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-rw-r--r--kernel/utsname.c53
1 files changed, 53 insertions, 0 deletions
diff --git a/kernel/utsname.c b/kernel/utsname.c
index 1824384ecfa3..c859164a6993 100644
--- a/kernel/utsname.c
+++ b/kernel/utsname.c
@@ -15,6 +15,41 @@
#include <linux/version.h>
/*
+ * Clone a new ns copying an original utsname, setting refcount to 1
+ * @old_ns: namespace to clone
+ * Return NULL on error (failure to kmalloc), new ns otherwise
+ */
+static struct uts_namespace *clone_uts_ns(struct uts_namespace *old_ns)
+{
+ struct uts_namespace *ns;
+
+ ns = kmalloc(sizeof(struct uts_namespace), GFP_KERNEL);
+ if (ns) {
+ memcpy(&ns->name, &old_ns->name, sizeof(ns->name));
+ kref_init(&ns->kref);
+ }
+ return ns;
+}
+
+/*
+ * unshare the current process' utsname namespace.
+ * called only in sys_unshare()
+ */
+int unshare_utsname(unsigned long unshare_flags, struct uts_namespace **new_uts)
+{
+ if (unshare_flags & CLONE_NEWUTS) {
+ if (!capable(CAP_SYS_ADMIN))
+ return -EPERM;
+
+ *new_uts = clone_uts_ns(current->nsproxy->uts_ns);
+ if (!*new_uts)
+ return -ENOMEM;
+ }
+
+ return 0;
+}
+
+/*
* Copy task tsk's utsname namespace, or clone it if flags
* specifies CLONE_NEWUTS. In latter case, changes to the
* utsname of this process won't be seen by parent, and vice
@@ -23,6 +58,7 @@
int copy_utsname(int flags, struct task_struct *tsk)
{
struct uts_namespace *old_ns = tsk->nsproxy->uts_ns;
+ struct uts_namespace *new_ns;
int err = 0;
if (!old_ns)
@@ -30,6 +66,23 @@ int copy_utsname(int flags, struct task_struct *tsk)
get_uts_ns(old_ns);
+ if (!(flags & CLONE_NEWUTS))
+ return 0;
+
+ if (!capable(CAP_SYS_ADMIN)) {
+ err = -EPERM;
+ goto out;
+ }
+
+ new_ns = clone_uts_ns(old_ns);
+ if (!new_ns) {
+ err = -ENOMEM;
+ goto out;
+ }
+ tsk->nsproxy->uts_ns = new_ns;
+
+out:
+ put_uts_ns(old_ns);
return err;
}