[openwrt/openwrt] generic: ipeth: fix iOS 14 tethering

[LEDE Commits]

blocktrron pushed a commit to openwrt/openwrt.git, branch openwrt-19.07:
https://git.openwrt.org/d0b8be75ff248b4cda009a6c1ce72eb0072c6f82

commit d0b8be75ff248b4cda009a6c1ce72eb0072c6f82
Author: David Bauer <mail at david-bauer.net>
AuthorDate: Sun Nov 29 19:14:05 2020 +0100

    generic: ipeth: fix iOS 14 tethering
    
    This fixes tethering with devices using iOS 14. Prior to this patch,
    connections to remote endpoints were not possible while data transfers
    between the OpenWrt device and the iOS endpoints worked fine.
    
    Signed-off-by: David Bauer <mail at david-bauer.net>
    (cherry picked from commit f64496f30f2ef97124dc4e13a48ee0de9d51832e)
---
 ...usbnet-ipeth-fix-connectivity-with-ios-14.patch | 44 ++++++++++++++++++++++
 1 file changed, 44 insertions(+)

diff --git a/target/linux/generic/backport-4.14/315-v5.10-usbnet-ipeth-fix-connectivity-with-ios-14.patch b/target/linux/generic/backport-4.14/315-v5.10-usbnet-ipeth-fix-connectivity-with-ios-14.patch
new file mode 100644
index 0000000000..aebc8752b4
--- /dev/null
+++ b/target/linux/generic/backport-4.14/315-v5.10-usbnet-ipeth-fix-connectivity-with-ios-14.patch
@@ -0,0 +1,44 @@
+From:   Yves-Alexis Perez <corsac at corsac.net>
+Subject: [PATCH] usbnet: ipheth: fix connectivity with iOS 14
+Date:   Thu, 19 Nov 2020 18:24:39 +0100
+Archived-At: <https://lore.kernel.org/stable/20201119172439.94988-1-corsac@corsac.net/>
+List-Post: <mailto:stable at vger.kernel.org>
+
+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
+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 at bitfactor.fi>
+Signed-off-by: Yves-Alexis Perez <corsac at 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 at vger.kernel.org
+---
+ drivers/net/usb/ipheth.c | 2 +-
+ 1 file changed, 1 insertion(+), 1 deletion(-)
+
+--- a/drivers/net/usb/ipheth.c
++++ b/drivers/net/usb/ipheth.c
+@@ -70,7 +70,7 @@
+ #define IPHETH_USBINTF_SUBCLASS 253
+ #define IPHETH_USBINTF_PROTO    1
+ 
+-#define IPHETH_BUF_SIZE         1516
++#define IPHETH_BUF_SIZE         1514
+ #define IPHETH_IP_ALIGN		2	/* padding at front of URB */
+ #define IPHETH_TX_TIMEOUT       (5 * HZ)
+