Reported to Heimdal by Michał Kępień <michal@isc.org>.
From the report:
Acknowledgement
---------------
This flaw was found while working on addressing ZDI-CAN-12302: ISC BIND
TKEY Query Heap-based Buffer Overflow Remote Code Execution
Vulnerability, which was reported to ISC by Trend Micro's Zero Day
Initiative.
Fix for issue #486 based on a patch by Nico Williams.
A GSS-API acceptor can return an error token to be sent to the initiator. Our
SPNEGO implementation discarded these when sending a SPNEGO reject response.
This patch fixes the SPNEGO acceptor to convey those in the SPNEGO response.
The SPNEGO initiator is also updated to not bail out early on receiving a
SPNEGO reject response from the acceptor, but instead pass the response token
(if any) to gss_init_sec_context(). A reject response with no response token
will continue to return an error.
SPNEGO was already using union creds. Now make the mechglue know about
it, delete all of the cred-related SPNEGO stubs that are now not called
(lib/gssapi/spnego/cred_stubs.c), and implement gss_get/set_neg_mechs()
by storing the OID set in the union cred.
This commit was essentially authored as much if not more by Luke Howard
<lukeh at padl.com> as much as by the listed author.
Sort the list of mechanisms proposed by the initiator so that mechanisms are
preferred by their advertised support for GSS flags. For example, if
GSS_C_MUTUAL_FLAG is requested, a mechanism that offers GSS_C_MA_AUTH_TARG will
be preferred over one that doesn't. The flag/mechanism attribute combinations
are also assigned a weight (mutual trumps anonymous, for example).
RFC 4178 4.2.2 uses the field name negState rather than negResult in
NegTokenResp, to denote the negotiation state. Harmonize with this, also
replacing the underscores in accept-completed and accepet-incomplete to match
the RFC.
An implementation of draft-zhu-negoex-04 for MIT Kerberos was developed in
2011. This has been recently integrated, with many fixes from Greg Hudson. This
commit ports it to Heimdal. The implementation has been interoperability tested
with MIT Kerberos and Windows, using the GSS EAP mechanism developed as part of
the Moonshot project.
The SPNEGO code was also updated to import the state machine from Apple which
improves mechListMIC processing and avoids discarding initial context tokens
generated during mechanism probing, that can be used for optimistic tokens.
Finally, to aid in testing, the GSS-API mechanism glue configuration file can
be changed using the environment variable GSS_MECH_CONFIG. This environment
variable name, along with the format of the configuration file, is compatible
with MIT (although it would be difficult for a single mechanism binary to
support both implementations).
Wrapping GSS names at the SPNEGO level serves no purpose; remove it and return
mechglue names directly. This required a small change to the NTLM mechanism to
allow NULL names to be passed to its release name function.
SPNEGO uses the callback function acceptor_approved() in order to determine
which mechanisms to advertise to the initiator in the case that the initiator
sent an empty initial context token. Prior to this commit, that function was
not passed in the acceptor credential (if present), so always uses a default
credential. For correctness, we should only advertise the availability of
mechanisms for which we have a credential.
SPNEGO uses the callback function initiator_approved() in order to determine
mechanism availability. Prior to this commit, is not passed in the initiator
credential, so it always uses a default credential. This breaks SPNEGO if a
non-default credential (such as one acquired with
gss_acquire_cred_with_password()) is used. This commit addresses this.
most of these warnings are not problems because of ample
use of abort() calls. However, the large number of warnings
makes it difficult to identify real problems. Initialize
the variables to shut up the compilers.
Change-Id: I8477c11b17c7b6a7d9074c721fdd2d7303b186a8
of guessing the acceptor name and do gss_acquire_cred, this make
SPNEGO work like before.
git-svn-id: svn://svn.h5l.se/heimdal/trunk/heimdal@19435 ec53bebd-3082-4978-b11e-865c3cabbd6b
