From 22794132513e7c8ddc3cff98f7786a48554499dc Mon Sep 17 00:00:00 2001 From: Isaac Boukris Date: Sat, 18 Aug 2018 00:40:30 +0300 Subject: [PATCH] CVE-2018-16853: The ticket in check_policy_as can actually be a TGS This happens when we are called from S4U2Self flow, and in that case kdcreq->client is NULL. Use the name from client entry instead. BUG: https://bugzilla.samba.org/show_bug.cgi?id=13571 Signed-off-by: Isaac Boukris Reviewed-by: Andreas Schneider Reviewed-by: Stefan Metzmacher --- source4/kdc/mit-kdb/kdb_samba_policies.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) diff --git a/source4/kdc/mit-kdb/kdb_samba_policies.c b/source4/kdc/mit-kdb/kdb_samba_policies.c index 81140abfd50..4364461302c 100644 --- a/source4/kdc/mit-kdb/kdb_samba_policies.c +++ b/source4/kdc/mit-kdb/kdb_samba_policies.c @@ -81,6 +81,7 @@ krb5_error_code kdb_samba_db_check_policy_as(krb5_context context, char *netbios_name = NULL; char *realm = NULL; bool password_change = false; + krb5_const_principal client_princ; DATA_BLOB int_data = { NULL, 0 }; krb5_data d; krb5_pa_data **e_data; @@ -90,7 +91,10 @@ krb5_error_code kdb_samba_db_check_policy_as(krb5_context context, return KRB5_KDB_DBNOTINITED; } - if (ks_is_kadmin(context, kdcreq->client)) { + /* Prefer canonicalised name from client entry */ + client_princ = client ? client->princ : kdcreq->client; + + if (client_princ == NULL || ks_is_kadmin(context, client_princ)) { return KRB5KDC_ERR_C_PRINCIPAL_UNKNOWN; } @@ -111,7 +115,7 @@ krb5_error_code kdb_samba_db_check_policy_as(krb5_context context, goto done; } - code = krb5_unparse_name(context, kdcreq->client, &client_name); + code = krb5_unparse_name(context, client_princ, &client_name); if (code) { goto done; } -- 2.47.2