On Wed 2018-04-11 17:27:16, David Howells wrote:

Disallow opening of debugfs files that might be used to muck around when
the kernel is locked down as various drivers give raw access to hardware
through debugfs.  Given the effort of auditing all 2000 or so files and
manually fixing each one as necessary, I've chosen to apply a heuristic
instead.  The following changes are made:

 (1) chmod and chown are disallowed on debugfs objects (though the root dir
     can be modified by mount and remount, but I'm not worried about that).

This has nothing to do with the lockdown goals, right? I find chown of
such files quite nice, to allow debugging without doing sudo all the time.

 (2) When the kernel is locked down, only files with the following criteria
     are permitted to be opened:

	- The file must have mode 00444
	- The file must not have ioctl methods
	- The file must not have mmap

Dunno. Would not it be nicer to go through the debugfs files and split
them into safe/unsafe varieties?

									Pavel
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