On Tue, Nov 15, 2022 at 12:40:57PM -0600, Allen Webb wrote:

When i get the modinfo for usbhid, there are no aliases listed:

localhost ~ # modinfo usbhid
name:           usbhid
filename:       (builtin)
author:         Andreas Gal
author:         Vojtech Pavlik
author:         Jiri Kosina
description:    USB HID core driver
file:           drivers/hid/usbhid/usbhid
license:        GPL
parm:           quirks:Add/modify USB HID quirks by specifying
quirks=vendorID:productID:quirks where vendorID, productID, and quirks
are all in 0x-prefixed hex (array of charp)
parm:           ignoreled:Autosuspend with active leds (uint)
parm:           kbpoll:Polling interval of keyboards (uint)
parm:           jspoll:Polling interval of joysticks (uint)
parm:           mousepoll:Polling interval of mice (uint)

Hm. Interesting. Actually, alias gets into modules.builtin.modinfo:

$ tr '\0' '\n' <  /lib/modules/`uname -r`/modules.builtin.modinfo |grep ^crc32c_generic.alias=
crc32c_generic.alias=crypto-crc32c-generic
crc32c_generic.alias=crc32c-generic
crc32c_generic.alias=crypto-crc32c
crc32c_generic.alias=crc32c

bluetooth however has an alias listed:

localhost ~ # modinfo bluetooth
filename:
/lib/modules/5.10.154-20424-gea7532c123d8/kernel/net/bluetooth/bluetooth.ko.gz
author:         Marcel Holtmann <marcel@holtmann.org>
description:    Bluetooth Core ver 2.22
version:        2.22
license:        GPL
alias:          net-pf-31
vermagic:       5.10.154-20424-gea7532c123d8 SMP preempt mod_unload
name:           bluetooth
intree:         Y
retpoline:      Y
depends:        ecdh_generic
srcversion:     F8E46CD048C50B0AA1CD471
parm:           disable_esco:Disable eSCO connection creation (bool)
parm:           enable_ecred:Enable enhanced credit flow control mode (bool)
parm:           disable_ertm:Disable enhanced retransmission mode (bool)

I believe the reason for this is many modules use `#define
MODULE_DEVICE_TABLE(type, name)` which is a noop for buildin modules.
I have a local patch that resolves that issue here:
See: https://chromium-review.googlesource.com/c/chromiumos/third_party/kernel/+/3840672/1/include/linux/module.h#b246

However, I probably ought to rework that patch to create the
MODULE_ALIAS defines instead of the buildin.alias file.

On Tue, Nov 15, 2022 at 11:35 AM Luis Chamberlain [off-list ref] wrote:

quoted

On Tue, Nov 15, 2022 at 10:05:35AM -0600, Allen Webb wrote:

quoted

On Mon, Nov 14, 2022 at 11:22 AM Lucas De Marchi
[off-list ref] wrote:

quoted

On Mon, Nov 14, 2022 at 10:42:50AM -0600, Allen Webb wrote:

quoted

On Fri, Nov 11, 2022 at 12:29 PM Luis Chamberlain [off-list ref] wrote:

quoted

On Fri, Nov 11, 2022 at 09:28:52AM -0600, Allen Webb wrote:

quoted

USB devices support the authorized attribute which can be used by
user-space to implement trust-based systems for enabling USB devices. It
would be helpful when building these systems to be able to know in
advance which kernel drivers (or modules) are reachable from a
particular USB device.

This information is readily available for external modules in
modules.alias. However, builtin kernel modules are not covered. This
patch adds a sys-fs attribute to both builtin and loaded modules
exposing the matching rules in the modalias format for integration
with tools like USBGuard.

Signed-off-by: Allen Webb <redacted>

Thanks for the patch Allen!

I'd rather have something generic though, and it would seem kmod [0] already
does this, have you seen the kmod support for builtin.alias.bin

Can't that be used?

Probably, but I don't see the builtin.alias.bin in my build. Is it experimental?

no. That is generated by depmod since v27 using modules.builtin.modinfo
generated by the kernel build system. Highly recommend v30 though
as there were fixes in v28 and v29 and some changes to speed up its
generation/use in v30:  See entries mentioning
builtin.alias and bultin.modinfo in
https://git.kernel.org/pub/scm/utils/kernel/kmod/kmod.git/tree/NEWS

libkmod/modprobe/modinfo also have the corresponding changes to lookup that
index when resolving aliases.

I see the file but it is largely missing the aliases I am interested
in, so it looks like I might need to modify my patch that creates
buildin.alias to add the missing alias defines in the header along
with the other module metadata for builtin modules. Does this sound
right to you?

Can you clarify what is missing and why? And an RFC is welcomed if it
helps demonstrates what you mean.

  Luis

-- 
Rgrds, legion