Re: [kernel-hardening] [PATCH v1 1/1] Add Trusted Path Execution as a stackable LSM

From	Matt Brown <matt@nmatt.com>
Newsgroups	linux.kernel
Subject	Re: [kernel-hardening] [PATCH v1 1/1] Add Trusted Path Execution as a stackable LSM
Date	2017-06-04 00:40 +0200
Message-ID	<tOpS9-4r2-5@gated-at.bofh.it> (permalink)
References	<tOagp-33Q-1@gated-at.bofh.it> <tOeDn-5QD-1@gated-at.bofh.it>
Organization	linux.* mail to news gateway

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On 06/03/2017 06:39 AM, Jann Horn wrote:
> On Sat, Jun 3, 2017 at 7:53 AM, Matt Brown <matt@nmatt.com> wrote:
>> This patch was modified from Brad Spengler's Trusted Path Execution (TPE)
>> feature in Grsecurity and also incorporates logging ideas from
>> cormander's tpe-lkm.
>>
>> Modifications from the Grsecurity implementation of TPE were made to
>> turn it into a stackable LSM using the existing LSM hook bprm_set_creds.
>> Also, denial messages were improved by including the full path of the
>> disallowed program. (This idea was taken from cormander's tpe-lkm)
> [...]
>> Threat Models:
> [...]
>> 2. Attacker on system replaces binary used by a privileged user with a
>>    malicious one
>>
>> *  This situation arises when administrator of a system leaves a binary
>>    as world writable.
>>
>> *  TPE is very effective against this threat model
>
> How do you end up with world-writable binaries in $PATH?
>

Sys Admin screw up. It also protects against world-writable binaries
anywhere on the system, not just in $PATH.

Thread

[PATCH v1 1/1] Add Trusted Path Execution as a stackable LSM Matt Brown <matt@nmatt.com> - 2017-06-03 08:00 +0200
  Re: [PATCH v1 1/1] Add Trusted Path Execution as a stackable LSM Al Viro <viro@ZenIV.linux.org.uk> - 2017-06-03 08:40 +0200
    Re: [PATCH v1 1/1] Add Trusted Path Execution as a stackable LSM Matt Brown <matt@nmatt.com> - 2017-06-04 07:30 +0200
      Re: [kernel-hardening] Re: [PATCH v1 1/1] Add Trusted Path Execution  as a stackable LSM Eric Biggers <ebiggers3@gmail.com> - 2017-06-04 07:50 +0200
        Re: [kernel-hardening] Re: [PATCH v1 1/1] Add Trusted Path Execution  as a stackable LSM Matt Brown <matt@nmatt.com> - 2017-06-04 14:50 +0200
      Re: [PATCH v1 1/1] Add Trusted Path Execution as a stackable LSM Al Viro <viro@ZenIV.linux.org.uk> - 2017-06-04 09:00 +0200
  Re: [kernel-hardening] [PATCH v1 1/1] Add Trusted Path Execution as a  stackable LSM Jann Horn <jannh@google.com> - 2017-06-03 12:40 +0200
    Re: [kernel-hardening] [PATCH v1 1/1] Add Trusted Path Execution as a  stackable LSM Matt Brown <matt@nmatt.com> - 2017-06-04 00:40 +0200
  Re: [kernel-hardening] [PATCH v1 1/1] Add Trusted Path Execution as a  stackable LSM Mickaël Salaün <mic@digikod.net> - 2017-06-04 18:50 +0200
    Re: [kernel-hardening] [PATCH v1 1/1] Add Trusted Path Execution as a  stackable LSM Mickaël Salaün <mic@digikod.net> - 2017-06-05 00:10 +0200

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