Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752778AbdLHEY2 (ORCPT ); Thu, 7 Dec 2017 23:24:28 -0500 Received: from mail-it0-f67.google.com ([209.85.214.67]:34672 "EHLO mail-it0-f67.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752632AbdLHEYZ (ORCPT ); Thu, 7 Dec 2017 23:24:25 -0500 X-Google-Smtp-Source: AGs4zMZOnAAuQQFXDkoxnsFQMfVmWpJJclxrsYFC710cgeygRcIbX+Nc1w4hAVEIIjJvItmIUDwCNA== From: Sargun Dhillon X-Google-Original-From: Sargun Dhillon Date: Fri, 8 Dec 2017 04:24:23 +0000 To: linux-security-module@vger.kernel.org Cc: keescook@chromium.org, igor.stoppa@huawei.com, casey@schaufler-ca.com, linux-kernel@vger.kernel.org Subject: [RFC v2 3/3] LSM: Add an example sample dynamic LSM Message-ID: References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.24 (2015-08-30) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3000 Lines: 100 This adds an example LSM that utilizes the features added by the dynamically loadable LSMs patch. Once the module is unloaded, the command is once again allowed. It prevents the user from running: date --set="October 21 2015 16:29:00 PDT The behaviour can be verified by looking at: /sys/kernel/security/dynamic_hooks/settime Signed-off-by: Sargun Dhillon --- samples/Kconfig | 6 ++++++ samples/Makefile | 2 +- samples/lsm/Makefile | 4 ++++ samples/lsm/lsm_example.c | 39 +++++++++++++++++++++++++++++++++++++++ 4 files changed, 50 insertions(+), 1 deletion(-) create mode 100644 samples/lsm/Makefile create mode 100644 samples/lsm/lsm_example.c diff --git a/samples/Kconfig b/samples/Kconfig index c332a3b9de05..283f44252ca4 100644 --- a/samples/Kconfig +++ b/samples/Kconfig @@ -117,4 +117,10 @@ config SAMPLE_STATX help Build example userspace program to use the new extended-stat syscall. +config SAMPLE_DYNAMIC_LSM + tristate "Build LSM examples -- loadable modules only" + depends on SECURITY_DYNAMIC_HOOKS_FS && m + help + This builds an example dynamic LSM + endif # SAMPLES diff --git a/samples/Makefile b/samples/Makefile index db54e766ddb1..9d23835d6e6d 100644 --- a/samples/Makefile +++ b/samples/Makefile @@ -3,4 +3,4 @@ obj-$(CONFIG_SAMPLES) += kobject/ kprobes/ trace_events/ livepatch/ \ hw_breakpoint/ kfifo/ kdb/ hidraw/ rpmsg/ seccomp/ \ configfs/ connector/ v4l/ trace_printk/ blackfin/ \ - vfio-mdev/ statx/ + vfio-mdev/ statx/ lsm/ diff --git a/samples/lsm/Makefile b/samples/lsm/Makefile new file mode 100644 index 000000000000..d4ccb940f18b --- /dev/null +++ b/samples/lsm/Makefile @@ -0,0 +1,4 @@ +# builds the loadable LSM example kernel modules; +# then to use one (as root): insmod +# and to unload: rmmod module_name +obj-$(CONFIG_SAMPLE_DYNAMIC_LSM) += lsm_example.o diff --git a/samples/lsm/lsm_example.c b/samples/lsm/lsm_example.c new file mode 100644 index 000000000000..7c36ca231e77 --- /dev/null +++ b/samples/lsm/lsm_example.c @@ -0,0 +1,39 @@ +/* + * This sample hooks into the "path_chroot" + * + * Once you run it, the following will not be allowed: + * date --set="October 21 2015 16:29:00 PDT" + */ + +#include +#include +#include + +static const char lsm_name[] = "example"; + +static int settime_cb(const struct timespec *ts, const struct timezone *tz) +{ + /* We aren't allowed to travel to October 21 2015 16:29 PDT */ + if (ts->tv_sec >= 1445470140 && ts->tv_sec < 1445470200) + return -EPERM; + + return 0; +} + +DYNAMIC_SECURITY_HOOK(my_hook, lsm_name, settime, settime_cb); + +static int __init lsm_init(void) +{ + int ret; + + ret = security_add_dynamic_hook(&my_hook); + if (!ret) + pr_info("Successfully installed example dynamic LSM\n"); + else + pr_err("Unable to install dynamic LSM - %d\n", ret); + + return ret; +} + +module_init(lsm_init) +MODULE_LICENSE("GPL"); -- 2.14.1