This patch allows you to create a new network namespace
using sys_clone, or sys_unshare.
As the network namespace is still experimental and under development
clone and unshare support is only made available when CONFIG_NET_NS is
selected at compile time.
As this patch introduces network namespace support into code paths
that exist when the CONFIG_NET is not selected there are a few
additions made to net_namespace.h to allow a few more functions
to be used when the networking stack is not compiled in.
Signed-off-by: Eric W. Biederman <[EMAIL PROTECTED]>
---
include/linux/sched.h | 1 +
include/net/net_namespace.h | 18 ++++++++++++++++++
kernel/fork.c | 3 ++-
kernel/nsproxy.c | 15 +++++++++++++--
net/Kconfig | 8 ++++++++
net/core/net_namespace.c | 43 +++++++++++++++++++++++++++++++++++++++++--
6 files changed, 83 insertions(+), 5 deletions(-)
diff --git a/include/linux/sched.h b/include/linux/sched.h
index a01ac6d..e10a0a8 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -27,6 +27,7 @@
#define CLONE_NEWUTS 0x04000000 /* New utsname group? */
#define CLONE_NEWIPC 0x08000000 /* New ipcs */
#define CLONE_NEWUSER 0x10000000 /* New user namespace */
+#define CLONE_NEWNET 0x20000000 /* New network namespace */
/*
* Scheduling policies
diff --git a/include/net/net_namespace.h b/include/net/net_namespace.h
index ac8f830..3ea4194 100644
--- a/include/net/net_namespace.h
+++ b/include/net/net_namespace.h
@@ -38,11 +38,23 @@ extern struct net init_net;
extern struct list_head net_namespace_list;
+#ifdef CONFIG_NET
+extern struct net *copy_net_ns(unsigned long flags, struct net *net_ns);
+#else
+static inline struct net *copy_net_ns(unsigned long flags, struct net *net_ns)
+{
+ /* There is nothing to copy so this is a noop */
+ return net_ns;
+}
+#endif
+
extern void __put_net(struct net *net);
static inline struct net *get_net(struct net *net)
{
+#ifdef CONFIG_NET
atomic_inc(&net->count);
+#endif
return net;
}
@@ -60,19 +72,25 @@ static inline struct net *maybe_get_net(struct net *net)
static inline void put_net(struct net *net)
{
+#ifdef CONFIG_NET
if (atomic_dec_and_test(&net->count))
__put_net(net);
+#endif
}
static inline struct net *hold_net(struct net *net)
{
+#ifdef CONFIG_NET
atomic_inc(&net->use_count);
+#endif
return net;
}
static inline void release_net(struct net *net)
{
+#ifdef CONFIG_NET
atomic_dec(&net->use_count);
+#endif
}
extern void net_lock(void);
diff --git a/kernel/fork.c b/kernel/fork.c
index 33f12f4..5e67f90 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -1608,7 +1608,8 @@ asmlinkage long sys_unshare(unsigned long unshare_flags)
err = -EINVAL;
if (unshare_flags & ~(CLONE_THREAD|CLONE_FS|CLONE_NEWNS|CLONE_SIGHAND|
CLONE_VM|CLONE_FILES|CLONE_SYSVSEM|
- CLONE_NEWUTS|CLONE_NEWIPC|CLONE_NEWUSER))
+ CLONE_NEWUTS|CLONE_NEWIPC|CLONE_NEWUSER|
+ CLONE_NEWNET))
goto bad_unshare_out;
if ((err = unshare_thread(unshare_flags)))
diff --git a/kernel/nsproxy.c b/kernel/nsproxy.c
index a4fb7d4..f1decd2 100644
--- a/kernel/nsproxy.c
+++ b/kernel/nsproxy.c
@@ -20,6 +20,7 @@
#include <linux/mnt_namespace.h>
#include <linux/utsname.h>
#include <linux/pid_namespace.h>
+#include <net/net_namespace.h>
static struct kmem_cache *nsproxy_cachep;
@@ -98,8 +99,17 @@ static struct nsproxy *create_new_namespaces(unsigned long
flags,
goto out_user;
}
+ new_nsp->net_ns = copy_net_ns(flags, tsk->nsproxy->net_ns);
+ if (IS_ERR(new_nsp->net_ns)) {
+ err = PTR_ERR(new_nsp->net_ns);
+ goto out_net;
+ }
+
return new_nsp;
+out_net:
+ if (new_nsp->user_ns)
+ put_user_ns(new_nsp->user_ns);
out_user:
if (new_nsp->pid_ns)
put_pid_ns(new_nsp->pid_ns);
@@ -132,7 +142,7 @@ int copy_namespaces(unsigned long flags, struct task_struct
*tsk)
get_nsproxy(old_ns);
- if (!(flags & (CLONE_NEWNS | CLONE_NEWUTS | CLONE_NEWIPC |
CLONE_NEWUSER)))
+ if (!(flags & (CLONE_NEWNS | CLONE_NEWUTS | CLONE_NEWIPC |
CLONE_NEWUSER | CLONE_NEWNET)))
return 0;
if (!capable(CAP_SYS_ADMIN)) {
@@ -164,6 +174,7 @@ void free_nsproxy(struct nsproxy *ns)
put_pid_ns(ns->pid_ns);
if (ns->user_ns)
put_user_ns(ns->user_ns);
+ put_net(ns->net_ns);
kmem_cache_free(nsproxy_cachep, ns);
}
@@ -177,7 +188,7 @@ int unshare_nsproxy_namespaces(unsigned long unshare_flags,
int err = 0;
if (!(unshare_flags & (CLONE_NEWNS | CLONE_NEWUTS | CLONE_NEWIPC |
- CLONE_NEWUSER)))
+ CLONE_NEWUSER | CLONE_NEWNET)))
return 0;
if (!capable(CAP_SYS_ADMIN))
diff --git a/net/Kconfig b/net/Kconfig
index cdba08c..ab4e6da 100644
--- a/net/Kconfig
+++ b/net/Kconfig
@@ -27,6 +27,14 @@ if NET
menu "Networking options"
+config NET_NS
+ bool "Network namespace support"
+ default n
+ depends on EXPERIMENTAL && !SYSFS
+ help
+ Allow user space to create what appear to be multiple instances
+ of the network stack.
+
source "net/packet/Kconfig"
source "net/unix/Kconfig"
source "net/xfrm/Kconfig"
diff --git a/net/core/net_namespace.c b/net/core/net_namespace.c
index 0e6cb02..e478e35 100644
--- a/net/core/net_namespace.c
+++ b/net/core/net_namespace.c
@@ -4,6 +4,7 @@
#include <linux/slab.h>
#include <linux/list.h>
#include <linux/delay.h>
+#include <linux/sched.h>
#include <net/net_namespace.h>
/*
@@ -32,12 +33,10 @@ void net_unlock(void)
mutex_unlock(&net_list_mutex);
}
-#if 0
static struct net *net_alloc(void)
{
return kmem_cache_alloc(net_cachep, GFP_KERNEL);
}
-#endif
static void net_free(struct net *net)
{
@@ -128,6 +127,46 @@ out_undo:
goto out;
}
+struct net *copy_net_ns(unsigned long flags, struct net *old_net)
+{
+ struct net *new_net = NULL;
+ int err;
+
+ get_net(old_net);
+
+ if (!(flags & CLONE_NEWNET))
+ return old_net;
+
+#ifndef CONFIG_NET_NS
+ return ERR_PTR(-EINVAL);
+#endif
+
+ err = -ENOMEM;
+ new_net = net_alloc();
+ if (!new_net)
+ goto out;
+
+ mutex_lock(&net_mutex);
+ err = setup_net(new_net);
+ if (err)
+ goto out_unlock;
+
+ net_lock();
+ list_add_tail(&new_net->list, &net_namespace_list);
+ net_unlock();
+
+
+out_unlock:
+ mutex_unlock(&net_mutex);
+out:
+ put_net(old_net);
+ if (err) {
+ net_free(new_net);
+ new_net = ERR_PTR(err);
+ }
+ return new_net;
+}
+
static int __init net_ns_init(void)
{
int err;
--
1.5.3.rc6.17.g1911
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