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Subject: Re: [PATCH] usbnet: ipheth: fix connectivity with iOS 14
To:     Yves-Alexis Perez <corsac@corsac.net>,
        "David S. Miller" <davem@davemloft.net>,
        Jakub Kicinski <kuba@kernel.org>,
        Martin Habets <mhabets@solarflare.com>,
        Luc Van Oostenryck <luc.vanoostenryck@gmail.com>,
        Shannon Nelson <snelson@pensando.io>,
        "Michael S. Tsirkin" <mst@redhat.com>, linux-usb@vger.kernel.org,
        netdev@vger.kernel.org, linux-kernel@vger.kernel.org
Cc:     Matti Vuorela <matti.vuorela@bitfactor.fi>, stable@vger.kernel.org
References: <CAAn0qaXmysJ9vx3ZEMkViv_B19ju-_ExN8Yn_uSefxpjS6g4Lw@mail.gmail.com>
 <20201119172439.94988-1-corsac@corsac.net>
From:   Sergei Shtylyov <sergei.shtylyov@gmail.com>
Organization: Brain-dead Software
Message-ID: <22d938ab-babc-815a-f635-5025e871cf62@gmail.com>
Date:   Fri, 20 Nov 2020 12:15:24 +0300
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Hello!

On 19.11.2020 20:24, Yves-Alexis Perez wrote:

> Starting with iOS 14 released in September 2020, connectivity using the
> personal hotspot USB tethering function of iOS devices is broken.
> 
> Communication between the host and the device (for example ICMP traffic
> or DNS resolution using the DNS service running in the device itself)
> works fine, but communication to endpoints further away doesn't work.
> 
> Investigation on the matter shows that UDP and ICMP traffic from the
                                         ^ "no" missing?

> tethered host is reaching the Internet at all. For TCP traffic there are
> exchanges between tethered host and server but packets are modified in
> transit leading to impossible communication.
> 
> After some trials Matti Vuorela discovered that reducing the URB buffer
> size by two bytes restored the previous behavior. While a better
> solution might exist to fix the issue, since the protocol is not
> publicly documented and considering the small size of the fix, let's do
> that.
> 
> Tested-by: Matti Vuorela <matti.vuorela@bitfactor.fi>
> Signed-off-by: Yves-Alexis Perez <corsac@corsac.net>
> Link: https://lore.kernel.org/linux-usb/CAAn0qaXmysJ9vx3ZEMkViv_B19ju-_ExN8Yn_uSefxpjS6g4Lw@mail.gmail.com/
> Link: https://github.com/libimobiledevice/libimobiledevice/issues/1038
> Cc: stable@vger.kernel.org
[...]

MBR, Sergei