Re: [RFC PATCH 3/5] use next syscall data to predefine process ids

[Nadia Derbey <Nadia.Derbey-6ktuUTfB/bM@public.gmane.org>]

Eric W. Biederman wrote:
> Nadia.Derbey-6ktuUTfB/bM@public.gmane.org writes:
> 
> 
>>[PATCH 03/05]
>>
>>This patch uses the value written into the next_syscall_data proc file
>>as a target upid nr for the next process to be created.
>>The following syscalls have a new behavior if next_syscall_data is set:
>>. fork()
>>. vfork()
>>. clone()
>>
>>In the current version, if the process belongs to nested namespaces, only
>>the upper namespace level upid nr is allowed to be predefined, since there
>>is not yet a way to take a snapshot of upid nrs at all namespaces levels.
>>
>>But this can easily be extended in the future.
> 
> 
> This patch is unnecessary.  The and a mess.   The existing limits on the pid range should
> be enough.  We may need to export it via /proc/sys.
> 

Eric,

If I correctly understood what you're saying, it means set min = max = 
target_pid using /proc/sys, i.e. for the whole system: don't you think 
this might be dangerous: allocating pids will fail for any other running 
process  during the entire period of time where /proc/sys will be set 
like that.
I really think this is a feature that should be confined to a process.

Regards,
Nadia