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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