[Buildroot] Root password and ssh issues

[Titouan Christophe]

Hello Michael, Thomas, Peter and all,

I'm also running my test device with Buildroot 2020.02.4, dropbear and 
root:root password authentication; I cannot reproduce the problem.

On 7/08/20 13:12, Peter Seiderer wrote:
> Hello Michael,
> 
> On Fri, 7 Aug 2020 12:21:51 +0200, Michael Opdenacker <michael.opdenacker at bootlin.com> wrote:
> 
>> Hi Thomas,
>>
>> Thanks for your quick reply!
>>
>>
>>> What is the state of /etc/shadow with the non-working SSH login, and
>>> then the state of /etc/shadow after resetting the password with passwd
>>> ? I think I remember some issues with the expiration date/time of the
>>> password, or something like that.
>>
>>
>> Here are the details
>>
>> # ls -la /etc/shadow
>> -rw-------    1 1000     1000           190 Aug  7  2020 /etc/shadow
>>
>> # cat /etc/shadow
>> root:$5$D1pz/P1l$JCZhyjzCCqmXbnPx7g/mBtNtSSKkMqgctsmV/zBmlR2:::::::

[--SNIP--]

>> # cat /etc/shadow
>> root:$1$SYGd3a37$u2RV/VOsLPqWznY4GR1jU.:13514::::::

So, when you used `passwd`, the password hashing algorithm has changed 
from SHA512 ($5$) to MD5 ($1$). I found a similar issue though it dates 
back to 2016, maybe that could help: 
http://lists.busybox.net/pipermail/buildroot/2016-February/154348.html

>> daemon:*:::::::
>> bin:*:::::::
>> sys:*:::::::
>> sync:*:::::::
>> mail:*:::::::
>> www-data:*:::::::
>> operator:*:::::::
>> nobody:*:::::::
>>
>> # ls -la /etc/shadow
>> -rw-------    1 1000     1000           174 Aug  7  2020 /etc/shadow
>>
>> I set the password the "root" (both in "menuconfig" and then through the
>> "passwd" command). Only after this command can I login through ssh.
>>
> 
> No problem here to login via ssh via preset password (raspberrypi4_64_defconfig with
> additional dropbear enabled):
> 
> BR2_PACKAGE_DROPBEAR=y
> BR2_PACKAGE_DROPBEAR_CLIENT=y
> BR2_PACKAGE_DROPBEAR_DISABLE_REVERSEDNS=y
> BR2_PACKAGE_DROPBEAR_SMALL=y
> # BR2_PACKAGE_DROPBEAR_WTMP is not set
> # BR2_PACKAGE_DROPBEAR_LASTLOG is not set
> # BR2_PACKAGE_DROPBEAR_LEGACY_CRYPTO is not set
> BR2_PACKAGE_DROPBEAR_LOCALOPTIONS_FILE=""
> 
> What looks strange are your /etc/shadow permissions, should give
> root/root for user/group...
> 
> What is the /var/log/messages dropbear output for failure/success?
> 
> What is your config/defconfig?
> 
> Regards,
> Peter
> 
>> Cheers,
>>
>> Michael.
>> 

Best regards,
Titouan