BackDoorLock hack - prevents silent updates

[knc1]

Originally Posted by Dexmaster

I've checked that one, that's the same zip, even file dates are same...

I guess that I was wrong then, the Backdoor Lock was "fixed" as long ago as those dates show.

It seems strange to me, just from the numbering, that your device went from firmware 5.6.1.anything to 5.6.2.something.
See: https://www.mobileread.com/forums/sho...d.php?t=262279

But it looks like that is what they did (went from 5.6.1.0.6 to 5.6.2.1).
See: http://www.amazon.com/gp/help/custom...deId=200203720
Unless that 2nd gen PW list is in error (which has also happened in the past).

[Dexmaster]

Originally Posted by knc1

It seems strange to me, just from the numbering, that your device went from firmware 5.6.1.anything to 5.6.2.something.
See: https://www.mobileread.com/forums/sho...d.php?t=262279

I have Airplane mode always on, so I have checked and I had a Kindle PW2 with a FW "5.6.1". Then I switched Airplane mode off, and after a day of it I've got FW "5.6.2.1", I still had JB but I needed to reinstall all hacks I used.

Originally Posted by knc1

Unless that 2nd gen PW list is in error (which has also happened in the past).

I'm not sure I understood correctly, If needs be I can replicate the same thing by rolling back a firmware image over my device. Then update it to 5.6.1 and check one more time, but I'm sure this error would persist.

I've given you a log and there is nothing about UNLOCKING A BACK DOOR, so I'm sure it's unpredicted behavior of BackDoorLock hack and another silent update to 5.6.x FW.

So I'll try to be very careful, I think as an alternative I'll leave only 50 Mb of space when switchin the Aiplane Mode off. I think I'll even create script for it, my idea was to create a large dummy file and update it's filesize manually by KUAL or PC.

[knc1]

Originally Posted by Dexmaster

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So I'll try to be very careful, I think as an alternative I'll leave only 50 Mb of space when switchin the Aiplane Mode off. I think I'll even create script for it, my idea was to create a large dummy file and update it's filesize manually by KUAL or PC.

That second link (the one you cut out from your quote) shows that Amazon did indeed go from a 5.6.1 to a 5.6.2.

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I can't recall how FAT32 handles 'sparse' files, but try that first, just write the last (erase block size) block.
I.E:
dd if=/dev/zero bs=4096 seek=250K count=1 of=space_waste.txt

If FAT32 can do that without writing the 250K blocks that where skipped on output, it will be both faster and less wear on the flash (only one write command).

[Dexmaster]

FAT32 does not support "sparse" attribute... ( info: http://mldonkey.sourceforge.net/Sparse_files ) So I would have to find out some other solution...

I have another idea of non-deletable FAT32 file (update.bin.tmp.partial) http://superuser.com/questions/42421...n-an-usb-drive , but I'm not sure it will help with Linux on Kindle and it's way to silently download OTA updates... What do you think? Do you have a fast way to test it out?

*(if not I can test it out myself later this week, I would need to lower my FW, I haven't done it but I've seen it and it doesn't look too hard)

[knc1]

Originally Posted by Dexmaster

- - - - -
I have another idea of non-deletable FAT32 file (update.bin.tmp.partial) http://superuser.com/questions/42421...n-an-usb-drive , but I'm not sure it will help with Linux on Kindle and it's way to silently download OTA updates... What do you think? Do you have a fast way to test it out?
- - - - -

Nice find.
I suppose we could think of that as the Windows version of "Immutable" - at least for our purposes.

I don't have a ready-to-run solution for setting those bits in the FAT32 directory -
But it should not be too hard to make one (maybe runnable via a KUAL menu entry).

If you have access to a Linux PC, then you can easily get a copy of the FAT32 backing store - including MBR, Partition table, Directory, and data area.
See: https://www.mobileread.com/forums/sho...d.php?t=262358 (and maybe the older write-up).

And under Linux, that file copy of the backing store device can be used just as if it was a real device (that is what losetup does, a file -> device translation).

Handy for testing out utilities for diddling the FAT32 directory entries.

It will not matter to the final solution if the user only has Windows on their PC - we have Linux on the Kindle, which is where the bit diddle utility will eventual run.

And that may be where we have trouble - the Linux FAT32 driver may not respond the same way to those hidden bits that the Windows driver/system does.
But certainly worth spending some time trying it out.

If your going to downgrade and then let the device attempt to download the OTA update (hopefully aborting its download before it completes) -
One of the things to check for, is the '.tmp' sub-string part of the temporary filename.

It has been reported that perhaps 5.6.x does not include that in the temporary filename.

And that might be why the current Backdoor Lock fails (its expecting the wrong temporary filename).

- - - -

Note: to only diddle the directory entries - you only need the first 8196 bytes (two flash erase blocks, 16 logical sectors) of the backing store.
That will get you the FAT32 MBR, Partition table, and Directory (without the 2g data area).

[Dexmaster]

I've created update.bin.tmp.partial file on my Kindle, then with a help of Active@ Disk Editor (on my pc) I've changed file attributes to 42 and I couldn't remove it on my PC, but I removed it through KTerm rm command quite easily. So I'll downgrade/upgrade and test this method later but I don't have too high hopes.

Also I'll note all files and changes, maybe there is a better solution somewhere out there ) I haven't looked on BackDoorLock itself maybe I'll understand it and get what chaged or what has an issue )

P.S. Funny thing it's the 42 )

[knc1]

Create two directories:

Kindle:/update.bin.tmp.partial
and
Kindle:/update.bin.partial

Then set the y bit (and maybe hidden and/or system) on those.

[NiLuJe]

Yup, vfat doesn't care about reserved bits, won't help on Linux .

[eschwartz]

The jailbreak already mounts the userstore as "exec", yes? Just set it as "sys_immutable" as well. Then the backDoorLock can mark a directory with ATTR_SYS. (Is there any common utility that can set these vfat flags? )


Of course, Amazon is just going to read this thread and "fix" that too.

[NiLuJe]

Except that /mnt/us is a weird fuse proxy, which doesn't give a crap about FAT32 attributes ;/. I'm not even sure vfat doesn't already handle those in a very lenient fashion anyway...

I can't remember right now if I actually went to the trouble of double-checking on device with fatattr, but I *think* I did.

[GoSharks]

I'm a little confused by the last series of posts.... they would suggest that the BackDoorLock does not currently stop OTA updates on the PW2 FW> 5.6.* (and possibly the PW 1?). Is this correct or did I misinterpret things?
Thanks!

[juan_carlos]

Originally Posted by GoSharks

I'm a little confused by the last series of posts.... they would suggest that the BackDoorLock does not currently stop OTA updates on the PW2 FW> 5.6.* (and possibly the PW 1?). Is this correct or did I misinterpret things?
Thanks!

It didn't work for me on PW2, and others had similar experiences too.

[knc1]

Originally Posted by juan_carlos

It didn't work for me on PW2, and others had similar experiences too.

Your PW-2 was updated from <what version> to <what other version> ?

[juan_carlos]

Originally Posted by knc1

Your PW-2 was updated from <what version> to <what other version> ?

From 5.6.1.0.6 to 5.6.2.1 with bdl12 in locked state. But I already reported this in #154 and #159.

[knc1]

Originally Posted by juan_carlos

From 5.6.1.0.6 to 5.6.2.1 with bdl12 in locked state. But I already reported this in #154 and #159.

I read a lot of reports.
Nothing personal intended that I didn't recall the specifics of yours.

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Could you check if your 5.6.2.1 can be downgraded for us?
The PW-1 installation of 5.6.1.1 can be downgraded, see:
https://www.mobileread.com/forums/sho...d.php?t=263411

If you can, then I will ask you to let it start downloading the 5.6.2.1 OTA update (again), but to take the Kindle off-line before the download completes so we can learn what filenames are being used.