svn commit: r334543 - head/usr.bin/top

[Rodney W. Grimes]

> Author: eadler
> Date: Sat Jun  2 22:06:27 2018
> New Revision: 334543
> URL: https://svnweb.freebsd.org/changeset/base/334543
> 
> Log:
>   top(1): chdir to / as init; remove unneeded comment
>   
>   - chdir to / to allow unmounting of wd
>   - remove warning about running top(1) as setuid. If this is a concern we
>   should just drop privs instead.
> 
> Modified:
>   head/usr.bin/top/machine.c
>   head/usr.bin/top/top.c
> 
> Modified: head/usr.bin/top/machine.c
> ==============================================================================
> --- head/usr.bin/top/machine.c	Sat Jun  2 21:50:00 2018	(r334542)
> +++ head/usr.bin/top/machine.c	Sat Jun  2 22:06:27 2018	(r334543)
> @@ -1613,11 +1613,6 @@ compare_ivcsw(const void *arg1, const void *arg2)
>  /*
>   * proc_owner(pid) - returns the uid that owns process "pid", or -1 if
>   *		the process does not exist.
> - *		It is EXTREMELY IMPORTANT that this function work correctly.
> - *		If top runs setuid root (as in SVR4), then this function
> - *		is the only thing that stands in the way of a serious
> - *		security problem.  It validates requests for the "kill"
> - *		and "renice" commands.
>   */
>  
>  int
> 
> Modified: head/usr.bin/top/top.c
> ==============================================================================
> --- head/usr.bin/top/top.c	Sat Jun  2 21:50:00 2018	(r334542)
> +++ head/usr.bin/top/top.c	Sat Jun  2 22:06:27 2018	(r334543)
> @@ -260,6 +260,15 @@ main(int argc, char *argv[])
>  #define CMD_order	26
>  #define CMD_pid		27
>  
> +    /*
> +     * Since top(1) is often long running and
> +     * doesn't typically care about where its running from
> +     * chdir to the root to allow unmounting of its
> +     * originall wd. Failure is alright as this is
> +     * just a courtesy for users.
> +     */
> +    chdir("/");
> +

Bad side effect of doing that is it is not hard to get a "core"
from top when run as a user, as it is going to try to write
to /, and it probably does not have permission for that.

Better might be a cd to /tmp, or /var/tmp, which are usually
hard to unmount for these reasons anyway.

>      /* set the buffer for stdout */
>  #ifdef DEBUG
>      extern FILE *debug;
> 
> 

-- 
Rod Grimes                                                 rgrimes at freebsd.org