[Bug 1812280] Re: Static ID mapping not functional in NFS

[Andreas Hasenack]

I confirmed the brokeness of this feature in the current packaging, and
also that it is fixed in the new one I'm working on, from the ppa linked
in the bug above.

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Title:
  Static ID mapping not functional in NFS

Status in libnfsidmap package in Ubuntu:
  Triaged

Bug description:
  Static NFS UID/GID translation doesn't work, even when using with
  sec=krb5.

  The share is exported with:

  /nfs
  192.168.0.0/24(rw,sync,crossmnt,no_subtree_check,root_squash,fsid=0,sec=krb5)

  Mapping configuration in /etc/idmapd.conf:

  ...
  [Translation]
  Method = static

  [Static]
  sam at home.lan = sam 
  bob at home.lan = bob 
  ...

  Logs from rpc.idmapd:

  ...
  rpc.idmapd[3591]: libnfsidmap: processing 'Method' list
  libnfsidmap: loaded plugin /lib/x86_64-linux-gnu/libnfsidmap/static.so for method static
  rpc.idmapd[3592]: Expiration time is 600 seconds.
  rpc.idmapd[3592]: Opened /proc/net/rpc/nfs4.nametoid/channel
  rpc.idmapd[3592]: Opened /proc/net/rpc/nfs4.idtoname/channel
  ...
  rpc.idmapd[3592]: nfsdcb: authbuf=gss/krb5 authtype=user
  rpc.idmapd[3592]: nfs4_uid_to_name: final return value is 0
  rpc.idmapd[3592]: Server : (user) id "1000" -> name ""
  rpc.idmapd[3592]: nfsdcb: authbuf=gss/krb5 authtype=group
  rpc.idmapd[3592]: nfs4_gid_to_name: final return value is 0
  rpc.idmapd[3592]: Server : (group) id "1000" -> name ""
  rpc.idmapd[3592]: nfsdcb: authbuf=gss/krb5 authtype=group
  rpc.idmapd[3592]: nfs4_gid_to_name: final return value is 0
  rpc.idmapd[3592]: Server : (group) id "1003" -> name ""
  rpc.idmapd[3592]: nfsdcb: authbuf=gss/krb5 authtype=user
  rpc.idmapd[3592]: nfs4_uid_to_name: final return value is 0
  rpc.idmapd[3592]: Server : (user) id "0" -> name ""
  rpc.idmapd[3592]: nfsdcb: authbuf=gss/krb5 authtype=group
  rpc.idmapd[3592]: nfs4_gid_to_name: final return value is 0
  rpc.idmapd[3592]: Server : (group) id "0" -> name ""
  rpc.idmapd[3592]: nfsdcb: authbuf=gss/krb5 authtype=user
  rpc.idmapd[3592]: nfs4_uid_to_name: final return value is 0
  rpc.idmapd[3592]: Server : (user) id "1002" -> name ""
  rpc.idmapd[3592]: nfsdcb: authbuf=gss/krb5 authtype=group
  rpc.idmapd[3592]: nfs4_gid_to_name: final return value is 0
  rpc.idmapd[3592]: Server : (group) id "1002" -> name ""
  ...

  
  As you can see, even though static.so plugin was loaded, ID translation was not performed.

  Looking at this issue with GDB shows that static translation plugin is
  skipped in these two lines in libnfsidmap.c:

  ...
  if (plgns[i]->trans->funcname == NULL)
      continue;
  ...

  The reason that funcname is null is that pointers to name_to_uid,
  name_to_gid, uid_to_name, gid_to_name are explicitly initialized to
  NULL in the Ubuntu's version of libnfsidmap/static.c:

  ...
  struct trans_func static_trans = {
          .name                   = "static",
          .init                   = NULL,
          .name_to_uid            = NULL,
          .name_to_gid            = NULL,
          .uid_to_name            = NULL,
          .gid_to_name            = NULL,
          .princ_to_ids           = static_gss_princ_to_ids,
          .gss_princ_to_grouplist = static_gss_princ_to_grouplist,
  };
  ...

  Please note, that in original sources of NFS these callbacks are
  correctly initialized like so:

  ...
  struct trans_func static_trans = {
  	.name			= "static",
  	.init			= static_init,
  	.name_to_uid		= static_name_to_uid,
  	.name_to_gid		= static_name_to_gid,
  	.uid_to_name		= static_uid_to_name,
  	.gid_to_name		= static_gid_to_name,
  	.princ_to_ids		= static_gss_princ_to_ids,
  	.gss_princ_to_grouplist	= static_gss_princ_to_grouplist,
  };
  ...

  I am not sure why in Ubuntu's package the NFS static ID translation
  was disabled, but if it was done deliberately it should've been
  documented (maybe here https://help.ubuntu.com/community/NFSv4Howto
  ?).

  Side note: nsswitch translation works correctly.

  Ubuntu Server 18.04.1 LTS
  libnfsidmap2:amd64 0.25-5.1

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