audit: ignore fcaps on umount

Don't fetch fcaps when umount2 is called to avoid a process hang while
it waits for the missing resource to (possibly never) re-appear.

Note the comment above user_path_mountpoint_at():
 * A umount is a special case for path walking. We're not actually interested
 * in the inode in this situation, and ESTALE errors can be a problem.  We
 * simply want track down the dentry and vfsmount attached at the mountpoint
 * and avoid revalidating the last component.

This can happen on ceph, cifs, 9p, lustre, fuse (gluster) or NFS.

Please see the github issue tracker
https://github.com/linux-audit/audit-kernel/issues/100

Signed-off-by: Richard Guy Briggs <rgb@redhat.com>
[PM: merge fuzz in audit_log_fcaps()]
Signed-off-by: Paul Moore <paul@paul-moore.com>
diff --git a/kernel/auditsc.c b/kernel/auditsc.c
index a2696ce..68da710 100644
--- a/kernel/auditsc.c
+++ b/kernel/auditsc.c
@@ -1856,7 +1856,7 @@ void __audit_inode(struct filename *name, const struct dentry *dentry,
 		n->type = AUDIT_TYPE_NORMAL;
 	}
 	handle_path(dentry);
-	audit_copy_inode(n, dentry, inode);
+	audit_copy_inode(n, dentry, inode, flags & AUDIT_INODE_NOEVAL);
 }
 
 void __audit_file(const struct file *file)
@@ -1955,7 +1955,7 @@ void __audit_inode_child(struct inode *parent,
 		n = audit_alloc_name(context, AUDIT_TYPE_PARENT);
 		if (!n)
 			return;
-		audit_copy_inode(n, NULL, parent);
+		audit_copy_inode(n, NULL, parent, 0);
 	}
 
 	if (!found_child) {
@@ -1974,7 +1974,7 @@ void __audit_inode_child(struct inode *parent,
 	}
 
 	if (inode)
-		audit_copy_inode(found_child, dentry, inode);
+		audit_copy_inode(found_child, dentry, inode, 0);
 	else
 		found_child->ino = AUDIT_INO_UNSET;
 }