Design proposal to Non-Interactive password update for REST client

[vishwa]

Tom and I talked and we should be fine with my current proposal.

Here is what we talked:

There would be a new encryption algorithm which would be denoted by some 
number ( Like 1 is for MD5 ) and crypt(3) would be enhanced to handle 
that. Since my proposal does not interpret the number and uses AS IS to 
generate the hash, we should be fine.

On 08/28/2017 05:04 PM, vishwa wrote:
> On 08/14/2017 10:05 PM, Patrick Williams wrote:
>> On Fri, Aug 11, 2017 at 09:48:48PM +0530, vishwa wrote:
>>> This email is about openbmc/openbmc#1714 ( REST API to update root
>>> password )
>>>
>>> Goal is to do Non-interactive password updates to enable a REST client
>>> to update the root password.
>>>
>>> My proposal is to use `getspent(3)` and `putspent(3)` and here is 
>>> the flow.
>>>
>>> REST client will provide a method that takes std::string as parameter.
>>>
>>> The Provider at the BMC will receive the password and does these:
>>>
>>>    - Executes `getspent(3)` for "root" and gets the entries.
>> Make sure you're using getspent_r for this.
> Sure
>>
>> Should be done based on any user, not just 'root'.  We might only
>> support 'root' now but will want to easily add support for other users
>> in the near future.
>
> Okay. I will have [User] and [Password] in the yaml.
>>>    - Parses the `sp_pwdp` and extracts `encryption method` , `salt`.
>> Is there a portable way to do this?  Is there any library that exists
>> already?
> I tried to look for that and did not find. I will continue looking.
>> Tom and I spoke previously about a possible non-standard crypt algorithm
>> in order to satisfy some of the requirements of IPMI RMCP+'s
>> authentication protocol without storing plaintext passwords. Please
>> follow up with him and see if what you are proposing here will mesh with
>> what he was planning.
>
> I told Tom about this and he would get back to me.
>
> BTW, I put the proposal of using crypt() after looking at:
>
> https://github.com/shadow-maint/shadow/blob/master/src/passwd.c#L245
>
> and
>
> https://github.com/shadow-maint/shadow/blob/6fbc11ce2178205968c37853db752729359c9893/lib/encrypt.c 
>
>
>>>    - Makes a call to `crypt(3)` with the extracted `salt` and `user
>>> input` and generates encrypted pass-code
>> The salt can/should be random for each password, shouldn't it? It
>> sounds like you are attempting to reuse the salt from the previous
>> password and that is not required nor preferred to the best of my
>> knowledge.
>>
> Okay. I can generate a random string from [a-zA-Z0-9./] as needed by 
> crypt()
>>>    - Populates the structure and calls `putspent(3)` to update the 
>>> password
>>>
>>> Please let me know your opinion on this.
>>>
>>> Thank you,
>>>
>>> !! Vishwa !!
>>>
>