Hello! On 31.07.2025 18:36, Cy Schubert wrote:
In message <20250731152803.19f9...@slippy.cwsent.com>, Cy Schubert writes:In message <CAM5tNy4XupPGXHMS0p0TK0Wf_zAg5bsOzx4C1K1e-_2b=3eyUw@mail.gmail.c om> , Rick Macklem writes:On Thu, Jul 31, 2025 at 6:51=E2=80=AFAM Rick Macklem <rick.mack...@gmail.co=m> wrote:On Thu, Jul 31, 2025 at 6:07=E2=80=AFAM Rick Macklem <rick.macklem@gmail.=com> wrote:On Wed, Jul 30, 2025 at 9:24=E2=80=AFPM Benjamin Kaduk <bjkfbsd@gmail.c=om> wrote:On Wed, Jul 30, 2025 at 10:36=E2=80=AFAM Rick Macklem <rick.macklem@g=mail.com> wrote:On Mon, Jul 28, 2025 at 3:32=E2=80=AFPM Benjamin Kaduk <bjkfbsd@gmai=l.com> wrote:On Mon, Jul 28, 2025 at 3:04=E2=80=AFPM Benjamin Kaduk <bjkfbsd@gm=ail.com> wrote:Note that MIT krb5 provides the gss_krb5_export_lucid_sec_context=() API that does a lot of the work of getting useful bits out of an establi=shed GSS security context.And a bit more context on what is going on here and why kgssapi ha=s to care:The GSS-API (RFC 2743) is all about a way to "establish a security=context" (i.e., do crypto negotiation, authentication, sometimes authoriza=tion, etc.) between two entities, the initiator and the acceprot, and then=exchanging protected messages between the two (which can be either encrypte=d or just integrity protection tags for otherweise cleartext data); later e=xtensions included the ability to produce identical PRF output on both part=ies, etc.. The details are "mechanism-specific", and for this purpose we'r=e exclusively talking about the krb5 mechanism. The steps to establish the=security context are complicated and sometimes fiddly, and in the general=case can require a large number of round-trips between the initiator and ac=ceptor before the security context is established. The individual message-=protection parts are comparatively simple and amendable to implementation i=n the kernel for processing efficiency.RFC 2743 also defines functions for GSS_Export_sec_context() and G=SS_Import_sec_context(), that are designed essentially to pass information=about an established security context from one process to another on the sa=me machine (which are presumably using the same implementation and version=of the implementation), so the contents of the exported blob are opaque and=implementation-specific. We are abusing that mechanism to export informat=ion about the security context that gssd has established and feed that info=rmation into the kernel implementation of the per-message processing routin=es. At present, this necessarily entails knowing the details of the implem=entation-specific opaque blob that is the "export sec context token", which=is what the sys/kgssapi/krb5/krb5_mech.c code is doing. But if we can get=the information we want without breaking the abstraction barrier, such as=via the gss_krb5_export_lucid_sec_context() API, we are in a more robust po=sture overall and somewhat future-proofed against future evolution by MIT k=rb5.(I note that recent Heimdal versions seem to also expose a gss_krb=5_export_lucid_sec_context() API, so part of the problem is just that the H=eimdal in base is so old.)Well, here's some "not so good" news... I've been trying to use gss_inquire_sec_context_by_oid(..) with the=oidfor the GSS_KRB5_EXPORT_LUCID_SEC_CONTEXT_OID with version 1. It kept failing. The problem seems to be that "gctx->proto =3D=3D 4" in make_external=_lucid_ctx_v1()function. This function only knows about the 0 and 1 setting for gct=x->proto.Any ideas, rickI'm not seeing anything to suggest that a "gctx->proto" value of 4 is=ever expected; it looks like it's supposed to just be 0 (for the legacy RF=C 1964 format) or 1 (for the "CFX" format of RFC 4121, with wider sequence=numbers for message-protection formats, etc.). So maybe it's worth posting=your current WIP somewhere to take a closer look at what's going on.Yea, the debugging I did was flawed (I probably got the wrong offset in the structure). It is weird, though. If I do gss_inquire_sec_context_by_oid(&minor, ctx=,OID_FOR_GSS_INQUIRE_SSPI_SESSION_KEY, &key), it works and gives me the key and encryption type. If I do the same, but with the 12 byte OID for LUCID v1 (the 11 bytes f=rom thestring + a 1 byte), it returns major =3D=3D GSS_S_COMPLETE, but no data=anda weird 39756046(decimal) or 0x25ea10e(hex) minor. (Oh, and I tried gss_krb5_export_lucid_sec_context() and got the same weird error.)--> Now (after doing a "make buildworld"), gss_krb5_export_lucid_sec_cont=ext()returns GSS_S_BAD_MECH. Looking at the src, that error has to be fro=mgss_inquire_sec_context_by_oid(). So, same function fails, but a dif=ferenterror return? It looks like "gssint_get_mechanism (ctx->mech_type)" is failing. I'm currently just passing GSS_C_NULL_OID into gss_init_sec_context(), but I've also tried the Kerberos 9 byte OID (both work, in the sense that gss_init_sec_context() seems to work, except that the actual_mech_type returned by it has a bogus pointer in the reply). --> It looks like the "mech_type" field of "ctx" is busted, for some reas=on?I'm going to try building krb5 from ports and linking to that, to see if=itdoes the same thing.Finally some good news... All I did was "pkg install krb5" and then linked the gssd to the libraries=in /usr/local/lib and it worked!!gssapi/gssapi.h from krb5/lib/gssapi/generic is overwritten by our lib/libgssapi. As we have two the MIT gssapi.h is put in /usr/include/gssapi_krb5/gssapi.h. This patch should fix the problem. I haven't tested this yet. diff --git a/usr.sbin/gssd/Makefile b/usr.sbin/gssd/Makefile index 569e2c7e18f5..4c9d342c48c3 100644 --- a/usr.sbin/gssd/Makefile +++ b/usr.sbin/gssd/Makefile @@ -14,7 +14,7 @@ LIBADD= gssapi .if ${MK_MITKRB5} != "no" # MIT KRB5 LIBADD+= krb5 k5crypto krb5profile krb5support -CFLAGS+= -DMK_MITKRB5=yes +CFLAGS+= -DMK_MITKRB5=yes -Iinclude/gssapi_krb5 .else # Heimdal LIBADD+= krb5 rokenNow I can test/debug the changes. Btw, the stuff in /usr/local/include/gssapi are correct and not messed up like the stuff in /usr/include/gssapi. (The ones in /usr/local/include defi=ne GSS_DLLIMP for example.) I'm going to leave figuring out why the libraries in /usr/lib are messed up to someone else. rickI had explained this to Lexi private moments ago. It's not that. gssapi.h is installed by lib/libgssapi, the gssapi forwarder. Heimdal had no gssapi.h whereas MIT KRB5 does. I put the MIT gssapi.h in /usr/include/gssapi_krb5 for apps that might need it.
And this leads to the mess due to rest of includes in /usr/include/gssapi comes from MIT and relying on gsspai.h from MIT too but it hidded by separated prefix and not hooked up by default.Great example of messing comes from evolution-data-server (or from any other consumer of #include <gssapi/gssapi_ext.h> or #include <gssapi/gssapi_generic.h> due to both want #include <gssapi/gssapi.h>):
In file included from
/wrkdirs/usr/ports/databases/evolution-data-server/work/evolution-data-server-3.56.2/src/camel/camel-sasl-gssapi.c:59:
/usr/include/gssapi/gssapi_generic.h:50:1: error: unknown type name 'GSS_DLLIMP'
50 | GSS_DLLIMP extern gss_OID gss_nt_user_name;
| ^
/usr/include/gssapi/gssapi_generic.h:50:26: error: expected ';' after top level
declarator
50 | GSS_DLLIMP extern gss_OID gss_nt_user_name;
| ^
/usr/include/gssapi/gssapi_generic.h:51:1: error: unknown type name 'GSS_DLLIMP'
51 | GSS_DLLIMP extern gss_OID gss_nt_machine_uid_name;
| ^
/usr/include/gssapi/gssapi_generic.h:51:26: error: expected ';' after top level
declarator
51 | GSS_DLLIMP extern gss_OID gss_nt_machine_uid_name;
| ^
/usr/include/gssapi/gssapi_generic.h:52:1: error: unknown type name 'GSS_DLLIMP'
52 | GSS_DLLIMP extern gss_OID gss_nt_string_uid_name;
| ^
/usr/include/gssapi/gssapi_generic.h:52:26: error: expected ';' after top level
declarator
52 | GSS_DLLIMP extern gss_OID gss_nt_string_uid_name;
| ^
/usr/include/gssapi/gssapi_generic.h:54:1: error: unknown type name 'GSS_DLLIMP'
54 | GSS_DLLIMP extern gss_OID gss_nt_service_name;
| ^
/usr/include/gssapi/gssapi_generic.h:54:26: error: expected ';' after top level
declarator
54 | GSS_DLLIMP extern gss_OID gss_nt_service_name;
| ^
8 errors generated.
Best way is install MIT's one gssapi.h alongside with other mit header under
/include/gssapi/ and move libgssapi's one under own prefix as you previously
did for mit one.
This was not a problem because Heimdal never had a gssapi.h while with MIT there is a conflict. Removing lib/libgssapi or its gssapi.h is not an option because it's a gssapi forwarder. This was the compromise I settled on.
-- Sincerely, Dima (flu...@freebsd.org, https://t.me/FluffyBSD, @fluffy:matrix-dev.freebsd.org) (desktop, kde, x11, office, ports-secteam)@FreeBSD team
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