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Date: Sun, 22 Aug 2021 20:29:09 -0700
From: Ran Xiaokai <cgel.zte@...il.com>
To: christian.brauner@...ntu.com
Cc: cgel.zte@...il.com, dbueso@...e.de, jamorris@...ux.microsoft.com,
keescook@...omium.org, ktkhai@...tuozzo.com, legion@...nel.org,
linux-kernel@...r.kernel.org, ran.xiaokai@....com.cn,
varad.gautam@...e.com
Subject: [PATCH] tests: add mqueue sysctl tests for user namespace
when a ipc namespace is created in a user namespace, the mqueue sysctl
files should be writalbe to the owner of the user namespace. Even the
owner is not a global privileged user.
Signed-off-by: Ran Xiaokai <ran.xiaokai@....com.cn>
---
tools/testing/selftests/Makefile | 1 +
tools/testing/selftests/mqueue_sysctl/Makefile | 7 +
tools/testing/selftests/mqueue_sysctl/config | 2 +
.../selftests/mqueue_sysctl/mq_sysctl_test.c | 172 +++++++++++++++++++++
4 files changed, 182 insertions(+)
create mode 100644 tools/testing/selftests/mqueue_sysctl/Makefile
create mode 100644 tools/testing/selftests/mqueue_sysctl/config
create mode 100644 tools/testing/selftests/mqueue_sysctl/mq_sysctl_test.c
diff --git a/tools/testing/selftests/Makefile b/tools/testing/selftests/Makefile
index bc3299a..2031591 100644
--- a/tools/testing/selftests/Makefile
+++ b/tools/testing/selftests/Makefile
@@ -36,6 +36,7 @@ TARGETS += mincore
TARGETS += mount
TARGETS += mount_setattr
TARGETS += mqueue
+TARGETS += mqueue_sysctl
TARGETS += nci
TARGETS += net
TARGETS += net/forwarding
diff --git a/tools/testing/selftests/mqueue_sysctl/Makefile b/tools/testing/selftests/mqueue_sysctl/Makefile
new file mode 100644
index 0000000..44b6633
--- /dev/null
+++ b/tools/testing/selftests/mqueue_sysctl/Makefile
@@ -0,0 +1,7 @@
+# SPDX-License-Identifier: GPL-2.0
+CFLAGS += -O2
+LDLIBS = -lrt
+
+TEST_GEN_PROGS := mq_sysctl_test
+
+include ../lib.mk
diff --git a/tools/testing/selftests/mqueue_sysctl/config b/tools/testing/selftests/mqueue_sysctl/config
new file mode 100644
index 0000000..68b2794
--- /dev/null
+++ b/tools/testing/selftests/mqueue_sysctl/config
@@ -0,0 +1,2 @@
+CONFIG_USER_NS=y
+CONFIG_POSIX_MQUEUE_SYSCTL=y
\ No newline at end of file
diff --git a/tools/testing/selftests/mqueue_sysctl/mq_sysctl_test.c b/tools/testing/selftests/mqueue_sysctl/mq_sysctl_test.c
new file mode 100644
index 0000000..48023d5
--- /dev/null
+++ b/tools/testing/selftests/mqueue_sysctl/mq_sysctl_test.c
@@ -0,0 +1,172 @@
+// SPDX-License-Identifier: GPL-2.0
+#define _GNU_SOURCE
+#include <stdio.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#include <unistd.h>
+#include <errno.h>
+#include <sched.h>
+#include <sys/mount.h>
+#include <mqueue.h>
+#include <sys/wait.h>
+#include <string.h>
+
+#include "../kselftest_harness.h"
+
+static ssize_t write_nointr(int fd, const void *buf, size_t count)
+{
+ ssize_t ret;
+
+ do {
+ ret = write(fd, buf, count);
+ } while (ret < 0 && errno == EINTR);
+
+ return ret;
+}
+
+static int write_file(const char *path, const void *buf, size_t count)
+{
+ int fd;
+ ssize_t ret;
+
+ fd = open(path, O_WRONLY | O_CLOEXEC | O_NOCTTY | O_NOFOLLOW);
+ if (fd < 0)
+ return -1;
+
+ ret = write_nointr(fd, buf, count);
+ close(fd);
+ if (ret < 0 || (size_t)ret != count)
+ return -1;
+
+ return 0;
+}
+
+static int create_and_enter_userns(void)
+{
+ uid_t uid;
+ gid_t gid;
+ char map[100];
+
+ uid = getuid();
+ gid = getgid();
+
+ if (unshare(CLONE_NEWUSER))
+ return -1;
+
+ if (write_file("/proc/self/setgroups", "deny", sizeof("deny") - 1) &&
+ errno != ENOENT)
+ return -1;
+
+ snprintf(map, sizeof(map), "0 %d 1", uid);
+ if (write_file("/proc/self/uid_map", map, strlen(map)))
+ return -1;
+
+ snprintf(map, sizeof(map), "0 %d 1", gid);
+ if (write_file("/proc/self/gid_map", map, strlen(map)))
+ return -1;
+
+ if (setgid(0))
+ return -1;
+
+ if (setuid(0))
+ return -1;
+
+ return 0;
+}
+
+static int prepare_unpriv_mountns(void)
+{
+ if (create_and_enter_userns())
+ return -1;
+
+ if (unshare(CLONE_NEWNS))
+ return -1;
+
+ if (mount(NULL, "/", NULL, MS_REC | MS_PRIVATE, 0))
+ return -1;
+
+ if (unshare(CLONE_NEWIPC))
+ return -1;
+
+ return 0;
+}
+
+static 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 (!WIFEXITED(status))
+ return -1;
+
+ return WEXITSTATUS(status);
+}
+
+int get_mq_queues_max(void)
+{
+ int fd;
+ char buf[16];
+ int val = -1;
+
+ fd = open("/proc/sys/fs/mqueue/queues_max", O_RDONLY);
+ if (fd >= 0) {
+ if (read(fd, buf, sizeof(buf)) > 0)
+ val = atoi(buf);
+
+ close(fd);
+ return val;
+ }
+ return val;
+}
+
+TEST(mqueue_sysctl)
+{
+ pid_t pid;
+ int qmax1, qmax2;
+
+ chdir(getenv("HOME"));
+ /* read and stash the original sysctl value */
+ qmax1 = get_mq_queues_max();
+ ASSERT_GE(qmax1, 0);
+
+ pid = fork();
+ ASSERT_GE(pid, 0);
+
+ if (pid == 0) {
+ ASSERT_EQ(prepare_unpriv_mountns(), 0);
+
+ if (mkdir("./mqueue", 755) && errno != EEXIST)
+ SKIP(return, "mkdir /dev/mqueue failed");
+
+ ASSERT_EQ(mount("none", "./mqueue", "mqueue", MS_NOATIME, NULL), 0);
+
+ /* modify the sysctl value in new ipc namesapce */
+ ASSERT_EQ(write_file("/proc/sys/fs/mqueue/queues_max", "1", 1), 0);
+
+ ASSERT_GE(mq_open("/new_ns1", O_RDWR | O_CREAT, 0644, NULL), 0);
+
+ /* mq_open() should fail as exceeding of queues_max */
+ ASSERT_EQ(mq_open("/new_ns2", O_RDWR | O_CREAT, 0644, NULL), -1);
+
+ ASSERT_EQ(mq_unlink("/new_ns1"), 0);
+ ASSERT_EQ(umount("./mqueue"), 0);
+
+ exit(0);
+ }
+
+ ASSERT_EQ(wait_for_pid(pid), 0);
+
+ qmax2 = get_mq_queues_max();
+ ASSERT_EQ(qmax1, qmax2);
+}
+
+TEST_HARNESS_MAIN
--
2.15.2
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