Improve bad password inference in kinit

kinit currently outputs "Password incorrect" if it sees a
bad-integrity error code, which results if the KDC reply couldn't be
decrypted, or when encrypted timestamp preauth fails against an MIT
krb5 1.14 or earlier KDC.  Expand this check to include general
preauth failures reported by the KDC, but only if a password was
prompted for.

ticket: 8465 (new)

1 files changed, 20 insertions, 6 deletions

diff --git a/src/clients/kinit/kinit.c b/src/clients/kinit/kinit.c
index f24c319..ce5aa4b 100644
--- a/src/clients/kinit/kinit.c
+++ b/src/clients/kinit/kinit.c
@@ -684,9 +684,18 @@ kinit_prompter(
     krb5_prompt prompts[]
 )
 {
-    krb5_error_code rc =
-        krb5_prompter_posix(ctx, data, name, banner, num_prompts, prompts);
-    return rc;
+    krb5_boolean *pwprompt = data;
+    krb5_prompt_type *ptypes;
+    int i;
+
+    /* Make a note if we receive a password prompt. */
+    ptypes = krb5_get_prompt_types(ctx);
+    for (i = 0; i < num_prompts; i++) {
+        if (ptypes != NULL && ptypes[i] == KRB5_PROMPT_TYPE_PASSWORD)
+            *pwprompt = TRUE;
+    }
+
+    return krb5_prompter_posix(ctx, data, name, banner, num_prompts, prompts);
 }
 
 static int
@@ -699,6 +708,7 @@ k5_kinit(opts, k5)
     krb5_creds my_creds;
     krb5_error_code code = 0;
     krb5_get_init_creds_opt *options = NULL;
+    krb5_boolean pwprompt = FALSE;
     int i;
 
     memset(&my_creds, 0, sizeof(my_creds));
@@ -807,7 +817,7 @@ k5_kinit(opts, k5)
     switch (opts->action) {
     case INIT_PW:
         code = krb5_get_init_creds_password(k5->ctx, &my_creds, k5->me,
-                                            0, kinit_prompter, 0,
+                                            0, kinit_prompter, &pwprompt,
                                             opts->starttime,
                                             opts->service_name,
                                             options);
@@ -844,11 +854,15 @@ k5_kinit(opts, k5)
             break;
         }
 
-        if (code == KRB5KRB_AP_ERR_BAD_INTEGRITY)
+        /* If reply decryption failed, or if pre-authentication failed and we
+         * were prompted for a password, assume the password was wrong. */
+        if (code == KRB5KRB_AP_ERR_BAD_INTEGRITY ||
+            (pwprompt && code == KRB5KDC_ERR_PREAUTH_FAILED)) {
             fprintf(stderr, _("%s: Password incorrect while %s\n"), progname,
                     doing);
-        else
+        } else {
             com_err(progname, code, _("while %s"), doing);
+        }
         goto cleanup;
     }