Date: Sat, 13 Oct 2018 00:44:32 +0000 From: Rick Macklem <rmacklem@uoguelph.ca> To: Benjamin Kaduk <kaduk@mit.edu> Cc: Peter Eriksson <peter@ifm.liu.se>, Felix Winterhalter <felix@audiofair.de>, "freebsd-fs@freebsd.org" <freebsd-fs@freebsd.org> Subject: Re: NFSv4 Kerberos mount from Linux Message-ID: <YTOPR0101MB1820C98006C57A353F5FA573DDE30@YTOPR0101MB1820.CANPRD01.PROD.OUTLOOK.COM> In-Reply-To: <20181012033145.GC3293@kduck.kaduk.org> References: <30f6446c-6fed-4b1e-9cae-9c417974ec46@audiofair.de> <YTOPR0101MB1820A5756D172342AF441C25DDEA0@YTOPR0101MB1820.CANPRD01.PROD.OUTLOOK.COM> <c1ffda48-3809-bb4c-6d97-451765b0e25e@audiofair.de> <YTOPR0101MB18207F35A3973F26C6A58F6ADDE00@YTOPR0101MB1820.CANPRD01.PROD.OUTLOOK.COM> <33A0F0BC-4AD8-4DE3-B484-42B7FB208B6A@ifm.liu.se> <YTOPR0101MB1820439E0BFBF57DB2572E92DDE20@YTOPR0101MB1820.CANPRD01.PROD.OUTLOOK.COM>, <20181012033145.GC3293@kduck.kaduk.org>
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Benjamin Kaduk wrote: >I wrote: >> >> The one area you don't discuss (and maybe isn't really a problem?) is wh= at >> ticket encryption type(s) you use. >> Kerberized NFS still uses DES (someday this may change, but I think that= requires >> implementation of RPCSEC_GSS V3), so it needs an 8byte session key. > >This isn't true anymore; you can use stronger session keys just fine. >(See also RFC 6649 -- don't use single-DES!) I haven't read RFC6649, but from looking at the kgssapi code in FreeBSD's head/current, it appears that newer encryption types are used for wrap/unwr= ap (krb5p). >From what I can see, the following appear to be supported: DES, DES3, AES128, AES256, Arcfour, Arcfour_56 (I'll have to look at RFC6649 someday, because I've never seen an RFC speci= fying anything but DES for RPCSEC_GSS.) I won't even try to guess whether all of the above work for all implementat= ions, but it appears that it uses whatever the session key is (krb5_key_state?). Peter, do you happen to know what encryption type(s) you have been using? >> (I have never seen a documented way to convert a session key of greater = than >> 8bytes into an 8byte session key for RPCSEC_GSS to use. As such, I have= no idea >> what happens if you choose a ticket encryption type that results in a g= reater >> than 8byte key.) Ignore this. I just wasn't correct. rick [good stuff snipped]
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