gssd regression, "Program lacks support for encryption type"

Jochen <email address hidden> writes:

> After upgrading the krb5 libraries to 1.8 I could not mount my
> Kerberized NFS4 shares. The following error Message is in the syslog for
> every mount attempt:

> rpc.gssd[1298]: rpcsec_gss: gss_init_sec_context: (major) Unspecified
> GSS failure. Minor code may provide more information - (minor) Program
> lacks support for encryption type

> Switching back to 1.7 fixes this Problem.

Sounds like NFS v4 doesn't support stronger encryption types than DES.
You'll need to add:

    allow_weak_crypto = true

to the [libdefaults] section of your krb5.conf file.

--
Russ Allbery (<email address hidden>) <http://www.eyrie.org/~eagle/>

>>>>> "Russ" == Russ Allbery <email address hidden> writes:

    Russ> Jochen <email address hidden> writes:
    >> After upgrading the krb5 libraries to 1.8 I could not mount my
    >> Kerberized NFS4 shares. The following error Message is in the
    >> syslog for every mount attempt:

    >> rpc.gssd[1298]: rpcsec_gss: gss_init_sec_context: (major)
    >> Unspecified GSS failure. Minor code may provide more information
    >> - (minor) Program lacks support for encryption type

    >> Switching back to 1.7 fixes this Problem.

    Russ> Sounds like NFS v4 doesn't support stronger encryption types
    Russ> than DES. You'll need to add:

    Russ> allow_weak_crypto = true

    Russ> to the [libdefaults] section of your krb5.conf file.

Right. I really think this is a gssd bug: the NFS folks have have
multiple years to implement something stronger than DES. Unlike with
OpenAFS, the protocol has been quite clear; it's purely a matter of
writing code.

The work around Russ suggests is the right user-level fix. My comments
are more intended to address what the focus should be for the
distributions in terms of fixing this.

We're adding an API to krb5 to fix this for OpenAFS. Because of the way
the API is constructed, it's very difficult for GSSD to actually call
it.

"the NFS folks have have multiple years to implement something stronger than DES. Unlike with
OpenAFS, the protocol has been quite clear; it's purely a matter of writing code."

Yeah, the code is finally merged for 2.6.35, but that took longer than it should. (If you know anyone interested in funding NFS security work....)

"We're adding an API to krb5 to fix this for OpenAFS. Because of the way
the API is constructed, it's very difficult for GSSD to actually call
it."

Do you have a pointer to the details?

>>>>> "J" == J Bruce Fields <email address hidden> writes:

    J> "We're adding an API to krb5 to fix this for OpenAFS. Because of
    J> the way the API is constructed, it's very difficult for GSSD to
    J> actually call it."

    J> Do you have a pointer to the details?

/* Allows the appplication to override the profile's allow_weak_crypto setting.
 * Primarily for use by aklog. */
krb5_error_code KRB5_CALLCONV
krb5_allow_weak_crypto(krb5_context context, krb5_boolean enable);

The problem of course being the need for a krb5 context.