Messages in this thread | | | From | Robin Getz <> | Subject | Re: debugfs & vfs file permission issue? | Date | Tue, 6 Jan 2009 16:20:54 -0500 |
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On Tue 6 Jan 2009 10:20, Mike Frysinger pondered: > On Tue, Jan 6, 2009 at 10:12, Robin Getz wrote: > > On Tue 6 Jan 2009 07:05, Robin Getz suggested: > >> adding a readonly, and writeonly, and ensuring that when you call > >> debugfs_create_*, the mode is checked, and the "correct" fops are set > >> doesn't seem like it would be a bad idea? This would enforce the > >> kernel programmer's view on the world, and not allow pesky root users > >> to override things.... > >> > >> Greg - would you take something like that? > > > > How about this? > > > > Feel free to nak it - we can do the same thing where we are calling the > > debugfs_create_* functions - this just makes it cleaner in my opinion. > > > > --- > > > > In many SOC implementations there are hardware registers can be read only, > > or write only. This extends the debugfs to enforce the file permissions for > > these types of registers, by providing a set of fops which are read only > > or write only. This assumes that the kernel developer knows more about the > > hardware than the user (even root users) - which is normally true. > > we want it for cpu registers, but i dont see any reason why this > wouldnt also apply to external devices attached via memory interfaces > ... fifos and such ...
Yes - Although the existing use case is for SOC on chip registers - it applies to anything where the kernel developer really doesn't want to allow the user to do an access that will cause a negative side effect (crash, effect fifos, etc).
-Robin
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