From: Phil Sutter <phil@nwl.cc>
To: Florian Westphal <fw@strlen.de>
Cc: Pablo Neira Ayuso <pablo@netfilter.org>, netfilter-devel@vger.kernel.org
Subject: Re: [nf PATCH v2 8/8] netfilter: nf_tables: Add locking for NFT_MSG_GETSETELEM_RESET requests
Date: Fri, 29 Sep 2023 13:45:52 +0200 [thread overview]
Message-ID: <ZRa48F2N2MxbhXSi@orbyte.nwl.cc> (raw)
In-Reply-To: <20230929113043.GF28176@breakpoint.cc>
On Fri, Sep 29, 2023 at 01:30:43PM +0200, Florian Westphal wrote:
> Phil Sutter <phil@nwl.cc> wrote:
> > On Thu, Sep 28, 2023 at 10:07:51PM +0200, Florian Westphal wrote:
> > > I don't really like it though because misbehaving userspace
> > > can lock out writers.
> >
> > Make them inactive and free only after the dump is done? IIUC,
> > nft_active_genmask() will return true again though after the second
> > update, right?
>
> Yes, however, in case of update and 'reset dump', we'll set the
> NLM_F_DUMP_INTR flag, so userspace would restart the dump.
>
> AFAIU, this means the original values of 'already-reset' counters
> are lost given nft will restart the 'reset dump'.
>
> Alternative is make nft not restart if reset-dump was requested,
> but in that case the dump can be incomplete.
Modification of the data being dump-reset is unsolvable anyway, unless
we can undo the reset. Not having to return EINTR for unrelated
modifications would help already, though may just be yet another
half-ass solution.
I'd honestly just document the unreliability of 'reset rules' and point
at 'reset rule' for a safe variant. (Assuming the non-dump path is
actually safe?!)
Cheers, Phil
next prev parent reply other threads:[~2023-09-29 11:46 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-09-28 16:52 [nf PATCH v2 0/8] Introduce locking for reset requests Phil Sutter
2023-09-28 16:52 ` [nf PATCH v2 1/8] netfilter: nf_tables: Don't allocate nft_rule_dump_ctx Phil Sutter
2023-09-28 18:49 ` Pablo Neira Ayuso
2023-09-29 10:15 ` Phil Sutter
2023-09-28 19:00 ` Florian Westphal
2023-09-29 10:13 ` Phil Sutter
2023-09-28 16:52 ` [nf PATCH v2 2/8] netfilter: nf_tables: Introduce nf_tables_getrule_single() Phil Sutter
2023-09-28 16:52 ` [nf PATCH v2 3/8] netfilter: nf_tables: Add locking for NFT_MSG_GETRULE_RESET requests Phil Sutter
2023-09-28 16:52 ` [nf PATCH v2 4/8] netfilter: nf_tables: Introduce struct nft_obj_dump_ctx Phil Sutter
2023-09-28 16:52 ` [nf PATCH v2 5/8] netfilter: nf_tables: Introduce nf_tables_getobj_single Phil Sutter
2023-09-28 16:52 ` [nf PATCH v2 6/8] netfilter: nf_tables: Add locking for NFT_MSG_GETOBJ_RESET requests Phil Sutter
2023-09-28 16:52 ` [nf PATCH v2 7/8] netfilter: nf_tables: Pass reset bit in nft_set_dump_ctx Phil Sutter
2023-09-28 18:53 ` Pablo Neira Ayuso
2023-09-29 10:08 ` Phil Sutter
2023-09-29 10:15 ` Pablo Neira Ayuso
2023-09-29 10:18 ` Phil Sutter
2023-09-29 10:56 ` Pablo Neira Ayuso
2023-09-29 11:12 ` Phil Sutter
2023-09-28 16:52 ` [nf PATCH v2 8/8] netfilter: nf_tables: Add locking for NFT_MSG_GETSETELEM_RESET requests Phil Sutter
2023-09-28 17:46 ` Florian Westphal
2023-09-28 18:47 ` Pablo Neira Ayuso
2023-09-28 18:57 ` Florian Westphal
2023-09-28 19:04 ` Pablo Neira Ayuso
2023-09-28 19:21 ` Florian Westphal
2023-09-28 20:07 ` Florian Westphal
2023-09-29 11:25 ` Phil Sutter
2023-09-29 11:30 ` Florian Westphal
2023-09-29 11:45 ` Phil Sutter [this message]
2023-09-28 19:39 ` Jozsef Kadlecsik
2023-09-28 20:09 ` Florian Westphal
2023-09-28 20:25 ` Jozsef Kadlecsik
2023-09-29 11:03 ` Phil Sutter
2023-09-28 18:51 ` Pablo Neira Ayuso
2023-09-29 10:28 ` Phil Sutter
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