krb5 commit: Fix interposed gss_accept_sec_context()

[Greg Hudson]

https://github.com/krb5/krb5/commit/0b43d10333f4c4b29896cebc9447d8866b661217
commit 0b43d10333f4c4b29896cebc9447d8866b661217
Author: Robbie Harwood <rharwood at redhat.com>
Date:   Wed Dec 16 19:31:22 2015 -0500

    Fix interposed gss_accept_sec_context()
    
    If gss_accept_sec_context() is interposed, selected_mech will be an
    interposer OID.  In this situation, pass the corresponding public OID
    to gss_inquire_attrs_for_mech() to determine whether the mech is
    allowed by default.
    
    [ghudson at mit.edu: pared down from larger commit; rewrote commit message]
    
    ticket: 8338 (new)
    target_version: 1.14-next
    tags: pullup

 src/lib/gssapi/mechglue/g_accept_sec_context.c |    6 ++++++
 1 files changed, 6 insertions(+), 0 deletions(-)

diff --git a/src/lib/gssapi/mechglue/g_accept_sec_context.c b/src/lib/gssapi/mechglue/g_accept_sec_context.c
index 6c72d1f..ddaf874 100644
--- a/src/lib/gssapi/mechglue/g_accept_sec_context.c
+++ b/src/lib/gssapi/mechglue/g_accept_sec_context.c
@@ -94,6 +94,12 @@ allow_mech_by_default(gss_OID mech)
     gss_OID_set attrs;
     int reject = 0, p;
 
+    /* Whether we accept an interposer mech depends on whether we accept the
+     * mech it interposes. */
+    mech = gssint_get_public_oid(mech);
+    if (mech == GSS_C_NO_OID)
+	return 0;
+
     status = gss_inquire_attrs_for_mech(&minor, mech, &attrs, NULL);
     if (status)
 	return 0;