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Groups > linux.debian.bugs.dist > #1270579

Bug#1120598: ls input/output error ("NFS: readdir(/) returns -5") on krb5 NFSv4 client using SHA2

From Scott Mayhew <smayhew@redhat.com>
Newsgroups linux.debian.bugs.dist, linux.kernel, linux.debian.kernel
Subject Bug#1120598: ls input/output error ("NFS: readdir(/) returns -5") on krb5 NFSv4 client using SHA2
Date 2025-11-18 00:10 +0100
Message-ID <LSgw9-dK5j-9@gated-at.bofh.it> (permalink)
References (7 earlier) <LRPFD-ds93-3@gated-at.bofh.it> <LRPFD-ds93-1@gated-at.bofh.it> <LRZYl-dz0H-1@gated-at.bofh.it> <LQqSZ-cvae-3@gated-at.bofh.it> <LRZYl-dz0H-1@gated-at.bofh.it>
Organization linux.* mail to news gateway

Cross-posted to 3 groups.

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On Mon, 17 Nov 2025, Tyler W. Ross wrote:

> Weird behavior I just discovered:
> 
> Explicitly setting allowed-enctypes in the gssd section of /etc/nfs.conf
> to exclude aes256-cts-hmac-sha1-96 makes both SHA2 ciphers work as
> expected (assuming each is allowed).
> 
> If allowed-enctypes is unset (letting gssd interrogate the kernel for
> supported enctypes) or includes aes256-cts-hmac-sha1-96, then the XDR
> overflow occurs.
> 
> Non-working configurations (first is the commented-out default in nfs.conf):
> allowed-enctypes=aes256-cts-hmac-sha384-192,aes128-cts-hmac-sha256-128,camellia256-cts-cmac,camellia128-cts-cmac,aes256-cts-hmac-sha1-96,aes128-cts-hmac-sha1-96
> allowed-enctypes=aes256-cts-hmac-sha384-192,aes256-cts-hmac-sha1-96
> allowed-enctypes=aes128-cts-hmac-sha256-128,aes256-cts-hmac-sha1-96
> allowed-enctypes=aes256-cts-hmac-sha384-192,aes128-cts-hmac-sha256-128,aes256-cts-hmac-sha1-96
> 
> Working configurations (first is default sans aes256-cts-hmac-sha1-96):
> allowed-enctypes=aes256-cts-hmac-sha384-192,aes128-cts-hmac-sha256-128,camellia256-cts-cmac,camellia128-cts-cmac,aes128-cts-hmac-sha1-96
> allowed-enctypes=aes256-cts-hmac-sha384-192,aes128-cts-hmac-sha256-128
> allowed-enctypes=aes256-cts-hmac-sha384-192,aes128-cts-hmac-sha1-96
> allowed-enctypes=aes128-cts-hmac-sha256-128,aes128-cts-hmac-sha1-96
> 

That doesn't really make sense.  You should only need to use the
allowed-enctypes setting if you're talking to an NFS server that doesn't
have support for the new encryption types.

It basically works like the "permitted_enctypes" option in krb5.conf,
except it only affects NFS rather than affecting your krb5 configuration
as a whole.

Can you go back and re-do the tracepoint capture, except this time
umount your NFS filessytems before starting the capture (i.e. perform
the mount command while trace-cmd is running).  I'm curious what values
the rpcgss_update_slack tracepoint shows.

> 
> Is this gssd mishandling some setup/initialization?
> Or is there a miscalculation happening somewhere further up?
> 
> 
> TWR
>

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Bug#1120598: ls input/output error ("NFS: readdir(/) returns -5") on krb5 NFSv4 client using SHA2 "Tyler W. Ross" <TWR@tylerwross.com> - 2025-11-13 18:20 +0100
  Bug#1120598: ls input/output error ("NFS: readdir(/) returns -5") on krb5 NFSv4 client using SHA2 "Tyler W. Ross" <TWR@tylerwross.com> - 2025-11-13 19:10 +0100
    Bug#1120598: ls input/output error ("NFS: readdir(/) returns -5") on krb5 NFSv4 client using SHA2 "Tyler W. Ross" <TWR@tylerwross.com> - 2025-11-13 20:00 +0100
  Bug#1120598: ls input/output error ("NFS: readdir(/) returns -5") on krb5 NFSv4 client using SHA2 "Tyler W. Ross" <TWR@tylerwross.com> - 2025-11-14 05:40 +0100
    Bug#1120598: ls input/output error ("NFS: readdir(/) returns -5") on krb5 NFSv4 client using SHA2 "Tyler W. Ross" <TWR@tylerwross.com> - 2025-11-14 06:20 +0100
      Bug#1120598: ls input/output error ("NFS: readdir(/) returns -5") on krb5 NFSv4 client using SHA2 "Tyler W. Ross" <TWR@tylerwross.com> - 2025-11-16 01:50 +0100
        Bug#1120598: ls input/output error ("NFS: readdir(/) returns -5") on krb5 NFSv4 client using SHA2 Trond Myklebust <trondmy@kernel.org> - 2025-11-16 19:30 +0100
          Bug#1120598: ls input/output error ("NFS: readdir(/) returns -5") on krb5 NFSv4 client using SHA2 "Tyler W. Ross" <TWR@tylerwross.com> - 2025-11-17 06:30 +0100
            Bug#1120598: ls input/output error ("NFS: readdir(/) returns -5") on krb5 NFSv4 client using SHA2 "Tyler W. Ross" <TWR@tylerwross.com> - 2025-11-17 19:50 +0100
            Bug#1120598: ls input/output error ("NFS: readdir(/) returns -5") on krb5 NFSv4 client using SHA2 Scott Mayhew <smayhew@redhat.com> - 2025-11-18 00:10 +0100
          Bug#1120598: ls input/output error ("NFS: readdir(/) returns -5") on krb5 NFSv4 client using SHA2 Scott Mayhew <smayhew@redhat.com> - 2025-11-18 00:10 +0100
            Bug#1120598: ls input/output error ("NFS: readdir(/) returns -5") on krb5 NFSv4 client using SHA2 "Tyler W. Ross" <TWR@tylerwross.com> - 2025-11-18 05:20 +0100
              Bug#1120598: ls input/output error ("NFS: readdir(/) returns -5") on krb5 NFSv4 client using SHA2 Scott Mayhew <smayhew@redhat.com> - 2025-11-18 19:00 +0100
                Bug#1120598: ls input/output error ("NFS: readdir(/) returns -5") on krb5 NFSv4 client using SHA2 "Tyler W. Ross" <TWR@tylerwross.com> - 2025-11-19 00:50 +0100
                Bug#1120598: ls input/output error ("NFS: readdir(/) returns -5") on krb5 NFSv4 client using SHA2 Scott Mayhew <smayhew@redhat.com> - 2025-11-19 14:40 +0100

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