Merge branch 'next' of git://git.kernel.org/pub/scm/linux/kernel/git/scottwood/linux.git

[firefly-linux-kernel-4.4.55.git] / fs / namespace.c

diff --git a/fs/namespace.c b/fs/namespace.c
index be3f6f23a47dc0650747e8cc6ad851c22eff56c0..ef42d9bee2121f8e6a68937a5ecaa7670721ded9 100644 (file)
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -783,7 +783,7 @@ static void attach_shadowed(struct mount *mnt,
                        struct mount *shadows)
 {
        if (shadows) {
-               hlist_add_after_rcu(&shadows->mnt_hash, &mnt->mnt_hash);
+               hlist_add_behind_rcu(&mnt->mnt_hash, &shadows->mnt_hash);
                list_add(&mnt->mnt_child, &shadows->mnt_child);
        } else {
                hlist_add_head_rcu(&mnt->mnt_hash,
@@ -898,8 +898,21 @@ static struct mount *clone_mnt(struct mount *old, struct dentry *root,
 
        mnt->mnt.mnt_flags = old->mnt.mnt_flags & ~(MNT_WRITE_HOLD|MNT_MARKED);
        /* Don't allow unprivileged users to change mount flags */
-       if ((flag & CL_UNPRIVILEGED) && (mnt->mnt.mnt_flags & MNT_READONLY))
-               mnt->mnt.mnt_flags |= MNT_LOCK_READONLY;
+       if (flag & CL_UNPRIVILEGED) {
+               mnt->mnt.mnt_flags |= MNT_LOCK_ATIME;
+
+               if (mnt->mnt.mnt_flags & MNT_READONLY)
+                       mnt->mnt.mnt_flags |= MNT_LOCK_READONLY;
+
+               if (mnt->mnt.mnt_flags & MNT_NODEV)
+                       mnt->mnt.mnt_flags |= MNT_LOCK_NODEV;
+
+               if (mnt->mnt.mnt_flags & MNT_NOSUID)
+                       mnt->mnt.mnt_flags |= MNT_LOCK_NOSUID;
+
+               if (mnt->mnt.mnt_flags & MNT_NOEXEC)
+                       mnt->mnt.mnt_flags |= MNT_LOCK_NOEXEC;
+       }
 
        /* Don't allow unprivileged users to reveal what is under a mount */
        if ((flag & CL_UNPRIVILEGED) && list_empty(&old->mnt_expire))
@@ -1204,6 +1217,11 @@ static void namespace_unlock(void)
        head.first->pprev = &head.first;
        INIT_HLIST_HEAD(&unmounted);
 
+       /* undo decrements we'd done in umount_tree() */
+       hlist_for_each_entry(mnt, &head, mnt_hash)
+               if (mnt->mnt_ex_mountpoint.mnt)
+                       mntget(mnt->mnt_ex_mountpoint.mnt);
+
        up_write(&namespace_sem);
 
        synchronize_rcu();
@@ -1240,6 +1258,9 @@ void umount_tree(struct mount *mnt, int how)
                hlist_add_head(&p->mnt_hash, &tmp_list);
        }
 
+       hlist_for_each_entry(p, &tmp_list, mnt_hash)
+               list_del_init(&p->mnt_child);
+
        if (how)
                propagate_umount(&tmp_list);
 
@@ -1250,9 +1271,9 @@ void umount_tree(struct mount *mnt, int how)
                p->mnt_ns = NULL;
                if (how < 2)
                        p->mnt.mnt_flags |= MNT_SYNC_UMOUNT;
-               list_del_init(&p->mnt_child);
                if (mnt_has_parent(p)) {
                        put_mountpoint(p->mnt_mp);
+                       mnt_add_count(p->mnt_parent, -1);
                        /* move the reference to mountpoint into ->mnt_ex_mountpoint */
                        p->mnt_ex_mountpoint.dentry = p->mnt_mountpoint;
                        p->mnt_ex_mountpoint.mnt = &p->mnt_parent->mnt;
@@ -1895,9 +1916,6 @@ static int change_mount_flags(struct vfsmount *mnt, int ms_flags)
        if (readonly_request == __mnt_is_readonly(mnt))
                return 0;
 
-       if (mnt->mnt_flags & MNT_LOCK_READONLY)
-               return -EPERM;
-
        if (readonly_request)
                error = mnt_make_readonly(real_mount(mnt));
        else
@@ -1923,6 +1941,33 @@ static int do_remount(struct path *path, int flags, int mnt_flags,
        if (path->dentry != path->mnt->mnt_root)
                return -EINVAL;
 
+       /* Don't allow changing of locked mnt flags.
+        *
+        * No locks need to be held here while testing the various
+        * MNT_LOCK flags because those flags can never be cleared
+        * once they are set.
+        */
+       if ((mnt->mnt.mnt_flags & MNT_LOCK_READONLY) &&
+           !(mnt_flags & MNT_READONLY)) {
+               return -EPERM;
+       }
+       if ((mnt->mnt.mnt_flags & MNT_LOCK_NODEV) &&
+           !(mnt_flags & MNT_NODEV)) {
+               return -EPERM;
+       }
+       if ((mnt->mnt.mnt_flags & MNT_LOCK_NOSUID) &&
+           !(mnt_flags & MNT_NOSUID)) {
+               return -EPERM;
+       }
+       if ((mnt->mnt.mnt_flags & MNT_LOCK_NOEXEC) &&
+           !(mnt_flags & MNT_NOEXEC)) {
+               return -EPERM;
+       }
+       if ((mnt->mnt.mnt_flags & MNT_LOCK_ATIME) &&
+           ((mnt->mnt.mnt_flags & MNT_ATIME_MASK) != (mnt_flags & MNT_ATIME_MASK))) {
+               return -EPERM;
+       }
+
        err = security_sb_remount(sb, data);
        if (err)
                return err;
@@ -1936,7 +1981,7 @@ static int do_remount(struct path *path, int flags, int mnt_flags,
                err = do_remount_sb(sb, flags, data, 0);
        if (!err) {
                lock_mount_hash();
-               mnt_flags |= mnt->mnt.mnt_flags & MNT_PROPAGATION_MASK;
+               mnt_flags |= mnt->mnt.mnt_flags & ~MNT_USER_SETTABLE_MASK;
                mnt->mnt.mnt_flags = mnt_flags;
                touch_mnt_namespace(mnt->mnt_ns);
                unlock_mount_hash();
@@ -2121,7 +2166,7 @@ static int do_new_mount(struct path *path, const char *fstype, int flags,
                 */
                if (!(type->fs_flags & FS_USERNS_DEV_MOUNT)) {
                        flags |= MS_NODEV;
-                       mnt_flags |= MNT_NODEV;
+                       mnt_flags |= MNT_NODEV | MNT_LOCK_NODEV;
                }
        }
 
@@ -2435,6 +2480,14 @@ long do_mount(const char *dev_name, const char *dir_name,
        if (flags & MS_RDONLY)
                mnt_flags |= MNT_READONLY;
 
+       /* The default atime for remount is preservation */
+       if ((flags & MS_REMOUNT) &&
+           ((flags & (MS_NOATIME | MS_NODIRATIME | MS_RELATIME |
+                      MS_STRICTATIME)) == 0)) {
+               mnt_flags &= ~MNT_ATIME_MASK;
+               mnt_flags |= path.mnt->mnt_flags & MNT_ATIME_MASK;
+       }
+
        flags &= ~(MS_NOSUID | MS_NOEXEC | MS_NODEV | MS_ACTIVE | MS_BORN |
                   MS_NOATIME | MS_NODIRATIME | MS_RELATIME| MS_KERNMOUNT |
                   MS_STRICTATIME);
@@ -2971,13 +3024,13 @@ static void *mntns_get(struct task_struct *task)
        struct mnt_namespace *ns = NULL;
        struct nsproxy *nsproxy;
 
-       rcu_read_lock();
-       nsproxy = task_nsproxy(task);
+       task_lock(task);
+       nsproxy = task->nsproxy;
        if (nsproxy) {
                ns = nsproxy->mnt_ns;
                get_mnt_ns(ns);
        }
-       rcu_read_unlock();
+       task_unlock(task);
 
        return ns;
 }