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Date:   Thu, 13 Oct 2022 10:31:54 -0700
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Message-ID: <20221013173154.291597-1-avagin@google.com>
Subject: [PATCH 2/2 v2] selftests/timens: add a test for vfork+exit
From:   Andrei Vagin <avagin@google.com>
To:     Kees Cook <keescook@chromium.org>
Cc:     linux-kernel@vger.kernel.org, Alexey Izbyshev <izbyshev@ispras.ru>,
        Christian Brauner <brauner@kernel.org>,
        Dmitry Safonov <0x7f454c46@gmail.com>,
        "Eric W. Biederman" <ebiederm@xmission.com>,
        Florian Weimer <fweimer@redhat.com>,
        Andrei Vagin <avagin@gmail.com>
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From: Andrei Vagin <avagin@gmail.com>

* check that a child process is in parent's time namespace after vfork.
* check that a child process is in the target namespace after exec.

Output on success:
 1..4
 ok 1 parent before vfork
 ok 2 child after exec
 ok 3 wait for child
 ok 4 parent after vfork
 # Totals: pass:4 fail:0 xfail:0 xpass:0 skip:0 error:0

Signed-off-by: Andrei Vagin <avagin@gmail.com>
---

v2: - don't create threads from a vfork-ed process.
    - use _exit to exit from a vfork-ed process.

 tools/testing/selftests/timens/.gitignore   |   1 +
 tools/testing/selftests/timens/Makefile     |   2 +-
 tools/testing/selftests/timens/vfork_exec.c | 139 ++++++++++++++++++++
 3 files changed, 141 insertions(+), 1 deletion(-)
 create mode 100644 tools/testing/selftests/timens/vfork_exec.c

diff --git a/tools/testing/selftests/timens/.gitignore b/tools/testing/selftests/timens/.gitignore
index fe1eb8271b35..cae8dca0fbff 100644
--- a/tools/testing/selftests/timens/.gitignore
+++ b/tools/testing/selftests/timens/.gitignore
@@ -8,3 +8,4 @@ procfs
 timens
 timer
 timerfd
+vfork_exec
diff --git a/tools/testing/selftests/timens/Makefile b/tools/testing/selftests/timens/Makefile
index 3a5936cc10ab..f0d51d4d2c87 100644
--- a/tools/testing/selftests/timens/Makefile
+++ b/tools/testing/selftests/timens/Makefile
@@ -1,4 +1,4 @@
-TEST_GEN_PROGS := timens timerfd timer clock_nanosleep procfs exec futex
+TEST_GEN_PROGS := timens timerfd timer clock_nanosleep procfs exec futex vfork_exec
 TEST_GEN_PROGS_EXTENDED := gettime_perf
 
 CFLAGS := -Wall -Werror -pthread
diff --git a/tools/testing/selftests/timens/vfork_exec.c b/tools/testing/selftests/timens/vfork_exec.c
new file mode 100644
index 000000000000..fe3d0e15aa7e
--- /dev/null
+++ b/tools/testing/selftests/timens/vfork_exec.c
@@ -0,0 +1,139 @@
+// 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 <sys/wait.h>
+#include <time.h>
+#include <unistd.h>
+#include <string.h>
+#include <pthread.h>
+
+#include "log.h"
+#include "timens.h"
+
+#define OFFSET (36000)
+
+struct thread_args {
+	char *tst_name;
+	struct timespec *now;
+};
+
+static void *tcheck(void *_args)
+{
+	struct thread_args *args = _args;
+	struct timespec *now = args->now, tst;
+	int i;
+
+	for (i = 0; i < 2; i++) {
+		_gettime(CLOCK_MONOTONIC, &tst, i);
+		if (abs(tst.tv_sec - now->tv_sec) > 5) {
+			pr_fail("%s: in-thread: unexpected value: %ld (%ld)\n",
+				args->tst_name, tst.tv_sec, now->tv_sec);
+			return (void *)1UL;
+		}
+	}
+	return NULL;
+}
+
+static int check_in_thread(char *tst_name, struct timespec *now)
+{
+	struct thread_args args = {
+		.tst_name = tst_name,
+		.now = now,
+	};
+	pthread_t th;
+	void *retval;
+
+	if (pthread_create(&th, NULL, tcheck, &args))
+		return pr_perror("thread");
+	if (pthread_join(th, &retval))
+		return pr_perror("pthread_join");
+	return !(retval == NULL);
+}
+
+static int check(char *tst_name, struct timespec *now)
+{
+	struct timespec tst;
+	int i;
+
+	for (i = 0; i < 2; i++) {
+		_gettime(CLOCK_MONOTONIC, &tst, i);
+		if (abs(tst.tv_sec - now->tv_sec) > 5)
+			return pr_fail("%s: unexpected value: %ld (%ld)\n",
+					tst_name, tst.tv_sec, now->tv_sec);
+	}
+	if (check_in_thread(tst_name, now))
+		return 1;
+	ksft_test_result_pass("%s\n", tst_name);
+	return 0;
+}
+
+int main(int argc, char *argv[])
+{
+	struct timespec now;
+	int status;
+	pid_t pid;
+
+	if (argc > 1) {
+		char *endptr;
+
+		ksft_cnt.ksft_pass = 1;
+		now.tv_sec = strtoul(argv[1], &endptr, 0);
+		if (*endptr != 0)
+			return pr_perror("strtoul");
+
+		return check("child after exec", &now);
+	}
+
+	nscheck();
+
+	ksft_set_plan(4);
+
+	clock_gettime(CLOCK_MONOTONIC, &now);
+
+	if (unshare_timens())
+		return 1;
+
+	if (_settime(CLOCK_MONOTONIC, OFFSET))
+		return 1;
+
+	if (check("parent before vfork", &now))
+		return 1;
+
+	pid = vfork();
+	if (pid < 0)
+		return pr_perror("fork");
+
+	if (pid == 0) {
+		char now_str[64];
+		char *cargv[] = {"exec", now_str, NULL};
+		char *cenv[] = {NULL};
+
+		/* Check for proper vvar offsets after execve. */
+		snprintf(now_str, sizeof(now_str), "%ld", now.tv_sec + OFFSET);
+		execve("/proc/self/exe", cargv, cenv);
+		pr_perror("execve");
+		_exit(1);
+	}
+
+	if (waitpid(pid, &status, 0) != pid)
+		return pr_perror("waitpid");
+
+	if (status)
+		ksft_exit_fail();
+	ksft_inc_pass_cnt();
+	ksft_test_result_pass("wait for child\n");
+
+	/* Check that we are still in the source timens. */
+	if (check("parent after vfork", &now))
+		return 1;
+
+	ksft_exit_pass();
+	return 0;
+}
-- 
2.38.0.413.g74048e4d9e-goog