Re: [PATCH v2] nvmem: core: Set no-read-write provider to avoid userspace read/write

[Gaurav Kohli <gkohli@xxxxxxxxxxxxxx>]

Hi Srinivas,

Thanks for the patch, Can you please merge , So will cherry pick the same.


Regards

Gaurav

On 3/25/2019 11:45 AM, Gaurav Kohli wrote:
> On 3/22/2019 11:42 PM, Gaurav Kohli wrote:
> > Hi Srinivas,
> >
> > Thanks for the patch, Something like this only i have tested in the 
> > morning, instead of unused, i have put dev group inside config as well.
> >
> > We will test the exact patch and update the same.
> >
> > Regards
> >
> > Gaurav
> >
> > On 3/22/2019 8:32 PM, Srinivas Kandagatla wrote:
> > > On 20/03/2019 17:50, Gaurav Kohli wrote:
> > > > > 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.
> > > Can you try below patch!
> Hi Srinivas,
>
> Thanks for the patch.
>
> I have checked the patch and also tested the same , and it is working 
> as expected(no creation of nvmem sysfs)
>
> Applied with some conflict on line 41.
>
> Reviewed-by: Gaurav Kohli <gkohli@xxxxxxxxxxxxxx>
> Tested-by: Gaurav Kohli <gkohli@xxxxxxxxxxxxxx>
>
> Regards
>
> Gaurav
>
>
> > > > > 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.
> > > DT way is totally NAK.
> > >
> > >
> > > --------------------------->cut<-----------------------------------
> > >
> > > From: Srinivas Kandagatla <srinivas.kandagatla@xxxxxxxxxx>
> > > Date: Wed, 20 Mar 2019 16:15:21 +0000
> > > Subject: [PATCH] nvmem: core: add support to NVMEM_NO_SYSFS_ENTRY
> > >
> > > Some users might not want to expose nvmem entry to sysfs and
> > > only intend to use kernel interface so add such provision.
> > >
> > > Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@xxxxxxxxxx>
> > > ---
> > >  Documentation/ABI/stable/sysfs-bus-nvmem |  2 ++
> > >  drivers/nvmem/Kconfig                    |  5 +++++
> > >  drivers/nvmem/core.c                     | 11 ++++++-----
> > >  3 files changed, 13 insertions(+), 5 deletions(-)
> > >
> > > diff --git a/Documentation/ABI/stable/sysfs-bus-nvmem 
> > > b/Documentation/ABI/stable/sysfs-bus-nvmem
> > > index 5923ab4620c5..12aab0a85fea 100644
> > > --- a/Documentation/ABI/stable/sysfs-bus-nvmem
> > > +++ b/Documentation/ABI/stable/sysfs-bus-nvmem
> > > @@ -6,6 +6,8 @@ Description:
> > >          This file allows user to read/write the raw NVMEM contents.
> > >          Permissions for write to this file depends on the nvmem
> > >          provider configuration.
> > > +        Note: This file is not present if CONFIG_NVMEM_NO_SYSFS_ENTRY
> > > +        is enabled
> > >
> > >          ex:
> > >          hexdump /sys/bus/nvmem/devices/qfprom0/nvmem
> > > diff --git a/drivers/nvmem/Kconfig b/drivers/nvmem/Kconfig
> > > index 0a7a470ee859..6ab3276d287c 100644
> > > --- a/drivers/nvmem/Kconfig
> > > +++ b/drivers/nvmem/Kconfig
> > > @@ -192,4 +192,9 @@ config SC27XX_EFUSE
> > >        This driver can also be built as a module. If so, the module
> > >        will be called nvmem-sc27xx-efuse.
> > >
> > > +config NVMEM_NO_SYSFS_ENTRY
> > > +    bool "No nvmem sysfs entry"
> > > +
> > > +    help
> > > +        Say Yes if you do not want to add nvmem entry to sysfs.
> > >  endif
> > > diff --git a/drivers/nvmem/core.c b/drivers/nvmem/core.c
> > > index b9a0270883a0..c70f183fe379 100644
> > > --- a/drivers/nvmem/core.c
> > > +++ b/drivers/nvmem/core.c
> > > @@ -216,7 +216,7 @@ static const struct attribute_group 
> > > nvmem_bin_rw_group = {
> > >      .attrs        = nvmem_attrs,
> > >  };
> > >
> > > -static const struct attribute_group *nvmem_rw_dev_groups[] = {
> > > +static const __maybe_unused struct attribute_group 
> > > *nvmem_rw_dev_groups[] = {
> > >      &nvmem_bin_rw_group,
> > >      NULL,
> > >  };
> > > @@ -240,7 +240,7 @@ static const struct attribute_group 
> > > nvmem_bin_ro_group = {
> > >      .attrs        = nvmem_attrs,
> > >  };
> > >
> > > -static const struct attribute_group *nvmem_ro_dev_groups[] = {
> > > +static const __maybe_unused struct attribute_group 
> > > *nvmem_ro_dev_groups[] = {
> > >      &nvmem_bin_ro_group,
> > >      NULL,
> > >  };
> > > @@ -265,7 +265,7 @@ static const struct attribute_group 
> > > nvmem_bin_rw_root_group = {
> > >      .attrs        = nvmem_attrs,
> > >  };
> > >
> > > -static const struct attribute_group *nvmem_rw_root_dev_groups[] = {
> > > +static const __maybe_unused struct attribute_group 
> > > *nvmem_rw_root_dev_groups[] = {
> > >      &nvmem_bin_rw_root_group,
> > >      NULL,
> > >  };
> > > @@ -289,7 +289,7 @@ static const struct attribute_group 
> > > nvmem_bin_ro_root_group = {
> > >      .attrs        = nvmem_attrs,
> > >  };
> > >
> > > -static const struct attribute_group *nvmem_ro_root_dev_groups[] = {
> > > +static const __maybe_unused struct attribute_group 
> > > *nvmem_ro_root_dev_groups[] = {
> > >      &nvmem_bin_ro_root_group,
> > >      NULL,
> > >  };
> > > @@ -688,6 +688,7 @@ struct nvmem_device *nvmem_register(const struct 
> > > nvmem_config *config)
> > >      nvmem->read_only = device_property_present(config->dev, 
> > > "read-only") |
> > >                 config->read_only;
> > >
> > > +#if !defined(CONFIG_NVMEM_NO_SYSFS_ENTRY)
> > >      if (config->root_only)
> > >          nvmem->dev.groups = nvmem->read_only ?
> > >              nvmem_ro_root_dev_groups :
> > > @@ -696,7 +697,7 @@ struct nvmem_device *nvmem_register(const struct 
> > > nvmem_config *config)
> > >          nvmem->dev.groups = nvmem->read_only ?
> > >              nvmem_ro_dev_groups :
> > >              nvmem_rw_dev_groups;
> > > -
> > > +#endif
> > >      device_initialize(&nvmem->dev);
> > >
> > >      dev_dbg(&nvmem->dev, "Registering nvmem device %s\n", 
> > > config->name);
--
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