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[2620:137:e000::1:20]) by mx.google.com with ESMTP id v22-20020a636116000000b00502fdd175f3si11226697pgb.148.2023.04.16.17.55.48; Sun, 16 Apr 2023 17:56:00 -0700 (PDT) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20; Authentication-Results: mx.google.com; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229883AbjDPWHL (ORCPT + 99 others); Sun, 16 Apr 2023 18:07:11 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:34332 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229494AbjDPWHJ (ORCPT ); Sun, 16 Apr 2023 18:07:09 -0400 Received: from sonata.ens-lyon.org (sonata.ens-lyon.org [140.77.166.138]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 9E19F211C; Sun, 16 Apr 2023 15:07:07 -0700 (PDT) Received: from localhost (localhost [127.0.0.1]) by sonata.ens-lyon.org (Postfix) with ESMTP id 684102018B; Mon, 17 Apr 2023 00:07:04 +0200 (CEST) Received: from sonata.ens-lyon.org ([127.0.0.1]) by localhost (sonata.ens-lyon.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id 9aK28YQjlEw2; Mon, 17 Apr 2023 00:07:04 +0200 (CEST) Received: from begin.home (apoitiers-658-1-118-253.w92-162.abo.wanadoo.fr [92.162.65.253]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange ECDHE (P-256) server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) by sonata.ens-lyon.org (Postfix) with ESMTPSA id BDA6220189; Mon, 17 Apr 2023 00:07:03 +0200 (CEST) Received: from samy by begin.home with local (Exim 4.96) (envelope-from ) id 1poAWW-003eXA-0I; Mon, 17 Apr 2023 00:07:04 +0200 Date: Mon, 17 Apr 2023 00:07:04 +0200 From: Samuel Thibault To: James Chapman , tparkin@katalix.com, edumazet@google.com Cc: davem@davemloft.net, kuba@kernel.org, pabeni@redhat.com, corbet@lwn.net, netdev@vger.kernel.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH] PPPoL2TP: Add more code snippets Message-ID: <20230416220704.xqk4q6uwjbujnqpv@begin> Mail-Followup-To: Samuel Thibault , James Chapman , tparkin@katalix.com, edumazet@google.com, davem@davemloft.net, kuba@kernel.org, pabeni@redhat.com, corbet@lwn.net, netdev@vger.kernel.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org MIME-Version: 1.0 Content-Disposition: inline User-Agent: NeoMutt/20170609 (1.8.3) X-Spam-Status: No, score=-1.9 required=5.0 tests=BAYES_00,RCVD_IN_DNSWL_NONE, SPF_HELO_PASS,SPF_PASS,T_SCC_BODY_TEXT_LINE autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org X-getmail-retrieved-from-mailbox: =?utf-8?q?INBOX?= X-GMAIL-THRID: =?utf-8?q?1763380903349162506?= X-GMAIL-MSGID: =?utf-8?q?1763382877551147313?= The existing documentation was not telling that one has to create a PPP channel and a PPP interface to get PPPoL2TP data offloading working. Also, tunnel switching was not described, so that people were thinking it was not supported, while it actually is. Signed-off-by: Samuel Thibault --- Documentation/networking/l2tp.rst | 59 ++++++++++++++++++++++++++++++++++++-- 1 file changed, 56 insertions(+), 3 deletions(-) --- a/Documentation/networking/l2tp.rst +++ b/Documentation/networking/l2tp.rst @@ -387,11 +387,12 @@ Sample userspace code: - Create session PPPoX data socket:: struct sockaddr_pppol2tp sax; - int fd; + int ret; /* Note, the tunnel socket must be bound already, else it * will not be ready */ + int session_fd = socket(AF_PPPOX, SOCK_DGRAM, PX_PROTO_OL2TP); sax.sa_family = AF_PPPOX; sax.sa_protocol = PX_PROTO_OL2TP; sax.pppol2tp.fd = tunnel_fd; @@ -406,12 +407,64 @@ Sample userspace code: /* session_fd is the fd of the session's PPPoL2TP socket. * tunnel_fd is the fd of the tunnel UDP / L2TPIP socket. */ - fd = connect(session_fd, (struct sockaddr *)&sax, sizeof(sax)); - if (fd < 0 ) { + ret = connect(session_fd, (struct sockaddr *)&sax, sizeof(sax)); + if (ret < 0 ) { return -errno; } return 0; + - Create PPP channel:: + + int chindx; + ret = ioctl(session_fd, PPPIOCGCHAN, &chindx); + if (ret < 0) + return -errno; + + int ppp_chan_fd = open("/dev/ppp", O_RDWR); + + ret = ioctl(ppp_chan_fd, PPPIOCATTCHAN, &chindx); + if (ret < 0) + return -errno; + +Non-data PPP frames will be available for read on `ppp_chan_fd`. + + - Create PPP interface:: + + int ppp_if_fd = open("/dev/ppp", O_RDWR); + + int ifunit; + ret = ioctl(ppp_if_fd, PPPIOCNEWUNIT, &ifunit); + if (ret < 0) + return -errno; + + ret = ioctl(ppp_chan_fd, PPPIOCCONNECT, ifunit); + if (ret < 0) + return -errno; + +The ppp interface can then be configured as usual with SIOCSIFMTU, +SIOCSIFADDR, SIOCSIFDSTADDR, SIOCSIFNETMASK, and activated by setting IFF_UP +with SIOCSIFFLAGS + + - Tunnel switching is supported by bridging channels:: + + int chindx; + ret = ioctl(session_fd, PPPIOCGCHAN, &chindx); + if (ret < 0) + return -errno; + + int chindx2; + ret = ioctl(session_fd2, PPPIOCGCHAN, &chind2x); + if (ret < 0) + return -errno; + + int ppp_chan_fd = open("/dev/ppp", O_RDWR); + + ret = ioctl(ppp_chan_fd, PPPIOCBRIDGECHAN, &chindx2); + if (ret < 0) + return -errno; + + close(ppp_chan_fd); + Old L2TPv2-only API -------------------