27 files changed, 196 insertions, 2 deletions

diff --git a/arch/alpha/kernel/init_task.c b/arch/alpha/kernel/init_task.c
index 835d09a7b332..83d09021ed97 100644
--- a/arch/alpha/kernel/init_task.c
+++ b/arch/alpha/kernel/init_task.c
@@ -5,6 +5,7 @@
 #include <linux/init_task.h>
 #include <linux/fs.h>
 #include <linux/mqueue.h>
+#include <linux/nsproxy.h>
 #include <asm/uaccess.h>
 
 
@@ -13,6 +14,7 @@ static struct files_struct init_files = INIT_FILES;
 static struct signal_struct init_signals = INIT_SIGNALS(init_signals);
 static struct sighand_struct init_sighand = INIT_SIGHAND(init_sighand);
 struct mm_struct init_mm = INIT_MM(init_mm);
+struct nsproxy init_nsproxy = INIT_NSPROXY(init_nsproxy);
 struct task_struct init_task = INIT_TASK(init_task);
 
 EXPORT_SYMBOL(init_mm);
diff --git a/arch/arm/kernel/init_task.c b/arch/arm/kernel/init_task.c
index a00cca0000bd..80f5eeb6d3a8 100644
--- a/arch/arm/kernel/init_task.c
+++ b/arch/arm/kernel/init_task.c
@@ -8,6 +8,7 @@
 #include <linux/init.h>
 #include <linux/init_task.h>
 #include <linux/mqueue.h>
+#include <linux/nsproxy.h>
 
 #include <asm/uaccess.h>
 #include <asm/pgtable.h>
@@ -17,6 +18,7 @@ static struct files_struct init_files = INIT_FILES;
 static struct signal_struct init_signals = INIT_SIGNALS(init_signals);
 static struct sighand_struct init_sighand = INIT_SIGHAND(init_sighand);
 struct mm_struct init_mm = INIT_MM(init_mm);
+struct nsproxy init_nsproxy = INIT_NSPROXY(init_nsproxy);
 
 EXPORT_SYMBOL(init_mm);
 
diff --git a/arch/arm26/kernel/init_task.c b/arch/arm26/kernel/init_task.c
index 4191565b889b..678c7b57f9c7 100644
--- a/arch/arm26/kernel/init_task.c
+++ b/arch/arm26/kernel/init_task.c
@@ -11,6 +11,7 @@
 #include <linux/init.h>
 #include <linux/init_task.h>
 #include <linux/mqueue.h>
+#include <linux/nsproxy.h>
 
 #include <asm/uaccess.h>
 #include <asm/pgtable.h>
@@ -20,6 +21,7 @@ static struct files_struct init_files = INIT_FILES;
 static struct signal_struct init_signals = INIT_SIGNALS(init_signals);
 static struct sighand_struct init_sighand = INIT_SIGHAND(init_sighand);
 struct mm_struct init_mm = INIT_MM(init_mm);
+struct nsproxy init_nsproxy = INIT_NSPROXY(init_nsproxy);
 
 EXPORT_SYMBOL(init_mm);
 
diff --git a/arch/frv/kernel/init_task.c b/arch/frv/kernel/init_task.c
index 22993932b3fc..5ec27422bfe3 100644
--- a/arch/frv/kernel/init_task.c
+++ b/arch/frv/kernel/init_task.c
@@ -5,6 +5,7 @@
 #include <linux/init_task.h>
 #include <linux/fs.h>
 #include <linux/mqueue.h>
+#include <linux/nsproxy.h>
 
 #include <asm/uaccess.h>
 #include <asm/pgtable.h>
@@ -15,6 +16,7 @@ static struct files_struct init_files = INIT_FILES;
 static struct signal_struct init_signals = INIT_SIGNALS(init_signals);
 static struct sighand_struct init_sighand = INIT_SIGHAND(init_sighand);
 struct mm_struct init_mm = INIT_MM(init_mm);
+struct nsproxy init_nsproxy = INIT_NSPROXY(init_nsproxy);
 
 EXPORT_SYMBOL(init_mm);
 
diff --git a/arch/h8300/kernel/init_task.c b/arch/h8300/kernel/init_task.c
index 19272c2ac56a..ef5755af6e28 100644
--- a/arch/h8300/kernel/init_task.c
+++ b/arch/h8300/kernel/init_task.c
@@ -8,6 +8,7 @@
 #include <linux/init_task.h>
 #include <linux/fs.h>
 #include <linux/mqueue.h>
+#include <linux/nsproxy.h>
 
 #include <asm/uaccess.h>
 #include <asm/pgtable.h>
@@ -17,6 +18,7 @@ static struct files_struct init_files = INIT_FILES;
 static struct signal_struct init_signals = INIT_SIGNALS(init_signals);
 static struct sighand_struct init_sighand = INIT_SIGHAND(init_sighand);
 struct mm_struct init_mm = INIT_MM(init_mm);
+struct nsproxy init_nsproxy = INIT_NSPROXY(init_nsproxy);
 
 EXPORT_SYMBOL(init_mm);
 
diff --git a/arch/i386/kernel/init_task.c b/arch/i386/kernel/init_task.c
index cff95d10a4d8..bd97f69ac34f 100644
--- a/arch/i386/kernel/init_task.c
+++ b/arch/i386/kernel/init_task.c
@@ -5,6 +5,7 @@
 #include <linux/init_task.h>
 #include <linux/fs.h>
 #include <linux/mqueue.h>
+#include <linux/nsproxy.h>
 
 #include <asm/uaccess.h>
 #include <asm/pgtable.h>
@@ -15,6 +16,7 @@ static struct files_struct init_files = INIT_FILES;
 static struct signal_struct init_signals = INIT_SIGNALS(init_signals);
 static struct sighand_struct init_sighand = INIT_SIGHAND(init_sighand);
 struct mm_struct init_mm = INIT_MM(init_mm);
+struct nsproxy init_nsproxy = INIT_NSPROXY(init_nsproxy);
 
 EXPORT_SYMBOL(init_mm);
 
diff --git a/arch/ia64/kernel/init_task.c b/arch/ia64/kernel/init_task.c
index b69c397ed1bf..2d62471bfd02 100644
--- a/arch/ia64/kernel/init_task.c
+++ b/arch/ia64/kernel/init_task.c
@@ -12,6 +12,7 @@
 #include <linux/sched.h>
 #include <linux/init_task.h>
 #include <linux/mqueue.h>
+#include <linux/nsproxy.h>
 
 #include <asm/uaccess.h>
 #include <asm/pgtable.h>
@@ -21,6 +22,7 @@ static struct files_struct init_files = INIT_FILES;
 static struct signal_struct init_signals = INIT_SIGNALS(init_signals);
 static struct sighand_struct init_sighand = INIT_SIGHAND(init_sighand);
 struct mm_struct init_mm = INIT_MM(init_mm);
+struct nsproxy init_nsproxy = INIT_NSPROXY(init_nsproxy);
 
 EXPORT_SYMBOL(init_mm);
 
diff --git a/arch/m32r/kernel/init_task.c b/arch/m32r/kernel/init_task.c
index 9e508fd9d970..005747590da6 100644
--- a/arch/m32r/kernel/init_task.c
+++ b/arch/m32r/kernel/init_task.c
@@ -7,6 +7,7 @@
 #include <linux/init_task.h>
 #include <linux/fs.h>
 #include <linux/mqueue.h>
+#include <linux/nsproxy.h>
 
 #include <asm/uaccess.h>
 #include <asm/pgtable.h>
@@ -16,6 +17,7 @@ static struct files_struct init_files = INIT_FILES;
 static struct signal_struct init_signals = INIT_SIGNALS(init_signals);
 static struct sighand_struct init_sighand = INIT_SIGHAND(init_sighand);
 struct mm_struct init_mm = INIT_MM(init_mm);
+struct nsproxy init_nsproxy = INIT_NSPROXY(init_nsproxy);
 
 EXPORT_SYMBOL(init_mm);
 
diff --git a/arch/m68knommu/kernel/init_task.c b/arch/m68knommu/kernel/init_task.c
index 3897043a126a..b99fc6d6b7c1 100644
--- a/arch/m68knommu/kernel/init_task.c
+++ b/arch/m68knommu/kernel/init_task.c
@@ -8,6 +8,7 @@
 #include <linux/init_task.h>
 #include <linux/fs.h>
 #include <linux/mqueue.h>
+#include <linux/nsproxy.h>
 
 #include <asm/uaccess.h>
 #include <asm/pgtable.h>
@@ -17,6 +18,7 @@ static struct files_struct init_files = INIT_FILES;
 static struct signal_struct init_signals = INIT_SIGNALS(init_signals);
 static struct sighand_struct init_sighand = INIT_SIGHAND(init_sighand);
 struct mm_struct init_mm = INIT_MM(init_mm);
+struct nsproxy init_nsproxy = INIT_NSPROXY(init_nsproxy);
 
 EXPORT_SYMBOL(init_mm);
 
diff --git a/arch/mips/kernel/init_task.c b/arch/mips/kernel/init_task.c
index aeda7f58391b..dfe47e6a8b37 100644
--- a/arch/mips/kernel/init_task.c
+++ b/arch/mips/kernel/init_task.c
@@ -4,6 +4,7 @@
 #include <linux/init_task.h>
 #include <linux/fs.h>
 #include <linux/mqueue.h>
+#include <linux/nsproxy.h>
 
 #include <asm/thread_info.h>
 #include <asm/uaccess.h>
@@ -14,6 +15,7 @@ static struct files_struct init_files = INIT_FILES;
 static struct signal_struct init_signals = INIT_SIGNALS(init_signals);
 static struct sighand_struct init_sighand = INIT_SIGHAND(init_sighand);
 struct mm_struct init_mm = INIT_MM(init_mm);
+struct nsproxy init_nsproxy = INIT_NSPROXY(init_nsproxy);
 
 EXPORT_SYMBOL(init_mm);
 
diff --git a/arch/parisc/kernel/init_task.c b/arch/parisc/kernel/init_task.c
index 8384bf9cecd2..c0c43e29973b 100644
--- a/arch/parisc/kernel/init_task.c
+++ b/arch/parisc/kernel/init_task.c
@@ -28,6 +28,7 @@
 #include <linux/init.h>
 #include <linux/init_task.h>
 #include <linux/mqueue.h>
+#include <linux/nsproxy.h>
 
 #include <asm/uaccess.h>
 #include <asm/pgtable.h>
@@ -38,6 +39,7 @@ static struct files_struct init_files = INIT_FILES;
 static struct signal_struct init_signals = INIT_SIGNALS(init_signals);
 static struct sighand_struct init_sighand = INIT_SIGHAND(init_sighand);
 struct mm_struct init_mm = INIT_MM(init_mm);
+struct nsproxy init_nsproxy = INIT_NSPROXY(init_nsproxy);
 
 EXPORT_SYMBOL(init_mm);
 
diff --git a/arch/powerpc/kernel/init_task.c b/arch/powerpc/kernel/init_task.c
index 941043ae040f..e24ace618987 100644
--- a/arch/powerpc/kernel/init_task.c
+++ b/arch/powerpc/kernel/init_task.c
@@ -5,6 +5,7 @@
 #include <linux/init_task.h>
 #include <linux/fs.h>
 #include <linux/mqueue.h>
+#include <linux/nsproxy.h>
 #include <asm/uaccess.h>
 
 static struct fs_struct init_fs = INIT_FS;
@@ -12,6 +13,7 @@ static struct files_struct init_files = INIT_FILES;
 static struct signal_struct init_signals = INIT_SIGNALS(init_signals);
 static struct sighand_struct init_sighand = INIT_SIGHAND(init_sighand);
 struct mm_struct init_mm = INIT_MM(init_mm);
+struct nsproxy init_nsproxy = INIT_NSPROXY(init_nsproxy);
 
 EXPORT_SYMBOL(init_mm);
 
diff --git a/arch/s390/kernel/init_task.c b/arch/s390/kernel/init_task.c
index d73a74013e73..0918921763b1 100644
--- a/arch/s390/kernel/init_task.c
+++ b/arch/s390/kernel/init_task.c
@@ -11,6 +11,7 @@
 #include <linux/sched.h>
 #include <linux/init_task.h>
 #include <linux/mqueue.h>
+#include <linux/nsproxy.h>
 
 #include <asm/uaccess.h>
 #include <asm/pgtable.h>
@@ -20,6 +21,7 @@ static struct files_struct init_files = INIT_FILES;
 static struct signal_struct init_signals = INIT_SIGNALS(init_signals);
 static struct sighand_struct init_sighand = INIT_SIGHAND(init_sighand);
 struct mm_struct init_mm = INIT_MM(init_mm);
+struct nsproxy init_nsproxy = INIT_NSPROXY(init_nsproxy);
 
 EXPORT_SYMBOL(init_mm);
 
diff --git a/arch/sh/kernel/init_task.c b/arch/sh/kernel/init_task.c
index 44053ea92936..81caf0fd3bee 100644
--- a/arch/sh/kernel/init_task.c
+++ b/arch/sh/kernel/init_task.c
@@ -3,6 +3,7 @@
 #include <linux/sched.h>
 #include <linux/init_task.h>
 #include <linux/mqueue.h>
+#include <linux/nsproxy.h>
 
 #include <asm/uaccess.h>
 #include <asm/pgtable.h>
@@ -12,6 +13,7 @@ static struct files_struct init_files = INIT_FILES;
 static struct signal_struct init_signals = INIT_SIGNALS(init_signals);
 static struct sighand_struct init_sighand = INIT_SIGHAND(init_sighand);
 struct mm_struct init_mm = INIT_MM(init_mm);
+struct nsproxy init_nsproxy = INIT_NSPROXY(init_nsproxy);
 
 EXPORT_SYMBOL(init_mm);
 
diff --git a/arch/sh64/kernel/init_task.c b/arch/sh64/kernel/init_task.c
index de2d07db1f88..0c95f40c5403 100644
--- a/arch/sh64/kernel/init_task.c
+++ b/arch/sh64/kernel/init_task.c
@@ -14,6 +14,7 @@
 #include <linux/sched.h>
 #include <linux/init_task.h>
 #include <linux/mqueue.h>
+#include <linux/nsproxy.h>
 
 #include <asm/uaccess.h>
 #include <asm/pgtable.h>
@@ -23,6 +24,7 @@ static struct files_struct init_files = INIT_FILES;
 static struct signal_struct init_signals = INIT_SIGNALS(init_signals);
 static struct sighand_struct init_sighand = INIT_SIGHAND(init_sighand);
 struct mm_struct init_mm = INIT_MM(init_mm);
+struct nsproxy init_nsproxy = INIT_NSPROXY(init_nsproxy);
 
 struct pt_regs fake_swapper_regs;
 
diff --git a/arch/sparc/kernel/init_task.c b/arch/sparc/kernel/init_task.c
index fc31de66b1c2..a73926d5176b 100644
--- a/arch/sparc/kernel/init_task.c
+++ b/arch/sparc/kernel/init_task.c
@@ -3,6 +3,7 @@
 #include <linux/sched.h>
 #include <linux/init_task.h>
 #include <linux/mqueue.h>
+#include <linux/nsproxy.h>
 
 #include <asm/pgtable.h>
 #include <asm/uaccess.h>
@@ -12,6 +13,7 @@ static struct files_struct init_files = INIT_FILES;
 static struct signal_struct init_signals = INIT_SIGNALS(init_signals);
 static struct sighand_struct init_sighand = INIT_SIGHAND(init_sighand);
 struct mm_struct init_mm = INIT_MM(init_mm);
+struct nsproxy init_nsproxy = INIT_NSPROXY(init_nsproxy);
 struct task_struct init_task = INIT_TASK(init_task);
 
 EXPORT_SYMBOL(init_mm);
diff --git a/arch/sparc64/kernel/init_task.c b/arch/sparc64/kernel/init_task.c
index 329b38fa5c89..f1e9a4b021ae 100644
--- a/arch/sparc64/kernel/init_task.c
+++ b/arch/sparc64/kernel/init_task.c
@@ -3,6 +3,7 @@
 #include <linux/sched.h>
 #include <linux/init_task.h>
 #include <linux/mqueue.h>
+#include <linux/nsproxy.h>
 
 #include <asm/pgtable.h>
 #include <asm/uaccess.h>
@@ -13,6 +14,7 @@ static struct files_struct init_files = INIT_FILES;
 static struct signal_struct init_signals = INIT_SIGNALS(init_signals);
 static struct sighand_struct init_sighand = INIT_SIGHAND(init_sighand);
 struct mm_struct init_mm = INIT_MM(init_mm);
+struct nsproxy init_nsproxy = INIT_NSPROXY(init_nsproxy);
 
 EXPORT_SYMBOL(init_mm);
 
diff --git a/arch/um/kernel/init_task.c b/arch/um/kernel/init_task.c
index 49ed5ddf0704..11188af64d86 100644
--- a/arch/um/kernel/init_task.c
+++ b/arch/um/kernel/init_task.c
@@ -9,6 +9,7 @@
 #include "linux/sched.h"
 #include "linux/init_task.h"
 #include "linux/mqueue.h"
+#include "linux/nsproxy.h"
 #include "asm/uaccess.h"
 #include "asm/pgtable.h"
 #include "user_util.h"
@@ -17,6 +18,7 @@
 
 static struct fs_struct init_fs = INIT_FS;
 struct mm_struct init_mm = INIT_MM(init_mm);
+struct nsproxy init_nsproxy = INIT_NSPROXY(init_nsproxy);
 static struct files_struct init_files = INIT_FILES;
 static struct signal_struct init_signals = INIT_SIGNALS(init_signals);
 static struct sighand_struct init_sighand = INIT_SIGHAND(init_sighand);
diff --git a/arch/v850/kernel/init_task.c b/arch/v850/kernel/init_task.c
index ed2f93cf7c66..9d2de7590849 100644
--- a/arch/v850/kernel/init_task.c
+++ b/arch/v850/kernel/init_task.c
@@ -16,6 +16,7 @@
 #include <linux/init_task.h>
 #include <linux/fs.h>
 #include <linux/mqueue.h>
+#include <linux/nsproxy.h>
 
 #include <asm/uaccess.h>
 #include <asm/pgtable.h>
@@ -25,6 +26,7 @@ static struct files_struct init_files = INIT_FILES;
 static struct signal_struct init_signals = INIT_SIGNALS (init_signals);
 static struct sighand_struct init_sighand = INIT_SIGHAND(init_sighand);
 struct mm_struct init_mm = INIT_MM (init_mm);
+struct nsproxy init_nsproxy = INIT_NSPROXY(init_nsproxy);
 
 EXPORT_SYMBOL(init_mm);
 
diff --git a/arch/x86_64/kernel/init_task.c b/arch/x86_64/kernel/init_task.c
index 3dc5854ba21e..879728bff73f 100644
--- a/arch/x86_64/kernel/init_task.c
+++ b/arch/x86_64/kernel/init_task.c
@@ -5,6 +5,7 @@
 #include <linux/init_task.h>
 #include <linux/fs.h>
 #include <linux/mqueue.h>
+#include <linux/nsproxy.h>
 
 #include <asm/uaccess.h>
 #include <asm/pgtable.h>
@@ -15,6 +16,7 @@ static struct files_struct init_files = INIT_FILES;
 static struct signal_struct init_signals = INIT_SIGNALS(init_signals);
 static struct sighand_struct init_sighand = INIT_SIGHAND(init_sighand);
 struct mm_struct init_mm = INIT_MM(init_mm);
+struct nsproxy init_nsproxy = INIT_NSPROXY(init_nsproxy);
 
 EXPORT_SYMBOL(init_mm);
 
diff --git a/include/linux/init_task.h b/include/linux/init_task.h
index 60aac2cea0cf..8f8bb422a5c7 100644
--- a/include/linux/init_task.h
+++ b/include/linux/init_task.h
@@ -68,6 +68,12 @@
         .session        = 1,                                            \
 }
 
+extern struct nsproxy init_nsproxy;
+#define INIT_NSPROXY(nsproxy) {                                         \
+        .count          = ATOMIC_INIT(1),                               \
+        .nslock         = SPIN_LOCK_UNLOCKED,                           \
+}
+
 #define INIT_SIGHAND(sighand) {                                         \
         .count          = ATOMIC_INIT(1),                               \
         .action         = { { { .sa_handler = NULL, } }, },             \
@@ -117,6 +123,7 @@ extern struct group_info init_groups;
         .files          = &init_files,                                  \
         .signal         = &init_signals,                                \
         .sighand        = &init_sighand,                                \
+        .nsproxy        = &init_nsproxy,                                \
         .pending        = {                                             \
                 .list = LIST_HEAD_INIT(tsk.pending.list),               \
                 .signal = {{0}}},                                       \
diff --git a/include/linux/nsproxy.h b/include/linux/nsproxy.h
new file mode 100644
index 000000000000..7bdebfaab6a5
--- /dev/null
+++ b/include/linux/nsproxy.h
@@ -0,0 +1,45 @@
+#ifndef _LINUX_NSPROXY_H
+#define _LINUX_NSPROXY_H
+
+#include <linux/spinlock.h>
+#include <linux/sched.h>
+
+/*
+ * A structure to contain pointers to all per-process
+ * namespaces - fs (mount), uts, network, sysvipc, etc.
+ *
+ * 'count' is the number of tasks holding a reference.
+ * The count for each namespace, then, will be the number
+ * of nsproxies pointing to it, not the number of tasks.
+ *
+ * The nsproxy is shared by tasks which share all namespaces.
+ * As soon as a single namespace is cloned or unshared, the
+ * nsproxy is copied.
+ */
+struct nsproxy {
+        atomic_t count;
+        spinlock_t nslock;
+};
+extern struct nsproxy init_nsproxy;
+
+struct nsproxy *dup_namespaces(struct nsproxy *orig);
+int copy_namespaces(int flags, struct task_struct *tsk);
+void get_task_namespaces(struct task_struct *tsk);
+void free_nsproxy(struct nsproxy *ns);
+
+static inline void put_nsproxy(struct nsproxy *ns)
+{
+        if (atomic_dec_and_test(&ns->count)) {
+                free_nsproxy(ns);
+        }
+}
+
+static inline void exit_task_namespaces(struct task_struct *p)
+{
+        struct nsproxy *ns = p->nsproxy;
+        if (ns) {
+                put_nsproxy(ns);
+                p->nsproxy = NULL;
+        }
+}
+#endif
diff --git a/include/linux/sched.h b/include/linux/sched.h
index a7fff3304bd6..4fa631fa55e3 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -239,6 +239,7 @@ extern signed long schedule_timeout_uninterruptible(signed long timeout);
 asmlinkage void schedule(void);
 
 struct namespace;
+struct nsproxy;
 
 /* Maximum number of active map areas.. This is a random (large) number */
 #define DEFAULT_MAX_MAP_COUNT   65536
@@ -898,6 +899,7 @@ struct task_struct {
         struct files_struct *files;
 /* namespace */
         struct namespace *namespace;
+        struct nsproxy *nsproxy;
 /* signal handlers */
         struct signal_struct *signal;
         struct sighand_struct *sighand;
diff --git a/kernel/Makefile b/kernel/Makefile
index aacaafb28b9d..6ec53009b866 100644
--- a/kernel/Makefile
+++ b/kernel/Makefile
@@ -8,7 +8,7 @@ obj-y     = sched.o fork.o exec_domain.o panic.o printk.o profile.o \
             signal.o sys.o kmod.o workqueue.o pid.o \
             rcupdate.o extable.o params.o posix-timers.o \
             kthread.o wait.o kfifo.o sys_ni.o posix-cpu-timers.o mutex.o \
-            hrtimer.o rwsem.o latency.o
+            hrtimer.o rwsem.o latency.o nsproxy.o
 
 obj-$(CONFIG_STACKTRACE) += stacktrace.o
 obj-y += time/
diff --git a/kernel/exit.c b/kernel/exit.c
index 3b47f26985f2..1d0e9ea1fa05 100644
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -21,6 +21,7 @@
 #include <linux/tsacct_kern.h>
 #include <linux/file.h>
 #include <linux/binfmts.h>
+#include <linux/nsproxy.h>
 #include <linux/ptrace.h>
 #include <linux/profile.h>
 #include <linux/mount.h>
@@ -397,9 +398,14 @@ void daemonize(const char *name, ...)
         fs = init_task.fs;
         current->fs = fs;
         atomic_inc(&fs->count);
+
         exit_namespace(current);
+        exit_task_namespaces(current);
         current->namespace = init_task.namespace;
+        current->nsproxy = init_task.nsproxy;
         get_namespace(current->namespace);
+        get_task_namespaces(current);
+
         exit_files(current);
         current->files = init_task.files;
         atomic_inc(&current->files->count);
@@ -918,6 +924,7 @@ fastcall NORET_TYPE void do_exit(long code)
         __exit_files(tsk);
         __exit_fs(tsk);
         exit_namespace(tsk);
+        exit_task_namespaces(tsk);
         exit_thread();
         cpuset_exit(tsk);
         exit_keys(tsk);
diff --git a/kernel/fork.c b/kernel/fork.c
index 89f666491d1f..c9e660ae47aa 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -27,6 +27,7 @@
 #include <linux/binfmts.h>
 #include <linux/mman.h>
 #include <linux/fs.h>
+#include <linux/nsproxy.h>
 #include <linux/capability.h>
 #include <linux/cpu.h>
 #include <linux/cpuset.h>
@@ -1116,8 +1117,10 @@ static struct task_struct *copy_process(unsigned long clone_flags,
                 goto bad_fork_cleanup_signal;
         if ((retval = copy_keys(clone_flags, p)))
                 goto bad_fork_cleanup_mm;
-        if ((retval = copy_namespace(clone_flags, p)))
+        if ((retval = copy_namespaces(clone_flags, p)))
                 goto bad_fork_cleanup_keys;
+        if ((retval = copy_namespace(clone_flags, p)))
+                goto bad_fork_cleanup_namespaces;
         retval = copy_thread(0, clone_flags, stack_start, stack_size, p, regs);
         if (retval)
                 goto bad_fork_cleanup_namespace;
@@ -1262,6 +1265,8 @@ static struct task_struct *copy_process(unsigned long clone_flags,
 
 bad_fork_cleanup_namespace:
         exit_namespace(p);
+bad_fork_cleanup_namespaces:
+        exit_task_namespaces(p);
 bad_fork_cleanup_keys:
         exit_keys(p);
 bad_fork_cleanup_mm:
@@ -1606,6 +1611,7 @@ asmlinkage long sys_unshare(unsigned long unshare_flags)
         struct mm_struct *mm, *new_mm = NULL, *active_mm = NULL;
         struct files_struct *fd, *new_fd = NULL;
         struct sem_undo_list *new_ulist = NULL;
+        struct nsproxy *new_nsproxy, *old_nsproxy;
 
         check_unshare_flags(&unshare_flags);
 
@@ -1632,7 +1638,15 @@ asmlinkage long sys_unshare(unsigned long unshare_flags)
 
         if (new_fs || new_ns || new_sigh || new_mm || new_fd || new_ulist) {
 
+                old_nsproxy = current->nsproxy;
+                new_nsproxy = dup_namespaces(old_nsproxy);
+                if (!new_nsproxy) {
+                        err = -ENOMEM;
+                        goto bad_unshare_cleanup_semundo;
+                }
+
                 task_lock(current);
+                current->nsproxy = new_nsproxy;
 
                 if (new_fs) {
                         fs = current->fs;
@@ -1668,8 +1682,10 @@ asmlinkage long sys_unshare(unsigned long unshare_flags)
                 }
 
                 task_unlock(current);
+                put_nsproxy(old_nsproxy);
         }
 
+bad_unshare_cleanup_semundo:
 bad_unshare_cleanup_fd:
         if (new_fd)
                 put_files_struct(new_fd);
diff --git a/kernel/nsproxy.c b/kernel/nsproxy.c
new file mode 100644
index 000000000000..ad9508865473
--- /dev/null
+++ b/kernel/nsproxy.c
@@ -0,0 +1,77 @@
+/*
+ *  Copyright (C) 2006 IBM Corporation
+ *
+ *  Author: Serge Hallyn <serue@us.ibm.com>
+ *
+ *  This program is free software; you can redistribute it and/or
+ *  modify it under the terms of the GNU General Public License as
+ *  published by the Free Software Foundation, version 2 of the
+ *  License.
+ */
+
+#include <linux/module.h>
+#include <linux/version.h>
+#include <linux/nsproxy.h>
+
+static inline void get_nsproxy(struct nsproxy *ns)
+{
+        atomic_inc(&ns->count);
+}
+
+void get_task_namespaces(struct task_struct *tsk)
+{
+        struct nsproxy *ns = tsk->nsproxy;
+        if (ns) {
+                get_nsproxy(ns);
+        }
+}
+
+/*
+ * creates a copy of "orig" with refcount 1.
+ * This does not grab references to the contained namespaces,
+ * so that needs to be done by dup_namespaces.
+ */
+static inline struct nsproxy *clone_namespaces(struct nsproxy *orig)
+{
+        struct nsproxy *ns;
+
+        ns = kmalloc(sizeof(struct nsproxy), GFP_KERNEL);
+        if (ns) {
+                memcpy(ns, orig, sizeof(struct nsproxy));
+                atomic_set(&ns->count, 1);
+        }
+        return ns;
+}
+
+/*
+ * copies the nsproxy, setting refcount to 1, and grabbing a
+ * reference to all contained namespaces.  Called from
+ * sys_unshare()
+ */
+struct nsproxy *dup_namespaces(struct nsproxy *orig)
+{
+        struct nsproxy *ns = clone_namespaces(orig);
+
+        return ns;
+}
+
+/*
+ * called from clone.  This now handles copy for nsproxy and all
+ * namespaces therein.
+ */
+int copy_namespaces(int flags, struct task_struct *tsk)
+{
+        struct nsproxy *old_ns = tsk->nsproxy;
+
+        if (!old_ns)
+                return 0;
+
+        get_nsproxy(old_ns);
+
+        return 0;
+}
+
+void free_nsproxy(struct nsproxy *ns)
+{
+                kfree(ns);
+}