[Devel] [patch -mm 3/4] add pid_namespace to nsproxy

[Cedric Le Goater]

Add a notion of pid namespace to nsproxy (and by extension, to task_struct).
Currently there is only one pid namespace, init_pid_ns and all tasks belong
to this pid namespace. When a new task is created, it inherits its parent's
pid namespace (in copy_process()).

This is based on Eric Biederman's patch: http://lkml.org/lkml/2006/2/6/285

Signed-off-by: Sukadev Bhattiprolu <sukadev at us.ibm.com>
Signed-off-by: Cedric Le Goater <clg at fr.ibm.com>
Cc: Eric Biederman <ebiederm at xmission.com>
Cc: Dave Hansen <haveblue at us.ibm.com>
Cc: Serge Hallyn <serue at us.ibm.com>
Cc: containers at lists.osdl.org

 include/linux/init_task.h     |    2 ++
 include/linux/nsproxy.h       |    2 ++
 include/linux/pid_namespace.h |   15 +++++++++++++++
 kernel/nsproxy.c              |   12 ++++++++++++
 4 files changed, 31 insertions(+)

Index: 2.6.18-rc6-mm1/include/linux/init_task.h
===================================================================
--- 2.6.18-rc6-mm1.orig/include/linux/init_task.h
+++ 2.6.18-rc6-mm1/include/linux/init_task.h
@@ -7,6 +7,7 @@
 #include <linux/utsname.h>
 #include <linux/lockdep.h>
 #include <linux/ipc.h>
+#include <linux/pid_namespace.h>
 
 #define INIT_FDTABLE \
 {							\
@@ -72,6 +73,7 @@
 
 extern struct nsproxy init_nsproxy;
 #define INIT_NSPROXY(nsproxy) {						\
+	.pid_ns		= &init_pid_ns,					\
 	.count		= ATOMIC_INIT(1),				\
 	.nslock		= SPIN_LOCK_UNLOCKED,				\
 	.uts_ns		= &init_uts_ns,					\
Index: 2.6.18-rc6-mm1/include/linux/nsproxy.h
===================================================================
--- 2.6.18-rc6-mm1.orig/include/linux/nsproxy.h
+++ 2.6.18-rc6-mm1/include/linux/nsproxy.h
@@ -7,6 +7,7 @@
 struct mnt_namespace;
 struct uts_namespace;
 struct ipc_namespace;
+struct pid_namespace;
 
 /*
  * A structure to contain pointers to all per-process
@@ -23,6 +24,7 @@ struct ipc_namespace;
 struct nsproxy {
 	atomic_t count;
 	spinlock_t nslock;
+	struct pid_namespace *pid_ns;
 	struct uts_namespace *uts_ns;
 	struct ipc_namespace *ipc_ns;
 	struct mnt_namespace *mnt_ns;
Index: 2.6.18-rc6-mm1/include/linux/pid_namespace.h
===================================================================
--- 2.6.18-rc6-mm1.orig/include/linux/pid_namespace.h
+++ 2.6.18-rc6-mm1/include/linux/pid_namespace.h
@@ -5,6 +5,7 @@
 #include <linux/mm.h>
 #include <linux/threads.h>
 #include <linux/pid.h>
+#include <linux/nsproxy.h>
 
 struct pidmap {
        atomic_t nr_free;
@@ -20,4 +21,18 @@ struct pid_namespace {
 
 extern struct pid_namespace init_pid_ns;
 
+static inline void get_pid_ns(struct pid_namespace *ns)
+{
+}
+
+static inline int copy_pid_ns(int flags, struct task_struct *tsk)
+{
+	tsk->nsproxy->pid_ns = &init_pid_ns;
+	return 0;
+}
+
+static inline void put_pid_ns(struct pid_namespace *ns)
+{
+}
+
 #endif /* _LINUX_PID_NS_H */
Index: 2.6.18-rc6-mm1/kernel/nsproxy.c
===================================================================
--- 2.6.18-rc6-mm1.orig/kernel/nsproxy.c
+++ 2.6.18-rc6-mm1/kernel/nsproxy.c
@@ -19,6 +19,7 @@
 #include <linux/init_task.h>
 #include <linux/mnt_namespace.h>
 #include <linux/utsname.h>
+#include <linux/pid_namespace.h>
 
 struct nsproxy init_nsproxy = INIT_NSPROXY(init_nsproxy);
 
@@ -68,6 +69,8 @@ struct nsproxy *dup_namespaces(struct ns
 			get_uts_ns(ns->uts_ns);
 		if (ns->ipc_ns)
 			get_ipc_ns(ns->ipc_ns);
+		if (ns->pid_ns)
+			get_pid_ns(ns->pid_ns);
 	}
 
 	return ns;
@@ -111,10 +114,17 @@ int copy_namespaces(int flags, struct ta
 	if (err)
 		goto out_ipc;
 
+	err = copy_pid_ns(flags, tsk);
+	if (err)
+		goto out_pid;
+
 out:
 	put_nsproxy(old_ns);
 	return err;
 
+out_pid:
+	if (new_ns->ipc_ns)
+		put_ipc_ns(new_ns->ipc_ns);
 out_ipc:
 	if (new_ns->uts_ns)
 		put_uts_ns(new_ns->uts_ns);
@@ -135,5 +145,7 @@ void free_nsproxy(struct nsproxy *ns)
 			put_uts_ns(ns->uts_ns);
 		if (ns->ipc_ns)
 			put_ipc_ns(ns->ipc_ns);
+		if (ns->pid_ns)
+			put_pid_ns(ns->pid_ns);
 		kfree(ns);
 }

--
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