1 files changed, 46 insertions, 3 deletions

diff --git a/src/lib/libcrypto/x509/x509_vfy.c b/src/lib/libcrypto/x509/x509_vfy.c
index fb87877e72..11bf3d9292 100644
--- a/src/lib/libcrypto/x509/x509_vfy.c
+++ b/src/lib/libcrypto/x509/x509_vfy.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: x509_vfy.c,v 1.103 2022/08/31 07:15:31 tb Exp $ */
+/* $OpenBSD: x509_vfy.c,v 1.104 2022/11/13 18:37:32 beck Exp $ */
 /* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
  * All rights reserved.
  *
@@ -724,6 +724,43 @@ get_issuer_sk(X509 **issuer, X509_STORE_CTX *ctx, X509 *x)
                 return 0;
 }
 
+/*
+ * X509_check_purpose is special.
+ * 0 is bad, 1 is good, values > 1 are maybe good for web pki necromancy
+ * and certificates that were checked into software unit tests years ago
+ * that nobody knows how to change. (Netscape Server Gated Crypto Forever!)
+ */
+#define PURPOSE_GOOD(x) (x == 1)
+#define PURPOSE_BAD(x) (x == 0)
+static int
+check_purpose(X509_STORE_CTX *ctx, X509 *x, int purpose, int depth,
+    int must_be_ca)
+{
+        int purpose_check, trust;
+
+        purpose_check = X509_check_purpose(x, purpose, must_be_ca > 0);
+        trust = X509_TRUST_UNTRUSTED;
+
+        /*
+         * For trusted certificates we want to see whether any auxiliary trust
+         * settings for the desired purpose override the purpose constraints
+         * from the certificate EKU.
+         */
+        if (depth >= ctx->num_untrusted && purpose == ctx->param->purpose)
+                trust = x509_check_trust_no_compat(x, ctx->param->trust, 0);
+
+        /* XXX STRICT should really be the default */
+        if (trust != X509_TRUST_REJECTED && !PURPOSE_BAD(purpose_check)) {
+                return PURPOSE_GOOD(purpose_check) ||
+                    (ctx->param->flags & X509_V_FLAG_X509_STRICT) == 0;
+        }
+
+        ctx->error = X509_V_ERR_INVALID_PURPOSE;
+        ctx->error_depth = depth;
+        ctx->current_cert = x;
+        return ctx->verify_cb(0, ctx);
+}
+
 /* Check a certificate chains extensions for consistency
  * with the supplied purpose
  */
@@ -740,6 +777,7 @@ x509_vfy_check_chain_extensions(X509_STORE_CTX *ctx)
         int proxy_path_length = 0;
         int purpose;
         int allow_proxy_certs;
+        size_t chain_len;
 
         cb = ctx->verify_cb;
 
@@ -763,8 +801,8 @@ x509_vfy_check_chain_extensions(X509_STORE_CTX *ctx)
                 purpose = ctx->param->purpose;
         }
 
-        /* Check all untrusted certificates */
-        for (i = 0; i < ctx->num_untrusted; i++) {
+        chain_len = sk_X509_num(ctx->chain);
+        for (i = 0; i < chain_len; i++) {
                 int ret;
                 x = sk_X509_value(ctx->chain, i);
                 if (!(ctx->param->flags & X509_V_FLAG_IGNORE_CRITICAL) &&
@@ -818,6 +856,11 @@ x509_vfy_check_chain_extensions(X509_STORE_CTX *ctx)
                         if (!ok)
                                 goto end;
                 }
+                if (purpose > 0) {
+                        ok = check_purpose(ctx, x, purpose, i, must_be_ca);
+                        if (!ok)
+                                goto end;
+                }
                 if (ctx->param->purpose > 0) {
                         ret = X509_check_purpose(x, purpose, must_be_ca > 0);
                         if ((ret == 0) ||