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Date: Tue, 5 Dec 2023 15:17:10 +0100
From: Pablo Neira Ayuso <pablo@netfilter.org>
To: Phil Sutter <phil@nwl.cc>, Florian Westphal <fw@strlen.de>,
	netfilter-devel@vger.kernel.org
Subject: Re: [PATCH nf] netfilter: nf_tables: validate family when
 identifying table via handle
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On Tue, Dec 05, 2023 at 02:10:40PM +0100, Phil Sutter wrote:
> On Mon, Dec 04, 2023 at 03:05:45PM +0100, Pablo Neira Ayuso wrote:
> > On Mon, Dec 04, 2023 at 03:03:41PM +0100, Florian Westphal wrote:
> > > Pablo Neira Ayuso <pablo@netfilter.org> wrote:
> > > > Validate table family when looking up for it via NFTA_TABLE_HANDLE.
> > > > 
> > > > Reported-by: Xingyuan Mo <hdthky0@gmail.com>
> > > > Fixes: 3ecbfd65f50e ("netfilter: nf_tables: allocate handle and delete objects via handle")
> > > > Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
> > > > ---
> > > >  net/netfilter/nf_tables_api.c | 5 +++--
> > > >  1 file changed, 3 insertions(+), 2 deletions(-)
> > > 
> > > This changes behaviour, before this change you can do
> > > 
> > > nft delete table handle 42
> > > 
> > > and it will delete the table with handle 42.
> > 
> > Default family is 'ip' if not specified, that is inconsistent with
> > other objects?
> 
> I would say the table's handle is a complete replacement of its family
> and name, also because it's pernet-unique.

Only tables and newer kernels >= 5.15 -stable, yes.

> Though looking at the docs, we surprisingly claim to support:
> 
> | delete table [<family>] handle <handle>

For consistency with existing objects, yes.

> So either we accept user space is wrong and the family value doesn't
> matter there or we artificially limit table lookup by handle to the
> given family. IMHO either way kind of breaks user space.
>
> Off-topic here, but I would prefer for all handles to be pernet-unique
> so user space could 'nft delete <whatever> handle <handle>'. Why was a
> table-unique value chosen here?