The functions for storing and retrieving GSS OIDs and buffers from
krb5_storage, added in 6554dc69, are generally useful. Move those into private
_gss_mg_XXX() API and update gss_{export,import}_{cred,sec_context} to use them
where appropriate.
The recently introduced gss_mg_name_to_oid() function supported looking up
dynamically loaded mechanisms by name, but did not support partial matches or
the legacy "Kerberos 5" name as supported by gss_name_to_oid().
Consolidate these into a single function, and also add support for dynamically
loaded mechanisms to gss_oid_to_name().
API behavior difference: the Kerberos mechanism is now referred to by "krb5"
rather tha "Kerberos 5", although for legacy compatibility gss_name_to_oid()
will recognize the old name. However, gss_oid_to_name() will return "krb5". The
anticipated impact is minimal as these are not standard GSS-APIs and do not
appear to have any public usage outside Heimdal.
When using these functions with gss_init_sec_context(), we noticed
that some things were missing and some needed to be made optional.
ctx->order may be NULL, ctx->ac->authenticator needs to be filled
out, and ctx->state needs be stored.
Note: SPNEGO still needs a little more work.
To avoid future regressions such as the one corrected in 0dd19003, make
IS_DCE_STYLE() an inline function (rather than a macro) so that its
argument is typed.
4b543b7 introduced a regression in the krb5 mechanism's gss_unwrap for
DCE applications, owing to IS_DCE_STYLE() being called with a krb5
instead of mechanism context handle.
Some compilers with -Wstring-concatenation enabled warned about a suspicious
concatenation of string literals in the initialization of the GSS-API error
message array.
At the expense of a long line, avoid this warning but explicitly concatenating
the offending string literal.
Fixes: #775
acquire_cred_with_password() must call
krb5_get_init_creds_opt_set_default_flags() to initialize the
krb5_get_init_creds option flags to the values obtained from
the krb5_context.
Change-Id: Icd8c500dd0787a781c2382284f19cef277b1d30b
gss_unwrap_iov() with rc4-hmac (RFC4757) encryption types would fail unless
GSS_C_DCE_STYLE was specified, as an incorrect length was passed to
_gssapi_verify_mech_header(). (The correct length is the header length for
GSS_C_DCE_STYLE, and the wrap token length otherwise.)
RFC 4121/4757 don't require padding as they operate as stream ciphers. Make the
PADDING buffer optional when using these encryption types with gss_wrap_iov()
and gss_unwrap_iov().
Our initiator supports configuration-driven delegation of destination
TGTs.
This commit adds acceptor-side handling of destination TGT policy to
reject storing of non-destination TGTs when destination TGTs are
desired.
Currently we use the same appdefault for this.
Background:
A root TGT is one of the form krbtgt/REALM@SAME-REALM.
A destination TGT is a root TGT for the same realm as the acceptor
service's realm.
Normally clients delegate a root TGT for the client's realm.
In some deployments clients may want to delegate destination TGTs as
a form of constrained delegation: so that the destination service
cannot use the delegated credential to impersonate the client
principal to services in its home realm (due to KDC lineage/transit
checks). In those deployments there may not even be a route back to
the KDCs of the client's realm, and attempting to use a
non-destination TGT might even lead to timeouts.
_gsskrb5_init_sec_context() when called with GSS_C_NO_CREDENTIAL
opens the default ccache and sets the CLOSE_CCACHE flag indicating
that the ccache lifetime is tied to the gsskrb5_ctx. When
_gsskrb5_delete_sec_context() is called, it must close the ccache
if the CLOSE_CCACHE flag is set. Otherwise, the ccache resources
will leak.
Leaked since 39fe446983.
Change-Id: I8d0faab1e844d68fe71b11b715f8d88fcd2f4af7
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.
If an initial security context token doesn't have a standard header per
RFC2743 then try all mechanisms until one succeeds or all fail.
We still try to guess NTLMSSP, raw Kerberos, and SPNEGO, from tasting
the initial security context token.
Add a new private interface (accessed through _gss_mg_import_rfc4121_context())
through which a skeletal krb5 mechanism context can be created, suitable for
RFC4121 message protection and PRF services.
Allow the source and target names to be NULL when exporting or importing a
security context for the krb5 mechanism. This will be used in the future to
support skeletal contexts that only provide RFC4121 message protection
services.
The recent changes to SPNEGO removed support for GSS_C_PEER_HAS_UPDATED_SPNEGO,
through which the Kerberos mechanism could indicate to SPNEGO that the peer did
not suffer from SPNEGO conformance bugs present in some versions of Windows.*
This patch restores this workaround, documented in [MS-SPNG] Appendix A <7>
Section 3.1.5.1. Whilst improving interoperability with these admittedly now
unsupported versions of Windows, it does introduce a risk that Kerberos with
pre-AES ciphers could be negotiated in lieu of a stronger and more preferred
mechanism.
Note: this patch inverts the mechanism interface from
GSS_C_PEER_HAS_UPDATED_SPNEGO to GSS_C_INQ_PEER_HAS_BUGGY_SPNEGO, so that new
mechanisms (which did not ship with these older versions of Windows) are not
required to implement it.
* Windows 2000, Windows 2003, and Windows XP
Pending integration of #551, the krb5 mechanism does not support
GSS_C_ANON_FLAG. Remove the GSS_C_MA_AUTH_INIT_ANON mechanism attribute until
such time it does.
This is needed so that sshd and such can get make practical use of the
"ccache" key in GSS cred stores.
This commit only changes the store path, not the acquisition path.
gss_store_cred_into*() will now switch the new cred cache to be the
primary/default cred cache when
- the caller requested it and,
- if the caller passed in a user name, the creds' principal is the best
principal for the named user.
A principal is the best principal for a user when the principal has just
one component, the component is the user's username, and the realm is
the configured user_realm.
- Formalize the TYPE:collection_name:subsidiary_name naming scheme for
ccaches in ccache collections
- KEYRING: ccaches are weird because they have one more optional field: the
"anchor", so rather than just assume a naming convention everywhere, we
add new functions as well
- Add krb5_cc_{resolve,default}_sub() that allows one to specify a
"subsidiary" ccache name in a collection separately from the
collection name
- Add krb5_cc_{resolve,default}_for() which take a principal name,
unparse it, and use it as the subsidiary ccache name (with colons
replaced)
- Make kinit use the new interfaces
- Add missing DIR ccache iteration functionality
- Revamps test_cc
- Add krb5_cc_get_collection() and krb5_cc_get_subsidiary()
- Bump the ccops SPI version number
- Add gss_store_cred_into2()
- Make MEMORY:anonymous not linked into the global MEMORY ccache
collection, and uses this for delegated cred handles
TBD:
- Split this up into a krb5 change and gss mech_krb5 change?
- Add krb5_cc_init_and_store() utility, per Greg's suggestion?
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).
The Kerberos GSS mechanism specific error table in gkrb5_err.et was never
registered with libkrb5, so the messages corresponding to those errors would
never be available. Register them with the thread local context used by the
krb5 mechanism.
Refactor and enhance TGT forwarding to allow forwarding of leaf
(destination) TGTs for selected destination realms.
Enhance kinit(1) to renew non-origin realm tickets
Document delegate-destination-tgt
Use the newly implemented _krb5_mk_1cred().
krb5_cc_cache_match() searches all ccache collections for a ccache that
has credentials for a given principal name. This includes MEMORY
ccaches, which means it can find the same ccache as is referenced by a
GSS cred handle given to gss_store_cred(), which means that
gss_store_cred() can fail.
For now we work around this by including a private variant of
krb5_cc_cache_match() that only searches the default ccache, not all
collections. Eventually we should ensure that krb5_cc_default() also
searches all collection-type (other than MEMORY) ccaches for a default
credential, then we can go back to using krb5_cc_cache_match() (though
we'll need to make sure that MEMORY is searched last or not at all).
Implementation of gss_set_neg_mechs() and gss_get_neg_mechs() as defined in RFC
4178. New gss_release_cred_by_mech() API for dropping a credential from a
mechanism glue credential.
Implement the GSS-API credential store API extensions defined by MIT here:
https://k5wiki.kerberos.org/wiki/Projects/Credential_Store_extensions
Note: we kill off gss_acquire_cred_ext() here. This was never a public API,
although mechanisms could have implemented it and I briefly used it in my
BrowserID prototype mechanism. gss_acquire_cred_ext_from() occupies the place
in the dispatch table where gss_acquire_cred_ext() used to, but this structure
was never visible outside Heimdal (i.e. it is only used by internal
mechanisms);
(Mechanisms that need to accept arbitrary key/value dictionaries from
applications should now implement gss_acquire_cred_from().)
gss_krb5_set_allowable_enctypes() was declared with an array of int32_t types
representing the enctype list, but the definition had an array of krb5_enctype.
Whilst these are likely the same size, they may not be. On the receiving end,
allocate an array of krb5_enctype.
For compatibility with MIT Kerberos, support automatic acquisition of initiator
credentials if a client keytab is available. The default path on non-Windows is
/var/heimdal/user/%{euid}/client.keytab, but can be overriden with the
KRB5_CLIENT_KTNAME environment variable or the default_client_keytab_name
configuration option. If a client keytab does not exist, or exists but does not
contain the principal for which initiator credentials are being acquired, the
system keytab is tried.
It turns out gss_add_cred() really needed a complete rewrite. It's much
better to first have a gss_duplicate_cred() (which has been needed for
other reasons anyways), and use that when the input_cred_handle is not
GSS_C_NO_CREDENTIAL and output_cred_handle is not NULL, then mutate that
duplicate credential handle (or the input_cred_handle if
output_cred_handle is NULL).
Zero out the DES_cblock structure instead of the (not yet used at this point
in the function) key schedule. The contents could potentially be left
on the stack in the case of an error return from _gssapi_verify_pad().
