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Date:      Fri, 23 Feb 2018 10:16:28 -0700
From:      Warner Losh <imp@bsdimp.com>
To:        Ben RUBSON <ben.rubson@gmail.com>
Cc:        Freebsd fs <freebsd-fs@freebsd.org>, FreeBSD-scsi <freebsd-scsi@freebsd.org>
Subject:   Re: smartmontools and kern.securelevel
Message-ID:  <CANCZdfqiK2Hz20Sso0_uA8FAD4=2z0FY=iPLdK=dX5p5OPq_3Q@mail.gmail.com>
In-Reply-To: <4C1D44AF-8247-4601-A39C-A8C0A5C8CBD8@gmail.com>
References:  <0985ABD3-D141-4EE2-B1B3-3016B16E2B68@gmail.com> <CANCZdfo4PZv7ueCZUZ_bnPu26mL12HAUzfoszhXeDkrTShV6zA@mail.gmail.com> <4C1D44AF-8247-4601-A39C-A8C0A5C8CBD8@gmail.com>

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On Fri, Feb 23, 2018 at 9:46 AM, Ben RUBSON <ben.rubson@gmail.com> wrote:

> On 23 Feb 2018, Warner Losh wrote:
>
> On Fri, Feb 23, 2018 at 8:20 AM, Ben RUBSON <ben.rubson@gmail.com> wrote:
>>
>> Hi,
>>>
>>> I run smartmontools on my storage servers, to launch periodic disk tests
>>> and alert on disk errors.
>>>
>>> Unfortunately, if we set sysctl kern.securelevel >=2, smartmontools does
>>> not work anymore.
>>> Certainly because it needs to write directly to raw devices.
>>> (details of the levels, -1 to 3, in security(7))
>>>
>>> Any workaround to this ?
>>>
>>> Perhaps we could think about allowing SMART commands to be written to
>>> disks when sysctl kern.securelevel >=2 ?
>>> (I assume smartmontools writes SMART commands)
>>>
>>
>> Sending raw disks commands is inherently insecure. It's hard to create a
>> list of those commands that are OK because of the complexity and diversity
>> of the needed functionality. That complexity also makes it hard to put the
>> commands into a series of ioctls which could be made more secure.
>>
>
> Thank you for your feedback Warner.
>
> Can't all SMART commands be easily identified among the others ? (when a
> command arrives, does kernel sees it is SMART flagged ?)
> Perhaps you assume some SMART commands may be dangerous for the disks'
> data itself ?
>

Yes. I do. They can be.

Warner



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