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security/openssl: Security update for CVE-2023-0464
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From 879f7080d7e141f415c79eaa3a8ac4a3dad0348b Mon Sep 17 00:00:00 2001 | ||
From: 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) | ||
--- | ||
crypto/x509v3/pcy_local.h | 8 +++++++- | ||
crypto/x509v3/pcy_node.c | 12 +++++++++--- | ||
crypto/x509v3/pcy_tree.c | 37 +++++++++++++++++++++++++++---------- | ||
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 | ||
index 5daf78de4585..344aa067659c 100644 | ||
--- crypto/x509v3/pcy_local.h.orig | ||
+++ crypto/x509v3/pcy_local.h | ||
@@ -111,6 +111,11 @@ struct X509_POLICY_LEVEL_st { | ||
}; | ||
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||
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; | ||
@@ -159,7 +164,8 @@ X509_POLICY_NODE *tree_find_sk(STACK_OF(X509_POLICY_NODE) *sk, | ||
X509_POLICY_NODE *level_add_node(X509_POLICY_LEVEL *level, | ||
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/crypto/x509v3/pcy_node.c b/crypto/x509v3/pcy_node.c | ||
index e2d7b1532236..d574fb9d665d 100644 | ||
--- crypto/x509v3/pcy_node.c.orig | ||
+++ crypto/x509v3/pcy_node.c | ||
@@ -59,10 +59,15 @@ X509_POLICY_NODE *level_find_node(const X509_POLICY_LEVEL *level, | ||
X509_POLICY_NODE *level_add_node(X509_POLICY_LEVEL *level, | ||
X509_POLICY_DATA *data, | ||
X509_POLICY_NODE *parent, | ||
- X509_POLICY_TREE *tree) | ||
+ X509_POLICY_TREE *tree, | ||
+ int extra_data) | ||
{ | ||
X509_POLICY_NODE *node; | ||
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+ /* 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_zalloc(sizeof(*node)); | ||
if (node == NULL) { | ||
X509V3err(X509V3_F_LEVEL_ADD_NODE, ERR_R_MALLOC_FAILURE); | ||
@@ -70,7 +75,7 @@ X509_POLICY_NODE *level_add_node(X509_POLICY_LEVEL *level, | ||
} | ||
node->data = data; | ||
node->parent = parent; | ||
- if (level) { | ||
+ if (level != NULL) { | ||
if (OBJ_obj2nid(data->valid_policy) == NID_any_policy) { | ||
if (level->anyPolicy) | ||
goto node_error; | ||
@@ -90,7 +95,7 @@ X509_POLICY_NODE *level_add_node(X509_POLICY_LEVEL *level, | ||
} | ||
} | ||
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- if (tree) { | ||
+ if (extra_data) { | ||
if (tree->extra_data == NULL) | ||
tree->extra_data = sk_X509_POLICY_DATA_new_null(); | ||
if (tree->extra_data == NULL){ | ||
@@ -103,6 +108,7 @@ X509_POLICY_NODE *level_add_node(X509_POLICY_LEVEL *level, | ||
} | ||
} | ||
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+ tree->node_count++; | ||
if (parent) | ||
parent->nchild++; | ||
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diff --git a/crypto/x509v3/pcy_tree.c b/crypto/x509v3/pcy_tree.c | ||
index 6e8322cbc5e3..6c7fd3540500 100644 | ||
--- crypto/x509v3/pcy_tree.c.orig | ||
+++ crypto/x509v3/pcy_tree.c | ||
@@ -13,6 +13,18 @@ | ||
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#include "pcy_local.h" | ||
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+/* | ||
+ * 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 | ||
+ | ||
/* | ||
* Enable this to print out the complete policy tree at various point during | ||
* evaluation. | ||
@@ -168,6 +180,9 @@ static int tree_init(X509_POLICY_TREE **ptree, STACK_OF(X509) *certs, | ||
return X509_PCY_TREE_INTERNAL; | ||
} | ||
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+ /* 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. | ||
* | ||
@@ -184,7 +199,7 @@ static int tree_init(X509_POLICY_TREE **ptree, STACK_OF(X509) *certs, | ||
level = tree->levels; | ||
if ((data = policy_data_new(NULL, OBJ_nid2obj(NID_any_policy), 0)) == NULL) | ||
goto bad_tree; | ||
- if (level_add_node(level, data, NULL, tree) == NULL) { | ||
+ if (level_add_node(level, data, NULL, tree, 1) == NULL) { | ||
policy_data_free(data); | ||
goto bad_tree; | ||
} | ||
@@ -243,7 +258,8 @@ static int tree_init(X509_POLICY_TREE **ptree, STACK_OF(X509) *certs, | ||
* Return value: 1 on success, 0 otherwise | ||
*/ | ||
static int tree_link_matching_nodes(X509_POLICY_LEVEL *curr, | ||
- X509_POLICY_DATA *data) | ||
+ X509_POLICY_DATA *data, | ||
+ X509_POLICY_TREE *tree) | ||
{ | ||
X509_POLICY_LEVEL *last = curr - 1; | ||
int i, matched = 0; | ||
@@ -253,13 +269,13 @@ static int tree_link_matching_nodes(X509_POLICY_LEVEL *curr, | ||
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)) { | ||
- if (level_add_node(curr, data, node, NULL) == NULL) | ||
+ if (level_add_node(curr, data, node, tree, 0) == NULL) | ||
return 0; | ||
matched = 1; | ||
} | ||
} | ||
if (!matched && last->anyPolicy) { | ||
- if (level_add_node(curr, data, last->anyPolicy, NULL) == NULL) | ||
+ if (level_add_node(curr, data, last->anyPolicy, tree, 0) == NULL) | ||
return 0; | ||
} | ||
return 1; | ||
@@ -272,7 +288,8 @@ static int tree_link_matching_nodes(X509_POLICY_LEVEL *curr, | ||
* Return value: 1 on success, 0 otherwise. | ||
*/ | ||
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; | ||
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@@ -280,7 +297,7 @@ static int tree_link_nodes(X509_POLICY_LEVEL *curr, | ||
X509_POLICY_DATA *data = sk_X509_POLICY_DATA_value(cache->data, i); | ||
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/* 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; | ||
@@ -311,7 +328,7 @@ 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) == NULL) { | ||
+ if (level_add_node(curr, data, node, tree, 1) == NULL) { | ||
policy_data_free(data); | ||
return 0; | ||
} | ||
@@ -373,7 +390,7 @@ static int tree_link_any(X509_POLICY_LEVEL *curr, | ||
} | ||
/* Finally add link to anyPolicy */ | ||
if (last->anyPolicy && | ||
- level_add_node(curr, cache->anyPolicy, last->anyPolicy, NULL) == NULL) | ||
+ level_add_node(curr, cache->anyPolicy, last->anyPolicy, tree, 0) == NULL) | ||
return 0; | ||
return 1; | ||
} | ||
@@ -555,7 +572,7 @@ 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(); | ||
@@ -582,7 +599,7 @@ static int tree_evaluate(X509_POLICY_TREE *tree) | ||
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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 X509_PCY_TREE_INTERNAL; | ||
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if (!(curr->flags & X509_V_FLAG_INHIBIT_ANY) |