KRB5: Do not attempt to get a TGT after a password change using OTP

https://fedorahosted.org/sssd/ticket/2271

The current krb5_child code attempts to get a TGT for the convenience of
the user using the new password after a password change operation.
However, an OTP should never be used twice, which means we can't perform
the kinit operation after chpass is finished. Instead, we only print a
PAM information instructing the user to log out and back in manually.

Reviewed-by: Alexander Bokovoy <abokovoy@redhat.com>

1 files changed, 12 insertions, 0 deletions

diff --git a/src/providers/krb5/krb5_child.c b/src/providers/krb5/krb5_child.c
index d000d7016..3ee49e467 100644
--- a/src/providers/krb5/krb5_child.c
+++ b/src/providers/krb5/krb5_child.c
@@ -45,6 +45,7 @@ struct krb5_req {
     krb5_principal princ;
     char* name;
     krb5_creds *creds;
+    bool otp;
     krb5_get_init_creds_opt *options;
 
     struct pam_data *pd;
@@ -370,6 +371,8 @@ static krb5_error_code answer_otp(krb5_context ctx,
         goto done;
     }
 
+    kr->otp = true;
+
     /* Validate our assumptions about the contents of authtok. */
     ret = sss_authtok_get_password(kr->pd->authtok, &pwd, &len);
     if (ret != EOK)
@@ -694,6 +697,8 @@ static errno_t k5c_send_data(struct krb5_req *kr, int fd, errno_t error)
     size_t len;
     int ret;
 
+    DEBUG(SSSDBG_FUNC_DATA, ("Received error code %d\n", error));
+
     ret = pack_response_packet(kr, error, kr->pd->resp_list, &buf, &len);
     if (ret != EOK) {
         DEBUG(1, ("pack_response_packet failed.\n"));
@@ -1110,6 +1115,8 @@ static errno_t changepw_child(struct krb5_req *kr, bool prelim)
                                         prompter, kr, 0,
                                         SSSD_KRB5_CHANGEPW_PRINCIPAL,
                                         kr->options);
+    DEBUG(SSSDBG_TRACE_INTERNAL,
+          ("chpass is%s using OTP\n", kr->otp ? "" : " not"));
     if (kerr != 0) {
         ret = pack_user_info_chpass_error(kr->pd, "Old password not accepted.",
                                           &msg_len, &msg);
@@ -1205,6 +1212,11 @@ static errno_t changepw_child(struct krb5_req *kr, bool prelim)
 
     krb5_free_cred_contents(kr->ctx, kr->creds);
 
+    if (kr->otp == true) {
+        sss_authtok_set_empty(kr->pd->newauthtok);
+        return map_krb5_error(kerr);
+    }
+
     /* We changed some of the gic options for the password change, now we have
      * to change them back to get a fresh TGT. */
     revert_changepw_options(kr->options);