The test interface allows a privileged process to capture the raw
unconditioned noise that is collected by the LRNG for statistical
analysis. Extracted noise data is not used to seed the LRNG. This
is a test interface and not appropriate for production systems.
Yet, the interface is considered to be sufficiently secured for
production systems.
Access to the data is given through the lrng_raw debugfs file. The
data buffer should be multiples of sizeof(u32) to fill the entire
buffer. Using the option lrng_testing.boot_test=1 the raw noise of
the first 1000 entropy events since boot can be sampled.
This test interface allows generating the data required for
analysis whether the LRNG is in compliance with SP800-90B
sections 3.1.3 and 3.1.4.
CC: "Eric W. Biederman" <[email protected]>
CC: "Alexander E. Patrakov" <[email protected]>
CC: "Ahmed S. Darwish" <[email protected]>
CC: "Theodore Y. Ts'o" <[email protected]>
CC: Willy Tarreau <[email protected]>
CC: Matthew Garrett <[email protected]>
CC: Vito Caputo <[email protected]>
CC: Andreas Dilger <[email protected]>
CC: Jan Kara <[email protected]>
CC: Ray Strode <[email protected]>
CC: William Jon McCann <[email protected]>
CC: zhangjs <[email protected]>
CC: Andy Lutomirski <[email protected]>
CC: Florian Weimer <[email protected]>
CC: Lennart Poettering <[email protected]>
CC: Nicolai Stange <[email protected]>
Reviewed-by: Roman Drahtmueller <[email protected]>
Tested-by: Roman Drahtm?ller <[email protected]>
Tested-by: Marcelo Henrique Cerri <[email protected]>
Tested-by: Neil Horman <[email protected]>
Signed-off-by: Stephan Mueller <[email protected]>
---
drivers/char/lrng/Kconfig | 16 ++
drivers/char/lrng/Makefile | 1 +
drivers/char/lrng/lrng_testing.c | 324 +++++++++++++++++++++++++++++++
3 files changed, 341 insertions(+)
create mode 100644 drivers/char/lrng/lrng_testing.c
diff --git a/drivers/char/lrng/Kconfig b/drivers/char/lrng/Kconfig
index 4373a1a19538..c3d7524b7698 100644
--- a/drivers/char/lrng/Kconfig
+++ b/drivers/char/lrng/Kconfig
@@ -126,4 +126,20 @@ config LRNG_HEALTH_TESTS
If unsure, say Y.
+config LRNG_TESTING
+ bool "Enable entropy test interface to LRNG noise source"
+ select CONFIG_DEBUG_FS
+ help
+ The test interface allows a privileged process to capture
+ the raw unconditioned noise that is collected by the LRNG
+ for statistical analysis. Extracted noise data is not used
+ to seed the LRNG.
+
+ The raw noise data can be obtained using the lrng_raw
+ debugfs file. Using the option lrng_testing.boot_test=1
+ the raw noise of the first 1000 entropy events since boot
+ can be sampled.
+
+ If unsure, say N.
+
endif # LRNG
diff --git a/drivers/char/lrng/Makefile b/drivers/char/lrng/Makefile
index 0713e9c0aa6e..c0b6cc4301fe 100644
--- a/drivers/char/lrng/Makefile
+++ b/drivers/char/lrng/Makefile
@@ -16,3 +16,4 @@ obj-$(CONFIG_LRNG_KCAPI) += lrng_kcapi.o
obj-$(CONFIG_LRNG_JENT) += lrng_jent.o
obj-$(CONFIG_LRNG_TRNG_SUPPORT) += lrng_trng.o
obj-$(CONFIG_LRNG_HEALTH_TESTS) += lrng_health.o
+obj-$(CONFIG_LRNG_TESTING) += lrng_testing.o
diff --git a/drivers/char/lrng/lrng_testing.c b/drivers/char/lrng/lrng_testing.c
new file mode 100644
index 000000000000..584bf926c05b
--- /dev/null
+++ b/drivers/char/lrng/lrng_testing.c
@@ -0,0 +1,324 @@
+// SPDX-License-Identifier: GPL-2.0 OR BSD-2-Clause
+/*
+ * Linux Random Number Generator (LRNG) Raw entropy collection tool
+ *
+ * Copyright (C) 2019, Stephan Mueller <[email protected]>
+ *
+ * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED
+ * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+ * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE, ALL OF
+ * WHICH ARE HEREBY DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
+ * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
+ * BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
+ * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE
+ * USE OF THIS SOFTWARE, EVEN IF NOT ADVISED OF THE POSSIBILITY OF SUCH
+ * DAMAGE.
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/atomic.h>
+#include <linux/bug.h>
+#include <linux/debugfs.h>
+#include <linux/module.h>
+#include <linux/sched.h>
+#include <linux/sched/signal.h>
+#include <linux/string.h>
+#include <linux/types.h>
+#include <linux/uaccess.h>
+#include <linux/workqueue.h>
+#include <asm/errno.h>
+
+#include "lrng_internal.h"
+
+#define LRNG_TESTING_RINGBUFFER_SIZE 1024
+#define LRNG_TESTING_RINGBUFFER_MASK (LRNG_TESTING_RINGBUFFER_SIZE - 1)
+
+static u32 lrng_testing_rb[LRNG_TESTING_RINGBUFFER_SIZE];
+static atomic_t lrng_rb_reader = ATOMIC_INIT(0);
+static atomic_t lrng_rb_writer = ATOMIC_INIT(0);
+static atomic_t lrng_rb_first_in = ATOMIC_INIT(0);
+static atomic_t lrng_testing_enabled = ATOMIC_INIT(0);
+
+static DECLARE_WAIT_QUEUE_HEAD(lrng_raw_read_wait);
+
+static u32 boot_test = 0;
+module_param(boot_test, uint, 0644);
+MODULE_PARM_DESC(boot_test, "Enable gathering boot time entropy of the first"
+ " entropy events");
+
+static inline void lrng_raw_entropy_reset(void)
+{
+ atomic_set(&lrng_rb_reader, 0);
+ atomic_set(&lrng_rb_writer, 0);
+ atomic_set(&lrng_rb_first_in, 0);
+}
+
+static void lrng_raw_entropy_init(void)
+{
+ /*
+ * The boot time testing implies we have a running test. If the
+ * caller wants to clear it, he has to unset the boot_test flag
+ * at runtime via sysfs to enable regular runtime testing
+ */
+ if (boot_test)
+ return;
+
+ lrng_raw_entropy_reset();
+ atomic_set(&lrng_testing_enabled, 1);
+ pr_warn("Enabling raw entropy collection\n");
+}
+
+static void lrng_raw_entropy_fini(void)
+{
+ if (boot_test)
+ return;
+
+ lrng_raw_entropy_reset();
+ atomic_set(&lrng_testing_enabled, 0);
+ pr_warn("Disabling raw entropy collection\n");
+}
+
+bool lrng_raw_entropy_store(u32 value)
+{
+ unsigned int write_ptr;
+ unsigned int read_ptr;
+
+ if (!atomic_read(&lrng_testing_enabled) && !boot_test)
+ return false;
+
+ write_ptr = (unsigned int)atomic_add_return_relaxed(1, &lrng_rb_writer);
+ read_ptr = (unsigned int)atomic_read(&lrng_rb_reader);
+
+ /*
+ * Disable entropy testing for boot time testing after ring buffer
+ * is filled.
+ */
+ if (boot_test && write_ptr > LRNG_TESTING_RINGBUFFER_SIZE) {
+ pr_warn_once("Boot time entropy collection test disabled\n");
+ return false;
+ }
+
+ if (boot_test && !atomic_read(&lrng_rb_first_in))
+ pr_warn("Boot time entropy collection test enabled\n");
+
+ lrng_testing_rb[write_ptr & LRNG_TESTING_RINGBUFFER_MASK] = value;
+
+ /* We got at least one event, enable the reader now. */
+ atomic_set(&lrng_rb_first_in, 1);
+
+ if (wq_has_sleeper(&lrng_raw_read_wait))
+ wake_up_interruptible(&lrng_raw_read_wait);
+
+ /*
+ * Our writer is taking over the reader - this means the reader
+ * one full ring buffer available. Thus we "push" the reader ahead
+ * to guarantee that he will be able to consume the full ring.
+ */
+ if (!boot_test &&
+ ((write_ptr & LRNG_TESTING_RINGBUFFER_MASK) ==
+ (read_ptr & LRNG_TESTING_RINGBUFFER_MASK)))
+ atomic_inc_return_relaxed(&lrng_rb_reader);
+
+ return true;
+}
+
+static inline bool lrng_raw_have_data(void)
+{
+ unsigned int read_ptr = (unsigned int)atomic_read(&lrng_rb_reader);
+ unsigned int write_ptr = (unsigned int)atomic_read(&lrng_rb_writer);
+
+ return (atomic_read(&lrng_rb_first_in) &&
+ (write_ptr & LRNG_TESTING_RINGBUFFER_MASK) !=
+ (read_ptr & LRNG_TESTING_RINGBUFFER_MASK));
+}
+
+static int lrng_raw_entropy_reader(u8 *outbuf, u32 outbuflen)
+{
+ int collected_data = 0;
+
+ if (!atomic_read(&lrng_testing_enabled) && !boot_test)
+ return -EAGAIN;
+
+ if (!atomic_read(&lrng_rb_first_in)) {
+ wait_event_interruptible(lrng_raw_read_wait,
+ lrng_raw_have_data());
+ if (signal_pending(current))
+ return -ERESTARTSYS;
+ }
+
+ while (outbuflen) {
+ unsigned int read_ptr =
+ (unsigned int)atomic_add_return_relaxed(
+ 1, &lrng_rb_reader);
+ unsigned int write_ptr =
+ (unsigned int)atomic_read(&lrng_rb_writer);
+
+ /*
+ * For boot time testing, only output one round of ring buffer.
+ */
+ if (boot_test && read_ptr > LRNG_TESTING_RINGBUFFER_SIZE) {
+ collected_data = -ENOMSG;
+ goto out;
+ }
+
+ /* We reached the writer */
+ if (!boot_test && ((write_ptr & LRNG_TESTING_RINGBUFFER_MASK) ==
+ (read_ptr & LRNG_TESTING_RINGBUFFER_MASK))) {
+ wait_event_interruptible(lrng_raw_read_wait,
+ lrng_raw_have_data());
+ if (signal_pending(current))
+ return -ERESTARTSYS;
+
+ continue;
+ }
+
+ /* We copy out word-wise */
+ if (outbuflen < sizeof(u32)) {
+ atomic_dec_return_relaxed(&lrng_rb_reader);
+ goto out;
+ }
+
+ memcpy(outbuf,
+ &lrng_testing_rb[read_ptr & LRNG_TESTING_RINGBUFFER_MASK],
+ sizeof(u32));
+ outbuf += sizeof(u32);
+ outbuflen -= sizeof(u32);
+ collected_data += sizeof(u32);
+ }
+
+out:
+ return collected_data;
+}
+
+/**************************************************************************
+ * Debugfs interface
+ **************************************************************************/
+static int lrng_raw_extract_user(void __user *buf, size_t nbytes)
+{
+ u8 tmp[LRNG_TESTING_RINGBUFFER_SIZE] __aligned(sizeof(u32));
+ int ret = 0, large_request = (nbytes > 256);
+
+ while (nbytes) {
+ int i;
+
+ if (large_request && need_resched()) {
+ if (signal_pending(current)) {
+ if (ret == 0)
+ ret = -ERESTARTSYS;
+ break;
+ }
+ schedule();
+ }
+
+ i = min_t(int, nbytes, sizeof(tmp));
+ i = lrng_raw_entropy_reader(tmp, i);
+ if (i <= 0) {
+ if (i < 0)
+ ret = i;
+ break;
+ }
+ if (copy_to_user(buf, tmp, i)) {
+ ret = -EFAULT;
+ break;
+ }
+
+ nbytes -= i;
+ buf = (u8 *)buf + i;
+ ret += i;
+ }
+
+ memzero_explicit(tmp, sizeof(tmp));
+
+ return ret;
+}
+
+/*
+ * This data structure holds the dentry's of the debugfs files establishing
+ * the interface to user space.
+ */
+struct lrng_raw_debugfs {
+ struct dentry *lrng_raw_debugfs_root; /* root dentry */
+ struct dentry *lrng_raw_debugfs_lrng_raw; /* .../lrng_raw */
+};
+
+static struct lrng_raw_debugfs lrng_raw_debugfs;
+
+/* DebugFS operations and definition of the debugfs files */
+static ssize_t lrng_raw_read(struct file *file, char __user *to,
+ size_t count, loff_t *ppos)
+{
+ loff_t pos = *ppos;
+ int ret;
+
+ if (!count)
+ return 0;
+ lrng_raw_entropy_init();
+ ret = lrng_raw_extract_user(to, count);
+ lrng_raw_entropy_fini();
+ if (ret < 0)
+ return ret;
+ count -= ret;
+ *ppos = pos + count;
+ return ret;
+}
+
+/* Module init: allocate memory, register the debugfs files */
+static int lrng_raw_debugfs_init(void)
+{
+ lrng_raw_debugfs.lrng_raw_debugfs_root =
+ debugfs_create_dir(KBUILD_MODNAME, NULL);
+ if (IS_ERR(lrng_raw_debugfs.lrng_raw_debugfs_root)) {
+ lrng_raw_debugfs.lrng_raw_debugfs_root = NULL;
+ return PTR_ERR(lrng_raw_debugfs.lrng_raw_debugfs_root);
+ }
+ return 0;
+}
+
+static struct file_operations lrng_raw_name_fops = {
+ .owner = THIS_MODULE,
+ .read = lrng_raw_read,
+};
+
+static int lrng_raw_debugfs_init_name(void)
+{
+ lrng_raw_debugfs.lrng_raw_debugfs_lrng_raw =
+ debugfs_create_file("lrng_raw", 0400,
+ lrng_raw_debugfs.lrng_raw_debugfs_root,
+ NULL, &lrng_raw_name_fops);
+ if (IS_ERR(lrng_raw_debugfs.lrng_raw_debugfs_lrng_raw)) {
+ lrng_raw_debugfs.lrng_raw_debugfs_lrng_raw = NULL;
+ return PTR_ERR(lrng_raw_debugfs.lrng_raw_debugfs_lrng_raw);
+ }
+ return 0;
+}
+
+static int __init lrng_raw_init(void)
+{
+ int ret = lrng_raw_debugfs_init();
+
+ if (ret < 0)
+ return ret;
+
+ ret = lrng_raw_debugfs_init_name();
+ if (ret < 0)
+ debugfs_remove_recursive(
+ lrng_raw_debugfs.lrng_raw_debugfs_root);
+
+ return ret;
+}
+
+static void __exit lrng_raw_exit(void)
+{
+ debugfs_remove_recursive(lrng_raw_debugfs.lrng_raw_debugfs_root);
+}
+
+module_init(lrng_raw_init);
+module_exit(lrng_raw_exit);
+
+MODULE_LICENSE("Dual BSD/GPL");
+MODULE_AUTHOR("Stephan Mueller <[email protected]>");
+MODULE_DESCRIPTION("Kernel module for gathering raw entropy");
--
2.23.0
Hi "Stephan,
Thank you for the patch! Perhaps something to improve:
[auto build test WARNING on char-misc/char-misc-testing]
[also build test WARNING on v5.4-rc7 next-20191111]
[if your patch is applied to the wrong git tree, please drop us a note to help
improve the system. BTW, we also suggest to use '--base' option to specify the
base tree in git format-patch, please see https://stackoverflow.com/a/37406982]
url: https://github.com/0day-ci/linux/commits/Stephan-M-ller/dev-random-a-new-approach-with-full-SP800-90B-compliance/20191113-040847
base: https://git.kernel.org/pub/scm/linux/kernel/git/gregkh/char-misc.git 01b59c763fe2de845b65900485b141fdd7bbf93e
config: sh-allmodconfig (attached as .config)
compiler: sh4-linux-gcc (GCC) 7.4.0
reproduce:
wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
chmod +x ~/bin/make.cross
# save the attached .config to linux build tree
GCC_VERSION=7.4.0 make.cross ARCH=sh
If you fix the issue, kindly add following tag
Reported-by: kbuild test robot <[email protected]>
All warnings (new ones prefixed by >>):
drivers/char/lrng/lrng_testing.c: In function 'lrng_raw_extract_user':
>> drivers/char/lrng/lrng_testing.c:237:1: warning: the frame size of 1076 bytes is larger than 1024 bytes [-Wframe-larger-than=]
}
^
vim +237 drivers/char/lrng/lrng_testing.c
196
197 /**************************************************************************
198 * Debugfs interface
199 **************************************************************************/
200 static int lrng_raw_extract_user(void __user *buf, size_t nbytes)
201 {
202 u8 tmp[LRNG_TESTING_RINGBUFFER_SIZE] __aligned(sizeof(u32));
203 int ret = 0, large_request = (nbytes > 256);
204
205 while (nbytes) {
206 int i;
207
208 if (large_request && need_resched()) {
209 if (signal_pending(current)) {
210 if (ret == 0)
211 ret = -ERESTARTSYS;
212 break;
213 }
214 schedule();
215 }
216
217 i = min_t(int, nbytes, sizeof(tmp));
218 i = lrng_raw_entropy_reader(tmp, i);
219 if (i <= 0) {
220 if (i < 0)
221 ret = i;
222 break;
223 }
224 if (copy_to_user(buf, tmp, i)) {
225 ret = -EFAULT;
226 break;
227 }
228
229 nbytes -= i;
230 buf = (u8 *)buf + i;
231 ret += i;
232 }
233
234 memzero_explicit(tmp, sizeof(tmp));
235
236 return ret;
> 237 }
238
---
0-DAY kernel test infrastructure Open Source Technology Center
https://lists.01.org/hyperkitty/list/[email protected] Intel Corporation