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Message-ID: <20241122132459.135120-3-aleksandr.mikhalitsyn@canonical.com>
Date: Fri, 22 Nov 2024 14:24:59 +0100
From: Alexander Mikhalitsyn <aleksandr.mikhalitsyn@...onical.com>
To: brauner@...nel.org
Cc: stgraber@...raber.org,
tycho@...ho.pizza,
cyphar@...har.com,
yun.zhou@...driver.com,
joel.granados@...nel.org,
rostedt@...dmis.org,
linux-kernel@...r.kernel.org,
Christian Brauner <christian.brauner@...ntu.com>,
Alexander Mikhalitsyn <aleksandr.mikhalitsyn@...onical.com>
Subject: [PATCH v2 2/2] tests/pid_namespace: add pid_max tests
From: Christian Brauner <christian.brauner@...ntu.com>
Signed-off-by: Christian Brauner <brauner@...nel.org>
Signed-off-by: Alexander Mikhalitsyn <aleksandr.mikhalitsyn@...onical.com>
---
.../selftests/pid_namespace/.gitignore | 1 +
.../testing/selftests/pid_namespace/Makefile | 2 +-
.../testing/selftests/pid_namespace/pid_max.c | 358 ++++++++++++++++++
3 files changed, 360 insertions(+), 1 deletion(-)
create mode 100644 tools/testing/selftests/pid_namespace/pid_max.c
diff --git a/tools/testing/selftests/pid_namespace/.gitignore b/tools/testing/selftests/pid_namespace/.gitignore
index 93ab9d7e5b7e..5118f0f3edf4 100644
--- a/tools/testing/selftests/pid_namespace/.gitignore
+++ b/tools/testing/selftests/pid_namespace/.gitignore
@@ -1 +1,2 @@
+pid_max
regression_enomem
diff --git a/tools/testing/selftests/pid_namespace/Makefile b/tools/testing/selftests/pid_namespace/Makefile
index 9286a1d22cd3..b972f55d07ae 100644
--- a/tools/testing/selftests/pid_namespace/Makefile
+++ b/tools/testing/selftests/pid_namespace/Makefile
@@ -1,7 +1,7 @@
# SPDX-License-Identifier: GPL-2.0
CFLAGS += -g $(KHDR_INCLUDES)
-TEST_GEN_PROGS = regression_enomem
+TEST_GEN_PROGS = regression_enomem pid_max
LOCAL_HDRS += $(selfdir)/pidfd/pidfd.h
diff --git a/tools/testing/selftests/pid_namespace/pid_max.c b/tools/testing/selftests/pid_namespace/pid_max.c
new file mode 100644
index 000000000000..51c414faabb0
--- /dev/null
+++ b/tools/testing/selftests/pid_namespace/pid_max.c
@@ -0,0 +1,358 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#define _GNU_SOURCE
+#include <assert.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <linux/types.h>
+#include <sched.h>
+#include <signal.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <syscall.h>
+#include <sys/wait.h>
+
+#include "../kselftest_harness.h"
+#include "../pidfd/pidfd.h"
+
+#define __STACK_SIZE (8 * 1024 * 1024)
+static pid_t do_clone(int (*fn)(void *), void *arg, int flags)
+{
+ char *stack;
+ pid_t ret;
+
+ stack = malloc(__STACK_SIZE);
+ if (!stack)
+ return -ENOMEM;
+
+#ifdef __ia64__
+ ret = __clone2(fn, stack, __STACK_SIZE, flags | SIGCHLD, arg);
+#else
+ ret = clone(fn, stack + __STACK_SIZE, flags | SIGCHLD, arg);
+#endif
+ free(stack);
+ return ret;
+}
+
+static int pid_max_cb(void *data)
+{
+ int fd, ret;
+ pid_t pid;
+
+ ret = mount("", "/", NULL, MS_PRIVATE | MS_REC, 0);
+ if (ret) {
+ fprintf(stderr, "%m - Failed to make rootfs private mount\n");
+ return -1;
+ }
+
+ umount2("/proc", MNT_DETACH);
+
+ ret = mount("proc", "/proc", "proc", 0, NULL);
+ if (ret) {
+ fprintf(stderr, "%m - Failed to mount proc\n");
+ return -1;
+ }
+
+ fd = open("/proc/sys/kernel/pid_max", O_RDWR | O_CLOEXEC | O_NOCTTY);
+ if (fd < 0) {
+ fprintf(stderr, "%m - Failed to open pid_max\n");
+ return -1;
+ }
+
+ ret = write(fd, "500", sizeof("500") - 1);
+ if (ret < 0) {
+ fprintf(stderr, "%m - Failed to write pid_max\n");
+ return -1;
+ }
+
+ for (int i = 0; i < 501; i++) {
+ pid = fork();
+ if (pid == 0)
+ exit(EXIT_SUCCESS);
+ wait_for_pid(pid);
+ if (pid > 500) {
+ fprintf(stderr, "Managed to create pid number beyond limit\n");
+ return -1;
+ }
+ }
+
+ return 0;
+}
+
+static int pid_max_nested_inner(void *data)
+{
+ int fret = -1;
+ pid_t pids[2];
+ int fd, i, ret;
+
+ ret = mount("", "/", NULL, MS_PRIVATE | MS_REC, 0);
+ if (ret) {
+ fprintf(stderr, "%m - Failed to make rootfs private mount\n");
+ return fret;
+ }
+
+ umount2("/proc", MNT_DETACH);
+
+ ret = mount("proc", "/proc", "proc", 0, NULL);
+ if (ret) {
+ fprintf(stderr, "%m - Failed to mount proc\n");
+ return fret;
+ }
+
+ fd = open("/proc/sys/kernel/pid_max", O_RDWR | O_CLOEXEC | O_NOCTTY);
+ if (fd < 0) {
+ fprintf(stderr, "%m - Failed to open pid_max\n");
+ return fret;
+ }
+
+ ret = write(fd, "500", sizeof("500") - 1);
+ close(fd);
+ if (ret < 0) {
+ fprintf(stderr, "%m - Failed to write pid_max\n");
+ return fret;
+ }
+
+ pids[0] = fork();
+ if (pids[0] < 0) {
+ fprintf(stderr, "Failed to create first new process\n");
+ return fret;
+ }
+
+ if (pids[0] == 0)
+ exit(EXIT_SUCCESS);
+
+ pids[1] = fork();
+ wait_for_pid(pids[0]);
+ if (pids[1] >= 0) {
+ if (pids[1] == 0)
+ exit(EXIT_SUCCESS);
+ wait_for_pid(pids[1]);
+
+ fprintf(stderr, "Managed to create process even though ancestor pid namespace had a limit\n");
+ return fret;
+ }
+
+ /* Now make sure that we wrap pids at 400. */
+ for (i = 0; i < 510; i++) {
+ pid_t pid;
+
+ pid = fork();
+ if (pid < 0)
+ return fret;
+
+ if (pid == 0)
+ exit(EXIT_SUCCESS);
+
+ wait_for_pid(pid);
+ if (pid >= 500) {
+ fprintf(stderr, "Managed to create process with pid %d beyond configured limit\n", pid);
+ return fret;
+ }
+ }
+
+ return 0;
+}
+
+static int pid_max_nested_outer(void *data)
+{
+ int fret = -1, nr_procs = 400;
+ pid_t pids[1000];
+ int fd, i, ret;
+ pid_t pid;
+
+ ret = mount("", "/", NULL, MS_PRIVATE | MS_REC, 0);
+ if (ret) {
+ fprintf(stderr, "%m - Failed to make rootfs private mount\n");
+ return fret;
+ }
+
+ umount2("/proc", MNT_DETACH);
+
+ ret = mount("proc", "/proc", "proc", 0, NULL);
+ if (ret) {
+ fprintf(stderr, "%m - Failed to mount proc\n");
+ return fret;
+ }
+
+ fd = open("/proc/sys/kernel/pid_max", O_RDWR | O_CLOEXEC | O_NOCTTY);
+ if (fd < 0) {
+ fprintf(stderr, "%m - Failed to open pid_max\n");
+ return fret;
+ }
+
+ ret = write(fd, "400", sizeof("400") - 1);
+ close(fd);
+ if (ret < 0) {
+ fprintf(stderr, "%m - Failed to write pid_max\n");
+ return fret;
+ }
+
+ /*
+ * Create 397 processes. This leaves room for do_clone() (398) and
+ * one more 399. So creating another process needs to fail.
+ */
+ for (nr_procs = 0; nr_procs < 396; nr_procs++) {
+ pid = fork();
+ if (pid < 0)
+ goto reap;
+
+ if (pid == 0)
+ exit(EXIT_SUCCESS);
+
+ pids[nr_procs] = pid;
+ }
+
+ pid = do_clone(pid_max_nested_inner, NULL, CLONE_NEWPID | CLONE_NEWNS);
+ if (pid < 0) {
+ fprintf(stderr, "%m - Failed to clone nested pidns\n");
+ goto reap;
+ }
+
+ if (wait_for_pid(pid)) {
+ fprintf(stderr, "%m - Nested pid_max failed\n");
+ goto reap;
+ }
+
+ fret = 0;
+
+reap:
+ for (int i = 0; i < nr_procs; i++)
+ wait_for_pid(pids[i]);
+
+ return fret;
+}
+
+static int pid_max_nested_limit_inner(void *data)
+{
+ int fret = -1, nr_procs = 400;
+ int fd, ret;
+ pid_t pid;
+ pid_t pids[1000];
+
+ ret = mount("", "/", NULL, MS_PRIVATE | MS_REC, 0);
+ if (ret) {
+ fprintf(stderr, "%m - Failed to make rootfs private mount\n");
+ return fret;
+ }
+
+ umount2("/proc", MNT_DETACH);
+
+ ret = mount("proc", "/proc", "proc", 0, NULL);
+ if (ret) {
+ fprintf(stderr, "%m - Failed to mount proc\n");
+ return fret;
+ }
+
+ fd = open("/proc/sys/kernel/pid_max", O_RDWR | O_CLOEXEC | O_NOCTTY);
+ if (fd < 0) {
+ fprintf(stderr, "%m - Failed to open pid_max\n");
+ return fret;
+ }
+
+ ret = write(fd, "500", sizeof("500") - 1);
+ close(fd);
+ if (ret < 0) {
+ fprintf(stderr, "%m - Failed to write pid_max\n");
+ return fret;
+ }
+
+ for (nr_procs = 0; nr_procs < 500; nr_procs++) {
+ pid = fork();
+ if (pid < 0)
+ break;
+
+ if (pid == 0)
+ exit(EXIT_SUCCESS);
+
+ pids[nr_procs] = pid;
+ }
+
+ if (nr_procs >= 400) {
+ fprintf(stderr, "Managed to create processes beyond the configured outer limit\n");
+ goto reap;
+ }
+
+ fret = 0;
+
+reap:
+ for (int i = 0; i < nr_procs; i++)
+ wait_for_pid(pids[i]);
+
+ return fret;
+}
+
+static int pid_max_nested_limit_outer(void *data)
+{
+ int fd, ret;
+ pid_t pid;
+
+ ret = mount("", "/", NULL, MS_PRIVATE | MS_REC, 0);
+ if (ret) {
+ fprintf(stderr, "%m - Failed to make rootfs private mount\n");
+ return -1;
+ }
+
+ umount2("/proc", MNT_DETACH);
+
+ ret = mount("proc", "/proc", "proc", 0, NULL);
+ if (ret) {
+ fprintf(stderr, "%m - Failed to mount proc\n");
+ return -1;
+ }
+
+ fd = open("/proc/sys/kernel/pid_max", O_RDWR | O_CLOEXEC | O_NOCTTY);
+ if (fd < 0) {
+ fprintf(stderr, "%m - Failed to open pid_max\n");
+ return -1;
+ }
+
+ ret = write(fd, "400", sizeof("400") - 1);
+ close(fd);
+ if (ret < 0) {
+ fprintf(stderr, "%m - Failed to write pid_max\n");
+ return -1;
+ }
+
+ pid = do_clone(pid_max_nested_limit_inner, NULL, CLONE_NEWPID | CLONE_NEWNS);
+ if (pid < 0) {
+ fprintf(stderr, "%m - Failed to clone nested pidns\n");
+ return -1;
+ }
+
+ if (wait_for_pid(pid)) {
+ fprintf(stderr, "%m - Nested pid_max failed\n");
+ return -1;
+ }
+
+ return 0;
+}
+
+TEST(pid_max_simple)
+{
+ pid_t pid;
+
+
+ pid = do_clone(pid_max_cb, NULL, CLONE_NEWPID | CLONE_NEWNS);
+ ASSERT_GT(pid, 0);
+ ASSERT_EQ(0, wait_for_pid(pid));
+}
+
+TEST(pid_max_nested_limit)
+{
+ pid_t pid;
+
+ pid = do_clone(pid_max_nested_limit_outer, NULL, CLONE_NEWPID | CLONE_NEWNS);
+ ASSERT_GT(pid, 0);
+ ASSERT_EQ(0, wait_for_pid(pid));
+}
+
+TEST(pid_max_nested)
+{
+ pid_t pid;
+
+ pid = do_clone(pid_max_nested_outer, NULL, CLONE_NEWPID | CLONE_NEWNS);
+ ASSERT_GT(pid, 0);
+ ASSERT_EQ(0, wait_for_pid(pid));
+}
+
+TEST_HARNESS_MAIN
--
2.43.0
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