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-rw-r--r--tools/testing/selftests/proc/setns-dcache.c129
1 files changed, 129 insertions, 0 deletions
diff --git a/tools/testing/selftests/proc/setns-dcache.c b/tools/testing/selftests/proc/setns-dcache.c
new file mode 100644
index 000000000..60ab197a7
--- /dev/null
+++ b/tools/testing/selftests/proc/setns-dcache.c
@@ -0,0 +1,129 @@
+/*
+ * Copyright © 2019 Alexey Dobriyan <adobriyan@gmail.com>
+ *
+ * Permission to use, copy, modify, and distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+/*
+ * Test that setns(CLONE_NEWNET) points to new /proc/net content even
+ * if old one is in dcache.
+ *
+ * FIXME /proc/net/unix is under CONFIG_UNIX which can be disabled.
+ */
+#undef NDEBUG
+#include <assert.h>
+#include <errno.h>
+#include <sched.h>
+#include <signal.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#include <sys/socket.h>
+
+static pid_t pid = -1;
+
+static void f(void)
+{
+ if (pid > 0) {
+ kill(pid, SIGTERM);
+ }
+}
+
+int main(void)
+{
+ int fd[2];
+ char _ = 0;
+ int nsfd;
+
+ atexit(f);
+
+ /* Check for priviledges and syscall availability straight away. */
+ if (unshare(CLONE_NEWNET) == -1) {
+ if (errno == ENOSYS || errno == EPERM) {
+ return 4;
+ }
+ return 1;
+ }
+ /* Distinguisher between two otherwise empty net namespaces. */
+ if (socket(AF_UNIX, SOCK_STREAM, 0) == -1) {
+ return 1;
+ }
+
+ if (pipe(fd) == -1) {
+ return 1;
+ }
+
+ pid = fork();
+ if (pid == -1) {
+ return 1;
+ }
+
+ if (pid == 0) {
+ if (unshare(CLONE_NEWNET) == -1) {
+ return 1;
+ }
+
+ if (write(fd[1], &_, 1) != 1) {
+ return 1;
+ }
+
+ pause();
+
+ return 0;
+ }
+
+ if (read(fd[0], &_, 1) != 1) {
+ return 1;
+ }
+
+ {
+ char buf[64];
+ snprintf(buf, sizeof(buf), "/proc/%u/ns/net", pid);
+ nsfd = open(buf, O_RDONLY);
+ if (nsfd == -1) {
+ return 1;
+ }
+ }
+
+ /* Reliably pin dentry into dcache. */
+ (void)open("/proc/net/unix", O_RDONLY);
+
+ if (setns(nsfd, CLONE_NEWNET) == -1) {
+ return 1;
+ }
+
+ kill(pid, SIGTERM);
+ pid = 0;
+
+ {
+ char buf[4096];
+ ssize_t rv;
+ int fd;
+
+ fd = open("/proc/net/unix", O_RDONLY);
+ if (fd == -1) {
+ return 1;
+ }
+
+#define S "Num RefCount Protocol Flags Type St Inode Path\n"
+ rv = read(fd, buf, sizeof(buf));
+
+ assert(rv == strlen(S));
+ assert(memcmp(buf, S, strlen(S)) == 0);
+ }
+
+ return 0;
+}