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From: Pavel Begunkov <[email protected]>
To: Mina Almasry <[email protected]>, David Wei <[email protected]>
Cc: [email protected], [email protected],
	Jens Axboe <[email protected]>, Jakub Kicinski <[email protected]>,
	Paolo Abeni <[email protected]>,
	"David S. Miller" <[email protected]>,
	Eric Dumazet <[email protected]>,
	Jesper Dangaard Brouer <[email protected]>,
	David Ahern <[email protected]>
Subject: Re: [RFC PATCH v3 02/20] tcp: don't allow non-devmem originated ppiov
Date: Wed, 20 Dec 2023 01:29:08 +0000	[thread overview]
Message-ID: <[email protected]> (raw)
In-Reply-To: <CAHS8izO0ADnYqKczEkfNts2VLDfiYEkQ=AzJ-xzb+Kh2ZpFjbg@mail.gmail.com>

On 12/19/23 23:24, Mina Almasry wrote:
> On Tue, Dec 19, 2023 at 1:04 PM David Wei <[email protected]> wrote:
>>
>> From: Pavel Begunkov <[email protected]>
>>
>> NOT FOR UPSTREAM
>>
>> There will be more users of struct page_pool_iov, and ppiovs from one
>> subsystem must not be used by another. That should never happen for any
>> sane application, but we need to enforce it in case of bufs and/or
>> malicious users.
>>
>> Signed-off-by: Pavel Begunkov <[email protected]>
>> Signed-off-by: David Wei <[email protected]>
>> ---
>>   net/ipv4/tcp.c | 7 +++++++
>>   1 file changed, 7 insertions(+)
>>
>> diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
>> index 33a8bb63fbf5..9c6b18eebb5b 100644
>> --- a/net/ipv4/tcp.c
>> +++ b/net/ipv4/tcp.c
>> @@ -2384,6 +2384,13 @@ static int tcp_recvmsg_devmem(const struct sock *sk, const struct sk_buff *skb,
>>                          }
>>
>>                          ppiov = skb_frag_page_pool_iov(frag);
>> +
>> +                       /* Disallow non devmem owned buffers */
>> +                       if (ppiov->pp->p.memory_provider != PP_MP_DMABUF_DEVMEM) {
>> +                               err = -ENODEV;
>> +                               goto out;
>> +                       }
>> +
> 
> Instead of this, I maybe recommend modifying the skb->dmabuf flag? My
> mental model is that flag means all the frags in the skb are

That's a good point, we need to separate them, and I have it in my
todo list.

> specifically dmabuf, not general ppiovs or net_iovs. Is it possible to
> add skb->io_uring or something?

->io_uring flag is not feasible, converting ->devmem into a type
{page,devmem,iouring} is better but not great either.

> If that bloats the skb headers, then maybe we need another place to
> put this flag. Maybe the [page_pool|net]_iov should declare whether
> it's dmabuf or otherwise, and we can check frag[0] and assume all

ppiov->pp should be enough, either not mixing buffers from different
pools or comparing pp->ops or some pp->type.

> frags are the same as frag0.

I think I like this one the most. I think David Ahern mentioned
before, but would be nice having it on per frag basis and kill
->devmem flag. That would still stop collapsing if frags are
from different pools or so.

> But IMO the page pool internals should not leak into the
> implementation of generic tcp stack functions.

-- 
Pavel Begunkov

  reply	other threads:[~2023-12-20  1:34 UTC|newest]

Thread overview: 50+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-12-19 21:03 [RFC PATCH v3 00/20] Zero copy Rx using io_uring David Wei
2023-12-19 21:03 ` [RFC PATCH v3 01/20] net: page_pool: add ppiov mangling helper David Wei
2023-12-19 23:22   ` Mina Almasry
2023-12-19 23:59     ` Pavel Begunkov
2023-12-19 21:03 ` [RFC PATCH v3 02/20] tcp: don't allow non-devmem originated ppiov David Wei
2023-12-19 23:24   ` Mina Almasry
2023-12-20  1:29     ` Pavel Begunkov [this message]
2024-01-02 16:11       ` Mina Almasry
2023-12-19 21:03 ` [RFC PATCH v3 03/20] net: page pool: rework ppiov life cycle David Wei
2023-12-19 23:35   ` Mina Almasry
2023-12-20  0:49     ` Pavel Begunkov
2023-12-19 21:03 ` [RFC PATCH v3 04/20] net: enable napi_pp_put_page for ppiov David Wei
2023-12-19 21:03 ` [RFC PATCH v3 05/20] net: page_pool: add ->scrub mem provider callback David Wei
2023-12-19 21:03 ` [RFC PATCH v3 06/20] io_uring: separate header for exported net bits David Wei
2023-12-20 16:01   ` Jens Axboe
2023-12-19 21:03 ` [RFC PATCH v3 07/20] io_uring: add interface queue David Wei
2023-12-20 16:13   ` Jens Axboe
2023-12-20 16:23     ` Pavel Begunkov
2023-12-21  1:44     ` David Wei
2023-12-21 17:57   ` Willem de Bruijn
2023-12-30 16:25     ` Pavel Begunkov
2023-12-31 22:25       ` Willem de Bruijn
2023-12-19 21:03 ` [RFC PATCH v3 08/20] io_uring: add mmap support for shared ifq ringbuffers David Wei
2023-12-20 16:13   ` Jens Axboe
2023-12-19 21:03 ` [RFC PATCH v3 09/20] netdev: add XDP_SETUP_ZC_RX command David Wei
2023-12-19 21:03 ` [RFC PATCH v3 10/20] io_uring: setup ZC for an Rx queue when registering an ifq David Wei
2023-12-20 16:06   ` Jens Axboe
2023-12-20 16:24     ` Pavel Begunkov
2023-12-19 21:03 ` [RFC PATCH v3 11/20] io_uring/zcrx: implement socket registration David Wei
2023-12-19 21:03 ` [RFC PATCH v3 12/20] io_uring: add ZC buf and pool David Wei
2023-12-19 21:03 ` [RFC PATCH v3 13/20] io_uring: implement pp memory provider for zc rx David Wei
2023-12-19 23:44   ` Mina Almasry
2023-12-20  0:39     ` Pavel Begunkov
2023-12-21 19:36   ` Pavel Begunkov
2023-12-19 21:03 ` [RFC PATCH v3 14/20] net: page pool: add io_uring memory provider David Wei
2023-12-19 23:39   ` Mina Almasry
2023-12-20  0:04     ` Pavel Begunkov
2023-12-19 21:03 ` [RFC PATCH v3 15/20] io_uring: add io_recvzc request David Wei
2023-12-20 16:27   ` Jens Axboe
2023-12-20 17:04     ` Pavel Begunkov
2023-12-20 18:09       ` Jens Axboe
2023-12-21 18:59         ` Pavel Begunkov
2023-12-21 21:32           ` Jens Axboe
2023-12-30 21:15             ` Pavel Begunkov
2023-12-19 21:03 ` [RFC PATCH v3 16/20] net: execute custom callback from napi David Wei
2023-12-19 21:03 ` [RFC PATCH v3 17/20] io_uring/zcrx: add copy fallback David Wei
2023-12-19 21:03 ` [RFC PATCH v3 18/20] veth: add support for io_uring zc rx David Wei
2023-12-19 21:03 ` [RFC PATCH v3 19/20] net: page pool: generalise ppiov dma address get David Wei
2023-12-21 19:51   ` Mina Almasry
2023-12-19 21:03 ` [RFC PATCH v3 20/20] bnxt: enable io_uring zc page pool David Wei

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