[Bug 1779962] Re: rpc.gssd truncates 32-bit UIDs/GIDs to 16 bits, leading to "Key has expired" errors when using kerberos

[Steve Dickson]

The upstream patch

commit 2a6b8307fa4243a7921270aedf8ce6506e31569a (HEAD -> master, origin/master, origin/HEAD)
Author: Steve Dickson <steved at redhat.com>
Date:   Tue Jul 17 15:09:37 2018 -0400

    rpc.gssd: truncates 32-bit UIDs/GIDs to 16 bits architectures.
    
    utils/gssd_proc.c uses SYS_setresuid and SYS_setresgid in
    change_identity when it should use SYS_setresuid32 and
    SYS_setresgid32 instead. This causes it to truncate
    UIDs/GIDs > 65536.
    
    Fixes: https://bugs.launchpad.net/ubuntu/+source/nfs-utils/+bug/1779962
    Fixes: https://bugzilla.redhat.com/show_bug.cgi?id=1595927
    
    Tested-by: James Ettle <theholyettlz at googlemail.com>
    Tested-by: Sree <Sree at gmail.com>
    Signed-off-by: Steve Dickson <steved at redhat.com>


** Bug watch added: Red Hat Bugzilla #1595927
   https://bugzilla.redhat.com/show_bug.cgi?id=1595927

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https://bugs.launchpad.net/bugs/1779962

Title:
  rpc.gssd truncates 32-bit UIDs/GIDs to 16 bits, leading to "Key has
  expired" errors when using kerberos

Status in nfs-utils package in Ubuntu:
  Confirmed

Bug description:
  utils/gssd_proc.c uses SYS_setresuid and SYS_setresgid in
  change_identity when it should use SYS_setresuid32 and SYS_setresgid32
  instead. This causes it to truncate UIDs/GIDs > 65536.

  Symptoms: rpc.gssd is unable to read kerberos credentials files after
  changing identity, failing with a cryptic error message:

  CC 'FILE:/tmp/krb5cc_100001_J5kIrv' is expired or corrupt

  (note the UID 100001 here, rpc.gssd was actually using UID 34465 to
  access this file, and failing in krb5_util.c when calling
  krb5_cc_get_principal)

  The attached patch fixes the bug.

  I'm using Ubuntu 18.04 LTS on an Odroid XU4 (armhf). This bug does not
  exist in Ubuntu 16.04 LTS.

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