HXBC.us - 竹難月金

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> [`runas`](http://hxbc.us/software/runas/runas.tar.gz) is a tool that executes commands as other users. It sets up xauth and some environmental variables so that X applications (currently I am running gaim and firefox through runas) work.
> 
> ## Why?
> 
> The rationale is similar to Vista's reduced privilege mode for IE7. If a remote vulnerability is exploited in an application the damage is limited (unless other local exploits are used to gain root privileges).
> 
> Although their goals are similar, `runas` was not inspired by the so-called "Low-Rights IE". I first had the idea and initial implementation (which never worked) some time in 2005, before such a mode was announced for IE7. Obviously numerous daemons before that also implemented their own privilege dropping. Unlike those mechanisms, `runas` enables privilege dropping for arbitrary programs that did not have the feature built in.
> 
> ## Usage
> 
> Extract the tarball, make && make install, then copy runas.conf to /etc and modify for your environment. `runas` does not create the users and groups listed in runas.conf, so you will need to create them yourself:
> 
>     sudo adduser --disabled-login webbrowser
> 
> If you want to keep your existing profiles for firefox where they are, some extra steps are needed:
> 
>     sudo chgrp -R webbrowser .mozilla
>     # make files g+rwx where appropriate 
>     for f in `find .mozilla`; do if [ -x $f ]; then sudo chmod g+x $f; fi; done
>     for f in `find .mozilla`; do if [ -w $f ]; then sudo chmod g+w $f; fi; done
>     for f in `find .mozilla`; do if [ -r $f ]; then sudo chmod g+r $f; fi; done
> 
> You also need to change your default browser to `runas /usr/bin/firefox %s` if you want links from other applications to work correctly. If you use GNOME, this can be done in gnome-default-applications-properties.
> 
> In addition to that, I also created a ~/Desktop/Downloads directory under my normal user and marked it group webbrowser and group writable. I changed my firefox download directory to that so I can grab the files I downloaded easily.
> 
> I've only tested `runas` under Linux (Ubuntu Edgy), although it will probably work in other unix environments assuming that glib and the development headers are installed.
> 
> ## How secure is this?
> 
> Since `runas` is a setuid binary, Very Bad Things can happen if something goes wrong. Just keep in mind that `runas` comes with no warranty :-)
> 
> `runas` also does not prevent exploits like the recent [Nvidia driver exploit](http://kerneltrap.org/node/7228) that directly target the X server/drivers.
> 
> `runas.conf` should only list commands using absolute path.
> 
> `runas` is also not suited for environments where there are more than one real user, because the configuration is global. This may change in a later version.