From mboxrd@z Thu Jan 1 00:00:00 1970 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=-16.6 required=3.0 tests=DKIMWL_WL_MED,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,USER_AGENT_GIT,USER_IN_DEF_DKIM_WL 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 D6D3BC169C4 for ; Tue, 12 Feb 2019 00:43:15 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 977C120844 for ; Tue, 12 Feb 2019 00:43:15 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="YODrrwje" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728058AbfBLAnO (ORCPT ); Mon, 11 Feb 2019 19:43:14 -0500 Received: from mail-it1-f202.google.com ([209.85.166.202]:59882 "EHLO mail-it1-f202.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727317AbfBLAnN (ORCPT ); Mon, 11 Feb 2019 19:43:13 -0500 Received: by mail-it1-f202.google.com with SMTP id m1so1490047ita.9 for ; Mon, 11 Feb 2019 16:43:12 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=date:in-reply-to:message-id:mime-version:references:subject:from:to :cc; bh=bTISPFnfIXlbp/7briABDSdYnlzXw750ojuoJyDfgyY=; b=YODrrwjexe6ZANyDrvne6SowEkAZjwvO6BL0ZFm1tBluuZv+G4/OXzx6Mo95C7kJKK e2FvAFMPB6zrjWgAv76WZiqX2Iw/kO0cpgQjMe0TvuSHZfgIlC5KPWqNVCE/NKHtlb5e H2cuLE/j0F3VgbWvGgY4M0h70hffkavJPq7SVbJQ6kEgPq2EZDM9PPRJETvk7A24Ri6y muKzznxrFbghm0XA2TdZ37qXHXEz1mBJH8TqQy04DGzz+wJj6Rpof+ezRtdtcjLMrLJe AY+KGF7pt8HjTW+mUtsUM6DSaf8GjtaX2VqQRqgY52cDZIYEeBq5fG3ftUx2rJNG9h5B c/Lg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:in-reply-to:message-id:mime-version :references:subject:from:to:cc; bh=bTISPFnfIXlbp/7briABDSdYnlzXw750ojuoJyDfgyY=; b=H4hK0+rADt1hViNUzTQrOE8KG8fw47fNmOwo9jqH2Ce/+rZEzkdZAVfSy+vDkmsm1c QB96I6gUIaGDlpq0ntLLpqM2UeqEm2PnjVUldX3ogIamJIEsJs9l5L2hAd0KTlLshwyG eCOHebSkZobAUGiQburGm2CF2oYUa0W1eQavZ4may837wLOlniD+uF1EWVRE8K81yQH6 hJiIwghDmV1V3nh1epTBKAuZrhnRUa9ULbAwfRPuna33vf7OZRK+c+Mg4XxaEQaVEOjX 63+T0eKOHFdCKu+6Igibx+nYcYIkTL+jbvM6sxp0pD1myqQ2R+pM16VPbJI7xgrZylfh XxiA== X-Gm-Message-State: AHQUAuaG/v0ryyZSLy59QtH18e2RY/gmA9v48ubOsrFEHiydi0+osxJG eKFqEEJVVLiPX9r7ABgp2nGvdEaj X-Google-Smtp-Source: AHgI3Iag9m01fLOr+oB7ic/BK7VwER+jAnlxsC4Rnd3PxKV6i4iZ6IBkoKiQcFRUhoxHMCSqHss1Fo0y X-Received: by 2002:a24:2f0e:: with SMTP id j14mr603542itj.14.1549932192052; Mon, 11 Feb 2019 16:43:12 -0800 (PST) Date: Mon, 11 Feb 2019 16:42:47 -0800 In-Reply-To: <20190212004249.219268-1-posk@google.com> Message-Id: <20190212004249.219268-6-posk@google.com> Mime-Version: 1.0 References: <20190212004249.219268-1-posk@google.com> X-Mailer: git-send-email 2.20.1.791.gb4d0f1c61a-goog Subject: [PATCH bpf-next v9 5/7] bpf: add handling of BPF_LWT_REROUTE to lwt_bpf.c From: Peter Oskolkov To: Alexei Starovoitov , Daniel Borkmann , netdev@vger.kernel.org Cc: Peter Oskolkov , David Ahern , Willem de Bruijn , Peter Oskolkov Content-Type: text/plain; charset="UTF-8" Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org This patch builds on top of the previous patch in the patchset, which added BPF_LWT_ENCAP_IP mode to bpf_lwt_push_encap. As the encapping can result in the skb needing to go via a different interface/route/dst, bpf programs can indicate this by returning BPF_LWT_REROUTE, which triggers a new route lookup for the skb. v8 changes: fix kbuild errors when LWTUNNEL_BPF is builtin, but IPV6 is a module: as LWTUNNEL_BPF can only be either Y or N, call IPV6 routing functions only if they are built-in. v9 changes: - fixed a kbuild test robot compiler warning; - call IPV6 routing functions via ipv6_stub. Signed-off-by: Peter Oskolkov --- net/core/lwt_bpf.c | 133 +++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 133 insertions(+) diff --git a/net/core/lwt_bpf.c b/net/core/lwt_bpf.c index 079871fc020f..aec5e6df880e 100644 --- a/net/core/lwt_bpf.c +++ b/net/core/lwt_bpf.c @@ -17,6 +17,7 @@ #include #include #include +#include struct bpf_lwt_prog { struct bpf_prog *prog; @@ -56,6 +57,7 @@ static int run_lwt_bpf(struct sk_buff *skb, struct bpf_lwt_prog *lwt, switch (ret) { case BPF_OK: + case BPF_LWT_REROUTE: break; case BPF_REDIRECT: @@ -88,6 +90,35 @@ static int run_lwt_bpf(struct sk_buff *skb, struct bpf_lwt_prog *lwt, return ret; } +static int bpf_lwt_input_reroute(struct sk_buff *skb) +{ + int err = -EINVAL; + + if (skb->protocol == htons(ETH_P_IP)) { + struct iphdr *iph = ip_hdr(skb); + + err = ip_route_input_noref(skb, iph->daddr, iph->saddr, + iph->tos, skb_dst(skb)->dev); + } else if (skb->protocol == htons(ETH_P_IPV6)) { +#if IS_ENABLED(CONFIG_IPV6) + err = ipv6_stub->ipv6_route_input(skb); +#else + pr_warn_once("BPF_LWT_REROUTE input: IPV6 not available\n"); +#endif + } else { + pr_warn_once("BPF_LWT_REROUTE input: unsupported proto %d\n", + skb->protocol); + } + + if (err) + goto err; + return dst_input(skb); + +err: + kfree_skb(skb); + return err; +} + static int bpf_input(struct sk_buff *skb) { struct dst_entry *dst = skb_dst(skb); @@ -99,6 +130,8 @@ static int bpf_input(struct sk_buff *skb) ret = run_lwt_bpf(skb, &bpf->in, dst, NO_REDIRECT); if (ret < 0) return ret; + if (ret == BPF_LWT_REROUTE) + return bpf_lwt_input_reroute(skb); } if (unlikely(!dst->lwtstate->orig_input)) { @@ -148,6 +181,95 @@ static int xmit_check_hhlen(struct sk_buff *skb) return 0; } +static int bpf_lwt_xmit_reroute(struct sk_buff *skb) +{ + struct net_device *l3mdev = l3mdev_master_dev_rcu(skb_dst(skb)->dev); + int oif = l3mdev ? l3mdev->ifindex : 0; + struct dst_entry *dst = NULL; + struct sock *sk; + struct net *net; + bool ipv4; + int err; + + if (skb->protocol == htons(ETH_P_IP)) { + ipv4 = true; + } else if (skb->protocol == htons(ETH_P_IPV6)) { + ipv4 = false; + } else { + pr_warn_once("BPF_LWT_REROUTE xmit: unsupported proto %d\n", + skb->protocol); + return -EINVAL; + } + + sk = sk_to_full_sk(skb->sk); + if (sk) { + if (sk->sk_bound_dev_if) + oif = sk->sk_bound_dev_if; + net = sock_net(sk); + } else { + net = dev_net(skb_dst(skb)->dev); + } + + if (ipv4) { + struct iphdr *iph = ip_hdr(skb); + struct flowi4 fl4 = {}; + struct rtable *rt; + + fl4.flowi4_oif = oif; + fl4.flowi4_mark = skb->mark; + fl4.flowi4_uid = sock_net_uid(net, sk); + fl4.flowi4_tos = RT_TOS(iph->tos); + fl4.flowi4_flags = FLOWI_FLAG_ANYSRC; + fl4.flowi4_proto = iph->protocol; + fl4.daddr = iph->daddr; + fl4.saddr = iph->saddr; + + rt = ip_route_output_key(net, &fl4); + if (IS_ERR(rt) || rt->dst.error) + return -EINVAL; + dst = &rt->dst; + } else { +#if IS_ENABLED(CONFIG_IPV6) + struct ipv6hdr *iph6 = ipv6_hdr(skb); + struct flowi6 fl6 = {}; + + fl6.flowi6_oif = oif; + fl6.flowi6_mark = skb->mark; + fl6.flowi6_uid = sock_net_uid(net, sk); + fl6.flowlabel = ip6_flowinfo(iph6); + fl6.flowi6_proto = iph6->nexthdr; + fl6.daddr = iph6->daddr; + fl6.saddr = iph6->saddr; + + err = ipv6_stub->ipv6_dst_lookup(net, skb->sk, &dst, &fl6); + if (err || IS_ERR(dst) || dst->error) + return -EINVAL; +#else + pr_warn_once("BPF_LWT_REROUTE xmit: IPV6 not available\n"); + return -EINVAL; +#endif + } + + /* Although skb header was reserved in bpf_lwt_push_ip_encap(), it + * was done for the previous dst, so we are doing it here again, in + * case the new dst needs much more space. The call below is a noop + * if there is enough header space in skb. + */ + err = skb_cow_head(skb, LL_RESERVED_SPACE(dst->dev)); + if (unlikely(err)) + return err; + + skb_dst_drop(skb); + skb_dst_set(skb, dst); + + err = dst_output(dev_net(skb_dst(skb)->dev), skb->sk, skb); + if (unlikely(err)) + return err; + + /* ip[6]_finish_output2 understand LWTUNNEL_XMIT_DONE */ + return LWTUNNEL_XMIT_DONE; +} + static int bpf_xmit(struct sk_buff *skb) { struct dst_entry *dst = skb_dst(skb); @@ -155,11 +277,20 @@ static int bpf_xmit(struct sk_buff *skb) bpf = bpf_lwt_lwtunnel(dst->lwtstate); if (bpf->xmit.prog) { + __be16 proto = skb->protocol; int ret; ret = run_lwt_bpf(skb, &bpf->xmit, dst, CAN_REDIRECT); switch (ret) { case BPF_OK: + /* If the header changed, e.g. via bpf_lwt_push_encap, + * BPF_LWT_REROUTE below should have been used if the + * protocol was also changed. + */ + if (skb->protocol != proto) { + kfree_skb(skb); + return -EINVAL; + } /* If the header was expanded, headroom might be too * small for L2 header to come, expand as needed. */ @@ -170,6 +301,8 @@ static int bpf_xmit(struct sk_buff *skb) return LWTUNNEL_XMIT_CONTINUE; case BPF_REDIRECT: return LWTUNNEL_XMIT_DONE; + case BPF_LWT_REROUTE: + return bpf_lwt_xmit_reroute(skb); default: return ret; } -- 2.20.1.791.gb4d0f1c61a-goog