Correctly implement gss_krb5_ccache_name() in terms of
gss_set_sec_context_option(GSS_KRB5_CCACHE_NAME_X). The previous implementation
was a NOOP.
Note: global ccache name should really be thread-specific rather than global.
Closes#803.
Add support for GSS-API pre-authentication to the KDC, using a simplified
variation of draft-perez-krb-wg-gss-preauth-02 that encodes GSS-API context
tokens directly in PADATA, and uses FX-COOKIE for state management.
More information on the protocol and implementation may be found in
lib/gssapi/preauth/README.md.
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.
This function became used outside the protection of
HAVE_DLOPEN (which Samba sets) with:
commit 5966c00701
Author: Luke Howard <lukeh@padl.com>
Date: Sun Aug 8 10:34:28 2021 +1000
gss: add gss_mg_name_to_oid internal API
Add a new function for future internal use, gss_mg_name_to_oid(), which takes
either a dot-separated OID or a "short" mechanism name (such as
"sanon-x25519"), and returns a mechanism OID.
Signed-off-by: Andrew Bartlett <abartlet@samba.org>
gss_{import,export}_sec_context did not work with partially accumulating
contexts, where the initial context token had not been completely accumulated,
Further, in gss_import_sec_context(), ctx->gc_input.value was not allocated to
a buffer sufficiently large to accumulate the target length.
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.
Add a new function for future internal use, gss_mg_name_to_oid(), which takes
either a dot-separated OID or a "short" mechanism name (such as
"sanon-x25519"), and returns a mechanism OID.
Microsoft will sometimes split GSS tokens when they exceed a certain
size in some protocols. This is specified in
[MS-SPNG]: Simple and Protected GSS-API Negotiation
Mechanism (SPNEGO) Extension
https://winprotocoldoc.blob.core.windows.net/productionwindowsarchives/MS-SPNG/%5bMS-SPNG%5d.pdf
sections 3.1.5.4 to 3.1.5.9.
We extend gss_accept_sec_context() to recognise partial tokens and
to accumulate the fragments until an entire token is available to
be processed. If the entire token is not yet available,
GSS_S_CONTINUE_NEEDED is returned with a zero length output token.
This is specified in RFC2744 page 25-26 to indicate that no reply
need be sent.
We include updates to the test framework to test split tokens when
using SPNEGO.
In acquire_mech_cred(), treat a credential store with no elements as equivalent
to GSS_C_NO_CRED_STORE, allowing a mechanism's gss_acquire_cred()
implementation to be called.
GM_USE_MG_NAME was not honored in the case where the mechanism emitted a name,
but the caller of gss_accept_sec_context() did not request it be returned. This
would result in m->gm_release_name() being called on the mechglue name, which
would crash either because that function pointer was NULL or because it would
have expected a mechanism name.
Samba compiles Heimdal internally without HAVE_DLOPEN to keep
to internally supplied mechanisms and plugins.
Samba compiles with strict warning flags and on Ubuntu 20.04
with gcc version 9.3.0 (Ubuntu 9.3.0-17ubuntu1~20.04) we see:
../../source4/heimdal/lib/gssapi/mech/gss_mech_switch.c: In function ‘_gss_load_mech’:
../../source4/heimdal/lib/gssapi/mech/gss_mech_switch.c:462:1: error: label ‘out’ defined but not used [-Werror=unused-label]
462 | out:
| ^~~
cc1: all warnings being treated as errors
Signed-off-by: Andrew Bartlett <abartlet@samba.org>
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
Status:
- And it works!
- We have an extensive test based on decoding a rich EK certficate.
This test exercises all of:
- decoding
- encoding with and without decoded open types
- copying of decoded values with decoded open types
- freeing of decoded values with decoded open types
Valgrind finds no memory errors.
- Added a manual page for the compiler.
- rfc2459.asn1 now has all three primary PKIX types that we care about
defined as in RFC5912, with IOS constraints and parameterization:
- `Extension` (embeds open type in an `OCTET STRING`)
- `OtherName` (embeds open type in an `ANY`-like type)
- `SingleAttribute` (embeds open type in an `ANY`-like type)
- `AttributeSet` (embeds open type in a `SET OF ANY`-like type)
All of these use OIDs as the open type type ID field, but integer
open type type ID fields are also supported (and needed, for
Kerberos).
That will cover every typed hole pattern in all our ASN.1 modules.
With this we'll be able to automatically and recursively decode
through all subject DN attributes even when the subject DN is a
directoryName SAN, and subjectDirectoryAttributes, and all
extensions, and all SANs, and all authorization-data elements, and
PA-data, and...
We're not really using `SingleAttribute` and `AttributeSet` yet
because various changes are needed in `lib/hx509` for that.
- `asn1_compile` builds and recognizes the subset of X.681/682/683 that
we need for, and now use in, rfc2459.asn1. It builds the necessary
AST, generates the correct C types, and generates templating for
object sets and open types!
- See READMEs for details.
- Codegen backend not tested; I won't make it implement automatic open
type handling, but it should at least not crash by substituting
`heim_any` for open types not embedded in `OCTET STRING`.
- We're _really_ starting to have problems with the ITU-T ASN.1
grammar and our version of it...
Type names have to start with upper-case, value names with
lower-case, but it's not enough to disambiguate.
The fact the we've allowed value and type names to violate their
respective start-with case rules is causing us trouble now that we're
adding grammar from X.681/682/683, and we're going to have to undo
that.
In preparation for that I'm capitalizing the `heim_any` and
`heim_any_set` types, and doing some additional cleanup, which
requires changes to other parts of Heimdal (all in this same commit
for now).
Problems we have because of this:
- We cannot IMPORT values into modules because we have no idea if a
symbol being imported refers to a value or a type because the only
clue we would have is the symbol's name, so we assume IMPORTed
symbols are for types.
This means we can't import OIDs, for example, which is super
annoying.
One thing we might be able to do here is mark imported symbols as
being of an undetermined-but-not-undefined type, then coerce the
symbol's type the first time it's used in a context where its type
is inferred as type, value, object, object set, or class. (Though
since we don't generate C symbols for objects or classes, we won't
be able to import them, especially since we need to know them at
compile time and cannot defer their handling to link- or
run-time.)
- The `NULL` type name, and the `NULL` value name now cause two
reduce/reduce conflicts via the `FieldSetting` production.
- Various shift/reduce conflicts involving `NULL` values in
non-top-level contexts (in constraints, for example).
- Currently I have a bug where to disambiguate the grammar I have a
CLASS_IDENTIFIER token that is all caps, while TYPE_IDENTIFIER must
start with a capital but not be all caps, but this breaks Kerberos
since all its types are all capitalized -- oof!
To fix this I made it so class names have to be all caps and
start with an underscore (ick).
TBD:
- Check all the XXX comments and address them
- Apply this treatment to Kerberos! Automatic handling of authz-data
sounds useful :)
- Apply this treatment to PKCS#10 (CSRs) and other ASN.1 modules too.
- Replace various bits of code in `lib/hx509/` with uses of this
feature.
- Add JER.
- Enhance `hxtool` and `asn1_print`.
Getting there!
Seen with Ubuntu 18.04
gcc version 7.5.0 (Ubuntu 7.5.0-3ubuntu1~18.04)
mech/gss_krb5.c: In function ‘gss_krb5_ccache_name’:
mech/gss_krb5.c:501:18: error: the address of ‘buffer’ will always evaluate as ‘true’ [-Werror=address]
_mg_buffer_zero(&buffer);
^
mech/mech_locl.h:72:7: note: in definition of macro ‘_mg_buffer_zero’
if (buffer) { \
^~~~~~
Signed-off-by: Andrew Bartlett <abartlet@samba.org>
This avoids these compiler warnings on Ubuntu 18.04
gcc version 7.5.0 (Ubuntu 7.5.0-3ubuntu1~18.04)
expand_path.c: In function ‘expand_token’:
expand_path.c:493:17: warning: ignoring return value of ‘asprintf’, declared with attribute warn_unused_result [-Wunused-result]
asprintf(&arg, "%.*s", (int)(token_end - colon - 1), colon + 1);
^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
log.c: In function ‘fmtkv’:
log.c:646:5: warning: ignoring return value of ‘vasprintf’, declared with attribute warn_unused_result [-Wunused-result]
vasprintf(&buf1, fmt, ap);
^~~~~~~~~~~~~~~~~~~~~~~~~
mech/context.c: In function ‘gss_mg_set_error_string’:
mech/context.c:212:5: warning: ignoring return value of ‘vasprintf’, declared with attribute warn_unused_result [-Wunused-result]
(void) vasprintf(&str, fmt, ap);
^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
mech/context.c: In function ‘_gss_mg_log_name’:
mech/context.c:319:6: warning: ignoring return value of ‘vasprintf’, declared with attribute warn_unused_result [-Wunused-result]
(void) vasprintf(&str, fmt, ap);
^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
mech/context.c: In function ‘_gss_mg_log_cred’:
mech/context.c:346:5: warning: ignoring return value of ‘vasprintf’, declared with attribute warn_unused_result [-Wunused-result]
(void) vasprintf(&str, fmt, ap);
^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
kerberos5.c: In function ‘_kdc_set_e_text’:
kerberos5.c:338:5: warning: ignoring return value of ‘vasprintf’, declared with attribute warn_unused_result [-Wunused-result]
vasprintf(&e_text, fmt, ap);
^~~~~~~~~~~~~~~~~~~~~~~~~~~
Signed-off-by: Andrew Bartlett <abartlet@samba.org>
When a function is assigned to a function pointer that is declared
with a particular calling convention, then the assigned function
must be declared with that calling convention as well. Otherwise,
kaboom!!!
The following functions are fixed by this change:
kuser/kx509.c
validate1()
add1_2chain()
lib/base/log.c
log_syslog()
close_syslog()
log_file()
close_file()
lib/gssapi/mech/context.c
gss_set_log_function()
lib/krb5/kx509.c
certs_export_func()
Change-Id: Ib68abf739e3385e98136fa4e4f5a0240e9fce033
Add support for SAnon, a simple key agreement protocol that provides no
authentication of initiator or acceptor using x25519 ECDH key exchange.
See doc/standardization/draft-howard-gss-sanon-xx.txt for a protocol
description.
gss_release_cred_by_mech() was previously used by SPNEGO's implementation of
gss_set_neg_mechs(). This is now implemented in the mechanism glue. As we never
shipped gss_release_cred_by_mech(), it is safe to remove it and its exported
symbol.
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.
gss_add_oid_set_member() should according to RFC2744 add a copy of the OID to
the set; the current implementation just stored a pointer (which may not be
stable). As we have _gss_intern_oid(), call that before adding.
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.
gss_decapsulate_token() should return GSS_S_BAD_MECH if the mechanism did not
match the expected one, and GSS_S_DEFECTIVE_TOKEN if the token could not be
parsed for some other reason, rather than GSS_S_FAILURE in both cases
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.
The NegoEx gss_{exchange,query}_meta_data functions set allocated_ctx but never
did anything with it. Use it to determine whether we should free the context
handle on error.
_gss_secure_release_buffer_set() patch changed minor_status to 0, not
*minor_status as correct. No behavioural change as
_gss_secure_release_buffer_set() would have set it anyway, but obviously this
was unintentional.
Anonymous names should always compare FALSE in GSS_Compare_name(). If the names
are being compared at the mechglue layer then we should check for
GSS_C_NT_ANONYMOUS.
The prototype for gss_set_sec_context_option() allows it to return a new
context, however this was not implemented. This functionality is required by
GSS_KRB5_IMPORT_RFC4121_CONTEXT_X.
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
__gss_c_attr_stream_sizes_oid_desc was tagged with GSSAPI_LIB_FUNCTION instead
of GSSAPI_LIB_VARIABLE; whilst the macro expansion is identical, fix for
cleanliness
- 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?
This is the second of two commits in a series that must be picked together.
This series of two commits moves parts of lib/krb5/ infrastructure
functionality to lib/base/, leaving behind wrappers.
Some parts of libkrb5 are entirely generic or easily made so, and could
be useful in various parts of Heimdal that are not specific to the krb5
API, such as:
- lib/gssapi/ (especially since the integration of NegoEx)
- lib/hx509/
- bx509d (which should really move out of kdc/)
For the above we need to move these bits of lib/krb5/:
- lib/krb5/config_file.c (all of it, leaving forwardings behind)
- lib/krb5/config_reg.c (all of it)
- lib/krb5/plugin.c (all of it, leaving forwardings behind)
- lib/krb5/log.c (all of it, ditto)
- lib/krb5/heim_err.et (all of it)
And because of those two, these too must also move:
- lib/krb5/expand_path.c (all of it, leaving forwardings behind)
- lib/krb5/warn.c (just the warning functions, ditto)
The changes to the moved files are mostly quite straightforward and are
best reviewed with --word-diff=color.
We're also creating a heim_context and a heim API to go with it. But
it's as thin as possible, with as little state as necessary to enable
this move. Functions for dealing with error messages use callbacks.
Moving plugin.c does have one knock-on effect on all users of the old
krb5 plugin API (which remains), which is that a global search and
replace of struct krb5_plugin_data to struct heim_plugin_data was
needed, though the layout and size of that structure doesn't change, so
the ABI doesn't either.
As well, we now build lib/vers/ and lib/com_err/ before lib/base/ so as
to be able to move lib/krb5/heim_err.et to lib/base/ so that we can make
use of HEIM_ERR_* in lib/base/, specifically in the files that moved.
Once this is all done we'll be able to use config files and plugins in
lib/hx509/, we'll be able to move bx509d out of kdc/, and so on.
Most if not all of the new functions in lib/base/ are Heimdal-private,
thus calling conventions for them are not declared.
Status:
- builds and passes CIs (Travis, Appveyor)
- ran make check-valgrind and no new leaks or other memory errors
- ready for review
HOW TO REVIEW:
$ # Review file moves:
$ git log --stat -n1 HEAD^
$
$ # Review changes to moved files using --word-diff=color
$ git log -p -b -w --word-diff=color HEAD^..HEAD \
lib/base/config_file.c \
lib/base/config_reg.c \
lib/base/expand_path.c \
lib/base/warn.c \
lib/krb5/config_file.c \
lib/krb5/config_reg.c \
lib/krb5/expand_path.c \
lib/krb5/warn.c
$
$ # Review the whole thing, possibly adding -b and/or -w, and
$ # maybe --word-diff=color:
$ git log -p origin/master..HEAD
$ git log -p -b -w origin/master..HEAD
$ git log -p -b -w --word-diff=color origin/master..HEAD
TBD (future commits):
- make lib/gssapi use the new heimbase functions
- move kx509/bx509d common code to lib/hx509/ or other approp. location
- move bx509d out of kdc/
Initialize mechanism output parameters before calling mechanism
GSS_Accept_sec_context(), to behave robustly with poorly implemented mechanisms
that may return before initializing them.
NTLM erroneously requires a mechListMIC at the SPNEGO layer if an internal MIC
in the NTLM protocol was used. Add a private interface between SPNEGO and the
Samba NTLM mechanism to allow the mechanism to signal that a mechListMIC is
required even if it otherwise would not be.
This interface is the same as that supported by MIT.
Note that only the Samba NTLM mechanism currently implements this feature, it
is not implemented by the Heimdal NTLM mechanism (which does not support NTLM
authenticate message MICs).
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).
