KPasswordEdit and security

[Thiago Macieira]

Albert Astals Cid wrote:
>> I *think* it is because you can set the password data to be in a
>> locked memory page (so it won't be swapped out and written on the
>> disk) when using a char *, but you can't do that with a QString,
>> because QString controls the buffer, and there's no way for you to
>> tell it it should use "safe" memory. I haven't looked at the code,
>> though, so I don't know if this is happenning or not. IMO, having a
>> password be swapped out to the disk would be an unacceptable security
>> breach.
>
>I had a look to the code and did not found any call that seems to do
> that, do you know how does one do that? (locking the memory page).

It requires an mlockall(2) call, which is only possible in privileged 
programs. So we'd need all programs that use KPasswordEdit to be setuid 
root -- which our libraries don't allow.

So there's no page-locking security.

-- 
  Thiago Macieira  -  thiago (AT) macieira.info - thiago (AT) kde.org
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