Messages in this thread | | | Subject | Re: [PATCH v2] nvmem: core: Set no-read-write provider to avoid userspace read/write | From | Gaurav Kohli <> | Date | Wed, 20 Mar 2019 23:20:59 +0530 |
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On 3/20/2019 9:56 PM, Srinivas Kandagatla wrote: > > > On 20/03/2019 15:50, Gaurav Kohli wrote: >> >> On 3/20/2019 8:04 PM, Srinivas Kandagatla wrote: >>> >>> >>> On 17/03/2019 14:12, Gaurav Kohli wrote: >>>> Current nvmem framework allows user space to read all register space >>>> populated by nvmem binary file, In case we don't want to expose value >>>> of registers to userspace and only want kernel space to read cell >>>> value from nvmem_cell_read_u32. >>>> >>>> To protect the same, Add no-read-write property to prevent read >>>> from userspace. >>>> >>> >>> Can you explain the real need of this? >>> Is there any issue you are noticing while reading nvmem content from >>> userspace? >>> >> Hi Srinivas, >> >> >> No, We are not observing any issue, nvmem is dumping the data properly. >> >> But there are certain register, which we don't want to expose to user >> space and want kernel space can only read via nvmem_cell_read. > Am guessing these are some kind of keys or something that you do not > want user to see. > Hi Srinivas,
Thanks.
Yes exactly, there are certain keys or even certain bit that we don't want to expose to user.
> Is root only option not helping you in this case? Yes we want to protect at root level as well, i mean it is better if we can avoid exposing to userspace at all. > > We could go down the route of adding new config option something like > CONFIG_NVMEM_NO_SYSFS_ENTRY to prevent adding nvmem entry in userspace. > > Let me know if you are happy to create a patch for this change?
I am happy with either way config option or dt binding(seems easy), please let me know we will post new patch for the same.
In config option, do i have to remove all binary creation code of nvmem , correct? or simply put a check like dt binding option
so user cannot read it.
Thanks
Gaurav
> > Thanks, > srini > >> >> In existing design, even if we read cell from kernel space, nvmem >> binary files is still populated to user space unconditionally. >> >> Regards >> >> Gaurav
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