Input: uinput - allow injecting event times

Currently, uinput doesn't use the input_set_timestamp API, so any
event injected using uinput is not accurately timestamped in terms of
measuring when the actual event happened. Hence, call the
input_set_timestamp API from uinput in order to provide a more
accurate sense of time for the event. Propagate only the timestamps
which are a) positive, b) within a pre-defined offset (10 secs) from
the current time, and c) not in the future.

Signed-off-by: Biswarup Pal <biswarupp@google.com>
Reviewed-by: Peter Hutterer <peter.hutterer@who-t.net>
Reviewed-by: Siarhei Vishniakou <svv@google.com>
Link: https://lore.kernel.org/r/20230427000152.1407471-1-biswarupp@google.com
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

diff --git a/drivers/input/misc/uinput.c b/drivers/input/misc/uinput.c
index f2593133e5247a8fbc6cebfc296a2aedeb0c87ff..d98212d55108c7e394c669d08f6ea86859e1dfe9 100644 (file)
--- a/drivers/input/misc/uinput.c
+++ b/drivers/input/misc/uinput.c
@@ -33,6 +33,7 @@
 #define UINPUT_NAME            "uinput"
 #define UINPUT_BUFFER_SIZE     16
 #define UINPUT_NUM_REQUESTS    16
+#define UINPUT_TIMESTAMP_ALLOWED_OFFSET_SECS 10
 
 enum uinput_state { UIST_NEW_DEVICE, UIST_SETUP_COMPLETE, UIST_CREATED };
 
@@ -569,11 +570,40 @@ static int uinput_setup_device_legacy(struct uinput_device *udev,
        return retval;
 }
 
+/*
+ * Returns true if the given timestamp is valid (i.e., if all the following
+ * conditions are satisfied), false otherwise.
+ * 1) given timestamp is positive
+ * 2) it's within the allowed offset before the current time
+ * 3) it's not in the future
+ */
+static bool is_valid_timestamp(const ktime_t timestamp)
+{
+       ktime_t zero_time;
+       ktime_t current_time;
+       ktime_t min_time;
+       ktime_t offset;
+
+       zero_time = ktime_set(0, 0);
+       if (ktime_compare(zero_time, timestamp) >= 0)
+               return false;
+
+       current_time = ktime_get();
+       offset = ktime_set(UINPUT_TIMESTAMP_ALLOWED_OFFSET_SECS, 0);
+       min_time = ktime_sub(current_time, offset);
+
+       if (ktime_after(min_time, timestamp) || ktime_after(timestamp, current_time))
+               return false;
+
+       return true;
+}
+
 static ssize_t uinput_inject_events(struct uinput_device *udev,
                                    const char __user *buffer, size_t count)
 {
        struct input_event ev;
        size_t bytes = 0;
+       ktime_t timestamp;
 
        if (count != 0 && count < input_event_size())
                return -EINVAL;
@@ -588,6 +618,10 @@ static ssize_t uinput_inject_events(struct uinput_device *udev,
                if (input_event_from_user(buffer + bytes, &ev))
                        return -EFAULT;
 
+               timestamp = ktime_set(ev.input_event_sec, ev.input_event_usec * NSEC_PER_USEC);
+               if (is_valid_timestamp(timestamp))
+                       input_set_timestamp(udev->dev, timestamp);
+
                input_event(udev->dev, ev.type, ev.code, ev.value);
                bytes += input_event_size();
                cond_resched();