Re: [RFC PATCH v14 01/19] security: add ipe lsm

[Roberto Sassu]

On Wed, 2024-03-06 at 15:34 -0800, Fan Wu wrote:
> From: Deven Bowers <deven.desai@xxxxxxxxxxxxxxxxxxx>
> 
> Integrity Policy Enforcement (IPE) is an LSM that provides an
> complimentary approach to Mandatory Access Control than existing LSMs
> today.
> 
> Existing LSMs have centered around the concept of access to a resource
> should be controlled by the current user's credentials. IPE's approach,
> is that access to a resource should be controlled by the system's trust
> of a current resource.
> 
> The basis of this approach is defining a global policy to specify which
> resource can be trusted.
> 
> Signed-off-by: Deven Bowers <deven.desai@xxxxxxxxxxxxxxxxxxx>
> Signed-off-by: Fan Wu <wufan@xxxxxxxxxxxxxxxxxxx>
> ---
> v2:
>   + Split evaluation loop, access control hooks,
>     and evaluation loop from policy parser and userspace
>     interface to pass mailing list character limit
> 
> v3:
>   + Move ipe_load_properties to patch 04.
>   + Remove useless 0-initializations
>   + Prefix extern variables with ipe_
>   + Remove kernel module parameters, as these are
>     exposed through sysctls.
>   + Add more prose to the IPE base config option
>     help text.
>   + Use GFP_KERNEL for audit_log_start.
>   + Remove unnecessary caching system.
>   + Remove comments from headers
>   + Use rcu_access_pointer for rcu-pointer null check
>   + Remove usage of reqprot; use prot only.
>   + Move policy load and activation audit event to 03/12
> 
> v4:
>   + Remove sysctls in favor of securityfs nodes
>   + Re-add kernel module parameters, as these are now
>     exposed through securityfs.
>   + Refactor property audit loop to a separate function.
> 
> v5:
>   + fix minor grammatical errors
>   + do not group rule by curly-brace in audit record,
>     reconstruct the exact rule.
> 
> v6:
>   + No changes
> 
> v7:
>   + Further split lsm creation into a separate commit from the
>     evaluation loop and audit system, for easier review.
> 
>   + Introduce the concept of an ipe_context, a scoped way to
>     introduce execution policies, used initially for allowing for
>     kunit tests in isolation.
> 
> v8:
>   + Follow lsmname_hook_name convention for lsm hooks.
>   + Move LSM blob accessors to ipe.c and mark LSM blobs as static.
> 
> v9:
>   + Remove ipe_context for simplification
> 
> v10:
>   + Add github url
> 
> v11:
>   + Correct github url
>   + Move ipe before bpf
> 
> v12:
>   + Switch to use lsm_id instead of string for lsm name
> 
> v13:
>   + No changes
> 
> v14:
>   + No changes
> ---
>  MAINTAINERS              |  7 +++++++
>  include/uapi/linux/lsm.h |  1 +
>  security/Kconfig         | 11 ++++++-----
>  security/Makefile        |  1 +
>  security/ipe/Kconfig     | 17 +++++++++++++++++
>  security/ipe/Makefile    |  9 +++++++++
>  security/ipe/ipe.c       | 41 ++++++++++++++++++++++++++++++++++++++++
>  security/ipe/ipe.h       | 16 ++++++++++++++++
>  security/security.c      |  3 ++-
>  9 files changed, 100 insertions(+), 6 deletions(-)
>  create mode 100644 security/ipe/Kconfig
>  create mode 100644 security/ipe/Makefile
>  create mode 100644 security/ipe/ipe.c
>  create mode 100644 security/ipe/ipe.h
> 
> diff --git a/MAINTAINERS b/MAINTAINERS
> index 13158047f2af..8517011f88ff 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -10650,6 +10650,13 @@ T:	git git://git.kernel.org/pub/scm/linux/kernel/git/zohar/linux-integrity.git
>  F:	security/integrity/
>  F:	security/integrity/ima/
>  
> +INTEGRITY POLICY ENFORCEMENT (IPE)
> +M:	Fan Wu <wufan@xxxxxxxxxxxxxxxxxxx>
> +L:	linux-security-module@xxxxxxxxxxxxxxx
> +S:	Supported
> +T:	git https://github.com/microsoft/ipe.git
> +F:	security/ipe/
> +
>  INTEL 810/815 FRAMEBUFFER DRIVER
>  M:	Antonino Daplas <adaplas@xxxxxxxxx>
>  L:	linux-fbdev@xxxxxxxxxxxxxxx
> diff --git a/include/uapi/linux/lsm.h b/include/uapi/linux/lsm.h
> index f8aef9ade549..43e2fb32745a 100644
> --- a/include/uapi/linux/lsm.h
> +++ b/include/uapi/linux/lsm.h
> @@ -62,6 +62,7 @@ struct lsm_ctx {
>  #define LSM_ID_LOCKDOWN		108
>  #define LSM_ID_BPF		109
>  #define LSM_ID_LANDLOCK		110
> +#define LSM_ID_IPE		111
>  
>  /*
>   * LSM_ATTR_XXX definitions identify different LSM attributes
> diff --git a/security/Kconfig b/security/Kconfig
> index 52c9af08ad35..cc7adfbb6b96 100644
> --- a/security/Kconfig
> +++ b/security/Kconfig
> @@ -194,6 +194,7 @@ source "security/yama/Kconfig"
>  source "security/safesetid/Kconfig"
>  source "security/lockdown/Kconfig"
>  source "security/landlock/Kconfig"
> +source "security/ipe/Kconfig"
>  
>  source "security/integrity/Kconfig"
>  
> @@ -233,11 +234,11 @@ endchoice
>  
>  config LSM
>  	string "Ordered list of enabled LSMs"
> -	default "landlock,lockdown,yama,loadpin,safesetid,smack,selinux,tomoyo,apparmor,bpf" if DEFAULT_SECURITY_SMACK
> -	default "landlock,lockdown,yama,loadpin,safesetid,apparmor,selinux,smack,tomoyo,bpf" if DEFAULT_SECURITY_APPARMOR
> -	default "landlock,lockdown,yama,loadpin,safesetid,tomoyo,bpf" if DEFAULT_SECURITY_TOMOYO
> -	default "landlock,lockdown,yama,loadpin,safesetid,bpf" if DEFAULT_SECURITY_DAC
> -	default "landlock,lockdown,yama,loadpin,safesetid,selinux,smack,tomoyo,apparmor,bpf"
> +	default "landlock,lockdown,yama,loadpin,safesetid,smack,selinux,tomoyo,apparmor,ipe,bpf" if DEFAULT_SECURITY_SMACK
> +	default "landlock,lockdown,yama,loadpin,safesetid,apparmor,selinux,smack,tomoyo,ipe,bpf" if DEFAULT_SECURITY_APPARMOR
> +	default "landlock,lockdown,yama,loadpin,safesetid,tomoyo,ipe,bpf" if DEFAULT_SECURITY_TOMOYO
> +	default "landlock,lockdown,yama,loadpin,safesetid,ipe,bpf" if DEFAULT_SECURITY_DAC
> +	default "landlock,lockdown,yama,loadpin,safesetid,selinux,smack,tomoyo,apparmor,ipe,bpf"
>  	help
>  	  A comma-separated list of LSMs, in initialization order.
>  	  Any LSMs left off this list, except for those with order
> diff --git a/security/Makefile b/security/Makefile
> index 59f238490665..cc0982214b84 100644
> --- a/security/Makefile
> +++ b/security/Makefile
> @@ -25,6 +25,7 @@ obj-$(CONFIG_SECURITY_LOCKDOWN_LSM)	+= lockdown/
>  obj-$(CONFIG_CGROUPS)			+= device_cgroup.o
>  obj-$(CONFIG_BPF_LSM)			+= bpf/
>  obj-$(CONFIG_SECURITY_LANDLOCK)		+= landlock/
> +obj-$(CONFIG_SECURITY_IPE)		+= ipe/
>  
>  # Object integrity file lists
>  obj-$(CONFIG_INTEGRITY)			+= integrity/
> diff --git a/security/ipe/Kconfig b/security/ipe/Kconfig
> new file mode 100644
> index 000000000000..e4875fb04883
> --- /dev/null
> +++ b/security/ipe/Kconfig
> @@ -0,0 +1,17 @@
> +# SPDX-License-Identifier: GPL-2.0-only
> +#
> +# Integrity Policy Enforcement (IPE) configuration
> +#
> +
> +menuconfig SECURITY_IPE
> +	bool "Integrity Policy Enforcement (IPE)"
> +	depends on SECURITY && SECURITYFS
> +	select PKCS7_MESSAGE_PARSER
> +	select SYSTEM_DATA_VERIFICATION
> +	help
> +	  This option enables the Integrity Policy Enforcement LSM
> +	  allowing users to define a policy to enforce a trust-based access
> +	  control. A key feature of IPE is a customizable policy to allow
> +	  admins to reconfigure trust requirements on the fly.
> +
> +	  If unsure, answer N.
> diff --git a/security/ipe/Makefile b/security/ipe/Makefile
> new file mode 100644
> index 000000000000..f7a80d0f18f8
> --- /dev/null
> +++ b/security/ipe/Makefile
> @@ -0,0 +1,9 @@
> +# SPDX-License-Identifier: GPL-2.0
> +#
> +# Copyright (C) Microsoft Corporation. All rights reserved.
> +#
> +# Makefile for building the IPE module as part of the kernel tree.
> +#
> +
> +obj-$(CONFIG_SECURITY_IPE) += \
> +	ipe.o \
> diff --git a/security/ipe/ipe.c b/security/ipe/ipe.c
> new file mode 100644
> index 000000000000..b013aed15e73
> --- /dev/null
> +++ b/security/ipe/ipe.c
> @@ -0,0 +1,41 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Copyright (C) Microsoft Corporation. All rights reserved.
> + */
> +#include <uapi/linux/lsm.h>
> +
> +#include "ipe.h"
> +
> +static struct lsm_blob_sizes ipe_blobs __ro_after_init = {
> +};
> +
> +static const struct lsm_id ipe_lsmid = {
> +	.name = "ipe",
> +	.id = LSM_ID_IPE,
> +};
> +
> +static struct security_hook_list ipe_hooks[] __ro_after_init = {
> +};
> +
> +/**
> + * ipe_init - Entry point of IPE.
> + *
> + * This is called at LSM init, which happens occurs early during kernel
> + * start up. During this phase, IPE registers its hooks and loads the
> + * builtin boot policy.
> + * Return:
> + * * 0		- OK
> + * * -ENOMEM	- Out of memory
> + */
> +static int __init ipe_init(void)
> +{
> +	security_add_hooks(ipe_hooks, ARRAY_SIZE(ipe_hooks), &ipe_lsmid);
> +
> +	return 0;
> +}
> +
> +DEFINE_LSM(ipe) = {
> +	.name = "ipe",
> +	.init = ipe_init,
> +	.blobs = &ipe_blobs,
> +};
> diff --git a/security/ipe/ipe.h b/security/ipe/ipe.h
> new file mode 100644
> index 000000000000..a1c68d0fc2e0
> --- /dev/null
> +++ b/security/ipe/ipe.h
> @@ -0,0 +1,16 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +/*
> + * Copyright (C) Microsoft Corporation. All rights reserved.
> + */
> +
> +#ifndef _IPE_H
> +#define _IPE_H
> +
> +#ifdef pr_fmt
> +#undef pr_fmt
> +#endif
> +#define pr_fmt(fmt) "IPE: " fmt
> +
> +#include <linux/lsm_hooks.h>
> +
> +#endif /* _IPE_H */
> diff --git a/security/security.c b/security/security.c
> index 7035ee35a393..f168bc30a60d 100644
> --- a/security/security.c
> +++ b/security/security.c
> @@ -51,7 +51,8 @@
>  	(IS_ENABLED(CONFIG_SECURITY_SAFESETID) ? 1 : 0) + \
>  	(IS_ENABLED(CONFIG_SECURITY_LOCKDOWN_LSM) ? 1 : 0) + \
>  	(IS_ENABLED(CONFIG_BPF_LSM) ? 1 : 0) + \
> -	(IS_ENABLED(CONFIG_SECURITY_LANDLOCK) ? 1 : 0))
> +	(IS_ENABLED(CONFIG_SECURITY_LANDLOCK) ? 1 : 0) + \
> +	(IS_ENABLED(CONFIG_SECURITY_IPE) ? 1 : 0))

Hi Fan

you would also need to update
tools/testing/selftests/lsm/lsm_list_modules_test.c.

Roberto
 
>  /*
>   * These are descriptions of the reasons that can be passed to the