Isolate the UTS namespace's domainname and hostname back

Commit 7d69a1f4a72b18876c99c697692b78339d491568 ("remove CONFIG_UTS_NS
and CONFIG_IPC_NS") by Cedric Le Goater accidentally removed the code
that prevented the uts->hostname and uts->domainname values from being
overwritten from another namespace.

In other words, setting hostname/domainname via sysfs (echo xxx >
/proc/sys/kernel/(host|domain)name) cased the new value to be set in
init UTS namespace only.

Return the isolation back.

Signed-off-by: Pavel Emelyanov <xemul@openvz.org>
Acked-by: Cedric Le Goater <clg@fr.ibm.com>
Acked-by: Serge Hallyn <serue@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 4 insertions, 0 deletions

diff --git a/kernel/utsname_sysctl.c b/kernel/utsname_sysctl.c
index c76c06466bf..fe3a56c2256 100644
--- a/kernel/utsname_sysctl.c
+++ b/kernel/utsname_sysctl.c
@@ -18,6 +18,10 @@
 static void *get_uts(ctl_table *table, int write)
 {
         char *which = table->data;
+        struct uts_namespace *uts_ns;
+
+        uts_ns = current->nsproxy->uts_ns;
+        which = (which - (char *)&init_uts_ns) + (char *)uts_ns;
 
         if (!write)
                 down_read(&uts_sem);