kernel-hardening - Re: [PATCH v6 7/8] Documentation: Add documentation for the Brute LSM

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Message-ID: <87k0q0l4s8.fsf@meer.lwn.net>
Date: Sun, 21 Mar 2021 12:50:47 -0600
From: Jonathan Corbet <corbet@....net>
To: John Wood <john.wood@....com>, Kees Cook <keescook@...omium.org>, Jann
 Horn <jannh@...gle.com>, Randy Dunlap <rdunlap@...radead.org>, James
 Morris <jmorris@...ei.org>, Shuah Khan <shuah@...nel.org>
Cc: John Wood <john.wood@....com>, "Serge E. Hallyn" <serge@...lyn.com>,
 Greg Kroah-Hartman <gregkh@...uxfoundation.org>, Andi Kleen
 <ak@...ux.intel.com>, kernel test robot <oliver.sang@...el.com>,
 linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org,
 linux-security-module@...r.kernel.org, linux-kselftest@...r.kernel.org,
 kernel-hardening@...ts.openwall.com
Subject: Re: [PATCH v6 7/8] Documentation: Add documentation for the Brute LSM

John Wood <john.wood@....com> writes:

> Add some info detailing what is the Brute LSM, its motivation, weak
> points of existing implementations, proposed solutions, enabling,
> disabling and self-tests.
>
> Signed-off-by: John Wood <john.wood@....com>
> ---
>  Documentation/admin-guide/LSM/Brute.rst | 278 ++++++++++++++++++++++++
>  Documentation/admin-guide/LSM/index.rst |   1 +
>  security/brute/Kconfig                  |   3 +-
>  3 files changed, 281 insertions(+), 1 deletion(-)
>  create mode 100644 Documentation/admin-guide/LSM/Brute.rst

Thanks for including documentation with the patch!

As you get closer to merging this, though, you'll want to take a minute
(OK, a few minutes) to build the docs and look at the result; there are
a number of places where you're not going to get what you expect.  Just
as an example:

[...]

> +Based on the above scenario it would be nice to have this detected and
> +mitigated, and this is the goal of this implementation. Specifically the
> +following attacks are expected to be detected:
> +
> +1.- Launching (fork()/exec()) a setuid/setgid process repeatedly until a
> +    desirable memory layout is got (e.g. Stack Clash).
> +2.- Connecting to an exec()ing network daemon (e.g. xinetd) repeatedly until a
> +    desirable memory layout is got (e.g. what CTFs do for simple network
> +    service).
> +3.- Launching processes without exec() (e.g. Android Zygote) and exposing state
> +    to attack a sibling.
> +4.- Connecting to a fork()ing network daemon (e.g. apache) repeatedly until the
> +    previously shared memory layout of all the other children is exposed (e.g.
> +    kind of related to HeartBleed).

Sphinx will try to recognize your enumerated list, but that may be a bit
more punctuation than it is prepared to deal with; I'd take the hyphens
out, if nothing else.

[...]

> +These statistics are hold by the brute_stats struct.
> +
> +struct brute_cred {
> +	kuid_t uid;
> +	kgid_t gid;
> +	kuid_t suid;
> +	kgid_t sgid;
> +	kuid_t euid;
> +	kgid_t egid;
> +	kuid_t fsuid;
> +	kgid_t fsgid;
> +};

That will certainly not render the way you want.  What you need here is
a literal block:

These statistics are hold by the brute_stats struct::

    struct brute_cred {
	kuid_t uid;
	kgid_t gid;
	kuid_t suid;
	kgid_t sgid;
	kuid_t euid;
	kgid_t egid;
	kuid_t fsuid;
	kgid_t fsgid;
    };

The "::" causes all of the indented text following to be formatted
literally. 

Thanks,

jon

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