[RFC,v9,16/16] documentation: add ipe documentation

Commit Message

Fan Wu Jan. 30, 2023, 10:57 p.m. UTC

From: Deven Bowers <[e-mail]>

Add IPE's admin and developer documentation to the kernel tree.

Co-developed-by: Fan Wu <[e-mail]>
Signed-off-by: Deven Bowers <[e-mail]>
Signed-off-by: Fan Wu <[e-mail]>
---
v2:
  + No Changes

v3:
  + Add Acked-by
  + Fixup code block syntax
  + Fix a minor grammatical issue.

v4:
  + Update documentation with the results of other
    code changes.

v5:
  + No changes

v6:
  + No changes

v7:
  + Add additional developer-level documentation
  + Update admin-guide docs to reflect changes.
  + Drop Acked-by due to significant changes
  + Added section about audit events in admin-guide

v8:
  + Correct terminology from "audit event" to "audit record"
  + Add associated documentation with the correct "audit event"
    terminology.
  + Add some context to the historical motivation for IPE and design
    philosophy.
  + Add some content about the securityfs layout in the policies
    directory.
  + Various spelling and grammatical corrections.

v9:
  + Correct spelling of "pitfalls"
  + Update the docs w.r.t the new parser and new audit formats
---
 Documentation/admin-guide/LSM/index.rst       |   1 +
 Documentation/admin-guide/LSM/ipe.rst         | 729 ++++++++++++++++++
 .../admin-guide/kernel-parameters.txt         |  12 +
 Documentation/security/index.rst              |   1 +
 Documentation/security/ipe.rst                | 436 +++++++++++
 MAINTAINERS                                   |   2 +
 6 files changed, 1181 insertions(+)
 create mode 100644 Documentation/admin-guide/LSM/ipe.rst
 create mode 100644 Documentation/security/ipe.rst

Comments

Bagas Sanjaya Jan. 31, 2023, 3:59 a.m. UTC | #1

On Mon, Jan 30, 2023 at 02:57:31PM -0800, Fan Wu wrote:
> diff --git a/Documentation/admin-guide/LSM/ipe.rst b/Documentation/admin-guide/LSM/ipe.rst
> new file mode 100644
> index 000000000000..b676cea62b2e
> --- /dev/null
> +++ b/Documentation/admin-guide/LSM/ipe.rst
> @@ -0,0 +1,729 @@
> +.. SPDX-License-Identifier: GPL-2.0
> +
> +Integrity Policy Enforcement (IPE)
> +==================================
> +
> +.. NOTE::
> +
> +   This is the documentation for admins, system builders, or individuals
> +   attempting to use IPE. If you're looking for more developer-focused
> +   documentation about IPE please see `Documentation/security/ipe.rst`
> +
> +Overview
> +--------
> +
> +IPE is a Linux Security Module which takes a complimentary approach to
> +access control. Whereas existing mandatory access control mechanisms
> +base their decisions on labels and paths, IPE instead determines
> +whether or not an operation should be allowed based on immutable
> +security properties of the system component the operation is being
> +performed on.
> +
> +IPE itself does not mandate how the security property should be
> +evaluated, but relies on an extensible set of external property providers
> +to evaluate the component. IPE makes its decision based on reference
> +values for the selected properties, specified in the IPE policy.
> +
> +The reference values represent the value that the policy writer and the
> +local system administrator (based on the policy signature) trust for the
> +system to accomplish the desired tasks.
> +
> +One such provider is for example dm-verity, which is able to represent
> +the integrity property of a partition (its immutable state) with a digest.
> +
> +IPE is compiled under ``CONFIG_SECURITY_IPE`` (Security -> Integrity Policy Enforcement (IPE)).
> +
> +Use Cases
> +---------
> +
> +IPE works best in fixed-function devices: devices in which their purpose
> +is clearly defined and not supposed to be changed (e.g. network firewall
> +device in a data center, an IoT device, etcetera), where all software and
> +configuration is built and provisioned by the system owner.
> +
> +IPE is a long-way off for use in general-purpose computing: the Linux
> +community as a whole tends to follow a decentralized trust model,
> +known as the web of trust, which IPE has no support for as of yet.
> +
> +IPE, instead of supporting web of trust, supports PKI, which generally
> +designates a set of entities that provide a measure of absolute trust.
> +
> +Additionally, while most packages are signed today, the files inside
> +the packages (for instance, the executables), tend to be unsigned. This
> +makes it difficult to utilize IPE in systems where a package manager is
> +expected to be functional, without major changes to the package manager
> +and ecosystem behind it.
> +
> +DIGLIM [#diglim]_ is a system that when combined with IPE, could be used to
> +enable general purpose computing scenarios.
> +
> +Known Gaps
> +----------
> +
> +IPE cannot verify the integrity of anonymous executable memory, such as
> +the trampolines created by gcc closures and libffi (<3.4.2), or JIT'd code.
> +Unfortunately, as this is dynamically generated code, there is no way
> +for IPE to ensure the integrity of this code to form a trust basis. In all
> +cases, the return result for these operations will be whatever the admin
> +configures as the ``DEFAULT`` action for ``EXECUTE``.
> +
> +IPE cannot verify the integrity of interpreted languages' programs when
> +these scripts are invoked via ``<interpreter> <file>``. This is because
> +the way interpreters execute these files, the scripts themselves are not
> +evaluated as executable code through one of IPE's hooks, as they are merely
> +files that are read (as opposed to executable code) [#interpreters]_.
> +
> +Threat Model
> +------------
> +
> +The threat type addressed by IPE is tampering of executable userspace
> +code beyond the initially booted kernel, and the initial verification of
> +kernel modules that are loaded in userspace through ``modprobe`` or
> +``insmod``.
> +
> +A bare-minimum example of a threat that should be mitigated by IPE, is
> +a hostile binary is downloaded with all required binaries (including
> +a loader, libc, etc). With IPE, this hostile binary should not able to
> +be executed, nor any of the downloaded binaries.
> +
> +Tampering violates integrity, and being unable to verify the integrity,
> +results in a lack of trust. IPE's role in mitigating this threat is to
> +verify the integrity (and authenticity) of all executable code and to
> +deny their use if they cannot be trusted (as integrity verification fails,
> +or the authorization check fails against the reference value in the policy).
> +IPE generates audit logs which may be utilized to detect failures resulting
> +from failure to pass policy.
> +
> +Tampering threat scenarios include modification or replacement of
> +executable code by a range of actors including:
> +
> +-  Actors with physical access to the hardware
> +-  Actors with local network access to the system
> +-  Actors with access to the deployment system
> +-  Compromised internal systems under external control
> +-  Malicious end users of the system
> +-  Compromised end users of the system
> +-  Remote (external) compromise of the system
> +
> +IPE does not mitigate threats arising from malicious authorized
> +developers (with access to a signing certificate), or compromised
> +developer tools used by authorized developers (i.e. Return Oriented
> +Programming attacks). Additionally, IPE draws hard security boundary
> +between userspace and kernelspace. As a result, IPE does not provide
> +any protections against a kernel level exploit, and a kernel-level
> +exploit can disable or tamper with IPE's protections.
> +
> +Policy
> +------
> +
> +IPE policy is a plain-text [#devdoc]_ policy composed of multiple statements
> +over several lines. There is one required line, at the top of the
> +policy, indicating the policy name, and the policy version, for
> +instance::
> +
> +   policy_name=Ex_Policy policy_version=0.0.0
> +
> +The policy name is a unique key identifying this policy in a human
> +readable name. This is used to create nodes under securityfs as well as
> +uniquely identify policies to deploy new policies vs update existing
> +policies.
> +
> +The policy version indicates the current version of the policy (NOT the
> +policy syntax version). This is used to prevent rollback of policy to
> +potentially insecure previous versions of the policy.
> +
> +The next portion of IPE policy are rules. Rules are formed by key=value
> +pairs, known as properties. IPE rules require two properties: "action",
> +which determines what IPE does when it encounters a match against the
> +rule, and "op", which determines when that rule should be evaluated.
> +The ordering is significant, a rule must start with "op", and end with
> +"action". Thus, a minimal rule is::
> +
> +   op=EXECUTE action=ALLOW
> +
> +This example will allow any execution. Additional properties are used to
> +restrict attributes about the files being evaluated. These properties
> +are intended to be descriptions of systems within the kernel that can
> +provide a measure of integrity verification, such that IPE can determine
> +the trust of the resource based on the "value" half of the property.
> +
> +Rules are evaluated top-to-bottom. As a result, any revocation rules,
> +or denies should be placed early in the file to ensure that these rules
> +are evaluated before a rule with "action=ALLOW" is hit.
> +
> +IPE policy supports comments. The character '#' will function as a
> +comment, ignoring all characters to the right of '#' until the newline.
> +
> +The default behavior of IPE evaluations can also be expressed in policy,
> +through the ``DEFAULT`` statement. This can be done at a global level,
> +or a per-operation level::
> +
> +   # Global
> +   DEFAULT action=ALLOW
> +
> +   # Operation Specific
> +   DEFAULT op=EXECUTE action=ALLOW
> +
> +A default must be set for all known operations in IPE. If you want to
> +preserve older policies being compatible with newer kernels that can introduce
> +new operations, please set a global default of 'ALLOW', and override the
> +defaults on a per-operation basis.
> +
> +With configurable policy-based LSMs, there's several issues with
> +enforcing the configurable policies at startup, around reading and
> +parsing the policy:
> +
> +1. The kernel *should* not read files from userspace, so directly reading
> +   the policy file is prohibited.
> +2. The kernel command line has a character limit, and one kernel module
> +   should not reserve the entire character limit for its own
> +   configuration.
> +3. There are various boot loaders in the kernel ecosystem, so handing
> +   off a memory block would be costly to maintain.
> +
> +As a result, IPE has addressed this problem through a concept of a "boot
> +policy". A boot policy is a minimal policy, compiled into the kernel.
> +This policy is intended to get the system to a state where userspace is
> +set up and ready to receive commands, at which point a more complex
> +policy can be deployed via securityfs. The boot policy can be specified
> +via the Kconfig, ``SECURITY_IPE_BOOT_POLICY``, which accepts a path to
> +a plain-text version of the IPE policy to apply. This policy will be
> +compiled into the kernel. If not specified, IPE will be disabled until
> +a policy is deployed and activated through securityfs.
> +
> +Deploying Policies
> +~~~~~~~~~~~~~~~~~~
> +
> +Policies can be deployed from userspace through securityfs. These policies
> +are signed through the PKCS#7 message format to enforce some level of
> +authorization of the policies (prohibiting an attacker from gaining
> +unconstrained root, and deploying an "allow all" policy). These
> +policies must be signed by a certificate that chains to the
> +``SYSTEM_TRUSTED_KEYRING``. Through openssl, the signing can be done via::
> +
> +   openssl smime -sign \
> +      -in "$MY_POLICY" \
> +      -signer "$MY_CERTIFICATE" \
> +      -inkey "$MY_PRIVATE_KEY" \
> +      -noattr \
> +      -nodetach \
> +      -nosmimecap \
> +      -outform der \
> +      -out "$MY_POLICY.p7b"
> +
> +Deploying the policies is done through securityfs, through the
> +``new_policy`` node. To deploy a policy, simply cat the file into the
> +securityfs node::
> +
> +   cat "$MY_POLICY.p7b" > /sys/kernel/security/ipe/new_policy
> +
> +Upon success, this will create one subdirectory under
> +``/sys/kernel/security/ipe/policies/``. The subdirectory will be the
> +``policy_name`` field of the policy deployed, so for the example above,
> +the directory will be ``/sys/kernel/security/ipe/policies/Ex_Policy``.
> +Within this directory, there will be five files: ``pkcs7``, ``policy``,
> +``active``, ``update``, and ``delete``.
> +
> +The ``pkcs7`` file is read only. Reading will provide the raw PKCS#7 data
> +that was provided to the kernel, representing the policy. Writing, will
> +deploy an in-place policy update.If the policy being read is the boot
> +policy, when read, this will return ENOENT, as this policy is not signed.
> +
> +The ``policy`` file is read only. Reading will provide the PKCS#7 inner
> +content of the policy, which will be the plain text policy.
> +
> +The ``active`` file is used to set a policy as the currently active policy.
> +This file is rw, and accepts a value of ``"1"`` to set the policy as active.
> +Since only a single policy can be active at one time, all other policies
> +will be marked inactive. The policy being marked active must have a policy
> +version greater or equal to the currently-running version.
> +
> +The ``update`` file is used to update a policy that is already present in
> +the kernel. This file is write-only and accepts a PKCS#7 signed policy.
> +One check will always be performed on this policy: the policy_names must
> +match with the updated version and the existing version. One additional check
> +may be made: If the policy being updated is the active policy, the updated
> +policy must have a policy version greater than or equal to the currently-running
> +version; This is to prevent rollback attacks.
> +
> +The ``delete`` file is used to remove a policy that is no longer needed.
> +This file is write-only and accepts a value of ``1`` to delete the policy.
> +On deletion, the securityfs node representing the policy will be removed.
> +The policy that is currently active cannot be deleted.
> +
> +Similarly, the writes to both ``update`` and ``new_policy`` above will
> +result in an error upon syntactically invalid or untrusted policies.
> +In the case of ``new_policy``, it will also error if a policy already
> +exists with the same ``policy_name``.
> +
> +Deploying these policies will *not* cause IPE to start enforcing this
> +policy. Once deployment is successful, a policy can be marked as active,
> +via ``/sys/kernel/security/ipe/$policy_name/active``. IPE will enforce
> +whatever policy is marked as active. For our example, we can activate
> +the ``Ex_Policy`` via::
> +
> +   echo 1 > "/sys/kernel/security/ipe/Ex_Policy/active"
> +
> +At which point, ``Ex_Policy`` will now be the enforced policy on the
> +system.
> +
> +IPE also provides a way to delete policies. This can be done via the
> +``delete`` securityfs node, ``/sys/kernel/security/ipe/$policy_name/delete``.
> +Writing ``1`` to that file will delete that node::
> +
> +   echo 1 > "/sys/kernel/security/ipe/$policy_name/delete"
> +
> +There is only one requirement to delete a policy:
> +
> +1. The policy being deleted must not be the active policy.
> +
> +.. NOTE::
> +
> +   If a traditional MAC system is enabled (SELinux, apparmor, smack), all
> +   writes to ipe's securityfs nodes require ``CAP_MAC_ADMIN``.
> +
> +Modes
> +~~~~~
> +
> +IPE supports two modes of operation: permissive (similar to SELinux's
> +permissive mode) and enforce. Permissive mode performs the same checks
> +as enforce mode, and logs policy violations, but will not enforce the
> +policy. This allows users to test policies before enforcing them.
> +
> +The default mode is enforce, and can be changed via the kernel command
> +line parameter ``ipe.enforce=(0|1)``, or the securityfs node
> +``/sys/kernel/security/ipe/enforce``.
> +
> +.. NOTE::
> +
> +   If a traditional MAC system is enabled (SELinux, apparmor, smack, etcetera),
> +   all writes to ipe's securityfs nodes require ``CAP_MAC_ADMIN``.
> +
> +Audit Events
> +~~~~~~~~~~~~
> +
> +1420 AUDIT_IPE_ACCESS
> +^^^^^^^^^^^^^^^^^^^^^
> +Event Examples::
> +
> +   type=1420 audit(1653364370.067:61): path="/root/fs/rw/plain/execve" dev="vdc1" ino=16 rule="DEFAULT op=EXECUTE action=DENY"
> +   type=1300 audit(1653364370.067:61): arch=c000003e syscall=10 success=no exit=-13 a0=7f0bf0644000 a1=4f80 a2=5 a3=7f0bf043d300 items=0 ppid=455 pid=737 auid=0 uid=0 gid=0 euid=0 suid=0 fsuid=0 egid=0 sgid=0 fsgid=0 tty=ttyS0 ses=3 comm="mprotect" exe="/root/host/mprotect" subj=kernel key=(null)
> +   type=1327 audit(1653364370.067:61): proctitle=686F73742F6D70726F7465637400534800527C5700527C5800706C61696E2F657865637665
> +
> +   type=1420 audit(1653364735.161:64): rule="DEFAULT op=EXECUTE action=DENY"
> +   type=1300 audit(1653364735.161:64): arch=c000003e syscall=9 success=no exit=-13 a0=0 a1=1000 a2=4 a3=20 items=0 ppid=455 pid=774 auid=0 uid=0 gid=0 euid=0 suid=0 fsuid=0 egid=0 sgid=0 fsgid=0 tty=ttyS0 ses=3 comm="mmap" exe="/root/host/mmap" subj=kernel key=(null)
> +   type=1327 audit(1653364735.161:64): proctitle=686F73742F6D6D617000410058⏎
> +
> +This event indicates that IPE made an access control decision; the IPE specific
> +record (1420) will always be emitted in conjunction with a ``AUDITSYSCALL`` record.
> +
> +Determining whether IPE is in permissive can be derived from the success and exit
> +field of the AUDITSYSCALL record
> +
> +
> +
> +Field descriptions:
> +
> ++---------------+------------+-----------+-------------------------------------------------------------------------+
> +| Field         | Value Type | Optional? | Description of Value                                                    |
> ++===============+============+===========+=========================================================================+
> +| path          | string     | Yes       | The absolute path to the file that was the subject of the evaluation    |
> ++---------------+------------+-----------+-------------------------------------------------------------------------+
> +| ino           | integer    | Yes       | The inode number of the file that was the subject of the evaluation     |
> ++---------------+------------+-----------+-------------------------------------------------------------------------+
> +| dev           | string     | Yes       | The device name that the file under evaluation belongs to, e.g. vda     |
> ++---------------+------------+-----------+-------------------------------------------------------------------------+
> +| rule          | string     | No        | The exact rule in IPE's policy that the evaluation matched              |
> ++---------------+------------+-----------+-------------------------------------------------------------------------+
> +
> +1403 AUDIT_MAC_POLICY_LOAD
> +^^^^^^^^^^^^^^^^^^^^^^^^^^
> +
> +Event Example::
> +
> +   type=1403 audit(1653425529.927:53): policy_name="dmverity_roothash" policy_version=0.0.0 sha256=DC67AC19E05894EFB3170A8E55DE529794E248C2 auid=4294967295 ses=4294967295 lsm=ipe res=1
> +   type=1300 audit(1653425529.927:53): arch=c000003e syscall=1 success=yes exit=2567 a0=3 a1=5596fcae1fb0 a2=a07 a3=2 items=0 ppid=184 pid=229 auid=4294967295 uid=0 gid=0 euid=0 suid=0 fsuid=0 egid=0 sgid=0 fsgid=0 tty=pts0 ses=4294967295 comm="python3" exe="/usr/bin/python3.10" key=(null)
> +   type=1327 audit(1653425529.927:53): PROCTITLE proctitle=707974686F6E3300746573742F6D61696E2E7079002D66002E2E
> +
> +This record will always be emitted in conjunction with a ``AUDITSYSCALL`` record for the ``write`` syscall.
> +
> ++----------------+------------+-----------+--------------------------------------------------------------+
> +| Field          | Value Type | Optional? | Description of Value                                         |
> ++================+============+===========+==============================================================+
> +| policy_name    | string     | No        | The policy_name field of the policy.                         |
> ++----------------+------------+-----------+--------------------------------------------------------------+
> +| policy_version | string     | No        | The policy_version field of the policy                       |
> ++----------------+------------+-----------+--------------------------------------------------------------+
> +| sha256         | string     | Yes*      | A flat hash of the policy. Can be used to identify a policy. |
> ++----------------+------------+-----------+--------------------------------------------------------------+
> +| auid           | integer    | No        | The audit user ID.                                           |
> ++----------------+------------+-----------+--------------------------------------------------------------+
> +| ses            | integer    | No        | The session ID.                                              |
> ++----------------+------------+-----------+--------------------------------------------------------------+
> +| lsm            | string     | No        | The lsm name associated with the event.                      |
> ++----------------+------------+-----------+--------------------------------------------------------------+
> +| res            | integer    | No        | The operation result.                                        |
> ++----------------+------------+-----------+--------------------------------------------------------------+
> +
> +1405 AUDIT_MAC_CONFIG_CHANGE
> +^^^^^^^^^^^^^^^^^^^^^^^^^^^^
> +
> +Event Example::
> +
> +   type=1405 audit(1653425583.136:54): old_active_pol_name="Allow_All" old_active_pol_version=0.0.0 old_sha256=DA39A3EE5E6B4B0D3255BFEF95601890AFD80709 new_active_pol_name="dmverity_roothash" new_active_pol_version=0.0.0 new_sha256=DC67AC19E05894EFB3170A8E55DE529794E248C2 auid=4294967295 ses=4294967295 lsm=ipe res=1
> +   type=1300 audit(1653425583.136:54): SYSCALL arch=c000003e syscall=1 success=yes exit=2 a0=3 a1=5596fcae1fb0 a2=2 a3=2 items=0 ppid=184 pid=229 auid=4294967295 uid=0 gid=0 euid=0 suid=0 fsuid=0 egid=0 sgid=0 fsgid=0 tty=pts0 ses=4294967295 comm="python3" exe="/usr/bin/python3.10" key=(null)
> +   type=1327 audit(1653425583.136:54): PROCTITLE proctitle=707974686F6E3300746573742F6D61696E2E7079002D66002E2
> +
> +This record will always be emitted in conjunction with a ``AUDITSYSCALL`` record for the ``write`` syscall.
> +
> ++------------------------+------------+-----------+----------------------------------------------------+
> +| Field                  | Value Type | Optional? | Description of Value                               |
> ++========================+============+===========+====================================================+
> +| old_active_pol_name    | string     | No        | The policy_name field of the old active policy.    |
> ++------------------------+------------+-----------+----------------------------------------------------+
> +| old_active_pol_version | string     | No        | The policy_version field of the old active policy. |
> ++------------------------+------------+-----------+----------------------------------------------------+
> +| old_sha256             | string     | Yes*      | A flat hash of the old active policy.              |
> ++------------------------+------------+-----------+----------------------------------------------------+
> +| new_active_pol_name    | string     | No        | The policy_name field of the new active policy.    |
> ++------------------------+------------+-----------+----------------------------------------------------+
> +| new_active_pol_version | string     | No        | The policy_version field of the new active policy. |
> ++------------------------+------------+-----------+----------------------------------------------------+
> +| new_sha256             | string     | Yes*      | A flat hash of the new active policy.              |
> ++------------------------+------------+-----------+----------------------------------------------------+
> +| auid                   | integer    | No        | The audit user ID.                                 |
> ++------------------------+------------+-----------+----------------------------------------------------+
> +| ses                    | integer    | No        | The session ID.                                    |
> ++------------------------+------------+-----------+----------------------------------------------------+
> +| lsm                    | string     | No        | The lsm name associated with the event.            |
> ++------------------------+------------+-----------+----------------------------------------------------+
> +| res                    | integer    | No        | The operation result.                              |
> ++------------------------+------------+-----------+----------------------------------------------------+
> +
> +1404 AUDIT_MAC_STATUS
> +^^^^^^^^^^^^^^^^^^^^^
> +
> +Event Examples::
> +
> +   type=1404 audit(1653425689.008:55): permissive=1 auid=0 ses=4294967295 lsm=ipe res=1
> +   type=1300 audit(1653425689.008:55): arch=c000003e syscall=1 success=yes exit=2 a0=1 a1=55c1065e5c60 a2=2 a3=0 items=0 ppid=405 pid=441 auid=0 uid=0 gid=0 euid=0 suid=0 fsuid=0 egid=0 sgid=)
> +   type=1327 audit(1653425689.008:55): proctitle="-bash"
> +
> +   type=1404 audit(1653425689.008:55): permissive=0 auid=0 ses=4294967295 lsm=ipe res=1
> +   type=1300 audit(1653425689.008:55): arch=c000003e syscall=1 success=yes exit=2 a0=1 a1=55c1065e5c60 a2=2 a3=0 items=0 ppid=405 pid=441 auid=0 uid=0 gid=0 euid=0 suid=0 fsuid=0 egid=0 sgid=)
> +   type=1327 audit(1653425689.008:55): proctitle="-bash"
> +
> +This record will always be emitted in conjunction with a ``AUDITSYSCALL`` record for the ``write`` syscall.
> +
> ++------------+------------+-----------+-------------------------------------------------------------------+
> +| Field      | Value Type | Optional? | Description of Value                                              |
> ++============+============+===========+===================================================================+
> +| permissive | integer    | No        | The state IPE is being switched to. 1 is permissive, 0 is enforce |
> ++------------+------------+-----------+-------------------------------------------------------------------+
> +| auid       | integer    | No        | The audit user ID.                                                |
> ++------------+------------+-----------+-------------------------------------------------------------------+
> +| ses        | integer    | No        | The session ID.                                                   |
> ++------------+------------+-----------+-------------------------------------------------------------------+
> +| lsm        | string     | No        | The lsm name associated with the event.                           |
> ++------------+------------+-----------+-------------------------------------------------------------------+
> +| res        | integer    | No        | The operation result.                                             |
> ++------------+------------+-----------+-------------------------------------------------------------------+
> +
> +Success Auditing
> +^^^^^^^^^^^^^^^^
> +
> +IPE supports success auditing. When enabled, all events that pass IPE
> +policy and are not blocked will emit an audit event. This is disabled by
> +default, and can be enabled via the kernel command line
> +``ipe.success_audit=(0|1)`` or the securityfs node,
> +``/sys/kernel/security/ipe/success_audit``.
> +
> +This is *very* noisy, as IPE will check every userspace binary on the
> +system, but is useful for debugging policies.
> +
> +.. NOTE::
> +
> +   If a traditional MAC system is enabled (SELinux, apparmor, smack, etcetera),
> +   all writes to ipe's securityfs nodes require ``CAP_MAC_ADMIN``.
> +
> +Properties
> +----------
> +
> +As explained above, IPE properties are ``key=value`` pairs expressed in
> +IPE policy. Two properties are built-into the policy parser: 'op' and
> +'action'. The other properties are determinstic attributes to express
> +across files. Currently those properties are: '``boot_verified``',
> +'``dmverity_signature``', '``dmverity_roothash``', '``fsverity_signature``',
> +'``fsverity_digest``'. A description of all properties supported by IPE
> +are listed below:
> +
> +op
> +~~
> +
> +Indicates the operation for a rule to apply to. Must be in every rule,
> +as the first token. IPE supports the following operations:
> +
> +   ``EXECUTE``
> +
> +      Pertains to any file attempting to be executed, or loaded as an
> +      executable.
> +
> +   ``FIRMWARE``:
> +
> +      Pertains to firmware being loaded via the firmware_class interface.
> +      This covers both the preallocated buffer and the firmware file
> +      itself.
> +
> +   ``KMODULE``:
> +
> +      Pertains to loading kernel modules via ``modprobe`` or ``insmod``.
> +
> +   ``KEXEC_IMAGE``:
> +
> +      Pertains to kernel images loading via ``kexec``.
> +
> +   ``KEXEC_INITRAMFS``
> +
> +      Pertains to initrd images loading via ``kexec --initrd``.
> +
> +   ``POLICY``:
> +
> +      Controls loading polcies via reading a kernel-space initiated read.
> +
> +      An example of such is loading IMA policies by writing the path
> +      to the policy file to ``$securityfs/ima/policy``
> +
> +   ``X509_CERT``:
> +
> +      Controls loading IMA certificates through the Kconfigs,
> +      ``CONFIG_IMA_X509_PATH`` and ``CONFIG_EVM_X509_PATH``.
> +
> +action
> +~~~~~~
> +
> +   Determines what IPE should do when a rule matches. Must be in every
> +   rule, as the final clause. Can be one of:
> +
> +   ``ALLOW``:
> +
> +      If the rule matches, explicitly allow access to the resource to proceed
> +      without executing any more rules.
> +
> +   ``DENY``:
> +
> +      If the rule matches, explicitly prohibit access to the resource to
> +      proceed without executing any more rules.
> +
> +boot_verified
> +~~~~~~~~~~~~~
> +
> +   This property can be utilized for authorization of the first super-block
> +   that executes a file. This is almost always init. Typically this is used
> +   for systems with an initramfs or other initial disk, where this is unmounted
> +   before the system becomes available, and is not covered by any other property.
> +   The format of this property is::
> +
> +         boot_verified=(TRUE|FALSE)
> +
> +
> +   .. WARNING::
> +
> +      This property will trust any disk where the first execution evaluation
> +      occurs. If you do *NOT* have a startup disk that is unpacked and unmounted
> +      (like initramfs), then it will automatically trust the root filesystem and
> +      potentially overauthorize the entire disk.
> +
> +dmverity_roothash
> +~~~~~~~~~~~~~~~~~
> +
> +   This property can be utilized for authorization or revocation of
> +   specific dm-verity volumes, identified via root hash. It has a
> +   dependency on the DM_VERITY module. This property is controlled by the
> +   Kconfig ``CONFIG_IPE_PROP_DM_VERITY``. The format of this property
> +   is::
> +
> +      dmverity_roothash=DigestName:HexadecimalString
> +
> +   The supported DigestNames for dmverity_roothash are [#dmveritydigests]_ [#securedigest]_ :
> +
> +      + blake2b-512
> +      + blake2s-256
> +      + sha1
> +      + sha256
> +      + sha384
> +      + sha512
> +      + sha3-224
> +      + sha3-256
> +      + sha3-384
> +      + sha3-512
> +      + md4
> +      + md5
> +      + sm3
> +      + rmd160
> +
> +dmverity_signature
> +~~~~~~~~~~~~~~~~~~
> +
> +   This property can be utilized for authorization of all dm-verity volumes
> +   that have a signed roothash that chains to a keyring specified by dm-verity's
> +   configuration, either the system trusted keyring, or the secondary keyring.
> +   It has an additional dependency on the ``DM_VERITY_VERIFY_ROOTHASH_SIG``
> +   Kconfig. This property is controlled by the Kconfig
> +   ``CONFIG_IPE_PROP_DM_VERITY``. The format of this property is::
> +
> +      dmverity_signature=(TRUE|FALSE)
> +
> +fsverity_digest
> +~~~~~~~~~~~~~~~
> +
> +   This property can be utilized for authorization or revocation of
> +   specific fsverity enabled file, identified via its fsverity digest.
> +   It has a dependency on the FS_VERITY module. This property is
> +   controlled by the Kconfig ``CONFIG_IPE_PROP_FS_VERITY``.
> +   The format of this property is::
> +
> +      fsverity_digest=DigestName:HexadecimalString
> +
> +   The supported DigestNames for dmverity_roothash are [#fsveritydigest] [#securedigest]_ :
> +
> +      + sha256
> +      + sha512
> +
> +fsverity_signature
> +~~~~~~~~~~~~~~~~~~
> +
> +Version 1
> +
> +   This property can be utilized for authorization of all fsverity enabled
> +   files that is verified by fsverity. The keyring that the signature is
> +   verified against is subject to fsverity's configuration, typically the fsverity
> +   keyring. It has a dependency on the ``CONFIG_FS_VERITY_BUILTIN_SIGNATURES``
> +   Kconfig. This property is controlled by the Kconfig
> +   ``CONFIG_IPE_PROP_FS_VERITY``. The format of this property is::
> +
> +      fsverity_signature=(TRUE|FALSE)
> +
> +Policy Examples
> +---------------
> +
> +Allow all
> +~~~~~~~~~
> +
> +::
> +
> +   policy_name=Allow_All policy_version=0.0.0
> +   DEFAULT action=ALLOW
> +
> +Allow only initial superblock
> +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> +
> +::
> +
> +   policy_name=Allow_All_Initial_SB policy_version=0.0.0
> +   DEFAULT action=DENY
> +
> +   op=EXECUTE boot_verified=TRUE action=ALLOW
> +
> +Allow any signed dm-verity volume and the initial superblock
> +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> +
> +::
> +
> +   policy_name=AllowSignedAndInitial policy_version=0.0.0
> +   DEFAULT action=DENY
> +
> +   op=EXECUTE boot_verified=TRUE action=ALLOW
> +   op=EXECUTE dmverity_signature=TRUE action=ALLOW
> +
> +Prohibit execution from a specific dm-verity volume
> +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> +
> +::
> +
> +   policy_name=AllowSignedAndInitial policy_version=0.0.0
> +   DEFAULT action=DENY
> +
> +   op=EXECUTE dmverity_roothash=sha256:cd2c5bae7c6c579edaae4353049d58eb5f2e8be0244bf05345bc8e5ed257baff action=DENY
> +
> +   op=EXECUTE boot_verified=TRUE action=ALLOW
> +   op=EXECUTE dmverity_signature=TRUE action=ALLOW
> +
> +Allow only a specific dm-verity volume
> +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> +
> +::
> +
> +   policy_name=AllowSignedAndInitial policy_version=0.0.0
> +   DEFAULT action=DENY
> +
> +   op=EXECUTE dmverity_roothash=sha256:401fcec5944823ae12f62726e8184407a5fa9599783f030dec146938 action=ALLOW
> +
> +Allow any signed fs-verity file
> +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> +
> +::
> +
> +   policy_name=AllowSignedFSVerity policy_version=0.0.0
> +   DEFAULT action=DENY
> +
> +   op=EXECUTE fsverity_signature=TRUE action=ALLOW
> +
> +Prohibit execution of a specific fs-verity file
> +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> +
> +::
> +
> +   policy_name=ProhibitSpecificFSVF policy_version=0.0.0
> +   DEFAULT action=DENY
> +
> +   op=EXECUTE fsverity_digest=sha256:fd88f2b8824e197f850bf4c5109bea5cf0ee38104f710843bb72da796ba5af9e action=DENY
> +   op=EXECUTE boot_verified=TRUE action=ALLOW
> +   op=EXECUTE dmverity_signature=TRUE action=ALLOW
> +
> +Additional Information
> +----------------------
> +
> +- `Github Repository <https://github.com/microsoft/ipe>`_
> +- `Design Documentation </security/ipe>`_
> +
> +FAQ
> +---
> +
> +Q:
> +   What's the difference between other LSMs which provide a measure of
> +   trust-based access control?
> +
> +A:
> +
> +   In general, there's two other LSMs that can provide similar functionality:
> +   IMA, and Loadpin.
> +
> +   IMA and IPE are functionally very similar. The significant difference between
> +   the two is the policy. [#devdoc]_
> +
> +   Loadpin and IPE differ fairly dramatically, as Loadpin controls only the IPE
> +   equivalent of ``KERNEL_READ``, whereas IPE is capable of controlling execution,
> +   on top of ``KERNEL_READ``. The trust model is also different; Loadpin roots its
> +   trust in the initial super-block, instead, IPE roots its trust in the kernel
> +   itself (via ``SYSTEM_TRUSTED_KEYS``).
> +
> +-----------
> +
> +.. [#diglim] 1: https://lore.kernel.org/bpf/[e-mail]/T/
> +
> +.. [#interpreters] There is `some interest in solving this issue <https://lore.kernel.org/lkml/[e-mail]/>`_.
> +
> +.. [#devdoc] Please see `Documentation/security/ipe.rst` for more on this topic.
> +
> +.. [#fsveritydigest] These hash algorithms are based on values accepted by fsverity-utils;
> +                     IPE does not impose any restrictions on the digest algorithm itself;
> +                     thus, this list may be out of date.
> +
> +.. [#dmveritydigests] These hash algorithms are based on values accepted by dm-verity,
> +                      specifically ``crypto_alloc_ahash`` in ``verity_ctr``; ``veritysetup``
> +                      does support more algorithms than the list above. IPE does not impose
> +                      any restrictions on the digest algorithm itself; thus, this list
> +                      may be out of date.
> +
> +.. [#securedigest] Please ensure you are using cryptographically secure hash functions;
> +                   just because something is *supported* does not mean it is *secure*.

What about wordings below instead?

---- >8 ----
diff --git a/Documentation/admin-guide/LSM/ipe.rst b/Documentation/admin-guide/LSM/ipe.rst
index b676cea62b2e74..8b1d4eb0ebf19f 100644
--- a/Documentation/admin-guide/LSM/ipe.rst
+++ b/Documentation/admin-guide/LSM/ipe.rst
@@ -31,7 +31,9 @@ system to accomplish the desired tasks.
 One such provider is for example dm-verity, which is able to represent
 the integrity property of a partition (its immutable state) with a digest.
 
-IPE is compiled under ``CONFIG_SECURITY_IPE`` (Security -> Integrity Policy Enforcement (IPE)).
+To enable IPE, ensure that ``CONFIG_SECURITY_IPE`` (under
+:menuselection:`Security -> Integrity Policy Enforcement (IPE)`) config
+option is enabled.
 
 Use Cases
 ---------
@@ -42,11 +44,10 @@ device in a data center, an IoT device, etcetera), where all software and
 configuration is built and provisioned by the system owner.
 
 IPE is a long-way off for use in general-purpose computing: the Linux
-community as a whole tends to follow a decentralized trust model,
-known as the web of trust, which IPE has no support for as of yet.
-
-IPE, instead of supporting web of trust, supports PKI, which generally
-designates a set of entities that provide a measure of absolute trust.
+community as a whole tends to follow a decentralized trust model (known as
+the web of trust), which IPE has no support for it yet. Instead, IPE
+supports PKI (public key infrastructure), which generally designates a
+set of trusted entities that provide a measure of absolute trust.
 
 Additionally, while most packages are signed today, the files inside
 the packages (for instance, the executables), tend to be unsigned. This
@@ -55,10 +56,10 @@ expected to be functional, without major changes to the package manager
 and ecosystem behind it.
 
 DIGLIM [#diglim]_ is a system that when combined with IPE, could be used to
-enable general purpose computing scenarios.
+enable and support general-purpose computing use cases.
 
-Known Gaps
-----------
+Known Limitations
+-----------------
 
 IPE cannot verify the integrity of anonymous executable memory, such as
 the trampolines created by gcc closures and libffi (<3.4.2), or JIT'd code.
@@ -67,11 +68,12 @@ for IPE to ensure the integrity of this code to form a trust basis. In all
 cases, the return result for these operations will be whatever the admin
 configures as the ``DEFAULT`` action for ``EXECUTE``.
 
-IPE cannot verify the integrity of interpreted languages' programs when
-these scripts are invoked via ``<interpreter> <file>``. This is because
-the way interpreters execute these files, the scripts themselves are not
-evaluated as executable code through one of IPE's hooks, as they are merely
-files that are read (as opposed to executable code) [#interpreters]_.
+IPE cannot verify the integrity of programs written in interpreted
+languages when these scripts are invoked by passing these program files
+to the interpreter. This is because the way interpreters execute these
+files; the scripts themselves are not evaluated as executable code
+through one of IPE's hooks, but they are merely text files that are read
+(as opposed to compiled executables) [#interpreters]_.
 
 Threat Model
 ------------
@@ -82,17 +84,19 @@ kernel modules that are loaded in userspace through ``modprobe`` or
 ``insmod``.
 
 A bare-minimum example of a threat that should be mitigated by IPE, is
-a hostile binary is downloaded with all required binaries (including
-a loader, libc, etc). With IPE, this hostile binary should not able to
-be executed, nor any of the downloaded binaries.
+an untrusted (potentially malicious) binary that is downloaded and
+bundled with all required dependencies (including a loader, libc, etc).
+With IPE, this binary should not be allowed to be executed, not even any
+of its dependencies.
 
-Tampering violates integrity, and being unable to verify the integrity,
-results in a lack of trust. IPE's role in mitigating this threat is to
-verify the integrity (and authenticity) of all executable code and to
-deny their use if they cannot be trusted (as integrity verification fails,
-or the authorization check fails against the reference value in the policy).
-IPE generates audit logs which may be utilized to detect failures resulting
-from failure to pass policy.
+Tampering violates integrity, yet lack of trust is caused by being
+unable to detect tampering (and by extent verifying the integrity).
+IPE's role in mitigating this threat is to verify the integrity (and
+authenticity) of all executable code and to deny their use if they
+cannot be trusted (as integrity verification fails, or the authorization
+check fails against the reference value in the policy). IPE generates
+audit logs which may be utilized to detect and analyze failures
+resulting from policy violation.
 
 Tampering threat scenarios include modification or replacement of
 executable code by a range of actors including:
@@ -105,13 +109,13 @@ executable code by a range of actors including:
 -  Compromised end users of the system
 -  Remote (external) compromise of the system
 
-IPE does not mitigate threats arising from malicious authorized
+IPE does not mitigate threats arising from malicious but authorized
 developers (with access to a signing certificate), or compromised
-developer tools used by authorized developers (i.e. Return Oriented
-Programming attacks). Additionally, IPE draws hard security boundary
-between userspace and kernelspace. As a result, IPE does not provide
-any protections against a kernel level exploit, and a kernel-level
-exploit can disable or tamper with IPE's protections.
+developer tools used by them (i.e. return-oriented programming attacks).
+Additionally, IPE draws hard security boundary between userspace and
+kernelspace. As a result, IPE does not provide any protections against a
+kernel level exploit, and a kernel-level exploit can disable or tamper
+with IPE's protections.
 
 Policy
 ------
@@ -133,11 +137,11 @@ policy syntax version). This is used to prevent rollback of policy to
 potentially insecure previous versions of the policy.
 
 The next portion of IPE policy are rules. Rules are formed by key=value
-pairs, known as properties. IPE rules require two properties: "action",
+pairs, known as properties. IPE rules require two properties: ``action``,
 which determines what IPE does when it encounters a match against the
-rule, and "op", which determines when that rule should be evaluated.
-The ordering is significant, a rule must start with "op", and end with
-"action". Thus, a minimal rule is::
+rule, and ``op``, which determines when the rule should be evaluated.
+The ordering is significant, a rule must start with ``op``, and end with
+``action``. Thus, a minimal rule is::
 
    op=EXECUTE action=ALLOW
 
@@ -145,14 +149,14 @@ This example will allow any execution. Additional properties are used to
 restrict attributes about the files being evaluated. These properties
 are intended to be descriptions of systems within the kernel that can
 provide a measure of integrity verification, such that IPE can determine
-the trust of the resource based on the "value" half of the property.
+the trust of the resource based on the value of the property.
 
 Rules are evaluated top-to-bottom. As a result, any revocation rules,
 or denies should be placed early in the file to ensure that these rules
-are evaluated before a rule with "action=ALLOW" is hit.
+are evaluated before a rule with ``action=ALLOW``.
 
-IPE policy supports comments. The character '#' will function as a
-comment, ignoring all characters to the right of '#' until the newline.
+IPE policy supports comments. Any line which is prefixed with ``#`` will
+be ignored.
 
 The default behavior of IPE evaluations can also be expressed in policy,
 through the ``DEFAULT`` statement. This can be done at a global level,
@@ -166,8 +170,8 @@ or a per-operation level::
 
 A default must be set for all known operations in IPE. If you want to
 preserve older policies being compatible with newer kernels that can introduce
-new operations, please set a global default of 'ALLOW', and override the
-defaults on a per-operation basis.
+new operations, set a global default of ``ALLOW``, then override the
+defaults on a per-operation basis (as above).
 
 With configurable policy-based LSMs, there's several issues with
 enforcing the configurable policies at startup, around reading and
@@ -182,14 +186,14 @@ parsing the policy:
    off a memory block would be costly to maintain.
 
 As a result, IPE has addressed this problem through a concept of a "boot
-policy". A boot policy is a minimal policy, compiled into the kernel.
-This policy is intended to get the system to a state where userspace is
-set up and ready to receive commands, at which point a more complex
-policy can be deployed via securityfs. The boot policy can be specified
-via the Kconfig, ``SECURITY_IPE_BOOT_POLICY``, which accepts a path to
-a plain-text version of the IPE policy to apply. This policy will be
-compiled into the kernel. If not specified, IPE will be disabled until
-a policy is deployed and activated through securityfs.
+policy". A boot policy is a minimal policy which is compiled into the
+kernel. This policy is intended to get the system to a state where
+userspace is set up and ready to receive commands, at which point a more
+complex policy can be deployed via securityfs. The boot policy can be
+specified via ``SECURITY_IPE_BOOT_POLICY`` config option, which accepts
+a path to a plain-text version of the IPE policy to apply. This policy
+will be compiled into the kernel. If not specified, IPE will be disabled
+until a policy is deployed and activated through securityfs.
 
 Deploying Policies
 ~~~~~~~~~~~~~~~~~~
@@ -199,7 +203,7 @@ are signed through the PKCS#7 message format to enforce some level of
 authorization of the policies (prohibiting an attacker from gaining
 unconstrained root, and deploying an "allow all" policy). These
 policies must be signed by a certificate that chains to the
-``SYSTEM_TRUSTED_KEYRING``. Through openssl, the signing can be done via::
+``SYSTEM_TRUSTED_KEYRING``. With openssl, the policy can be signed by::
 
    openssl smime -sign \
       -in "$MY_POLICY" \
@@ -224,12 +228,12 @@ the directory will be ``/sys/kernel/security/ipe/policies/Ex_Policy``.
 Within this directory, there will be five files: ``pkcs7``, ``policy``,
 ``active``, ``update``, and ``delete``.
 
-The ``pkcs7`` file is read only. Reading will provide the raw PKCS#7 data
+The ``pkcs7`` file is read-only. Reading it returns the raw PKCS#7 data
 that was provided to the kernel, representing the policy. Writing, will
-deploy an in-place policy update.If the policy being read is the boot
-policy, when read, this will return ENOENT, as this policy is not signed.
+deploy an in-place policy update. If the policy being read is the boot
+policy, this will return ``ENOENT``, as it is is not signed.
 
-The ``policy`` file is read only. Reading will provide the PKCS#7 inner
+The ``policy`` file is read-only. Reading it returns the PKCS#7 inner
 content of the policy, which will be the plain text policy.
 
 The ``active`` file is used to set a policy as the currently active policy.
@@ -238,44 +242,42 @@ Since only a single policy can be active at one time, all other policies
 will be marked inactive. The policy being marked active must have a policy
 version greater or equal to the currently-running version.
 
-The ``update`` file is used to update a policy that is already present in
-the kernel. This file is write-only and accepts a PKCS#7 signed policy.
-One check will always be performed on this policy: the policy_names must
-match with the updated version and the existing version. One additional check
-may be made: If the policy being updated is the active policy, the updated
-policy must have a policy version greater than or equal to the currently-running
-version; This is to prevent rollback attacks.
+The ``update`` file is used to update a policy that is already present
+in the kernel. This file is write-only and accepts a PKCS#7 signed
+policy. One check will always be performed on this policy: the
+``policy_names`` must match with the updated version and the existing
+version. There is also an additional check: if the policy being updated
+is the active policy, the updated policy must have a policy version
+greater than or equal to the currently-running version. This is to
+prevent rollback attacks.
 
 The ``delete`` file is used to remove a policy that is no longer needed.
 This file is write-only and accepts a value of ``1`` to delete the policy.
 On deletion, the securityfs node representing the policy will be removed.
 The policy that is currently active cannot be deleted.
 
-Similarly, the writes to both ``update`` and ``new_policy`` above will
-result in an error upon syntactically invalid or untrusted policies.
-In the case of ``new_policy``, it will also error if a policy already
-exists with the same ``policy_name``.
+Similarly, writing to both ``update`` and ``new_policy`` results in
+syntax or untrusted policy error. In the case of the latter, it will
+also error out if a policy already exists with the same ``policy_name``.
 
 Deploying these policies will *not* cause IPE to start enforcing this
-policy. Once deployment is successful, a policy can be marked as active,
-via ``/sys/kernel/security/ipe/$policy_name/active``. IPE will enforce
-whatever policy is marked as active. For our example, we can activate
-the ``Ex_Policy`` via::
+policy. Once deployment is successful, a policy can be activated, by
+``/sys/kernel/security/ipe/$policy_name/active``. IPE will enforce
+active policies. For example, the ``Ex_Policy`` can be activated by::
 
    echo 1 > "/sys/kernel/security/ipe/Ex_Policy/active"
 
-At which point, ``Ex_Policy`` will now be the enforced policy on the
+From above point on, ``Ex_Policy`` is now the enforced policy on the
 system.
 
 IPE also provides a way to delete policies. This can be done via the
 ``delete`` securityfs node, ``/sys/kernel/security/ipe/$policy_name/delete``.
-Writing ``1`` to that file will delete that node::
+Writing ``1`` to that file deletes the policy::
 
    echo 1 > "/sys/kernel/security/ipe/$policy_name/delete"
 
-There is only one requirement to delete a policy:
-
-1. The policy being deleted must not be the active policy.
+There is only one requirement to delete a policy: the policy being deleted
+must be inactive.
 
 .. NOTE::
 
@@ -286,9 +288,9 @@ Modes
 ~~~~~
 
 IPE supports two modes of operation: permissive (similar to SELinux's
-permissive mode) and enforce. Permissive mode performs the same checks
-as enforce mode, and logs policy violations, but will not enforce the
-policy. This allows users to test policies before enforcing them.
+permissive mode) and enforced. In permissive mode, all events are
+checked and policy violations are logged, but the policy is not really
+enforced. This allows users to test policies before enforcing them.
 
 The default mode is enforce, and can be changed via the kernel command
 line parameter ``ipe.enforce=(0|1)``, or the securityfs node
@@ -314,11 +316,12 @@ Event Examples::
    type=1300 audit(1653364735.161:64): arch=c000003e syscall=9 success=no exit=-13 a0=0 a1=1000 a2=4 a3=20 items=0 ppid=455 pid=774 auid=0 uid=0 gid=0 euid=0 suid=0 fsuid=0 egid=0 sgid=0 fsgid=0 tty=ttyS0 ses=3 comm="mmap" exe="/root/host/mmap" subj=kernel key=(null)
    type=1327 audit(1653364735.161:64): proctitle=686F73742F6D6D617000410058⏎
 
-This event indicates that IPE made an access control decision; the IPE specific
-record (1420) will always be emitted in conjunction with a ``AUDITSYSCALL`` record.
+This event indicates that IPE made an access control decision; the IPE
+specific record (1420) is always emitted in conjunction with a
+``AUDITSYSCALL`` record.
 
-Determining whether IPE is in permissive can be derived from the success and exit
-field of the AUDITSYSCALL record
+Determining whether IPE is in permissive or enforced mode can be derived
+from ``success`` property and exit code of the ``AUDITSYSCALL`` record.
 
 
 
@@ -327,13 +330,13 @@ Field descriptions:
 +---------------+------------+-----------+-------------------------------------------------------------------------+
 | Field         | Value Type | Optional? | Description of Value                                                    |
 +===============+============+===========+=========================================================================+
-| path          | string     | Yes       | The absolute path to the file that was the subject of the evaluation    |
+| path          | string     | Yes       | The absolute path to the evaluated file                                 |
 +---------------+------------+-----------+-------------------------------------------------------------------------+
-| ino           | integer    | Yes       | The inode number of the file that was the subject of the evaluation     |
+| ino           | integer    | Yes       | The inode number of the evaluated file                                  |
 +---------------+------------+-----------+-------------------------------------------------------------------------+
-| dev           | string     | Yes       | The device name that the file under evaluation belongs to, e.g. vda     |
+| dev           | string     | Yes       | The device name of the evaluated file, e.g. vda                         |
 +---------------+------------+-----------+-------------------------------------------------------------------------+
-| rule          | string     | No        | The exact rule in IPE's policy that the evaluation matched              |
+| rule          | string     | No        | The matched policy rule                                                 |
 +---------------+------------+-----------+-------------------------------------------------------------------------+
 
 1403 AUDIT_MAC_POLICY_LOAD
@@ -350,11 +353,11 @@ This record will always be emitted in conjunction with a ``AUDITSYSCALL`` record
 +----------------+------------+-----------+--------------------------------------------------------------+
 | Field          | Value Type | Optional? | Description of Value                                         |
 +================+============+===========+==============================================================+
-| policy_name    | string     | No        | The policy_name field of the policy.                         |
+| policy_name    | string     | No        | The policy name                                              |
 +----------------+------------+-----------+--------------------------------------------------------------+
-| policy_version | string     | No        | The policy_version field of the policy                       |
+| policy_version | string     | No        | The policy version                                           |
 +----------------+------------+-----------+--------------------------------------------------------------+
-| sha256         | string     | Yes*      | A flat hash of the policy. Can be used to identify a policy. |
+| sha256         | string     | Yes*      | The policy hash                                              |
 +----------------+------------+-----------+--------------------------------------------------------------+
 | auid           | integer    | No        | The audit user ID.                                           |
 +----------------+------------+-----------+--------------------------------------------------------------+
@@ -379,17 +382,17 @@ This record will always be emitted in conjunction with a ``AUDITSYSCALL`` record
 +------------------------+------------+-----------+----------------------------------------------------+
 | Field                  | Value Type | Optional? | Description of Value                               |
 +========================+============+===========+====================================================+
-| old_active_pol_name    | string     | No        | The policy_name field of the old active policy.    |
+| old_active_pol_name    | string     | No        | The name of previous active policy                 |
 +------------------------+------------+-----------+----------------------------------------------------+
-| old_active_pol_version | string     | No        | The policy_version field of the old active policy. |
+| old_active_pol_version | string     | No        | The version of previous active policy              |
 +------------------------+------------+-----------+----------------------------------------------------+
-| old_sha256             | string     | Yes*      | A flat hash of the old active policy.              |
+| old_sha256             | string     | Yes*      | The hash of previous active policy                 |
 +------------------------+------------+-----------+----------------------------------------------------+
-| new_active_pol_name    | string     | No        | The policy_name field of the new active policy.    |
+| new_active_pol_name    | string     | No        | The name of current active policy                  |
 +------------------------+------------+-----------+----------------------------------------------------+
-| new_active_pol_version | string     | No        | The policy_version field of the new active policy. |
+| new_active_pol_version | string     | No        | The version of current active policy               |
 +------------------------+------------+-----------+----------------------------------------------------+
-| new_sha256             | string     | Yes*      | A flat hash of the new active policy.              |
+| new_sha256             | string     | Yes*      | The hash of current active policy                  |
 +------------------------+------------+-----------+----------------------------------------------------+
 | auid                   | integer    | No        | The audit user ID.                                 |
 +------------------------+------------+-----------+----------------------------------------------------+
@@ -415,19 +418,19 @@ Event Examples::
 
 This record will always be emitted in conjunction with a ``AUDITSYSCALL`` record for the ``write`` syscall.
 
-+------------+------------+-----------+-------------------------------------------------------------------+
-| Field      | Value Type | Optional? | Description of Value                                              |
-+============+============+===========+===================================================================+
-| permissive | integer    | No        | The state IPE is being switched to. 1 is permissive, 0 is enforce |
-+------------+------------+-----------+-------------------------------------------------------------------+
-| auid       | integer    | No        | The audit user ID.                                                |
-+------------+------------+-----------+-------------------------------------------------------------------+
-| ses        | integer    | No        | The session ID.                                                   |
-+------------+------------+-----------+-------------------------------------------------------------------+
-| lsm        | string     | No        | The lsm name associated with the event.                           |
-+------------+------------+-----------+-------------------------------------------------------------------+
-| res        | integer    | No        | The operation result.                                             |
-+------------+------------+-----------+-------------------------------------------------------------------+
++------------+------------+-----------+-------------------------------------------------------------------------------------+
+| Field      | Value Type | Optional? | Description of Value                                                                |
++============+============+===========+=====================================================================================+
+| permissive | integer    | No        | The state IPE is being switched to. 1 is in permissive mode; 0 is in enforced mode. |
++------------+------------+-----------+-------------------------------------------------------------------------------------+
+| auid       | integer    | No        | The audit user ID.                                                                  |
++------------+------------+-----------+-------------------------------------------------------------------------------------+
+| ses        | integer    | No        | The session ID.                                                                     |
++------------+------------+-----------+-------------------------------------------------------------------------------------+
+| lsm        | string     | No        | The lsm name associated with the event.                                             |
++------------+------------+-----------+-------------------------------------------------------------------------------------+
+| res        | integer    | No        | The operation result.                                                               |
++------------+------------+-----------+-------------------------------------------------------------------------------------+
 
 Success Auditing
 ^^^^^^^^^^^^^^^^
@@ -435,8 +438,8 @@ Success Auditing
 IPE supports success auditing. When enabled, all events that pass IPE
 policy and are not blocked will emit an audit event. This is disabled by
 default, and can be enabled via the kernel command line
-``ipe.success_audit=(0|1)`` or the securityfs node,
-``/sys/kernel/security/ipe/success_audit``.
+``ipe.success_audit=(0|1)`` or
+``/sys/kernel/security/ipe/success_audit`` securityfs file.
 
 This is *very* noisy, as IPE will check every userspace binary on the
 system, but is useful for debugging policies.
@@ -538,9 +541,9 @@ dmverity_roothash
 
    This property can be utilized for authorization or revocation of
    specific dm-verity volumes, identified via root hash. It has a
-   dependency on the DM_VERITY module. This property is controlled by the
-   Kconfig ``CONFIG_IPE_PROP_DM_VERITY``. The format of this property
-   is::
+   dependency on the DM_VERITY module. This property is controlled by
+   the ``CONFIG_IPE_PROP_DM_VERITY`` config option. The format of this
+   property is::
 
       dmverity_roothash=DigestName:HexadecimalString
 
@@ -564,11 +567,11 @@ dmverity_roothash
 dmverity_signature
 ~~~~~~~~~~~~~~~~~~
 
-   This property can be utilized for authorization of all dm-verity volumes
-   that have a signed roothash that chains to a keyring specified by dm-verity's
-   configuration, either the system trusted keyring, or the secondary keyring.
-   It has an additional dependency on the ``DM_VERITY_VERIFY_ROOTHASH_SIG``
-   Kconfig. This property is controlled by the Kconfig
+   This property can be utilized for authorization of all dm-verity
+   volumes that have a signed roothash that chains to a keyring
+   specified by dm-verity's configuration, either the system trusted
+   keyring, or the secondary keyring. It depends on
+   ``DM_VERITY_VERIFY_ROOTHASH_SIG`` config option and is controlled by
    ``CONFIG_IPE_PROP_DM_VERITY``. The format of this property is::
 
       dmverity_signature=(TRUE|FALSE)
@@ -578,9 +581,8 @@ fsverity_digest
 
    This property can be utilized for authorization or revocation of
    specific fsverity enabled file, identified via its fsverity digest.
-   It has a dependency on the FS_VERITY module. This property is
-   controlled by the Kconfig ``CONFIG_IPE_PROP_FS_VERITY``.
-   The format of this property is::
+   It depends on ``FS_VERITY`` config option and is controlled by
+   ``CONFIG_IPE_PROP_FS_VERITY``. The format of this property is::
 
       fsverity_digest=DigestName:HexadecimalString
 
@@ -594,12 +596,13 @@ fsverity_signature
 
 Version 1
 
-   This property can be utilized for authorization of all fsverity enabled
-   files that is verified by fsverity. The keyring that the signature is
-   verified against is subject to fsverity's configuration, typically the fsverity
-   keyring. It has a dependency on the ``CONFIG_FS_VERITY_BUILTIN_SIGNATURES``
-   Kconfig. This property is controlled by the Kconfig
-   ``CONFIG_IPE_PROP_FS_VERITY``. The format of this property is::
+   This property can be utilized for authorization of all fsverity
+   enabled files that is verified by fsverity. The keyring that the
+   signature is verified against is subject to fsverity's configuration,
+   typically the fsverity keyring. It depends on
+   ``CONFIG_FS_VERITY_BUILTIN_SIGNATURES`` is controlled controlled by
+   the Kconfig ``CONFIG_IPE_PROP_FS_VERITY``. The format of this
+   property is::
 
       fsverity_signature=(TRUE|FALSE)
 
@@ -704,7 +707,7 @@ A:
    Loadpin and IPE differ fairly dramatically, as Loadpin controls only the IPE
    equivalent of ``KERNEL_READ``, whereas IPE is capable of controlling execution,
    on top of ``KERNEL_READ``. The trust model is also different; Loadpin roots its
-   trust in the initial super-block, instead, IPE roots its trust in the kernel
+   trust in the initial super-block, whereas trust in IPE is stemmed from kernel
    itself (via ``SYSTEM_TRUSTED_KEYS``).
 
 -----------

Thanks.

Fan Wu Feb. 2, 2023, 12:19 a.m. UTC | #2

On Tue, Jan 31, 2023 at 10:59:59AM +0700, Bagas Sanjaya wrote:
> On Mon, Jan 30, 2023 at 02:57:31PM -0800, Fan Wu wrote:
> 
> What about wordings below instead?

Thanks for the review!
>  
> -IPE policy supports comments. The character '#' will function as a
> -comment, ignoring all characters to the right of '#' until the newline.
> +IPE policy supports comments. Any line which is prefixed with ``#`` will
> +be ignored.
This one is actually incorrect. The '#' can also appear at the end of a rule.
So it is not only prefixed to a line.

Other than this part, everything looks great, I will take them in the next
version.

-Fan

>  
>  -----------
> 
> Thanks.
> 
> -- 
> An old man doll... just what I always wanted! - Clara

Patch

diff --git a/Documentation/admin-guide/LSM/index.rst b/Documentation/admin-guide/LSM/index.rst
index a6ba95fbaa9f..ce63be6d64ad 100644
--- a/Documentation/admin-guide/LSM/index.rst
+++ b/Documentation/admin-guide/LSM/index.rst
@@ -47,3 +47,4 @@  subdirectories.
    tomoyo
    Yama
    SafeSetID
+   ipe
diff --git a/Documentation/admin-guide/LSM/ipe.rst b/Documentation/admin-guide/LSM/ipe.rst
new file mode 100644
index 000000000000..b676cea62b2e
--- /dev/null
+++ b/Documentation/admin-guide/LSM/ipe.rst
@@ -0,0 +1,729 @@ 
+.. SPDX-License-Identifier: GPL-2.0
+
+Integrity Policy Enforcement (IPE)
+==================================
+
+.. NOTE::
+
+   This is the documentation for admins, system builders, or individuals
+   attempting to use IPE. If you're looking for more developer-focused
+   documentation about IPE please see `Documentation/security/ipe.rst`
+
+Overview
+--------
+
+IPE is a Linux Security Module which takes a complimentary approach to
+access control. Whereas existing mandatory access control mechanisms
+base their decisions on labels and paths, IPE instead determines
+whether or not an operation should be allowed based on immutable
+security properties of the system component the operation is being
+performed on.
+
+IPE itself does not mandate how the security property should be
+evaluated, but relies on an extensible set of external property providers
+to evaluate the component. IPE makes its decision based on reference
+values for the selected properties, specified in the IPE policy.
+
+The reference values represent the value that the policy writer and the
+local system administrator (based on the policy signature) trust for the
+system to accomplish the desired tasks.
+
+One such provider is for example dm-verity, which is able to represent
+the integrity property of a partition (its immutable state) with a digest.
+
+IPE is compiled under ``CONFIG_SECURITY_IPE`` (Security -> Integrity Policy Enforcement (IPE)).
+
+Use Cases
+---------
+
+IPE works best in fixed-function devices: devices in which their purpose
+is clearly defined and not supposed to be changed (e.g. network firewall
+device in a data center, an IoT device, etcetera), where all software and
+configuration is built and provisioned by the system owner.
+
+IPE is a long-way off for use in general-purpose computing: the Linux
+community as a whole tends to follow a decentralized trust model,
+known as the web of trust, which IPE has no support for as of yet.
+
+IPE, instead of supporting web of trust, supports PKI, which generally
+designates a set of entities that provide a measure of absolute trust.
+
+Additionally, while most packages are signed today, the files inside
+the packages (for instance, the executables), tend to be unsigned. This
+makes it difficult to utilize IPE in systems where a package manager is
+expected to be functional, without major changes to the package manager
+and ecosystem behind it.
+
+DIGLIM [#diglim]_ is a system that when combined with IPE, could be used to
+enable general purpose computing scenarios.
+
+Known Gaps
+----------
+
+IPE cannot verify the integrity of anonymous executable memory, such as
+the trampolines created by gcc closures and libffi (<3.4.2), or JIT'd code.
+Unfortunately, as this is dynamically generated code, there is no way
+for IPE to ensure the integrity of this code to form a trust basis. In all
+cases, the return result for these operations will be whatever the admin
+configures as the ``DEFAULT`` action for ``EXECUTE``.
+
+IPE cannot verify the integrity of interpreted languages' programs when
+these scripts are invoked via ``<interpreter> <file>``. This is because
+the way interpreters execute these files, the scripts themselves are not
+evaluated as executable code through one of IPE's hooks, as they are merely
+files that are read (as opposed to executable code) [#interpreters]_.
+
+Threat Model
+------------
+
+The threat type addressed by IPE is tampering of executable userspace
+code beyond the initially booted kernel, and the initial verification of
+kernel modules that are loaded in userspace through ``modprobe`` or
+``insmod``.
+
+A bare-minimum example of a threat that should be mitigated by IPE, is
+a hostile binary is downloaded with all required binaries (including
+a loader, libc, etc). With IPE, this hostile binary should not able to
+be executed, nor any of the downloaded binaries.
+
+Tampering violates integrity, and being unable to verify the integrity,
+results in a lack of trust. IPE's role in mitigating this threat is to
+verify the integrity (and authenticity) of all executable code and to
+deny their use if they cannot be trusted (as integrity verification fails,
+or the authorization check fails against the reference value in the policy).
+IPE generates audit logs which may be utilized to detect failures resulting
+from failure to pass policy.
+
+Tampering threat scenarios include modification or replacement of
+executable code by a range of actors including:
+
+-  Actors with physical access to the hardware
+-  Actors with local network access to the system
+-  Actors with access to the deployment system
+-  Compromised internal systems under external control
+-  Malicious end users of the system
+-  Compromised end users of the system
+-  Remote (external) compromise of the system
+
+IPE does not mitigate threats arising from malicious authorized
+developers (with access to a signing certificate), or compromised
+developer tools used by authorized developers (i.e. Return Oriented
+Programming attacks). Additionally, IPE draws hard security boundary
+between userspace and kernelspace. As a result, IPE does not provide
+any protections against a kernel level exploit, and a kernel-level
+exploit can disable or tamper with IPE's protections.
+
+Policy
+------
+
+IPE policy is a plain-text [#devdoc]_ policy composed of multiple statements
+over several lines. There is one required line, at the top of the
+policy, indicating the policy name, and the policy version, for
+instance::
+
+   policy_name=Ex_Policy policy_version=0.0.0
+
+The policy name is a unique key identifying this policy in a human
+readable name. This is used to create nodes under securityfs as well as
+uniquely identify policies to deploy new policies vs update existing
+policies.
+
+The policy version indicates the current version of the policy (NOT the
+policy syntax version). This is used to prevent rollback of policy to
+potentially insecure previous versions of the policy.
+
+The next portion of IPE policy are rules. Rules are formed by key=value
+pairs, known as properties. IPE rules require two properties: "action",
+which determines what IPE does when it encounters a match against the
+rule, and "op", which determines when that rule should be evaluated.
+The ordering is significant, a rule must start with "op", and end with
+"action". Thus, a minimal rule is::
+
+   op=EXECUTE action=ALLOW
+
+This example will allow any execution. Additional properties are used to
+restrict attributes about the files being evaluated. These properties
+are intended to be descriptions of systems within the kernel that can
+provide a measure of integrity verification, such that IPE can determine
+the trust of the resource based on the "value" half of the property.
+
+Rules are evaluated top-to-bottom. As a result, any revocation rules,
+or denies should be placed early in the file to ensure that these rules
+are evaluated before a rule with "action=ALLOW" is hit.
+
+IPE policy supports comments. The character '#' will function as a
+comment, ignoring all characters to the right of '#' until the newline.
+
+The default behavior of IPE evaluations can also be expressed in policy,
+through the ``DEFAULT`` statement. This can be done at a global level,
+or a per-operation level::
+
+   # Global
+   DEFAULT action=ALLOW
+
+   # Operation Specific
+   DEFAULT op=EXECUTE action=ALLOW
+
+A default must be set for all known operations in IPE. If you want to
+preserve older policies being compatible with newer kernels that can introduce
+new operations, please set a global default of 'ALLOW', and override the
+defaults on a per-operation basis.
+
+With configurable policy-based LSMs, there's several issues with
+enforcing the configurable policies at startup, around reading and
+parsing the policy:
+
+1. The kernel *should* not read files from userspace, so directly reading
+   the policy file is prohibited.
+2. The kernel command line has a character limit, and one kernel module
+   should not reserve the entire character limit for its own
+   configuration.
+3. There are various boot loaders in the kernel ecosystem, so handing
+   off a memory block would be costly to maintain.
+
+As a result, IPE has addressed this problem through a concept of a "boot
+policy". A boot policy is a minimal policy, compiled into the kernel.
+This policy is intended to get the system to a state where userspace is
+set up and ready to receive commands, at which point a more complex
+policy can be deployed via securityfs. The boot policy can be specified
+via the Kconfig, ``SECURITY_IPE_BOOT_POLICY``, which accepts a path to
+a plain-text version of the IPE policy to apply. This policy will be
+compiled into the kernel. If not specified, IPE will be disabled until
+a policy is deployed and activated through securityfs.
+
+Deploying Policies
+~~~~~~~~~~~~~~~~~~
+
+Policies can be deployed from userspace through securityfs. These policies
+are signed through the PKCS#7 message format to enforce some level of
+authorization of the policies (prohibiting an attacker from gaining
+unconstrained root, and deploying an "allow all" policy). These
+policies must be signed by a certificate that chains to the
+``SYSTEM_TRUSTED_KEYRING``. Through openssl, the signing can be done via::
+
+   openssl smime -sign \
+      -in "$MY_POLICY" \
+      -signer "$MY_CERTIFICATE" \
+      -inkey "$MY_PRIVATE_KEY" \
+      -noattr \
+      -nodetach \
+      -nosmimecap \
+      -outform der \
+      -out "$MY_POLICY.p7b"
+
+Deploying the policies is done through securityfs, through the
+``new_policy`` node. To deploy a policy, simply cat the file into the
+securityfs node::
+
+   cat "$MY_POLICY.p7b" > /sys/kernel/security/ipe/new_policy
+
+Upon success, this will create one subdirectory under
+``/sys/kernel/security/ipe/policies/``. The subdirectory will be the
+``policy_name`` field of the policy deployed, so for the example above,
+the directory will be ``/sys/kernel/security/ipe/policies/Ex_Policy``.
+Within this directory, there will be five files: ``pkcs7``, ``policy``,
+``active``, ``update``, and ``delete``.
+
+The ``pkcs7`` file is read only. Reading will provide the raw PKCS#7 data
+that was provided to the kernel, representing the policy. Writing, will
+deploy an in-place policy update.If the policy being read is the boot
+policy, when read, this will return ENOENT, as this policy is not signed.
+
+The ``policy`` file is read only. Reading will provide the PKCS#7 inner
+content of the policy, which will be the plain text policy.
+
+The ``active`` file is used to set a policy as the currently active policy.
+This file is rw, and accepts a value of ``"1"`` to set the policy as active.
+Since only a single policy can be active at one time, all other policies
+will be marked inactive. The policy being marked active must have a policy
+version greater or equal to the currently-running version.
+
+The ``update`` file is used to update a policy that is already present in
+the kernel. This file is write-only and accepts a PKCS#7 signed policy.
+One check will always be performed on this policy: the policy_names must
+match with the updated version and the existing version. One additional check
+may be made: If the policy being updated is the active policy, the updated
+policy must have a policy version greater than or equal to the currently-running
+version; This is to prevent rollback attacks.
+
+The ``delete`` file is used to remove a policy that is no longer needed.
+This file is write-only and accepts a value of ``1`` to delete the policy.
+On deletion, the securityfs node representing the policy will be removed.
+The policy that is currently active cannot be deleted.
+
+Similarly, the writes to both ``update`` and ``new_policy`` above will
+result in an error upon syntactically invalid or untrusted policies.
+In the case of ``new_policy``, it will also error if a policy already
+exists with the same ``policy_name``.
+
+Deploying these policies will *not* cause IPE to start enforcing this
+policy. Once deployment is successful, a policy can be marked as active,
+via ``/sys/kernel/security/ipe/$policy_name/active``. IPE will enforce
+whatever policy is marked as active. For our example, we can activate
+the ``Ex_Policy`` via::
+
+   echo 1 > "/sys/kernel/security/ipe/Ex_Policy/active"
+
+At which point, ``Ex_Policy`` will now be the enforced policy on the
+system.
+
+IPE also provides a way to delete policies. This can be done via the
+``delete`` securityfs node, ``/sys/kernel/security/ipe/$policy_name/delete``.
+Writing ``1`` to that file will delete that node::
+
+   echo 1 > "/sys/kernel/security/ipe/$policy_name/delete"
+
+There is only one requirement to delete a policy:
+
+1. The policy being deleted must not be the active policy.
+
+.. NOTE::
+
+   If a traditional MAC system is enabled (SELinux, apparmor, smack), all
+   writes to ipe's securityfs nodes require ``CAP_MAC_ADMIN``.
+
+Modes
+~~~~~
+
+IPE supports two modes of operation: permissive (similar to SELinux's
+permissive mode) and enforce. Permissive mode performs the same checks
+as enforce mode, and logs policy violations, but will not enforce the
+policy. This allows users to test policies before enforcing them.
+
+The default mode is enforce, and can be changed via the kernel command
+line parameter ``ipe.enforce=(0|1)``, or the securityfs node
+``/sys/kernel/security/ipe/enforce``.
+
+.. NOTE::
+
+   If a traditional MAC system is enabled (SELinux, apparmor, smack, etcetera),
+   all writes to ipe's securityfs nodes require ``CAP_MAC_ADMIN``.
+
+Audit Events
+~~~~~~~~~~~~
+
+1420 AUDIT_IPE_ACCESS
+^^^^^^^^^^^^^^^^^^^^^
+Event Examples::
+
+   type=1420 audit(1653364370.067:61): path="/root/fs/rw/plain/execve" dev="vdc1" ino=16 rule="DEFAULT op=EXECUTE action=DENY"
+   type=1300 audit(1653364370.067:61): arch=c000003e syscall=10 success=no exit=-13 a0=7f0bf0644000 a1=4f80 a2=5 a3=7f0bf043d300 items=0 ppid=455 pid=737 auid=0 uid=0 gid=0 euid=0 suid=0 fsuid=0 egid=0 sgid=0 fsgid=0 tty=ttyS0 ses=3 comm="mprotect" exe="/root/host/mprotect" subj=kernel key=(null)
+   type=1327 audit(1653364370.067:61): proctitle=686F73742F6D70726F7465637400534800527C5700527C5800706C61696E2F657865637665
+
+   type=1420 audit(1653364735.161:64): rule="DEFAULT op=EXECUTE action=DENY"
+   type=1300 audit(1653364735.161:64): arch=c000003e syscall=9 success=no exit=-13 a0=0 a1=1000 a2=4 a3=20 items=0 ppid=455 pid=774 auid=0 uid=0 gid=0 euid=0 suid=0 fsuid=0 egid=0 sgid=0 fsgid=0 tty=ttyS0 ses=3 comm="mmap" exe="/root/host/mmap" subj=kernel key=(null)
+   type=1327 audit(1653364735.161:64): proctitle=686F73742F6D6D617000410058⏎
+
+This event indicates that IPE made an access control decision; the IPE specific
+record (1420) will always be emitted in conjunction with a ``AUDITSYSCALL`` record.
+
+Determining whether IPE is in permissive can be derived from the success and exit
+field of the AUDITSYSCALL record
+
+
+
+Field descriptions:
+
++---------------+------------+-----------+-------------------------------------------------------------------------+
+| Field         | Value Type | Optional? | Description of Value                                                    |
++===============+============+===========+=========================================================================+
+| path          | string     | Yes       | The absolute path to the file that was the subject of the evaluation    |
++---------------+------------+-----------+-------------------------------------------------------------------------+
+| ino           | integer    | Yes       | The inode number of the file that was the subject of the evaluation     |
++---------------+------------+-----------+-------------------------------------------------------------------------+
+| dev           | string     | Yes       | The device name that the file under evaluation belongs to, e.g. vda     |
++---------------+------------+-----------+-------------------------------------------------------------------------+
+| rule          | string     | No        | The exact rule in IPE's policy that the evaluation matched              |
++---------------+------------+-----------+-------------------------------------------------------------------------+
+
+1403 AUDIT_MAC_POLICY_LOAD
+^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+Event Example::
+
+   type=1403 audit(1653425529.927:53): policy_name="dmverity_roothash" policy_version=0.0.0 sha256=DC67AC19E05894EFB3170A8E55DE529794E248C2 auid=4294967295 ses=4294967295 lsm=ipe res=1
+   type=1300 audit(1653425529.927:53): arch=c000003e syscall=1 success=yes exit=2567 a0=3 a1=5596fcae1fb0 a2=a07 a3=2 items=0 ppid=184 pid=229 auid=4294967295 uid=0 gid=0 euid=0 suid=0 fsuid=0 egid=0 sgid=0 fsgid=0 tty=pts0 ses=4294967295 comm="python3" exe="/usr/bin/python3.10" key=(null)
+   type=1327 audit(1653425529.927:53): PROCTITLE proctitle=707974686F6E3300746573742F6D61696E2E7079002D66002E2E
+
+This record will always be emitted in conjunction with a ``AUDITSYSCALL`` record for the ``write`` syscall.
+
++----------------+------------+-----------+--------------------------------------------------------------+
+| Field          | Value Type | Optional? | Description of Value                                         |
++================+============+===========+==============================================================+
+| policy_name    | string     | No        | The policy_name field of the policy.                         |
++----------------+------------+-----------+--------------------------------------------------------------+
+| policy_version | string     | No        | The policy_version field of the policy                       |
++----------------+------------+-----------+--------------------------------------------------------------+
+| sha256         | string     | Yes*      | A flat hash of the policy. Can be used to identify a policy. |
++----------------+------------+-----------+--------------------------------------------------------------+
+| auid           | integer    | No        | The audit user ID.                                           |
++----------------+------------+-----------+--------------------------------------------------------------+
+| ses            | integer    | No        | The session ID.                                              |
++----------------+------------+-----------+--------------------------------------------------------------+
+| lsm            | string     | No        | The lsm name associated with the event.                      |
++----------------+------------+-----------+--------------------------------------------------------------+
+| res            | integer    | No        | The operation result.                                        |
++----------------+------------+-----------+--------------------------------------------------------------+
+
+1405 AUDIT_MAC_CONFIG_CHANGE
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+Event Example::
+
+   type=1405 audit(1653425583.136:54): old_active_pol_name="Allow_All" old_active_pol_version=0.0.0 old_sha256=DA39A3EE5E6B4B0D3255BFEF95601890AFD80709 new_active_pol_name="dmverity_roothash" new_active_pol_version=0.0.0 new_sha256=DC67AC19E05894EFB3170A8E55DE529794E248C2 auid=4294967295 ses=4294967295 lsm=ipe res=1
+   type=1300 audit(1653425583.136:54): SYSCALL arch=c000003e syscall=1 success=yes exit=2 a0=3 a1=5596fcae1fb0 a2=2 a3=2 items=0 ppid=184 pid=229 auid=4294967295 uid=0 gid=0 euid=0 suid=0 fsuid=0 egid=0 sgid=0 fsgid=0 tty=pts0 ses=4294967295 comm="python3" exe="/usr/bin/python3.10" key=(null)
+   type=1327 audit(1653425583.136:54): PROCTITLE proctitle=707974686F6E3300746573742F6D61696E2E7079002D66002E2
+
+This record will always be emitted in conjunction with a ``AUDITSYSCALL`` record for the ``write`` syscall.
+
++------------------------+------------+-----------+----------------------------------------------------+
+| Field                  | Value Type | Optional? | Description of Value                               |
++========================+============+===========+====================================================+
+| old_active_pol_name    | string     | No        | The policy_name field of the old active policy.    |
++------------------------+------------+-----------+----------------------------------------------------+
+| old_active_pol_version | string     | No        | The policy_version field of the old active policy. |
++------------------------+------------+-----------+----------------------------------------------------+
+| old_sha256             | string     | Yes*      | A flat hash of the old active policy.              |
++------------------------+------------+-----------+----------------------------------------------------+
+| new_active_pol_name    | string     | No        | The policy_name field of the new active policy.    |
++------------------------+------------+-----------+----------------------------------------------------+
+| new_active_pol_version | string     | No        | The policy_version field of the new active policy. |
++------------------------+------------+-----------+----------------------------------------------------+
+| new_sha256             | string     | Yes*      | A flat hash of the new active policy.              |
++------------------------+------------+-----------+----------------------------------------------------+
+| auid                   | integer    | No        | The audit user ID.                                 |
++------------------------+------------+-----------+----------------------------------------------------+
+| ses                    | integer    | No        | The session ID.                                    |
++------------------------+------------+-----------+----------------------------------------------------+
+| lsm                    | string     | No        | The lsm name associated with the event.            |
++------------------------+------------+-----------+----------------------------------------------------+
+| res                    | integer    | No        | The operation result.                              |
++------------------------+------------+-----------+----------------------------------------------------+
+
+1404 AUDIT_MAC_STATUS
+^^^^^^^^^^^^^^^^^^^^^
+
+Event Examples::
+
+   type=1404 audit(1653425689.008:55): permissive=1 auid=0 ses=4294967295 lsm=ipe res=1
+   type=1300 audit(1653425689.008:55): arch=c000003e syscall=1 success=yes exit=2 a0=1 a1=55c1065e5c60 a2=2 a3=0 items=0 ppid=405 pid=441 auid=0 uid=0 gid=0 euid=0 suid=0 fsuid=0 egid=0 sgid=)
+   type=1327 audit(1653425689.008:55): proctitle="-bash"
+
+   type=1404 audit(1653425689.008:55): permissive=0 auid=0 ses=4294967295 lsm=ipe res=1
+   type=1300 audit(1653425689.008:55): arch=c000003e syscall=1 success=yes exit=2 a0=1 a1=55c1065e5c60 a2=2 a3=0 items=0 ppid=405 pid=441 auid=0 uid=0 gid=0 euid=0 suid=0 fsuid=0 egid=0 sgid=)
+   type=1327 audit(1653425689.008:55): proctitle="-bash"
+
+This record will always be emitted in conjunction with a ``AUDITSYSCALL`` record for the ``write`` syscall.
+
++------------+------------+-----------+-------------------------------------------------------------------+
+| Field      | Value Type | Optional? | Description of Value                                              |
++============+============+===========+===================================================================+
+| permissive | integer    | No        | The state IPE is being switched to. 1 is permissive, 0 is enforce |
++------------+------------+-----------+-------------------------------------------------------------------+
+| auid       | integer    | No        | The audit user ID.                                                |
++------------+------------+-----------+-------------------------------------------------------------------+
+| ses        | integer    | No        | The session ID.                                                   |
++------------+------------+-----------+-------------------------------------------------------------------+
+| lsm        | string     | No        | The lsm name associated with the event.                           |
++------------+------------+-----------+-------------------------------------------------------------------+
+| res        | integer    | No        | The operation result.                                             |
++------------+------------+-----------+-------------------------------------------------------------------+
+
+Success Auditing
+^^^^^^^^^^^^^^^^
+
+IPE supports success auditing. When enabled, all events that pass IPE
+policy and are not blocked will emit an audit event. This is disabled by
+default, and can be enabled via the kernel command line
+``ipe.success_audit=(0|1)`` or the securityfs node,
+``/sys/kernel/security/ipe/success_audit``.
+
+This is *very* noisy, as IPE will check every userspace binary on the
+system, but is useful for debugging policies.
+
+.. NOTE::
+
+   If a traditional MAC system is enabled (SELinux, apparmor, smack, etcetera),
+   all writes to ipe's securityfs nodes require ``CAP_MAC_ADMIN``.
+
+Properties
+----------
+
+As explained above, IPE properties are ``key=value`` pairs expressed in
+IPE policy. Two properties are built-into the policy parser: 'op' and
+'action'. The other properties are determinstic attributes to express
+across files. Currently those properties are: '``boot_verified``',
+'``dmverity_signature``', '``dmverity_roothash``', '``fsverity_signature``',
+'``fsverity_digest``'. A description of all properties supported by IPE
+are listed below:
+
+op
+~~
+
+Indicates the operation for a rule to apply to. Must be in every rule,
+as the first token. IPE supports the following operations:
+
+   ``EXECUTE``
+
+      Pertains to any file attempting to be executed, or loaded as an
+      executable.
+
+   ``FIRMWARE``:
+
+      Pertains to firmware being loaded via the firmware_class interface.
+      This covers both the preallocated buffer and the firmware file
+      itself.
+
+   ``KMODULE``:
+
+      Pertains to loading kernel modules via ``modprobe`` or ``insmod``.
+
+   ``KEXEC_IMAGE``:
+
+      Pertains to kernel images loading via ``kexec``.
+
+   ``KEXEC_INITRAMFS``
+
+      Pertains to initrd images loading via ``kexec --initrd``.
+
+   ``POLICY``:
+
+      Controls loading polcies via reading a kernel-space initiated read.
+
+      An example of such is loading IMA policies by writing the path
+      to the policy file to ``$securityfs/ima/policy``
+
+   ``X509_CERT``:
+
+      Controls loading IMA certificates through the Kconfigs,
+      ``CONFIG_IMA_X509_PATH`` and ``CONFIG_EVM_X509_PATH``.
+
+action
+~~~~~~
+
+   Determines what IPE should do when a rule matches. Must be in every
+   rule, as the final clause. Can be one of:
+
+   ``ALLOW``:
+
+      If the rule matches, explicitly allow access to the resource to proceed
+      without executing any more rules.
+
+   ``DENY``:
+
+      If the rule matches, explicitly prohibit access to the resource to
+      proceed without executing any more rules.
+
+boot_verified
+~~~~~~~~~~~~~
+
+   This property can be utilized for authorization of the first super-block
+   that executes a file. This is almost always init. Typically this is used
+   for systems with an initramfs or other initial disk, where this is unmounted
+   before the system becomes available, and is not covered by any other property.
+   The format of this property is::
+
+         boot_verified=(TRUE|FALSE)
+
+
+   .. WARNING::
+
+      This property will trust any disk where the first execution evaluation
+      occurs. If you do *NOT* have a startup disk that is unpacked and unmounted
+      (like initramfs), then it will automatically trust the root filesystem and
+      potentially overauthorize the entire disk.
+
+dmverity_roothash
+~~~~~~~~~~~~~~~~~
+
+   This property can be utilized for authorization or revocation of
+   specific dm-verity volumes, identified via root hash. It has a
+   dependency on the DM_VERITY module. This property is controlled by the
+   Kconfig ``CONFIG_IPE_PROP_DM_VERITY``. The format of this property
+   is::
+
+      dmverity_roothash=DigestName:HexadecimalString
+
+   The supported DigestNames for dmverity_roothash are [#dmveritydigests]_ [#securedigest]_ :
+
+      + blake2b-512
+      + blake2s-256
+      + sha1
+      + sha256
+      + sha384
+      + sha512
+      + sha3-224
+      + sha3-256
+      + sha3-384
+      + sha3-512
+      + md4
+      + md5
+      + sm3
+      + rmd160
+
+dmverity_signature
+~~~~~~~~~~~~~~~~~~
+
+   This property can be utilized for authorization of all dm-verity volumes
+   that have a signed roothash that chains to a keyring specified by dm-verity's
+   configuration, either the system trusted keyring, or the secondary keyring.
+   It has an additional dependency on the ``DM_VERITY_VERIFY_ROOTHASH_SIG``
+   Kconfig. This property is controlled by the Kconfig
+   ``CONFIG_IPE_PROP_DM_VERITY``. The format of this property is::
+
+      dmverity_signature=(TRUE|FALSE)
+
+fsverity_digest
+~~~~~~~~~~~~~~~
+
+   This property can be utilized for authorization or revocation of
+   specific fsverity enabled file, identified via its fsverity digest.
+   It has a dependency on the FS_VERITY module. This property is
+   controlled by the Kconfig ``CONFIG_IPE_PROP_FS_VERITY``.
+   The format of this property is::
+
+      fsverity_digest=DigestName:HexadecimalString
+
+   The supported DigestNames for dmverity_roothash are [#fsveritydigest] [#securedigest]_ :
+
+      + sha256
+      + sha512
+
+fsverity_signature
+~~~~~~~~~~~~~~~~~~
+
+Version 1
+
+   This property can be utilized for authorization of all fsverity enabled
+   files that is verified by fsverity. The keyring that the signature is
+   verified against is subject to fsverity's configuration, typically the fsverity
+   keyring. It has a dependency on the ``CONFIG_FS_VERITY_BUILTIN_SIGNATURES``
+   Kconfig. This property is controlled by the Kconfig
+   ``CONFIG_IPE_PROP_FS_VERITY``. The format of this property is::
+
+      fsverity_signature=(TRUE|FALSE)
+
+Policy Examples
+---------------
+
+Allow all
+~~~~~~~~~
+
+::
+
+   policy_name=Allow_All policy_version=0.0.0
+   DEFAULT action=ALLOW
+
+Allow only initial superblock
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+::
+
+   policy_name=Allow_All_Initial_SB policy_version=0.0.0
+   DEFAULT action=DENY
+
+   op=EXECUTE boot_verified=TRUE action=ALLOW
+
+Allow any signed dm-verity volume and the initial superblock
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+::
+
+   policy_name=AllowSignedAndInitial policy_version=0.0.0
+   DEFAULT action=DENY
+
+   op=EXECUTE boot_verified=TRUE action=ALLOW
+   op=EXECUTE dmverity_signature=TRUE action=ALLOW
+
+Prohibit execution from a specific dm-verity volume
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+::
+
+   policy_name=AllowSignedAndInitial policy_version=0.0.0
+   DEFAULT action=DENY
+
+   op=EXECUTE dmverity_roothash=sha256:cd2c5bae7c6c579edaae4353049d58eb5f2e8be0244bf05345bc8e5ed257baff action=DENY
+
+   op=EXECUTE boot_verified=TRUE action=ALLOW
+   op=EXECUTE dmverity_signature=TRUE action=ALLOW
+
+Allow only a specific dm-verity volume
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+::
+
+   policy_name=AllowSignedAndInitial policy_version=0.0.0
+   DEFAULT action=DENY
+
+   op=EXECUTE dmverity_roothash=sha256:401fcec5944823ae12f62726e8184407a5fa9599783f030dec146938 action=ALLOW
+
+Allow any signed fs-verity file
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+::
+
+   policy_name=AllowSignedFSVerity policy_version=0.0.0
+   DEFAULT action=DENY
+
+   op=EXECUTE fsverity_signature=TRUE action=ALLOW
+
+Prohibit execution of a specific fs-verity file
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+::
+
+   policy_name=ProhibitSpecificFSVF policy_version=0.0.0
+   DEFAULT action=DENY
+
+   op=EXECUTE fsverity_digest=sha256:fd88f2b8824e197f850bf4c5109bea5cf0ee38104f710843bb72da796ba5af9e action=DENY
+   op=EXECUTE boot_verified=TRUE action=ALLOW
+   op=EXECUTE dmverity_signature=TRUE action=ALLOW
+
+Additional Information
+----------------------
+
+- `Github Repository <https://github.com/microsoft/ipe>`_
+- `Design Documentation </security/ipe>`_
+
+FAQ
+---
+
+Q:
+   What's the difference between other LSMs which provide a measure of
+   trust-based access control?
+
+A:
+
+   In general, there's two other LSMs that can provide similar functionality:
+   IMA, and Loadpin.
+
+   IMA and IPE are functionally very similar. The significant difference between
+   the two is the policy. [#devdoc]_
+
+   Loadpin and IPE differ fairly dramatically, as Loadpin controls only the IPE
+   equivalent of ``KERNEL_READ``, whereas IPE is capable of controlling execution,
+   on top of ``KERNEL_READ``. The trust model is also different; Loadpin roots its
+   trust in the initial super-block, instead, IPE roots its trust in the kernel
+   itself (via ``SYSTEM_TRUSTED_KEYS``).
+
+-----------
+
+.. [#diglim] 1: https://lore.kernel.org/bpf/[e-mail]/T/
+
+.. [#interpreters] There is `some interest in solving this issue <https://lore.kernel.org/lkml/[e-mail]/>`_.
+
+.. [#devdoc] Please see `Documentation/security/ipe.rst` for more on this topic.
+
+.. [#fsveritydigest] These hash algorithms are based on values accepted by fsverity-utils;
+                     IPE does not impose any restrictions on the digest algorithm itself;
+                     thus, this list may be out of date.
+
+.. [#dmveritydigests] These hash algorithms are based on values accepted by dm-verity,
+                      specifically ``crypto_alloc_ahash`` in ``verity_ctr``; ``veritysetup``
+                      does support more algorithms than the list above. IPE does not impose
+                      any restrictions on the digest algorithm itself; thus, this list
+                      may be out of date.
+
+.. [#securedigest] Please ensure you are using cryptographically secure hash functions;
+                   just because something is *supported* does not mean it is *secure*.
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index 6cfa6e3996cf..6f2868113135 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -2209,6 +2209,18 @@ 
 	ipcmni_extend	[KNL] Extend the maximum number of unique System V
 			IPC identifiers from 32,768 to 16,777,216.
 
+	ipe.enforce=	[IPE]
+			Format: <bool>
+			Determine whether IPE starts in permissive (0) or
+			enforce (1) mode. The default is enforce.
+
+	ipe.success_audit=
+			[IPE]
+			Format: <bool>
+			Start IPE with success auditing enabled, emitting
+			an audit event when a binary is allowed. The default
+			is 0.
+
 	irqaffinity=	[SMP] Set the default irq affinity mask
 			The argument is a cpu list, as described above.
 
diff --git a/Documentation/security/index.rst b/Documentation/security/index.rst
index 6ed8d2fa6f9e..a5248d4fd510 100644
--- a/Documentation/security/index.rst
+++ b/Documentation/security/index.rst
@@ -18,3 +18,4 @@  Security Documentation
    digsig
    landlock
    secrets/index
+   ipe
diff --git a/Documentation/security/ipe.rst b/Documentation/security/ipe.rst
new file mode 100644
index 000000000000..85e170ce864a
--- /dev/null
+++ b/Documentation/security/ipe.rst
@@ -0,0 +1,436 @@ 
+.. SPDX-License-Identifier: GPL-2.0
+
+Integrity Policy Enforcement (IPE) - Kernel Documentation
+=========================================================
+
+.. NOTE::
+
+   This is documentation targeted at developers, instead of administrators.
+   If you're looking for documentation on the usage of IPE, please see
+   `Documentation/admin-guide/LSM/ipe.rst`
+
+Historical Motivation
+---------------------
+
+The original issue that prompted IPE's implementation was the creation
+of a locked-down system. This system would be born-secure, and have
+strong integrity guarantees over both the executable code, and specific
+*data files* on the system, that were critical to its function. These
+specific data files would not be readable unless they passed integrity
+policy. A mandatory access control system would be present, and
+as a result, xattrs would have to be protected. This lead to a selection
+of what would provide the integrity claims. At the time, there were two
+main mechanisms considered that could guarantee integrity for the system
+with these requirements:
+
+  1. IMA + EVM Signatures
+  2. DM-Verity
+
+Both options were carefully considered, however the choice to use DM-Verity
+over IMA+EVM as the *integrity mechanism* in the original use case of IPE
+was due to three main reasons:
+
+  1. Protection of additional attack vectors:
+
+    * With IMA+EVM, without an encryption solution, the system is vulnerable
+      to offline attack against the aforemetioned specific data files.
+
+      Unlike executables, read operations (like those on the protected data
+      files), cannot be enforced to be globally integrtiy verified. This means
+      there must be some form of selector to determine whether a read should
+      enforce the integrity policy, or it should not.
+
+      At the time, this was done with mandatory access control labels. An IMA
+      policy would indicate what labels required integrity verification, which
+      presented an issue: EVM would protect the label, but if an attacker could
+      modify filesystem offline, the attacker could wipe all the xattrs -
+      including the SELinux labels that would be used to determine whether the
+      file should be subject to integrity policy.
+
+      With DM-Verity, as the xattrs are saved as part of the merkel tree, if
+      offline mount occurs against the filesystem protected by dm-verity, the
+      checksum no longer matches and the file fails to be read.
+
+    * As userspace binaries are paged in Linux, dm-verity also offers the
+      additional protection against a hostile block device. In such an attack,
+      the block device reports the appropriate content for the IMA hash
+      initially, passing the required integrity check. Then, on the page fault
+      that accesses the real data, will report the attacker's payload. Since
+      dm-verity will check the data when the page fault occurs (and the disk
+      access), this attack is mitigated.
+
+  2. Performance:
+
+    * dm-verity provides integrity verification on demand as blocks are
+      read versus requiring the entire file being read into memory for
+      validation.
+
+  3. Simplicity of signing:
+
+    * No need for two signatures (IMA, then EVM): one signature covers
+      an entire block device.
+    * Signatures can be stored externally to the filesystem metadata.
+    * The signature supports an x.509-based signing infrastructure.
+
+The next step was to choose a *policy* to enforce the integrity mechanism.
+The minimum requirements for the policy were:
+
+  1. The policy itself must be integrity verified (preventing trivial
+     attack against it).
+  2. The policy itself must be resistant to rollback attacks.
+  3. The policy enforcement must have a permissive-like mode.
+  4. The policy must be able to be updated, in its entirety, without
+     a reboot.
+  5. Policy updates must be atomic.
+  6. The policy must support *revocations* of previously authored
+     components.
+  7. The policy must be auditable, at any point-of-time.
+
+IMA, as the only integrity policy mechanism at the time, was
+considered against these list of requirements, and did not fulfill
+all of the minimum requirements. Extending IMA to cover these
+requirements was considered, but ultimately discarded for a
+two reasons:
+
+  1. Regression risk; many of these changes would result in
+     dramatic code changes to IMA, which is already present in the
+     kernel, and therefore might impact users.
+
+  2. IMA was used in the system for measurement and attestation;
+     separation of measurement policy from local integrity policy
+     enforcement was considered favorable.
+
+Due to these reasons, it was decided that a new LSM should be created,
+whose responsibility would be only the local integrity policy enforcement.
+
+Role and Scope
+--------------
+
+IPE, as its name implies, is fundamentally an integrity policy enforcement
+solution; IPE does not mandate how integrity is provided, but instead
+leaves that decision to the system administrator to set the security bar,
+via the mechanisms that they select that suit their individual needs.
+There are several different integrity solutions that provide a different
+level of security guarantees; and IPE allows sysadmins to express policy for
+theoretically all of them.
+
+IPE additionally does not provide a mechanism that provides integrity
+by itself: there are better layers to create such systems, and a mechanism
+of proving integrity has next to nothing to do with the policy of enforcing
+that integrity claim.
+
+Therefore, IPE was designed around:
+
+  1. Easy integrations with integrity providers.
+  2. Ease of use for platform administrators/sysadmins.
+
+Design Rationale:
+-----------------
+
+IPE was designed after evluating existing integrity policy solutions
+in other operating systems and environments. In this survey of other
+implementations, there were a few pitfalls identified:
+
+  1. Policies were not readable by humans, usually requiring a binary
+     intermediary format.
+  2. A single, non-customizable action was implicitly taken as a default.
+  3. Debugging the policy required manual steps to determine what rule was violated.
+  4. Authoring a policy required an in-depth knowledge of the larger system,
+     or operating system.
+
+IPE attempts to avoid all of these pitfalls.
+
+Policy
+~~~~~~
+
+Plain Text
+^^^^^^^^^^
+
+IPE's policy is plain-text. This introduces slightly larger policy files than
+other LSMs, but solves two major problems that occurs with some integrity policy
+solutions on other platforms.
+
+The first issue is one of code maintenance and duplication. To author policies,
+the policy has to be some form of string representation (be it structured,
+through XML, JSON, YAML, etcetera), to allow the policy author to understand
+what is being written. In a hypothetical binary policy design, a serializer
+is necessary to write the policy from the human readable form, to the binary
+form, and a deserializer is needed to interpret the binary form into a data
+structure in the kernel.
+
+Eventually, another deserializer will be needed to transform the binary from
+back into the human-readable form with as much information preserved. This is because a
+user of this access control system will have to keep a lookup table of a checksum
+and the original file itself to try to understand what policies have been deployed
+on this system and what policies have not. For a single user, this may be alright,
+as old policies can be discarded almost immediately after the update takes hold.
+For users that manage computer fleets in the thousands, if not hundreds of thousands,
+with multiple different operating systems, and multiple different operational needs,
+this quickly becomes an issue, as stale policies from years ago may be present,
+quickly resulting in the need to recover the policy or fund extensive infrastructure
+to track what each policy contains.
+
+With now three separate serializer/deserializers, maintenance becomes costly. If the
+policy avoids the binary format, there is only one required serializer: from the
+human-readable form to the data structure ine kernel, saving on code maintenance,
+and retaining operability.
+
+The second issue with a binary format is one of transparency. As IPE controls
+access based on the trust of the system's resources, it's policy must also be
+trusted to be changed. This is done through signatures, resulting in needing
+signing as a process. Signing, as a process, is typically done with a
+high security bar, as anything signed can be used to attack integrity
+enforcement systems. It is also important that, when signing something, that
+the signer is aware of what they are signing. A binary policy can cause
+obfuscation of that fact; what signers see is an opaque binary blob. A
+plain-text policy, on the other hand, the signers see the actual policy
+submitted for signing.
+
+Boot Policy
+~~~~~~~~~~~
+
+IPE, if configured appropriately, is able to enforce a policy as soon as a
+kernel is booted and usermode starts. That implies some level of storage
+of the policy to apply the minute usermode starts. Generally, that storage
+can be handled in one of three ways:
+
+  1. The policy file(s) live on disk and the kernel loads the policy prior
+     to an code path that would result in an enforcement decision.
+  2. The policy file(s) are passed by the bootloader to the kernel, who
+     parses the policy.
+  3. There is a policy file that is compiled into the kernel that is
+     parsed and enforced on initialization.
+
+The first option has problems: the kernel reading files from userspace
+is typically discouraged and very uncommon in the kernel.
+
+The second option also has problems: Linux supports a variety of bootloaders
+across its entire ecosystem - every bootloader would have to support this
+new methodology or there must be an independent source. It would likely
+result in more drastic changes to the kernel startup than necessary.
+
+The third option is the best but it's important to be aware that the policy
+will take disk space against the kernel it's compiled in. It's important to
+keep this policy generalized enough that userspace can load a new, more
+complicated policy, but restrictive enough that it will not overauthorize
+and cause security issues.
+
+The initramfs provides a way that this bootup path can be established. The
+kernel starts with a minimal policy, that trusts the initramfs only. Inside
+the initramfs, when the real rootfs is mounted, but not yet transferred to,
+it deploys and activates a policy that trusts the new root filesystem.
+This prevents overauthorization at any step, and keeps the kernel policy
+to a minimal size.
+
+Startup
+^^^^^^^
+
+Not every system, however starts with an initramfs, so the startup policy
+compiled into the kernel will need some flexibility to express how trust
+is established for the next phase of the bootup. To this end, if we just
+make the compiled-in policy a full IPE policy, it allows system builders
+to express the first stage bootup requirements appropriately.
+
+Updatable, Rebootless Policy
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+As requirements change over time (vulnerabilities are found in previously
+trusted applcations, keys roll, etcetera). Updating a kernel to change the
+meet those security goals is not always a suitable option, as updates are not
+always risk-free, and blocking a security update leaves systems vulnerable.
+This means IPE requires a policy that can be completely updated (allowing
+revocations of existing policy) from a source external to the kernel (allowing
+policies to be updated without updating the kernel).
+
+Additionally, since the kernel is stateless between invocations, and reading
+policy files off the disk from kernel space is a bad idea(tm), then the
+policy updates have to be done rebootlessly.
+
+To allow an update from an external source, it could be potentially malicious,
+so this policy needs to have a way to be identified as trusted. This is
+done via a signature chained to a trust source in the kernel. Arbitrarily,
+this is  the ``SYSTEM_TRUSTED_KEYRING``, a keyring that is initially
+populated at kernel compile-time, as this matches the expectation that the
+author of the compiled-in policy described above is the same entity that can
+deploy policy updates.
+
+Anti-Rollback / Anti-Replay
+~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+Over time, vulnerabilities are found and trusted resources may not be
+trusted anymore. IPE's policy has no exception to this. There can be
+instances where a mistaken policy author deploys an insecure policy,
+before correcting it with a secure policy.
+
+Assuming that as soon as the insecure policy is signed, and an attacker
+acquires the insecure policy, IPE needs a way to prevent rollback
+from the secure policy update to the insecure policy update.
+
+Initially, IPE's policy can have a policy_version that states the
+minimum required version across all policies that can be active on
+the system. This will prevent rollback while the system is live.
+
+.. WARNING::
+
+  However, since the kernel is stateless across boots, this policy
+  version will be reset to 0.0.0 on the next boot. System builders
+  need to be aware of this, and ensure the new secure policies are
+  deployed ASAP after a boot to ensure that the window of
+  opportunity is minimal for an attacker to deploy the insecure policy.
+
+Implicit Actions:
+~~~~~~~~~~~~~~~~~
+
+The issue of impicit actions only becomes visible when you consider
+a mixed level of security bars across multiple operations in a system.
+For example, consider a system that has strong integrity guarantees
+over both the executable code, and specific *data files* on the system,
+that were critical to its function. In this system, three types of policies
+are possible:
+
+  1. A policy in which failure to match any rules in the policy results
+     in the action being denied.
+  2. A policy in which failure to match any rules in the policy results
+     in the action being allowed.
+  3. A policy in which the action taken when no rules are matched is
+     specified by the policy author.
+
+The first option could make a policy like this::
+
+  op=EXECUTE integrity_verified=YES action=DENY
+
+In the example system, this works well for the executables, as all
+executables should have integrity guarantees, without exception. The
+issue becomes with the second requirement about specific data files.
+This would result in a policy like this (assuming each line is
+evaluated in order)::
+
+  op=EXECUTE integrity_verified=YES action=DENY
+
+  op=READ integrity_verified=NO label=critical_t action=DENY
+  op=READ action=ALLOW
+
+This is somewhat clear if you read the docs, understand the policy
+is executed in order and that the default is a denial; however, the
+last line effectively changes that default to an ALLOW. This is
+required, because in a realistic system, there are some unverified
+reads (imagine appending to a log file).
+
+The second option, matching no rules results in an allow, is clearer
+for the specific data files::
+
+  op=READ integrity_verified=NO label=critical_t action=DENY
+
+And, like the first option, falls short with the opposite scenario,
+effectively needing to override the default::
+
+  op=EXECUTE integrity_verified=YES action=ALLOW
+  op=EXECUTE action=DENY
+
+  op=READ integrity_verified=NO label=critical_t action=DENY
+
+This leaves the third option. Instead of making users be clever
+and override the default with an empty rule, force the end-user
+to consider what the appropriate default should be for their
+scenario and explicitly state it::
+
+  DEFAULT op=EXECUTE action=DENY
+  op=EXECUTE integrity_verified=YES action=ALLOW
+
+  DEFAULT op=READ action=ALLOW
+  op=READ integrity_verified=NO label=critical_t action=DENY
+
+Policy Debugging:
+~~~~~~~~~~~~~~~~~
+
+When developing a policy, it is useful to know what line of the policy
+is being violated to reduce debugging costs; narrowing the scope of the
+investigation to the exact line that resulted in the action. Some integrity
+policy systems do not provide this information, instead providing the
+information that was used in the evaluation. This then requires a correlation
+with the policy to evaluate what went wrong.
+
+Instead, IPE just emits the rule that was matched. This limits the scope
+of the investigation to the exact policy line (in the case of a specific
+rule), or the section (in the case of a DEFAULT). This decreases iteration
+and investigation times when policy failures are observed while evaluating
+policies.
+
+IPE's policy engine is also designed in a way that it makes it obvious to
+a human of how to investigate a policy failure. Each line is evaluated in
+the sequence that is written, so the algorithm is very simple to follow
+for humans to recreate the steps and could have caused the failure. In other
+surveyed systems, optimizations occur (sorting rules, for instance) when loading
+the policy. In those systems, it requires multiple steps to debug, and the
+algorithm may not always be clear to the end-user without reading the code first.
+
+Simplified Policy:
+~~~~~~~~~~~~~~~~~~
+
+Finally, IPE's policy is designed for sysadmins, not kernel developers. Instead
+of covering individual LSM hooks (or syscalls), IPE covers operations. This means
+instead of sysadmins needing to know that the syscalls ``mmap``, ``mprotect``,
+``execve``, and ``uselib`` must have rules protecting them, they must simple know
+that they want to restrict code execution. This limits the amount of bypasses that
+could occur due to a lack of knowledge of the underlying system; whereas the
+maintainers of IPE, being kernel developers can make the correct choice to determine
+whether something maps to these operations, and under what conditions.
+
+Implementation Notes
+--------------------
+
+Anonymous Memory
+~~~~~~~~~~~~~~~~
+
+Anonymous memory isn't treated any differently from any other access in IPE.
+When anonymous memory is mapped with ``+X``, it still comes into the ``file_mmap``
+or ``file_mprotect`` hook, but with a ``NULL`` file object. This is submitted to
+the evaluation, like any other file, however, all current trust mechanisms will
+return false as there is nothing to evaluate. This means anonymous memory
+execution is subject to whatever the ``DEFAULT`` is for ``EXECUTE``.
+
+.. WARNING::
+
+  This also occurs with the ``kernel_load_data`` hook, which is used by signed
+  and compressed kernel modules. Using signed and compressed kernel modules with
+  IPE will always result in the ``DEFAULT`` action for ``KMODULE``.
+
+Securityfs Interface
+~~~~~~~~~~~~~~~~~~~~
+
+The per-policy securityfs tree is somewhat unique. For example, for
+a standard securityfs policy tree::
+
+  MyPolicy
+    |- active
+    |- raw
+    |- policy
+    |- name
+    |- version
+    |- update
+
+The policy is stored in the ``->i_private`` data of the MyPolicy inode,
+while each child's ``->i_private``, it stores the MyPolicy inode. This
+simplifies policy updates massively, as the alternative designs are to:
+
+  1. Use d_parent, which has potential issues with flexibility, if there
+     eventually becomes a subdirectory underneath MyPolicy; as it's unclear
+     how many levels of ``d_parent`` you have to iterate up to.
+
+  2. Store the policy data in each inode's ``->i_private``. This has issues
+     when it comes to updating a policy - every update needs to cascade to
+     each ``->i_private``, and if it fails, for whatever reason, the
+     operation has to be reverted on each inode.
+
+With this implementation, you can solve the flexibility problem of 1, as
+now when you create a theoretical subdirectory you just set the
+``->i_private`` data appropriately. You also solve the update problem of
+two, as you simply update or revert on the one inode that all other inodes
+reference.
+
+Tests
+-----
+
+IPE has KUnit Tests, testing primarily the parser. In addition, IPE has a
+python based integration test suits that can test both user interfaces and
+enforcement functionalities.
diff --git a/MAINTAINERS b/MAINTAINERS
index d5b4a6636b0d..969c6a7845ed 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -10276,6 +10276,8 @@  F:	security/integrity/
 INTEGRITY POLICY ENFORCEMENT (IPE)
 M:	Fan Wu <[e-mail]>
 S:	Supported
+F:	Documentation/admin-guide/LSM/ipe.rst
+F:	Documentation/security/ipe.rst
 F:	scripts/ipe/
 F:	security/ipe/