Re: [PATCH v16 01/20] security: add ipe lsm

Jarkko Sakkinen
2024-03-28T20:45:35Z

On Thu Mar 28, 2024 at 10:17 PM EET, Fan Wu wrote:
> From: Deven Bowers <deven.desai@linux.microsoft.com>
>
> 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@linux.microsoft.com>
> Signed-off-by: Fan Wu <wufan@linux.microsoft.com>
> ---
> 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
>
> v15:
> + Add missing code in tools/testing/selftests/lsm/lsm_list_modules_test.c
>
> v16:
> + 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 +-
> .../selftests/lsm/lsm_list_modules_test.c | 3 ++
> 10 files changed, 103 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 079a86e680bc..16e29f2361c9 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -10744,6 +10744,13 @@ 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@linux.microsoft.com>
> +L: linux-security-module@vger.kernel.org
> +S: Supported
> +T: git https://github.com/microsoft/ipe.git
> +F: security/ipe/
> +
> INTEL 810/815 FRAMEBUFFER DRIVER
> M: Antonino Daplas <adaplas@gmail.com>
> L: linux-fbdev@vger.kernel.org

MAINTAINER updates should be split into separate commits, preferably to
the tail of the series because it is stamp for the full feature not a
subportion of it.

> diff --git a/include/uapi/linux/lsm.h b/include/uapi/linux/lsm.h
> index 33d8c9f4aa6b..938593dfd5da 100644
> --- a/include/uapi/linux/lsm.h
> +++ b/include/uapi/linux/lsm.h
> @@ -64,6 +64,7 @@ struct lsm_ctx {
> #define LSM_ID_LANDLOCK 110
> #define LSM_ID_IMA 111
> #define LSM_ID_EVM 112
> +#define LSM_ID_IPE 113
>
> /*
> * LSM_ATTR_XXX definitions identify different LSM attributes
> diff --git a/security/Kconfig b/security/Kconfig
> index 412e76f1575d..9fb8f9b14972 100644
> --- a/security/Kconfig
> +++ b/security/Kconfig
> @@ -192,6 +192,7 @@ source "security/yama/Kconfig"
> source "security/safesetid/Kconfig"
> source "security/lockdown/Kconfig"
> source "security/landlock/Kconfig"
> +source "security/ipe/Kconfig"
>
> source "security/integrity/Kconfig"
>
> @@ -231,11 +232,11 @@ 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>
> +

Not sure if this new line adds any clarity but you can keep it if you
want I neither mind that much.

> +#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

Just a suggestion:

* 0: OK
* -ENOMEM: Out of memory (OOM)

Rationale being more readable (less convoluted).

And also sort of symmetrical how parameters are formatted in kdoc.

> + */
> +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

s/IPE/ipe/

> +
> +#include <linux/lsm_hooks.h>
> +
> +#endif /* _IPE_H */
> diff --git a/security/security.c b/security/security.c
> index 7e118858b545..287bfac6b471 100644
> --- a/security/security.c
> +++ b/security/security.c
> @@ -51,7 +51,8 @@
> (IS_ENABLED(CONFIG_BPF_LSM) ? 1 : 0) + \
> (IS_ENABLED(CONFIG_SECURITY_LANDLOCK) ? 1 : 0) + \
> (IS_ENABLED(CONFIG_IMA) ? 1 : 0) + \
> - (IS_ENABLED(CONFIG_EVM) ? 1 : 0))
> + (IS_ENABLED(CONFIG_EVM) ? 1 : 0) + \
> + (IS_ENABLED(CONFIG_SECURITY_IPE) ? 1 : 0))
>
> /*
> * These are descriptions of the reasons that can be passed to the
> diff --git a/tools/testing/selftests/lsm/lsm_list_modules_test.c b/tools/testing/selftests/lsm/lsm_list_modules_test.c
> index 06d24d4679a6..1cc8a977c711 100644
> --- a/tools/testing/selftests/lsm/lsm_list_modules_test.c
> +++ b/tools/testing/selftests/lsm/lsm_list_modules_test.c
> @@ -128,6 +128,9 @@ TEST(correct_lsm_list_modules)
> case LSM_ID_EVM:
> name = "evm";
> break;
> + case LSM_ID_IPE:
> + name = "ipe";
> + break;
> default:
> name = "INVALID";
> break;

BR, Jarkko