[CentOS] Re: NFSroot is acting strange in CentOS5

[Scott Silva]

on 2/26/2008 5:31 PM vincenzo romero spake the following:
> Hello all,
> 
> I have observed a problem with a diskless PXE client I am attempting
> to configure. PXE/NFS/DHCP/TFTPd server is running CentOS5.1 and the
> Diskless workstation's root and kernel was extracted from a CentOS5.1
> (custom kernel due to setting to enable Root File System support).
> 
> Problem:  When the diskless client boots and logs in I notice that my
> root user is being squashed, even if I have exported the root with the
> "no_root_squash" option.  The exports file contains this line:
> /export/images                  *(rw,no_root_squash,no_subtree_check)
> 
> 1.  Creating a file as root gives it nobody permission:
> rw-r--r--  1 65534 65534    0 Feb 26 16:30 foo
> 2.  When I explicitly mount the same export from the booted
> workstation and create another file; this time, it is created as root:
> -rw-r--r--  1 root  root     0 Feb 26 16:31 bar
> 
> 3.  I checked the /proc/mounts and notice there are differences in the
> NFS options it has accepted during mount:
> rootfs / rootfs rw 0 0
> /dev/root / nfs
> rw,vers=2,rsize=4096,wsize=4096,hard,nolock,proto=udp,timeo=11,retrans=2,sec=null,addr=192.16.10.5
> 0 0
> 
> 192.16.10.5:/tftpboot /mnt/test nfs
> rw,vers=3,rsize=32768,wsize=32768,hard,proto=tcp,timeo=600,retrans=2,sec=sys,addr=192.168.16.5
> 0 0
> 
> 4.  I try to append NFS options to my APPEND line to force:  NFS
> version3, change r/wsize, use tcp protocol and change the sec from
> null to sys (null seems to be the parameter that affects the NFS
> ownership/permission).  My /tftpboot/pxelinux.cfg/default file
> contains the following:
> 
> nfsroot=192.168.16.5:/export/images/centos51_x86-64,nfsversvers=3,tcp,rsize=32768,wsize=32768,sec=sys
> ip=dhcp
> 
> 5.  All options are honored except for the "sec=sys" option.  Below is
> the output of the /proc/cmdline:
> 
> /proc/cmdline:
> root=/dev/nfs rw
> nfsroot=192.168.16.5:/export/images/centos51_x86-64,nfsvers=3,tcp,rsize=32768,wsize=32768,sec=sys
> ip=dhcp BOOT_IMAGE=vmlinuz-2.6.18-custom-2.6.18-53.el5
> 
> 6.  But the /proc/mounts shows that the "sec=" parameter is still set to NULL.
> /proc/mounts:
> rootfs / rootfs rw 0 0
> /dev/root / nfs
> rw,vers=3,rsize=3278,wsize=3478,hard,nolock,proto=tcp,timeo=11,retrans=2,sec=null,addr=192.168.16.5
> 0 0
> 
> ............
> 
> Kernel versions:
> 
> PXE server -->  uname -a
> Linux qatest1 2.6.18-53.1.13.el5xen #1 SMP Tue Feb 12 13:33:07 EST
> 2008 x86_64 x86_64 x86_64 GNU/Linux
> 
> Diskless Workstation's kernel and root are extracted from this:  Linux
> localhost.localdomain 2.6.18-custom-2.6.18-53.el5 #1 SMP Wed Feb 20
> 08:45:23 PST 2008 x86_64 x86_64 x86_64 GNU/Linux
> 
> Any help would be greatly appreciated.
> 
I haven't done this in a long time but do your workstation kernels have root 
nfs in them?
config_root_nfs
This could be obsolete these days.

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