From patchwork Tue May 26 20:53:13 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: =?utf-8?q?Micka=C3=ABl_Sala=C3=BCn?= X-Patchwork-Id: 11571321 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id DE42A739 for ; Tue, 26 May 2020 20:54:57 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id C7BE5208B8 for ; Tue, 26 May 2020 20:54:57 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2404301AbgEZUxo (ORCPT ); Tue, 26 May 2020 16:53:44 -0400 Received: from smtp-8faa.mail.infomaniak.ch ([83.166.143.170]:37993 "EHLO smtp-8faa.mail.infomaniak.ch" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2404189AbgEZUxj (ORCPT ); Tue, 26 May 2020 16:53:39 -0400 Received: from smtp-2-0001.mail.infomaniak.ch (unknown [10.5.36.108]) by smtp-3-3000.mail.infomaniak.ch (Postfix) with ESMTPS id 49WmQS3GBYzlhWjS; Tue, 26 May 2020 22:53:36 +0200 (CEST) Received: from localhost (unknown [94.23.54.103]) by smtp-2-0001.mail.infomaniak.ch (Postfix) with ESMTPA id 49WmQR6BKhzlh9lP; Tue, 26 May 2020 22:53:35 +0200 (CEST) From: =?utf-8?q?Micka=C3=ABl_Sala=C3=BCn?= To: linux-kernel@vger.kernel.org Cc: =?utf-8?q?Micka=C3=ABl_Sala=C3=BCn?= , Al Viro , Andy Lutomirski , Anton Ivanov , Arnd Bergmann , Casey Schaufler , James Morris , Jann Horn , Jeff Dike , Jonathan Corbet , Kees Cook , Michael Kerrisk , =?utf-8?q?Micka=C3=ABl_Sala=C3=BCn?= , Richard Weinberger , "Serge E . Hallyn" , Shuah Khan , Vincent Dagonneau , kernel-hardening@lists.openwall.com, linux-api@vger.kernel.org, linux-arch@vger.kernel.org, linux-doc@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-security-module@vger.kernel.org, x86@kernel.org Subject: [PATCH v18 03/12] landlock: Set up the security framework and manage credentials Date: Tue, 26 May 2020 22:53:13 +0200 Message-Id: <20200526205322.23465-4-mic@digikod.net> X-Mailer: git-send-email 2.26.2 In-Reply-To: <20200526205322.23465-1-mic@digikod.net> References: <20200526205322.23465-1-mic@digikod.net> MIME-Version: 1.0 X-Antivirus: Dr.Web (R) for Unix mail servers drweb plugin ver.6.0.2.8 X-Antivirus-Code: 0x100000 Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org A process credentials point to a Landlock domain, which is underneath implemented with a ruleset. In the following commits, this domain is used to check and enforce the ptrace and filesystem security policies. A domain is inherited from a parent to its child the same way a thread inherits a seccomp policy. Signed-off-by: Mickaël Salaün Cc: James Morris Cc: Jann Horn Cc: Kees Cook Cc: Serge E. Hallyn --- Changes since v17: * Constify returned domain pointers from landlock_get_current_domain() and landlock_get_task_domain() helpers. Changes since v15: * Optimize landlocked() for current thread. * Display the greeting message when everything is initialized. Changes since v14: * Uses pr_fmt from common.h . * Constify variables. * Remove useless NULL initialization. Changes since v13: * totally get ride of the seccomp dependency * only keep credential management and LSM setup. Previous changes: https://lore.kernel.org/lkml/20191104172146.30797-4-mic@digikod.net/ --- security/Kconfig | 10 +++---- security/landlock/Makefile | 3 +- security/landlock/common.h | 20 +++++++++++++ security/landlock/cred.c | 46 ++++++++++++++++++++++++++++++ security/landlock/cred.h | 58 ++++++++++++++++++++++++++++++++++++++ security/landlock/setup.c | 31 ++++++++++++++++++++ security/landlock/setup.h | 16 +++++++++++ 7 files changed, 178 insertions(+), 6 deletions(-) create mode 100644 security/landlock/common.h create mode 100644 security/landlock/cred.c create mode 100644 security/landlock/cred.h create mode 100644 security/landlock/setup.c create mode 100644 security/landlock/setup.h diff --git a/security/Kconfig b/security/Kconfig index 582fd777a757..a96ee1c7fd25 100644 --- a/security/Kconfig +++ b/security/Kconfig @@ -278,11 +278,11 @@ endchoice config LSM string "Ordered list of enabled LSMs" - default "lockdown,yama,loadpin,safesetid,integrity,smack,selinux,tomoyo,apparmor,bpf" if DEFAULT_SECURITY_SMACK - default "lockdown,yama,loadpin,safesetid,integrity,apparmor,selinux,smack,tomoyo,bpf" if DEFAULT_SECURITY_APPARMOR - default "lockdown,yama,loadpin,safesetid,integrity,tomoyo,bpf" if DEFAULT_SECURITY_TOMOYO - default "lockdown,yama,loadpin,safesetid,integrity,bpf" if DEFAULT_SECURITY_DAC - default "lockdown,yama,loadpin,safesetid,integrity,selinux,smack,tomoyo,apparmor,bpf" + default "landlock,lockdown,yama,loadpin,safesetid,integrity,smack,selinux,tomoyo,apparmor,bpf" if DEFAULT_SECURITY_SMACK + default "landlock,lockdown,yama,loadpin,safesetid,integrity,apparmor,selinux,smack,tomoyo,bpf" if DEFAULT_SECURITY_APPARMOR + default "landlock,lockdown,yama,loadpin,safesetid,integrity,tomoyo,bpf" if DEFAULT_SECURITY_TOMOYO + default "landlock,lockdown,yama,loadpin,safesetid,integrity,bpf" if DEFAULT_SECURITY_DAC + default "landlock,lockdown,yama,loadpin,safesetid,integrity,selinux,smack,tomoyo,apparmor,bpf" help A comma-separated list of LSMs, in initialization order. Any LSMs left off this list will be ignored. This can be diff --git a/security/landlock/Makefile b/security/landlock/Makefile index d846eba445bb..041ea242e627 100644 --- a/security/landlock/Makefile +++ b/security/landlock/Makefile @@ -1,3 +1,4 @@ obj-$(CONFIG_SECURITY_LANDLOCK) := landlock.o -landlock-y := object.o ruleset.o +landlock-y := setup.o object.o ruleset.o \ + cred.o diff --git a/security/landlock/common.h b/security/landlock/common.h new file mode 100644 index 000000000000..5dc0fe15707d --- /dev/null +++ b/security/landlock/common.h @@ -0,0 +1,20 @@ +/* SPDX-License-Identifier: GPL-2.0-only */ +/* + * Landlock LSM - Common constants and helpers + * + * Copyright © 2016-2020 Mickaël Salaün + * Copyright © 2018-2020 ANSSI + */ + +#ifndef _SECURITY_LANDLOCK_COMMON_H +#define _SECURITY_LANDLOCK_COMMON_H + +#define LANDLOCK_NAME "landlock" + +#ifdef pr_fmt +#undef pr_fmt +#endif + +#define pr_fmt(fmt) LANDLOCK_NAME ": " fmt + +#endif /* _SECURITY_LANDLOCK_COMMON_H */ diff --git a/security/landlock/cred.c b/security/landlock/cred.c new file mode 100644 index 000000000000..7074149d2517 --- /dev/null +++ b/security/landlock/cred.c @@ -0,0 +1,46 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Landlock LSM - Credential hooks + * + * Copyright © 2017-2020 Mickaël Salaün + * Copyright © 2018-2020 ANSSI + */ + +#include +#include + +#include "common.h" +#include "cred.h" +#include "ruleset.h" +#include "setup.h" + +static int hook_cred_prepare(struct cred *const new, + const struct cred *const old, const gfp_t gfp) +{ + const struct landlock_cred_security *cred_old = landlock_cred(old); + struct landlock_cred_security *cred_new = landlock_cred(new); + struct landlock_ruleset *dom_old; + + dom_old = cred_old->domain; + if (dom_old) { + landlock_get_ruleset(dom_old); + cred_new->domain = dom_old; + } + return 0; +} + +static void hook_cred_free(struct cred *const cred) +{ + landlock_put_ruleset_deferred(landlock_cred(cred)->domain); +} + +static struct security_hook_list landlock_hooks[] __lsm_ro_after_init = { + LSM_HOOK_INIT(cred_prepare, hook_cred_prepare), + LSM_HOOK_INIT(cred_free, hook_cred_free), +}; + +__init void landlock_add_hooks_cred(void) +{ + security_add_hooks(landlock_hooks, ARRAY_SIZE(landlock_hooks), + LANDLOCK_NAME); +} diff --git a/security/landlock/cred.h b/security/landlock/cred.h new file mode 100644 index 000000000000..2983dd4dda46 --- /dev/null +++ b/security/landlock/cred.h @@ -0,0 +1,58 @@ +/* SPDX-License-Identifier: GPL-2.0-only */ +/* + * Landlock LSM - Credential hooks + * + * Copyright © 2019 Mickaël Salaün + * Copyright © 2019 ANSSI + */ + +#ifndef _SECURITY_LANDLOCK_CRED_H +#define _SECURITY_LANDLOCK_CRED_H + +#include +#include +#include + +#include "ruleset.h" +#include "setup.h" + +struct landlock_cred_security { + struct landlock_ruleset *domain; +}; + +static inline struct landlock_cred_security *landlock_cred( + const struct cred *cred) +{ + return cred->security + landlock_blob_sizes.lbs_cred; +} + +static inline const struct landlock_ruleset *landlock_get_current_domain(void) +{ + return landlock_cred(current_cred())->domain; +} + +/* + * The call needs to come from an RCU read-side critical section. + */ +static inline const struct landlock_ruleset *landlock_get_task_domain( + const struct task_struct *const task) +{ + return landlock_cred(__task_cred(task))->domain; +} + +static inline bool landlocked(const struct task_struct *const task) +{ + bool has_dom; + + if (task == current) + return !!landlock_get_current_domain(); + + rcu_read_lock(); + has_dom = !!landlock_get_task_domain(task); + rcu_read_unlock(); + return has_dom; +} + +__init void landlock_add_hooks_cred(void); + +#endif /* _SECURITY_LANDLOCK_CRED_H */ diff --git a/security/landlock/setup.c b/security/landlock/setup.c new file mode 100644 index 000000000000..39ee1766f175 --- /dev/null +++ b/security/landlock/setup.c @@ -0,0 +1,31 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Landlock LSM - Security framework setup + * + * Copyright © 2016-2020 Mickaël Salaün + * Copyright © 2018-2020 ANSSI + */ + +#include +#include + +#include "common.h" +#include "cred.h" +#include "setup.h" + +struct lsm_blob_sizes landlock_blob_sizes __lsm_ro_after_init = { + .lbs_cred = sizeof(struct landlock_cred_security), +}; + +static int __init landlock_init(void) +{ + landlock_add_hooks_cred(); + pr_info("Up and running.\n"); + return 0; +} + +DEFINE_LSM(LANDLOCK_NAME) = { + .name = LANDLOCK_NAME, + .init = landlock_init, + .blobs = &landlock_blob_sizes, +}; diff --git a/security/landlock/setup.h b/security/landlock/setup.h new file mode 100644 index 000000000000..9fdbf33fcc33 --- /dev/null +++ b/security/landlock/setup.h @@ -0,0 +1,16 @@ +/* SPDX-License-Identifier: GPL-2.0-only */ +/* + * Landlock LSM - Security framework setup + * + * Copyright © 2016-2020 Mickaël Salaün + * Copyright © 2018-2020 ANSSI + */ + +#ifndef _SECURITY_LANDLOCK_SETUP_H +#define _SECURITY_LANDLOCK_SETUP_H + +#include + +extern struct lsm_blob_sizes landlock_blob_sizes; + +#endif /* _SECURITY_LANDLOCK_SETUP_H */