222 строки
8.5 KiB
Diff
222 строки
8.5 KiB
Diff
From 879f7080d7e141f415c79eaa3a8ac4a3dad0348b Mon Sep 17 00:00:00 2001
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From: Pauli <pauli@openssl.org>
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Date: Wed, 8 Mar 2023 15:28:20 +1100
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Subject: [PATCH] x509: excessive resource use verifying policy constraints
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A security vulnerability has been identified in all supported versions
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of OpenSSL related to the verification of X.509 certificate chains
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that include policy constraints. Attackers may be able to exploit this
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vulnerability by creating a malicious certificate chain that triggers
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exponential use of computational resources, leading to a denial-of-service
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(DoS) attack on affected systems.
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Fixes CVE-2023-0464
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Reviewed-by: Tomas Mraz <tomas@openssl.org>
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Reviewed-by: Shane Lontis <shane.lontis@oracle.com>
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(Merged from https://github.com/openssl/openssl/pull/20569)
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---
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crypto/x509v3/pcy_local.h | 8 +++++++-
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crypto/x509v3/pcy_node.c | 12 +++++++++---
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crypto/x509v3/pcy_tree.c | 37 +++++++++++++++++++++++++++----------
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3 files changed, 43 insertions(+), 14 deletions(-)
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diff --git a/crypto/x509v3/pcy_local.h b/crypto/x509v3/pcy_local.h
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index 5daf78de45..344aa06765 100644
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--- a/crypto/x509v3/pcy_local.h
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+++ b/crypto/x509v3/pcy_local.h
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@@ -111,6 +111,11 @@ struct X509_POLICY_LEVEL_st {
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};
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struct X509_POLICY_TREE_st {
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+ /* The number of nodes in the tree */
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+ size_t node_count;
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+ /* The maximum number of nodes in the tree */
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+ size_t node_maximum;
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+
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/* This is the tree 'level' data */
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X509_POLICY_LEVEL *levels;
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int nlevel;
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@@ -159,7 +164,8 @@ X509_POLICY_NODE *tree_find_sk(STACK_OF(X509_POLICY_NODE) *sk,
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X509_POLICY_NODE *level_add_node(X509_POLICY_LEVEL *level,
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X509_POLICY_DATA *data,
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X509_POLICY_NODE *parent,
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- X509_POLICY_TREE *tree);
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+ X509_POLICY_TREE *tree,
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+ int extra_data);
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void policy_node_free(X509_POLICY_NODE *node);
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int policy_node_match(const X509_POLICY_LEVEL *lvl,
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const X509_POLICY_NODE *node, const ASN1_OBJECT *oid);
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diff --git a/crypto/x509v3/pcy_node.c b/crypto/x509v3/pcy_node.c
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index e2d7b15322..d574fb9d66 100644
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--- a/crypto/x509v3/pcy_node.c
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+++ b/crypto/x509v3/pcy_node.c
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@@ -59,10 +59,15 @@ X509_POLICY_NODE *level_find_node(const X509_POLICY_LEVEL *level,
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X509_POLICY_NODE *level_add_node(X509_POLICY_LEVEL *level,
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X509_POLICY_DATA *data,
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X509_POLICY_NODE *parent,
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- X509_POLICY_TREE *tree)
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+ X509_POLICY_TREE *tree,
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+ int extra_data)
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{
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X509_POLICY_NODE *node;
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+ /* Verify that the tree isn't too large. This mitigates CVE-2023-0464 */
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+ if (tree->node_maximum > 0 && tree->node_count >= tree->node_maximum)
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+ return NULL;
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+
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node = OPENSSL_zalloc(sizeof(*node));
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if (node == NULL) {
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X509V3err(X509V3_F_LEVEL_ADD_NODE, ERR_R_MALLOC_FAILURE);
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@@ -70,7 +75,7 @@ X509_POLICY_NODE *level_add_node(X509_POLICY_LEVEL *level,
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}
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node->data = data;
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node->parent = parent;
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- if (level) {
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+ if (level != NULL) {
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if (OBJ_obj2nid(data->valid_policy) == NID_any_policy) {
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if (level->anyPolicy)
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goto node_error;
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@@ -90,7 +95,7 @@ X509_POLICY_NODE *level_add_node(X509_POLICY_LEVEL *level,
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}
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}
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- if (tree) {
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+ if (extra_data) {
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if (tree->extra_data == NULL)
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tree->extra_data = sk_X509_POLICY_DATA_new_null();
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if (tree->extra_data == NULL){
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@@ -103,6 +108,7 @@ X509_POLICY_NODE *level_add_node(X509_POLICY_LEVEL *level,
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}
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}
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+ tree->node_count++;
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if (parent)
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parent->nchild++;
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diff --git a/crypto/x509v3/pcy_tree.c b/crypto/x509v3/pcy_tree.c
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index 6e8322cbc5..6c7fd35405 100644
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--- a/crypto/x509v3/pcy_tree.c
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+++ b/crypto/x509v3/pcy_tree.c
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@@ -13,6 +13,18 @@
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#include "pcy_local.h"
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+/*
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+ * If the maximum number of nodes in the policy tree isn't defined, set it to
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+ * a generous default of 1000 nodes.
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+ *
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+ * Defining this to be zero means unlimited policy tree growth which opens the
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+ * door on CVE-2023-0464.
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+ */
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+
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+#ifndef OPENSSL_POLICY_TREE_NODES_MAX
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+# define OPENSSL_POLICY_TREE_NODES_MAX 1000
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+#endif
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+
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/*
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* Enable this to print out the complete policy tree at various point during
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* evaluation.
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@@ -168,6 +180,9 @@ static int tree_init(X509_POLICY_TREE **ptree, STACK_OF(X509) *certs,
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return X509_PCY_TREE_INTERNAL;
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}
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+ /* Limit the growth of the tree to mitigate CVE-2023-0464 */
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+ tree->node_maximum = OPENSSL_POLICY_TREE_NODES_MAX;
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+
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/*
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* http://tools.ietf.org/html/rfc5280#section-6.1.2, figure 3.
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*
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@@ -184,7 +199,7 @@ static int tree_init(X509_POLICY_TREE **ptree, STACK_OF(X509) *certs,
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level = tree->levels;
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if ((data = policy_data_new(NULL, OBJ_nid2obj(NID_any_policy), 0)) == NULL)
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goto bad_tree;
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- if (level_add_node(level, data, NULL, tree) == NULL) {
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+ if (level_add_node(level, data, NULL, tree, 1) == NULL) {
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policy_data_free(data);
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goto bad_tree;
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}
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@@ -243,7 +258,8 @@ static int tree_init(X509_POLICY_TREE **ptree, STACK_OF(X509) *certs,
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* Return value: 1 on success, 0 otherwise
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*/
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static int tree_link_matching_nodes(X509_POLICY_LEVEL *curr,
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- X509_POLICY_DATA *data)
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+ X509_POLICY_DATA *data,
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+ X509_POLICY_TREE *tree)
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{
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X509_POLICY_LEVEL *last = curr - 1;
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int i, matched = 0;
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@@ -253,13 +269,13 @@ static int tree_link_matching_nodes(X509_POLICY_LEVEL *curr,
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X509_POLICY_NODE *node = sk_X509_POLICY_NODE_value(last->nodes, i);
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if (policy_node_match(last, node, data->valid_policy)) {
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- if (level_add_node(curr, data, node, NULL) == NULL)
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+ if (level_add_node(curr, data, node, tree, 0) == NULL)
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return 0;
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matched = 1;
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}
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}
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if (!matched && last->anyPolicy) {
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- if (level_add_node(curr, data, last->anyPolicy, NULL) == NULL)
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+ if (level_add_node(curr, data, last->anyPolicy, tree, 0) == NULL)
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return 0;
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}
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return 1;
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@@ -272,7 +288,8 @@ static int tree_link_matching_nodes(X509_POLICY_LEVEL *curr,
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* Return value: 1 on success, 0 otherwise.
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*/
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static int tree_link_nodes(X509_POLICY_LEVEL *curr,
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- const X509_POLICY_CACHE *cache)
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+ const X509_POLICY_CACHE *cache,
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+ X509_POLICY_TREE *tree)
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{
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int i;
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@@ -280,7 +297,7 @@ static int tree_link_nodes(X509_POLICY_LEVEL *curr,
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X509_POLICY_DATA *data = sk_X509_POLICY_DATA_value(cache->data, i);
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/* Look for matching nodes in previous level */
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- if (!tree_link_matching_nodes(curr, data))
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+ if (!tree_link_matching_nodes(curr, data, tree))
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return 0;
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}
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return 1;
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@@ -311,7 +328,7 @@ static int tree_add_unmatched(X509_POLICY_LEVEL *curr,
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/* Curr may not have anyPolicy */
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data->qualifier_set = cache->anyPolicy->qualifier_set;
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data->flags |= POLICY_DATA_FLAG_SHARED_QUALIFIERS;
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- if (level_add_node(curr, data, node, tree) == NULL) {
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+ if (level_add_node(curr, data, node, tree, 1) == NULL) {
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policy_data_free(data);
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return 0;
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}
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@@ -373,7 +390,7 @@ static int tree_link_any(X509_POLICY_LEVEL *curr,
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}
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/* Finally add link to anyPolicy */
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if (last->anyPolicy &&
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- level_add_node(curr, cache->anyPolicy, last->anyPolicy, NULL) == NULL)
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+ level_add_node(curr, cache->anyPolicy, last->anyPolicy, tree, 0) == NULL)
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return 0;
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return 1;
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}
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@@ -555,7 +572,7 @@ static int tree_calculate_user_set(X509_POLICY_TREE *tree,
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extra->qualifier_set = anyPolicy->data->qualifier_set;
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extra->flags = POLICY_DATA_FLAG_SHARED_QUALIFIERS
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| POLICY_DATA_FLAG_EXTRA_NODE;
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- node = level_add_node(NULL, extra, anyPolicy->parent, tree);
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+ node = level_add_node(NULL, extra, anyPolicy->parent, tree, 1);
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}
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if (!tree->user_policies) {
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tree->user_policies = sk_X509_POLICY_NODE_new_null();
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@@ -582,7 +599,7 @@ static int tree_evaluate(X509_POLICY_TREE *tree)
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for (i = 1; i < tree->nlevel; i++, curr++) {
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cache = policy_cache_set(curr->cert);
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- if (!tree_link_nodes(curr, cache))
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+ if (!tree_link_nodes(curr, cache, tree))
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return X509_PCY_TREE_INTERNAL;
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if (!(curr->flags & X509_V_FLAG_INHIBIT_ANY)
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--
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2.34.1
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