[PATCH 4/4] tests: add pidctl() tests

[Christian Brauner <christian@brauner.io>]

This adds test cases for all three subcommands and verifies that they
succeed and fail as expected.
Additionally, the tests verify that pidctl() pidfds are correctly useable
with pidfd_send_signal().

Signed-off-by: Christian Brauner <christian@brauner.io>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Jann Horn <jannh@google.com
Cc: David Howells <dhowells@redhat.com>
Cc: "Michael Kerrisk (man-pages)" <mtk.manpages@gmail.com>
Cc: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Cc: Jonathan Kowalski <bl0pbl33p@gmail.com>
Cc: "Dmitry V. Levin" <ldv@altlinux.org>
Cc: Andy Lutomirsky <luto@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Nagarathnam Muthusamy <nagarathnam.muthusamy@oracle.com>
Cc: Aleksa Sarai <cyphar@cyphar.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
---
 tools/testing/selftests/pidfd/Makefile      |   2 +-
 tools/testing/selftests/pidfd/pidctl_test.c | 553 ++++++++++++++++++++
 2 files changed, 554 insertions(+), 1 deletion(-)
 create mode 100644 tools/testing/selftests/pidfd/pidctl_test.c

diff --git a/tools/testing/selftests/pidfd/Makefile b/tools/testing/selftests/pidfd/Makefile
index deaf8073bc06..29dfa29b3afa 100644
--- a/tools/testing/selftests/pidfd/Makefile
+++ b/tools/testing/selftests/pidfd/Makefile
@@ -1,6 +1,6 @@
 CFLAGS += -g -I../../../../usr/include/
 
-TEST_GEN_PROGS := pidfd_test
+TEST_GEN_PROGS := pidfd_test pidctl_test
 
 include ../lib.mk
 
diff --git a/tools/testing/selftests/pidfd/pidctl_test.c b/tools/testing/selftests/pidfd/pidctl_test.c
new file mode 100644
index 000000000000..e274be42acfb
--- /dev/null
+++ b/tools/testing/selftests/pidfd/pidctl_test.c
@@ -0,0 +1,553 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+
+#define _GNU_SOURCE
+#include <errno.h>
+#include <fcntl.h>
+#include <linux/types.h>
+#include <linux/wait.h>
+#include <sched.h>
+#include <signal.h>
+#include <stdbool.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <syscall.h>
+#include <sys/mount.h>
+#include <sys/prctl.h>
+#include <sys/wait.h>
+#include <unistd.h>
+
+#include "../kselftest.h"
+
+static int parent_pidns_fd = -1;
+static pid_t parent_pidns_pid = 0;
+
+static int child_pidns_fd = -1;
+static pid_t child_pidns_pid = 0;
+
+static int cousin_pidns_fd = -1;
+static pid_t cousin_pidns_pid = 0;
+
+static bool pidns_supported = false;
+
+static inline int sys_pidfd_send_signal(int pidfd, int sig, siginfo_t *info,
+					unsigned int flags)
+{
+	return syscall(__NR_pidfd_send_signal, pidfd, sig, info, flags);
+}
+
+static inline int sys_pidctl(unsigned int cmd, pid_t pid, int source,
+			     int target, unsigned int flags)
+{
+	return syscall(__NR_pidctl, cmd, pid, source, target, flags);
+}
+
+struct cr_clone_arg {
+	char stack[128] __attribute__((aligned(16)));
+	char stack_ptr[0];
+};
+
+static int child_pidns_creator(void *args)
+{
+	(void)prctl(PR_SET_PDEATHSIG, SIGKILL);
+	while (1)
+		sleep(5);
+
+	exit(0);
+}
+
+static int prepare_pid_namespaces(void)
+{
+	char path[512];
+	struct cr_clone_arg ca;
+	pid_t pid;
+
+	parent_pidns_fd = open("/proc/self/ns/pid", O_RDONLY | O_CLOEXEC);
+	if (parent_pidns_fd < 0) {
+		ksft_print_msg("failed to open current pid namespace");
+		return -1;
+	}
+	parent_pidns_pid = getpid();
+
+	pid = clone(child_pidns_creator, ca.stack_ptr, CLONE_NEWPID | SIGCHLD,
+		    NULL);
+	if (pid < 0) {
+		ksft_print_msg("failed to clone child-pidns process in new pid namespace");
+		return -1;
+	}
+
+	snprintf(path, sizeof(path), "/proc/%d/ns/pid", pid);
+
+	child_pidns_fd = open(path, O_RDONLY | O_CLOEXEC);
+	if (child_pidns_fd < 0) {
+		ksft_print_msg("failed to open pid namespace");
+		return -1;
+	}
+	child_pidns_pid = pid;
+
+	pid = clone(child_pidns_creator, ca.stack_ptr, CLONE_NEWPID | SIGCHLD,
+		    NULL);
+	if (pid < 0) {
+		ksft_print_msg("failed to clone cousin-pidns process in new pid namespace");
+		return -1;
+	}
+
+	snprintf(path, sizeof(path), "/proc/%d/ns/pid", pid);
+
+	cousin_pidns_fd = open(path, O_RDONLY | O_CLOEXEC);
+	if (cousin_pidns_fd < 0) {
+		ksft_print_msg("failed to open cousin pid namespace");
+		return -1;
+	}
+	cousin_pidns_pid = pid;
+
+	return 0;
+}
+
+static int test_pidcmd_query_pid(void)
+{
+	const char *test_name = "pidctl PIDCMD_QUERY_PID";
+	pid_t pid, self;
+	int parent_pidns_fd2;
+
+	self = getpid();
+
+	pid = sys_pidctl(PIDCMD_QUERY_PID, self, -1, -1, PIDCTL_CLOEXEC);
+	if (pid >= 0) {
+		ksft_print_msg("%s test %d: managed to pass invalid flag\n",
+			       test_name, ksft_test_num());
+		return -1;
+	}
+
+	pid = sys_pidctl(PIDCMD_QUERY_PID, self, -1, -1, 0);
+	if (!pid || (pid != self)) {
+		ksft_print_msg("%s test %d: argument pid %d, translated pid %d\n",
+			       test_name, ksft_test_num(), self, pid);
+		return -1;
+	}
+	ksft_inc_pass_cnt();
+
+	if (!pidns_supported)
+		goto out;
+
+	parent_pidns_fd2 = open("/proc/self/ns/pid", O_RDONLY | O_CLOEXEC);
+	if (parent_pidns_fd2 < 0) {
+		ksft_print_msg("%s test %d: Failed to open current pid namespace\n",
+			       test_name, ksft_test_num());
+		return -1;
+	}
+
+	pid = sys_pidctl(PIDCMD_QUERY_PID, self, parent_pidns_fd,
+			 parent_pidns_fd2, 0);
+	if (!pid || (pid != self)) {
+		ksft_print_msg("%s test %d: argument pid %d, translated pid %d\n",
+			       test_name, ksft_test_num(), self, pid);
+		close(parent_pidns_fd2);
+		return -1;
+	}
+	ksft_inc_pass_cnt();
+
+	pid = sys_pidctl(PIDCMD_QUERY_PID, self, -1, parent_pidns_fd2, 0);
+	if (!pid || (pid != self)) {
+		ksft_print_msg("%s test %d: argument pid %d, translated pid %d\n",
+			       test_name, ksft_test_num(), self, pid);
+		close(parent_pidns_fd2);
+		return -1;
+	}
+	ksft_inc_pass_cnt();
+
+	pid = sys_pidctl(PIDCMD_QUERY_PID, self, parent_pidns_fd, -1, 0);
+	if (!pid || (pid != self)) {
+		ksft_print_msg("%s test %d: argument pid %d, translated pid %d\n",
+			       test_name, ksft_test_num(), self, pid);
+		close(parent_pidns_fd2);
+		return -1;
+	}
+	ksft_inc_pass_cnt();
+
+	close(parent_pidns_fd2);
+
+	pid = sys_pidctl(PIDCMD_QUERY_PID, self, parent_pidns_fd,
+			 child_pidns_fd, 0);
+	if (pid != 0) {
+		ksft_print_msg("%s test %d: argument pid %d, translated pid %d\n",
+			       test_name, ksft_test_num(), self, pid);
+		return -1;
+	}
+	ksft_inc_pass_cnt();
+
+	pid = sys_pidctl(PIDCMD_QUERY_PID, self, child_pidns_fd,
+			 parent_pidns_fd, 0);
+	if (pid >= 0 || ((pid < 0) && (errno != ESRCH))) {
+		ksft_print_msg("%s test %d: argument pid %d, translated pid %d\n",
+			       test_name, ksft_test_num(), self, pid);
+		return -1;
+	}
+	ksft_inc_pass_cnt();
+
+	pid = sys_pidctl(PIDCMD_QUERY_PID, child_pidns_pid, parent_pidns_fd,
+			 child_pidns_fd, 0);
+	if (pid != 1) {
+		ksft_print_msg("%s test %d: argument pid %d, translated pid %d\n",
+			       test_name, ksft_test_num(), child_pidns_pid, pid);
+		return -1;
+	}
+	ksft_inc_pass_cnt();
+
+	pid = sys_pidctl(PIDCMD_QUERY_PID, 1, child_pidns_fd, parent_pidns_fd,
+			 0);
+	if (pid != child_pidns_pid) {
+		ksft_print_msg("%s test %d: argument pid %d, translated pid %d\n",
+			       test_name, ksft_test_num(), 1, pid);
+		return -1;
+	}
+	ksft_inc_pass_cnt();
+
+	pid = sys_pidctl(PIDCMD_QUERY_PID, 1, child_pidns_fd, cousin_pidns_fd,
+			 0);
+	if (pid != 0) {
+		ksft_print_msg("%s test %d: argument pid %d, translated pid %d\n",
+			       test_name, ksft_test_num(), 1, pid);
+		return -1;
+	}
+	ksft_inc_pass_cnt();
+
+	pid = sys_pidctl(PIDCMD_QUERY_PID, cousin_pidns_pid, child_pidns_fd,
+			 cousin_pidns_fd, 0);
+	if (pid >= 0 || ((pid < 0) && (errno != ESRCH))) {
+		ksft_print_msg("%s test %d: argument pid %d, translated pid %d\n",
+			       test_name, ksft_test_num(), cousin_pidns_pid, pid);
+		return -1;
+	}
+	ksft_inc_pass_cnt();
+
+out:
+	ksft_test_result_pass("%s test: passed\n", test_name);
+	return 0;
+}
+
+static int test_pidcmd_query_pidns(void)
+{
+	const char *test_name = "pidctl PIDCMD_QUERY_PIDNS";
+	int parent_pidns_fd2;
+	int query;
+
+	query = sys_pidctl(PIDCMD_QUERY_PIDNS, 0, -1, -1, PIDCTL_CLOEXEC);
+	if (query >= 0) {
+		ksft_print_msg("%s test %d: managed to pass invalid flag\n",
+			       test_name, ksft_test_num());
+		return -1;
+	}
+	ksft_inc_pass_cnt();
+
+	query = sys_pidctl(PIDCMD_QUERY_PIDNS, 1234, -1, -1, 0);
+	if (query >= 0)
+		ksft_print_msg("%s test %d: managed to pass invalid pid argument\n",
+			test_name, ksft_test_num());
+	ksft_inc_pass_cnt();
+
+	if (!pidns_supported)
+		goto out;
+
+	parent_pidns_fd2 = open("/proc/self/ns/pid", O_RDONLY | O_CLOEXEC);
+	if (parent_pidns_fd2 < 0) {
+		ksft_print_msg("%s test %d: Failed to open second pid namespace file descriptor\n",
+			       test_name, ksft_test_num());
+		return -1;
+	}
+
+	query = sys_pidctl(PIDCMD_QUERY_PIDNS, 0, parent_pidns_fd,
+			   parent_pidns_fd2, 0);
+	close(parent_pidns_fd2);
+	if (query != PIDNS_EQUAL) {
+		ksft_print_msg("%s test %d: failed to detect that pid namespaces are identical %d\n",
+			       test_name, ksft_test_num(), query);
+		return -1;
+	}
+	ksft_inc_pass_cnt();
+
+	query = sys_pidctl(PIDCMD_QUERY_PIDNS, 0, parent_pidns_fd,
+			   child_pidns_fd, 0);
+	if (query != PIDNS_SOURCE_IS_ANCESTOR) {
+		ksft_print_msg("%s test %d: failed to detect that source pid namespace is ancestor of target pid namespace %d\n",
+			       test_name, ksft_test_num(), query);
+		return -1;
+	}
+	ksft_inc_pass_cnt();
+
+	query = sys_pidctl(PIDCMD_QUERY_PIDNS, 0, child_pidns_fd,
+			   parent_pidns_fd, 0);
+	if (query != PIDNS_TARGET_IS_ANCESTOR) {
+		ksft_print_msg("%s test %d: failed to detect that target pid namespace is ancestor of source pid namespace %d\n",
+			       test_name, ksft_test_num(), query);
+		return -1;
+	}
+	ksft_inc_pass_cnt();
+
+	query = sys_pidctl(PIDCMD_QUERY_PIDNS, 0, child_pidns_fd,
+			   cousin_pidns_fd, 0);
+	if (query != PIDNS_UNRELATED) {
+		ksft_print_msg("%s test %d: failed to detect that pid namespace are not related %d\n",
+			       test_name, ksft_test_num(), query);
+		return -1;
+	}
+	ksft_inc_pass_cnt();
+
+	query = sys_pidctl(PIDCMD_QUERY_PIDNS, 0, child_pidns_fd,
+			   cousin_pidns_fd, 0);
+	if (query != PIDNS_UNRELATED) {
+		ksft_print_msg("%s test %d: failed to detect that pid namespace are not related %d\n",
+			       test_name, ksft_test_num(), query);
+		return -1;
+	}
+	ksft_inc_pass_cnt();
+
+out:
+	ksft_test_result_pass("%s test: passed\n", test_name);
+	return 0;
+}
+
+static int test_pidcmd_get_pidfd(void)
+{
+	const char *test_name = "pidctl PIDCMD_GET_PIDFD";
+	pid_t self;
+	int pidfd, parent_pidns_fd2;
+
+	self = getpid();
+
+	pidfd = sys_pidctl(PIDCMD_GET_PIDFD, self, -1, -1, 0);
+	if (pidfd < 0) {
+		ksft_print_msg("%s test %d: failed to retrieve pidfd\n",
+			       test_name, ksft_test_num());
+		return -1;
+	}
+	close(pidfd);
+	ksft_inc_pass_cnt();
+
+	pidfd = sys_pidctl(PIDCMD_GET_PIDFD, self, -1, -1, PIDCTL_CLOEXEC);
+	if (pidfd < 0) {
+		ksft_print_msg("%s test %d: failed to pass valid flag\n",
+			       test_name, ksft_test_num());
+		return -1;
+	}
+	close(pidfd);
+	ksft_inc_pass_cnt();
+
+	if (!pidns_supported)
+		goto out;
+
+	parent_pidns_fd2 = open("/proc/self/ns/pid", O_RDONLY | O_CLOEXEC);
+	if (parent_pidns_fd2 < 0) {
+		ksft_print_msg("%s test %d: Failed to open current pid namespace\n",
+			       test_name, ksft_test_num());
+		return -1;
+	}
+
+	pidfd = sys_pidctl(PIDCMD_GET_PIDFD, self, parent_pidns_fd,
+			   parent_pidns_fd2, PIDCTL_CLOEXEC);
+	if (pidfd < 0) {
+		ksft_print_msg("%s test %d: failed to retrieve pidfd\n",
+			       test_name, ksft_test_num());
+		close(parent_pidns_fd2);
+		return -1;
+	}
+	close(pidfd);
+	ksft_inc_pass_cnt();
+
+	pidfd = sys_pidctl(PIDCMD_GET_PIDFD, self, -1, parent_pidns_fd2,
+			   PIDCTL_CLOEXEC);
+	if (pidfd < 0) {
+		ksft_print_msg("%s test %d: failed to retrieve pidfd\n",
+			       test_name, ksft_test_num());
+		close(parent_pidns_fd2);
+		return -1;
+	}
+	close(pidfd);
+	ksft_inc_pass_cnt();
+
+	pidfd = sys_pidctl(PIDCMD_GET_PIDFD, self, parent_pidns_fd, -1,
+			   PIDCTL_CLOEXEC);
+	if (pidfd < 0) {
+		ksft_print_msg("%s test %d: failed to retrieve pidfd\n",
+			       test_name, ksft_test_num());
+		close(parent_pidns_fd2);
+		return -1;
+	}
+	close(pidfd);
+	ksft_inc_pass_cnt();
+
+	close(parent_pidns_fd2);
+
+	pidfd = sys_pidctl(PIDCMD_GET_PIDFD, self, parent_pidns_fd,
+			   child_pidns_fd, PIDCTL_CLOEXEC);
+	if (pidfd >= 0 || ((pidfd < 0) && (errno != ENOENT))) {
+		ksft_print_msg("%s test %d: succeeded to retrieve pidfd but should've failed %s\n",
+			       test_name, ksft_test_num(), strerror(errno));
+		return -1;
+	}
+	ksft_inc_pass_cnt();
+
+	pidfd = sys_pidctl(PIDCMD_GET_PIDFD, self, child_pidns_fd,
+			   parent_pidns_fd, PIDCTL_CLOEXEC);
+	if (pidfd >= 0 || ((pidfd < 0) && (errno != ESRCH))) {
+		ksft_print_msg("%s test %d: succeeded to retrieve pidfd but should've failed %s\n",
+			       test_name, ksft_test_num(), strerror(errno));
+		return -1;
+	}
+	ksft_inc_pass_cnt();
+
+	pidfd = sys_pidctl(PIDCMD_GET_PIDFD, 1, child_pidns_fd, parent_pidns_fd,
+			   PIDCTL_CLOEXEC);
+	if (pidfd < 0) {
+		ksft_print_msg("%s test %d: failed to retrieve pidfd\n",
+			       test_name, ksft_test_num());
+		return -1;
+	}
+	close(pidfd);
+	ksft_inc_pass_cnt();
+
+	pidfd = sys_pidctl(PIDCMD_GET_PIDFD, 1, child_pidns_fd, cousin_pidns_fd,
+			   PIDCTL_CLOEXEC);
+	if (pidfd >= 0 || ((pidfd < 0) && (errno != ENOENT))) {
+		ksft_print_msg("%s test %d: succeeded to retrieve pidfd but should've failed %s\n",
+			       test_name, ksft_test_num(), strerror(errno));
+		return -1;
+	}
+	ksft_inc_pass_cnt();
+
+	pidfd = sys_pidctl(PIDCMD_GET_PIDFD, cousin_pidns_pid, child_pidns_fd,
+			   cousin_pidns_fd, PIDCTL_CLOEXEC);
+	if (pidfd >= 0 || ((pidfd < 0) && (errno != ESRCH))) {
+		ksft_print_msg("%s test %d: succeeded to retrieve pidfd but should've failed %s\n",
+			       test_name, ksft_test_num(), strerror(errno));
+		return -1;
+	}
+	ksft_inc_pass_cnt();
+
+out:
+	ksft_test_result_pass("%s test: passed\n", test_name);
+	return 0;
+}
+
+static void test_pidctl_pidfd_send_signal(void)
+{
+	const char *test_name = "pidctl with pidfd_send_signal";
+	int child_pidfd, cousin_pidfd, ret;
+
+	child_pidfd = sys_pidctl(PIDCMD_GET_PIDFD, child_pidns_pid, -1, -1,
+				 PIDCTL_CLOEXEC);
+	if (child_pidfd < 0)
+		ksft_print_msg("%s test %d: failed to retrieve pidfd\n",
+			       test_name, ksft_test_num());
+	ksft_inc_pass_cnt();
+
+	ret = sys_pidfd_send_signal(child_pidfd, SIGKILL, NULL, 0);
+	if (ret < 0) {
+		kill(child_pidns_pid, SIGKILL);
+		ksft_print_msg("%s test %d: failed to send signal via pidfd\n",
+			       test_name, ksft_test_num());
+	}
+	ksft_inc_pass_cnt();
+
+	cousin_pidfd = sys_pidctl(PIDCMD_GET_PIDFD, cousin_pidns_pid, -1, -1,
+				  PIDCTL_CLOEXEC);
+	if (cousin_pidfd < 0)
+		ksft_print_msg("%s test %d: failed to retrieve pidfd\n",
+			       test_name, ksft_test_num());
+	ksft_inc_pass_cnt();
+
+	ret = sys_pidfd_send_signal(cousin_pidfd, SIGKILL, NULL, 0);
+	if (ret < 0) {
+		kill(cousin_pidfd, SIGKILL);
+		ksft_print_msg("%s test %d: failed to send signal via pidfd\n",
+			       test_name, ksft_test_num());
+	}
+	ksft_inc_pass_cnt();
+
+	ksft_test_result_pass("%s test: passed\n", test_name);
+}
+
+int wait_for_pid(pid_t pid)
+{
+	int status, ret;
+
+again:
+	ret = waitpid(pid, &status, 0);
+	if (ret == -1) {
+		if (errno == EINTR)
+			goto again;
+
+		return -1;
+	}
+
+	if (ret != pid)
+		goto again;
+
+	if (!WIFEXITED(status) || WEXITSTATUS(status) != 0)
+		return -1;
+
+	return 0;
+}
+
+int main(int argc, char **argv)
+{
+	int ret;
+	pid_t pid;
+
+	pid = fork();
+	if (pid < 0)
+		ksft_exit_fail_msg("Failed to create new process\n");
+
+	if (pid == 0) {
+		if (unshare(CLONE_NEWPID) < 0)
+			exit(EXIT_FAILURE);
+
+		exit(EXIT_SUCCESS);
+	}
+
+	if (!wait_for_pid(pid))
+		pidns_supported = true;
+
+	ksft_print_header();
+
+	if (pidns_supported)
+		prepare_pid_namespaces();
+	else
+		ksft_print_msg(
+			"kernel does not support pid namespaces: skipping pid namespace parts of testsuite");
+
+	ret = test_pidcmd_query_pid();
+	if (ret < 0) {
+		ksft_print_msg("PIDCMD_QUERY_PID tests failed");
+		goto on_error;
+	}
+
+	ret = test_pidcmd_query_pidns();
+	if (ret < 0) {
+		ksft_print_msg("PIDCMD_QUERY_PIDNS tests failed");
+		goto on_error;
+	}
+
+	ret = test_pidcmd_get_pidfd();
+	if (ret < 0) {
+		ksft_print_msg("PIDCMD_GET_PIDFD tests failed");
+		goto on_error;
+	}
+
+	ret = 0;
+
+on_error:
+	if (pidns_supported)
+		test_pidctl_pidfd_send_signal();
+
+	if (parent_pidns_fd >= 0)
+		close(parent_pidns_fd);
+
+	if (child_pidns_fd >= 0)
+		close(child_pidns_fd);
+
+	if (cousin_pidns_fd >= 0)
+		close(cousin_pidns_fd);
+
+	return !ret ? ksft_exit_pass() : ksft_exit_fail();
+}
-- 
2.21.0