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dix: helper for checking whether window ID belongs to a root window 

This helper checks whether a given XID belongs to some screen's
root window. It does so by looking up the window and comparing that
with the window's screen's root window pointer. The resource lookup
is intentionally being on behalf of the serverClient, so the fired
XACE hook doesn't treat it as an actual client's request.

It's explicitly designed for being used by callback handlers.

Signed-off-by: Enrico Weigelt, metux IT consult <info@metux.net>
This commit is contained in:
Enrico Weigelt, metux IT consult 2025-03-21 17:19:34 +01:00
parent 950cfb2bdc
commit 473b8a0e38
2 changed files with 31 additions and 0 deletions
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19
dix/window.c
View File

@ -3715,3 +3715,22 @@ WindowGetVisual(WindowPtr pWin)
return &pScreen->visuals[i];
return 0;
}
/*
* @brief check whether a window (ID) is a screen root window
*
* The underlying resource query is explicitly done on behalf of serverClient,
* so XACE resource hooks don't recognize this as a client action.
* It's explicitly designed for use in hooks that don't wanna cause unncessary
* traffic in other XACE resource hooks: things done by the serverClient usually
* considered safe enough for not needing any additional security checks.
* (we don't have any way for completely skipping the XACE hook yet)
*/
Bool dixWindowIsRoot(Window window)
{
WindowPtr pWin;
int rc = dixLookupWindow(&pWin, window, serverClient, DixGetAttrAccess);
if (rc != Success)
return FALSE;
return (pWin == pWin->drawable.pScreen->root);
}

12
dix/window_priv.h
View File

@ -41,4 +41,16 @@ WindowPtr dixCreateWindow(Window wid,
*/
Bool MakeWindowOptional(WindowPtr pWin);
/*
* @brief check whether a window (ID) is a screen root window
*
* The underlying resource query is explicitly done on behalf of serverClient,
* so XACE resource hooks don't recognize this as a client action.
* It's explicitly designed for use in hooks that don't wanna cause unncessary
* traffic in other XACE resource hooks: things done by the serverClient usually
* considered safe enough for not needing any additional security checks.
* (we don't have any way for completely skipping the XACE hook yet)
*/
Bool dixWindowIsRoot(Window window);
#endif /* _XSERVER_DIX_WINDOW_PRIV_H */