From patchwork Tue May 26 18:53:14 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Greg Kroah-Hartman X-Patchwork-Id: 225409 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.8 required=3.0 tests=DKIMWL_WL_HIGH, DKIM_SIGNED, DKIM_VALID, HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI, SIGNED_OFF_BY, SPF_HELO_NONE, SPF_PASS, USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 0CAFAC433E2 for ; Tue, 26 May 2020 18:59:07 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id DFF50208B3 for ; Tue, 26 May 2020 18:59:06 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1590519546; bh=4xrfH+sv45WGOsOPPbPW3FK1rvunu9p+Fl83Nkco5cI=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=Nc7NU7iyW9k0Rtz0sVm4Mb27s9llhvLrz9pRu6r47jFVzZTrF9qwKS+NBcDHnRn++ aD4yFjJvHN4qnfevakzRl/jLezAxVaZay6y/D5KuWj1fyKj+5345cNnktv7ytf2NK+ akfh0JoX1UuSHAb+zqOVPTveC6BuzH8Yj7utm7iQ= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2390454AbgEZS7F (ORCPT ); Tue, 26 May 2020 14:59:05 -0400 Received: from mail.kernel.org ([198.145.29.99]:52696 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2390457AbgEZS7D (ORCPT ); Tue, 26 May 2020 14:59:03 -0400 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 8D17820849; Tue, 26 May 2020 18:59:02 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1590519543; bh=4xrfH+sv45WGOsOPPbPW3FK1rvunu9p+Fl83Nkco5cI=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=W0moH9Ed4IqiDAKB400pLUE/JoYnYfYtyUNp+MNKK8F+qq66n5EGSvmr3lrCkOrO6 fNcp0UB+AMkJIstBdT+xltQBnhOcxEI1qdhbczi9Gl7lE6VCiN0FW8aKvsYl+D7MzR OYIxveQ415pKRI/DfwQZer+devGYIQNUvJSq4NbY= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org, greg@kroah.com Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Guillaume Nault , "David S. Miller" , Giuliano Procida Subject: [PATCH 4.9 45/64] l2tp: dont register sessions in l2tp_session_create() Date: Tue, 26 May 2020 20:53:14 +0200 Message-Id: <20200526183928.528073757@linuxfoundation.org> X-Mailer: git-send-email 2.26.2 In-Reply-To: <20200526183913.064413230@linuxfoundation.org> References: <20200526183913.064413230@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Guillaume Nault commit 3953ae7b218df4d1e544b98a393666f9ae58a78c upstream. Sessions created by l2tp_session_create() aren't fully initialised: some pseudo-wire specific operations need to be done before making the session usable. Therefore the PPP and Ethernet pseudo-wires continue working on the returned l2tp session while it's already been exposed to the rest of the system. This can lead to various issues. In particular, the session may enter the deletion process before having been fully initialised, which will confuse the session removal code. This patch moves session registration out of l2tp_session_create(), so that callers can control when the session is exposed to the rest of the system. This is done by the new l2tp_session_register() function. Only pppol2tp_session_create() can be easily converted to avoid modifying its session after registration (the debug message is dropped in order to avoid the need for holding a reference on the session). For pppol2tp_connect() and l2tp_eth_create()), more work is needed. That'll be done in followup patches. For now, let's just register the session right after its creation, like it was done before. The only difference is that we can easily take a reference on the session before registering it, so, at least, we're sure it's not going to be freed while we're working on it. Signed-off-by: Guillaume Nault Signed-off-by: David S. Miller Signed-off-by: Giuliano Procida Signed-off-by: Greg Kroah-Hartman --- net/l2tp/l2tp_core.c | 21 +++++++-------------- net/l2tp/l2tp_core.h | 3 +++ net/l2tp/l2tp_eth.c | 9 +++++++++ net/l2tp/l2tp_ppp.c | 27 +++++++++++++++++++-------- 4 files changed, 38 insertions(+), 22 deletions(-) --- a/net/l2tp/l2tp_core.c +++ b/net/l2tp/l2tp_core.c @@ -321,8 +321,8 @@ struct l2tp_session *l2tp_session_get_by } EXPORT_SYMBOL_GPL(l2tp_session_get_by_ifname); -static int l2tp_session_add_to_tunnel(struct l2tp_tunnel *tunnel, - struct l2tp_session *session) +int l2tp_session_register(struct l2tp_session *session, + struct l2tp_tunnel *tunnel) { struct l2tp_session *session_walk; struct hlist_head *g_head; @@ -370,6 +370,10 @@ static int l2tp_session_add_to_tunnel(st hlist_add_head(&session->hlist, head); write_unlock_bh(&tunnel->hlist_lock); + /* Ignore management session in session count value */ + if (session->session_id != 0) + atomic_inc(&l2tp_session_count); + return 0; err_tlock_pnlock: @@ -379,6 +383,7 @@ err_tlock: return err; } +EXPORT_SYMBOL_GPL(l2tp_session_register); /* Lookup a tunnel by id */ @@ -1788,7 +1793,6 @@ EXPORT_SYMBOL_GPL(l2tp_session_set_heade struct l2tp_session *l2tp_session_create(int priv_size, struct l2tp_tunnel *tunnel, u32 session_id, u32 peer_session_id, struct l2tp_session_cfg *cfg) { struct l2tp_session *session; - int err; session = kzalloc(sizeof(struct l2tp_session) + priv_size, GFP_KERNEL); if (session != NULL) { @@ -1845,17 +1849,6 @@ struct l2tp_session *l2tp_session_create l2tp_session_inc_refcount(session); - err = l2tp_session_add_to_tunnel(tunnel, session); - if (err) { - kfree(session); - - return ERR_PTR(err); - } - - /* Ignore management session in session count value */ - if (session->session_id != 0) - atomic_inc(&l2tp_session_count); - return session; } --- a/net/l2tp/l2tp_core.h +++ b/net/l2tp/l2tp_core.h @@ -259,6 +259,9 @@ struct l2tp_session *l2tp_session_create struct l2tp_tunnel *tunnel, u32 session_id, u32 peer_session_id, struct l2tp_session_cfg *cfg); +int l2tp_session_register(struct l2tp_session *session, + struct l2tp_tunnel *tunnel); + void __l2tp_session_unhash(struct l2tp_session *session); int l2tp_session_delete(struct l2tp_session *session); void l2tp_session_free(struct l2tp_session *session); --- a/net/l2tp/l2tp_eth.c +++ b/net/l2tp/l2tp_eth.c @@ -267,6 +267,13 @@ static int l2tp_eth_create(struct net *n goto out; } + l2tp_session_inc_refcount(session); + rc = l2tp_session_register(session, tunnel); + if (rc < 0) { + kfree(session); + goto out; + } + dev = alloc_netdev(sizeof(*priv), name, NET_NAME_UNKNOWN, l2tp_eth_dev_setup); if (!dev) { @@ -298,6 +305,7 @@ static int l2tp_eth_create(struct net *n __module_get(THIS_MODULE); /* Must be done after register_netdev() */ strlcpy(session->ifname, dev->name, IFNAMSIZ); + l2tp_session_dec_refcount(session); dev_hold(dev); @@ -308,6 +316,7 @@ out_del_dev: spriv->dev = NULL; out_del_session: l2tp_session_delete(session); + l2tp_session_dec_refcount(session); out: return rc; } --- a/net/l2tp/l2tp_ppp.c +++ b/net/l2tp/l2tp_ppp.c @@ -722,6 +722,14 @@ static int pppol2tp_connect(struct socke error = PTR_ERR(session); goto end; } + + l2tp_session_inc_refcount(session); + error = l2tp_session_register(session, tunnel); + if (error < 0) { + kfree(session); + goto end; + } + drop_refcnt = true; } /* Associate session with its PPPoL2TP socket */ @@ -807,7 +815,7 @@ static int pppol2tp_session_create(struc /* Error if tunnel socket is not prepped */ if (!tunnel->sock) { error = -ENOENT; - goto out; + goto err; } /* Default MTU values. */ @@ -822,18 +830,21 @@ static int pppol2tp_session_create(struc peer_session_id, cfg); if (IS_ERR(session)) { error = PTR_ERR(session); - goto out; + goto err; } ps = l2tp_session_priv(session); ps->tunnel_sock = tunnel->sock; - l2tp_info(session, L2TP_MSG_CONTROL, "%s: created\n", - session->name); - - error = 0; - -out: + error = l2tp_session_register(session, tunnel); + if (error < 0) + goto err_sess; + + return 0; + +err_sess: + kfree(session); +err: return error; }