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([2a0d:3344:5521:6b10:58fd:68f:7756:389d]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-493e0ebf593sm39085795e9.0.2026.07.07.01.10.11 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 07 Jul 2026 01:10:12 -0700 (PDT) Message-ID: <1f4c7607-007d-49e8-b3bc-d1fd8034c570@redhat.com> Date: Tue, 7 Jul 2026 10:10:11 +0200 Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH net] net/tls: Consume empty data records in tls_sw_read_sock() To: Sabrina Dubroca , Chuck Lever Cc: john.fastabend@gmail.com, Jakub Kicinski , davem@davemloft.net, edumazet@google.com, Simon Horman , netdev@vger.kernel.org References: <20260630191551.875664-1-cel@kernel.org> <0a03d16e-d4ce-422d-9492-3e31d910d8e5@app.fastmail.com> Content-Language: en-US From: Paolo Abeni In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 7/7/26 9:58 AM, Sabrina Dubroca wrote: > 2026-07-06, 15:16:21 -0400, Chuck Lever wrote: >> On Thu, Jul 2, 2026, at 5:50 PM, Sabrina Dubroca wrote: >>> 2026-07-02, 15:52:49 -0400, Chuck Lever wrote: >>>> >>>> >>>> On Thu, Jul 2, 2026, at 2:05 PM, Sabrina Dubroca wrote: >>>>> 2026-06-30, 15:15:51 -0400, Chuck Lever wrote: >>>>>> A peer may send a zero-length TLS application_data record; TLS 1.3 >>>>>> explicitly permits these as a traffic-analysis countermeasure (RFC >>>>>> 8446, Section 5.1). After decryption such a record has full_len == >>>>>> 0. tls_sw_read_sock() hands it to the read_actor, which has no >>>>>> payload to consume and returns zero. The loop treats a zero return >>>>>> as backpressure (used <= 0), requeues the skb at the head of >>>>>> rx_list, and stops. rx_list is serviced head-first on the next >>>>>> call, so the empty record is dequeued, fails the same way, and is >>>>>> requeued again; every later record on the connection is blocked >>>>>> behind it. >>>>>> >>>>>> tls_sw_recvmsg() does not stall on this: a zero-length data record >>>>>> copies nothing and falls through to consume_skb(). Mirror that in >>>>>> the read_sock() path by recognizing an empty data record before >>>>>> the actor runs, consuming it, and continuing. >>>>>> >>>>>> Fixes: 662fbcec32f4 ("net/tls: implement ->read_sock()") >>>>>> Signed-off-by: Chuck Lever >>>>>> --- >>>>>> net/tls/tls_sw.c | 11 +++++++++++ >>>>>> 1 file changed, 11 insertions(+) >>>>> >>>>> Reviewed-by: Sabrina Dubroca >>>>> >>>>> I think tls_sw_splice_read() suffers from a similar issue (returning 0 >>>>> even though more data may be available). Sashiko agrees, and also >>>>> found a few more pre-existing issues. >>>> >>>> Do you want a v2 series with those issues addressed? >>> >>> I'd be ok with this patch going in on its own, and the other issues >>> being addressed separately. If you have time to look into those, >>> that'd be great. >> >> patchwork shows this patch continues to be marked as "New". Is there >> something I need to do to help move it forward? > > I don't think there's anything blocking it other than the length of > the maintainers' backlog. As noted yday: https://lore.kernel.org/netdev/c0cd72bd-6298-47a4-82a3-c43811c98063@redhat.com/ current patch processing capacity is limited. I'm processing this one right now. /P