net: Basic netns dump/restore skeleton

Signed-off-by: Pavel Emelyanov <xemul@parallels.com>

Makefile

@@ -27,6 +27,7 @@ OBJS		+= parasite-syscall.o
 OBJS		+= cr-restore.o
 OBJS		+= crtools.o
 OBJS		+= image.o
+OBJS		+= net.o
 OBJS		+= proc_parse.o
 OBJS		+= cr-dump.o
 OBJS		+= cr-show.o

crtools.c

@@ -38,6 +38,8 @@ static int parse_ns_string(const char *ptr)
 			opts.namespaces_flags |= CLONE_NEWNS;
 		else if (!strncmp(ptr, "pid", 3))
 			opts.namespaces_flags |= CLONE_NEWPID;
+		else if (!strncmp(ptr, "net", 3))
+			opts.namespaces_flags |= CLONE_NEWNET;
 		else
 			goto bad_ns;
 		ptr += 4;

include/net.h

+#ifndef __CR_NET_H__
+#define __CR_NET_H__
+struct cr_fdset;
+int dump_net_ns(int pid, struct cr_fdset *);
+int prepare_net_ns(int pid);
+#endif

include/syscall-types.h

@@ -53,6 +53,10 @@ struct file_handle;
 #define CLONE_NEWIPC	0x08000000
 #endif
 
+#ifndef CLONE_NEWNET
+#define CLONE_NEWNET	0x40000000
+#endif
+
 #define setns	sys_setns
 
 #endif /* SYSCALL_TYPES_H__ */

namespaces.c

@@ -8,6 +8,7 @@
 #include "ipc_ns.h"
 #include "mount.h"
 #include "namespaces.h"
+#include "net.h"
 
 int switch_ns(int pid, int type, char *ns, int *rst)
 {
@@ -87,6 +88,12 @@ static int do_dump_namespaces(struct pid *ns_pid, unsigned int ns_flags)
 		if (ret < 0)
 			goto err;
 	}
+	if (ns_flags & CLONE_NEWNET) {
+		pr_info("Dump NET namespace info\n");
+		ret = dump_net_ns(ns_pid->real, fdset);
+		if (ret < 0)
+			goto err;
+	}
 err:
 	close_cr_fdset(&fdset);
 	return ret;
@@ -149,6 +156,14 @@ int prepare_namespace(int pid, unsigned long clone_flags)
 	pr_info("Restoring namespaces %d flags 0x%lx\n",
 			pid, clone_flags);
 
+	/*
+	 * On netns restore we launch an IP tool, thus we
+	 * have to restore it _before_ altering the mount
+	 * tree (i.e. -- mnt_ns restoring)
+	 */
+
+	if (clone_flags & CLONE_NEWNET)
+		ret = prepare_net_ns(pid);
 	if (clone_flags & CLONE_NEWUTS)
 		ret = prepare_utsns(pid);
 	if (clone_flags & CLONE_NEWIPC)

net.c

+#include <unistd.h>
+#include "syscall-types.h"
+#include "namespaces.h"
+#include "net.h"
+
+int dump_net_ns(int pid, struct cr_fdset *fds)
+{
+	int ret;
+
+	ret = switch_ns(pid, CLONE_NEWNET, "net", NULL);
+
+	return ret;
+}
+
+int prepare_net_ns(int pid)
+{
+	return -1;
+}