Multi-process limitations when using the dumpcap tool

Multi-process limitations when using the dumpcap tool

[Isaac Boukris]

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Hello,

The dumpcap documentation points out that it runs as a secondary process,
as such I was wondering whether the multi-process limitations such as the
requirement to disable ASLR on both processes, and more importantly the
limitations regarding the use of librte_hash, also apply when using the
dumpcap tool?

Thanks!

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Re: Multi-process limitations when using the dumpcap tool

[Stephen Hemminger]

On Fri, 3 Mar 2023 12:33:20 +0200
Isaac Boukris <iboukris@gmail.com> wrote:

> Hello,
> 
> The dumpcap documentation points out that it runs as a secondary process,
> as such I was wondering whether the multi-process limitations such as the
> requirement to disable ASLR on both processes, and more importantly the
> limitations regarding the use of librte_hash, also apply when using the
> dumpcap tool?
> 
> Thanks!

Dumpcap is passive and have not heard of any problems related to ASLR.

Re: Multi-process limitations when using the dumpcap tool

[Isaac Boukris]

On Sat, Mar 4, 2023 at 12:18 AM Stephen Hemminger
<stephen@networkplumber.org> wrote:
>
> On Fri, 3 Mar 2023 12:33:20 +0200
> Isaac Boukris <iboukris@gmail.com> wrote:
>
> > Hello,
> >
> > The dumpcap documentation points out that it runs as a secondary process,
> > as such I was wondering whether the multi-process limitations such as the
> > requirement to disable ASLR on both processes, and more importantly the
> > limitations regarding the use of librte_hash, also apply when using the
> > dumpcap tool?
> >
> > Thanks!
>
> Dumpcap is passive and have not heard of any problems related to ASLR.

I realized upon sending that the librte_hash limitation is likely only
when sharing tables between processes, I guess that's what you mean by
passive.

Thanks!

Re: Multi-process limitations when using the dumpcap tool

[Stephen Hemminger]

On Sat, 4 Mar 2023 00:37:53 +0200
Isaac Boukris <iboukris@gmail.com> wrote:

> On Sat, Mar 4, 2023 at 12:18 AM Stephen Hemminger
> <stephen@networkplumber.org> wrote:
> >
> > On Fri, 3 Mar 2023 12:33:20 +0200
> > Isaac Boukris <iboukris@gmail.com> wrote:
> >  
> > > Hello,
> > >
> > > The dumpcap documentation points out that it runs as a secondary process,
> > > as such I was wondering whether the multi-process limitations such as the
> > > requirement to disable ASLR on both processes, and more importantly the
> > > limitations regarding the use of librte_hash, also apply when using the
> > > dumpcap tool?
> > >
> > > Thanks!  
> >
> > Dumpcap is passive and have not heard of any problems related to ASLR.  
> 
> I realized upon sending that the librte_hash limitation is likely only
> when sharing tables between processes, I guess that's what you mean by
> passive.
> 
> Thanks!

It is more about where data could be allocated. The only allocation in dumpcap
or pdump that matters is the associated mbuf pool. This is allocated out of
normal hugepage memory which is pinned in both primary/secondary at same address.