJ_cmp((*a)->policy, (*b)->policy);
+}
+
+static void x509_policy_level_free(X509_POLICY_LEVEL *level) {
+ if (level != NULL) {
+ sk_X509_POLICY_NODE_pop_free(level->nodes, x509_policy_node_free);
+ OPENSSL_free(level);
+ }
+}
+
+static X509_POLICY_LEVEL *x509_policy_level_new(void) {
+ X509_POLICY_LEVEL *level = OPENSSL_malloc(sizeof(X509_POLICY_LEVEL));
+ if (level == NULL) {
+ return NULL;
+ }
+ OPENSSL_memset(level, 0, sizeof(X509_POLICY_LEVEL));
+ level->nodes = sk_X509_POLICY_NODE_new(x509_policy_node_cmp);
+ if (level->nodes == NULL) {
+ x509_policy_level_free(level);
+ return NULL;
+ }
+ return level;
+}
+
+static int x509_policy_level_is_empty(const X509_POLICY_LEVEL *level) {
+ return !level->has_any_policy && sk_X509_POLICY_NODE_num(level->nodes) == 0;
+}
+
+static void x509_policy_level_clear(X509_POLICY_LEVEL *level) {
+ level->has_any_policy = 0;
+ for (size_t i = 0; i < sk_X509_POLICY_NODE_num(level->nodes); i++) {
+ x509_policy_node_free(sk_X509_POLICY_NODE_value(level->nodes, i));
+ }
+ sk_X509_POLICY_NODE_zero(level->nodes);
+}
+
+// x509_policy_level_find returns the node in |level| corresponding to |policy|,
+// or NULL if none exists.
+static X509_POLICY_NODE *x509_policy_level_find(X509_POLICY_LEVEL *level,
+ const ASN1_OBJECT *policy) {
+ assert(sk_X509_POLICY_NODE_is_sorted(level->nodes));
+ X509_POLICY_NODE node;
+ node.policy = (ASN1_OBJECT *)policy;
+ size_t idx;
+ if (!sk_X509_POLICY_NODE_find(level->nodes, &idx, &node)) {
+ return NULL;
+ }
+ return sk_X509_POLICY_NODE_value(level->nodes, idx);
+}
+
+// x509_policy_level_add_nodes adds the nodes in |nodes| to |level|. It returns
+// one on success and zero on error. No policy in |nodes| may already be present
+// in |level|. This function modifies |nodes| to avoid making a copy, but the
+// caller is still responsible for releasing |nodes| itself.
+//
+// This function is used to add nodes to |level| in bulk, and avoid resorting
+// |level| after each addition.
+static int x509_policy_level_add_nodes(X509_POLICY_LEVEL *level,
+ STACK_OF(X509_POLICY_NODE) *nodes) {
+ for (size_t i = 0; i < sk_X509_POLICY_NODE_num(nodes); i++) {
+ X509_POLICY_NODE *node = sk_X509_POLICY_NODE_value(nodes, i);
+ if (!sk_X509_POLICY_NODE_push(level->nodes, node)) {
+ return 0;
+ }
+ sk_X509_POLICY_NODE_set(nodes, i, NULL);
+ }
+ sk_X509_POLICY_NODE_sort(level->nodes);
+
+#if !defined(NDEBUG)
+ // There should be no duplicate nodes.
+ for (size_t i = 1; i < sk_X509_POLICY_NODE_num(level->nodes); i++) {
+ assert(OBJ_cmp(sk_X509_POLICY_NODE_value(level->nodes, i - 1)->policy,
+ sk_X509_POLICY_NODE_value(level->nodes, i)->policy) != 0);
+ }
+#endif
+ return 1;
+}
+
+static int policyinfo_cmp(const POLICYINFO *const *a,
+ const POLICYINFO *const *b) {
+ return OBJ_cmp((*a)->policyid, (*b)->policyid);
+}
+
+static int delete_if_not_in_policies(X509_POLICY_NODE *node, void *data) {
+ const CERTIFICATEPOLICIES *policies = data;
+ assert(sk_POLICYINFO_is_sorted(policies));
+ POLICYINFO info;
+ info.policyid = node->policy;
+ if (sk_POLICYINFO_find(policies, NULL, &info)) {
+ return 0;
+ }
+ x509_policy_node_free(node);
+ return 1;
+}
+
+// process_certificate_policies updates |level| to incorporate |x509|'s
+// certificate policies extension. This implements steps (d) and (e) of RFC
+// 5280, section 6.1.3. |level| must contain the previous level's
+// "expected_policy_set" information. For all but the top-most level, this is
+// the output of |process_policy_mappings|. |any_policy_allowed| specifies
+// whether anyPolicy is allowed or inhibited, taking into account the exception
+// for self-issued certificates.
+static int process_certificate_policies(const X509 *x509,
+ X509_POLICY_LEVEL *level,
+ int any_policy_allowed) {
+ int ret = 0;
+ int critical;
+ STACK_OF(X509_POLICY_NODE) *new_nodes = NULL;
+ CERTIFICATEPOLICIES *policies =
+ X509_get_ext_d2i(x509, NID_certificate_policies, &critical, NULL);
+ if (policies == NULL) {
+ if (critical != -1) {
+ return 0; // Syntax error in the extension.
+ }
+
+ // RFC 5280, section 6.1.3, step (e).
+ x509_policy_level_clear(level);
+ return 1;
+ }
+
+ // certificatePolicies may not be empty. See RFC 5280, section 4.2.1.4.
+ // TODO(https://crbug.com/boringssl/443): Move this check into the parser.
+ if (sk_POLICYINFO_num(policies) == 0) {
+ OPENSSL_PUT_ERROR(X509, X509_R_INVALID_POLICY_EXTENSION);
+ goto err;
+ }
+
+ sk_POLICYINFO_set_cmp_func(policies, policyinfo_cmp);
+ sk_POLICYINFO_sort(policies);
+ int cert_has_any_policy = 0;
+ for (size_t i = 0; i < sk_POLICYINFO_num(policies); i++) {
+ const POLICYINFO *policy = sk_POLICYINFO_value(policies, i);
+ if (is_any_policy(policy->policyid)) {
+ cert_has_any_policy = 1;
+ }
+ if (i > 0 && OBJ_cmp(sk_POLICYINFO_value(policies, i - 1)->policyid,
+ policy->policyid) == 0) {
+ // Per RFC 5280, section 4.2.1.4, |policies| may not have duplicates.
+ OPENSSL_PUT_ERROR(X509, X509_R_INVALID_POLICY_EXTENSION);
+ goto err;
+ }
+ }
+
+ // This does the same thing as RFC 5280, section 6.1.3, step (d), though in
+ // a slighty different order. |level| currently contains "expected_policy_set"
+ // values of the previous level. See |process_policy_mappings| for details.
+ const int previous_level_has_any_policy = level->has_any_policy;
+
+ // First, we handle steps (d.1.i) and (d.2). The net effect of these two steps
+ // is to intersect |level| with |policies|, ignoring anyPolicy if it is
+ // inhibited.
+ if (!cert_has_any_policy || !any_policy_allowed) {
+ sk_X509_POLICY_NODE_delete_if(level->nodes, delete_if_not_in_policies,
+ policies);
+ level->has_any_policy = 0;
+ }
+
+ // Step (d.1.ii) may attach new nodes to the previous level's anyPolicy node.
+ if (previous_level_has_any_policy) {
+ new_nodes = sk_X509_POLICY_NODE_new_null();
+ if (new_nodes == NULL) {
+ goto err;
+ }
+ for (size_t i = 0; i < sk_POLICYINFO_num(policies); i++) {
+ const POLICYINFO *policy = sk_POLICYINFO_value(policies, i);
+ // Though we've reordered the steps slightly, |policy| is in |level| if
+ // and only if it would have been a match in step (d.1.ii).
+ if (!is_any_policy(policy->policyid) &&
+ x509_policy_level_find(level, policy->policyid) == NULL) {
+ X509_POLICY_NODE *node = x509_policy_node_new(policy->policyid);
+ if (node == NULL || //
+ !sk_X509_POLICY_NODE_push(new_nodes, node)) {
+ x509_policy_node_free(node);
+ goto err;
+ }
+ }
+ }
+ if (!x509_policy_level_add_nodes(level, new_nodes)) {
+ goto err;
+ }
+ }
+
+ ret = 1;
+
+err:
+ sk_X509_POLICY_NODE_pop_free(new_nodes, x509_policy_node_free);
+ CERTIFICATEPOLICIES_free(policies);
+ return ret;
+}
+
+static int compare_issuer_policy(const POLICY_MAPPING *const *a,
+ const POLICY_MAPPING *const *b) {
+ return OBJ_cmp((*a)->issuerDomainPolicy, (*b)->issuerDomainPolicy);
+}
+
+static int compare_subject_policy(const POLICY_MAPPING *const *a,
+ const POLICY_MAPPING *const *b) {
+ return OBJ_cmp((*a)->subjectDomainPolicy, (*b)->subjectDomainPolicy);
+}
+
+static int delete_if_mapped(X509_POLICY_NODE *node, void *data) {
+ const POLICY_MAPPINGS *mappings = data;
+ // |mappings| must have been sorted by |compare_issuer_policy|.
+ assert(sk_POLICY_MAPPING_is_sorted(mappings));
+ POLICY_MAPPING mapping;
+ mapping.issuerDomainPolicy = node->policy;
+ if (!sk_POLICY_MAPPING_find(mappings, /*out_index=*/NULL, &mapping)) {
+ return 0;
+ }
+ x509_policy_node_free(node);
+ return 1;
+}
+
+// process_policy_mappings processes the policy mappings extension of |cert|,
+// whose corresponding graph level is |level|. |mapping_allowed| specifies
+// whether policy mapping is inhibited at this point. On success, it returns an
+// |X509_POLICY_LEVEL| containing the "expected_policy_set" for |level|. On
+// error, it returns NULL. This implements steps (a) and (b) of RFC 5280,
+// section 6.1.4.
+//
+// We represent the "expected_policy_set" as an |X509_POLICY_LEVEL|.
+// |has_any_policy| indicates whether there is an anyPolicy node with
+// "expected_policy_set" of {anyPolicy}. If a node with policy oid P1 contains
+// P2 in its "expected_policy_set", the level will contain a node of policy P2
+// with P1 in |parent_policies|.
+//
+// This is equivalent to the |X509_POLICY_LEVEL| that would result if the next
+// certificats contained anyPolicy. |process_certificate_policies| will filter
+// this result down to compute the actual level.
+static X509_POLICY_LEVEL *process_policy_mappings(const X509 *cert,
+ X509_POLICY_LEVEL *level,
+ int mapping_allowed) {
+ int ok = 0;
+ STACK_OF(X509_POLICY_NODE) *new_nodes = NULL;
+ X509_POLICY_LEVEL *next = NULL;
+ int critical;
+ POLICY_MAPPINGS *mappings =
+ X509_get_ext_d2i(cert, NID_policy_mappings, &critical, NULL);
+ if (mappings == NULL && critical != -1) {
+ // Syntax error in the policy mappings extension.
+ goto err;
+ }
+
+ if (mappings != NULL) {
+ // PolicyMappings may not be empty. See RFC 5280, section 4.2.1.5.
+ // TODO(https://crbug.com/boringssl/443): Move this check into the parser.
+ if (sk_POLICY_MAPPING_num(mappings) == 0) {
+ OPENSSL_PUT_ERROR(X509, X509_R_INVALID_POLICY_EXTENSION);
+ goto err;
+ }
+
+ // RFC 5280, section 6.1.4, step (a).
+ for (size_t i = 0; i < sk_POLICY_MAPPING_num(mappings); i++) {
+ POLICY_MAPPING *mapping = sk_POLICY_MAPPING_value(mappings, i);
+ if (is_any_policy(mapping->issuerDomainPolicy) ||
+ is_any_policy(mapping->subjectDomainPolicy)) {
+ goto err;
+ }
+ }
+
+ // Sort to group by issuerDomainPolicy.
+ sk_POLICY_MAPPING_set_cmp_func(mappings, compare_issuer_policy);
+ sk_POLICY_MAPPING_sort(mappings);
+
+ if (mapping_allowed) {
+ // Mark nodes as mapped, and add any nodes to |level| which may be needed
+ // as part of RFC 5280, section 6.1.4, step (b.1).
+ new_nodes = sk_X509_POLICY_NODE_new_null();
+ if (new_nodes == NULL) {
+ goto err;
+ }
+ const ASN1_OBJECT *last_policy = NULL;
+ for (size_t i = 0; i < sk_POLICY_MAPPING_num(mappings); i++) {
+ const POLICY_MAPPING *mapping = sk_POLICY_MAPPING_value(mappings, i);
+ // There may be multiple mappings with the same |issuerDomainPolicy|.
+ if (last_policy != NULL &&
+ OBJ_cmp(mapping->issuerDomainPolicy, last_policy) == 0) {
+ continue;
+ }
+ last_policy = mapping->issuerDomainPolicy;
+
+ X509_POLICY_NODE *node =
+ x509_policy_level_find(level, mapping->issuerDomainPolicy);
+ if (node == NULL) {
+ if (!level->has_any_policy) {
+ continue;
+ }
+ node = x509_policy_node_new(mapping->issuerDomainPolicy);
+ if (node == NULL || //
+ !sk_X509_POLICY_NODE_push(new_nodes, node)) {
+ x509_policy_node_free(node);
+ goto err;
+ }
+ }
+ node->mapped = 1;
+ }
+ if (!x509_policy_level_add_nodes(level, new_nodes)) {
+ goto err;
+ }
+ } else {
+ // RFC 5280, section 6.1.4, step (b.2). If mapping is inhibited, delete
+ // all mapped nodes.
+ sk_X509_POLICY_NODE_delete_if(level->nodes, delete_if_mapped, mappings);
+ sk_POLICY_MAPPING_pop_free(mappings, POLICY_MAPPING_free);
+ mappings = NULL;
+ }
+ }
+
+ // If a node was not mapped, it retains the original "explicit_policy_set"
+ // value, itself. Add those to |mappings|.
+ if (mappings == NULL) {
+ mappings = sk_POLICY_MAPPING_new_null();
+ if (mappings == NULL) {
+ goto err;
+ }
+ }
+ for (size_t i = 0; i < sk_X509_POLICY_NODE_num(level->nodes); i++) {
+ X509_POLICY_NODE *node = sk_X509_POLICY_NODE_value(level->nodes, i);
+ if (!node->mapped) {
+ POLICY_MAPPING *mapping = POLICY_MAPPING_new();
+ if (mapping == NULL) {
+ goto err;
+ }
+ mapping->issuerDomainPolicy = OBJ_dup(node->policy);
+ mapping->subjectDomainPolicy = OBJ_dup(node->policy);
+ if (mapping->issuerDomainPolicy == NULL ||
+ mapping->subjectDomainPolicy == NULL ||
+ !sk_POLICY_MAPPING_push(mappings, mapping)) {
+ POLICY_MAPPING_free(mapping);
+ goto err;
+ }
+ }
+ }
+
+ // Sort to group by subjectDomainPolicy.
+ sk_POLICY_MAPPING_set_cmp_func(mappings, compare_subject_policy);
+ sk_POLICY_MAPPING_sort(mappings);
+
+ // Convert |mappings| to our "expected_policy_set" representation.
+ next = x509_policy_level_new();
+ if (next == NULL) {
+ goto err;
+ }
+ next->has_any_policy = level->has_any_policy;
+
+ X509_POLICY_NODE *last_node = NULL;
+ for (size_t i = 0; i < sk_POLICY_MAPPING_num(mappings); i++) {
+ POLICY_MAPPING *mapping = sk_POLICY_MAPPING_value(mappings, i);
+ // Skip mappings where |issuerDomainPolicy| does not appear in the graph.
+ if (!level->has_any_policy &&
+ x509_policy_level_find(level, mapping->issuerDomainPolicy) == NULL) {
+ continue;
+ }
+
+ if (last_node == NULL ||
+ OBJ_cmp(last_node->policy, mapping->subjectDomainPolicy) != 0) {
+ last_node = x509_policy_node_new(mapping->subjectDomainPolicy);
+ if (last_node == NULL ||
+ !sk_X509_POLICY_NODE_push(next->nodes, last_node)) {
+ x509_policy_node_free(last_node);
+ goto err;
+ }
+ }
+
+ if (!sk_ASN1_OBJECT_push(last_node->parent_policies,
+ mapping->issuerDomainPolicy)) {
+ goto err;
+ }
+ mapping->issuerDomainPolicy = NULL;
+ }
+
+ sk_X509_POLICY_NODE_sort(next->nodes);
+ ok = 1;
+
+err:
+ if (!ok) {
+ x509_policy_level_free(next);
+ next = NULL;
+ }
+
+ sk_POLICY_MAPPING_pop_free(mappings, POLICY_MAPPING_free);
+ sk_X509_POLICY_NODE_pop_free(new_nodes, x509_policy_node_free);
+ return next;
+}
+
+// apply_skip_certs, if |skip_certs| is non-NULL, sets |*value| to the minimum
+// of its current value and |skip_certs|. It returns one on success and zero if
+// |skip_certs| is negative.
+static int apply_skip_certs(const ASN1_INTEGER *skip_certs, size_t *value) {
+ if (skip_certs == NULL) {
+ return 1;
+ }
+
+ // TODO(https://crbug.com/boringssl/443): Move this check into the parser.
+ if (skip_certs->type & V_ASN1_NEG) {
+ OPENSSL_PUT_ERROR(X509, X509_R_INVALID_POLICY_EXTENSION);
+ return 0;
+ }
+
+ // If |skip_certs| does not fit in |uint64_t|, it must exceed |*value|.
+ uint64_t u64;
+ if (ASN1_INTEGER_get_uint64(&u64, skip_certs) && u64 < *value) {
+ *value = (size_t)u64;
+ }
+ ERR_clear_error();
+ return 1;
+}
+
+// process_policy_constraints updates |*explicit_policy|, |*policy_mapping|, and
+// |*inhibit_any_policy| according to |x509|'s policy constraints and inhibit
+// anyPolicy extensions. It returns one on success and zero on error. This
+// implements steps (i) and (j) of RFC 5280, section 6.1.4.
+static int process_policy_constraints(const X509 *x509, size_t *explicit_policy,
+ size_t *policy_mapping,
+ size_t *inhibit_any_policy) {
+ int critical;
+ POLICY_CONSTRAINTS *constraints =
+ X509_get_ext_d2i(x509, NID_policy_constraints, &critical, NULL);
+ if (constraints == NULL && critical != -1) {
+ return 0;
+ }
+ if (constraints != NULL) {
+ if (constraints->requireExplicitPolicy == NULL &&
+ constraints->inhibitPolicyMapping == NULL) {
+ // Per RFC 5280, section 4.2.1.11, at least one of the fields must be
+ // present.
+ OPENSSL_PUT_ERROR(X509, X509_R_INVALID_POLICY_EXTENSION);
+ POLICY_CONSTRAINTS_free(constraints);
+ return 0;
+ }
+ int ok =
+ apply_skip_certs(constraints->requireExplicitPolicy, explicit_policy) &&
+ apply_skip_certs(constraints->inhibitPolicyMapping, policy_mapping);
+ POLICY_CONSTRAINTS_free(constraints);
+ if (!ok) {
+ return 0;
+ }
+ }
+
+ ASN1_INTEGER *inhibit_any_policy_ext =
+ X509_get_ext_d2i(x509, NID_inhibit_any_policy, &critical, NULL);
+ if (inhibit_any_policy_ext == NULL && critical != -1) {
+ return 0;
+ }
+ int ok = apply_skip_certs(inhibit_any_policy_ext, inhibit_any_policy);
+ ASN1_INTEGER_free(inhibit_any_policy_ext);
+ return ok;
+}
+
+// has_explicit_policy returns one if the set of authority-space policy OIDs
+// |levels| has some non-empty intersection with |user_policies|, and zero
+// otherwise. This mirrors the logic in RFC 5280, section 6.1.5, step (g). This
+// function modifies |levels| and should only be called at the end of policy
+// evaluation.
+static int has_explicit_policy(STACK_OF(X509_POLICY_LEVEL) *levels,
+ const STACK_OF(ASN1_OBJECT) *user_policies) {
+ assert(user_policies == NULL || sk_ASN1_OBJECT_is_sorted(user_policies));
+
+ // Step (g.i). If the policy graph is empty, the intersection is empty.
+ size_t num_levels = sk_X509_POLICY_LEVEL_num(levels);
+ X509_POLICY_LEVEL *level = sk_X509_POLICY_LEVEL_value(levels, num_levels - 1);
+ if (x509_policy_level_is_empty(level)) {
+ return 0;
+ }
+
+ // If |user_policies| is empty, we interpret it as having a single anyPolicy
+ // value. The caller may also have supplied anyPolicy explicitly.
+ int user_has_any_policy = sk_ASN1_OBJECT_num(user_policies) == 0;
+ for (size_t i = 0; i < sk_ASN1_OBJECT_num(user_policies); i++) {
+ if (is_any_policy(sk_ASN1_OBJECT_value(user_policies, i))) {
+ user_has_any_policy = 1;
+ break;
+ }
+ }
+
+ // Step (g.ii). If the policy graph is not empty and the user set contains
+ // anyPolicy, the intersection is the entire (non-empty) graph.
+ if (user_has_any_policy) {
+ return 1;
+ }
+
+ // Step (g.iii) does not delete anyPolicy nodes, so if the graph has
+ // anyPolicy, some explicit policy will survive. The actual intersection may
+ // synthesize some nodes in step (g.iii.3), but we do not return the policy
+ // list itself, so we skip actually computing this.
+ if (level->has_any_policy) {
+ return 1;
+ }
+
+ // We defer pruning the tree, so as we look for nodes with parent anyPolicy,
+ // step (g.iii.1), we must limit to nodes reachable from the bottommost level.
+ // Start by marking each of those nodes as reachable.
+ for (size_t i = 0; i < sk_X509_POLICY_NODE_num(level->nodes); i++) {
+ sk_X509_POLICY_NODE_value(level->nodes, i)->reachable = 1;
+ }
+
+ for (size_t i = num_levels - 1; i < num_levels; i--) {
+ level = sk_X509_POLICY_LEVEL_value(levels, i);
+ for (size_t j = 0; j < sk_X509_POLICY_NODE_num(level->nodes); j++) {
+ X509_POLICY_NODE *node = sk_X509_POLICY_NODE_value(level->nodes, j);
+ if (!node->reachable) {
+ continue;
+ }
+ if (sk_ASN1_OBJECT_num(node->parent_policies) == 0) {
+ // |node|'s parent is anyPolicy and is part of "valid_policy_node_set".
+ // If it exists in |user_policies|, the intersection is non-empty and we
+ // can return immediately.
+ if (sk_ASN1_OBJECT_find(user_policies, /*out_index=*/NULL,
+ node->policy)) {
+ return 1;
+ }
+ } else if (i > 0) {
+ // |node|'s parents are concrete policies. Mark the parents reachable,
+ // to be inspected by the next loop iteration.
+ X509_POLICY_LEVEL *prev = sk_X509_POLICY_LEVEL_value(levels, i - 1);
+ for (size_t k = 0; k < sk_ASN1_OBJECT_num(node->parent_policies); k++) {
+ X509_POLICY_NODE *parent = x509_policy_level_find(
+ prev, sk_ASN1_OBJECT_value(node->parent_policies, k));
+ if (parent != NULL) {
+ parent->reachable = 1;
+ }
+ }
+ }
+ }
+ }
+
+ return 0;
+}
+
+static int asn1_object_cmp(const ASN1_OBJECT *const *a,
+ const ASN1_OBJECT *const *b) {
+ return OBJ_cmp(*a, *b);
+}
+
+int X509_policy_check(const STACK_OF(X509) *certs,
+ const STACK_OF(ASN1_OBJECT) *user_policies,
+ unsigned long flags, X509 **out_current_cert) {
+ *out_current_cert = NULL;
+ int ret = X509_V_ERR_OUT_OF_MEM;
+ X509_POLICY_LEVEL *level = NULL;
+ STACK_OF(X509_POLICY_LEVEL) *levels = NULL;
+ STACK_OF(ASN1_OBJECT) *user_policies_sorted = NULL;
+ size_t num_certs = sk_X509_num(certs);
+
+ // Skip policy checking if the chain is just the trust anchor.
+ if (num_certs <= 1) {
+ return X509_V_OK;
+ }
+
+ // See RFC 5280, section 6.1.2, steps (d) through (f).
+ size_t explicit_policy =
+ (flags & X509_V_FLAG_EXPLICIT_POLICY) ? 0 : num_certs + 1;
+ size_t inhibit_any_policy =
+ (flags & X509_V_FLAG_INHIBIT_ANY) ? 0 : num_certs + 1;
+ size_t policy_mapping =
+ (flags & X509_V_FLAG_INHIBIT_MAP) ? 0 : num_certs + 1;
+
+ levels = sk_X509_POLICY_LEVEL_new_null();
+ if (levels == NULL) {
+ goto err;
+ }
+
+ for (size_t i = num_certs - 2; i < num_certs; i--) {
+ X509 *cert = sk_X509_value(certs, i);
+ if (!x509v3_cache_extensions(cert)) {
+ goto err;
+ }
+ const int is_self_issued = (cert->ex_flags & EXFLAG_SI) != 0;
+
+ if (level == NULL) {
+ assert(i == num_certs - 2);
+ level = x509_policy_level_new();
+ if (level == NULL) {
+ goto err;
+ }
+ level->has_any_policy = 1;
+ }
+
+ // RFC 5280, section 6.1.3, steps (d) and (e). |any_policy_allowed| is
+ // computed as in step (d.2).
+ const int any_policy_allowed =
+ inhibit_any_policy > 0 || (i > 0 && is_self_issued);
+ if (!process_certificate_policies(cert, level, any_policy_allowed)) {
+ ret = X509_V_ERR_INVALID_POLICY_EXTENSION;
+ *out_current_cert = cert;
+ goto err;
+ }
+
+ // RFC 5280, section 6.1.3, step (f).
+ if (explicit_policy == 0 && x509_policy_level_is_empty(level)) {
+ ret = X509_V_ERR_NO_EXPLICIT_POLICY;
+ goto err;
+ }
+
+ // Insert into the list.
+ if (!sk_X509_POLICY_LEVEL_push(levels, level)) {
+ goto err;
+ }
+ X509_POLICY_LEVEL *current_level = level;
+ level = NULL;
+
+ // If this is not the leaf certificate, we go to section 6.1.4. If it
+ // is the leaf certificate, we go to section 6.1.5 instead.
+ if (i != 0) {
+ // RFC 5280, section 6.1.4, steps (a) and (b).
+ level = process_policy_mappings(cert, current_level, policy_mapping > 0);
+ if (level == NULL) {
+ ret = X509_V_ERR_INVALID_POLICY_EXTENSION;
+ *out_current_cert = cert;
+ goto err;
+ }
+ }
+
+ // RFC 5280, section 6.1.4, step (h-j) for non-leaves, and section 6.1.5,
+ // step (a-b) for leaves. In the leaf case, RFC 5280 says only to update
+ // |explicit_policy|, but |policy_mapping| and |inhibit_any_policy| are no
+ // longer read at this point, so we use the same process.
+ if (i == 0 || !is_self_issued) {
+ if (explicit_policy > 0) {
+ explicit_policy--;
+ }
+ if (policy_mapping > 0) {
+ policy_mapping--;
+ }
+ if (inhibit_any_policy > 0) {
+ inhibit_any_policy--;
+ }
+ }
+ if (!process_policy_constraints(cert, &explicit_policy, &policy_mapping,
+ &inhibit_any_policy)) {
+ ret = X509_V_ERR_INVALID_POLICY_EXTENSION;
+ *out_current_cert = cert;
+ goto err;
+ }
+ }
+
+ // RFC 5280, section 6.1.5, step (g). We do not output the policy set, so it
+ // is only necessary to check if the user-constrained-policy-set is not empty.
+ if (explicit_policy == 0) {
+ // Build a sorted copy of |user_policies| for more efficient lookup.
+ if (user_policies != NULL) {
+ user_policies_sorted = sk_ASN1_OBJECT_dup(user_policies);
+ if (user_policies_sorted == NULL) {
+ goto err;
+ }
+ sk_ASN1_OBJECT_set_cmp_func(user_policies_sorted, asn1_object_cmp);
+ sk_ASN1_OBJECT_sort(user_policies_sorted);
+ }
+
+ if (!has_explicit_policy(levels, user_policies_sorted)) {
+ ret = X509_V_ERR_NO_EXPLICIT_POLICY;
+ goto err;
+ }
+ }
+
+ ret = X509_V_OK;
+
+err:
+ x509_policy_level_free(level);
+ // |user_policies_sorted|'s contents are owned by |user_policies|, so we do
+ // not use |sk_ASN1_OBJECT_pop_free|.
+ sk_ASN1_OBJECT_free(user_policies_sorted);
+ sk_X509_POLICY_LEVEL_pop_free(levels, x509_policy_level_free);
+ return ret;
+}
projects / openbsd / commitdiff