Non-standard requests can encode the actual interface number in a
non-standard way. For example composite_setup() assumes
that it is w_index && 0xFF, but the printer function encodes the interface
number in a context-dependet way (either w_index or w_index >> 8).
This can lead to such requests being directed to wrong functions.
This patch adds req_match() method to usb_function. Its purpose is to
verify that a given request can be handled by a given function.
If any function within a configuration provides the method and it returns
true, then it is assumed that the right function is found.
If a function uses req_match(), it should try as hard as possible to
determine if the request is meant for it.
If no functions in a configuration provide req_match or none of them
returns true, then fall back to the usual approach.
Signed-off-by: Andrzej Pietrasiewicz <andrzej.p@xxxxxxxxxxx>
---
drivers/usb/gadget/composite.c | 7 ++++++-
include/linux/usb/composite.h | 3 +++
2 files changed, 9 insertions(+), 1 deletion(-)
diff --git a/drivers/usb/gadget/composite.c b/drivers/usb/gadget/composite.c
index 9fb9231..07cee80 100644
--- a/drivers/usb/gadget/composite.c
+++ b/drivers/usb/gadget/composite.c
@@ -1758,6 +1758,11 @@ unknown:
* take such requests too, if that's ever needed: to work
* in config 0, etc.
*/
+ list_for_each_entry(f, &cdev->config->functions, list)
+ if (f->req_match && f->req_match(f, ctrl))
+ break;
+ if (&f->list != &cdev->config->functions)
+ goto try_fun_setup;
switch (ctrl->bRequestType & USB_RECIP_MASK) {
case USB_RECIP_INTERFACE:
if (!cdev->config || intf >= MAX_CONFIG_INTERFACES)
@@ -1775,7 +1780,7 @@ unknown:
f = NULL;
break;
}
-
+try_fun_setup:
if (f && f->setup)
value = f->setup(f, ctrl);
else {
diff --git a/include/linux/usb/composite.h b/include/linux/usb/composite.h
index 3d87def..51f477a 100644
--- a/include/linux/usb/composite.h
+++ b/include/linux/usb/composite.h
@@ -147,6 +147,7 @@ struct usb_os_desc_table {
* then only altsetting zero is supported.
* @disable: (REQUIRED) Indicates the function should be disabled. Reasons
* include host resetting or reconfiguring the gadget, and disconnection.
+ * @req_match: Tests if a given class request can be handled by this function.
* @setup: Used for interface-specific control requests.
* @suspend: Notifies functions when the host stops sending USB traffic.
* @resume: Notifies functions when the host restarts USB traffic.
@@ -211,6 +212,8 @@ struct usb_function {
int (*get_alt)(struct usb_function *,
unsigned interface);
void (*disable)(struct usb_function *);
+ bool (*req_match)(struct usb_function *,
+ const struct usb_ctrlrequest *);
int (*setup)(struct usb_function *,
const struct usb_ctrlrequest *);
void (*suspend)(struct usb_function *);
--
1.9.1
--
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