wlr_seat: Fix edge cases with serial validation

This commit is contained in:
Manuel Stoeckl 2019-06-29 09:15:23 -04:00 committed by Drew DeVault
parent edb30a6828
commit ded441ffd5
4 changed files with 45 additions and 29 deletions

View file

@ -21,25 +21,12 @@ struct wlr_serial_range {
uint32_t min_incl;
uint32_t max_incl;
};
struct wlr_serial_ringset {
struct wlr_serial_range data[WLR_SERIAL_RINGSET_SIZE];
int end;
int count;
};
/**
* Add a new serial number to the set. The number must be larger than
* all other values already added
*/
void wlr_serial_add(struct wlr_serial_ringset *set, uint32_t serial);
/**
* Return false if the serial number is definitely not in the set, true
* otherwise.
*/
bool wlr_serial_maybe_valid(struct wlr_serial_ringset *set, uint32_t serial);
/**
* Contains state for a single client's bound wl_seat resource and can be used
* to issue input events to that client. The lifetime of these objects is
@ -62,6 +49,7 @@ struct wlr_seat_client {
} events;
// set of serials which were sent to the client on this seat
// for use by wlr_seat_client_{next_serial,validate_event_serial}
struct wlr_serial_ringset serials;
};
@ -652,10 +640,24 @@ bool wlr_seat_validate_touch_grab_serial(struct wlr_seat *seat,
/**
* Return a new serial (from wl_display_serial_next()) for the client, and
* update the seat client's set of valid serials. Use this for all input
* events.
* events; otherwise wlr_seat_client_validate_event_serial() may fail when
* handed a correctly functioning client's request serials.
*/
uint32_t wlr_seat_client_next_serial(struct wlr_seat_client *client);
/**
* Return true if the serial number could have been produced by
* wlr_seat_client_next_serial() and is "older" (by less than UINT32_MAX/2) than
* the current display serial value.
*
* This function should have no false negatives, and the only false positive
* responses allowed are for elements that are still "older" than the current
* display serial value and also older than all serial values remaining in
* the seat client's serial ring buffer, if that buffer is also full.
*/
bool wlr_seat_client_validate_event_serial(struct wlr_seat_client *client,
uint32_t serial);
/**
* Get a seat client from a seat resource. Returns NULL if inert.
*/

View file

@ -144,7 +144,7 @@ void seat_client_send_selection(struct wlr_seat_client *seat_client) {
void wlr_seat_request_set_selection(struct wlr_seat *seat,
struct wlr_seat_client *client,
struct wlr_data_source *source, uint32_t serial) {
if (client && !wlr_serial_maybe_valid(&client->serials, serial)) {
if (client && !wlr_seat_client_validate_event_serial(client, serial)) {
wlr_log(WLR_DEBUG, "Rejecting set_selection request, "
"serial %"PRIu32" was never given to client", serial);
return;

View file

@ -142,6 +142,9 @@ static void seat_handle_bind(struct wl_client *client, void *_wlr_seat,
wl_signal_init(&seat_client->events.destroy);
wl_list_insert(&wlr_seat->clients, &seat_client->link);
// ensure first entry will have index zero
seat_client->serials.end = WLR_SERIAL_RINGSET_SIZE - 1;
}
wl_resource_set_implementation(wl_resource, &seat_impl,
@ -371,11 +374,13 @@ bool wlr_seat_validate_grab_serial(struct wlr_seat *seat, uint32_t serial) {
return true;
}
void wlr_serial_add(struct wlr_serial_ringset *set, uint32_t serial) {
uint32_t wlr_seat_client_next_serial(struct wlr_seat_client *client) {
uint32_t serial = wl_display_next_serial(wl_client_get_display(client->client));
struct wlr_serial_ringset *set = &client->serials;
if (set->count == 0 || set->data[set->end].max_incl + 1 != serial) {
set->count++;
if (set->count > WLR_SERIAL_RINGSET_SIZE) {
set->count = WLR_SERIAL_RINGSET_SIZE;
if (set->count < WLR_SERIAL_RINGSET_SIZE) {
set->count++;
}
set->end = (set->end + 1) % WLR_SERIAL_RINGSET_SIZE;
set->data[set->end].min_incl = serial;
@ -383,23 +388,32 @@ void wlr_serial_add(struct wlr_serial_ringset *set, uint32_t serial) {
} else {
set->data[set->end].max_incl = serial;
}
return serial;
}
bool wlr_serial_maybe_valid(struct wlr_serial_ringset *set, uint32_t serial) {
bool wlr_seat_client_validate_event_serial(struct wlr_seat_client *client, uint32_t serial) {
uint32_t cur = wl_display_get_serial(wl_client_get_display(client->client));
struct wlr_serial_ringset *set = &client->serials;
uint32_t rev_dist = cur - serial;
if (rev_dist >= UINT32_MAX / 2) {
// serial is closer to being 'newer' instead of 'older' than
// the current serial, so it's either invalid or incredibly old
return false;
}
for (int i = 0; i < set->count; i++) {
int j = (set->end - i + WLR_SERIAL_RINGSET_SIZE) % WLR_SERIAL_RINGSET_SIZE;
if (set->data[j].max_incl - serial > UINT32_MAX / 2) {
if (rev_dist < cur - set->data[j].max_incl) {
return false;
}
if (serial - set->data[j].min_incl <= UINT32_MAX / 2) {
if (rev_dist <= cur - set->data[j].min_incl) {
return true;
}
}
return true;
}
uint32_t wlr_seat_client_next_serial(struct wlr_seat_client *client) {
uint32_t serial = wl_display_next_serial(wl_client_get_display(client->client));
wlr_serial_add(&client->serials, serial);
return serial;
// Iff the set is full, then `rev_dist` is large enough that serial
// could already have been recycled out of the set.
return set->count == WLR_SERIAL_RINGSET_SIZE;
}

View file

@ -44,7 +44,7 @@ void wlr_primary_selection_source_send(
void wlr_seat_request_set_primary_selection(struct wlr_seat *seat,
struct wlr_seat_client *client,
struct wlr_primary_selection_source *source, uint32_t serial) {
if (client && !wlr_serial_maybe_valid(&client->serials, serial)) {
if (client && !wlr_seat_client_validate_event_serial(client, serial)) {
wlr_log(WLR_DEBUG, "Rejecting set_primary_selection request, "
"serial %"PRIu32" was never given to client", serial);
return;