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    SubjectRe: [PATCH v6 00/12] implement KASLR for powerpc/fsl_booke/32
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    Hi Scott,

    On 2019/8/28 12:05, Scott Wood wrote:
    > On Fri, 2019-08-09 at 18:07 +0800, Jason Yan wrote:
    >> This series implements KASLR for powerpc/fsl_booke/32, as a security
    >> feature that deters exploit attempts relying on knowledge of the location
    >> of kernel internals.
    >>
    >> Since CONFIG_RELOCATABLE has already supported, what we need to do is
    >> map or copy kernel to a proper place and relocate.
    >
    > Have you tested this with a kernel that was loaded at a non-zero address? I
    > tried loading a kernel at 0x04000000 (by changing the address in the uImage,
    > and setting bootm_low to 04000000 in U-Boot), and it works without
    > CONFIG_RANDOMIZE and fails with.
    >

    How did you change the load address of the uImage, by changing the
    kernel config CONFIG_PHYSICAL_START or the "-a/-e" parameter of mkimage?
    I tried both, but it did not work with or without CONFIG_RANDOMIZE.


    Thanks,
    Jason

    >> Freescale Book-E
    >> parts expect lowmem to be mapped by fixed TLB entries(TLB1). The TLB1
    >> entries are not suitable to map the kernel directly in a randomized
    >> region, so we chose to copy the kernel to a proper place and restart to
    >> relocate.
    >>
    >> Entropy is derived from the banner and timer base, which will change every
    >> build and boot. This not so much safe so additionally the bootloader may
    >> pass entropy via the /chosen/kaslr-seed node in device tree.
    >
    > How complicated would it be to directly access the HW RNG (if present) that
    > early in the boot? It'd be nice if a U-Boot update weren't required (and
    > particularly concerning that KASLR would appear to work without a U-Boot
    > update, but without decent entropy).
    >
    > -Scott
    >
    >
    >
    > .
    >

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