---
samples/containers/test-container.c | 162 +++++++++++++++++++++++++++++++++++
1 file changed, 162 insertions(+)
create mode 100644 samples/containers/test-container.c
diff --git a/samples/containers/test-container.c b/samples/containers/test-container.c
new file mode 100644
index 000000000000..c467b447c63d
--- /dev/null
+++ b/samples/containers/test-container.c
@@ -0,0 +1,162 @@
+/* Container test.
+ *
+ * Copyright (C) 2017 Red Hat, Inc. All Rights Reserved.
+ * Written by David Howells (dhowells@xxxxxxxxxx)
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public Licence
+ * as published by the Free Software Foundation; either version
+ * 2 of the Licence, or (at your option) any later version.
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <errno.h>
+#include <sys/wait.h>
+#include <sys/prctl.h>
+
+#define PR_ERRMSG_ENABLE 48
+#define PR_ERRMSG_READ 49
+
+#define E(x) do { if ((x) == -1) { perror(#x); exit(1); } } while(0)
+
+static __attribute__((noreturn))
+void display_error(const char *s)
+{
+ char buf[4096];
+ int err, n, perr;
+
+ do {
+ err = errno;
+ errno = 0;
+ n = prctl(PR_ERRMSG_READ, buf, sizeof(buf));
+ perr = errno;
+ errno = err;
+ if (n > 0) {
+ fprintf(stderr, "Error: '%s': %*.*s: %m\n", s, n, n, buf);
+ } else {
+ fprintf(stderr, "%s: %m\n", s);
+ }
+ } while (perr == 0);
+
+ exit(1);
+}
+
+#define E_write(fd, s) \
+ do { \
+ if (write(fd, s, sizeof(s) - 1) == -1) \
+ display_error(s); \
+ } while (0)
+
+#define CONTAINER_NEW_FS_NS 0x00000001 /* Dup current fs namespace */
+#define CONTAINER_NEW_EMPTY_FS_NS 0x00000002 /* Provide new empty fs namespace */
+#define CONTAINER_NEW_CGROUP_NS 0x00000004 /* Dup current cgroup namespace [priv] */
+#define CONTAINER_NEW_UTS_NS 0x00000008 /* Dup current uts namespace */
+#define CONTAINER_NEW_IPC_NS 0x00000010 /* Dup current ipc namespace */
+#define CONTAINER_NEW_USER_NS 0x00000020 /* Dup current user namespace */
+#define CONTAINER_NEW_PID_NS 0x00000040 /* Dup current pid namespace */
+#define CONTAINER_NEW_NET_NS 0x00000080 /* Dup current net namespace */
+#define CONTAINER_KILL_ON_CLOSE 0x00000100 /* Kill all member processes when fd closed */
+#define CONTAINER_FD_CLOEXEC 0x00000200 /* Close the fd on exec */
+#define CONTAINER__FLAG_MASK 0x000003ff
+
+#define AT_FSMOUNT_CONTAINER_ROOT 0x2000
+
+static inline int fsopen(const char *fs_name, int containerfd, int flags)
+{
+ return syscall(333, fs_name, containerfd, flags);
+}
+
+static inline int fsmount(int fsfd, int dfd, const char *path,
+ unsigned int at_flags, unsigned int flags)
+{
+ return syscall(334, fsfd, dfd, path, at_flags, flags);
+}
+
+static inline int container_create(const char *name, unsigned int mask)
+{
+ return syscall(335, name, mask, 0, 0, 0);
+}
+
+static inline int fork_into_container(int containerfd)
+{
+ return syscall(336, containerfd);
+}
+
+int main()
+{
+ pid_t pid;
+ int mfd, cfd, ws;
+
+ if (prctl(PR_ERRMSG_ENABLE, 1) < 0) {
+ perror("prctl/en");
+ exit(1);
+ }
+
+ cfd = container_create("foo-test",
+ CONTAINER_NEW_EMPTY_FS_NS |
+ CONTAINER_NEW_UTS_NS |
+ CONTAINER_NEW_IPC_NS |
+ CONTAINER_NEW_USER_NS |
+ CONTAINER_NEW_PID_NS |
+ CONTAINER_KILL_ON_CLOSE |
+ CONTAINER_FD_CLOEXEC);
+ if (cfd == -1) {
+ perror("container_create");
+ exit(1);
+ }
+
+ system("cat /proc/containers");
+
+ /* Open the filesystem that's going to form the container root. */
+ mfd = fsopen("nfs4", cfd, 0);
+ if (mfd == -1) {
+ perror("fsopen/root");
+ exit(1);
+ }
+
+ E_write(mfd, "s foo:/bar");
+ E_write(mfd, "o fsc");
+ E_write(mfd, "o sync");
+ E_write(mfd, "o intr");
+ E_write(mfd, "o vers=4.2");
+ E_write(mfd, "o addr=192.168.1.1");
+ E_write(mfd, "o clientaddr=192.168.1.1");
+ E_write(mfd, "x create");
+
+ /* Mount the container root */
+ if (fsmount(mfd, cfd, "/", AT_FSMOUNT_CONTAINER_ROOT, 0) < 0)
+ display_error("fsmount");
+ E(close(mfd));
+
+ /* Mount procfs within the container */
+ mfd = fsopen("proc", cfd, 0);
+ if (mfd == -1) {
+ perror("fsopen/proc");
+ exit(1);
+ }
+ E_write(mfd, "x create");
+ if (fsmount(mfd, cfd, "proc", 0, 0) < 0)
+ display_error("fsmount");
+ E(close(mfd));
+
+ switch ((pid = fork_into_container(cfd))) {
+ case -1:
+ perror("fork_into_container");
+ exit(1);
+ case 0:
+ close(cfd);
+ setenv("PS1", "container>", 1);
+ execl("/bin/bash", "bash", NULL);
+ perror("execl");
+ exit(1);
+ default:
+ if (waitpid(pid, &ws, 0) < 0) {
+ perror("waitpid");
+ exit(1);
+ }
+ }
+ E(close(cfd));
+ exit(0);
+}
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