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

On 06/03/2017 06:39 AM, Jann Horn wrote:

On Sat, Jun 3, 2017 at 7:53 AM, Matt Brown [off-list ref] wrote:

quoted

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)

[...]

quoted

Threat Models:

[...]

quoted

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.
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