[PATCH v24 03/12] LRNG - /proc interface

Stephan Müller
2019-11-11T19:14:18Z

The LRNG /proc interface provides the same files as the legacy
/dev/random. These files behave identically. Yet, all files are
documented at [1].

In addition, it provides the file lrng_type which provides details about
the LRNG:

- is the TRNG present

- the name of the DRNG that produces the random numbers for /dev/random,
/dev/urandom, getrandom(2)

- the hash used to produce random numbers from the entropy pool

- the number of secondary DRNG instances

- indicator whether the LRNG operates SP800-90B compliant

- indicator whether a high-resolution timer is identified - only with a
high-resolution timer the interrupt noise source will deliver sufficient
entropy

- indicator whether the LRNG has been minimally seeded (i.e. is the
secondary DRNG seeded with at least 128 bits of of entropy)

- indicator whether the LRNG has been fully seeded (i.e. is the
secondary DRNG seeded with at least 256 bits of entropy)

[1] https://www.chronox.de/lrng.html

CC: "Eric W. Biederman" <ebiederm@xmission.com>
CC: "Alexander E. Patrakov" <patrakov@gmail.com>
CC: "Ahmed S. Darwish" <darwish.07@gmail.com>
CC: "Theodore Y. Ts'o" <tytso@mit.edu>
CC: Willy Tarreau <w@1wt.eu>
CC: Matthew Garrett <mjg59@srcf.ucam.org>
CC: Vito Caputo <vcaputo@pengaru.com>
CC: Andreas Dilger <adilger.kernel@dilger.ca>
CC: Jan Kara <jack@suse.cz>
CC: Ray Strode <rstrode@redhat.com>
CC: William Jon McCann <mccann@jhu.edu>
CC: zhangjs <zachary@baishancloud.com>
CC: Andy Lutomirski <luto@kernel.org>
CC: Florian Weimer <fweimer@redhat.com>
CC: Lennart Poettering <mzxreary@0pointer.de>
CC: Nicolai Stange <nstange@suse.de>
Reviewed-by: Marcelo Henrique Cerri <marcelo.cerri@canonical.com>
Reviewed-by: Roman Drahtmueller <draht@schaltsekun.de>
Tested-by: Roman Drahtmüller <draht@schaltsekun.de>
Tested-by: Marcelo Henrique Cerri <marcelo.cerri@canonical.com>
Tested-by: Neil Horman <nhorman@redhat.com>
Signed-off-by: Stephan Mueller <smueller@chronox.de>
---
drivers/char/lrng/Makefile | 1 +
drivers/char/lrng/lrng_interfaces.c | 1 -
drivers/char/lrng/lrng_internal.h | 4 +
drivers/char/lrng/lrng_proc.c | 192 ++++++++++++++++++++++++++++
4 files changed, 197 insertions(+), 1 deletion(-)
create mode 100644 drivers/char/lrng/lrng_proc.c

diff --git a/drivers/char/lrng/Makefile b/drivers/char/lrng/Makefile
index a00cddb45773..b6240b73e33d 100644
--- a/drivers/char/lrng/Makefile
+++ b/drivers/char/lrng/Makefile
@@ -9,3 +9,4 @@ obj-y += lrng_pool.o lrng_aux.o \
lrng_interfaces.o \

obj-$(CONFIG_NUMA) += lrng_numa.o
+obj-$(CONFIG_SYSCTL) += lrng_proc.o
diff --git a/drivers/char/lrng/lrng_interfaces.c b/drivers/char/lrng/lrng_interfaces.c
index e652849a1bdb..1c9517c6df4a 100644
--- a/drivers/char/lrng/lrng_interfaces.c
+++ b/drivers/char/lrng/lrng_interfaces.c
@@ -56,7 +56,6 @@ static DECLARE_WAIT_QUEUE_HEAD(lrng_write_wait);
static DECLARE_WAIT_QUEUE_HEAD(lrng_init_wait);
static struct fasync_struct *fasync;

-struct ctl_table random_table[];
/********************************** Helper ***********************************/

/* Is the primary DRNG seed level too low? */
diff --git a/drivers/char/lrng/lrng_internal.h b/drivers/char/lrng/lrng_internal.h
index e6ac2c527378..8528c2e8de88 100644
--- a/drivers/char/lrng/lrng_internal.h
+++ b/drivers/char/lrng/lrng_internal.h
@@ -116,7 +116,11 @@ void lrng_cc20_init_state(struct chacha20_state *state);

/********************************** /proc *************************************/

+#ifdef CONFIG_SYSCTL
+void lrng_pool_inc_numa_node(void);
+#else
static inline void lrng_pool_inc_numa_node(void) { }
+#endif

/****************************** LRNG interfaces *******************************/

diff --git a/drivers/char/lrng/lrng_proc.c b/drivers/char/lrng/lrng_proc.c
new file mode 100644
index 000000000000..0e67dd4e5901
--- /dev/null
+++ b/drivers/char/lrng/lrng_proc.c
@@ -0,0 +1,192 @@
+// SPDX-License-Identifier: GPL-2.0 OR BSD-2-Clause
+/*
+ * LRNG proc interfaces
+ *
+ * Copyright (C) 2016 - 2019, Stephan Mueller <smueller@chronox.de>
+ *
+ * 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.
+ */
+
+#include <linux/lrng.h>
+#include <linux/sysctl.h>
+#include <linux/uuid.h>
+
+#include "lrng_internal.h"
+
+/* Number of online DRNGs */
+static u32 numa_drngs = 1;
+
+void lrng_pool_inc_numa_node(void)
+{
+ numa_drngs++;
+}
+
+/*
+ * This function is used to return both the bootid UUID, and random
+ * UUID. The difference is in whether table->data is NULL; if it is,
+ * then a new UUID is generated and returned to the user.
+ *
+ * If the user accesses this via the proc interface, the UUID will be
+ * returned as an ASCII string in the standard UUID format; if via the
+ * sysctl system call, as 16 bytes of binary data.
+ */
+static int lrng_proc_do_uuid(struct ctl_table *table, int write,
+ void __user *buffer, size_t *lenp, loff_t *ppos)
+{
+ struct ctl_table fake_table;
+ unsigned char buf[64], tmp_uuid[16], *uuid;
+
+ uuid = table->data;
+ if (!uuid) {
+ uuid = tmp_uuid;
+ generate_random_uuid(uuid);
+ } else {
+ static DEFINE_SPINLOCK(bootid_spinlock);
+
+ spin_lock(&bootid_spinlock);
+ if (!uuid[8])
+ generate_random_uuid(uuid);
+ spin_unlock(&bootid_spinlock);
+ }
+
+ sprintf(buf, "%pU", uuid);
+
+ fake_table.data = buf;
+ fake_table.maxlen = sizeof(buf);
+
+ return proc_dostring(&fake_table, write, buffer, lenp, ppos);
+}
+
+static int lrng_proc_do_type(struct ctl_table *table, int write,
+ void __user *buffer, size_t *lenp, loff_t *ppos)
+{
+ struct lrng_sdrng *lrng_sdrng_init = lrng_sdrng_init_instance();
+ struct ctl_table fake_table;
+ unsigned long flags = 0;
+ unsigned char buf[300];
+
+ lrng_sdrng_lock(lrng_sdrng_init, &flags);
+ snprintf(buf, sizeof(buf),
+#ifdef CONFIG_LRNG_TRNG_SUPPORT
+ "TRNG present: true\n"
+#else
+ "TRNG present: false\n"
+#endif
+ "DRNG name: %s\n"
+ "Hash for reading entropy pool: %s\n"
+ "DRNG security strength: %d bits\n"
+ "number of secondary DRNG instances: %u\n"
+ "SP800-90B compliance: %s\n"
+ "High-resolution timer: %s\n"
+ "LRNG minimally seeded: %s\n"
+ "LRNG fully seeded: %s",
+ lrng_sdrng_init->crypto_cb->lrng_drng_name(),
+ lrng_sdrng_init->crypto_cb->lrng_hash_name(),
+ LRNG_DRNG_SECURITY_STRENGTH_BITS, numa_drngs,
+ lrng_sp80090b_compliant() ? "true" : "false",
+ lrng_pool_highres_timer() ? "true" : "false",
+ lrng_state_min_seeded() ? "true" : "false",
+ lrng_state_fully_seeded() ? "true" : "false");
+ lrng_sdrng_unlock(lrng_sdrng_init, &flags);
+
+ fake_table.data = buf;
+ fake_table.maxlen = sizeof(buf);
+
+ return proc_dostring(&fake_table, write, buffer, lenp, ppos);
+}
+
+static int lrng_proc_do_entropy(struct ctl_table *table, int write,
+ void __user *buffer, size_t *lenp, loff_t *ppos)
+{
+ struct ctl_table fake_table;
+ int entropy_count;
+
+ entropy_count = lrng_avail_entropy();
+
+ fake_table.data = &entropy_count;
+ fake_table.maxlen = sizeof(entropy_count);
+
+ return proc_dointvec(&fake_table, write, buffer, lenp, ppos);
+}
+
+static int lrng_sysctl_poolsize = LRNG_POOL_SIZE_BITS;
+static int lrng_min_read_thresh = LRNG_POOL_WORD_BITS;
+static int lrng_min_write_thresh;
+static int lrng_max_read_thresh = LRNG_POOL_SIZE_BITS;
+static int lrng_max_write_thresh = LRNG_POOL_SIZE_BITS;
+static char lrng_sysctl_bootid[16];
+static int lrng_sdrng_reseed_max_min;
+
+extern struct ctl_table random_table[];
+struct ctl_table random_table[] = {
+ {
+ .procname = "poolsize",
+ .data = &lrng_sysctl_poolsize,
+ .maxlen = sizeof(int),
+ .mode = 0444,
+ .proc_handler = proc_dointvec,
+ },
+ {
+ .procname = "entropy_avail",
+ .maxlen = sizeof(int),
+ .mode = 0444,
+ .proc_handler = lrng_proc_do_entropy,
+ },
+ {
+ .procname = "read_wakeup_threshold",
+ .data = &lrng_read_wakeup_bits,
+ .maxlen = sizeof(int),
+ .mode = 0644,
+ .proc_handler = proc_dointvec_minmax,
+ .extra1 = &lrng_min_read_thresh,
+ .extra2 = &lrng_max_read_thresh,
+ },
+ {
+ .procname = "write_wakeup_threshold",
+ .data = &lrng_write_wakeup_bits,
+ .maxlen = sizeof(int),
+ .mode = 0644,
+ .proc_handler = proc_dointvec_minmax,
+ .extra1 = &lrng_min_write_thresh,
+ .extra2 = &lrng_max_write_thresh,
+ },
+ {
+ .procname = "boot_id",
+ .data = &lrng_sysctl_bootid,
+ .maxlen = 16,
+ .mode = 0444,
+ .proc_handler = lrng_proc_do_uuid,
+ },
+ {
+ .procname = "uuid",
+ .maxlen = 16,
+ .mode = 0444,
+ .proc_handler = lrng_proc_do_uuid,
+ },
+ {
+ .procname = "urandom_min_reseed_secs",
+ .data = &lrng_sdrng_reseed_max_time,
+ .maxlen = sizeof(int),
+ .mode = 0644,
+ .proc_handler = proc_dointvec,
+ .extra1 = &lrng_sdrng_reseed_max_min,
+ },
+ {
+ .procname = "lrng_type",
+ .maxlen = 30,
+ .mode = 0444,
+ .proc_handler = lrng_proc_do_type,
+ },
+ { }
+};
--
2.23.0