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Violators will be prosecuted for from ; Mon, 13 Nov 2017 11:43:39 -0000 Subject: [RFC PATCH v2] fw_lockdown: new micro LSM module to prevent loading unsigned firmware From: Mimi Zohar To: David Howells Cc: linux-integrity , linux-fsdevel , linux-kernel , "Luis R. Rodriguez" , "AKASHI, Takahiro" Date: Mon, 13 Nov 2017 06:43:34 -0500 Content-Type: text/plain; charset="UTF-8" Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Message-Id: <1510573414.3404.109.camel@linux.vnet.ibm.com> Sender: linux-fsdevel-owner@vger.kernel.org List-ID: If the kernel is locked down and IMA-appraisal is not enabled, prevent loading of unsigned firmware. Signed-off-by: Mimi Zohar --- Changelog v2: - Invert kernel_is_locked_down() test (Luis Rodriquez) - Increase LSM name maximum size (15 bytes + null) (Casey) Changelog v1: - Lots of minor changes Kconfig, Makefile, fw_lsm.c for such a small patch security/Kconfig | 1 + security/Makefile | 2 ++ security/fw_lockdown/Kconfig | 6 +++++ security/fw_lockdown/Makefile | 3 +++ security/fw_lockdown/fw_lsm.c | 51 +++++++++++++++++++++++++++++++++++++++++++ security/security.c | 2 +- 6 files changed, 64 insertions(+), 1 deletion(-) create mode 100644 security/fw_lockdown/Kconfig create mode 100644 security/fw_lockdown/Makefile create mode 100644 security/fw_lockdown/fw_lsm.c diff --git a/security/Kconfig b/security/Kconfig index a4fa8b826039..6e7e5888f823 100644 --- a/security/Kconfig +++ b/security/Kconfig @@ -243,6 +243,7 @@ source security/tomoyo/Kconfig source security/apparmor/Kconfig source security/loadpin/Kconfig source security/yama/Kconfig +source security/fw_lockdown/Kconfig source security/integrity/Kconfig diff --git a/security/Makefile b/security/Makefile index 8c4a43e3d4e0..58852dee5e22 100644 --- a/security/Makefile +++ b/security/Makefile @@ -9,6 +9,7 @@ subdir-$(CONFIG_SECURITY_TOMOYO) += tomoyo subdir-$(CONFIG_SECURITY_APPARMOR) += apparmor subdir-$(CONFIG_SECURITY_YAMA) += yama subdir-$(CONFIG_SECURITY_LOADPIN) += loadpin +subdir-$(CONFIG_SECURITY_FW_LOCKDOWN) += fw_lockdown # always enable default capabilities obj-y += commoncap.o @@ -24,6 +25,7 @@ obj-$(CONFIG_SECURITY_TOMOYO) += tomoyo/ obj-$(CONFIG_SECURITY_APPARMOR) += apparmor/ obj-$(CONFIG_SECURITY_YAMA) += yama/ obj-$(CONFIG_SECURITY_LOADPIN) += loadpin/ +obj-$(CONFIG_SECURITY_FW_LOCKDOWN) += fw_lockdown/ obj-$(CONFIG_CGROUP_DEVICE) += device_cgroup.o # Object integrity file lists diff --git a/security/fw_lockdown/Kconfig b/security/fw_lockdown/Kconfig new file mode 100644 index 000000000000..d6aef6ce8fee --- /dev/null +++ b/security/fw_lockdown/Kconfig @@ -0,0 +1,6 @@ +config SECURITY_FW_LOCKDOWN + bool "Prevent loading unsigned firmware" + depends on LOCK_DOWN_KERNEL + default y + help + Prevent loading unsigned firmware in lockdown mode, diff --git a/security/fw_lockdown/Makefile b/security/fw_lockdown/Makefile new file mode 100644 index 000000000000..3a16757fd35d --- /dev/null +++ b/security/fw_lockdown/Makefile @@ -0,0 +1,3 @@ +obj-$(CONFIG_SECURITY_FW_LOCKDOWN) += fw_lockdown.o + +fw_lockdown-y := fw_lsm.o diff --git a/security/fw_lockdown/fw_lsm.c b/security/fw_lockdown/fw_lsm.c new file mode 100644 index 000000000000..9a5472bc733f --- /dev/null +++ b/security/fw_lockdown/fw_lsm.c @@ -0,0 +1,51 @@ +/* + * fw_lockdown security module + * + * Copyright (C) 2017 IBM Corporation + * + * Authors: + * Mimi Zohar + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation; either version 2 of the License, or + * (at your option) any later version. + */ + +#define pr_fmt(fmt) "fw_lockdown: " fmt + +#include +#include +#include + +/** + * fw_lockdown_read_file - prevent loading of unsigned firmware + * @file: pointer to firmware + * @read_id: caller identifier + * + * Prevent loading of unsigned firmware in lockdown mode. + */ +static int fw_lockdown_read_file(struct file *file, enum kernel_read_file_id id) +{ + if (id == READING_FIRMWARE) { + if (!is_ima_appraise_enabled() && + kernel_is_locked_down("Loading of unsigned firmware")) + return -EACCES; + } + return 0; +} + +static struct security_hook_list fw_lockdown_hooks[] = { + LSM_HOOK_INIT(kernel_read_file, fw_lockdown_read_file) +}; + +static int __init init_fw_lockdown(void) +{ + security_add_hooks(fw_lockdown_hooks, ARRAY_SIZE(fw_lockdown_hooks), + "fw_lockdown"); + pr_info("initialized\n"); + return 0; +} + +late_initcall(init_fw_lockdown); +MODULE_LICENSE("GPL"); diff --git a/security/security.c b/security/security.c index 4bf0f571b4ef..61a0c95ec687 100644 --- a/security/security.c +++ b/security/security.c @@ -32,7 +32,7 @@ #define MAX_LSM_EVM_XATTR 2 /* Maximum number of letters for an LSM name string */ -#define SECURITY_NAME_MAX 10 +#define SECURITY_NAME_MAX 15 struct security_hook_heads security_hook_heads __lsm_ro_after_init; static ATOMIC_NOTIFIER_HEAD(lsm_notifier_chain); -- 2.7.4