Re: syscall: sys_promote

[Erik Mouw]

On Fri, Aug 26, 2005 at 05:25:37PM +0800, Coywolf Qi Hunt wrote:
> I just wrote a tool with kernel patch, which is to set the uid's of a running
> process without FORK.
> 
> The tool is at http://users.freeforge.net/~coywolf/pub/promote/
> Usage: promote <pid> [uid]
> 
> I once need such a tool to work together with my admin in order to tune my web
> configuration.  I think it's quite convenient sometimes. 
> 
> The situations I can image are:
> 
> 1) root processes can be set to normal priorities, to serve web
> service for eg.

Most (if not all) web servers can be told to drop all privileges and
run as a normal user. If not, you can use selinux to create a policy
for such processes (IIRC that's what Fedora does).

> 2) admins promote trusted users, so they can do some system work without knowing
>    the password

Use sudo for that, it allows even much finer grained control.

> 3) admins can `promote' a suspect process instead of killing it.

Why would that change anything? You only change a process's UID,
nothing else. You don't change things like resource limits, so a
process started as root with unlimited limits is still allowed to use
those limits. AFAIK setrlimit() can't be used to change resource limits
of other processes.


Erik

-- 
+-- Erik Mouw -- www.harddisk-recovery.com -- +31 70 370 12 90 --
| Lab address: Delftechpark 26, 2628 XH, Delft, The Netherlands
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