1 files changed, 294 insertions, 0 deletions
diff --git a/crypto/jitterentropy-testing.c b/crypto/jitterentropy-testing.c
new file mode 100644
index 0000000000000..5cb6a77b8e3b2
--- /dev/null
+++ b/crypto/jitterentropy-testing.c
@@ -0,0 +1,294 @@
+/* SPDX-License-Identifier: GPL-2.0 OR BSD-2-Clause */
+/*
+ * Test interface for Jitter RNG.
+ *
+ * Copyright (C) 2023, Stephan Mueller <smueller@chronox.de>
+ */
+
+#include <linux/debugfs.h>
+#include <linux/module.h>
+#include <linux/uaccess.h>
+
+#include "jitterentropy.h"
+
+#define JENT_TEST_RINGBUFFER_SIZE	(1<<10)
+#define JENT_TEST_RINGBUFFER_MASK	(JENT_TEST_RINGBUFFER_SIZE - 1)
+
+struct jent_testing {
+	u32 jent_testing_rb[JENT_TEST_RINGBUFFER_SIZE];
+	u32 rb_reader;
+	atomic_t rb_writer;
+	atomic_t jent_testing_enabled;
+	spinlock_t lock;
+	wait_queue_head_t read_wait;
+};
+
+static struct dentry *jent_raw_debugfs_root = NULL;
+
+/*************************** Generic Data Handling ****************************/
+
+/*
+ * boot variable:
+ * 0 ==> No boot test, gathering of runtime data allowed
+ * 1 ==> Boot test enabled and ready for collecting data, gathering runtime
+ *	 data is disabled
+ * 2 ==> Boot test completed and disabled, gathering of runtime data is
+ *	 disabled
+ */
+
+static void jent_testing_reset(struct jent_testing *data)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&data->lock, flags);
+	data->rb_reader = 0;
+	atomic_set(&data->rb_writer, 0);
+	spin_unlock_irqrestore(&data->lock, flags);
+}
+
+static void jent_testing_data_init(struct jent_testing *data, u32 boot)
+{
+	/*
+	 * 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)
+		return;
+
+	jent_testing_reset(data);
+	atomic_set(&data->jent_testing_enabled, 1);
+	pr_warn("Enabling data collection\n");
+}
+
+static void jent_testing_fini(struct jent_testing *data, u32 boot)
+{
+	/* If we have boot data, we do not reset yet to allow data to be read */
+	if (boot)
+		return;
+
+	atomic_set(&data->jent_testing_enabled, 0);
+	jent_testing_reset(data);
+	pr_warn("Disabling data collection\n");
+}
+
+static bool jent_testing_store(struct jent_testing *data, u32 value,
+			       u32 *boot)
+{
+	unsigned long flags;
+
+	if (!atomic_read(&data->jent_testing_enabled) && (*boot != 1))
+		return false;
+
+	spin_lock_irqsave(&data->lock, flags);
+
+	/*
+	 * Disable entropy testing for boot time testing after ring buffer
+	 * is filled.
+	 */
+	if (*boot) {
+		if (((u32)atomic_read(&data->rb_writer)) >
+		     JENT_TEST_RINGBUFFER_SIZE) {
+			*boot = 2;
+			pr_warn_once("One time data collection test disabled\n");
+			spin_unlock_irqrestore(&data->lock, flags);
+			return false;
+		}
+
+		if (atomic_read(&data->rb_writer) == 1)
+			pr_warn("One time data collection test enabled\n");
+	}
+
+	data->jent_testing_rb[((u32)atomic_read(&data->rb_writer)) &
+			      JENT_TEST_RINGBUFFER_MASK] = value;
+	atomic_inc(&data->rb_writer);
+
+	spin_unlock_irqrestore(&data->lock, flags);
+
+	if (wq_has_sleeper(&data->read_wait))
+		wake_up_interruptible(&data->read_wait);
+
+	return true;
+}
+
+static bool jent_testing_have_data(struct jent_testing *data)
+{
+	return ((((u32)atomic_read(&data->rb_writer)) &
+		 JENT_TEST_RINGBUFFER_MASK) !=
+		 (data->rb_reader & JENT_TEST_RINGBUFFER_MASK));
+}
+
+static int jent_testing_reader(struct jent_testing *data, u32 *boot,
+			       u8 *outbuf, u32 outbuflen)
+{
+	unsigned long flags;
+	int collected_data = 0;
+
+	jent_testing_data_init(data, *boot);
+
+	while (outbuflen) {
+		u32 writer = (u32)atomic_read(&data->rb_writer);
+
+		spin_lock_irqsave(&data->lock, flags);
+
+		/* We have no data or reached the writer. */
+		if (!writer || (writer == data->rb_reader)) {
+
+			spin_unlock_irqrestore(&data->lock, flags);
+
+			/*
+			 * Now we gathered all boot data, enable regular data
+			 * collection.
+			 */
+			if (*boot) {
+				*boot = 0;
+				goto out;
+			}
+
+			wait_event_interruptible(data->read_wait,
+						 jent_testing_have_data(data));
+			if (signal_pending(current)) {
+				collected_data = -ERESTARTSYS;
+				goto out;
+			}
+
+			continue;
+		}
+
+		/* We copy out word-wise */
+		if (outbuflen < sizeof(u32)) {
+			spin_unlock_irqrestore(&data->lock, flags);
+			goto out;
+		}
+
+		memcpy(outbuf, &data->jent_testing_rb[data->rb_reader],
+		       sizeof(u32));
+		data->rb_reader++;
+
+		spin_unlock_irqrestore(&data->lock, flags);
+
+		outbuf += sizeof(u32);
+		outbuflen -= sizeof(u32);
+		collected_data += sizeof(u32);
+	}
+
+out:
+	jent_testing_fini(data, *boot);
+	return collected_data;
+}
+
+static int jent_testing_extract_user(struct file *file, char __user *buf,
+				     size_t nbytes, loff_t *ppos,
+				     int (*reader)(u8 *outbuf, u32 outbuflen))
+{
+	u8 *tmp, *tmp_aligned;
+	int ret = 0, large_request = (nbytes > 256);
+
+	if (!nbytes)
+		return 0;
+
+	/*
+	 * The intention of this interface is for collecting at least
+	 * 1000 samples due to the SP800-90B requirements. So, we make no
+	 * effort in avoiding allocating more memory that actually needed
+	 * by the user. Hence, we allocate sufficient memory to always hold
+	 * that amount of data.
+	 */
+	tmp = kmalloc(JENT_TEST_RINGBUFFER_SIZE + sizeof(u32), GFP_KERNEL);
+	if (!tmp)
+		return -ENOMEM;
+
+	tmp_aligned = PTR_ALIGN(tmp, sizeof(u32));
+
+	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, JENT_TEST_RINGBUFFER_SIZE);
+		i = reader(tmp_aligned, i);
+		if (i <= 0) {
+			if (i < 0)
+				ret = i;
+			break;
+		}
+		if (copy_to_user(buf, tmp_aligned, i)) {
+			ret = -EFAULT;
+			break;
+		}
+
+		nbytes -= i;
+		buf += i;
+		ret += i;
+	}
+
+	kfree_sensitive(tmp);
+
+	if (ret > 0)
+		*ppos += ret;
+
+	return ret;
+}
+
+/************** Raw High-Resolution Timer Entropy Data Handling **************/
+
+static u32 boot_raw_hires_test = 0;
+module_param(boot_raw_hires_test, uint, 0644);
+MODULE_PARM_DESC(boot_raw_hires_test,
+		 "Enable gathering boot time high resolution timer entropy of the first Jitter RNG entropy events");
+
+static struct jent_testing jent_raw_hires = {
+	.rb_reader = 0,
+	.rb_writer = ATOMIC_INIT(0),
+	.lock      = __SPIN_LOCK_UNLOCKED(jent_raw_hires.lock),
+	.read_wait = __WAIT_QUEUE_HEAD_INITIALIZER(jent_raw_hires.read_wait)
+};
+
+int jent_raw_hires_entropy_store(__u32 value)
+{
+	return jent_testing_store(&jent_raw_hires, value, &boot_raw_hires_test);
+}
+EXPORT_SYMBOL(jent_raw_hires_entropy_store);
+
+static int jent_raw_hires_entropy_reader(u8 *outbuf, u32 outbuflen)
+{
+	return jent_testing_reader(&jent_raw_hires, &boot_raw_hires_test,
+				   outbuf, outbuflen);
+}
+
+static ssize_t jent_raw_hires_read(struct file *file, char __user *to,
+				   size_t count, loff_t *ppos)
+{
+	return jent_testing_extract_user(file, to, count, ppos,
+					 jent_raw_hires_entropy_reader);
+}
+
+static const struct file_operations jent_raw_hires_fops = {
+	.owner = THIS_MODULE,
+	.read = jent_raw_hires_read,
+};
+
+/******************************* Initialization *******************************/
+
+void jent_testing_init(void)
+{
+	jent_raw_debugfs_root = debugfs_create_dir(KBUILD_MODNAME, NULL);
+
+	debugfs_create_file_unsafe("jent_raw_hires", 0400,
+				   jent_raw_debugfs_root, NULL,
+				   &jent_raw_hires_fops);
+}
+EXPORT_SYMBOL(jent_testing_init);
+
+void jent_testing_exit(void)
+{
+	debugfs_remove_recursive(jent_raw_debugfs_root);
+}
+EXPORT_SYMBOL(jent_testing_exit);