btrfs: properly track when rescan worker is running

[mirror_ubuntu-zesty-kernel.git] / fs / namespace.c

diff --git a/fs/namespace.c b/fs/namespace.c
index 0570729c87fd22dd299c50ee0303f43c384e4932..936393978fdaa16ddbb1a970abaf58f866a37b4f 100644 (file)
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -463,6 +463,7 @@ void __mnt_drop_write(struct vfsmount *mnt)
        mnt_dec_writers(real_mount(mnt));
        preempt_enable();
 }
+EXPORT_SYMBOL_GPL(__mnt_drop_write);
 
 /**
  * mnt_drop_write - give up write access to a mount
@@ -1510,7 +1511,7 @@ static int do_umount(struct mount *mnt, int flags)
                 * Special case for "unmounting" root ...
                 * we just try to remount it readonly.
                 */
-               if (!capable(CAP_SYS_ADMIN))
+               if (!ns_capable(sb->s_user_ns, CAP_SYS_ADMIN))
                        return -EPERM;
                down_write(&sb->s_umount);
                if (!(sb->s_flags & MS_RDONLY))
@@ -1562,6 +1563,7 @@ void __detach_mounts(struct dentry *dentry)
                goto out_unlock;
 
        lock_mount_hash();
+       event++;
        while (!hlist_empty(&mp->m_list)) {
                mnt = hlist_entry(mp->m_list.first, struct mount, mnt_mp_list);
                if (mnt->mnt.mnt_flags & MNT_UMOUNT) {
@@ -1803,6 +1805,7 @@ int iterate_mounts(int (*f)(struct vfsmount *, void *), void *arg,
        }
        return 0;
 }
+EXPORT_SYMBOL(iterate_mounts);
 
 static void cleanup_group_ids(struct mount *mnt, struct mount *end)
 {
@@ -2205,7 +2208,7 @@ static int do_remount(struct path *path, int flags, int mnt_flags,
        down_write(&sb->s_umount);
        if (flags & MS_BIND)
                err = change_mount_flags(path->mnt, flags);
-       else if (!capable(CAP_SYS_ADMIN))
+       else if (!ns_capable(sb->s_user_ns, CAP_SYS_ADMIN))
                err = -EPERM;
        else
                err = do_remount_sb(sb, flags, data, 0);
@@ -2381,6 +2384,9 @@ static int do_new_mount(struct path *path, const char *fstype, int flags,
        struct vfsmount *mnt;
        int err;
 
+       if (!ns_capable(current_user_ns(), CAP_SYS_ADMIN))
+               return -EPERM;
+
        if (!fstype)
                return -EINVAL;
 
@@ -2401,8 +2407,10 @@ static int do_new_mount(struct path *path, const char *fstype, int flags,
                        mnt_flags |= MNT_NODEV | MNT_LOCK_NODEV;
                }
                if (type->fs_flags & FS_USERNS_VISIBLE) {
-                       if (!fs_fully_visible(type, &mnt_flags))
+                       if (!fs_fully_visible(type, &mnt_flags)) {
+                               put_filesystem(type);
                                return -EPERM;
+                       }
                }
        }
 
@@ -3236,6 +3244,10 @@ static bool fs_fully_visible(struct file_system_type *type, int *new_mnt_flags)
                if (mnt->mnt.mnt_sb->s_iflags & SB_I_NOEXEC)
                        mnt_flags &= ~(MNT_LOCK_NOSUID | MNT_LOCK_NOEXEC);
 
+               /* Don't miss readonly hidden in the superblock flags */
+               if (mnt->mnt.mnt_sb->s_flags & MS_RDONLY)
+                       mnt_flags |= MNT_LOCK_READONLY;
+
                /* Verify the mount flags are equal to or more permissive
                 * than the proposed new mount.
                 */
@@ -3262,7 +3274,7 @@ static bool fs_fully_visible(struct file_system_type *type, int *new_mnt_flags)
                list_for_each_entry(child, &mnt->mnt_mounts, mnt_child) {
                        struct inode *inode = child->mnt_mountpoint->d_inode;
                        /* Only worry about locked mounts */
-                       if (!(mnt_flags & MNT_LOCKED))
+                       if (!(child->mnt.mnt_flags & MNT_LOCKED))
                                continue;
                        /* Is the directory permanetly empty? */
                        if (!is_empty_dir_inode(inode))
@@ -3283,6 +3295,19 @@ found:
        return visible;
 }
 
+bool mnt_may_suid(struct vfsmount *mnt)
+{
+       /*
+        * Foreign mounts (accessed via fchdir or through /proc
+        * symlinks) are always treated as if they are nosuid.  This
+        * prevents namespaces from trusting potentially unsafe
+        * suid/sgid bits, file caps, or security labels that originate
+        * in other namespaces.
+        */
+       return !(mnt->mnt_flags & MNT_NOSUID) && check_mnt(real_mount(mnt)) &&
+              current_in_userns(mnt->mnt_sb->s_user_ns);
+}
+
 static struct ns_common *mntns_get(struct task_struct *task)
 {
        struct ns_common *ns = NULL;