[v5,5/5] sidechannel: Linux Security Module for sidechannel

Message ID	20180926203446.2004-6-casey.schaufler@intel.com (mailing list archive)
State	New, archived
Headers	show Return-Path: <linux-security-module-owner@kernel.org> From: Casey Schaufler <casey.schaufler@intel.com> To: kernel-hardening@lists.openwall.com, linux-kernel@vger.kernel.org, linux-security-module@vger.kernel.org, selinux@tycho.nsa.gov, casey.schaufler@intel.com, dave.hansen@intel.com, deneen.t.dock@intel.com, kristen@linux.intel.com, arjan@linux.intel.com Subject: [PATCH v5 5/5] sidechannel: Linux Security Module for sidechannel Date: Wed, 26 Sep 2018 13:34:46 -0700 Message-Id: <20180926203446.2004-6-casey.schaufler@intel.com> In-Reply-To: <20180926203446.2004-1-casey.schaufler@intel.com> References: <20180926203446.2004-1-casey.schaufler@intel.com> Sender: owner-linux-security-module@vger.kernel.org Precedence: bulk
Series	LSM: Support ptrace sidechannel access checks \| expand [v5,0/5] LSM: Support ptrace sidechannel access checks [v5,1/5] AppArmor: Prepare for PTRACE_MODE_SCHED [v5,2/5] Smack: Prepare for PTRACE_MODE_SCHED [v5,3/5] SELinux: Prepare for PTRACE_MODE_SCHED [v5,4/5] Capability: Complete PTRACE_MODE_SCHED [v5,5/5] sidechannel: Linux Security Module for sidechannel

diff --git a/include/linux/lsm_hooks.h b/include/linux/lsm_hooks.h index 97a020c616ad..3cb6516dba3c 100644 --- a/include/linux/lsm_hooks.h +++ b/include/linux/lsm_hooks.h @@ -2081,5 +2081,10 @@ void __init loadpin_add_hooks(void); #else static inline void loadpin_add_hooks(void) { }; #endif +#ifdef CONFIG_SECURITY_SIDECHANNEL +void __init sidechannel_add_hooks(void); +#else +static inline void sidechannel_add_hooks(void) { }; +#endif #endif /* ! __LINUX_LSM_HOOKS_H */ diff --git a/security/Kconfig b/security/Kconfig index d9aa521b5206..6b814a3f93ea 100644 --- a/security/Kconfig +++ b/security/Kconfig @@ -236,6 +236,7 @@ source security/tomoyo/Kconfig source security/apparmor/Kconfig source security/loadpin/Kconfig source security/yama/Kconfig +source security/sidechannel/Kconfig source security/integrity/Kconfig diff --git a/security/Makefile b/security/Makefile index 4d2d3782ddef..d0c9e1b227f9 100644 --- a/security/Makefile +++ b/security/Makefile @@ -10,6 +10,7 @@ subdir-$(CONFIG_SECURITY_TOMOYO) += tomoyo subdir-$(CONFIG_SECURITY_APPARMOR) += apparmor subdir-$(CONFIG_SECURITY_YAMA) += yama subdir-$(CONFIG_SECURITY_LOADPIN) += loadpin +subdir-$(CONFIG_SECURITY_SIDECHANNEL) += sidechannel # always enable default capabilities obj-y += commoncap.o @@ -25,6 +26,7 @@ obj-$(CONFIG_SECURITY_TOMOYO) += tomoyo/ obj-$(CONFIG_SECURITY_APPARMOR) += apparmor/ obj-$(CONFIG_SECURITY_YAMA) += yama/ obj-$(CONFIG_SECURITY_LOADPIN) += loadpin/ +obj-$(CONFIG_SECURITY_SIDECHANNEL) += sidechannel/ obj-$(CONFIG_CGROUP_DEVICE) += device_cgroup.o # Object integrity file lists diff --git a/security/security.c b/security/security.c index 736e78da1ab9..2129b0e31d7b 100644 --- a/security/security.c +++ b/security/security.c @@ -83,6 +83,7 @@ int __init security_init(void) capability_add_hooks(); yama_add_hooks(); loadpin_add_hooks(); + sidechannel_add_hooks(); /* * Load all the remaining security modules. diff --git a/security/sidechannel/Kconfig b/security/sidechannel/Kconfig new file mode 100644 index 000000000000..653033027415 --- /dev/null +++ b/security/sidechannel/Kconfig @@ -0,0 +1,13 @@ +config SECURITY_SIDECHANNEL + bool "Sidechannel attack safety extra checks" + depends on SECURITY + default n + help + Look for a variety of cases where a side-channel attack + could potentially be exploited. Instruct the switching + code to use the indirect_branch_prediction_barrier in + cases where the passed task and the current task may be + at risk. + + If you are unsure how to answer this question, answer N. + diff --git a/security/sidechannel/Makefile b/security/sidechannel/Makefile new file mode 100644 index 000000000000..f61d83f28035 --- /dev/null +++ b/security/sidechannel/Makefile @@ -0,0 +1 @@ +obj-$(CONFIG_SECURITY_SIDECHANNEL) += sidechannel.o diff --git a/security/sidechannel/sidechannel.c b/security/sidechannel/sidechannel.c new file mode 100644 index 000000000000..18a67d19c020 --- /dev/null +++ b/security/sidechannel/sidechannel.c @@ -0,0 +1,88 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +/* + * Side Channel Safety Security Module + * + * Copyright (C) 2018 Intel Corporation. + * + */ + +#define pr_fmt(fmt) "SideChannel: " fmt + +#include <linux/types.h> +#include <linux/lsm_hooks.h> +#include <linux/capability.h> +#include <linux/cred.h> +#include <linux/sched.h> +#include <linux/string_helpers.h> +#include <linux/nsproxy.h> +#include <linux/pid_namespace.h> +#include <linux/ptrace.h> + +#ifdef CONFIG_NAMESPACES +/** + * safe_by_namespace - Are task and current sidechannel safe? + * @p: task to check on + * + * Returns 0 if the tasks are sidechannel safe, -EACCES otherwise. + */ +static int safe_by_namespace(struct task_struct *p) +{ + struct cgroup_namespace *ccgn = NULL; + struct cgroup_namespace *pcgn = NULL; + + /* + * Namespace checks. Considered safe if: + * cgroup namespace is the same + * User namespace is the same + * PID namespace is the same + */ + if (current->nsproxy) + ccgn = current->nsproxy->cgroup_ns; + if (p->nsproxy) + pcgn = p->nsproxy->cgroup_ns; + if (ccgn != pcgn) + return -EACCES; + if (current->cred->user_ns != p->cred->user_ns) + return -EACCES; + if (task_active_pid_ns(current) != task_active_pid_ns(p)) + return -EACCES; + return 0; +} +#else +static int safe_by_namespace(struct task_struct *p) +{ + return 0; +} +#endif + +/** + * sidechannel_ptrace_access_check - Are task and current sidechannel safe? + * @p: task to check on + * @mode: ptrace access mode + * + * Returns 0 if the tasks are sidechannel safe, -EACCES otherwise. + */ +static int sidechannel_ptrace_access_check(struct task_struct *p, + unsigned int mode) +{ + int rc; + + if ((mode & PTRACE_MODE_SCHED) == 0) + return 0; + + rc = safe_by_namespace(p); + if (rc) + return rc; + return 0; +} + +static struct security_hook_list sidechannel_hooks[] __lsm_ro_after_init = { + LSM_HOOK_INIT(ptrace_access_check, sidechannel_ptrace_access_check), +}; + +void __init sidechannel_add_hooks(void) +{ + pr_info("Extra sidechannel checks enabled\n"); + security_add_hooks(sidechannel_hooks, ARRAY_SIZE(sidechannel_hooks), + "sidechannel"); +}

[v5,5/5] sidechannel: Linux Security Module for sidechannel

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