1 files changed, 79 insertions, 0 deletions
diff --git a/tools/testing/selftests/nsfs/pidns.c b/tools/testing/selftests/nsfs/pidns.c
new file mode 100644
index 0000000000..e3c772c6a7
--- /dev/null
+++ b/tools/testing/selftests/nsfs/pidns.c
@@ -0,0 +1,79 @@
+// SPDX-License-Identifier: GPL-2.0
+#define _GNU_SOURCE
+#include <sched.h>
+#include <unistd.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <signal.h>
+#include <errno.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#include <sys/ioctl.h>
+#include <sys/prctl.h>
+#include <sys/wait.h>
+
+#define pr_err(fmt, ...) \
+		({ \
+			fprintf(stderr, "%s:%d:" fmt ": %m\n", \
+				__func__, __LINE__, ##__VA_ARGS__); \
+			1; \
+		})
+
+#define NSIO	0xb7
+#define NS_GET_USERNS   _IO(NSIO, 0x1)
+#define NS_GET_PARENT   _IO(NSIO, 0x2)
+
+#define __stack_aligned__	__attribute__((aligned(16)))
+struct cr_clone_arg {
+	char stack[128] __stack_aligned__;
+	char stack_ptr[];
+};
+
+static int child(void *args)
+{
+	prctl(PR_SET_PDEATHSIG, SIGKILL);
+	while (1)
+		sleep(1);
+	exit(0);
+}
+
+int main(int argc, char *argv[])
+{
+	char *ns_strs[] = {"pid", "user"};
+	char path[] = "/proc/0123456789/ns/pid";
+	struct cr_clone_arg ca;
+	struct stat st1, st2;
+	int ns, pns, i;
+	pid_t pid;
+
+	pid = clone(child, ca.stack_ptr, CLONE_NEWUSER | CLONE_NEWPID | SIGCHLD, NULL);
+	if (pid < 0)
+		return pr_err("clone");
+
+	for (i = 0; i < 2; i++) {
+		snprintf(path, sizeof(path), "/proc/%d/ns/%s", pid, ns_strs[i]);
+		ns = open(path, O_RDONLY);
+		if (ns < 0)
+			return pr_err("Unable to open %s", path);
+
+		pns = ioctl(ns, NS_GET_PARENT);
+		if (pns < 0)
+			return pr_err("Unable to get a parent pidns");
+
+		snprintf(path, sizeof(path), "/proc/self/ns/%s", ns_strs[i]);
+		if (stat(path, &st2))
+			return pr_err("Unable to stat %s", path);
+		if (fstat(pns, &st1))
+			return pr_err("Unable to stat the parent pidns");
+		if (st1.st_ino != st2.st_ino)
+			return pr_err("NS_GET_PARENT returned a wrong namespace");
+
+		if (ioctl(pns, NS_GET_PARENT) >= 0 || errno != EPERM)
+			return pr_err("Don't get EPERM");
+	}
+
+	kill(pid, SIGKILL);
+	wait(NULL);
+	return 0;
+}