loader: Add firmware info version check to downgrade prevention

[sigvartmh]

For nRF53, the only existing version number metadata is stored in the firmware_info structure in the network core. This utilizes PCD to read out the version number and compares it against the version number found in the secondary slot for the network core.

Ref. NCSDK-21379

[sigvartmh]

Not finalized I'm pulling things out into a single function something like boot_cmp_net to hide behind a #define flag .

I understand that this is not the best solution but it's what I've come up with as a stop gap to get something in before RC1.

See https://github.com/nrfconnect/sdk-nrf/pull/12409/files

For the function refactoring into boot_hooks_nrf53.

[sigvartmh]

@nordicjm So I've fetched out the idea a bit more, but I'm not 100% happy with the end result. ideally, I would have boot_cmp as a hook with a Regular and unique case.

The problem is that boot_cmp does not take in any state or slot, so you don't know which slot you are doing the comparison against.

Anyways please review the idea if possible, some one is waiting for this to go in for RC1

[sigvartmh]

To answer both @de-nordic and @nordicjm, the idea here is to do something like this:

int boot_read_image_header_hook(int img_index, int slot, struct image_header *img_head)
So inside, you would either do regular compare or do the boot_cmp_net when if image == 1 I'll refactor this to reflect this better.

[sigvartmh]

@de-nordic @nordicjm So I've reworked it a bit but I'm uncertain if I should push even more of the logic over into the nrf53_hook file.

[nordicjm]

There is probably a PCD hook file somewhere that would need a check adding too

[sigvartmh]

So currently the placement of the function is a bit weird and I think I should change the naming back to boot_ instead of pcd. Tried to move all of it into PCD but it had some dependencies to MCUBoot so it was easier just to leave it in nrf53_hooks.c added #ifdefs there. I wonder if you prefer the naming boot_version_cmp_net ?

[de-nordic]

Question: wouldn't it be more useful if the function would rather extract version out of PCD and comparison would happen on the MCUboot side?

[sigvartmh]

Doesn't use the same versioning scheme. Netcore uses FW_INFO which is just a single value while MCUBoot does the major.minor.rev semantic versioning.

The end goal is to consolidate them but for now, this is what we can provide.

The command is running on the MCUBoot side but it fetches the current version number through PCD from the network core and does the comparison on Application(MCUBoot side).

[sigvartmh]

So do you belive we can get this in for 2.5.0 @nordicjm @de-nordic ?

[de-nordic]

So do you belive we can get this in for 2.5.0 @nordicjm @de-nordic ?

Yes, but post rc1.

We have to actually, as this is bugfix.