On Sat, Nov 19, 2022 at 01:20:09AM -0500, Nayna wrote:

On 11/17/22 16:27, Greg Kroah-Hartman wrote:

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On Mon, Nov 14, 2022 at 06:03:43PM -0500, Nayna wrote:

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On 11/10/22 04:58, Greg Kroah-Hartman wrote:

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On Wed, Nov 09, 2022 at 03:10:37PM -0500, Nayna wrote:

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On 11/9/22 08:46, Greg Kroah-Hartman wrote:

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On Sun, Nov 06, 2022 at 04:07:42PM -0500, Nayna Jain wrote:

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securityfs is meant for Linux security subsystems to expose policies/logs
or any other information. However, there are various firmware security
features which expose their variables for user management via the kernel.
There is currently no single place to expose these variables. Different
platforms use sysfs/platform specific filesystem(efivarfs)/securityfs
interface as they find it appropriate. Thus, there is a gap in kernel
interfaces to expose variables for security features.

Define a firmware security filesystem (fwsecurityfs) to be used by
security features enabled by the firmware. These variables are platform
specific. This filesystem provides platforms a way to implement their
    own underlying semantics by defining own inode and file operations.

Similar to securityfs, the firmware security filesystem is recommended
to be exposed on a well known mount point /sys/firmware/security.
Platforms can define their own directory or file structure under this path.

Example:

# mount -t fwsecurityfs fwsecurityfs /sys/firmware/security

Why not juset use securityfs in /sys/security/firmware/ instead?  Then
you don't have to create a new filesystem and convince userspace to
mount it in a specific location?

  From man 5 sysfs page:

/sys/firmware: This subdirectory contains interfaces for viewing and
manipulating firmware-specific objects and attributes.

/sys/kernel: This subdirectory contains various files and subdirectories
that provide information about the running kernel.

The security variables which are being exposed via fwsecurityfs are managed
by firmware, stored in firmware managed space and also often consumed by
firmware for enabling various security features.

Ok, then just use the normal sysfs interface for /sys/firmware, why do
you need a whole new filesystem type?

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  From git commit b67dbf9d4c1987c370fd18fdc4cf9d8aaea604c2, the purpose of
securityfs(/sys/kernel/security) is to provide a common place for all kernel
LSMs. The idea of
fwsecurityfs(/sys/firmware/security) is to similarly provide a common place
for all firmware security objects.

/sys/firmware already exists. The patch now defines a new /security
directory in it for firmware security features. Using /sys/kernel/security
would mean scattering firmware objects in multiple places and confusing the
purpose of /sys/kernel and /sys/firmware.

sysfs is confusing already, no problem with making it more confusing :)

Just document where you add things and all should be fine.

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Even though fwsecurityfs code is based on securityfs, since the two
filesystems expose different types of objects and have different
requirements, there are distinctions:

1. fwsecurityfs lets users create files in userspace, securityfs only allows
kernel subsystems to create files.

Wait, why would a user ever create a file in this filesystem?  If you
need that, why not use configfs?  That's what that is for, right?

The purpose of fwsecurityfs is not to expose configuration items but rather
security objects used for firmware security features. I think these are more
comparable to EFI variables, which are exposed via an EFI-specific
filesystem, efivarfs, rather than configfs.

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2. firmware and kernel objects may have different requirements. For example,
consideration of namespacing. As per my understanding, namespacing is
applied to kernel resources and not firmware resources. That's why it makes
sense to add support for namespacing in securityfs, but we concluded that
fwsecurityfs currently doesn't need it. Another but similar example of it
is: TPM space, which is exposed from hardware. For containers, the TPM would
be made as virtual/software TPM. Similarly for firmware space for
containers, it would have to be something virtualized/software version of
it.

I do not understand, sorry.  What does namespaces have to do with this?
sysfs can already handle namespaces just fine, why not use that?

Firmware objects are not namespaced. I mentioned it here as an example of
the difference between firmware and kernel objects. It is also in response
to the feedback from James Bottomley in RFC v2 [https://lore.kernel.org/linuxppc-dev/41ca51e8db9907d9060cc38adb59a66dcae4c59b.camel@HansenPartnership.com/ (local)].

I do not understand, sorry.  Do you want to use a namespace for these or
not?  The code does not seem to be using namespaces.  You can use sysfs
with, or without, a namespace so I don't understand the issue here.

With your code, there is no namespace.

You are correct. There's no namespace for these.

So again, I do not understand.  Do you want to use filesystem
namespaces, or do you not?

How again can you not use sysfs or securityfs due to namespaces?  What
is missing?

confused,

greg k-h