Subject: [PATCH 4/8] ns proc: Add support for the uts namespace

From: [email-masked] (Eric W. Biederman)
Date: Thu, 23 Sep 2010 01:48:22 -0700

Signed-off-by: Eric W. Biederman <[email-masked]>
---
 fs/proc/namespaces.c    |    3 +++
 include/linux/proc_fs.h |    1 +
 kernel/utsname.c        |   32 ++++++++++++++++++++++++++++++++
 3 files changed, 36 insertions(+), 0 deletions(-)

diff --git a/fs/proc/namespaces.c b/fs/proc/namespaces.c
index 31e32f3..902443e 100644
--- a/fs/proc/namespaces.c
+++ b/fs/proc/namespaces.c
@@ -19,6 +19,9 @@ static const struct proc_ns_operations *ns_entries[] = {
 #ifdef CONFIG_NET_NS
 	&netns_operations,
 #endif
+#ifdef CONFIG_UTS_NS
+	&utsns_operations,
+#endif
 };
 
 static const struct file_operations ns_file_operations = {
diff --git a/include/linux/proc_fs.h b/include/linux/proc_fs.h
index 9cd3fae..28b4ffd 100644
--- a/include/linux/proc_fs.h
+++ b/include/linux/proc_fs.h
@@ -263,6 +263,7 @@ struct proc_ns_operations {
 };
 #define PROC_NSNAME(NAME) { .name = (NAME), .len = (sizeof(NAME) - 1), }
 extern const struct proc_ns_operations netns_operations;
+extern const struct proc_ns_operations utsns_operations;
 extern struct file *proc_ns_fget(int fd);
 
 union proc_op {
diff --git a/kernel/utsname.c b/kernel/utsname.c
index 8a82b4b..ff06086 100644
--- a/kernel/utsname.c
+++ b/kernel/utsname.c
@@ -14,6 +14,7 @@
 #include <linux/utsname.h>
 #include <linux/err.h>
 #include <linux/slab.h>
+#include <linux/proc_fs.h>
 
 static struct uts_namespace *create_uts_ns(void)
 {
@@ -73,3 +74,34 @@ void free_uts_ns(struct kref *kref)
 	ns = container_of(kref, struct uts_namespace, kref);
 	kfree(ns);
 }
+
+static void *utsns_get(struct task_struct *task)
+{
+	struct uts_namespace *ns;
+	rcu_read_lock();
+	ns = task->nsproxy->uts_ns;
+	get_uts_ns(ns);
+	rcu_read_unlock();
+	return ns;
+}
+
+static void utsns_put(void *ns)
+{
+	put_uts_ns(ns);
+}
+
+static int utsns_install(struct nsproxy *nsproxy, void *ns)
+{
+	get_uts_ns(ns);
+	put_uts_ns(nsproxy->uts_ns);
+	nsproxy->uts_ns = ns;
+	return 0;
+}
+
+const struct proc_ns_operations utsns_operations = {
+	.name		= PROC_NSNAME("uts"),
+	.get		= utsns_get,
+	.put		= utsns_put,
+	.install	= utsns_install,
+};
+
-- 
1.6.5.2.143.g8cc62