Extend -show_chain option to verify to show more info

The -show_chain flag to the verify command line app shows information about
the chain that has been built. This commit adds the text "untrusted" against
those certificates that have been used from the untrusted list.

Reviewed-by: Rich Salz <rsalz@openssl.org>

apps/verify.c

@@ -244,6 +244,7 @@ static int check(X509_STORE *ctx, char *file,
     int i = 0, ret = 0;
     X509_STORE_CTX *csc;
     STACK_OF(X509) *chain = NULL;
+    int num_untrusted;
 
     x = load_cert(file, FORMAT_PEM, NULL, e, "certificate file");
     if (x == NULL)
@@ -265,8 +266,10 @@ static int check(X509_STORE *ctx, char *file,
     if (crls)
         X509_STORE_CTX_set0_crls(csc, crls);
     i = X509_verify_cert(csc);
-    if (i > 0 && show_chain)
+    if (i > 0 && show_chain) {
         chain = X509_STORE_CTX_get1_chain(csc);
+        num_untrusted = X509_STORE_CTX_get_num_untrusted(csc);
+    }
     X509_STORE_CTX_free(csc);
 
     ret = 0;
@@ -284,6 +287,9 @@ static int check(X509_STORE *ctx, char *file,
             X509_NAME_print_ex_fp(stdout,
                                   X509_get_subject_name(cert),
                                   0, XN_FLAG_ONELINE);
+            if (i < num_untrusted) {
+                printf(" (untrusted)");
+            }
             printf("\n");
         }
         sk_X509_pop_free(chain, X509_free);

crypto/x509/x509_vfy.c

@@ -2452,6 +2452,11 @@ int X509_STORE_CTX_get_explicit_policy(X509_STORE_CTX *ctx)
     return ctx->explicit_policy;
 }
 
+int X509_STORE_CTX_get_num_untrusted(X509_STORE_CTX *ctx)
+{
+    return ctx->last_untrusted;
+}
+
 int X509_STORE_CTX_set_default(X509_STORE_CTX *ctx, const char *name)
 {
     const X509_VERIFY_PARAM *param;

doc/apps/verify.pod

@@ -42,6 +42,7 @@ B<openssl> B<verify>
 [B<-verify_ip ip>]
 [B<-verify_name name>]
 [B<-x509_strict>]
+[B<-show_chain>]
 [B<->]
 [certificates]
 
@@ -227,6 +228,12 @@ Supported usages include: default, pkcs7, smime_sign, ssl_client, ssl_server.
 For strict X.509 compliance, disable non-compliant workarounds for broken
 certificates.
 
+=item B<-show_chain>
+
+Display information about the certificate chain that has been built (if
+successful). Certificates in the chain that came from the untrusted list will be
+flagged as "untrusted".
+
 =item B<->
 
 Indicates the last option. All arguments following this are assumed to be
@@ -491,6 +498,6 @@ L<x509(1)|x509(1)>
 
 =head1 HISTORY
 
-The -no_alt_chains options was first added to OpenSSL 1.1.0.
+The -show_chain option was first added to OpenSSL 1.1.0.
 
 =cut

doc/crypto/X509_STORE_CTX_new.pod

@@ -25,6 +25,8 @@ X509_STORE_CTX_new, X509_STORE_CTX_cleanup, X509_STORE_CTX_free, X509_STORE_CTX_
  void X509_STORE_CTX_set0_param(X509_STORE_CTX *ctx, X509_VERIFY_PARAM *param);
  int X509_STORE_CTX_set_default(X509_STORE_CTX *ctx, const char *name);
 
+ int X509_STORE_CTX_get_num_untrusted(X509_STORE_CTX *ctx);
+
 =head1 DESCRIPTION
 
 These functions initialise an B<X509_STORE_CTX> structure for subsequent use
@@ -76,6 +78,9 @@ X509_STORE_CTX_set_default() looks up and sets the default verification
 method to B<name>. This uses the function X509_VERIFY_PARAM_lookup() to
 find an appropriate set of parameters from B<name>.
 
+X509_STORE_CTX_get_num_untrusted() returns the number of untrusted certificates
+that were used in building the chain following a call to X509_verify_cert().
+
 =head1 NOTES
 
 The certificates and CRLs in a store are used internally and should B<not>
@@ -116,6 +121,9 @@ values.
 
 X509_STORE_CTX_set_default() returns 1 for success or 0 if an error occurred.
 
+X509_STORE_CTX_get_num_untrusted() returns the number of untrusted certificates
+used.
+
 =head1 SEE ALSO
 
 L<X509_verify_cert(3)|X509_verify_cert(3)>
@@ -124,5 +132,6 @@ L<X509_VERIFY_PARAM_set_flags(3)|X509_VERIFY_PARAM_set_flags(3)>
 =head1 HISTORY
 
 X509_STORE_CTX_set0_crls() was first added to OpenSSL 1.0.0
+X509_STORE_CTX_get_num_untrusted() was first added to OpenSSL 1.1.0
 
 =cut

include/openssl/x509_vfy.h

@@ -528,6 +528,7 @@ void X509_STORE_CTX_set_verify_cb(X509_STORE_CTX *ctx,
 
 X509_POLICY_TREE *X509_STORE_CTX_get0_policy_tree(X509_STORE_CTX *ctx);
 int X509_STORE_CTX_get_explicit_policy(X509_STORE_CTX *ctx);
+int X509_STORE_CTX_get_num_untrusted(X509_STORE_CTX *ctx);
 
 X509_VERIFY_PARAM *X509_STORE_CTX_get0_param(X509_STORE_CTX *ctx);
 void X509_STORE_CTX_set0_param(X509_STORE_CTX *ctx, X509_VERIFY_PARAM *param);