filesystem option "suid or nosuid"

[Marylou Kohlmeier]

Our /opt filesystem is presently mounted with neither "suid" nor "nosuid" option. What is the effect if I modified our /opt and apply "suid".

[Ganesan R]

Hi,

By default the filesystems will be mounted with suid option though it is not mentioned in fstab file. And /opt is preferred to be mounted with suid option.

Mounting the filesystem with "nosuid" keeps everyone to run SUID programs i.e. to start a program not under the UID of the starter but the owner of the file.

And moreover setting this option needs unmount of that filesystems.

Hope this helps.

[James R. Ferguson]

Hi:

Mounting a filesystem with the 'nosuid' option disables the 'setuid' action. If you mount a filesystem this way and attempt to execute a 'setuid' binary existing in that filesystem, you see:

Setuid execution not allowed

By example, if you mounted '/usr' as a 'nosuid' filesystem, then whenever a noraml users user attempted to change his/her password, they would be denied. This is because it is the 'setuid' bit and the 'root' ownership of the 'passwd' executable that confer an effective UID of 'root' to the normal user when (s)he runs the 'passwd' command.

Before doing something like this, make sure that you know what your filesystem contains:

# find /path -perm -4000

...will find all 'setuid' files.

Regards!

...JRF...

[Marylou Kohlmeier]

Thank you for all your replies. Presently, this is what I have for our /opt:

/dev/vg00/lvol6 /opt vxfs delaylog 0 2

I just want to clarity, since it's not specified, it the default "suid"?

[James R. Ferguson]

Hi (again):

> I just want to clarity, since it's not specified, it the default "suid"?

Yes.

Regards!

...JRF...

[Marylou Kohlmeier]

Thank you and have a nice day