Implement decoding of NS_* ioctl commands

* configure.ac (AC_CHECK_HEADERS): Add linux/nsfs.h.
* defs.h (DECL_IOCTL(nsfs)): New prototype.
(setns_types): Make global.
* ioctl.c (ioctl_decode): Call nsfs_ioctl for 0xb7 code.
* nsfs.c: New file.
* nsfs.h: Likewise.
* Makefile.am (strace_SOURCES): Add them.
* tests/ioctl_nsfs.c: New file.
* tests/ioctl_nsfs.test: Likewise.
* tests/.gitignore: Add ioctl_nsfs.
* tests/Makefile.am (check_PROGRAMS): Likewise.
(DECODER_TESTS): Add ioctl_nsfs.test.
* NEWS: Mention this change.

1 files changed, 139 insertions, 0 deletions

diff --git a/tests/ioctl_nsfs.c b/tests/ioctl_nsfs.c
new file mode 100644
index 000000000..02612354f
--- /dev/null
+++ b/tests/ioctl_nsfs.c
@@ -0,0 +1,139 @@
+/*
+ * Check decoding of NS_* commands of ioctl syscall.
+ *
+ * Copyright (c) 2017 Nikolay Marchuk <marchuk.nikolay.a@gmail.com>
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. The name of the author may not be used to endorse or promote products
+ *    derived from this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
+ * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+ * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
+ * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+ * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
+ * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include "tests.h"
+
+#include <fcntl.h>
+#include <sched.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <sys/ioctl.h>
+#include <sys/wait.h>
+#include <unistd.h>
+#include "nsfs.h"
+
+#ifndef CLONE_NEWUSER
+# define CLONE_NEWUSER 0x10000000
+#endif
+
+static void
+test_no_namespace(void)
+{
+	ioctl(-1, NS_GET_USERNS);
+	printf("ioctl(-1, NS_GET_USERNS) = -1 EBADF (%m)\n");
+	ioctl(-1, NS_GET_PARENT);
+	printf("ioctl(-1, NS_GET_PARENT) = -1 EBADF (%m)\n");
+	ioctl(-1, NS_GET_NSTYPE);
+	printf("ioctl(-1, NS_GET_NSTYPE) = -1 EBADF (%m)\n");
+	ioctl(-1, NS_GET_OWNER_UID, NULL);
+	printf("ioctl(-1, NS_GET_OWNER_UID, NULL) = -1 EBADF (%m)\n");
+}
+
+static void
+test_clone(pid_t pid)
+{
+	char path[sizeof("/proc/%d/ns/user") + sizeof(int)*3];
+	snprintf(path, sizeof(path), "/proc/%d/ns/user", pid);
+
+	int ns_fd = open(path, O_RDONLY);
+	if (ns_fd == -1)
+		perror_msg_and_skip("open: %s", path);
+
+	int userns_fd = ioctl(ns_fd, NS_GET_USERNS);
+	printf("ioctl(%d, NS_GET_USERNS) = %s\n", ns_fd, sprintrc(userns_fd));
+
+	int parent_ns_fd = ioctl(userns_fd, NS_GET_PARENT);
+	printf("ioctl(%d, NS_GET_PARENT) = %s\n",
+	       userns_fd, sprintrc(parent_ns_fd));
+
+	int nstype = ioctl(userns_fd, NS_GET_NSTYPE);
+	if (nstype == -1) {
+		printf("ioctl(%d, NS_GET_NSTYPE) = %s\n",
+		       userns_fd, sprintrc(nstype));
+	} else {
+		printf("ioctl(%d, NS_GET_NSTYPE) = %d (CLONE_NEWUSER)\n",
+		       userns_fd, nstype);
+	}
+
+	TAIL_ALLOC_OBJECT_CONST_PTR(unsigned int, uid);
+	int rc = ioctl(userns_fd, NS_GET_OWNER_UID, uid);
+	if (rc == -1) {
+		printf("ioctl(%d, NS_GET_OWNER_UID, %p) = %s\n",
+		       userns_fd, uid, sprintrc(rc));
+	} else {
+		printf("ioctl(%d, NS_GET_OWNER_UID, [%u]) = %d\n",
+		       userns_fd, *uid, rc);
+	}
+}
+
+static int
+child(void *arg)
+{
+	int *pipefd = (int *) arg;
+	close(pipefd[1]);
+	/* Wait for EOF from pipe. */
+	if (read(pipefd[0], &pipefd[1], 1))
+		perror_msg_and_fail("read");
+	return 0;
+}
+
+static void
+test_user_namespace(void)
+{
+	pid_t pid;
+	int pipefd[2];
+	int status;
+
+	if (pipe(pipefd))
+		perror_msg_and_fail("pipe");
+
+	pid = clone(child, tail_alloc(1) + 1,
+		    CLONE_NEWUSER | CLONE_UNTRACED | SIGCHLD, pipefd);
+	if (pid == -1) {
+		perror("clone");
+		return;
+	}
+	close(pipefd[0]);
+	test_clone(pid);
+	close(pipefd[1]);
+	if (wait(&status) != pid) {
+		perror_msg_and_fail("wait");
+	} else if (status != 0) {
+		error_msg_and_fail("unexpected child exit status %d", status);
+	}
+}
+
+int
+main(void)
+{
+	test_no_namespace();
+	test_user_namespace();
+	puts("+++ exited with 0 +++");
+	return 0;
+}