Public bug reported:
Step to reproduse:
- Crete dircetory with other directories and files.
- Chown some files in this directory, set any non-root permissions.
- Export nfs share with 'ro' permissions.
- Mount nfs share.
- Mount ovrelayfs with nfs as lowerdir
- Try to read theese non-root files or directories:
Example for overlay mount:
# ls -l /var/lib/libvirt
total 16
drwx--x--x 2 root root 4096 Oct 10 07:33 boot
drwx--x--x 2 root root 4096 Oct 10 07:33 images
drwxr-x--- 3 libvirt-qemu kvm 4096 Jan 11 21:49 qemu
drwx------ 2 root root 4096 Oct 10 07:33 sanlock
# ls -l /var/lib/libvirt/qemu/
ls: cannot open directory '/var/lib/libvirt/qemu/': Operation not supported
And for nfs mount:
# ls -l /rofs/var/lib/libvirt
total 16
drwx--x--x 2 root root 4096 Oct 10 07:33 boot
drwx--x--x 2 root root 4096 Oct 10 07:33 images
drwxr-x--- 3 libvirt-qemu kvm 4096 Jan 11 21:49 qemu
drwx------ 2 root root 4096 Oct 10 07:33 sanlock
# ls -l /rofs/var/lib/libvirt/qemu/
total 4
drwxr-xr-x 3 root root 4096 Jan 11 21:49 channel
If I reset permission, it helps:
# chown libvirt-qemu:kvm /var/lib/libvirt/qemu
# ls -l /var/lib/libvirt/qemu/
total 4
drwxr-xr-x 3 root root 4096 Jan 11 21:49 channel
My mounts (from /proc/mounts)
192.168.101.61:/data/opt/ltsp/amd64 /rofs nfs
ro,relatime,vers=3,rsize=1048576,wsize=1048576,namlen=255,hard,nolock,proto=tcp,port=2049,timeo=7,retrans=10,sec=sys,local_lock=all,addr=192.168.101.61
0 0
overlay / overlay
rw,relatime,lowerdir=/rofs,upperdir=/cow/up,workdir=/cow/work 0 0
I tested it nfs3 and nfs4 mount, with this kenels:
# uname -a
Linux controller03 4.4.0-62-generic #83-Ubuntu SMP Wed Jan 18 14:10:15 UTC
2017 x86_64 x86_64 x86_64 GNU/Linux
# uname -a
Linux m1c18n1 4.8.0-36-generic #36~16.04.1-Ubuntu SMP Sun Feb 5 09:39:57
UTC 2017 x86_64 x86_64 x86_64 GNU/Linux
** Affects: linux (Ubuntu)
Importance: Undecided
Status: Incomplete
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https://bugs.launchpad.net/bugs/1665921
Title:
OverlayFS with readonly NFS lower layer. Operation not supported for
non-root files.
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