commit 9bfaf4fe66b40eb8f9def5a6ff96aa6b9da80782
author Eric W. Biederman <ebiederm@xmission.com> Wed Sep 02 14:51:14 2015 +0530
committer Swetha Chikkaboraiah <schikk@codeaurora.org> Fri Sep 11 14:34:08 2015 +0530
tree 13f23c5d67a516bd68186e25d4f61c3aaa371ce9
parent 474fc3ec7e1a3f543d80809daea8bc14a7ec7a5e

vfs: Add a user namespace reference from struct mnt_namespace

This will allow for support for unprivileged mounts in a new user namespace.

Change-Id: I861716cf94da385c1805edcc9b43209a9d491b69
Acked-by: "Serge E. Hallyn" <serge@hallyn.com>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Git-commit: ef2fbdef5dea4621c5a889a46e12526511c8610b
Git-repo: https://android.googlesource.com/kernel/common/
[schikk@codeaurora.org: Resolved merge conflicts ]
CRs-Fixed: 901628
Signed-off-by: Swetha Chikkaboraiah <schikk@codeaurora.org>

fs/namespace.c

diff --git a/fs/namespace.c b/fs/namespace.c
index 9d486b7..12c9b3d 100644
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -12,6 +12,7 @@
 #include <linux/export.h>
 #include <linux/capability.h>
 #include <linux/mnt_namespace.h>
+#include <linux/user_namespace.h>
 #include <linux/namei.h>
 #include <linux/security.h>
 #include <linux/idr.h>
@@ -2217,6 +2218,13 @@
 	return retval;
 }
 
+
+static void free_mnt_ns(struct mnt_namespace *ns)
+{
+	put_user_ns(ns->user_ns);
+	kfree(ns);
+}
+
 /*
  * Assign a sequence number so we can detect when we attempt to bind
  * mount a reference to an older mount namespace into the current
@@ -2226,7 +2234,7 @@
  */
 static atomic64_t mnt_ns_seq = ATOMIC64_INIT(1);
 
-static struct mnt_namespace *alloc_mnt_ns(void)
+static struct mnt_namespace *alloc_mnt_ns(struct user_namespace *user_ns)
 {
 	struct mnt_namespace *new_ns;
 
@@ -2239,6 +2247,7 @@
 	INIT_LIST_HEAD(&new_ns->list);
 	init_waitqueue_head(&new_ns->poll);
 	new_ns->event = 0;
+	new_ns->user_ns = get_user_ns(user_ns);
 	return new_ns;
 }
 
@@ -2264,7 +2273,7 @@
  * copied from the namespace of the passed in task structure.
  */
 static struct mnt_namespace *dup_mnt_ns(struct mnt_namespace *mnt_ns,
-		struct fs_struct *fs)
+		struct user_namespace *user_ns, struct fs_struct *fs)
 {
 	struct mnt_namespace *new_ns;
 	struct vfsmount *rootmnt = NULL, *pwdmnt = NULL;
@@ -2272,7 +2281,7 @@
 	struct mount *old = mnt_ns->root;
 	struct mount *new;
 
-	new_ns = alloc_mnt_ns();
+	new_ns = alloc_mnt_ns(user_ns);
 	if (IS_ERR(new_ns))
 		return new_ns;
 
@@ -2281,7 +2290,7 @@
 	new = copy_tree(old, old->mnt.mnt_root, CL_COPY_ALL | CL_EXPIRE);
 	if (!new) {
 		up_write(&namespace_sem);
-		kfree(new_ns);
+		free_mnt_ns(new_ns);
 		return ERR_PTR(-ENOMEM);
 	}
 	new_ns->root = new;
@@ -2327,7 +2336,7 @@
 }
 
 struct mnt_namespace *copy_mnt_ns(unsigned long flags, struct mnt_namespace *ns,
-		struct fs_struct *new_fs)
+		 struct user_namespace *user_ns, struct fs_struct *new_fs)
 {
 	struct mnt_namespace *new_ns;
 
@@ -2337,7 +2346,7 @@
 	if (!(flags & CLONE_NEWNS))
 		return ns;
 
-	new_ns = dup_mnt_ns(ns, new_fs);
+	new_ns = dup_mnt_ns(ns, user_ns, new_fs);
 
 	put_mnt_ns(ns);
 	return new_ns;
@@ -2349,7 +2358,7 @@
  */
 static struct mnt_namespace *create_mnt_ns(struct vfsmount *m)
 {
-	struct mnt_namespace *new_ns = alloc_mnt_ns();
+	struct mnt_namespace *new_ns = alloc_mnt_ns(&init_user_ns);
 	if (!IS_ERR(new_ns)) {
 		struct mount *mnt = real_mount(m);
 		mnt->mnt_ns = new_ns;
@@ -2636,7 +2645,7 @@
 	br_write_unlock(vfsmount_lock);
 	up_write(&namespace_sem);
 	release_mounts(&umount_list);
-	kfree(ns);
+	free_mnt_ns(ns);
 }
 
 struct vfsmount *kern_mount_data(struct file_system_type *type, void *data)