6.6-stable review patch. If anyone has any objections, please let me know.
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From: Foster Snowhill forst@pen.gy
commit be154b598fa54136e2be17d6dd13c8a8bc0078ce upstream.
Clarify that the "NCM" implementation in `ipheth` is very limited, as iOS devices aren't compatible with the CDC NCM specification in regular tethering mode.
For a standards-compliant implementation, one shall turn to the `cdc_ncm` module.
Cc: stable@vger.kernel.org # 6.5.x Signed-off-by: Foster Snowhill forst@pen.gy Reviewed-by: Jakub Kicinski kuba@kernel.org Signed-off-by: Paolo Abeni pabeni@redhat.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/net/usb/ipheth.c | 8 ++++++++ 1 file changed, 8 insertions(+)
diff --git a/drivers/net/usb/ipheth.c b/drivers/net/usb/ipheth.c index 5347cd7e295b..a19789b57190 100644 --- a/drivers/net/usb/ipheth.c +++ b/drivers/net/usb/ipheth.c @@ -218,6 +218,14 @@ static int ipheth_rcvbulk_callback_legacy(struct urb *urb) return ipheth_consume_skb(buf, len, dev); }
+/* In "NCM mode", the iOS device encapsulates RX (phone->computer) traffic + * in NCM Transfer Blocks (similarly to CDC NCM). However, unlike reverse + * tethering (handled by the `cdc_ncm` driver), regular tethering is not + * compliant with the CDC NCM spec, as the device is missing the necessary + * descriptors, and TX (computer->phone) traffic is not encapsulated + * at all. Thus `ipheth` implements a very limited subset of the spec with + * the sole purpose of parsing RX URBs. + */ static int ipheth_rcvbulk_callback_ncm(struct urb *urb) { struct usb_cdc_ncm_nth16 *ncmh;