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    SubjectRe: [PATCH v5 0/6] Add support for O_MAYEXEC
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    On 05/05/2020 17:31, Mickaël Salaün wrote:
    > Hi,
    >
    > This fifth patch series add new kernel configurations (OMAYEXEC_STATIC,
    > OMAYEXEC_ENFORCE_MOUNT, and OMAYEXEC_ENFORCE_FILE) to enable to
    > configure the security policy at kernel build time. As requested by
    > Mimi Zohar, I completed the series with one of her patches for IMA.
    >
    > The goal of this patch series is to enable to control script execution
    > with interpreters help. A new O_MAYEXEC flag, usable through
    > openat2(2), is added to enable userspace script interpreter to delegate
    > to the kernel (and thus the system security policy) the permission to
    > interpret/execute scripts or other files containing what can be seen as
    > commands.
    >
    > A simple system-wide security policy can be enforced by the system
    > administrator through a sysctl configuration consistent with the mount
    > points or the file access rights. The documentation patch explains the
    > prerequisites.
    >
    > Furthermore, the security policy can also be delegated to an LSM, either
    > a MAC system or an integrity system. For instance, the new kernel
    > MAY_OPENEXEC flag closes a major IMA measurement/appraisal interpreter
    > integrity gap by bringing the ability to check the use of scripts [1].
    > Other uses are expected, such as for openat2(2) [2], SGX integration
    > [3], bpffs [4] or IPE [5].
    >
    > Userspace needs to adapt to take advantage of this new feature. For
    > example, the PEP 578 [6] (Runtime Audit Hooks) enables Python 3.8 to be
    > extended with policy enforcement points related to code interpretation,
    > which can be used to align with the PowerShell audit features.
    > Additional Python security improvements (e.g. a limited interpreter
    > withou -c, stdin piping of code) are on their way.
    >
    > The initial idea come from CLIP OS 4 and the original implementation has
    > been used for more than 12 years:
    > https://github.com/clipos-archive/clipos4_doc
    >
    > An introduction to O_MAYEXEC was given at the Linux Security Summit
    > Europe 2018 - Linux Kernel Security Contributions by ANSSI:
    > https://www.youtube.com/watch?v=chNjCRtPKQY&t=17m15s
    > The "write xor execute" principle was explained at Kernel Recipes 2018 -
    > CLIP OS: a defense-in-depth OS:
    > https://www.youtube.com/watch?v=PjRE0uBtkHU&t=11m14s
    >
    > This patch series can be applied on top of v5.7-rc4. This can be tested
    > with CONFIG_SYSCTL. I would really appreciate constructive comments on
    > this patch series.
    >
    > Previous version:
    > https://lore.kernel.org/lkml/20200428175129.634352-1-mic@digikod.net/

    The previous version (v4) is
    https://lore.kernel.org/lkml/20200430132320.699508-1-mic@digikod.net/

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