Re: Memory Management during Program Loading

From: Sreeni (sreeni.pulichi_at_gmail.com)
Date: 06/28/05

  • Next message: David Masover: "Re: reiser4 plugins" 
    Date:	Tue, 28 Jun 2005 15:09:56 -0400
To: "Valdis.Kletnieks@vt.edu" <Valdis.Kletnieks@vt.edu>

    My main aim is to run a particular application in a known and fixed
    physical memory location. When kernel loads this binary, is there a
    way to force it to load at that fixed memory location. For example I
    always wanna run a program "hello_world.bin" from physical address
    location 0x007F_0000 to 0x007F_FFFF. I want my data, stack etc to be
    in this location only.

    The word "secure" is our internal terminology which seems to be bit confusing.

    Thanks
    Sreeni

    On 6/28/05, Valdis.Kletnieks@vt.edu <Valdis.Kletnieks@vt.edu> wrote:
    > On Tue, 28 Jun 2005 14:12:43 EDT, Sreeni said:
    >
    > > We have a "Bus Monitor hardware" which monitors and polices the bus at
    > > the specified physical address.
    >
    > What does this hardware do, exactly, in addition to the usual memory-protection
    > capabilities of the main processor? I suspect the answer to your query will
    > depend largely on what your monitor does, exactly, and what capabilities
    > it has, and what threat model you're trying to secure against....
    >
    > > Basically we need to run "secure" program under the supervision of the
    > > Bus monitor hardware.
    >
    > Is there an actual "threat model" here, as in "the attacker might try XYZ,
    > and this monitor is a defense because it does ABC, rendering XYZ ineffective"?
    >
    > I'm unclear on how the monitor can provide any *real* security when it quite
    > likely does *not* have access to the entire state of the system (in particular,
    > if there's a security-critical value that's still in a CPU register or L1
    > cache line...)
    >
    > > Kernel can see the "secure" memory region, and kernel is reponsible for enabling
    > > the "Bus monitor Hardware".
    >
    > The problem is that you're using an unsecured kernel to initially load the secure
    > memory region - so an attacker is free to load broken code into the secure
    > area. The usual "trusted system" solution for this is to ensure that the kernel
    > *also* runs inside the tamper-proof evironment....
    >
    > Or is the *real* question here "We have a bus analyzer that can't see all of
    > the physical memory, so we need the code we're interested in to be in the
    > part of physical memory it can see"? If that's the case, totally different
    > answers will probably apply (as we don't have to do things in a "secure" manner,
    > we just need to get the right pages in the right frames before the analyzer is
    > turned on).....
    >
    >
    > 

    -- 
~Sreeni
       -iDream
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