Messages in this thread | | | From | Arnd Bergmann <> | Date | Tue, 4 Aug 2020 22:46:34 +0200 | Subject | Re: [PATCH] mtd: spi-nor: intel-spi: Do not try to make the SPI flash chip writable |
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On Tue, Aug 4, 2020 at 9:57 PM Daniel Gutson <daniel@eclypsium.com> wrote: > On Tue, Aug 4, 2020 at 4:06 PM Arnd Bergmann <arnd@arndb.de> wrote: > > On Tue, Aug 4, 2020 at 5:49 PM Daniel Gutson <daniel@eclypsium.com> wrote: > > > On Tue, Aug 4, 2020 at 12:21 PM Arnd Bergmann <arnd@arndb.de> wrote: > > >> On Tue, Aug 4, 2020 at 3:58 PM Daniel Gutson > > >> <daniel.gutson@eclypsium.com> wrote: > > > > > > What about just saying > > > > > > "This patch removes the attempt by the intel-spi-pci driver to > > > make the chip always writable." > > > > Yes, that is much better, though it still sounds like it would at the > > moment allow writing to the device from software without also > > setting the module parameter. I would say something like > > > > "Disallow overriding the write protection in the PCI driver > > with a module parameter and instead honor the current > > state of the write protection as set by the firmware." > > But wait, Mika, the author of the file, asked earlier not to remove > the module parameter of intel-spi, and just remove the unconditional > attempt to turn the chip writable in intle-spi-pci.
Yes, and I think that is fine (aside from the inconsistency with bay trail that you have not commented on), but that only touches the hardware write-protection, which doesn't really have any effect unless user space also configures the driver module to allow writing to the mtd device.
> So I'm not touching intel-pci, just removing that code from > intel-spi-pci without adding a new module parameter. > > Are you aligned on this?
One of us is still very confused about what the driver does. You seem to have gone back to saying that without the change a user could just write to the device even without passing the module parameter to intel-spi.ko?
Maybe you should start by explaining what scenario you actually want to prevent here. Is it
a) the hardware write-protect bit getting changed, which introduces the possibility of corrupting the flash even if nothing tries to write to it,
b) root users setting the device writable with the intention of writing to it even though firmware has politely asked for this not to be done (by setting the write-protect bit but not preventing it from being disabled again), or
c) a writeable mtd device showing up even without the module parameter being set at all?
I thought the initial patch was about c) which turned out to be a non-issue, and then the later patch being about b).
Arnd
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