"Permissions Denied" error as root: SOLVED

[Stuart Sears]

R. G. Newbury wrote:
> R. G. Newbury wrote:
> To recap, attempting to run a script, as root, with permissions 755
> produced a 'Permissions denied' error.
> 
> The problem was that the partition was mounted with 'users,defaults'
> options, and 'users' implies 'noexec' and overrides 'defaults' (which
> implies 'exec'),
> 
> Changing the line in fstab to 'defaults' and quick 'umount' and 'mount'
> fixed the problem.

another trick is this:

mount -o remount /mount/point

will change the mount options without actually unmounting the device in
question.

> Weird bit is that I was logged in as root..WHICH WAS MISLEADING.

I am curious as to how you thought you had been misled... or was this an
assumption that there are absolutely no restrictions on what the root
user can do?

> 'nonexec' is set, ALL users are denied execution privileges. (This is
> most useful for security purposes in denying the use of programs on for
> example a USB stick from compromising the system.

There are other uses for it too.
It is not all that uncommon to have /tmp and /home (and other
mountpoints that should not really have executable files on them) mount
noexec as well.

> So, besides checking the permissions on a file, and the parent
> directories, you have to check how the partition was mounted.
> This will catch you when you are playing with something on a 'spare'
> partition. Or when you change the fstab without realizing the implications!

True. 'users' and 'user' are not default options and tbh I don't see the
point of using them most of the time. IMO the only devices that users
should be mounting/unmounting are physically removable devices.

> Thanks to all for the pointers, which gave the solution.

glad we could help :)


Stuart
-- 
Stuart Sears RHCA etc.
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