From ed19b0008b5802505a6ccb05e5bac05baf90c418 Mon Sep 17 00:00:00 2001
rom: Pauli <pauli@openssl.org>
Date: Wed, 8 Mar 2023 15:28:20 +1100
Subject: [PATCH] x509: excessive resource use verifying policy
constraints

A security vulnerability has been identified in all supported versions
of OpenSSL related to the verification of X.509 certificate chains
that include policy constraints.  Attackers may be able to exploit this
vulnerability by creating a malicious certificate chain that triggers
exponential use of computational resources, leading to a
denial-of-service
(DoS) attack on affected systems.

Fixes CVE-2023-0464

Reviewed-by: Tomas Mraz <tomas@openssl.org>
Reviewed-by: Shane Lontis <shane.lontis@oracle.com>
(Merged from https://github.com/openssl/openssl/pull/20569)

---
 Cryptlib/OpenSSL/crypto/x509v3/pcy_int.h  |  8 +++++-
 Cryptlib/OpenSSL/crypto/x509v3/pcy_node.c | 11 +++++++--
 Cryptlib/OpenSSL/crypto/x509v3/pcy_tree.c | 30 ++++++++++++++---------
 3 files changed, 35 insertions(+), 14 deletions(-)

diff --git a/Cryptlib/OpenSSL/crypto/x509v3/pcy_int.h b/Cryptlib/OpenSSL/crypto/x509v3/pcy_int.h
index b5075f9..0ed2349 100644
--- a/Cryptlib/OpenSSL/crypto/x509v3/pcy_int.h
+++ b/Cryptlib/OpenSSL/crypto/x509v3/pcy_int.h
@@ -161,6 +161,11 @@ struct X509_POLICY_LEVEL_st {
 };
 
 struct X509_POLICY_TREE_st {
+    /* The number of nodes in the tree */
+    size_t node_count;
+    /* The maximum number of nodes in the tree */
+    size_t node_maximum;
+
     /* This is the tree 'level' data */
     X509_POLICY_LEVEL *levels;
     int nlevel;
@@ -209,7 +214,8 @@ X509_POLICY_NODE *tree_find_sk(STACK_OF(X509_POLICY_NODE) *sk,
 X509_POLICY_NODE *level_add_node(X509_POLICY_LEVEL *level,
                                  const X509_POLICY_DATA *data,
                                  X509_POLICY_NODE *parent,
-                                 X509_POLICY_TREE *tree);
+                                 X509_POLICY_TREE *tree,
+                                 int extra_data);
 void policy_node_free(X509_POLICY_NODE *node);
 int policy_node_match(const X509_POLICY_LEVEL *lvl,
                       const X509_POLICY_NODE *node, const ASN1_OBJECT *oid);
diff --git a/Cryptlib/OpenSSL/crypto/x509v3/pcy_node.c b/Cryptlib/OpenSSL/crypto/x509v3/pcy_node.c
index d6c9176..75b3791 100644
--- a/Cryptlib/OpenSSL/crypto/x509v3/pcy_node.c
+++ b/Cryptlib/OpenSSL/crypto/x509v3/pcy_node.c
@@ -111,9 +111,15 @@ X509_POLICY_NODE *level_find_node(const X509_POLICY_LEVEL *level,
 X509_POLICY_NODE *level_add_node(X509_POLICY_LEVEL *level,
                                  const X509_POLICY_DATA *data,
                                  X509_POLICY_NODE *parent,
-                                 X509_POLICY_TREE *tree)
+                                 X509_POLICY_TREE *tree,
+                                 int extra_data)
 {
     X509_POLICY_NODE *node;
+
+    /* Verify that the tree isn't too large. this mitigates CVE-2023-0464 */
+    if (tree->node_maximum > 0 && tree->node_count >= tree->node_maximum)
+        return NULL;
+
     node = OPENSSL_malloc(sizeof(X509_POLICY_NODE));
     if (!node)
         return NULL;
@@ -136,7 +142,7 @@ X509_POLICY_NODE *level_add_node(X509_POLICY_LEVEL *level,
         }
     }
 
-    if (tree) {
+    if (extra_data) {
         if (!tree->extra_data)
             tree->extra_data = sk_X509_POLICY_DATA_new_null();
         if (!tree->extra_data)
@@ -145,6 +151,7 @@ X509_POLICY_NODE *level_add_node(X509_POLICY_LEVEL *level,
             goto node_error;
     }
 
+    tree->node_count++;
     if (parent)
         parent->nchild++;
 
diff --git a/Cryptlib/OpenSSL/crypto/x509v3/pcy_tree.c b/Cryptlib/OpenSSL/crypto/x509v3/pcy_tree.c
index 09b8691..fb9a616 100644
--- a/Cryptlib/OpenSSL/crypto/x509v3/pcy_tree.c
+++ b/Cryptlib/OpenSSL/crypto/x509v3/pcy_tree.c
@@ -63,6 +63,10 @@
 
 #include "pcy_int.h"
 
+#ifndef OPENSSL_POLICY_TREE_NODES_MAX
+# define OPENSSL_POLICY_TREE_NODES_MAX 1000
+#endif
+
 /*
  * Enable this to print out the complete policy tree at various point during
  * evaluation.
@@ -225,6 +229,8 @@ static int tree_init(X509_POLICY_TREE **ptree, STACK_OF(X509) *certs,
     if (!tree)
         return 0;
 
+    /* Limit the groeth of the tree to mitigate CVE-2023-0464 */
+    tree->node_maximum = OPENSSL_POLICY_TREE_NODES_MAX;
     tree->flags = 0;
     tree->levels = OPENSSL_malloc(sizeof(X509_POLICY_LEVEL) * n);
     tree->nlevel = 0;
@@ -247,7 +253,7 @@ static int tree_init(X509_POLICY_TREE **ptree, STACK_OF(X509) *certs,
 
     data = policy_data_new(NULL, OBJ_nid2obj(NID_any_policy), 0);
 
-    if (!data || !level_add_node(level, data, NULL, tree))
+    if (!data || !level_add_node(level, data, NULL, tree, 1))
         goto bad_tree;
 
     for (i = n - 2; i >= 0; i--) {
@@ -304,7 +310,8 @@ static int tree_init(X509_POLICY_TREE **ptree, STACK_OF(X509) *certs,
 }
 
 static int tree_link_matching_nodes(X509_POLICY_LEVEL *curr,
-                                    const X509_POLICY_DATA *data)
+                                    const X509_POLICY_DATA *data,
+                                    X509_POLICY_TREE *tree)
 {
     X509_POLICY_LEVEL *last = curr - 1;
     X509_POLICY_NODE *node;
@@ -313,13 +320,13 @@ static int tree_link_matching_nodes(X509_POLICY_LEVEL *curr,
     for (i = 0; i < sk_X509_POLICY_NODE_num(last->nodes); i++) {
         node = sk_X509_POLICY_NODE_value(last->nodes, i);
         if (policy_node_match(last, node, data->valid_policy)) {
-            if (!level_add_node(curr, data, node, NULL))
+            if (!level_add_node(curr, data, node, tree, 0))
                 return 0;
             matched = 1;
         }
     }
     if (!matched && last->anyPolicy) {
-        if (!level_add_node(curr, data, last->anyPolicy, NULL))
+        if (!level_add_node(curr, data, last->anyPolicy, tree, 0))
             return 0;
     }
     return 1;
@@ -331,7 +338,8 @@ static int tree_link_matching_nodes(X509_POLICY_LEVEL *curr,
  */
 
 static int tree_link_nodes(X509_POLICY_LEVEL *curr,
-                           const X509_POLICY_CACHE *cache)
+                           const X509_POLICY_CACHE *cache,
+                           X509_POLICY_TREE *tree)
 {
     int i;
     X509_POLICY_DATA *data;
@@ -352,7 +360,7 @@ static int tree_link_nodes(X509_POLICY_LEVEL *curr,
             continue;
 #endif
         /* Look for matching nodes in previous level */
-        if (!tree_link_matching_nodes(curr, data))
+        if (!tree_link_matching_nodes(curr, data, tree))
             return 0;
     }
     return 1;
@@ -382,7 +390,7 @@ static int tree_add_unmatched(X509_POLICY_LEVEL *curr,
     /* Curr may not have anyPolicy */
     data->qualifier_set = cache->anyPolicy->qualifier_set;
     data->flags |= POLICY_DATA_FLAG_SHARED_QUALIFIERS;
-    if (!level_add_node(curr, data, node, tree)) {
+    if (!level_add_node(curr, data, node, tree, 1)) {
         policy_data_free(data);
         return 0;
     }
@@ -464,7 +472,7 @@ static int tree_link_any(X509_POLICY_LEVEL *curr,
         /* Curr may not have anyPolicy */
         data->qualifier_set = cache->anyPolicy->qualifier_set;
         data->flags |= POLICY_DATA_FLAG_SHARED_QUALIFIERS;
-        if (!level_add_node(curr, data, node, tree)) {
+        if (!level_add_node(curr, data, node, tree, 1)) {
             policy_data_free(data);
             return 0;
         }
@@ -473,7 +481,7 @@ static int tree_link_any(X509_POLICY_LEVEL *curr,
     }
     /* Finally add link to anyPolicy */
     if (last->anyPolicy) {
-        if (!level_add_node(curr, cache->anyPolicy, last->anyPolicy, NULL))
+        if (!level_add_node(curr, cache->anyPolicy, last->anyPolicy, tree, 0))
             return 0;
     }
     return 1;
@@ -646,7 +654,7 @@ static int tree_calculate_user_set(X509_POLICY_TREE *tree,
             extra->qualifier_set = anyPolicy->data->qualifier_set;
             extra->flags = POLICY_DATA_FLAG_SHARED_QUALIFIERS
                 | POLICY_DATA_FLAG_EXTRA_NODE;
-            node = level_add_node(NULL, extra, anyPolicy->parent, tree);
+            node = level_add_node(NULL, extra, anyPolicy->parent, tree, 1);
         }
         if (!tree->user_policies) {
             tree->user_policies = sk_X509_POLICY_NODE_new_null();
@@ -668,7 +676,7 @@ static int tree_evaluate(X509_POLICY_TREE *tree)
 
     for (i = 1; i < tree->nlevel; i++, curr++) {
         cache = policy_cache_set(curr->cert);
-        if (!tree_link_nodes(curr, cache))
+        if (!tree_link_nodes(curr, cache, tree))
             return 0;
 
         if (!(curr->flags & X509_V_FLAG_INHIBIT_ANY)
-- 
2.27.0

