selftests/timens: Add Time Namespace test for supported clocks

A test to check that all supported clocks work on host and inside
a new time namespace. Use both ways to get time: through VDSO and
by entering the kernel with implicit syscall.

Introduce a new timens directory in selftests framework for
the next timens tests.

Output on success:
 1..10
 ok 1 Passed for CLOCK_BOOTTIME (syscall)
 ok 2 Passed for CLOCK_BOOTTIME (vdso)
 ok 3 Passed for CLOCK_BOOTTIME_ALARM (syscall)
 ok 4 Passed for CLOCK_BOOTTIME_ALARM (vdso)
 ok 5 Passed for CLOCK_MONOTONIC (syscall)
 ok 6 Passed for CLOCK_MONOTONIC (vdso)
 ok 7 Passed for CLOCK_MONOTONIC_COARSE (syscall)
 ok 8 Passed for CLOCK_MONOTONIC_COARSE (vdso)
 ok 9 Passed for CLOCK_MONOTONIC_RAW (syscall)
 ok 10 Passed for CLOCK_MONOTONIC_RAW (vdso)
 # Pass 10 Fail 0 Xfail 0 Xpass 0 Skip 0 Error 0

Output with lack of permissions:
 1..10
 not ok 1 # SKIP need to run as root

Output without support of time namespaces:
 1..10
 not ok 1 # SKIP Time namespaces are not supported

Co-developed-by: Andrei Vagin <avagin@openvz.org>
Signed-off-by: Andrei Vagin <avagin@gmail.com>
Signed-off-by: Dmitry Safonov <dima@arista.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20191112012724.250792-29-dima@arista.com

1 files changed, 190 insertions, 0 deletions

diff --git a/tools/testing/selftests/timens/timens.c b/tools/testing/selftests/timens/timens.c
new file mode 100644
index 000000000000..559d26e21ba0
--- /dev/null
+++ b/tools/testing/selftests/timens/timens.c
@@ -0,0 +1,190 @@
+// SPDX-License-Identifier: GPL-2.0
+#define _GNU_SOURCE
+#include <errno.h>
+#include <fcntl.h>
+#include <sched.h>
+#include <stdio.h>
+#include <stdbool.h>
+#include <sys/stat.h>
+#include <sys/syscall.h>
+#include <sys/types.h>
+#include <time.h>
+#include <unistd.h>
+#include <time.h>
+#include <string.h>
+
+#include "log.h"
+#include "timens.h"
+
+/*
+ * Test shouldn't be run for a day, so add 10 days to child
+ * time and check parent's time to be in the same day.
+ */
+#define DAY_IN_SEC			(60*60*24)
+#define TEN_DAYS_IN_SEC			(10*DAY_IN_SEC)
+
+#define ARRAY_SIZE(arr) (sizeof(arr) / sizeof((arr)[0]))
+
+struct test_clock {
+	clockid_t id;
+	char *name;
+	/*
+	 * off_id is -1 if a clock has own offset, or it contains an index
+	 * which contains a right offset of this clock.
+	 */
+	int off_id;
+	time_t offset;
+};
+
+#define ct(clock, off_id)	{ clock, #clock, off_id }
+static struct test_clock clocks[] = {
+	ct(CLOCK_BOOTTIME, -1),
+	ct(CLOCK_BOOTTIME_ALARM, 1),
+	ct(CLOCK_MONOTONIC, -1),
+	ct(CLOCK_MONOTONIC_COARSE, 1),
+	ct(CLOCK_MONOTONIC_RAW, 1),
+};
+#undef ct
+
+static int child_ns, parent_ns = -1;
+
+static int switch_ns(int fd)
+{
+	if (setns(fd, CLONE_NEWTIME)) {
+		pr_perror("setns()");
+		return -1;
+	}
+
+	return 0;
+}
+
+static int init_namespaces(void)
+{
+	char path[] = "/proc/self/ns/time_for_children";
+	struct stat st1, st2;
+
+	if (parent_ns == -1) {
+		parent_ns = open(path, O_RDONLY);
+		if (parent_ns <= 0)
+			return pr_perror("Unable to open %s", path);
+	}
+
+	if (fstat(parent_ns, &st1))
+		return pr_perror("Unable to stat the parent timens");
+
+	if (unshare_timens())
+		return  -1;
+
+	child_ns = open(path, O_RDONLY);
+	if (child_ns <= 0)
+		return pr_perror("Unable to open %s", path);
+
+	if (fstat(child_ns, &st2))
+		return pr_perror("Unable to stat the timens");
+
+	if (st1.st_ino == st2.st_ino)
+		return pr_perror("The same child_ns after CLONE_NEWTIME");
+
+	return 0;
+}
+
+static int test_gettime(clockid_t clock_index, bool raw_syscall, time_t offset)
+{
+	struct timespec child_ts_new, parent_ts_old, cur_ts;
+	char *entry = raw_syscall ? "syscall" : "vdso";
+	double precision = 0.0;
+
+	if (check_skip(clocks[clock_index].id))
+		return 0;
+
+	switch (clocks[clock_index].id) {
+	case CLOCK_MONOTONIC_COARSE:
+	case CLOCK_MONOTONIC_RAW:
+		precision = -2.0;
+		break;
+	}
+
+	if (switch_ns(parent_ns))
+		return pr_err("switch_ns(%d)", child_ns);
+
+	if (_gettime(clocks[clock_index].id, &parent_ts_old, raw_syscall))
+		return -1;
+
+	child_ts_new.tv_nsec = parent_ts_old.tv_nsec;
+	child_ts_new.tv_sec = parent_ts_old.tv_sec + offset;
+
+	if (switch_ns(child_ns))
+		return pr_err("switch_ns(%d)", child_ns);
+
+	if (_gettime(clocks[clock_index].id, &cur_ts, raw_syscall))
+		return -1;
+
+	if (difftime(cur_ts.tv_sec, child_ts_new.tv_sec) < precision) {
+		ksft_test_result_fail(
+			"Child's %s (%s) time has not changed: %lu -> %lu [%lu]\n",
+			clocks[clock_index].name, entry, parent_ts_old.tv_sec,
+			child_ts_new.tv_sec, cur_ts.tv_sec);
+		return -1;
+	}
+
+	if (switch_ns(parent_ns))
+		return pr_err("switch_ns(%d)", parent_ns);
+
+	if (_gettime(clocks[clock_index].id, &cur_ts, raw_syscall))
+		return -1;
+
+	if (difftime(cur_ts.tv_sec, parent_ts_old.tv_sec) > DAY_IN_SEC) {
+		ksft_test_result_fail(
+			"Parent's %s (%s) time has changed: %lu -> %lu [%lu]\n",
+			clocks[clock_index].name, entry, parent_ts_old.tv_sec,
+			child_ts_new.tv_sec, cur_ts.tv_sec);
+		/* Let's play nice and put it closer to original */
+		clock_settime(clocks[clock_index].id, &cur_ts);
+		return -1;
+	}
+
+	ksft_test_result_pass("Passed for %s (%s)\n",
+				clocks[clock_index].name, entry);
+	return 0;
+}
+
+int main(int argc, char *argv[])
+{
+	unsigned int i;
+	time_t offset;
+	int ret = 0;
+
+	nscheck();
+
+	check_config_posix_timers();
+
+	ksft_set_plan(ARRAY_SIZE(clocks) * 2);
+
+	if (init_namespaces())
+		return 1;
+
+	/* Offsets have to be set before tasks enter the namespace. */
+	for (i = 0; i < ARRAY_SIZE(clocks); i++) {
+		if (clocks[i].off_id != -1)
+			continue;
+		offset = TEN_DAYS_IN_SEC + i * 1000;
+		clocks[i].offset = offset;
+		if (_settime(clocks[i].id, offset))
+			return 1;
+	}
+
+	for (i = 0; i < ARRAY_SIZE(clocks); i++) {
+		if (clocks[i].off_id != -1)
+			offset = clocks[clocks[i].off_id].offset;
+		else
+			offset = clocks[i].offset;
+		ret |= test_gettime(i, true, offset);
+		ret |= test_gettime(i, false, offset);
+	}
+
+	if (ret)
+		ksft_exit_fail();
+
+	ksft_exit_pass();
+	return !!ret;
+}