Re: [PATCH 2.6.27-rc5] Allow set RLIMIT_NOFILE to RLIM_INFINITY

[Andrew Morton <akpm@linux-foundation.org>]

On Tue, 9 Sep 2008 09:14:07 +0200
Adam Tkac <vonsch@gmail.com> wrote:

> when process wants set limit of open files to RLIM_INFINITY it gets
> EPERM even if it has CAP_SYS_RESOURCE capability. Attached patch
> should fix the problem. Please add me to CC of your responses because
> I'm not member of list.
> 
> Regards, Adam
> 
> -- 
> Adam Tkac
> 
> 
> [linux26-openfiles.patch  text/plain (634B)]
> --- a/kernel/sys.c
> +++ b/kernel/sys.c
> @@ -1458,8 +1458,14 @@ asmlinkage long sys_setrlimit(unsigned i
>  	if ((new_rlim.rlim_max > old_rlim->rlim_max) &&
>  	    !capable(CAP_SYS_RESOURCE))
>  		return -EPERM;
> -	if (resource == RLIMIT_NOFILE && new_rlim.rlim_max > sysctl_nr_open)
> -		return -EPERM;
> +	if (resource == RLIMIT_NOFILE) {
> +		if (new_rlim.rlim_max == RLIM_INFINITY)
> +			new_rlim.rlim_max = sysctl_nr_open;
> +		if (new_rlim.rlim_cur == RLIM_INFINITY)
> +			new_rlim.rlim_cur = sysctl_nr_open;
> +		if (new_rlim.rlim_max > sysctl_nr_open)
> +			return -EPERM;
> +	}

The kernel has had this behaviour for a long time.  2.6.13 had:

	if ((new_rlim.rlim_max > old_rlim->rlim_max) &&
	    !capable(CAP_SYS_RESOURCE))
		return -EPERM;
	if (resource == RLIMIT_NOFILE && new_rlim.rlim_max > NR_OPEN)
			return -EPERM;

I don't immediately see a problem with your change, but what makes you
believe that it is needed?  Is there some standard which we're
violating?  Is there some operational situation in which the current
behaviour is causing a problem?

Thanks.