ref: 009439541d2c6e8af2596f8fb1b4df85861fd212
dir: /third_party/boringssl/src/crypto/x509/policy.c/
/* 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 "../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_zalloc(sizeof(X509_POLICY_NODE));
if (node == NULL) {
return NULL;
}
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_zalloc(sizeof(X509_POLICY_LEVEL));
if (level == NULL) {
return NULL;
}
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;
}