From patchwork Thu Dec 17 17:26:20 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jesper Dangaard Brouer X-Patchwork-Id: 11980321 X-Patchwork-Delegate: bpf@iogearbox.net 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=-20.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING, SPF_HELO_NONE,SPF_PASS autolearn=unavailable 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 CAFD0C2BBCD for ; Thu, 17 Dec 2020 17:28:12 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A1B2223975 for ; Thu, 17 Dec 2020 17:28:12 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729641AbgLQR2A (ORCPT ); Thu, 17 Dec 2020 12:28:00 -0500 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:25579 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727368AbgLQR17 (ORCPT ); Thu, 17 Dec 2020 12:27:59 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1608225993; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=Z+tbcl4L04NWTojo+MJYMqV/uyN9LUn9rWpBUllzfzo=; b=Edg5LFJjipQoGIQQzUIOvFY4nDOsRAI6qVsC6Jjsf+wSl8wJJnaWW0kwxJMC13zK/FHaCS ObbDcw7m84zvVsafJhJ003437IBlXKrZN8dZXWJ35y5uyrNyAdZ11bUMp5azbS8rI3WNGR DabgFwdQ165353rX+W9Gz+E4FzSfvYA= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-449-ujgj3eiWM86cvQIjxi0HAg-1; Thu, 17 Dec 2020 12:26:28 -0500 X-MC-Unique: ujgj3eiWM86cvQIjxi0HAg-1 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 95665107ACFC; Thu, 17 Dec 2020 17:26:26 +0000 (UTC) Received: from firesoul.localdomain (unknown [10.40.208.19]) by smtp.corp.redhat.com (Postfix) with ESMTP id 771D760C15; Thu, 17 Dec 2020 17:26:21 +0000 (UTC) Received: from [192.168.42.3] (localhost [IPv6:::1]) by firesoul.localdomain (Postfix) with ESMTP id 7A32732138456; Thu, 17 Dec 2020 18:26:20 +0100 (CET) Subject: [PATCH bpf-next V9 1/7] bpf: Remove MTU check in __bpf_skb_max_len From: Jesper Dangaard Brouer To: bpf@vger.kernel.org Cc: Jesper Dangaard Brouer , netdev@vger.kernel.org, Daniel Borkmann , Alexei Starovoitov , maze@google.com, lmb@cloudflare.com, shaun@tigera.io, Lorenzo Bianconi , marek@cloudflare.com, John Fastabend , Jakub Kicinski , eyal.birger@gmail.com, colrack@gmail.com Date: Thu, 17 Dec 2020 18:26:20 +0100 Message-ID: <160822598043.3481451.9835885702372557530.stgit@firesoul> In-Reply-To: <160822594178.3481451.1208057539613401103.stgit@firesoul> References: <160822594178.3481451.1208057539613401103.stgit@firesoul> User-Agent: StGit/0.19 MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org X-Patchwork-Delegate: bpf@iogearbox.net Multiple BPF-helpers that can manipulate/increase the size of the SKB uses __bpf_skb_max_len() as the max-length. This function limit size against the current net_device MTU (skb->dev->mtu). When a BPF-prog grow the packet size, then it should not be limited to the MTU. The MTU is a transmit limitation, and software receiving this packet should be allowed to increase the size. Further more, current MTU check in __bpf_skb_max_len uses the MTU from ingress/current net_device, which in case of redirects uses the wrong net_device. This patch keeps a sanity max limit of SKB_MAX_ALLOC (16KiB). The real limit is elsewhere in the system. Jesper's testing[1] showed it was not possible to exceed 8KiB when expanding the SKB size via BPF-helper. The limiting factor is the define KMALLOC_MAX_CACHE_SIZE which is 8192 for SLUB-allocator (CONFIG_SLUB) in-case PAGE_SIZE is 4096. This define is in-effect due to this being called from softirq context see code __gfp_pfmemalloc_flags() and __do_kmalloc_node(). Jakub's testing showed that frames above 16KiB can cause NICs to reset (but not crash). Keep this sanity limit at this level as memory layer can differ based on kernel config. [1] https://github.com/xdp-project/bpf-examples/tree/master/MTU-tests V3: replace __bpf_skb_max_len() with define and use IPv6 max MTU size. Signed-off-by: Jesper Dangaard Brouer --- net/core/filter.c | 12 ++++-------- 1 file changed, 4 insertions(+), 8 deletions(-) diff --git a/net/core/filter.c b/net/core/filter.c index 255aeee72402..f8f198252ff2 100644 --- a/net/core/filter.c +++ b/net/core/filter.c @@ -3552,11 +3552,7 @@ static int bpf_skb_net_shrink(struct sk_buff *skb, u32 off, u32 len_diff, return 0; } -static u32 __bpf_skb_max_len(const struct sk_buff *skb) -{ - return skb->dev ? skb->dev->mtu + skb->dev->hard_header_len : - SKB_MAX_ALLOC; -} +#define BPF_SKB_MAX_LEN SKB_MAX_ALLOC BPF_CALL_4(sk_skb_adjust_room, struct sk_buff *, skb, s32, len_diff, u32, mode, u64, flags) @@ -3605,7 +3601,7 @@ BPF_CALL_4(bpf_skb_adjust_room, struct sk_buff *, skb, s32, len_diff, { u32 len_cur, len_diff_abs = abs(len_diff); u32 len_min = bpf_skb_net_base_len(skb); - u32 len_max = __bpf_skb_max_len(skb); + u32 len_max = BPF_SKB_MAX_LEN; __be16 proto = skb->protocol; bool shrink = len_diff < 0; u32 off; @@ -3688,7 +3684,7 @@ static int bpf_skb_trim_rcsum(struct sk_buff *skb, unsigned int new_len) static inline int __bpf_skb_change_tail(struct sk_buff *skb, u32 new_len, u64 flags) { - u32 max_len = __bpf_skb_max_len(skb); + u32 max_len = BPF_SKB_MAX_LEN; u32 min_len = __bpf_skb_min_len(skb); int ret; @@ -3764,7 +3760,7 @@ static const struct bpf_func_proto sk_skb_change_tail_proto = { static inline int __bpf_skb_change_head(struct sk_buff *skb, u32 head_room, u64 flags) { - u32 max_len = __bpf_skb_max_len(skb); + u32 max_len = BPF_SKB_MAX_LEN; u32 new_len = skb->len + head_room; int ret; From patchwork Thu Dec 17 17:26:25 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jesper Dangaard Brouer X-Patchwork-Id: 11980319 X-Patchwork-Delegate: bpf@iogearbox.net 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=-15.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 AF56AC2BBCF for ; 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Thu, 17 Dec 2020 12:26:33 -0500 X-MC-Unique: AcnmwB8oMfOHmN9ScNJWfA-1 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.phx2.redhat.com [10.5.11.16]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id EB3068030AD; Thu, 17 Dec 2020 17:26:31 +0000 (UTC) Received: from firesoul.localdomain (unknown [10.40.208.19]) by smtp.corp.redhat.com (Postfix) with ESMTP id 87A541B18A; Thu, 17 Dec 2020 17:26:26 +0000 (UTC) Received: from [192.168.42.3] (localhost [IPv6:::1]) by firesoul.localdomain (Postfix) with ESMTP id 8BD5D32138454; Thu, 17 Dec 2020 18:26:25 +0100 (CET) Subject: [PATCH bpf-next V9 2/7] bpf: fix bpf_fib_lookup helper MTU check for SKB ctx From: Jesper Dangaard Brouer To: bpf@vger.kernel.org Cc: Jesper Dangaard Brouer , netdev@vger.kernel.org, Daniel Borkmann , Alexei Starovoitov , maze@google.com, lmb@cloudflare.com, shaun@tigera.io, Lorenzo Bianconi , marek@cloudflare.com, John Fastabend , Jakub Kicinski , eyal.birger@gmail.com, colrack@gmail.com Date: Thu, 17 Dec 2020 18:26:25 +0100 Message-ID: <160822598551.3481451.14159825721005377499.stgit@firesoul> In-Reply-To: <160822594178.3481451.1208057539613401103.stgit@firesoul> References: <160822594178.3481451.1208057539613401103.stgit@firesoul> User-Agent: StGit/0.19 MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.16 Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org X-Patchwork-Delegate: bpf@iogearbox.net BPF end-user on Cilium slack-channel (Carlo Carraro) wants to use bpf_fib_lookup for doing MTU-check, but *prior* to extending packet size, by adjusting fib_params 'tot_len' with the packet length plus the expected encap size. (Just like the bpf_check_mtu helper supports). He discovered that for SKB ctx the param->tot_len was not used, instead skb->len was used (via MTU check in is_skb_forwardable()). Fix this by using fib_params 'tot_len' for MTU check. If not provided (e.g. zero) then keep existing behaviour intact. Fixes: 4c79579b44b1 ("bpf: Change bpf_fib_lookup to return lookup status") Reported-by: Carlo Carraro Signed-off-by: Jesper Dangaard Brouer --- net/core/filter.c | 14 ++++++++++++-- 1 file changed, 12 insertions(+), 2 deletions(-) diff --git a/net/core/filter.c b/net/core/filter.c index f8f198252ff2..95c6fdebd0db 100644 --- a/net/core/filter.c +++ b/net/core/filter.c @@ -5568,11 +5568,21 @@ BPF_CALL_4(bpf_skb_fib_lookup, struct sk_buff *, skb, #endif } - if (!rc) { + if (rc == BPF_FIB_LKUP_RET_SUCCESS) { struct net_device *dev; + u32 mtu; dev = dev_get_by_index_rcu(net, params->ifindex); - if (!is_skb_forwardable(dev, skb)) + mtu = READ_ONCE(dev->mtu); + + /* Using tot_len for (L3) MTU check if provided by user */ + if (params->tot_len && params->tot_len > mtu) + rc = BPF_FIB_LKUP_RET_FRAG_NEEDED; + + /* Notice at this TC cls_bpf level skb->len contains L2 size, + * but is_skb_forwardable takes that into account + */ + if (params->tot_len == 0 && !is_skb_forwardable(dev, skb)) rc = BPF_FIB_LKUP_RET_FRAG_NEEDED; } From patchwork Thu Dec 17 17:26:30 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jesper Dangaard Brouer X-Patchwork-Id: 11980323 X-Patchwork-Delegate: bpf@iogearbox.net 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=-15.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED 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 0B8EAC2D0E4 for ; Thu, 17 Dec 2020 17:28:13 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id E00F4238EF for ; Thu, 17 Dec 2020 17:28:12 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729744AbgLQR2H (ORCPT ); Thu, 17 Dec 2020 12:28:07 -0500 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:39426 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729742AbgLQR2G (ORCPT ); Thu, 17 Dec 2020 12:28:06 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1608225999; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=d/Cy4W//nHlsWEVXWh67UaS6yh9zDzqqgLnry7zT0Ko=; b=CMBl4lnvpHMbA3ku5zcxnCNqgOeCiAsdVQk2UhymqH6swcdiFAsuB1vHTJWmCbdSCiYxEH B+j6iTkqiwUmdTsB8dySIItoe38qFdclfrqLq0icE98006lmbhLSRN7GexzHjGrrl7zWYN 9LgfZ2P4IjM1LNcZT5DyW/Q2wKAl6T0= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-261-pckNb3VzMLe1HwsxFizECA-1; Thu, 17 Dec 2020 12:26:37 -0500 X-MC-Unique: pckNb3VzMLe1HwsxFizECA-1 Received: from smtp.corp.redhat.com (int-mx07.intmail.prod.int.phx2.redhat.com [10.5.11.22]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 6380E107ACFC; Thu, 17 Dec 2020 17:26:35 +0000 (UTC) Received: from firesoul.localdomain (unknown [10.40.208.19]) by smtp.corp.redhat.com (Postfix) with ESMTP id A1EDF100238C; Thu, 17 Dec 2020 17:26:31 +0000 (UTC) Received: from [192.168.42.3] (localhost [IPv6:::1]) by firesoul.localdomain (Postfix) with ESMTP id A03BD32138456; Thu, 17 Dec 2020 18:26:30 +0100 (CET) Subject: [PATCH bpf-next V9 3/7] bpf: bpf_fib_lookup return MTU value as output when looked up From: Jesper Dangaard Brouer To: bpf@vger.kernel.org Cc: Jesper Dangaard Brouer , netdev@vger.kernel.org, Daniel Borkmann , Alexei Starovoitov , maze@google.com, lmb@cloudflare.com, shaun@tigera.io, Lorenzo Bianconi , marek@cloudflare.com, John Fastabend , Jakub Kicinski , eyal.birger@gmail.com, colrack@gmail.com Date: Thu, 17 Dec 2020 18:26:30 +0100 Message-ID: <160822599058.3481451.14379555697407003614.stgit@firesoul> In-Reply-To: <160822594178.3481451.1208057539613401103.stgit@firesoul> References: <160822594178.3481451.1208057539613401103.stgit@firesoul> User-Agent: StGit/0.19 MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.84 on 10.5.11.22 Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org X-Patchwork-Delegate: bpf@iogearbox.net The BPF-helpers for FIB lookup (bpf_xdp_fib_lookup and bpf_skb_fib_lookup) can perform MTU check and return BPF_FIB_LKUP_RET_FRAG_NEEDED. The BPF-prog don't know the MTU value that caused this rejection. If the BPF-prog wants to implement PMTU (Path MTU Discovery) (rfc1191) it need to know this MTU value for the ICMP packet. Patch change lookup and result struct bpf_fib_lookup, to contain this MTU value as output via a union with 'tot_len' as this is the value used for the MTU lookup. V5: - Fixed uninit value spotted by Dan Carpenter. - Name struct output member mtu_result Reported-by: kernel test robot Reported-by: Dan Carpenter Signed-off-by: Jesper Dangaard Brouer --- include/uapi/linux/bpf.h | 11 +++++++++-- net/core/filter.c | 22 +++++++++++++++------- tools/include/uapi/linux/bpf.h | 11 +++++++++-- 3 files changed, 33 insertions(+), 11 deletions(-) diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h index 77d7c1bb2923..649586d656b6 100644 --- a/include/uapi/linux/bpf.h +++ b/include/uapi/linux/bpf.h @@ -2225,6 +2225,9 @@ union bpf_attr { * * > 0 one of **BPF_FIB_LKUP_RET_** codes explaining why the * packet is not forwarded or needs assist from full stack * + * If lookup fails with BPF_FIB_LKUP_RET_FRAG_NEEDED, then the MTU + * was exceeded and output params->mtu_result contains the MTU. + * * long bpf_sock_hash_update(struct bpf_sock_ops *skops, struct bpf_map *map, void *key, u64 flags) * Description * Add an entry to, or update a sockhash *map* referencing sockets. @@ -4975,9 +4978,13 @@ struct bpf_fib_lookup { __be16 sport; __be16 dport; - /* total length of packet from network header - used for MTU check */ - __u16 tot_len; + union { /* used for MTU check */ + /* input to lookup */ + __u16 tot_len; /* L3 length from network hdr (iph->tot_len) */ + /* output: MTU value */ + __u16 mtu_result; + }; /* input: L3 device index for lookup * output: device index from FIB lookup */ diff --git a/net/core/filter.c b/net/core/filter.c index 95c6fdebd0db..722910cbfe0b 100644 --- a/net/core/filter.c +++ b/net/core/filter.c @@ -5268,12 +5268,14 @@ static const struct bpf_func_proto bpf_skb_get_xfrm_state_proto = { #if IS_ENABLED(CONFIG_INET) || IS_ENABLED(CONFIG_IPV6) static int bpf_fib_set_fwd_params(struct bpf_fib_lookup *params, const struct neighbour *neigh, - const struct net_device *dev) + const struct net_device *dev, u32 mtu) { memcpy(params->dmac, neigh->ha, ETH_ALEN); memcpy(params->smac, dev->dev_addr, ETH_ALEN); params->h_vlan_TCI = 0; params->h_vlan_proto = 0; + if (mtu) + params->mtu_result = mtu; /* union with tot_len */ return 0; } @@ -5289,8 +5291,8 @@ static int bpf_ipv4_fib_lookup(struct net *net, struct bpf_fib_lookup *params, struct net_device *dev; struct fib_result res; struct flowi4 fl4; + u32 mtu = 0; int err; - u32 mtu; dev = dev_get_by_index_rcu(net, params->ifindex); if (unlikely(!dev)) @@ -5357,8 +5359,10 @@ static int bpf_ipv4_fib_lookup(struct net *net, struct bpf_fib_lookup *params, if (check_mtu) { mtu = ip_mtu_from_fib_result(&res, params->ipv4_dst); - if (params->tot_len > mtu) + if (params->tot_len > mtu) { + params->mtu_result = mtu; /* union with tot_len */ return BPF_FIB_LKUP_RET_FRAG_NEEDED; + } } nhc = res.nhc; @@ -5392,7 +5396,7 @@ static int bpf_ipv4_fib_lookup(struct net *net, struct bpf_fib_lookup *params, if (!neigh) return BPF_FIB_LKUP_RET_NO_NEIGH; - return bpf_fib_set_fwd_params(params, neigh, dev); + return bpf_fib_set_fwd_params(params, neigh, dev, mtu); } #endif @@ -5409,7 +5413,7 @@ static int bpf_ipv6_fib_lookup(struct net *net, struct bpf_fib_lookup *params, struct flowi6 fl6; int strict = 0; int oif, err; - u32 mtu; + u32 mtu = 0; /* link local addresses are never forwarded */ if (rt6_need_strict(dst) || rt6_need_strict(src)) @@ -5484,8 +5488,10 @@ static int bpf_ipv6_fib_lookup(struct net *net, struct bpf_fib_lookup *params, if (check_mtu) { mtu = ipv6_stub->ip6_mtu_from_fib6(&res, dst, src); - if (params->tot_len > mtu) + if (params->tot_len > mtu) { + params->mtu_result = mtu; /* union with tot_len */ return BPF_FIB_LKUP_RET_FRAG_NEEDED; + } } if (res.nh->fib_nh_lws) @@ -5505,7 +5511,7 @@ static int bpf_ipv6_fib_lookup(struct net *net, struct bpf_fib_lookup *params, if (!neigh) return BPF_FIB_LKUP_RET_NO_NEIGH; - return bpf_fib_set_fwd_params(params, neigh, dev); + return bpf_fib_set_fwd_params(params, neigh, dev, mtu); } #endif @@ -5584,6 +5590,8 @@ BPF_CALL_4(bpf_skb_fib_lookup, struct sk_buff *, skb, */ if (params->tot_len == 0 && !is_skb_forwardable(dev, skb)) rc = BPF_FIB_LKUP_RET_FRAG_NEEDED; + + params->mtu_result = dev->mtu; /* union with tot_len */ } return rc; diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h index 77d7c1bb2923..649586d656b6 100644 --- a/tools/include/uapi/linux/bpf.h +++ b/tools/include/uapi/linux/bpf.h @@ -2225,6 +2225,9 @@ union bpf_attr { * * > 0 one of **BPF_FIB_LKUP_RET_** codes explaining why the * packet is not forwarded or needs assist from full stack * + * If lookup fails with BPF_FIB_LKUP_RET_FRAG_NEEDED, then the MTU + * was exceeded and output params->mtu_result contains the MTU. + * * long bpf_sock_hash_update(struct bpf_sock_ops *skops, struct bpf_map *map, void *key, u64 flags) * Description * Add an entry to, or update a sockhash *map* referencing sockets. @@ -4975,9 +4978,13 @@ struct bpf_fib_lookup { __be16 sport; __be16 dport; - /* total length of packet from network header - used for MTU check */ - __u16 tot_len; + union { /* used for MTU check */ + /* input to lookup */ + __u16 tot_len; /* L3 length from network hdr (iph->tot_len) */ + /* output: MTU value */ + __u16 mtu_result; + }; /* input: L3 device index for lookup * output: device index from FIB lookup */ From patchwork Thu Dec 17 17:26:35 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jesper Dangaard Brouer X-Patchwork-Id: 11980325 X-Patchwork-Delegate: bpf@iogearbox.net 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=-15.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=unavailable 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 DE332C2BB9A for ; Thu, 17 Dec 2020 17:28:47 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B89BB238EF for ; 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Thu, 17 Dec 2020 12:26:40 -0500 X-MC-Unique: Uz5Zli2wOB27wZN0D1jGAg-1 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 82542873165; Thu, 17 Dec 2020 17:26:37 +0000 (UTC) Received: from firesoul.localdomain (unknown [10.40.208.19]) by smtp.corp.redhat.com (Postfix) with ESMTP id CCAAB60BE5; Thu, 17 Dec 2020 17:26:36 +0000 (UTC) Received: from [192.168.42.3] (localhost [IPv6:::1]) by firesoul.localdomain (Postfix) with ESMTP id BC70F32138454; Thu, 17 Dec 2020 18:26:35 +0100 (CET) Subject: [PATCH bpf-next V9 4/7] bpf: add BPF-helper for MTU checking From: Jesper Dangaard Brouer To: bpf@vger.kernel.org Cc: Jesper Dangaard Brouer , netdev@vger.kernel.org, Daniel Borkmann , Alexei Starovoitov , maze@google.com, lmb@cloudflare.com, shaun@tigera.io, Lorenzo Bianconi , marek@cloudflare.com, John Fastabend , Jakub Kicinski , eyal.birger@gmail.com, colrack@gmail.com Date: Thu, 17 Dec 2020 18:26:35 +0100 Message-ID: <160822599569.3481451.18036590418835988911.stgit@firesoul> In-Reply-To: <160822594178.3481451.1208057539613401103.stgit@firesoul> References: <160822594178.3481451.1208057539613401103.stgit@firesoul> User-Agent: StGit/0.19 MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org X-Patchwork-Delegate: bpf@iogearbox.net This BPF-helper bpf_check_mtu() works for both XDP and TC-BPF programs. The SKB object is complex and the skb->len value (accessible from BPF-prog) also include the length of any extra GRO/GSO segments, but without taking into account that these GRO/GSO segments get added transport (L4) and network (L3) headers before being transmitted. Thus, this BPF-helper is created such that the BPF-programmer don't need to handle these details in the BPF-prog. The API is designed to help the BPF-programmer, that want to do packet context size changes, which involves other helpers. These other helpers usually does a delta size adjustment. This helper also support a delta size (len_diff), which allow BPF-programmer to reuse arguments needed by these other helpers, and perform the MTU check prior to doing any actual size adjustment of the packet context. It is on purpose, that we allow the len adjustment to become a negative result, that will pass the MTU check. This might seem weird, but it's not this helpers responsibility to "catch" wrong len_diff adjustments. Other helpers will take care of these checks, if BPF-programmer chooses to do actual size adjustment. V9: - Use dev->hard_header_len (instead of ETH_HLEN) - Annotate with unlikely req from Daniel - Fix logic error using skb_gso_validate_network_len from Daniel V6: - Took John's advice and dropped BPF_MTU_CHK_RELAX - Returned MTU is kept at L3-level (like fib_lookup) V4: Lot of changes - ifindex 0 now use current netdev for MTU lookup - rename helper from bpf_mtu_check to bpf_check_mtu - fix bug for GSO pkt length (as skb->len is total len) - remove __bpf_len_adj_positive, simply allow negative len adj Signed-off-by: Jesper Dangaard Brouer --- include/uapi/linux/bpf.h | 67 ++++++++++++++++++++++ net/core/filter.c | 122 ++++++++++++++++++++++++++++++++++++++++ tools/include/uapi/linux/bpf.h | 67 ++++++++++++++++++++++ 3 files changed, 256 insertions(+) diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h index 649586d656b6..fa2e99351758 100644 --- a/include/uapi/linux/bpf.h +++ b/include/uapi/linux/bpf.h @@ -3833,6 +3833,61 @@ union bpf_attr { * Return * A pointer to a struct socket on success or NULL if the file is * not a socket. + * + * int bpf_check_mtu(void *ctx, u32 ifindex, u32 *mtu_len, s32 len_diff, u64 flags) + * Description + * Check ctx packet size against MTU of net device (based on + * *ifindex*). This helper will likely be used in combination with + * helpers that adjust/change the packet size. The argument + * *len_diff* can be used for querying with a planned size + * change. This allows to check MTU prior to changing packet ctx. + * + * Specifying *ifindex* zero means the MTU check is performed + * against the current net device. This is practical if this isn't + * used prior to redirect. + * + * The Linux kernel route table can configure MTUs on a more + * specific per route level, which is not provided by this helper. + * For route level MTU checks use the **bpf_fib_lookup**\ () + * helper. + * + * *ctx* is either **struct xdp_md** for XDP programs or + * **struct sk_buff** for tc cls_act programs. + * + * The *flags* argument can be a combination of one or more of the + * following values: + * + * **BPF_MTU_CHK_SEGS** + * This flag will only works for *ctx* **struct sk_buff**. + * If packet context contains extra packet segment buffers + * (often knows as GSO skb), then MTU check is harder to + * check at this point, because in transmit path it is + * possible for the skb packet to get re-segmented + * (depending on net device features). This could still be + * a MTU violation, so this flag enables performing MTU + * check against segments, with a different violation + * return code to tell it apart. Check cannot use len_diff. + * + * On return *mtu_len* pointer contains the MTU value of the net + * device. Remember the net device configured MTU is the L3 size, + * which is returned here and XDP and TX length operate at L2. + * Helper take this into account for you, but remember when using + * MTU value in your BPF-code. On input *mtu_len* must be a valid + * pointer and be initialized (to zero), else verifier will reject + * BPF program. + * + * Return + * * 0 on success, and populate MTU value in *mtu_len* pointer. + * + * * < 0 if any input argument is invalid (*mtu_len* not updated) + * + * MTU violations return positive values, but also populate MTU + * value in *mtu_len* pointer, as this can be needed for + * implementing PMTU handing: + * + * * **BPF_MTU_CHK_RET_FRAG_NEEDED** + * * **BPF_MTU_CHK_RET_SEGS_TOOBIG** + * */ #define __BPF_FUNC_MAPPER(FN) \ FN(unspec), \ @@ -3998,6 +4053,7 @@ union bpf_attr { FN(ktime_get_coarse_ns), \ FN(ima_inode_hash), \ FN(sock_from_file), \ + FN(check_mtu), \ /* */ /* integer value in 'imm' field of BPF_CALL instruction selects which helper @@ -5030,6 +5086,17 @@ struct bpf_redir_neigh { }; }; +/* bpf_check_mtu flags*/ +enum bpf_check_mtu_flags { + BPF_MTU_CHK_SEGS = (1U << 0), +}; + +enum bpf_check_mtu_ret { + BPF_MTU_CHK_RET_SUCCESS, /* check and lookup successful */ + BPF_MTU_CHK_RET_FRAG_NEEDED, /* fragmentation required to fwd */ + BPF_MTU_CHK_RET_SEGS_TOOBIG, /* GSO re-segmentation needed to fwd */ +}; + enum bpf_task_fd_type { BPF_FD_TYPE_RAW_TRACEPOINT, /* tp name */ BPF_FD_TYPE_TRACEPOINT, /* tp name */ diff --git a/net/core/filter.c b/net/core/filter.c index 722910cbfe0b..6e113de2baae 100644 --- a/net/core/filter.c +++ b/net/core/filter.c @@ -5607,6 +5607,124 @@ static const struct bpf_func_proto bpf_skb_fib_lookup_proto = { .arg4_type = ARG_ANYTHING, }; +static struct net_device *__dev_via_ifindex(struct net_device *dev_curr, + u32 ifindex) +{ + struct net *netns = dev_net(dev_curr); + + /* Non-redirect use-cases can use ifindex=0 and save ifindex lookup */ + if (ifindex == 0) + return dev_curr; + + return dev_get_by_index_rcu(netns, ifindex); +} + +BPF_CALL_5(bpf_skb_check_mtu, struct sk_buff *, skb, + u32, ifindex, u32 *, mtu_len, s32, len_diff, u64, flags) +{ + int ret = BPF_MTU_CHK_RET_FRAG_NEEDED; + struct net_device *dev = skb->dev; + int skb_len, dev_len; + int mtu; + + if (unlikely(flags & ~(BPF_MTU_CHK_SEGS))) + return -EINVAL; + + dev = __dev_via_ifindex(dev, ifindex); + if (unlikely(!dev)) + return -ENODEV; + + mtu = READ_ONCE(dev->mtu); + + dev_len = mtu + dev->hard_header_len; + skb_len = skb->len + len_diff; /* minus result pass check */ + if (skb_len <= dev_len) { + ret = BPF_MTU_CHK_RET_SUCCESS; + goto out; + } + /* At this point, skb->len exceed MTU, but as it include length of all + * segments, it can still be below MTU. The SKB can possibly get + * re-segmented in transmit path (see validate_xmit_skb). Thus, user + * must choose if segs are to be MTU checked. Last SKB "headlen" is + * checked against MTU. + */ + if (skb_is_gso(skb)) { + ret = BPF_MTU_CHK_RET_SUCCESS; + + if (!(flags & BPF_MTU_CHK_SEGS)) + goto out; + + if (!skb_gso_validate_network_len(skb, mtu)) { + ret = BPF_MTU_CHK_RET_SEGS_TOOBIG; + goto out; + } + + skb_len = skb_headlen(skb) + len_diff; + if (skb_len > dev_len) { + ret = BPF_MTU_CHK_RET_FRAG_NEEDED; + goto out; + } + } +out: + /* BPF verifier guarantees valid pointer */ + *mtu_len = mtu; + + return ret; +} + +BPF_CALL_5(bpf_xdp_check_mtu, struct xdp_buff *, xdp, + u32, ifindex, u32 *, mtu_len, s32, len_diff, u64, flags) +{ + struct net_device *dev = xdp->rxq->dev; + int xdp_len = xdp->data_end - xdp->data; + int ret = BPF_MTU_CHK_RET_SUCCESS; + int mtu, dev_len; + + /* XDP variant doesn't support multi-buffer segment check (yet) */ + if (unlikely(flags)) + return -EINVAL; + + dev = __dev_via_ifindex(dev, ifindex); + if (unlikely(!dev)) + return -ENODEV; + + mtu = READ_ONCE(dev->mtu); + + /* Add L2-header as dev MTU is L3 size */ + dev_len = mtu + dev->hard_header_len; + + xdp_len += len_diff; /* minus result pass check */ + if (xdp_len > dev_len) + ret = BPF_MTU_CHK_RET_FRAG_NEEDED; + + /* BPF verifier guarantees valid pointer */ + *mtu_len = mtu; + + return ret; +} + +static const struct bpf_func_proto bpf_skb_check_mtu_proto = { + .func = bpf_skb_check_mtu, + .gpl_only = true, + .ret_type = RET_INTEGER, + .arg1_type = ARG_PTR_TO_CTX, + .arg2_type = ARG_ANYTHING, + .arg3_type = ARG_PTR_TO_INT, + .arg4_type = ARG_ANYTHING, + .arg5_type = ARG_ANYTHING, +}; + +static const struct bpf_func_proto bpf_xdp_check_mtu_proto = { + .func = bpf_xdp_check_mtu, + .gpl_only = true, + .ret_type = RET_INTEGER, + .arg1_type = ARG_PTR_TO_CTX, + .arg2_type = ARG_ANYTHING, + .arg3_type = ARG_PTR_TO_INT, + .arg4_type = ARG_ANYTHING, + .arg5_type = ARG_ANYTHING, +}; + #if IS_ENABLED(CONFIG_IPV6_SEG6_BPF) static int bpf_push_seg6_encap(struct sk_buff *skb, u32 type, void *hdr, u32 len) { @@ -7176,6 +7294,8 @@ tc_cls_act_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog) return &bpf_get_socket_uid_proto; case BPF_FUNC_fib_lookup: return &bpf_skb_fib_lookup_proto; + case BPF_FUNC_check_mtu: + return &bpf_skb_check_mtu_proto; case BPF_FUNC_sk_fullsock: return &bpf_sk_fullsock_proto; case BPF_FUNC_sk_storage_get: @@ -7245,6 +7365,8 @@ xdp_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog) return &bpf_xdp_adjust_tail_proto; case BPF_FUNC_fib_lookup: return &bpf_xdp_fib_lookup_proto; + case BPF_FUNC_check_mtu: + return &bpf_xdp_check_mtu_proto; #ifdef CONFIG_INET case BPF_FUNC_sk_lookup_udp: return &bpf_xdp_sk_lookup_udp_proto; diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h index 649586d656b6..fa2e99351758 100644 --- a/tools/include/uapi/linux/bpf.h +++ b/tools/include/uapi/linux/bpf.h @@ -3833,6 +3833,61 @@ union bpf_attr { * Return * A pointer to a struct socket on success or NULL if the file is * not a socket. + * + * int bpf_check_mtu(void *ctx, u32 ifindex, u32 *mtu_len, s32 len_diff, u64 flags) + * Description + * Check ctx packet size against MTU of net device (based on + * *ifindex*). This helper will likely be used in combination with + * helpers that adjust/change the packet size. The argument + * *len_diff* can be used for querying with a planned size + * change. This allows to check MTU prior to changing packet ctx. + * + * Specifying *ifindex* zero means the MTU check is performed + * against the current net device. This is practical if this isn't + * used prior to redirect. + * + * The Linux kernel route table can configure MTUs on a more + * specific per route level, which is not provided by this helper. + * For route level MTU checks use the **bpf_fib_lookup**\ () + * helper. + * + * *ctx* is either **struct xdp_md** for XDP programs or + * **struct sk_buff** for tc cls_act programs. + * + * The *flags* argument can be a combination of one or more of the + * following values: + * + * **BPF_MTU_CHK_SEGS** + * This flag will only works for *ctx* **struct sk_buff**. + * If packet context contains extra packet segment buffers + * (often knows as GSO skb), then MTU check is harder to + * check at this point, because in transmit path it is + * possible for the skb packet to get re-segmented + * (depending on net device features). This could still be + * a MTU violation, so this flag enables performing MTU + * check against segments, with a different violation + * return code to tell it apart. Check cannot use len_diff. + * + * On return *mtu_len* pointer contains the MTU value of the net + * device. Remember the net device configured MTU is the L3 size, + * which is returned here and XDP and TX length operate at L2. + * Helper take this into account for you, but remember when using + * MTU value in your BPF-code. On input *mtu_len* must be a valid + * pointer and be initialized (to zero), else verifier will reject + * BPF program. + * + * Return + * * 0 on success, and populate MTU value in *mtu_len* pointer. + * + * * < 0 if any input argument is invalid (*mtu_len* not updated) + * + * MTU violations return positive values, but also populate MTU + * value in *mtu_len* pointer, as this can be needed for + * implementing PMTU handing: + * + * * **BPF_MTU_CHK_RET_FRAG_NEEDED** + * * **BPF_MTU_CHK_RET_SEGS_TOOBIG** + * */ #define __BPF_FUNC_MAPPER(FN) \ FN(unspec), \ @@ -3998,6 +4053,7 @@ union bpf_attr { FN(ktime_get_coarse_ns), \ FN(ima_inode_hash), \ FN(sock_from_file), \ + FN(check_mtu), \ /* */ /* integer value in 'imm' field of BPF_CALL instruction selects which helper @@ -5030,6 +5086,17 @@ struct bpf_redir_neigh { }; }; +/* bpf_check_mtu flags*/ +enum bpf_check_mtu_flags { + BPF_MTU_CHK_SEGS = (1U << 0), +}; + +enum bpf_check_mtu_ret { + BPF_MTU_CHK_RET_SUCCESS, /* check and lookup successful */ + BPF_MTU_CHK_RET_FRAG_NEEDED, /* fragmentation required to fwd */ + BPF_MTU_CHK_RET_SEGS_TOOBIG, /* GSO re-segmentation needed to fwd */ +}; + enum bpf_task_fd_type { BPF_FD_TYPE_RAW_TRACEPOINT, /* tp name */ BPF_FD_TYPE_TRACEPOINT, /* tp name */ From patchwork Thu Dec 17 17:26:40 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jesper Dangaard Brouer X-Patchwork-Id: 11980327 X-Patchwork-Delegate: bpf@iogearbox.net 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=-15.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=unavailable 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 F21A8C2BB48 for ; Thu, 17 Dec 2020 17:28:47 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id CCE012395A for ; Thu, 17 Dec 2020 17:28:47 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729183AbgLQR2U (ORCPT ); Thu, 17 Dec 2020 12:28:20 -0500 Received: from us-smtp-delivery-124.mimecast.com ([63.128.21.124]:43255 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728081AbgLQR2U (ORCPT ); Thu, 17 Dec 2020 12:28:20 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1608226013; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=0Cv65WGv5GA8C06IHGJh91pTKR9Na0UhtVnmhg+i5qs=; b=DPsv0hKQs+xlErgXKL8wrq2owD1c1x9qlhZmppvKQCZ48Se20NQ7H2bF5cvalgHd+1sTdx ckQ0EspfB+ChsFKVNfp8uW8KjzKe6d6qUS2z+I2/KDlmrqYk68F57iSF9b76I3UYe/5cU0 MeH87Voe+dGFsoSxE7UspS3fpLfnQRk= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-426-U56zSEDWONm7Iw9u0vAZVQ-1; Thu, 17 Dec 2020 12:26:48 -0500 X-MC-Unique: U56zSEDWONm7Iw9u0vAZVQ-1 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id E54306D54D; Thu, 17 Dec 2020 17:26:45 +0000 (UTC) Received: from firesoul.localdomain (unknown [10.40.208.19]) by smtp.corp.redhat.com (Postfix) with ESMTP id CC52A18993; Thu, 17 Dec 2020 17:26:41 +0000 (UTC) Received: from [192.168.42.3] (localhost [IPv6:::1]) by firesoul.localdomain (Postfix) with ESMTP id D03BC32138454; Thu, 17 Dec 2020 18:26:40 +0100 (CET) Subject: [PATCH bpf-next V9 5/7] bpf: drop MTU check when doing TC-BPF redirect to ingress From: Jesper Dangaard Brouer To: bpf@vger.kernel.org Cc: Jesper Dangaard Brouer , netdev@vger.kernel.org, Daniel Borkmann , Alexei Starovoitov , maze@google.com, lmb@cloudflare.com, shaun@tigera.io, Lorenzo Bianconi , marek@cloudflare.com, John Fastabend , Jakub Kicinski , eyal.birger@gmail.com, colrack@gmail.com Date: Thu, 17 Dec 2020 18:26:40 +0100 Message-ID: <160822600078.3481451.1710106249316458942.stgit@firesoul> In-Reply-To: <160822594178.3481451.1208057539613401103.stgit@firesoul> References: <160822594178.3481451.1208057539613401103.stgit@firesoul> User-Agent: StGit/0.19 MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org X-Patchwork-Delegate: bpf@iogearbox.net The use-case for dropping the MTU check when TC-BPF does redirect to ingress, is described by Eyal Birger in email[0]. The summary is the ability to increase packet size (e.g. with IPv6 headers for NAT64) and ingress redirect packet and let normal netstack fragment packet as needed. [0] https://lore.kernel.org/netdev/CAHsH6Gug-hsLGHQ6N0wtixdOa85LDZ3HNRHVd0opR=19Qo4W4Q@mail.gmail.com/ V9: - Make net_device "up" (IFF_UP) check explicit in skb_do_redirect V4: - Keep net_device "up" (IFF_UP) check. - Adjustment to handle bpf_redirect_peer() helper Signed-off-by: Jesper Dangaard Brouer --- include/linux/netdevice.h | 31 +++++++++++++++++++++++++++++-- net/core/dev.c | 19 ++----------------- net/core/filter.c | 14 +++++++++++--- 3 files changed, 42 insertions(+), 22 deletions(-) diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h index 7bf167993c05..4c78f73db1ec 100644 --- a/include/linux/netdevice.h +++ b/include/linux/netdevice.h @@ -3947,11 +3947,38 @@ int dev_forward_skb(struct net_device *dev, struct sk_buff *skb); bool is_skb_forwardable(const struct net_device *dev, const struct sk_buff *skb); +static __always_inline bool __is_skb_forwardable(const struct net_device *dev, + const struct sk_buff *skb, + const bool check_mtu) +{ + const u32 vlan_hdr_len = 4; /* VLAN_HLEN */ + unsigned int len; + + if (!(dev->flags & IFF_UP)) + return false; + + if (!check_mtu) + return true; + + len = dev->mtu + dev->hard_header_len + vlan_hdr_len; + if (skb->len <= len) + return true; + + /* if TSO is enabled, we don't care about the length as the packet + * could be forwarded without being segmented before + */ + if (skb_is_gso(skb)) + return true; + + return false; +} + static __always_inline int ____dev_forward_skb(struct net_device *dev, - struct sk_buff *skb) + struct sk_buff *skb, + const bool check_mtu) { if (skb_orphan_frags(skb, GFP_ATOMIC) || - unlikely(!is_skb_forwardable(dev, skb))) { + unlikely(!__is_skb_forwardable(dev, skb, check_mtu))) { atomic_long_inc(&dev->rx_dropped); kfree_skb(skb); return NET_RX_DROP; diff --git a/net/core/dev.c b/net/core/dev.c index a46334906c94..ffead13c158f 100644 --- a/net/core/dev.c +++ b/net/core/dev.c @@ -2176,28 +2176,13 @@ static inline void net_timestamp_set(struct sk_buff *skb) bool is_skb_forwardable(const struct net_device *dev, const struct sk_buff *skb) { - unsigned int len; - - if (!(dev->flags & IFF_UP)) - return false; - - len = dev->mtu + dev->hard_header_len + VLAN_HLEN; - if (skb->len <= len) - return true; - - /* if TSO is enabled, we don't care about the length as the packet - * could be forwarded without being segmented before - */ - if (skb_is_gso(skb)) - return true; - - return false; + return __is_skb_forwardable(dev, skb, true); } EXPORT_SYMBOL_GPL(is_skb_forwardable); int __dev_forward_skb(struct net_device *dev, struct sk_buff *skb) { - int ret = ____dev_forward_skb(dev, skb); + int ret = ____dev_forward_skb(dev, skb, true); if (likely(!ret)) { skb->protocol = eth_type_trans(skb, dev); diff --git a/net/core/filter.c b/net/core/filter.c index 6e113de2baae..b682b11fbbec 100644 --- a/net/core/filter.c +++ b/net/core/filter.c @@ -2083,13 +2083,21 @@ static const struct bpf_func_proto bpf_csum_level_proto = { static inline int __bpf_rx_skb(struct net_device *dev, struct sk_buff *skb) { - return dev_forward_skb(dev, skb); + int ret = ____dev_forward_skb(dev, skb, false); + + if (likely(!ret)) { + skb->protocol = eth_type_trans(skb, dev); + skb_postpull_rcsum(skb, eth_hdr(skb), ETH_HLEN); + ret = netif_rx(skb); + } + + return ret; } static inline int __bpf_rx_skb_no_mac(struct net_device *dev, struct sk_buff *skb) { - int ret = ____dev_forward_skb(dev, skb); + int ret = ____dev_forward_skb(dev, skb, false); if (likely(!ret)) { skb->dev = dev; @@ -2480,7 +2488,7 @@ int skb_do_redirect(struct sk_buff *skb) goto out_drop; dev = ops->ndo_get_peer_dev(dev); if (unlikely(!dev || - !is_skb_forwardable(dev, skb) || + !(dev->flags & IFF_UP) || net_eq(net, dev_net(dev)))) goto out_drop; skb->dev = dev; From patchwork Thu Dec 17 17:26:45 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jesper Dangaard Brouer X-Patchwork-Id: 11980329 X-Patchwork-Delegate: bpf@iogearbox.net 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=-15.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=unavailable 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 39B14C2BBCD for ; 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Thu, 17 Dec 2020 12:26:50 -0500 X-MC-Unique: 0Am4hGVaMgCz-dI155VMvA-1 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 3EFD1107ACE8; Thu, 17 Dec 2020 17:26:47 +0000 (UTC) Received: from firesoul.localdomain (unknown [10.40.208.19]) by smtp.corp.redhat.com (Postfix) with ESMTP id ECA1518993; Thu, 17 Dec 2020 17:26:46 +0000 (UTC) Received: from [192.168.42.3] (localhost [IPv6:::1]) by firesoul.localdomain (Postfix) with ESMTP id E13B132138456; Thu, 17 Dec 2020 18:26:45 +0100 (CET) Subject: [PATCH bpf-next V9 6/7] selftests/bpf: use bpf_check_mtu in selftest test_cls_redirect From: Jesper Dangaard Brouer To: bpf@vger.kernel.org Cc: Jesper Dangaard Brouer , netdev@vger.kernel.org, Daniel Borkmann , Alexei Starovoitov , maze@google.com, lmb@cloudflare.com, shaun@tigera.io, Lorenzo Bianconi , marek@cloudflare.com, John Fastabend , Jakub Kicinski , eyal.birger@gmail.com, colrack@gmail.com Date: Thu, 17 Dec 2020 18:26:45 +0100 Message-ID: <160822600586.3481451.10079433672868181632.stgit@firesoul> In-Reply-To: <160822594178.3481451.1208057539613401103.stgit@firesoul> References: <160822594178.3481451.1208057539613401103.stgit@firesoul> User-Agent: StGit/0.19 MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org X-Patchwork-Delegate: bpf@iogearbox.net This demonstrate how bpf_check_mtu() helper can easily be used together with bpf_skb_adjust_room() helper, prior to doing size adjustment, as delta argument is already setup. Hint: This specific test can be selected like this: ./test_progs -t cls_redirect Signed-off-by: Jesper Dangaard Brouer --- .../selftests/bpf/progs/test_cls_redirect.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/tools/testing/selftests/bpf/progs/test_cls_redirect.c b/tools/testing/selftests/bpf/progs/test_cls_redirect.c index c9f8464996ea..3c1e042962e6 100644 --- a/tools/testing/selftests/bpf/progs/test_cls_redirect.c +++ b/tools/testing/selftests/bpf/progs/test_cls_redirect.c @@ -70,6 +70,7 @@ typedef struct { uint64_t errors_total_encap_adjust_failed; uint64_t errors_total_encap_buffer_too_small; uint64_t errors_total_redirect_loop; + uint64_t errors_total_encap_mtu_violate; } metrics_t; typedef enum { @@ -407,6 +408,7 @@ static INLINING ret_t forward_with_gre(struct __sk_buff *skb, encap_headers_t *e payload_off - sizeof(struct ethhdr) - sizeof(struct iphdr); int32_t delta = sizeof(struct gre_base_hdr) - encap_overhead; uint16_t proto = ETH_P_IP; + uint32_t mtu_len = 0; /* Loop protection: the inner packet's TTL is decremented as a safeguard * against any forwarding loop. As the only interesting field is the TTL @@ -479,6 +481,11 @@ static INLINING ret_t forward_with_gre(struct __sk_buff *skb, encap_headers_t *e } } + if (bpf_check_mtu(skb, skb->ifindex, &mtu_len, delta, 0)) { + metrics->errors_total_encap_mtu_violate++; + return TC_ACT_SHOT; + } + if (bpf_skb_adjust_room(skb, delta, BPF_ADJ_ROOM_NET, BPF_F_ADJ_ROOM_FIXED_GSO | BPF_F_ADJ_ROOM_NO_CSUM_RESET) || From patchwork Thu Dec 17 17:26:50 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jesper Dangaard Brouer X-Patchwork-Id: 11980331 X-Patchwork-Delegate: bpf@iogearbox.net 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=-15.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=unavailable 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 81A33C3526A for ; Thu, 17 Dec 2020 17:28:48 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 6837A2395A for ; Thu, 17 Dec 2020 17:28:48 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729160AbgLQR2d (ORCPT ); Thu, 17 Dec 2020 12:28:33 -0500 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:58883 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729996AbgLQR2b (ORCPT ); Thu, 17 Dec 2020 12:28:31 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1608226023; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=syTvU0jrp0ayBwL6zMDhSOwpXyqcnTrTsriNHwa1rMo=; b=E9JjvYLoLj1akDnbsd2pwN+jCmtvOQUn/7/9jUZG6tDatn3QMlLJf8cU6h2jjWu/+d9zmV gVIZfYfQye2tL6wGJ4D1zQAyIkoXnDshPsDY/7KmDt6vfaExU7Y3Ro2RxXIrGDvfFgLDL0 rO6dcf5fT7P/lMpRQhaG6HInPElwnac= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-175-AS0V1oIUNmqur6DBrWl4Jg-1; Thu, 17 Dec 2020 12:26:58 -0500 X-MC-Unique: AS0V1oIUNmqur6DBrWl4Jg-1 Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.phx2.redhat.com [10.5.11.13]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id D733318C8C3B; Thu, 17 Dec 2020 17:26:55 +0000 (UTC) Received: from firesoul.localdomain (unknown [10.40.208.19]) by smtp.corp.redhat.com (Postfix) with ESMTP id DDE2F60D01; Thu, 17 Dec 2020 17:26:51 +0000 (UTC) Received: from [192.168.42.3] (localhost [IPv6:::1]) by firesoul.localdomain (Postfix) with ESMTP id F1B2D32138454; Thu, 17 Dec 2020 18:26:50 +0100 (CET) Subject: [PATCH bpf-next V9 7/7] bpf/selftests: tests using bpf_check_mtu BPF-helper From: Jesper Dangaard Brouer To: bpf@vger.kernel.org Cc: Jesper Dangaard Brouer , netdev@vger.kernel.org, Daniel Borkmann , Alexei Starovoitov , maze@google.com, lmb@cloudflare.com, shaun@tigera.io, Lorenzo Bianconi , marek@cloudflare.com, John Fastabend , Jakub Kicinski , eyal.birger@gmail.com, colrack@gmail.com Date: Thu, 17 Dec 2020 18:26:50 +0100 Message-ID: <160822601093.3481451.9135115478358953965.stgit@firesoul> In-Reply-To: <160822594178.3481451.1208057539613401103.stgit@firesoul> References: <160822594178.3481451.1208057539613401103.stgit@firesoul> User-Agent: StGit/0.19 MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.13 Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org X-Patchwork-Delegate: bpf@iogearbox.net Adding selftest for BPF-helper bpf_check_mtu(). Making sure it can be used from both XDP and TC. Signed-off-by: Jesper Dangaard Brouer --- tools/testing/selftests/bpf/prog_tests/check_mtu.c | 204 ++++++++++++++++++++ tools/testing/selftests/bpf/progs/test_check_mtu.c | 196 +++++++++++++++++++ 2 files changed, 400 insertions(+) create mode 100644 tools/testing/selftests/bpf/prog_tests/check_mtu.c create mode 100644 tools/testing/selftests/bpf/progs/test_check_mtu.c diff --git a/tools/testing/selftests/bpf/prog_tests/check_mtu.c b/tools/testing/selftests/bpf/prog_tests/check_mtu.c new file mode 100644 index 000000000000..b5d0c3a9abe8 --- /dev/null +++ b/tools/testing/selftests/bpf/prog_tests/check_mtu.c @@ -0,0 +1,204 @@ +// SPDX-License-Identifier: GPL-2.0 +/* Copyright (c) 2020 Jesper Dangaard Brouer */ + +#include /* before test_progs.h, avoid bpf_util.h redefines */ + +#include +#include "test_check_mtu.skel.h" +#include + +#include +#include + +#define IFINDEX_LO 1 + +static __u32 duration; /* Hint: needed for CHECK macro */ + +static int read_mtu_device_lo(void) +{ + const char *filename = "/sys/devices/virtual/net/lo/mtu"; + char buf[11] = {}; + int value; + int fd; + + fd = open(filename, 0, O_RDONLY); + if (fd == -1) + return -1; + + if (read(fd, buf, sizeof(buf)) == -1) + return -2; + close(fd); + + value = strtoimax(buf, NULL, 10); + if (errno == ERANGE) + return -3; + + return value; +} + +static void test_check_mtu_xdp_attach(struct bpf_program *prog) +{ + int err = 0; + int fd; + + fd = bpf_program__fd(prog); + err = bpf_set_link_xdp_fd(IFINDEX_LO, fd, XDP_FLAGS_SKB_MODE); + if (CHECK(err, "XDP-attach", "failed")) + return; + + bpf_set_link_xdp_fd(IFINDEX_LO, -1, 0); +} + +static void test_check_mtu_run_xdp(struct test_check_mtu *skel, + struct bpf_program *prog, + __u32 mtu_expect) +{ + const char *prog_name = bpf_program__name(prog); + int retval_expect = XDP_PASS; + __u32 mtu_result = 0; + char buf[256]; + int err; + + struct bpf_prog_test_run_attr tattr = { + .repeat = 1, + .data_in = &pkt_v4, + .data_size_in = sizeof(pkt_v4), + .data_out = buf, + .data_size_out = sizeof(buf), + .prog_fd = bpf_program__fd(prog), + }; + + memset(buf, 0, sizeof(buf)); + + err = bpf_prog_test_run_xattr(&tattr); + CHECK_ATTR(err != 0 || errno != 0, "bpf_prog_test_run", + "prog_name:%s (err %d errno %d retval %d)\n", + prog_name, err, errno, tattr.retval); + + CHECK(tattr.retval != retval_expect, "retval", + "progname:%s unexpected retval=%d expected=%d\n", + prog_name, tattr.retval, retval_expect); + + /* Extract MTU that BPF-prog got */ + mtu_result = skel->bss->global_bpf_mtu_xdp; + CHECK(mtu_result != mtu_expect, "MTU-compare-user", + "failed (MTU user:%d bpf:%d)", mtu_expect, mtu_result); +} + +static void test_check_mtu_xdp(__u32 mtu, __u32 ifindex) +{ + struct test_check_mtu *skel; + int err; + + skel = test_check_mtu__open(); + if (CHECK(!skel, "skel_open", "failed")) + return; + + /* Update "constants" in BPF-prog *BEFORE* libbpf load */ + skel->rodata->GLOBAL_USER_MTU = mtu; + skel->rodata->GLOBAL_USER_IFINDEX = ifindex; + + err = test_check_mtu__load(skel); + if (CHECK(err, "skel_load", "failed: %d\n", err)) + goto cleanup; + + test_check_mtu_run_xdp(skel, skel->progs.xdp_use_helper, mtu); + test_check_mtu_run_xdp(skel, skel->progs.xdp_exceed_mtu, mtu); + test_check_mtu_run_xdp(skel, skel->progs.xdp_minus_delta, mtu); + +cleanup: + test_check_mtu__destroy(skel); +} + +static void test_check_mtu_run_tc(struct test_check_mtu *skel, + struct bpf_program *prog, + __u32 mtu_expect) +{ + const char *prog_name = bpf_program__name(prog); + int retval_expect = BPF_OK; + __u32 mtu_result = 0; + char buf[256]; + int err; + + struct bpf_prog_test_run_attr tattr = { + .repeat = 1, + .data_in = &pkt_v4, + .data_size_in = sizeof(pkt_v4), + .data_out = buf, + .data_size_out = sizeof(buf), + .prog_fd = bpf_program__fd(prog), + }; + + memset(buf, 0, sizeof(buf)); + + err = bpf_prog_test_run_xattr(&tattr); + CHECK_ATTR(err != 0 || errno != 0, "bpf_prog_test_run", + "prog_name:%s (err %d errno %d retval %d)\n", + prog_name, err, errno, tattr.retval); + + CHECK(tattr.retval != retval_expect, "retval", + "progname:%s unexpected retval=%d expected=%d\n", + prog_name, tattr.retval, retval_expect); + + /* Extract MTU that BPF-prog got */ + mtu_result = skel->bss->global_bpf_mtu_tc; + CHECK(mtu_result != mtu_expect, "MTU-compare-user", + "failed (MTU user:%d bpf:%d)", mtu_expect, mtu_result); +} + + +static void test_check_mtu_tc(__u32 mtu, __u32 ifindex) +{ + struct test_check_mtu *skel; + int err; + + skel = test_check_mtu__open(); + if (CHECK(!skel, "skel_open", "failed")) + return; + + /* Update "constants" in BPF-prog *BEFORE* libbpf load */ + skel->rodata->GLOBAL_USER_MTU = mtu; + skel->rodata->GLOBAL_USER_IFINDEX = ifindex; + + err = test_check_mtu__load(skel); + if (CHECK(err, "skel_load", "failed: %d\n", err)) + goto cleanup; + + test_check_mtu_run_tc(skel, skel->progs.tc_use_helper, mtu); + test_check_mtu_run_tc(skel, skel->progs.tc_exceed_mtu, mtu); + test_check_mtu_run_tc(skel, skel->progs.tc_exceed_mtu_da, mtu); + test_check_mtu_run_tc(skel, skel->progs.tc_minus_delta, mtu); +cleanup: + test_check_mtu__destroy(skel); +} + +void test_check_mtu(void) +{ + struct test_check_mtu *skel; + __u32 mtu_lo; + + skel = test_check_mtu__open_and_load(); + if (CHECK(!skel, "open and load skel", "failed")) + return; /* Exit if e.g. helper unknown to kernel */ + + if (test__start_subtest("bpf_check_mtu XDP-attach")) + test_check_mtu_xdp_attach(skel->progs.xdp_use_helper_basic); + + test_check_mtu__destroy(skel); + + mtu_lo = read_mtu_device_lo(); + if (CHECK(mtu_lo < 0, "reading MTU value", "failed (err:%d)", mtu_lo)) + return; + + if (test__start_subtest("bpf_check_mtu XDP-run")) + test_check_mtu_xdp(mtu_lo, 0); + + if (test__start_subtest("bpf_check_mtu XDP-run ifindex-lookup")) + test_check_mtu_xdp(mtu_lo, IFINDEX_LO); + + if (test__start_subtest("bpf_check_mtu TC-run")) + test_check_mtu_tc(mtu_lo, 0); + + if (test__start_subtest("bpf_check_mtu TC-run ifindex-lookup")) + test_check_mtu_tc(mtu_lo, IFINDEX_LO); +} diff --git a/tools/testing/selftests/bpf/progs/test_check_mtu.c b/tools/testing/selftests/bpf/progs/test_check_mtu.c new file mode 100644 index 000000000000..91a026b8d458 --- /dev/null +++ b/tools/testing/selftests/bpf/progs/test_check_mtu.c @@ -0,0 +1,196 @@ +// SPDX-License-Identifier: GPL-2.0 +/* Copyright (c) 2020 Jesper Dangaard Brouer */ + +#include +#include +#include + +#include +#include + +char _license[] SEC("license") = "GPL"; + +/* Userspace will update with MTU it can see on device */ +static volatile const int GLOBAL_USER_MTU; +static volatile const __u32 GLOBAL_USER_IFINDEX; + +/* BPF-prog will update these with MTU values it can see */ +__u32 global_bpf_mtu_xdp = 0; +__u32 global_bpf_mtu_tc = 0; + +SEC("xdp") +int xdp_use_helper_basic(struct xdp_md *ctx) +{ + __u32 mtu_len = 0; + + if (bpf_check_mtu(ctx, 0, &mtu_len, 0, 0)) + return XDP_ABORTED; + + return XDP_PASS; +} + +SEC("xdp") +int xdp_use_helper(struct xdp_md *ctx) +{ + int retval = XDP_PASS; /* Expected retval on successful test */ + __u32 mtu_len = 0; + __u32 ifindex = 0; + int delta = 0; + + /* When ifindex is zero, save net_device lookup and use ctx netdev */ + if (GLOBAL_USER_IFINDEX > 0) + ifindex = GLOBAL_USER_IFINDEX; + + if (bpf_check_mtu(ctx, ifindex, &mtu_len, delta, 0)) { + /* mtu_len is also valid when check fail */ + retval = XDP_ABORTED; + goto out; + } + + if (GLOBAL_USER_MTU != mtu_len) + retval = XDP_DROP; + +out: + global_bpf_mtu_xdp = mtu_len; + return retval; +} + +SEC("xdp") +int xdp_exceed_mtu(struct xdp_md *ctx) +{ + void *data_end = (void *)(long)ctx->data_end; + void *data = (void *)(long)ctx->data; + __u32 ifindex = GLOBAL_USER_IFINDEX; + __u32 data_len = data_end - data; + int retval = XDP_ABORTED; /* Fail */ + __u32 mtu_len = 0; + + int delta; + int err; + + /* Exceed MTU with 1 via delta adjust */ + delta = GLOBAL_USER_MTU - (data_len - ETH_HLEN) + 1; + + if ((err = bpf_check_mtu(ctx, ifindex, &mtu_len, delta, 0))) { + retval = XDP_PASS; /* Success in exceeding MTU check */ + if (err != BPF_MTU_CHK_RET_FRAG_NEEDED) + retval = XDP_DROP; + } + + global_bpf_mtu_xdp = mtu_len; + return retval; +} + +SEC("xdp") +int xdp_minus_delta(struct xdp_md *ctx) +{ + int retval = XDP_PASS; /* Expected retval on successful test */ + void *data_end = (void *)(long)ctx->data_end; + void *data = (void *)(long)ctx->data; + __u32 ifindex = GLOBAL_USER_IFINDEX; + __u32 data_len = data_end - data; + __u32 mtu_len = 0; + int delta; + + /* Boarderline test case: Minus delta exceeding packet length allowed */ + delta = -((data_len - ETH_HLEN) + 1); + + /* Minus length (adjusted via delta) still pass MTU check, other helpers + * are responsible for catching this, when doing actual size adjust + */ + if (bpf_check_mtu(ctx, ifindex, &mtu_len, delta, 0)) + retval = XDP_ABORTED; + + global_bpf_mtu_xdp = mtu_len; + return retval; +} + +SEC("classifier") +int tc_use_helper(struct __sk_buff *ctx) +{ + int retval = BPF_OK; /* Expected retval on successful test */ + __u32 mtu_len = 0; + int delta = 0; + + if (bpf_check_mtu(ctx, 0, &mtu_len, delta, 0)) { + retval = BPF_DROP; + goto out; + } + + if (GLOBAL_USER_MTU != mtu_len) + retval = BPF_REDIRECT; +out: + global_bpf_mtu_tc = mtu_len; + return retval; +} + +SEC("classifier") +int tc_exceed_mtu(struct __sk_buff *ctx) +{ + __u32 ifindex = GLOBAL_USER_IFINDEX; + int retval = BPF_DROP; /* Fail */ + __u32 skb_len = ctx->len; + __u32 mtu_len = 0; + int delta; + int err; + + /* Exceed MTU with 1 via delta adjust */ + delta = GLOBAL_USER_MTU - (skb_len - ETH_HLEN) + 1; + + if ((err = bpf_check_mtu(ctx, ifindex, &mtu_len, delta, 0))) { + retval = BPF_OK; /* Success in exceeding MTU check */ + if (err != BPF_MTU_CHK_RET_FRAG_NEEDED) + retval = BPF_DROP; + } + + global_bpf_mtu_tc = mtu_len; + return retval; +} + +SEC("classifier") +int tc_exceed_mtu_da(struct __sk_buff *ctx) +{ + /* SKB Direct-Access variant */ + void *data_end = (void *)(long)ctx->data_end; + void *data = (void *)(long)ctx->data; + __u32 ifindex = GLOBAL_USER_IFINDEX; + __u32 data_len = data_end - data; + int retval = BPF_DROP; /* Fail */ + __u32 mtu_len = 0; + int delta; + int err; + + /* Exceed MTU with 1 via delta adjust */ + delta = GLOBAL_USER_MTU - (data_len - ETH_HLEN) + 1; + + if ((err = bpf_check_mtu(ctx, ifindex, &mtu_len, delta, 0))) { + retval = BPF_OK; /* Success in exceeding MTU check */ + if (err != BPF_MTU_CHK_RET_FRAG_NEEDED) + retval = BPF_DROP; + } + + global_bpf_mtu_tc = mtu_len; + return retval; +} + +SEC("classifier") +int tc_minus_delta(struct __sk_buff *ctx) +{ + int retval = BPF_OK; /* Expected retval on successful test */ + __u32 ifindex = GLOBAL_USER_IFINDEX; + __u32 skb_len = ctx->len; + __u32 mtu_len = 0; + int delta; + + /* Boarderline test case: Minus delta exceeding packet length allowed */ + delta = -((skb_len - ETH_HLEN) + 1); + + /* Minus length (adjusted via delta) still pass MTU check, other helpers + * are responsible for catching this, when doing actual size adjust + */ + if (bpf_check_mtu(ctx, ifindex, &mtu_len, delta, 0)) + retval = BPF_DROP; + + global_bpf_mtu_xdp = mtu_len; + return retval; +}